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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

    grains in polycrystalline samples during tensile deformation. We have shown that the resulting 3D reciprocal space maps from tensile deformed copper comprise a pronounced structure, consisting of bright sharp peaks superimposed on a cloud of enhanced intensity. Based on the integrated intensity...

  2. 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 ...

  3. Mechanical Properties and Deformation Behavior of Bulk Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Alexander Yu. Churyumov

    2012-12-01

    Full Text Available Metallic glasses demonstrate unique properties, including large elastic limit and high strength, which make them attractive for practical applications. Unlike crystalline alloys, metallic glasses, in general, do not exhibit a strain hardening effect, while plastic deformation at room temperature is localized in narrow shear bands. Room-temperature mechanical properties and deformation behavior of bulk metallic glassy samples and the crystal-glassy composites are reviewed in the present paper.

  4. Mechanical Properties and Deformation Behavior of Bulk Metallic Glasses

    OpenAIRE

    Alexander Yu. Churyumov; Louzguine-Luzgin, Dmitri V.; Larissa V. Louzguina-Luzgina

    2012-01-01

    Metallic glasses demonstrate unique properties, including large elastic limit and high strength, which make them attractive for practical applications. Unlike crystalline alloys, metallic glasses, in general, do not exhibit a strain hardening effect, while plastic deformation at room temperature is localized in narrow shear bands. Room-temperature mechanical properties and deformation behavior of bulk metallic glassy samples and the crystal-glassy composites are reviewed in the present paper.

  5. Microstructure and Room Temperature Compressive Deformation Behavior of Cold-Sprayed High-Strength Cu Bulk Material

    Science.gov (United States)

    Kim, Young-Kyun; Kim, Kyu-Sik; Kim, Hyung-Jun; Park, Chan-Hee; Lee, Kee-Ahn

    2017-10-01

    This study investigated the room temperature compressive deformation behavior of Cu bulk material manufactured by cold spray process. Initial microstructural observation identified a unique microstructure with grain size of hundreds of nm in the particle interface area and relatively coarse grains in all other areas. Room temperature compressive results confirmed cold-sprayed Cu to have a yield strength of 340 MPa, which is similar to materials manufactured by severe plastic deformation process such as equal channel angular press. In addition, strain softening phenomenon, which is rarely found in room temperature compressive deformation, was observed. According to such unique characteristics, continuous microstructure evolution and surface fractures according to the strain ( ɛ t = 0.3/0.6/0.9) of the material were observed, and considerations were made for deformation and fracture behavior. Microstructural observation after compressive deformation confirmed that average grain size decreased as the strain increased, and the fraction of the low-angle boundary, which has an indirect relationship with dislocation density, showed a tendency to decrease in ɛ t = 0.3-0.6 region where the strain softening phenomenon occurs. Based on the results described above, this study was able to identify the possibility of manufacturing cold-sprayed Cu bulk material for structural material and its room temperature deformation behavior.

  6. Formation and subdivision of deformation structures during plastic deformation

    DEFF Research Database (Denmark)

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

    2006-01-01

    During plastic deformation of metals and alloys, dislocations arrange in ordered patterns. How and when these self-organization processes take place have remained elusive, because in situ observations have not been feasible. We present an x-ray diffraction method that provided data on the dynamics...... 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 behavior....... Insight into these processes is relevant for an understanding of the strength and work-hardening of deformed materials....

  7. 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...

  8. Numerical estimation of deformation energy of selected bulk oilseeds in compression loading

    Science.gov (United States)

    Demirel, C.; Kabutey, A.; Herak, D.; Gurdil, G. A. K.

    2017-09-01

    This paper aimed at the determination of the deformation energy of some bulk oilseeds or kernels namely oil palm, sunflower, rape and flax in linear pressing applying the trapezoidal rule which is characterized by the area under the force and deformation curve.The bulk samples were measured at the initial pressing height of 60 mm with the vessel diameter of 60 mm where they were compressed under the universal compression machine at a maximum force of 200 kN and speed of 5 mm/min.Based on the compression test, the optimal deformation energy for recovering the oil was observed at a force of 163 kN where there was no seed/kernel cake ejection in comparison to the initial maximum force used particularly for rape and flax bulk oilseeds.This information is needed for analyzing the energy efficiency of the non-linear compression process involving a mechanical screw press or expeller.

  9. Structural determinants in the bulk heterojunction.

    Science.gov (United States)

    Acocella, Angela; Höfinger, Siegfried; Haunschmid, Ernst; Pop, Sergiu C; Narumi, Tetsu; Yasuoka, Kenji; Yasui, Masato; Zerbetto, Francesco

    2018-02-21

    Photovoltaics is one of the key areas in renewable energy research with remarkable progress made every year. Here we consider the case of a photoactive material and study its structural composition and the resulting consequences for the fundamental processes driving solar energy conversion. A multiscale approach is used to characterize essential molecular properties of the light-absorbing layer. A selection of bulk-representative pairs of donor/acceptor molecules is extracted from the molecular dynamics simulation of the bulk heterojunction and analyzed at increasing levels of detail. Significantly increased ground state energies together with an array of additional structural characteristics are identified that all point towards an auxiliary role of the material's structural organization in mediating charge-transfer and -separation. Mechanistic studies of the type presented here can provide important insights into fundamental principles governing solar energy conversion in next-generation photovoltaic devices.

  10. Deformation Characteristics of Composite Structures

    Directory of Open Access Journals (Sweden)

    Theddeus T. AKANO

    2016-08-01

    Full Text Available The composites provide design flexibility because many of them can be moulded into complex shapes. The carbon fibre-reinforced epoxy composites exhibit excellent fatigue tolerance and high specific strength and stiffness which have led to numerous advanced applications ranging from the military and civil aircraft structures to the consumer products. However, the modelling of the beams undergoing the arbitrarily large displacements and rotations, but small strains, is a common problem in the application of these engineering composite systems. This paper presents a nonlinear finite element model which is able to estimate the deformations of the fibre-reinforced epoxy composite beams. The governing equations are based on the Euler-Bernoulli beam theory (EBBT with a von Kármán type of kinematic nonlinearity. The anisotropic elasticity is employed for the material model of the composite material. Moreover, the characterization of the mechanical properties of the composite material is achieved through a tensile test, while a simple laboratory experiment is used to validate the model. The results reveal that the composite fibre orientation, the type of applied load and boundary condition, affect the deformation characteristics of the composite structures. The nonlinearity is an important factor that should be taken into consideration in the analysis of the fibre-reinforced epoxy composites.

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

    DEFF Research Database (Denmark)

    West, Stine; Schmidt, Søren; Sørensen, Henning Osholm

    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...

  12. 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...... sections: structural evolution by grain subdivision, recovery and recrystallisation and strength-structure relationships....

  13. Structural refinement and coarsening in deformed metals

    DEFF Research Database (Denmark)

    Hansen, N.; Huang, X.; Xing, Q.

    2005-01-01

    The microstructural refinement by plastic deformation is analysed in terms of key parameters, the spacing between and the misorientation angle across the boundaries subdividing the structure. Coarsening of such structures by annealing is also characterised. For both deformed and annealed structur...

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

    DEFF Research Database (Denmark)

    Pantleon, Wolfgang; Wejdemann, Christian; Jakobsen, Bo

    2014-01-01

    With high-angular resolution three-dimensional X-ray diffraction (3DXRD), quantitative information is gained about dislocation structures in individual grains in the bulk of a macroscopic specimen by acquiring reciprocal space maps. In high-resolution 3D reciprocal space maps of tensile...... 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...

  15. Creep deformation of restorative resin-composites intended for bulk-fill placement.

    Science.gov (United States)

    El-Safty, S; Silikas, N; Watts, D C

    2012-08-01

    To determine the creep deformation of several "bulk-fill" resin-composite formulations in comparison with some other types. Six resin-composites; four bulk-fill and two conventional were investigated. Stainless steel split molds (4 mm × 6 mm) were used to prepare cylindrical specimens for creep testing. Specimens were thoroughly irradiated with 650 mW cm(-2). A total of 10 specimens for each material were divided into two groups (n = 5) according to the storage condition; Group A stored dry at 37 °C for 24h and Group B stored in distilled water at 37 °C in an incubator for 24h. Each specimen was loaded (20 MPa) for 2h and unloaded for 2h. The strain deformation was recorded continuously for 4h. Statistical analysis was performed using a two-way ANOVA followed by one-way ANOVA and the Bonferroni post hoc test at a significance level of a = 0.05. The maximum creep strain % ranged from 0.72% up to 1.55% for Group A and the range for Group B increased from 0.79% up to 1.80% due to water sorption. Also, the permanent set ranged from 0.14% up to 0.47% for Group A and from 0.20% up to 0.59% for Group B. Dependent on the material and storage condition, the percentage of creep strain recovery ranged between 64% and 81%. Increased filler loading in the bulk-fill materials decreased the creep strain magnitude. Creep deformation of all studied resin-composites increased with wet storage. The "bulk-fill" composites exhibited an acceptable creep deformation and within the range exhibited by other resin-composites. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  16. Deformation-Induced Martensitic Transformation in Cu-Zr-Zn Bulk Metallic Glass Composites

    Directory of Open Access Journals (Sweden)

    Dianyu Wu

    2015-11-01

    Full Text Available The microstructures and mechanical properties of (Cu0.5Zr0.5100−xZnx (x = 0, 1.5, 2.5, 4.5, 7, 10, and 14 at. % bulk metallic glass (BMG composites were studied. CuZr martensitic crystals together with minor B2 CuZr and amorphous phases dominate the microstructures of the as-quenched samples with low Zn additions (x = 0, 1.5, and 2.5 at. %, while B2 CuZr and amorphous phases being accompanied with minor martensitic crystals form at a higher Zn content (x = 4.5, 7, 10, and 14 at. %. The fabricated Cu-Zr-Zn BMG composites exhibit macroscopically appreciable compressive plastic strain and obvious work-hardening due to the formation of multiple shear bands and the deformation-induced martensitic transformation (MT within B2 crystals. The present BMG composites could be a good candidate as high-performance structural materials.

  17. 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.

  18. Deformation behaviors of a Ti-based bulk metallic glass composite in the dendrite softening region

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Jing; Li, Jinshan; Wang, Jun, E-mail: nwpuwj@nwpu.edu.cn; Kou, Hongchao

    2016-01-20

    Deformation behaviors of the Ti{sub 50}Zr{sub 20}Nb{sub 12}Cu{sub 5}Be{sub 13} bulk metallic glass composite in the dendrite softening region have been investigated using uniaxial compressive and tensile tests. All the compressive stress–strain curves show work-hardening phenomenon with the same tendency, the tensile stress–strain curves show work-softening phenomenon. The strain rate sensitivity exponent ranges from 0.061 to 0.072 in the compressive tests, and 0.33 to 0.38 in the tensile tests. The activation volume of the Ti{sub 50}Zr{sub 20}Nb{sub 12}Cu{sub 5}Be{sub 13} bulk metallic glass composite at 710 K ranges from 1.6 nm{sup 3} to 2.5 nm{sup 3} under compressive tests and 1.0 nm{sup 3} to 2.7 nm{sup 3} under tensile tests, indicating that there is a migration of atomic group (about 170–180 atoms) during the deformation. The dendrite of the Ti{sub 50}Zr{sub 20}Nb{sub 12}Cu{sub 5}Be{sub 13} BMGC has been well spheroidized and undergoes severe plasticity deformation after the deformation in the dendrite softening region.

  19. Deformed configurations, band structures and spectroscopic ...

    Indian Academy of Sciences (India)

    2014-03-20

    Mar 20, 2014 ... Home; Journals; Pramana – Journal of Physics; Volume 82; Issue 4. Deformed ... Deformed structure; constrained Hartree–Fock; shell closure; rotational band; electromagnetic properties. ... Department of Physics, IIT Ropar, Rupnagar 140 001, India; Institute of Physics, Bhubaneswar 751 005, India ...

  20. 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

  1. 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...

  2. Effect of bulk modulus on deformation of the brain under rotational accelerations

    Science.gov (United States)

    Ganpule, S.; Daphalapurkar, N. P.; Cetingul, M. P.; Ramesh, K. T.

    2017-12-01

    Traumatic brain injury such as that developed as a consequence of blast is a complex injury with a broad range of symptoms and disabilities. Computational models of brain biomechanics hold promise for illuminating the mechanics of traumatic brain injury and for developing preventive devices. However, reliable material parameters are needed for models to be predictive. Unfortunately, the properties of human brain tissue are difficult to measure, and the bulk modulus of brain tissue in particular is not well characterized. Thus, a wide range of bulk modulus values are used in computational models of brain biomechanics, spanning up to three orders of magnitude in the differences between values. However, the sensitivity of these variations on computational predictions is not known. In this work, we study the sensitivity of a 3D computational human head model to various bulk modulus values. A subject-specific human head model was constructed from T1-weighted MRI images at 2-mm3 voxel resolution. Diffusion tensor imaging provided data on spatial distribution and orientation of axonal fiber bundles for modeling white matter anisotropy. Non-injurious, full-field brain deformations in a human volunteer were used to assess the simulated predictions. The comparison suggests that a bulk modulus value on the order of GPa gives the best agreement with experimentally measured in vivo deformations in the human brain. Further, simulations of injurious loading suggest that bulk modulus values on the order of GPa provide the closest match with the clinical findings in terms of predicated injured regions and extent of injury.

  3. Ground deformations in collapsed caldera structures

    Science.gov (United States)

    De Natale, Giuseppe; Pingue, Folco

    1993-09-01

    A method is presented to analyze the effect of stress-strain discontinuities on the ground deformations generated by a pressure source. This is meant to simulate the effects due to caldera structures, likely to present fractured zones at the borders of the collapsed area. A method originally developed by Crouch (1976) to solve plane-strain problems has been used to simulate deformation curves for several source and discontinuity geometries. The main result is that the location of the discontinuities controls the extension of the deformed zone, and always reduces it with respect to a continuous medium. With respect to a homogeneous medium the presence of lateral discontinuities also acts towards lowering the overpressure required to produce a given amount of deformation. These results indicate that, when analyzing ground deformations in calderas, the use of classical methods involving continuous media should be avoided, or at least taken with caution. These methods, in fact, assume that the extension of the deformed zone is only linked to the source depth. Some examples of ground deformations in active calderas have been analyzed in the framework of the results obtained from theoretical modeling. Four calderas recently affected by ground deformations have been considered: Rabaul (New Guinea), Campi Flegrei (Italy), Long Valley and Yellowstone (U.S.A.). The effects of collapsed structures on the deformation field are possibly evidenced for all the four calderas. At Rabaul and Campi Flegrei, the fracture systems mainly affecting the ground deformations probably represent younger, innermost collapses and are well evidenced by seismicity studies. Ground deformations are here concentrated in an area much smaller than the one enclosed by geologically visible caldera rims. In particular, at Rabaul, the effect of the innermost collapse can explain the high concentration of the uplift in the period 1971-1985, previously modeled by a very shallow source (1-3 km) in terms of

  4. Periodic Orbits and Deformed Shell Structure

    OpenAIRE

    Arita, K.; Magner, A. G.; Matsuyanagi, K.

    2002-01-01

    Relationship between quantum shell structure and classical periodic orbits is briefly reviewed on the basis of semi-classical trace formula. Using the spheroidal cavity model, it is shown that three-dimensional periodic orbits, which are born out of bifurcation of planar orbits at large prolate deformations, generate the superdeformed shell structure.

  5. Mechanisms of compressive deformation and failure of porous bulk metallic glasses

    Science.gov (United States)

    Gouripriya, S.; Tandaiya, Parag

    2017-06-01

    Bulk metallic glasses (BMGs) are a new class of engineering materials having strengths as high as 10 times that of conventional steels, but show no significant plastic strain at fracture. By introducing pores, their strain to failure has been shown to improve under uniaxial compression. In this work, three-dimensional finite element simulations of uniaxial compression are carried out on Pd-based porous BMGs having a wide range of pore volume fraction (1.9%-60%) with emphasis on understanding the underlying deformation and failure mechanisms. The resulting stress-strain curves agree reasonably well with existing experimental results. The simulations clearly bring out different failure mechanisms in low porosity BMGs and high porosity BMG foams. For low porosity BMGs (below 20%), the deformation and failure involves nucleation of shear bands around the pore diameter, linking of the shear bands with adjacent pores finally leading to initiation of ductile cracking within the shear bands. For high porosity BMG foams, the mechanism of deformation involves reduction in porosity of the material, self-contact of the pores, and their collapse on themselves causing densification of the material leading to apparent hardening in the stress strain behavior. The effect of pore geometry is also studied by considering ellipsoidal pores of volume fraction 3% and 11%. For ellipsoidal pores, the failure mechanisms are found to differ significantly when the orientation of the major axis of the pore vis-a-vis the loading axis is changed.

  6. 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. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Evolution of fractal structures in dislocation ensembles during plastic deformation.

    Science.gov (United States)

    Vinogradov, A; Yasnikov, I S; Estrin, Y

    2012-05-18

    Based on the irreversible thermodynamics approach to dislocation plasticity of metals, a simple description of the dislocation density evolution and strain hardening was suggested. An analytical expression for the fractal dimension (FD) of a cellular (or tangled) dislocation structure evolving in the course of plastic deformation was obtained on the basis of the dislocation model proposed. This makes it possible to trace the variation of FD of the dislocation cell structure with strain by just measuring the macroscopic stress-strain curve. The FD behavior predicted in this way showed good agreement with the experimentally measured FD evolution at different stages of deformation of a Ni single crystal and a Cu polycrystal. One new result following from the present model is that the FD of the bulk dislocation structure in a deforming metal peaks at a certain strain close to the onset of necking. The significance of fractal analysis as an informative index to follow the spatial evolution of dislocation structures approaching the critical state is highlighted.

  8. Thermoplastic deformation of ferromagnetic CoFe-based bulk metallic glasses

    Science.gov (United States)

    Wu, Chenguang; Hu, Renchao; Man, Qikui; Chang, Chuntao; Wang, Xinmin

    2017-12-01

    The superplastic deformation behavior of the ferromagnetic Co31Fe31Nb8B30 bulk metallic glass (BMG) in the supercooled liquid region was investigated. At a given temperature, the BMG exhibits a Newtonian behavior at low strain rates but a non-Newtonian behavior at high strain rates. The high thermal stability of this glassy alloy system offers an enough processing window to thermoplastic forming (TPF), and the strong processing ability was examined by simple micro-replication experiments. It is demonstrated that the TPF formability on length scales ranging down to nanometers can be achieved in the selected experimental condition. Based on the analysis of deformation behavior, the nearly full density sample (i.e. nearly 100%), was produced from water-atomized glassy powders and consolidated by the hot-pressing technique. The sample exhibits good soft-magnetic and mechanical properties, i.e., low coercive force of 0.43 Oe, high initial permeability of 4100 and high Vickers hardness 1398. These results suggest that the hot-pressing process opens up possibilities for the commercial exploitation of BMGs in engineering applications.

  9. Layered Structures in Deformed Metals and Alloys

    DEFF Research Database (Denmark)

    Hansen, Niels; Zhang, Xiaodan; Huang, Xiaoxu

    2014-01-01

    by the way of examples of different processing routes: friction, wire drawing, shot peening, high pressure torsion and rolling. The interlamellar spacing reaches from 5-10 nanometers to about one micrometer and the analysis will cover structural evolution, strengthening parameters and strength......-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....

  10. Investigation of crystallization kinetics and deformation behavior in supercooled liquid region of CuZr-based bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ke; Fan, Xinhui; Li, Bing; Li, Yanhong; Wang, Xin; Xu, Xuanxuan [Xi' an Technological Univ. (China). School of Material and Chemical Engineering

    2017-08-15

    In this paper, a systematic study of crystallization kinetics and deformation behavior is presented for (Cu{sub 50}Zr{sub 50}){sub 94}Al{sub 6} bulk metallic glass in the supercooled liquid region. Crystallization results showed that the activation energy for (Cu{sub 50}Zr{sub 50}){sub 94}Al{sub 6} was calculated using the Arrhenius equation in isothermal mode and the Kissinger-Akahira-Sunose method in non-isothermal mode. The activation energy was quite high compared with other bulk metallic glasses. Based on isothermal transformation kinetics described by the Johson-Mehl-Avrami model, the average Avrami exponent of about 3.05 implies a mainly diffusion controlled three-dimensional growth with an increasing nucleation rate during the crystallization. For warm deformation, the results showed that deformation behavior, composed of homogeneous and inhomogeneous deformation, is strongly dependent on strain rate and temperature. The homogeneous deformation transformed from non-Newtonian flow to Newtonian flow with a decrease in strain rate and an increase in temperature. It was found that the crystallization during high temperature deformation is induced by heating. The appropriate working temperature/strain rate combination for the alloy forming, without in-situ crystallization, was deduced by constructing an empirical deformation map. The optimum process condition for (Cu{sub 50}Zr{sub 50}){sub 94}Al{sub 6} can be expressed as T∝733 K and ∝ ε 10{sup -3} s{sup -1}.

  11. Fluid structure interaction problems in large deformation

    Science.gov (United States)

    Le Tallec, Patrick; Gerbeau, Jean-Frédéric; Hauret, Patrice; Vidrascu, Marina

    2005-12-01

    The present article deals with the simulation of fluid structure interaction problems in large deformation, and discusses two aspects of their numerical solution: (i) the derivation of energy conserving time integration schemes in presence of fluid structure coupling, moving grids, and nonlinear kinematic constraints such as incompressibility and contact, (ii) the introduction of adequate preconditioners efficiently chaining local fluid and structure solvers. Solutions are proposed, analyzed and tested using nonlinear energy correcting terms, and added mass based Dirichlet Neumann preconditioners. Numerical applications include nonlinear impact problems in elastodynamics and blood flows predictions within flexible arteries. To cite this article: P. Le Tallec et al., C. R. Mecanique 333 (2005).

  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.

    2006-01-01

    Bulk Cu60Zr20Ti20 metallic glass has been rolled at room temperature (RT) and cryogenic temperature (CIF) up to 97% in thickness reduction, and the dependences of microstructure on the strain and temperature have been investigated. It is revealed that as the deformation proceeds below a critical...

  13. 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

    A single grain growing in the bulk of a mildly deformed (30% thickness reduction through cold rolling) aluminium single crystal with an {001}<100> orientation (Cube orientation), is monitored during recrystallization with synchrotron radiation using topo-tomography. The formation and migration of...... of the analyzed facets is not closely related to any crystallographic {111} plane of neither the growing grain nor the disappearing deformed matrix. © 2013 The Japan Institute of Metals and Materials.......A single grain growing in the bulk of a mildly deformed (30% thickness reduction through cold rolling) aluminium single crystal with an {001} orientation (Cube orientation), is monitored during recrystallization with synchrotron radiation using topo-tomography. The formation and migration...

  14. Structural Characteristics and Physical Properties of Tectonically Deformed Coals

    Directory of Open Access Journals (Sweden)

    Yiwen Ju

    2012-01-01

    Full Text Available Different mechanisms of deformation could make different influence on inner structure and physical properties of tectonically deformed coal (TDC reservoirs. This paper discusses the relationship between macromolecular structure and physical properties of the Huaibei-Huainan coal mine areas in southern North China. The macromolecular structure and pore characteristics are systematically investigated by using techniques such as X-ray diffraction (XRD, high-resolution transmission electron microscopy (HRTEM, electron paramagnetic resonance (EPR, nuclear magnetic resonance (NMR, and low-temperature nitrogen adsorption method. The results suggest that under the directional stress, basic structural units (BSU arrangement is closer, and the orientation becomes stronger from brittle deformed coal to ductile deformed coal. Structural deformation directly influences the macromolecular structure of coal, which results in changes of pore structure. The nanoscale pores of the cataclastic coal structure caused by the brittle deformation are mainly mesopores, and the proportion of mesopores volume in ductile deformed coal diminishes rapidly. So the exploration and development potential of coalbed gas are good in reservoirs such as schistose structure coal, mortar structure coal and cataclastic structure coal. It also holds promise for a certain degree of brittle deformation and wrinkle structure coal of low ductile deformation or later superimposed by brittle deformation.

  15. Grain interaction mechanisms leading to intragranular orientation spread in tensile deformed bulk grains of interstitial-free steel

    DEFF Research Database (Denmark)

    Winther, Grethe; Wright, Jonathan P.; Schmidt, Søren

    2017-01-01

    The spatially resolved intragranular orientation spread in two representative bulk grains of interstitial-free steel deformed to 9% tension has been investigated. A three-dimensional X-ray diffraction microscopy experiment revealed that the two similarly oriented grains are both embedded in local...... environments representing the bulk texture, yet their deformation-induced rotations are very different. The ALAMEL model is employed to analyse the grain interaction mechanisms. Predictions of this model qualitatively agree with the directionality and magnitude of the experimental orientation spread. However......, quantitative agreement requires fine-tuning of the boundary conditions. The majority of the modelled slip is accounted for by four slip systems also predicted to be active by the classical Taylor model in uniaxial tension, and most of the orientation spread along the grain boundaries is caused by relative...

  16. Effect of stress states on the deformation behavior of Cu-based bulk metallic glass in the supercooled liquid region

    Energy Technology Data Exchange (ETDEWEB)

    Park, E.S., E-mail: espark@ameslab.gov [Division of Materials Science and Engineering, Ames Laboratory, U.S. DOE, Ames, IA 50011 (United States); Kim, H.J.; Bae, J.C. [Liquid Processing and Casting Technology R and D Department, Korea Institute of Industrial Technology, Inchon 406-130 (Korea, Republic of); Huh, M.Y. [Department of Materials Science and Engineering, Korea University, Seoul 136-701 (Korea, Republic of)

    2014-02-15

    Highlights: • The effect of stress states on the deformation behavior in the SLR was studied in the Cu{sub 54}Ni{sub 6}Zr{sub 22}Ti{sub 18} BMG alloy. • The present BMG alloy displayed different plastic stress–strain curves under tensile and compressive plastic strain states. • The calculation of the diffusivity of Cu atoms indicated that the diffusion of Cu atoms is retarded by compressive stress and accelerated by tensile stress. • The fast diffusion of Cu atoms under tensile stress caused faster crystallization leading to a fast strain-hardening during the tensile plastic deformation. -- Abstract: The effect of stress states on the deformation behavior of the Cu{sub 54}Zr{sub 22}Ti{sub 18}Ni{sub 6} bulk metallic glass (BMG) alloy was studied in the supercooled liquid region. At 723 K, Newtonian plastic flow governed the deformation during the compression test, whereas strain-hardening occurred during the tensile test. At 733 K, a fast failure was observed during tensile test. The diffusion rate of Cu atoms in the BMG alloy plays an important role in the deformation behavior. The fast diffusion of Cu atoms under the tensile stress state caused faster crystallization leading to a fast strain-hardening during the tensile plastic deformation.

  17. Promising Thermoelectric Bulk Materials with 2D Structures.

    Science.gov (United States)

    Zhou, Yiming; Zhao, Li-Dong

    2017-12-01

    Given that more than two thirds of all energy is lost, mostly as waste heat, in utilization processes worldwide, thermoelectric materials, which can directly convert waste heat to electricity, provide an alternative option for optimizing energy utilization processes. After the prediction that superlattices may show high thermoelectric performance, various methods based on quantum effects and superlattice theory have been adopted to analyze bulk materials, leading to the rapid development of thermoelectric materials. Bulk materials with two-dimensional (2D) structures show outstanding properties, and their high performance originates from both their low thermal conductivity and high Seebeck coefficient due to their strong anisotropic features. Here, the advantages of superlattices for enhancing the thermoelectric performance, the transport mechanism in bulk materials with 2D structures, and optimization methods are discussed. The phenomenological transport mechanism in these materials indicates that thermal conductivities are reduced in 2D materials with intrinsically short mean free paths. Recent progress in the transport mechanisms of Bi 2 Te 3 -, SnSe-, and BiCuSeO-based systems is summarized. Finally, possible research directions to enhance the thermoelectric performance of bulk materials with 2D structures are briefly considered. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Controlling large deformations of marginal disordered structures

    Science.gov (United States)

    Stern, Menachem; Pinson, Matthew; Carruthers, Alexandra; Chen, Elizabeth; Murugan, Arvind

    Metamaterials are typically sought to demonstrate specific responses in the non-linear deformation regime. However, analytic methods for these systems are often based on linear approximations. We find that practical questions of actuation in origami have counter-intuitive answers due to a strong mismatch between linear and non-linear theory near the special flat state, where all modes meet. Linear-non-linear mismatch generically leads to an exponential number of `dead end' folding modes, resulting in an emergent glassy energy landscape around the flat state. This landscape makes refolding of a pre-folded creased sheet much more difficult than one would expect. Conversely, borrowing results from associative memory in neuroscience, we show that structures with multiple programmed folding motions can be much easier to control than expected, as long as the flat state is avoided.

  19. Deformation compatibility control for engineering structures methods and applications

    CERN Document Server

    Zhu, Hanhua; Chen, Mengchong; Deng, Jianliang

    2017-01-01

    This book presents essential methods of deformation compatibility control, and explicitly addresses the implied conditions on the methods’ deformation compatibility. Consequently, these conditions can be considered in engineering structure design, while the conditions on stable equilibrium can be taken into account in the design method. Thus, the designed deformation and the actual deformation of the respective structure are approximately identical, guaranteeing both the flexibility of the construction material in force transmission and the equilibrium of force in the structure. Though equilibrium theory in engineering structures has been extensively studied, there has been comparatively little research on compatibility. In the limited researches available, the topics are primarily the theories and assumptions on the deformation compatibility, while few systematic works focus on the mechanical theoretical principles and methods of deformation compatibility control. As such, the flexibility of the constructi...

  20. Deformation mechanisms and resealing of damage zones in experimentally deformed cemented and un-cemented clay-rich geomaterials, at low bulk strain

    Science.gov (United States)

    Desbois, Guillaume; Urai, Janos L.; Schuck, Bernhardt; Hoehne, Nadine; Oelker, Anne; Bésuelle, Pierre; Viggiani, Gioacchino; Schmatz, Joyce; Klaver, Jop

    2017-04-01

    A microphysics-based understanding of mechanical and fluid flow properties in clay-rich geomaterials is required for extrapolating better constitutive equations beyond the laboratory's time scales, so that predictions over the long term can be made less uncertain. In this contribution, we present microstructural investigations of rocks specimens sheared in triaxial compression at low bulk strain, by using the combination of broad-ion-beam (BIB) milling and scanning electron microscopy (SEM) to infer deformation mechanisms based on microstructures imaged at sub-micron resolution. Two end-member clay-rich geomaterials from European Underground Laboratories (URL) were analysed: (i) the poorly cemented Boom Clay sediment (BC from URL at Mol/Dessel, Belgium; confining pressure [CP] = 0.375 & 1.5 MPa) and (ii) the Callovo-Oxfordian claystone (COx from the URL at Bure, France; CP = 2 & 10 MPa). Although as a first approximation the inelastic bahvior of cemented and uncemented clay-rich geomaterials can be described by similar pressure-dependent hardening plasticity models, deformed samples in this contribution show very contrasting micro-scale behaviour: microstructures reveal brittle-ductile transitional behaviour in BC, whereas deformation in COx is dominantly cataclastic. In Boom Clay, at meso-scale, shear bands exhibit characteristics that are typical of uncemented small-grained clay-rich materials deformed at high shear strains, consisting of anastomosing shears interpreted as Y- and B-shears, which bound the passively deformed microlithons. At micro- down to nano-scale, the strong shape preferential orientation of clay aggregates in the anastomosing shears is interpreted to be responsible of the shear weakness. More over, the reworking of clay aggregates during deformation contributes to the collapsing of porosity in the shear band. Ductile deformation mechanisms represented by grain-rotation, grain-sliding, bending and granular flow mechanisms are strongly involved

  1. [Bone tissue morphological structure in congenital deformations of the jaws].

    Science.gov (United States)

    Shishkanov, A V; Panin, M G; Shipkova, T P; Chumakov, A A; Komnova, Z D

    2001-01-01

    Morphological structure of bone tissue was studied in various types of congenital deformations of the jaws. Morphological changes in the bone with deformations and the severity of these disorders depended not so much on the type on the deformation, but mainly on its severity, which can be explained by a drastic increase of functional exercise because of impaired occlusion and impossibility of proper chewing. Decelerated weak restructuring of bone tissue and imperfect osteogenesis in deformed bone, similar in various types of deformations, were demonstrated on morphological material. These changes can affect the regenerative potential of the bone in operated zones.

  2. Defects and Plastic-Deformation Modes of Bulk-Metallic Glasses

    Science.gov (United States)

    Petrusenko, Yuri; Bakai, Alexander; Neklyudov, Ivan; Mikhailovskij, Igor; Bakai, Sergij; Liaw, Peter K.; Huang, Lu; Zhang, Tao

    2011-06-01

    Results of the investigation of the point-defect manifestation in the recovery kinetics of Zr41Ti14Cu12.5Ni10Be22.5 and Zr52.5Ti5Cu17.9Ni14.6Al10 bulk-metallic glasses (BMGs) irradiated with 2.5 MeV electrons at 80 K (-193.15 °C) are presented. An observation of the pronounced annealing stages at 155 K and 130 K (-118.15 °C and -143.15 °C), and 225 K (-48.15 °C), shows that irradiation generates stable point defects in BMGs. The ultrasonic vibrations (USVs) of different amplitudes were used to investigate their effects on the cluster boundaries. The Kaiser effect is chosen as a tool for examining the boundary-slip initiation and impact of vibrations on the intercluster-boundary structure. Both the acoustic-emission activity and strength decrease due to the specimen pretreatment by USV. This effect is interpreted as a result of boundary softening under the USV. The inherent tensile strength of a Zr41Ti14Cu12.5Ni10Be22.5 BMG (in atomic percent) in the as-cast state was determined by means of high-field mechanical loading using the field-ion microscopy. It was revealed that the strength is characterized by a strong size effect in a nanometer-scale range as a result of the manifestation of the structural nanoheterogeneities and, in part, the existence of the cluster boundaries.

  3. 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...

  4. Kinetics, Thermodynamics, and Structure of Bulk Metallic Glass Forming Liquids

    Science.gov (United States)

    Busch, Ralf; Gallino, Isabella

    2017-11-01

    Bulk metallic glass forming melts are viscous liquids compared with pure metals and conventional alloys. They show intermediate kinetic fragility and low thermodynamic driving force for crystallization, leading to sluggish crystallization kinetics, leaving time for good glass forming ability and bulk casting thickness. We relate the kinetics to the thermodynamics of the supercooled liquid using the Adam-Gibbs equation. The kinetic fragility is also connected to the structural changes in the liquid and can be quantitatively linked to the robustness of medium-range order in the supercooled liquid with increasing temperature. Liquid-liquid transitions from fragile behavior at high temperature to strong behavior at low temperature in the supercooled liquid and in the vicinity of the glass transition emerge as a common phenomenon.

  5. Analysis of bulk heterojunction material parameters using lateral device structures

    Science.gov (United States)

    Danielson, Eric; Ooi, Zi-En; Liang, Kelly; Morris, Joshua; Lombardo, Christopher; Dodabalapur, Ananth

    2014-01-01

    We review the key optoelectronic properties of lateral organic bulk heterojunction (BHJ) device structures with asymmetric contacts. These structures are used to develop a detailed model of charge transport and recombination properties within materials used for organic photovoltaics. They permit a variety of direct measurement techniques, such as nonlinear optical microscopy and in situ potentiometry, as well as photoconductive gain and carrier drift length studies from photocurrent measurements. We present a theoretical framework that describes the charge transport physics within these devices. The experimental results presented are in agreement with this framework and can be used to measure carrier concentrations, recombination coefficients, and carrier mobilities within BHJ materials. Lateral device structures offer a useful complement to measurements on vertical photovoltaic structures and provide a more complete and detailed picture of organic BHJ materials.

  6. 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

    , 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...

  7. 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...

  8. Structural refinement and deformation mechanisms in nanostructured metals

    DEFF Research Database (Denmark)

    Lu, K.; Hansen, Niels

    2009-01-01

    Deformation mechanisms in metals deformed to ultrahigh strains are analyzed based on a general pattern of grain subdivision down to structural scales 10 nm. The materials analyzed are medium- to high-stacking fault energy face-centered cubic and body-centered cubic metals with different loading c...

  9. Quantification of dislocation structures from anelastic deformation behaviour

    NARCIS (Netherlands)

    Arechabaleta Guenechea, Z.; van Liempt, P.; Sietsma, J.

    2016-01-01

    The pre-yield deformation behaviour (i.e., at stresses below the yield stress) of two materials, pure iron and a low-alloy steel, and its anelastic nature are analysed at room temperature, before and after the dislocation structures are varied by plastic deformation. It is shown, based on tensile

  10. Microscale Mechanical Deformation Behaviors and Mechanisms in Bulk Metallic Glasses Investigated with Micropillar Compression Experiments

    Science.gov (United States)

    Ye, Jianchao

    2011-12-01

    Over the past years of my PhD study, the focused-ion-beam (FIB) based microcompression experiment has been thoroughly investigated with respect to the small-scale deformation in metallic glasses. It was then utilized to explore the elastic and plastic deformation mechanisms in metallic glasses. To this end, micropillars with varying sample sizes and aspect ratios were fabricated by the FIB technique and subsequently compressed on a modified nanoindentation system. An improved formula for the measurement of the Young's modulus was derived by adding a geometrical prefactor to the Sneddon's solution. Through the formula, geometry-independent Young's moduli were extracted from microcompression experiments, which are consistent with nanoindentation results. Furthermore, cyclic microcompression was developed, which revealed reversible inelastic deformation in the apparent elastic regime through high-frequency cyclic loading. The reversible inelastic deformation manifests as hysteric loops in cyclic microcompression and can be captured by the Kelvin-type viscoelastic model. The experimental results indicate that the free-volume zones behave essentially like supercooled liquids with an effective viscosity on the order of 1 x 108 Pas. The microscopic yield strengths were first extracted with a formula derived based on the Mohr-Coulomb law to account for the geometrical effects from the tapered micropillar and the results showed a weak size effect on the yield strengths of a variety of metallic-glass alloys, which can be attributed to Weibull statistics. The nature of the yielding phenomenon was explored with the cyclic micro-compression approach. Through cyclic microcompression of a Zr-based metallic glass, it can be demonstrated that its yielding stress increases at higher applied stress rate but its yielding strain is kept at a constant of ~ 2%. The room-temperature post-yielding deformation behavior of metallic glasses is characterized by flow serrations, which were

  11. Deformed configurations, band structures and spectroscopic ...

    Indian Academy of Sciences (India)

    2014-03-20

    Mar 20, 2014 ... the deformed solution C (band D2). The intrinsic configurations of various excited bands are determined by the orbits near the Fermi surfaces. In figure 2, we show the orbits near the Fermi surfaces for the uncon- strained and constrained HF solutions of 82Ge. For the 'almost' spherical solution, the.

  12. Iron phosphate glasses: Bulk properties and atomic scale structure

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, Kitheri; Stennett, Martin C.; Hyatt, Neil C.; Asuvathraman, R.; Dube, Charu L.; Gandy, Amy S.; Govindan Kutty, K. V.; Jolley, Kenny; Vasudeva Rao, P. R.; Smith, Roger

    2017-10-01

    Bulk properties such as glass transition temperature, density and thermal expansion of iron phosphate glass compositions, with replacement of Cs by Ba, are investigated as a surrogate for the transmutation of 137Cs to 137Ba, relevant to the immobilisation of Cs in glass. These studies are required to establish the appropriate incorporation rate of 137Cs in iron phosphate glass. Density and glass transition temperature increases with the addition of BaO indicating the shrinkage and reticulation of the iron phosphate glass network. The average thermal expansion coefficient reduces from 19.8 × 10-6 K-1 to 13.4 × 10-6 K-1, when 25 wt. % of Cs2O was replaced by 25 wt. % of BaO in caesium loaded iron phosphate glass. In addition to the above bulk properties, the role of Ba as a network modifier in the structure of iron phosphate glass is examined using various spectroscopic techniques. The FeII content and average coordination number of iron in the glass network was estimated using Mössbauer spectroscopy. The FeII content in the un-doped iron phosphate glass and barium doped iron phosphate glasses was 20, 21 and 22 ± 1% respectively and the average Fe coordination varied from 5.3 ± 0.2 to 5.7 ± 0.2 with increasing Ba content. The atomic scale structure was further probed by Fe K-edge X-ray absorption spectroscopy. The average coordination number provided by extended X-ray absorption fine structure spectroscopy and X-ray absorption near edge structure was in good agreement with that given by the Mössbauer data.

  13. Description of soft sediment deformational structure of the Campano ...

    African Journals Online (AJOL)

    These soft sediment deformational structures includes: simple internal cusps, which occur wide spread across a single bed or intermittently across several beds, and slump structures that are represented by complex recumbent folds and concave upwards structures. These structures are proxy to syn-depositional energy ...

  14. 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.

  15. Formation of disorientations in dislocation structures during plastic deformation

    DEFF Research Database (Denmark)

    Pantleon, W.

    2002-01-01

    Disorientations developing during plastic deformation in dislocation structures are investigated. Based on expected mechanisms for the formation of different types of dislocation boundaries (statistical trapping of dislocations or differently activated slip systems) the formation of the disorient......Disorientations developing during plastic deformation in dislocation structures are investigated. Based on expected mechanisms for the formation of different types of dislocation boundaries (statistical trapping of dislocations or differently activated slip systems) the formation...

  16. Long-Term Deformations of Concrete Structures

    OpenAIRE

    A. Brahma

    2015-01-01

    Drying is a phenomenon that accompanies the hardening of hydraulic materials. This study is concerned the modelling of drying shrinkage of the hydraulic materials and the prediction of the rate of spontaneous deformations of hydraulic materials during hardening. The model developed takes consideration of the main factors affecting drying shrinkage. There was agreement between drying shrinkage predicted by the developed model and experimental results. In last we show that ...

  17. Structural effects of shot-peening in bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Mear, F.O., E-mail: francois.mear@univ-lille1.f [University of Cambridge, Department of Materials Science and Metallurgy, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Doisneau, B.; Yavari, A.R. [SIMaP-CNRS UA29, Domaine Universitaire BP 75, Saint Martin d' Heres 38402 (France); Greer, A.L. [University of Cambridge, Department of Materials Science and Metallurgy, Pembroke Street, Cambridge CB2 3QZ (United Kingdom)

    2009-08-26

    Shot-peening induces surface compressive stresses in bulk metallic glass components, improving their plasticity. Structural changes in the peened surface of fully glassy and partially crystalline Zr{sub 55}Al{sub 10}Cu{sub 30}Ni{sub 5} are studied by X-ray diffraction, transmission electron microscopy and differential scanning calorimetry. An earlier study is extended by examining the effect of sample temperature. While fully glassy samples show no phase change under peening, partially crystalline samples show either amorphization or crystallization depending on temperature. Peening can induce very large stored energy in metallic glasses rendering them susceptible to crystallization below room temperature, a result which may be relevant for improving the plasticity of these materials.

  18. Control and large deformations of marginal disordered structures

    Science.gov (United States)

    Murugan, Arvind; Pinson, Matthew; Chen, Elizabeth

    Designed deformations, such as origami patterns, provide a way to make easily controlled mechanical metamaterials with tailored responses to external forces. We focus on an often overlooked regime of origami - non-linear deformations of large disordered origami patterns with no symmetries. We find that practical questions of control in origami have counterintuitive answers, because of intimate connections to spin glasses and neural networks. For example, 1 degree of freedom origami structures are actually difficult to control about the flat state with a single actuator; the actuator is thrown off by an exponential number of `red herring' zero modes for small deformations, all but one of which disappear at larger deformations. Conversely, structures with multiple programmed motions are much easier to control than expected - in fact, they are as easy to control as a dedicated single-motion structure if the number of programmed motions is below a threshold (`memory capacity').

  19. The bulk Higgs in the Deformed RS Model arXiv

    CERN Document Server

    Mahmoudi, F.; Sridhar, K.

    The Randall-Sundrum model with a deformed metric can generate light Kaluza-Klein (KK) Higgs modes consistent with the electroweak precision analysis for a certain range of parameters. The first KK mode of the Higgs ($h_{1}$) in such a model could lie in the mass range varying from 800 GeV to 1.3 TeV. We find that the $h_{1}$ is gaugephobic and decays dominantly into a $t\\bar{t}$ pair. The search strategy for $h_{1}$ decaying to $t\\bar{t}$ at the Large Hadron Collider (LHC) in this low mass range has been studies. We have used substructure tools to suppress the large QCD background associated with this channel. We find that $h_{1}$ can be probed at the LHC.

  20. 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

  1. Deformation-induced dehydration structures in the Nankai accretionary prism

    Science.gov (United States)

    Famin, V.; Byrne, T.; Lewis, J. C.; Kanagawa, K.; Behrmann, J.; Iodp 314/315/316 Scientists, E.

    2008-12-01

    This study investigates the chemical changes caused by deformation in the hanging wall of a major, probably seismogenic thrust fault in the Kumano forearc basin, Nankai Trough. In cores from IODP Expedition 315 (site C0001), the clay sediments display numerous deformation structures including tilted beddings, decimeter scale faults and shear zones with normal or thrust offsets, and clusters of parallel curviplanar veins interpreted as earthquake-induced dewatering structures. Curviplanar veins are often observed to merge into small oblique shear zones with millimeter offsets, or to branch on larger shear zones with a ~30° angle. This suggests that some shear zones may form by the coalescence of veins. Curviplanar veins and shear zones appear darker than the surrounding clay at the macroscopic observation scale, and brighter and therefore denser under CT-scan imaging. At the micro-scale, clay has a preferred crystallographic orientation in the deformation structures and no preferred orientation outside. Electron probe micro-analysis reveals that the dark material has a higher sum of major elements (65-80 wt%), i.e. a lower volatile content (assumed to be mostly water) than the host sediment (50-60 wt%). All the major elements are equally enriched in proportion to the volatile depletion. Mass balance calculation indicates that a 20-30 wt% water loss is required to account for chemical change in the deformation microstructures. The water loss may be due to clay dehydration or to pore collapse. Shear zones are equally dehydrated as the curviplanar veins from the mass balance standpoint. In 1 m3 of sediment, a deformed volume of 1 % should produce about 6.2 L of water. Given the low permeability of the sediment, dehydration may increase the pore pressure and enhance further deformation. Deformation localization would be self-sustained by fluid overpressure, suggesting that dewatering veins may evolve into larger deformation structures after an earthquake.

  2. The structure and phase composition of welded joint after deformation

    Science.gov (United States)

    Smirnov, Aleksander; Popova, Natalya; Ozhiganov, Eugeniy; Nikonenko, Elena; Ababkov, Nikolay; Kalashnikov, Mark; Koneva, Nina; Kozlov, Eduard

    2017-01-01

    The paper addresses the issue of the structure and phase composition of welded joint and focuses on their investigation after plastic deformation. The contribution of internal stresses to the formation of phase composition and fine structure of welded joint is shown herein. Electrode welding is used to obtain welded joint in St3 steel. Specimens are subjected to a quasi-static tensile deformation ranging from 0 to 5% under 370 MPa loading. TEM investigations on thin foil specimens allow studying the structure and phase composition within the heat-affected zone at 1 mm distance from base material and 0.5 mm from welding material. The degree of plastic deformation is shown for both base and welding materials and includes their morphology, phase composition, defect structure and its parameters. Long-range stresses are divided into plastic and elastic. Plastic deformation has no qualitative effect on the material structure, however, it modifies its quantitative parameters. With the increase of deformation degree, the perlite component becomes more imperfect and transforms, first, to a fractured perlite and then to ferrite, thereby decreasing the volume ratio of perlite. Polarization of the dislocation structure is observed. The amplitude of internal stress fields grows. Unlike the shear stresses, long-range stresses manifest their intensive growth. The elastic component makes the major contribution to the long-range stresses resulting in the formation of microcracks.

  3. Two-fold origin of the deformation-induced ferromagnetism in bulk Fe{sub 60}Al{sub 40} (at.%) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Menendez, E; Surinach, S; Baro, M D [Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Sort, J [Institucio Catalana de Recerca i Estudis Avancats (ICREA) and Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Liedke, M O; Fassbender, J [Institute of Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf, PO Box 510119, D-01314 Dresden (Germany); Nogues, J [Institucio Catalana de Recerca i Estudis Avancats (ICREA) and Institut Catala de Nanotecnologia, Edifici CM7, Campus Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain)], E-mail: jordi.sort@uab.es

    2008-01-15

    The transition from the atomically ordered B2-phase to the chemically disordered A2-phase and the concomitant deformation-induced ferromagnetism have been investigated in bulk polycrystalline Fe{sub 60}Al{sub 40} (at.%) alloys subjected to compression processes. A detailed correlation between structural, magnetic and mechanical properties reveals that the generated ferromagnetism depends on the stress level but is virtually independent of the loading rate. The mechanisms governing the induced ferromagnetism also vary as the stress level is increased. Namely, in the low-stress regime both lattice cell expansion and atomic intermixing play a role in the induced ferromagnetic behavior. Conversely, lattice expansion seems to become the main mechanism contributing to the generated ferromagnetism in the high-stress regime. Furthermore, a correlation is also observed between the order-disorder transition and the mechanical hardness. Hence, a combination of magnetic and mechanical measurements can be used, in synergetic manner, to investigate this deformation-induced phase transition.

  4. Towards highs performance bulk thermoelectric materials with enhanced mechanical properties by Severe Plastic Deformation (SPD)

    OpenAIRE

    Santamaría Regueiro, J.A.(Jon Ander); Gil Sevillano, J. (Javier); Alkorta Barragan, J. (Jon)

    2016-01-01

    Nowadays, one of the most promising strategies to produce highly efficient thermoelectric (TE) materials is to reduce the lattice thermal conductivity by introducing phonon scattering centres (such as submicron sized grain boundaries, second-phase nano-particles, and point defects) at different length scales. For highly anisotropic crystals such as Bi2Te3-based thermoelectrics, the combination of nanosized grain structures (to improve phonon scattering) together with strong crystallographic t...

  5. Rate-dependent serrated flow and plastic deformation in Ti45Zr16Be20Cu10Ni9 bulk amorphous alloy during nanoindentation

    Directory of Open Access Journals (Sweden)

    Dinesh Kumar Misra, Sung Woo Sohn, Won Tae Kim and Do Hyang Kim

    2008-01-01

    Full Text Available The plastic deformation of Ti45Zr16Be20Cu10Ni9 bulk metallic glass has been investigated by nanoindentation performed with loads ranging from 10 to 200 mN in a wide range of loading rates. The plastic flow in the alloy exhibited conspicuous serrations at low loading rates. The serrations, however, became less prominent as the rate of indentation increased. Atomic force microscopy showed a significant pile-up of materials around the indents, indicating that a highly localized plastic deformation occurred under nanoindentation. The possible mechanism governing the plastic deformation in bulk metallic glass specimens is tentatively discussed in terms of strain-induced free volume.

  6. 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.

  7. Electronic spectra of structurally deformed lutein.

    Science.gov (United States)

    Macernis, Mindaugas; Sulskus, Juozas; Duffy, Christopher D P; Ruban, Alexander V; Valkunas, Leonas

    2012-10-11

    Quantum chemical calculations have been employed for the investigation of the lowest excited electronic states of lutein, with particular reference to its function within light harvesting antenna complexes of higher plants. Through comparative analysis obtained by using different methods based on gas-phase calculations of the spectra, it was determined that variations in the lengths of the long C-C valence bonds and the dihedral angles of the polyene chain are the dominant factors in determining the spectral properties of Lut 1 and Lut 2 corresponding to the deformed lutein molecules taken from crystallographic data of the major pigment-protein complex of photosystem II. By MNDO-CAS-CI method, it was determined that the two singlet B(u) states of lutein (nominally 1B(u)(-)* and 1B(u)(+)) arise as a result of mixing of the canonical 1B(u)(-) and 1B(u)(+) states of the all-trans polyene due to the presence of the ending rings in lutein. The 1B(u)(-)* state of lutein is optically allowed, while the 1B(u)(-) of a pure all-trans polyene chain is optically forbidden. As demonstrated, the B(u) states are much more sensitive to minor distortions of the conjugated chain due to mixing of the canonical states, resulting in states of poorly defined particle-hole symmetry. Conversely, the A(g) states are relatively robust with respect to geometric distortion, and their respective inversion and particle-hole symmetries remain relatively well-defined.

  8. Effect of Marangoni stress on the bulk rheology of a dilute emulsion of surfactant-laden deformable droplets in linear flows

    Science.gov (United States)

    Mandal, Shubhadeep; Das, Sayan; Chakraborty, Suman

    2017-11-01

    In the present study, we analytically investigate the deformation and bulk rheology of a dilute emulsion of surfactant-laden droplets suspended in linear flows. We use an asymptotic approach to determine the effect of surfactant distribution on the deformation of an isolated droplet as well as the effective shear and extensional viscosity for a dilute emulsion. The nonuniform distribution of surfactants due to the bulk flow results in the generation of a Marangoni stress, which affects both the deformation as well as the bulk rheology of the emulsion. The present analysis is done for the limiting case when the surfactant transport is dominated by the surface diffusion relative to surface convection. As an example, we have used two commonly encountered bulk flows, namely, uniaxial extensional flow and simple shear flow. With the assumption of negligible inertial forces present in either of the phases, we show that both the surfactant concentration on the droplet surface as well as the ratio of viscosity of the droplet phase with respect to the suspending fluid has a significant effect on the droplet deformation as well as the bulk rheology. It is seen that increase in the nonuniformity in surfactant distribution on the droplet surface results in a higher droplet deformation and a higher effective viscosity for either of the linear flows considered. The effect of surfactant distribution on effective viscosity is insignificant for highly viscous droplets. For the case of simple shear flow, surfactant distribution is found to have no effect on the inclination angle. However, a higher viscosity ratio predicts the droplet to be more aligned toward the direction of flow. First and second normal stress differences are present for the case of a simple shear flow, of which the former is found to increase with nonuniformity in surfactant distribution, whereas the later remains unaffected.

  9. 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.

  10. QuikForm: Intelligent deformation processing of structural alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bourcier, R.J.; Wellman, G.W.

    1994-09-01

    There currently exists a critical need for tools to enhance the industrial competitiveness and agility of US industries involved in deformation processing of structural alloys. In response to this need, Sandia National Laboratories has embarked upon the QuikForm Initiative. The goal of this program is the development of computer-based tools to facilitate the design of deformation processing operations. The authors are currently focusing their efforts on the definition/development of a comprehensive system for the design of sheet metal stamping operations. The overall structure of the proposed QuikForm system is presented, and the focus of their thrust in each technical area is discussed.

  11. Deformed microbial mat structures in a semiarid temperate coastal setting

    Science.gov (United States)

    Cuadrado, Diana G.; Pan, Jerónimo; Gómez, Eduardo A.; Maisano, Lucía

    2015-07-01

    This study focuses on sedimentary structures formed by microbial consortia, in a particular coastal setting, an ancient tidal channel, separated from the ocean by a sandy spit and connected by a blind tidal channel at the opposite end. Most studies in modern and ancient environments consider water movement as the triggering mechanism acting in the formation and deformation of sedimentary structures. As such, the paper documents the presence of several microbial structures such as shrinkage cracks, flip-over mats, microbial chips, and multidirectional ripples which are related to tidal processes, while bulges and gas domes structures are formed after occasional inundation events. However, the more conspicuous structures covering a great area at the study site are folds and roll-ups, the product of deformation of microbially induced structures by the action of sporadic spring-tidal currents due to strong winds. Therefore, the objective of this research is to document modern sedimentary structures in a coastal area and to provide a mechanistic explanation for their formation, based on the interplaying effects of the moisture variation and high shear stress. Also, several microbial sedimentary structures are distinguished throughout vertical sediment cores, such as microbial chips, detached mat, sponge fabrics, tears, and concentric structures, which are identified in a sedimentary profile. Through the recognition and interpretation of modern sedimentary deformation structures, this study contributes empirical tools for the reconstruction of analogous paleoenvironments in fossil studies.

  12. Structures in an anhydrite layer embedded in halite matrix: Results from thermomechanical experiments under bulk plain strain

    Science.gov (United States)

    Mertineit, M.; Zulauf, G.; Peinl, M.; Zanella, F.; Bornemann, O.

    2009-04-01

    Anhydrite layers from Gorleben salt dome, embedded in a halite matrix from Asse salt dome, both northern Germany, were deformed under bulk plain strain using a thermomechenical apparatus (Zulauf et al., 2007, 2009). The initial layer thickness Hi ranges from 0.85 to 2.5 mm. Further deformation conditions were as follows: T =345˚ C, max=4.59 MPa, ezmax=-40%, Ä-=2*10-7s-1. During the deformation process, load cells record the stress along Y and Z. The displaced material could escape in X. The deformed samples were scanned using a computer tomograph at the Universitätsklinikum Frankfurt/Main. The CT data allow the generation of 3D-modells using the software Smoooth. We deformed six samples with the layer (S) perpendicular to the X-axis and four samples with the layer perpendicular to the Z-axis. Depending on the orientation of the layer (S⊥X or S⊥Z), the expected structures should be folds or boudins, respectively, the geometry of which should strongly depend on Hi. In cases were the layer was orientated parallel to the shortening axis (S⊥X), the anhydrite layer shows Mohr-Coulomb fractures. The fracture walls were thrust on top of each other. The space between hanging and foot wall is filled with salt. The angle between the fractures and the YZ-plain ranges from 10˚ to 25˚ , rarely up to 70˚ , dependent on the finite strain. In thin layers (Hi=0.85 and 1 mm) rarely non-cylindrical folds developed. In both cases (S⊥X and S⊥Z) the layer thickness did not significantly change during deformation. In cases were the layer was orientated perpendicular to the shortening axis (S⊥Z) boudins developed by extensional fracture. The number of boudins and their size depend strongly on the initial layer thickness Hi. With increasing layer thickness Hi the width of boudins Wa increases linearly. Wa = -0.2 + 1.4 * Hi (1) This relation between Hi and Wa is further compatible with equation (16.4) of Price and Cosgrove (1990) which also

  13. 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.

  14. High-energy photoemission spectroscopy for investigating bulk electronic structures of strongly correlated systems

    Energy Technology Data Exchange (ETDEWEB)

    Sekiyama, Akira, E-mail: sekiyama@mp.es.osaka-u.ac.jp [Division of Materials Physics, Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531, Osaka (Japan); SPring-8/RIKEN, Sayo 679-5148, Hyogo (Japan)

    2016-04-15

    Progress of high-energy photoemission spectroscopy for investigating the bulk electronic structures of strongly correlated electron systems is reviewed. High-resolution soft X-ray photoemission has opened the door for revealing the bulk strongly correlated spectral functions overcoming the surface contributions. More bulk-sensitive hard X-ray photoemission spectroscopy (HAXPES) enables us to study the electronic structure with negligible surface contribution. The recent development of the polarization-dependent HAXPES is also described in this short review.

  15. Evaluation of soft sediment deformation structures along the Fethiye ...

    Indian Academy of Sciences (India)

    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 ...

  16. Characteristics of aluminum alloy microplastic deformation in different structural states

    Energy Technology Data Exchange (ETDEWEB)

    Seregin, G.V.; Efimenko, L.L.; Leonov, M.V. [Novosibirsk Pedagogical Inst. (Russian Federation)

    1995-07-01

    The solution to the problem of improving the mechanical properties (including cyclic strength) of structural materials is largely dependent on our knowledge of the laws governing the development of microplastic deformations in them. The effect of heat and mechanical treatment on the elastoplastic properties and fatigue resistance of the commercial aluminum alloys AK4-1 and D16 is analyzed.

  17. Evaluation of soft sediment deformation structures along the Fethiye ...

    Indian Academy of Sciences (India)

    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 ...

  18. Formation of diapiric structure in the deformation zone, central ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 111; Issue 1. Formation of diapiric structure in the deformation zone, central Indian Ocean: A model from gravity and seismic reflection data. K S Krishna D Gopala Rao Yu P Neprochnov. Volume 111 Issue 1 March 2002 pp 17-28 ...

  19. Dislocation Structures in Creep-deformed Polycrystalline MgO

    DEFF Research Database (Denmark)

    Bilde-Sørensen, Jørgen

    1972-01-01

    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...

  20. Band structure in bulk entanglement spectrum of quantum Hall state

    Science.gov (United States)

    Lu, Chi-Ken; Chiou, D.-W.; Lin, F.-L.

    We study the bulk entanglement spectrum of integer quantum Hall state with a symmetric checkerboard partition of space. By reformulating the correlation matrix in a guiding center representation, we show that the problem is mapped to a two-dimensional lattice with unit vector determined by the field and partition grid. The bulk entanglement spectrum shows the particle-hole symmetry and the band touching, whic are related to the dual symmetry of partition and the Chern number, respectively. The work was supported by Ministry of Science and Technology Taiwan.

  1. Definitions of Resistance and Deformation Capacity for Non-Sway Steel and Composite Structures

    NARCIS (Netherlands)

    Steenhuis, C.M.; Vrouwenvelder, A.C.W.M.; Van Herwijnen, F.; Snijder, H.H.

    2002-01-01

    Resistance, stiffness and deformation capacity are three characteristics describing the behaviour of (statically loaded) structures. The stiffness relates mostly to the serviceability of the structure. The resistance and deformation capacity relate to the safety of the structure. Nowadays, the

  2. Bulk Nanostructured Materials

    Science.gov (United States)

    Koch, C. C.; Langdon, T. G.; Lavernia, E. J.

    2017-11-01

    This paper will address three topics of importance to bulk nanostructured materials. Bulk nanostructured materials are defined as bulk solids with nanoscale or partly nanoscale microstructures. This category of nanostructured materials has historical roots going back many decades but has relatively recent focus due to new discoveries of unique properties of some nanoscale materials. Bulk nanostructured materials are prepared by a variety of severe plastic deformation methods, and these will be reviewed. Powder processing to prepare bulk nanostructured materials requires that the powders be consolidated by typical combinations of pressure and temperature, the latter leading to coarsening of the microstructure. The thermal stability of nanostructured materials will also be discussed. An example of bringing nanostructured materials to applications as structural materials will be described in terms of the cryomilling of powders and their consolidation.

  3. Polycrystal deformation and single crystal deformation: Dislocation structure and flow stress in copper

    DEFF Research Database (Denmark)

    Huang, X.; Borrego, A.; Pantleon, W.

    2001-01-01

    The relation between the polycrystal deformation and single crystal deformation has been studied for pure polycrystalline copper deformed in tension. The dislocation microstructure has been analyzed for grains of different orientation by transmission electron microscopy (TEM) and three types...

  4. EARTHQUAKE-INDUCED DEFORMATION STRUCTURES AND RELATED TO EARTHQUAKE MAGNITUDES

    Directory of Open Access Journals (Sweden)

    Savaş TOPAL

    2003-02-01

    Full Text Available Earthquake-induced deformation structures which are called seismites may helpful to clasify the paleoseismic history of a location and to estimate the magnitudes of the potention earthquakes in the future. In this paper, seismites were investigated according to the types formed in deep and shallow lake sediments. Seismites are observed forms of sand dikes, introduced and fractured gravels and pillow structures in shallow lakes and pseudonodules, mushroom-like silts protruding laminites, mixed layers, disturbed varved lamination and loop bedding in deep lake sediments. Earthquake-induced deformation structures, by benefiting from previous studies, were ordered according to their formations and earthquake magnitudes. In this order, the lowest eartquake's record is loop bedding and the highest one is introduced and fractured gravels in lacustrine deposits.

  5. Coeval brittle and ductile structures associated with extreme deformation partitioning in a multilayer sequence

    Science.gov (United States)

    Druguet, Elena; Alsop, G. Ian; Carreras, Jordi

    2009-05-01

    An investigation on the effects of a strong rheological contrast in the deformation of layered anisotropic rocks is presented. The study focuses on the geometric and kinematic analysis of complex structures developed within and adjacent to a thin marble-metapsammite multilayer unit from the Cap de Creus tectonometamorphic belt (NE Spain). Zones of high ductile strain localise in the marble layers, which exhibit complex folds, whereas metapsammites show mostly brittle (boudinage) structures. These structures strongly contrast with coeval retrogressive discrete shear zones developed in the surrounding migmatitic schists. The extreme strain partitioning is due to the rheological contrast between different lithological layers. In addition, the specific orientation of this multilayer unit induces a reversal of local kinematics with regard to bulk kinematics. Consequently, caution should be exercised when interpreting regional tectonics in highly partitioned domains associated with rheological heterogeneities.

  6. Deformation, Ecosystem Structure, and Dynamics of Ice (DESDynI)

    Science.gov (United States)

    Donnellan, Andrea; Rosen, Paul; Ranson, Jon; Zebker, Howard

    2008-01-01

    The National Research Council Earth Science Decadal Survey, Earth Science Applications from Space, recommends that DESDynI (Deformation, Ecosystem Structure, and Dynamics of Ice), an integrated L-band InSAR and multibeam Lidar mission, launch in the 2010- 2013 timeframe. The mission will measure surface deformation for solid Earth and cryosphere objectives and vegetation structure for understanding the carbon cycle. InSAR has been used to study surface deformation of the solid Earth and cryosphere and more recently vegetation structure for estimates of biomass and ecosystem function. Lidar directly measures topography and vegetation structure and is used to estimate biomass and detect changes in surface elevation. The goal of DESDynI is to take advantage of the spatial continuity of InSAR and the precision and directness of Lidar. There are several issues related to the design of the DESDynI mission, including combining the two instruments into a single platform, optimizing the coverage and orbit for the two techniques, and carrying out the science modeling to define and maximize the scientific output of the mission.

  7. Intermediate size inducer pump - structural analysis and transient deformation studies

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, T.K.; Nishizaka, J.N.

    1979-05-01

    This report summarizes the structural and thermal transient deformation analysis of the Intermediate Size Inducer Pump. The analyses were performed in accordance to the requirements of N266ST310001, the specification for the ISIP. Results of stress analysis indicate that the thermal transient stress and strain are within the stress strain limits of RDT standard F9-4 which was used as a guide.

  8. Transition of Temporal Scaling Behavior in Percolation Assisted Shear-branching Structure during Plastic Deformation

    Science.gov (United States)

    Ren, Jingli; Chen, Cun; Wang, Gang; Liaw, Peter K.

    2017-03-01

    This paper explores the temporal scaling behavior induced shear-branching structure in response to variant temperatures and strain rates during plastic deformation of Zr-based bulk metallic glass (BMG). The data analysis based on the compression tests suggests that there are two states of shear-branching structures: the fractal structure with a long-range order at an intermediate temperature of 223 K and a larger strain rate of 2.5 × 10-2 s-1 the disordered structure dominated at other temperature and strain rate. It can be deduced from the percolation theory that the compressive ductility, ec, can reach the maximum value at the intermediate temperature. Furthermore, a dynamical model involving temperature is given for depicting the shear-sliding process, reflecting the plastic deformation has fractal structure at the temperature of 223 K and strain rate of 2.5 × 10-2 s-1.

  9. The bulk composition, mineralogy and internal structure of Mars

    Science.gov (United States)

    Longhi, John; Knittle, Elise; Holloway, John R.; Waenke, Heinrich

    1992-01-01

    A bulk composition for Mars is derived to a pressure-dependent mineralogy. The density distribution of the present model is compared with density distributions derived from the global gravity field. It is argued that the uppermost Martian mantle is likely to be dominated by olivine and orthopyroxene, as is the earth's upper mantle, although the Martian mantle has a lower MgO/(MgO + FeO) ratio (0.74 vs 0.89). The olivine-peridotite layer extends to a depth of 900 to 1100 km where the transition to silicate spinel begins. Calculations of the high-pressure liquidus and solidus temperatures indicate that for the case of a molten core the minimum temperature at the core-mantle boundary is about 2000 K, whereas for the case of a solid core the maximum temperature is about 1800 K. Summation of the masses in the various layers of Mars yields a value of 0.353 for the dimensionless moment of inertia, which is intermediate between the generally accepted value of 0.365 and the value of 0.345 predicated on a nonaxisymmetric distribution of mass about the Tharsis plateau.

  10. Structure and properties of copper after large strain deformation

    Energy Technology Data Exchange (ETDEWEB)

    Rodak, Kinga; Molak, Rafal M.; Pakiela, Zbigniew

    2010-05-15

    Structure and properties of Cu in dependence on strain (from {epsilon}{proportional_to} 0.9 to {epsilon}{proportional_to} 15) during multi-axial compression processing at room temperature was investigated. The evolution of dislocation structure, misorientation distribution and crystallite size were observed by using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) equipment with electron back scattered diffraction (EBSD) facility. The mechanical properties of yield strength (YS), ultimate tensile strength (UTS) and uniform elongation was performed on MTS QTest/10 machine equipped with digital image correlation method (DIC). The structure-flow stress relationship of multi-axial compression processing material at strains {epsilon}{proportional_to} 3.5 and {epsilon}{proportional_to} 5.5 is discussed. It is found that processing does not produce any drastic changes in deformation structure and the microstructural refinement is slow. These results indicate that dynamic recrystallization plays an important role during multi-axial compression process in this range of deformation (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. 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.

  12. A holographic model for pseudogap in BCS-BEC crossover (I): Pairing fluctuations, double-trace deformation and dynamics of bulk bosonic fluid

    Science.gov (United States)

    DeWolfe, Oliver; Henriksson, Oscar; Wu, Chaolun

    2017-12-01

    We build a holographic model for the pairing fluctuation pseudogap phase in fermionic high temperature superconductivity/superfluidity based on the BCS-BEC crossover scenario. The pseudogap originates from incoherent Cooper pairing and has been observed in recent cold atom experiments. The strength of Cooper pairing and hence the BCS-BEC crossover is controlled by an effective 4-Fermi interaction and we argue that the double-trace deformation for charged scalar operator is a close analog in large N field theories. We employ the double-trace deformed Abelian Higgs model of holographic superconductors and propose that the incoherent fluctuations of the charged scalar in the bulk is the holographic dual of the fluctuating Cooper pairs. Using a Madelung transformation and the velocity-potential formalism, we develop a quantum fluid dynamics as an effective theory for these bulk fluctuations. The new fluid dynamics takes care of the boundary conditions required by AdS/CFT and encodes the vacuum polarization effect in curved spacetime. The pseudogap in conductivity can be related to the plasma oscillation of this bulk fluid.

  13. Shear deformation plate continua of large double layered space structures

    Science.gov (United States)

    Hefzy, Mohamed Samir; Nayfeh, Adnan H.

    1986-01-01

    A simple method is presented to model large rigid-jointed lattice structures as continuous elastic media with couple stresses using energy equivalence. In the analysis, the transition from the discrete system to the continuous media is achieved by expanding the displacements and the rotations of the nodal points in a Taylor series about a suitable chosen origin. The strain energy of the continuous media with couple stresses is then specialized to obtain shear deformation plate continua. Equivalent continua for single layered grids, double layered grids, and three-dimensional lattices are then obtained.

  14. Modeling adsorption properties of structurally deformed metal-organic frameworks using structure-property map.

    Science.gov (United States)

    Jeong, WooSeok; Lim, Dae-Woon; Kim, Sungjune; Harale, Aadesh; Yoon, Minyoung; Suh, Myunghyun Paik; Kim, Jihan

    2017-07-25

    Structural deformation and collapse in metal-organic frameworks (MOFs) can lead to loss of long-range order, making it a challenge to model these amorphous materials using conventional computational methods. In this work, we show that a structure-property map consisting of simulated data for crystalline MOFs can be used to indirectly obtain adsorption properties of structurally deformed MOFs. The structure-property map (with dimensions such as Henry coefficient, heat of adsorption, and pore volume) was constructed using a large data set of over 12000 crystalline MOFs from molecular simulations. By mapping the experimental data points of deformed SNU-200, MOF-5, and Ni-MOF-74 onto this structure-property map, we show that the experimentally deformed MOFs share similar adsorption properties with their nearest neighbor crystalline structures. Once the nearest neighbor crystalline MOFs for a deformed MOF are selected from a structure-property map at a specific condition, then the adsorption properties of these MOFs can be successfully transformed onto the degraded MOFs, leading to a new way to obtain properties of materials whose structural information is lost.

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

    Energy Technology Data Exchange (ETDEWEB)

    Stoica, Mihai, E-mail: m.stoica@ifw-dresden.de; Scudino, Sergio [IFW Dresden, Institute for Complex Materials, Helmholtzstr. 20, D-01069 Dresden (Germany); Bednarčik, Jozef [Deutsches Elektronen-Synchrotron (DESY), FS-PE Group, Notkestr. 85, D-22607 Hamburg (Germany); Kaban, Ivan; Eckert, Jürgen [IFW Dresden, Institute for Complex Materials, Helmholtzstr. 20, D-01069 Dresden (Germany); TU Dresden, Institute of Materials Science, D-01062 Dresden (Germany)

    2014-02-07

    By adding 0.5 at. % Cu to the strong but brittle [(Fe{sub 0.5}Co{sub 0.5}){sub 0.75}Si{sub 0.05}B{sub 0.20}]{sub 96}Nb{sub 4} 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.

  16. Effect of Hafnium and Zirconium to Glass Forming Ability, Thermal Stability, Plasticity Deformation and Crystallization of Ni-Free Pentabasic Ti-Based Bulk Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Oak J.J.

    2017-06-01

    Full Text Available The newly designed Ti-based bulk metallic glass (BMG in which case of fracture behavior was observed 1990MPa to compressive strength with a wide plastic deformation around 7% after process of elastic deformation. This phenomenon can be compared with those of Ti-based alloys and other Ti-based BMGs and indicates high potential to be applied in use. It was evaluated the Ti-based BMG for thermal stability that the reduced glass parameters, ΔTx, Trg and γ, are 79K, 0.50 and 0.38, respectively. In addition, it reveals high activation energies for crystallization in which are estimated to Ex1 = 291.77 ±9.71 kJ/mol, Ex2 = 588.77 ±28.88 kJ/mol and Ex3 = 330.26 ±3.61 kJ/mol on kissinger plotting in this study.

  17. 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

  18. Deformable structure registration of bladder through surface mapping.

    Science.gov (United States)

    Xiong, Li; Viswanathan, Akila; Stewart, Alexandra J; Haker, Steven; Tempany, Clare M; Chin, Lee M; Cormack, Robert A

    2006-06-01

    Cumulative dose distributions in fractionated radiation therapy depict the dose to normal tissues and therefore may permit an estimation of the risk of normal tissue complications. However, calculation of these distributions is highly challenging because of interfractional changes in the geometry of patient anatomy. This work presents an algorithm for deformable structure registration of the bladder and the verification of the accuracy of the algorithm using phantom and patient data. In this algorithm, the registration process involves conformal mapping of genus zero surfaces using finite element analysis, and guided by three control landmarks. The registration produces a correspondence between fractions of the triangular meshes used to describe the bladder surface. For validation of the algorithm, two types of balloons were inflated gradually to three times their original size, and several computerized tomography (CT) scans were taken during the process. The registration algorithm yielded a local accuracy of 4 mm along the balloon surface. The algorithm was then applied to CT data of patients receiving fractionated high-dose-rate brachytherapy to the vaginal cuff, with the vaginal cylinder in situ. The patients' bladder filling status was intentionally different for each fraction. The three required control landmark points were identified for the bladder based on anatomy. Out of an Institutional Review Board (IRB) approved study of 20 patients, 3 had radiographically identifiable points near the bladder surface that were used for verification of the accuracy of the registration. The verification point as seen in each fraction was compared with its predicted location based on affine as well as deformable registration. Despite the variation in bladder shape and volume, the deformable registration was accurate to 5 mm, consistently outperforming the affine registration. We conclude that the structure registration algorithm presented works with reasonable accuracy and

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

    Energy Technology Data Exchange (ETDEWEB)

    Lollobrigida, V. [Dipartimento di Scienze, Università Roma Tre, I-00146 Rome (Italy); Dipartimento di Matematica e Fisica, Università Roma Tre, I-00146 Rome (Italy); Basso, V.; Kuepferling, M.; Coïsson, M.; Olivetti, E. S.; Celegato, F. [Istituto Nazionale di Ricerca Metrologica (INRIM), I-10135 Torino (Italy); Borgatti, F. [CNR, Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), I-40129 Bologna (Italy); Torelli, P.; Panaccione, G. [CNR, Istituto Officina dei Materiali (IOM), Lab. TASC, I-34149 Trieste (Italy); Tortora, L. [Laboratorio di Analisi di Superficie, Dipartimento di Matematica e Fisica, Università Roma Tre, I-00146 Rome (Italy); Dipartimento di Ingegneria Meccanica, Università Tor Vergata, I-00133 Rome (Italy); Stefani, G.; Offi, F. [Dipartimento di Scienze, Università Roma Tre, I-00146 Rome (Italy)

    2014-05-28

    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.

  20. Ground Liquefaction and Deformation Analysis of Breakwater Structures Under Earthquakes

    Directory of Open Access Journals (Sweden)

    Zhao Jie

    2016-10-01

    Full Text Available Ground liquefaction and deformation is one of the important causes that damage engineering structures. Chinese current code for seismic design of breakwater is based on the single-level seismic design method as well as code for port and water-way engineering. However, this code can not exactly reflect the seismic performance of breakwater structures which experience different seismic intensities. In this paper, the author used a finite difference software, namely, FLAC3D, to analyze the state and compute seismic responses of breakwater structure. The breakwater foundation’s pore pressure ratio and displacement due to different earthquake have been studied. And the result show that: Smaller earthquakes have little influence on serviceability of the foundation, and severe earthquakes can liquefy some parts of the foundation; In the latter case , obvious changes of pores and foundation displaces can be found. Particularly, when seismic peak acceleration reachs 0.2g, Liquefaction appears in the foundation and mainly concentrated in the upper right side of the structure. In addition, the survey of ultra-hole pressure and displacement values of sand layers of the breakwater, manifests when the ultra pore pressure near 1.0, displacement and overturning structure is relatively large, resulting in varying degrees of damage to the structure. This paper’s research can provide theoretical and designable reference for similar engineering structures

  1. Rapid Measurement of Tectonic Deformation Using Structure-from-Motion

    Science.gov (United States)

    Pickering, A.; DeLong, S.; Lienkaemper, J. J.; Hecker, S.; Prentice, C. S.; Schwartz, D. P.; Sickler, R. R.

    2016-12-01

    Rapid collection and distribution of accurate surface slip data after earthquakes can support emergency response, help coordinate scientific response, and constrain coseismic slip that can be rapidly overprinted by postseismic slip, or eliminated as evidence of surface deformation is repaired or obscured. Analysis of earthquake deformation can be achieved quickly, repeatedly and inexpensively with the use of Structure-from-Motion (SfM) photogrammetry. Traditional methods of measuring surface slip (e.g. manual measurement with tape measures) have proven inconsistent and irreproducible, and sophisticated methods such as laser scanning require specialized equipment and longer field time. Here we present a simple, cost-effective workflow for rapid, three-dimensional imaging and measurement of features affected by earthquake rupture. As part of a response drill performed by the USGS and collaborators on May 11, 2016, geologists documented offset cultural features along the creeping Hayward Fault in northern California, in simulation of a surface-rupturing earthquake. We present several photo collections from smart phones, tablets, and DSLR cameras from a number of locations along the fault collected by users with a range of experience. Using professionally calibrated photogrammetric scale bars we automatically and accurately scale our 3D models to 1 mm accuracy for precise measurement in three dimensions. We then generate scaled 3D point clouds and extract offsets from manual measurement and multiple linear regression for comparison with collected terrestrial scanner data. These results further establish dense photo collection and SfM processing as an important, low-cost, rapid means of quantifying surface deformation in the critical hours after a surface-rupturing earthquake and emphasize that researchers with minimal training can rapidly collect three-dimensional data that can be used to analyze and archive the surface effects of damaging earthquakes.

  2. Effect of Biaxial Isothermal Quasi-Continuous Deformation on Structure and Shape Memory Properties of Ti-Ni Alloys

    Science.gov (United States)

    Khmelevskaya, I.; Komarov, V.; Kawalla, R.; Prokoshkin, S.; Korpala, G.

    2017-08-01

    Severe plastic deformation (SPD) of Ti-50.0 at.% Ni alloy was carried out using the multi-axial deformation MaxStrain module of Gleeble system at 400, 370, 350 and 330 °C with accumulated true strains from e = 3.5 to 9.5. Kinetics of martensitic transformations was studied by DSC method, the structure features by x-ray diffraction and TEM. The recoverable strain was studied using a bending mode for strain inducing. A mixed nanocrystalline and nanosubgrained structure with average grain/subgrain size below 100 nm has been formed in a bulk sample as a result of SPD at as low as 330 °C. The resulting nanostructure provides an obvious advantage in the completely recoverable strain (9.3%) as compared to SPD at 350-400 °C (7-8%), and to reference treatment (2.5%). That correlates with Vickers hardness changes versus SPD strain.

  3. Superior tensile ductility in bulk metallic glass with gradient amorphous structure.

    Science.gov (United States)

    Wang, Q; Yang, Y; Jiang, H; Liu, C T; Ruan, H H; Lu, J

    2014-04-23

    Over centuries, structural glasses have been deemed as a strong yet inherently 'brittle' material due to their lack of tensile ductility. However, here we report bulk metallic glasses exhibiting both a high strength of ~2 GPa and an unprecedented tensile elongation of 2-4% at room temperature. Our experiments have demonstrated that intense structural evolution can be triggered in theses glasses by the carefully controlled surface mechanical attrition treatment, leading to the formation of gradient amorphous microstructures across the sample thickness. As a result, the engineered amorphous microstructures effectively promote multiple shear banding while delay cavitation in the bulk metallic glass, thus resulting in superior tensile ductility. The outcome of our research uncovers an unusual work-hardening mechanism in monolithic bulk metallic glasses and demonstrates a promising yet low-cost strategy suitable for producing large-sized, ultra-strong and stretchable structural glasses.

  4. Influence of superplastic deformation on the corrosion resistance of aluminum alloys with microcrystalline structure

    Energy Technology Data Exchange (ETDEWEB)

    Rabinovich, M.Kh.; Trifonov, V.G. [Inst. for Metals Superplasticity Problems, Ufa (Russian Federation)

    1997-12-31

    It was established that superplastic deformation of aluminum alloys with microcrystalline structure reduces their corrosion resistance. However, the use of superplastic deformation compared to hot deformation of coarsecrystalline alloys, permits to increase the resistance of aluminum alloys to intercrystalline corrosion and to stress-corrosion cracking. The analysis of the electrochemical nature of corrosion made it possible to establish the cause of the discovered effect of superplastic deformation on corrosion resistance. (orig.) 15 refs.

  5. STRUCTURAL AND MECHANICAL CHARACTERIZATION OF DEFORMED POLYMER USING CONFOCAL RAMAN MICROSCOPY AND DSC

    Directory of Open Access Journals (Sweden)

    Birgit Neitzel

    2016-02-01

    Full Text Available Polymers have various interesting properties, which depend largely on their inner structure. One way to influence the macroscopic behaviour is the deformation of the polymer chains, which effects the change in microstructure. For analyzing the microstructure of non-deformed and deformed polymer materials, Raman spectroscopy as well as differential scanning calorimetry (DSC were used. In the present study we compare the results for crystallinity measurements of deformed polymers using both methods in order to characterize the differences in micro-structure due to deformation. The study is ongoing, and we present the results of the first tests.

  6. Modeling level structures of odd-odd deformed nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Hoff, R.W.; Kern, J.; Piepenbring, R.; Boisson, J.P.

    1984-09-07

    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 /sup 238/Np, /sup 244/Am, and /sup 250/Bk 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.

  7. Determination of the refractive index of single crystal bulk samples and micro-structures

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt-Grund, R., E-mail: Schmidt-Grund@physik.uni-leipzig.de; Kuehne, P.; Czekalla, C.; Schumacher, D.; Sturm, C.; Grundmann, M.

    2011-02-28

    We present comparative studies for the exact determination of the refractive index of single crystals using spectroscopic ellipsometry and photonic-mode-structure investigations by means of spatially resolved photoluminescence spectroscopy, especially in the near band-gap spectral range. By applying such complementary methods we can overcome the uncertainties in the determination of the bulk refractive index introduced by surface properties. The physical effects used are the electromagnetic field reflection used by spectroscopic ellipsometry at large scale planar single crystals and the whispering-gallery-mode formation by total internal reflection in confined micro-structures. We demonstrate the applicability of such studies using the example of uniaxial ZnO bulk samples and micro-wires. By assuming a surface near region with electronic properties different from the bulk material, the method presented here gives the refractive index dispersion for both types of samples in an energy range from 1 to 3.4 eV.

  8. Periodic-Orbit Bifurcation and Shell Structure in Reflection-Asymmetric Deformed Cavity

    OpenAIRE

    Sugita, A.; Arita, K.; Matsuyanagi, K.

    1997-01-01

    Shell structure of the single-particle spectrum for reflection-asymmetric deformed cavity is investigated. Remarkable shell structure emerges for certain combinations of quadrupole and octupole deformations. Semiclassical periodic-orbit analysis indicates that bifurcation of equatorial orbits plays an important role in the formation of this new shell structure.

  9. 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.

  10. Structure of deformed wing virus, a major honey bee pathogen.

    Science.gov (United States)

    Škubník, Karel; Nováček, Jiří; Füzik, Tibor; Přidal, Antonín; Paxton, Robert J; Plevka, Pavel

    2017-03-21

    The worldwide population of western honey bees (Apis mellifera) is under pressure from habitat loss, environmental stress, and pathogens, particularly viruses that cause lethal epidemics. Deformed wing virus (DWV) from the family Iflaviridae, together with its vector, the mite Varroa destructor, is likely the major threat to the world's honey bees. However, lack of knowledge of the atomic structures of iflaviruses has hindered the development of effective treatments against them. Here, we present the virion structures of DWV determined to a resolution of 3.1 Å using cryo-electron microscopy and 3.8 Å by X-ray crystallography. The C-terminal extension of capsid protein VP3 folds into a globular protruding (P) domain, exposed on the virion surface. The P domain contains an Asp-His-Ser catalytic triad that is, together with five residues that are spatially close, conserved among iflaviruses. These residues may participate in receptor binding or provide the protease, lipase, or esterase activity required for entry of the virus into a host cell. Furthermore, nucleotides of the DWV RNA genome interact with VP3 subunits. The capsid protein residues involved in the RNA binding are conserved among honey bee iflaviruses, suggesting a putative role of the genome in stabilizing the virion or facilitating capsid assembly. Identifying the RNA-binding and putative catalytic sites within the DWV virion structure enables future analyses of how DWV and other iflaviruses infect insect cells and also opens up possibilities for the development of antiviral treatments.

  11. Asymmetric deformation structure of lava spine in Unzen Volcano, Japan

    Science.gov (United States)

    Miwa, T.; Okumura, S.; Matsushima, T.; Shimizu, H.

    2013-12-01

    variation of rock type is analogous to tectonic fault zone, suggesting that brittle failure of rigid magma due to contact with the conduit wall. Also similar variation is observed in the spine of Mt. St. Helens (Kendrick et al., 2012), which implies the existence of fault zone and brittle failure of magma are common features in the lava spine. The lava spine in Unzen volcano exhibits asymmetric deformation structure about direction of north and south. There is positive correlation between width and length in tectonic fault (Wells and Coppersmith, 1994). Therefore, development of fault zone (Sheared dacite, Tuffisite, and Breccia parts) in northern half may indicate that brittle failure starts at the deeper conduit for the northern half than the southern half of the spine. The asymmetry of magma ascent process is possible to result in asymmetries of outgassing path and location of volcanic earthquake in the conduit.

  12. Structural influence on atomic hopping and electronic states of Pd-based bulk metallic glasses

    OpenAIRE

    Tang, X.-P.; Löffler, Jörg F.; Schwarz, R. B.; Johnson, William L.; Wu, Yue

    2005-01-01

    Atomic motion and electronic structures of Pd–Ni–Cu–P bulk metallic glasses were investigated using 31P nuclear magnetic resonance. The hopping rate of P atoms was determined by the stimulated echo technique. Significant hopping was observed in all alloys well below the glass transition temperature. Increasing the Cu content to above 25 at. % increases P hopping significantly, consistent with the previous finding that the openness of the structure increases with Cu content. In contrast, P h...

  13. Bulk and interfacial structures of reline deep eutectic solvent: A molecular dynamics study

    Science.gov (United States)

    Kaur, Supreet; Sharma, Shobha; Kashyap, Hemant K.

    2017-11-01

    We apply all-atom molecular dynamics simulations to describe the bulk morphology and interfacial structure of reline, a deep eutectic solvent comprising choline chloride and urea in 1:2 molar ratio, near neutral and charged graphene electrodes. For the bulk phase structural investigation, we analyze the simulated real-space radial distribution functions, X-ray/neutron scattering structure functions, and their partial components. Our study shows that both hydrogen-bonding and long-range correlations between different constituents of reline play a crucial role to lay out the bulk structure of reline. Further, we examine the variation of number density profiles, orientational order parameters, and electrostatic potentials near the neutral and charged graphene electrodes with varying electrode charge density. The present study reveals the presence of profound structural layering of not only the ionic components of reline but also urea near the electrodes. In addition, depending on the electrode charge density, the choline ions and urea molecules render different orientations near the electrodes. The simulated number density and electrostatic potential profiles for reline clearly show the presence of multilayer structures up to a distance of 1.2 nm from the respective electrodes. The observation of positive values of the surface potential at zero charge indicates the presence of significant nonelectrostatic attraction between the choline cation and graphene electrode. The computed differential capacitance (Cd) for reline exhibits an asymmetric bell-shaped curve, signifying different variation of Cd with positive and negative surface potentials.

  14. On the modelling of the dynamics of elastically deformable floating structures

    DEFF Research Database (Denmark)

    Seng, Sopheak; Malenica, Sime; Jensen, Jørgen Juncher

    2015-01-01

    In this paper we are reexamining the dynamic equations of an elastically deformable floating structure to identify and evaluate the contribution from the inertia cross coupling terms which commonly have been neglected due to the assumption of small structural deformation. Numerical experiments on...

  15. A simulation model for analysing brain structure deformations

    Science.gov (United States)

    Di Bona, Sergio; Lutzemberger, Ludovico; Salvetti, Ovidio

    2003-12-01

    Recent developments of medical software applications—from the simulation to the planning of surgical operations—have revealed the need for modelling human tissues and organs, not only from a geometric point of view but also from a physical one, i.e. soft tissues, rigid body, viscoelasticity, etc. This has given rise to the term 'deformable objects', which refers to objects with a morphology, a physical and a mechanical behaviour of their own and that reflects their natural properties. In this paper, we propose a model, based upon physical laws, suitable for the realistic manipulation of geometric reconstructions of volumetric data taken from MR and CT scans. In particular, a physically based model of the brain is presented that is able to simulate the evolution of different nature pathological intra-cranial phenomena such as haemorrhages, neoplasm, haematoma, etc and to describe the consequences that are caused by their volume expansions and the influences they have on the anatomical and neuro-functional structures of the brain.

  16. A simulation model for analysing brain structure deformations

    Energy Technology Data Exchange (ETDEWEB)

    Bona, Sergio Di [Institute for Information Science and Technologies, Italian National Research Council (ISTI-8211-CNR), Via G Moruzzi, 1-56124 Pisa (Italy); Lutzemberger, Ludovico [Department of Neuroscience, Institute of Neurosurgery, University of Pisa, Via Roma, 67-56100 Pisa (Italy); Salvetti, Ovidio [Institute for Information Science and Technologies, Italian National Research Council (ISTI-8211-CNR), Via G Moruzzi, 1-56124 Pisa (Italy)

    2003-12-21

    Recent developments of medical software applications from the simulation to the planning of surgical operations have revealed the need for modelling human tissues and organs, not only from a geometric point of view but also from a physical one, i.e. soft tissues, rigid body, viscoelasticity, etc. This has given rise to the term 'deformable objects', which refers to objects with a morphology, a physical and a mechanical behaviour of their own and that reflects their natural properties. In this paper, we propose a model, based upon physical laws, suitable for the realistic manipulation of geometric reconstructions of volumetric data taken from MR and CT scans. In particular, a physically based model of the brain is presented that is able to simulate the evolution of different nature pathological intra-cranial phenomena such as haemorrhages, neoplasm, haematoma, etc and to describe the consequences that are caused by their volume expansions and the influences they have on the anatomical and neuro-functional structures of the brain.

  17. 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.; hide

    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

  18. Surface and bulk electronic structure of thin-film wurtzite GaN

    Energy Technology Data Exchange (ETDEWEB)

    Dhesi, S.S.; Stagarescu, C.B.; Smith, K.E. [Department of Physics, Boston University, Boston, Massachusetts 02215 (United States); Doppalapudi, D.; Singh, R.; Moustakas, T.D. [Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts 02215 (United States)

    1997-10-01

    The bulk and surface valence-band electronic structure of thin-wurtzite GaN has been studied using angle-resolved photoemission spectroscopy. The bulk band dispersion along the {Gamma}{Delta}A, {Gamma}{Sigma}M, and {Gamma}TK directions of the bulk Brillouin zone was measured. Our results indicate the local-density approximation band-structure calculations using partial-core corrections for the Ga 3d states predict the relative dispersion of many of the observed bands with a high degree of accuracy. Furthermore, a nondispersive feature was identified near the valence-band maximum in a region of k space devoid of bulk states. This feature is identified as emission from a surface state on GaN(0001)-(1{times}1). The symmetry of this surface state is even with respect to the mirror planes of the surface and polarization measurements indicate that it is of sp{sub z} character, consistent with a dangling-bond state. {copyright} {ital 1997} {ital The American Physical Society}

  19. Complex structure-induced deformations of σ-models

    Energy Technology Data Exchange (ETDEWEB)

    Bykov, Dmitri [Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut,Am Mühlenberg 1, D-14476 Potsdam-Golm (Germany); Steklov Mathematical Institute of Russ. Acad. Sci.,Gubkina str. 8, 119991 Moscow (Russian Federation)

    2017-03-24

    We describe a deformation of the principal chiral model (with an even-dimensional target space G) by a B-field proportional to the Kähler form on the target space. The equations of motion of the deformed model admit a zero-curvature representation. As a simplest example, we consider the case of G=S{sup 1}×S{sup 3}. We also apply a variant of the construction to a deformation of the AdS{sub 3}×S{sup 3}×S{sup 1} (super-)σ-model.

  20. Plastic Deformation of Metal Surfaces

    DEFF Research Database (Denmark)

    Hansen, Niels; Zhang, Xiaodan; Huang, Xiaoxu

    2013-01-01

    parameters by TEM and EBSD and apply strength-structural relationships established for the bulk metal deformed to high strains. This technique has been applied to steel deformed by high energy shot peening and a calculated stress gradient at or near the surface has been successfully validated by hardness......Plastic deformation of metal surfaces by sliding and abrasion between moving parts can be detrimental. However, when the plastic deformation is controlled for example by applying different peening techniques hard surfaces can be produced which can increase the fracture resistance and fatigue life...

  1. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, C. [School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072 (China); Laboratoire de Mecanique des Contacts et des Structures (LaMCoS), INSA Lyon, 20 Avenue des Sciences, F-69621 Villeurbanne Cedex (France); Li, H. [School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072 (China); Li, M.Q., E-mail: zc9997242256@126.com [School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072 (China)

    2016-05-15

    Graphical abstract: This study focused on the detailed analysis of surface asperity deformation mechanism in diffusion bonding of steel hollow structural component. A special surface with regular patterns was processed to be joined so as to observe the extent of surface asperity deformation under different applied bonding pressures. 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. - Highlights: • A high quality hollow structural component has been fabricated by diffusion bonding. • Surface asperity deformation not only expands the interfacial contact areas, but also causes deformation heat and defects to improve the atomic diffusion. • Surface asperity deformation introduces the stored energy difference between the two opposite sides of interface grain boundary, leading to strain induced interface grain boundary migration. • The void exerts a dragging force on the interface grain boundary to retard or stop interface grain boundary migration. - Abstract: 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

  3. Microwave Structural Health Monitoring Sensor for Deformation Measurement of Bended Steel Structures: Influence of Curvature Effect

    Directory of Open Access Journals (Sweden)

    P. Lopato

    2017-12-01

    Full Text Available In this paper the utilization of microstrip antenna sensor for deformation monitoring in bended steel structures is presented. This kind of sensing element can be used in structural health monitoring systems. Deformation measurement by patch sensor is based on the reflection coefficient S11 investigation. So far, relationship between resonant frequency and change of patch dimensions was considered in literature only for planar microstrip sensors. In case of samples subjected to bending process the sensor geometry became non-planar. This fact affects measured resonant frequency, thus it should be studied. In order to analyse influence of patch sensor curvature on resonant frequency during bending process Finite Element Method (FEM simulations were carried out. Results of analysis were experimentally verified.

  4. On the adsorption properties of magnetic fluids: Impact of bulk structure

    Energy Technology Data Exchange (ETDEWEB)

    Kubovcikova, Martina [Institute of Experimental Physics, Slovak Academy of Sciences, Kosice (Slovakia); Gapon, Igor V. [Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna (Russian Federation); Physics Department, Kyiv Taras Shevchenko National University, Kyiv (Ukraine); Zavisova, Vlasta [Institute of Experimental Physics, Slovak Academy of Sciences, Kosice (Slovakia); Koneracka, Martina, E-mail: konerack@saske.sk [Institute of Experimental Physics, Slovak Academy of Sciences, Kosice (Slovakia); Petrenko, Viktor I. [Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna (Russian Federation); Physics Department, Kyiv Taras Shevchenko National University, Kyiv (Ukraine); Soltwedel, Olaf [Max-Planck-Institut for Solid State Research, Outstation at MLZ, Garching (Germany); Almasy, László [Wigner Research Centre for Physics, Hungarian Academy of Sciences, Budapest (Hungary); Avdeev, Mikhail V. [Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna (Russian Federation); Physical Faculty, St. Petersburg State University, Saint Petersburg (Russian Federation); Kopcansky, Peter [Institute of Experimental Physics, Slovak Academy of Sciences, Kosice (Slovakia)

    2017-04-01

    Adsorption of nanoparticles from magnetic fluids (MFs) on solid surface (crystalline silicon) was studied by neutron reflectometry (NR) and related to the bulk structural organization of MFs concluded from small-angle neutron scattering (SANS). The initial aqueous MF with nanomagnetite (co-precipitation reaction) stabilized by sodium oleate and MF modified by a biocompatible polymer, poly(ethylene glycol) (PEG), were considered. Regarding the bulk structure it was confirmed in the SANS experiment that comparatively small and compact (size~30 nm) aggregates of nanoparticle in the initial sample transfer to large and developed (size>130 nm, fractal dimension 2.7) associates in the PEG modified MF. This reorganization in the aggregates correlates with the changes in the neutron reflectivity that showed that a single adsorption layer of individual nanoparticles on the oxidized silicon surface for the initial MF disappears after the PEG modification. It is concluded that all particles in the modified fluid are in the aggregates that are not adsorbed by silicon. - Highlights: • Different bulk structure of initial MF and PEG modified MF was confirmed. • PEG modification of MF transforms small MNPs aggregates to large and developed. • Individual non-aggregated nanoparticles are preferably adsorbed on oxidized silicon. • Nanoparticles from MF form a single adsorption layer on the silicon surface. • PEG modified MF compose large developed aggregates that are not adsorbed by surface.

  5. Structure, Properties, and Crystallization of Mg-Cu-Y-Zn Bulk Metallic Glasses

    Science.gov (United States)

    Babilas, Rafał; Cesarz-Andraczke, Katarzyna; Nowosielski, Ryszard; Burian, Andrzej

    2014-06-01

    The Mg60Cu30Y10 and Mg65Cu20Y10Zn5 bulk metallic glasses in the form of a rod 2 mm in diameter were successfully prepared by the conventional Cu-mold casting method. The addition of Zn caused the decrease in the crystallization and melting temperatures in comparison with the Mg60Cu30Y10 alloy. The crystallization and melting temperatures are crucial factors that influence the casting process. An increase in annealing temperature leads to structural changes by the formation of the crystalline phases and lowers the compressive strength. These results obtained for the Mg-based bulk metallic glasses (Mg-BMGs) are important for some practical reasons, in particular, for developing the fabrication process. It has been shown that minor addition of an alloying element can change glass-forming ability and strength of the Mg-BMGs.

  6. Anisotropic Poly(Vinyl Alcohol) Hydrogel: Connection Between Structure and Bulk Mechanical Properties

    Science.gov (United States)

    Hudson, Stephen; Hutter, Jeffrey; Millon, Leonardo; Wan, Wankei; Nieh, Mu-Ping

    2009-03-01

    Poly(vinyl alcohol) (PVA) hydrogels are formed from PVA solution by creation of physical cross-links during freeze/thaw cycling. By choosing a suitable freeze/thaw protocol and applying a strain during thermal processing, gels with permanent, anisotropic bulk mechanical properties matching those of cardiovascular tissues can be made, making them useful for applications ranging from artificial heart valves to vascular grafts. We have performed small- and ultra small-angle neutron scattering (SANS and USANS) measurements covering length scales from 2 nm to 10 μm, and modeled the structure as interconnected PVA blobs of size 20 to 50 nm arranged in fractal aggregates extending to at least 10 μm. Here, we discuss the relationship between the microstructure and bulk mechanical properties. Strength increases with the number of thermal cycles due to reinforcement of the small-scale gel phase, while anisotropy is due to elongation of the much larger fractal aggregates.

  7. Determination of Velocity And Acceleration of Structural Deformation ...

    African Journals Online (AJOL)

    This paper outlines the procedure of geodetic monitoring system of circular oil storage tanks and presents the analysis of the resulted observations to determine the values of their deformation. At the Forcados Tank Farm, there are eighteen tanks currently used for crude oil storage. In this study, only tank 6 was used as case ...

  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. Crystal structures of model lithium halides in bulk phase and in clusters

    Science.gov (United States)

    Lanaro, G.; Patey, G. N.

    2017-04-01

    We employ lattice energy calculations and molecular dynamics simulations to compare the stability of wurtzite and rock salt crystal structures of four lithium halides (LiF, LiCl, LiBr, and LiI) modeled using the Tosi-Fumi and Joung-Cheatham potentials, which are models frequently used in simulation studies. Both infinite crystals and finite clusters are considered. For the Tosi-Fumi model, we find that all four salts prefer the wurtzite structure both at 0 K and at finite temperatures, in disagreement with experiments, where rock salt is the stable structure and wurtzite exists as a metastable state. For Joung-Cheatham potentials, rock salt is more stable for LiF and LiCl, but the wurtzite structure is preferred by LiBr and LiI. It is clear that the available lithium halide force fields need improvement to bring them into better accord with the experiment. Finite-size clusters that are more stable as rock salt in the bulk phase tend to solidify as small rock salt crystals. However, small clusters of salts that prefer the wurtzite structure as bulk crystals tend to form structures that have hexagonal motifs, but are not finite-size wurtzite crystals. We show that small wurtzite structures are unstable due to the presence of a dipole and rearrange into more stable, size-dependent structures. We also show that entropic contributions can act in favor of the wurtzite structure at higher temperatures. The possible relevance of our results for simulation studies of crystal nucleation from melts and/or aqueous solutions is discussed.

  10. Fluid-structure interaction simulations of deformable structures with non-linear thin shell elements

    Science.gov (United States)

    Asgharzadeh, Hafez; Hedayat, Mohammadali; Borazjani, Iman; Scientific Computing; Biofluids Laboratory Team

    2017-11-01

    Large deformation of structures in a fluid is simulated using a strongly coupled partitioned fluid-structure interaction (FSI) approach which is stabilized with under-relaxation and the Aitken acceleration technique. The fluid is simulated using a recently developed implicit Newton-Krylov method with a novel analytical Jacobian. Structures are simulated using a triangular thin-shell finite element formulation, which considers only translational degrees of freedom. The thin-shell method is developed on the top of a previously implemented membrane finite element formulation. A sharp interface immersed boundary method is used to handle structures in the fluid domain. The developed FSI framework is validated against two three-dimensional experiments: (1) a flexible aquatic vegetation in the fluid and (2) a heaving flexible panel in fluid. Furthermore, the developed FSI framework is used to simulate tissue heart valves, which involve large deformations and non-linear material properties. This work was supported by American Heart Association (AHA) Grant 13SDG17220022 and the Center of Computational Research (CCR) of University at Buffalo.

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

    Directory of Open Access Journals (Sweden)

    Ehsan Hatefi

    2016-09-01

    Full Text Available 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+14 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.

  12. The structure of ammonia molecules on MgO(100) surfaces from monolayer to bulk condensation

    Science.gov (United States)

    Panella, V.; Suzanne, J.; Coulomb, J.-P.

    1996-04-01

    The structure of ND 3 molecules adsorbed on MgO (100) surfaces has been studied by neutron diffraction within the 10-80 K temperature range and at 0.7, 1 and 2.3 monolayer coverage. The neutron spectra suggest that the monolayer presents a short range order with a hcp packing of ammonia molecules, a coherence length of 25 ± 2 Å and a nearest neighbour distance of 3.61 ± 0.04 Å The molecular spacing remains the same between 10 and 80K that we interpret as small higher order commensurate islands. Above one monolayer coverage, bulk crystallites form on top of the first monolayer.

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

    Directory of Open Access Journals (Sweden)

    Annarosa Gugliuzza

    2016-05-01

    Full Text Available 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.

  14. Research on deformations which appear in within the metal structures of mining equipment

    Directory of Open Access Journals (Sweden)

    G. Paraschiv

    2014-10-01

    Full Text Available Metal structures of the mining equipment are made of a steel with good weldability and mechanical characteristics corresponding and namely St 52.3 steel that allows the use of these metal structures in heavy duty. Metal structures of the mining equipment are very large structures and strong requested mechanical, and in these conditions during exploitation can occur large deformations at these that may cause a decrease in the exploitation safety of mining equipment. Research has followed in principal the analyze of deformations appear in metallic structures, and for realizing the researches has been used both a dimensional analysis and one that is based on the finite element method.

  15. Deformations of topological open strings

    NARCIS (Netherlands)

    Hofman, C.; Ma, Whee Ky

    Deformations of topological open string theories are described, with an emphasis on their algebraic structure. They are encoded in the mixed bulk-boundary correlators. They constitute the Hochschild complex of the open string algebra - the complex of multilinear maps on the boundary Hilbert space.

  16. On the adsorption properties of magnetic fluids: Impact of bulk structure

    Science.gov (United States)

    Kubovcikova, Martina; Gapon, Igor V.; Zavisova, Vlasta; Koneracka, Martina; Petrenko, Viktor I.; Soltwedel, Olaf; Almasy, László; Avdeev, Mikhail V.; Kopcansky, Peter

    2017-04-01

    Adsorption of nanoparticles from magnetic fluids (MFs) on solid surface (crystalline silicon) was studied by neutron reflectometry (NR) and related to the bulk structural organization of MFs concluded from small-angle neutron scattering (SANS). The initial aqueous MF with nanomagnetite (co-precipitation reaction) stabilized by sodium oleate and MF modified by a biocompatible polymer, poly(ethylene glycol) (PEG), were considered. Regarding the bulk structure it was confirmed in the SANS experiment that comparatively small and compact (size 30 nm) aggregates of nanoparticle in the initial sample transfer to large and developed (size>130 nm, fractal dimension 2.7) associates in the PEG modified MF. This reorganization in the aggregates correlates with the changes in the neutron reflectivity that showed that a single adsorption layer of individual nanoparticles on the oxidized silicon surface for the initial MF disappears after the PEG modification. It is concluded that all particles in the modified fluid are in the aggregates that are not adsorbed by silicon.

  17. A GaN bulk crystal with improved structural quality grown by the ammonothermal method.

    Science.gov (United States)

    Hashimoto, Tadao; Wu, Feng; Speck, James S; Nakamura, Shuji

    2007-08-01

    The realization of high-performance optoelectronic devices, based on GaN and other nitride semiconductors, requires the existence of a high-quality substrate. Non-polar or semipolar substrates have recently been proven to provide superior optical devices to those on conventional c-plane substrates. Bulk GaN growth enables GaN substrates sliced along various favourable crystal orientations. Ammonothermal growth is an attractive method for bulk GaN growth owing to its potential to grow GaN ingots at low cost. Here we report on improvement in the structural quality of GaN grown by the ammonothermal method. The threading dislocation densities estimated by plan-view transmission electron microscopy observations were less than 1 x 10(6) cm(-2) for the Ga face and 1 x 10(7) cm(-2) for the N face. No dislocation generation at the interface was observed on the Ga face, although a few defects were generated at the interface on the N face. The improvement in the structural quality, together with the previous report on growth rate and scalability, demonstrates the commercial feasibility of the ammonothermal GaN growth.

  18. Shear Creep Simulation of Structural Plane of Rock Mass Based on Discontinuous Deformation Analysis

    Directory of Open Access Journals (Sweden)

    Guoxin Zhang

    2017-01-01

    Full Text Available Numerical simulations of the creep characteristics of the structural plane of rock mass are very useful. However, most existing simulation methods are based on continuum mechanics and hence are unsuitable in the case of large displacements and deformations. The discontinuous deformation analysis method proposed by Genhua is a discrete one and has a significant advantage when simulating the contacting problem of blocks. In this study, we combined the viscoelastic rheological model of Burgers with the discontinuous deformation analysis (DDA method. We also derived the recurrence formula for the creep deformation increment with the time step during numerical simulations. Based on the minimum potential energy principle, the general equilibrium equation was derived, and the shear creep deformation in the structural plane was considered. A numerical program was also developed and its effectiveness was confirmed based on the curves obtained by the creep test of the structural plane of a rock mass under different stress levels. Finally, the program was used to analyze the mechanism responsible for the creep features of the structural plane in the case of the toppling deformation of the rock slope. The results showed that the extended DDA method is an effective one.

  19. Fluid-structure interaction analysis of deformation of sail of 30-foot yacht

    Directory of Open Access Journals (Sweden)

    Sera Bak

    2013-06-01

    Full Text Available Most yacht sails are made of thin fabric, and they have a cambered shape to generate lift force; however, their shape can be easily deformed by wind pressure. Deformation of the sail shape changes the flow characteristics over the sail, which in turn further deforms the sail shape. Therefore, fluid-structure interaction (FSI analysis is applied for the precise evaluation or optimization of the sail design. In this study, fluid flow analyses are performed for the main sail of a 30-foot yacht, and the results are applied to loading conditions for structural analyses. By applying the supporting forces from the rig, such as the mast and boom-end outhaul, as boundary conditions for structural analysis, the deformed sail shape is identified. Both the flow analyses and the structural analyses are iteratively carried out for the deformed sail shape. A comparison of the flow characteristics and surface pressures over the deformed sail shape with those over the initial shape shows that a considerable difference exists between the two and that FSI analysis is suitable for application to sail design.

  20. Mechanical design of deformation compensated flexural pivots structured for linear nanopositioning stages

    Science.gov (United States)

    Shu, Deming; Kearney, Steven P.; Preissner, Curt A.

    2015-02-17

    A method and deformation compensated flexural pivots structured for precision linear nanopositioning stages are provided. A deformation-compensated flexural linear guiding mechanism includes a basic parallel mechanism including a U-shaped member and a pair of parallel bars linked to respective pairs of I-link bars and each of the I-bars coupled by a respective pair of flexural pivots. The basic parallel mechanism includes substantially evenly distributed flexural pivots minimizing center shift dynamic errors.

  1. Evaluation of structural deformations of a mechanical connecting unit oxidizer supplies by thermo-mechanical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sang Woo [Dept. of Mechanical Engineering, Institute of Machine Convergence Technology, Hankyong National University, Anseong (Korea, Republic of)

    2016-10-15

    A Mechanical connecting unit (MCU) used in ground facilities for a Liquid propellant rocket (LPR) acts as a bridge between the onboard system and the ground oxidizer filling system. It should be resistant to structural deformations in order to guarantee successful supply of a cryogenic oxidizer and high pressure gases without reduction of sealing capability. The MCU consists of many components and linkages and operates under harsh conditions induced by a cryogenic oxidizer, high pressure gases and other mechanical forces. Thus, the evaluation of structural deformation of the MCU considering complex conditions is expensive and time consuming. The present study efficiently evaluates the structural deformations of the key components of the MCU by Thermo-mechanical simulation (TMS) based on the superposition principle. Deformations due to the mechanical loadings including weights, pressures, and spring forces are firstly evaluated by using a non-linear flexible body simulation module (FFlex) of Multi-body dynamics (MBD) software, RecurDyn. Then, thermal deformations for the deformed geometries obtained by RecurDyn were subsequently calculated. It was conducted by using a Finite element (FE) analysis software, ANSYS. The total deformations for the onboard plate and multi-channel plate in the connecting section due to the mechanical and thermal loadings were successfully evaluated. Moreover, the outer gaps at six points between two plates were calculated and verified by comparison to the measured data. Their values and tendencies showed a good agreement. The author concluded that the TMS using MBD software considering flexible bodies and an FE simulator can efficiently evaluate structural deformations of the MCU operating under the complex load and boundary conditions.

  2. The mechanical properties of austenite stainless steel 304 after structural deformation through cold work

    Energy Technology Data Exchange (ETDEWEB)

    Mubarok, Naila; Manaf, Azwar, E-mail: azwar@ui.ac.id [PPS Materials Science, FMIPA-Universitas Indonesia, Depok 16424 (Indonesia); Notonegoro, Hamdan Akbar [Mechanical Engineering Dept., FT-Universitas Sultan Ageng Tirtayasa,Cilegon 42435 (Indonesia); Thosin, Kemas Ahmad Zaini [Pusat Penelitian Fisika,LIPI, Serpong (Indonesia)

    2016-06-17

    The 304 stainless steel (SS) type is widely used in oil and gas operations due to its excellent corrosion resistance. However, the presence of the fine sand particles and H{sub 2}S gas contained in crude oil could lead the erosion and abrasion in steel. In this study, cold rolled treatments were conducted to the 304 SS in order to increase the wear resistance of the steel. The cold work has resulted in thickness reduction to 20%, 40% and 60% of the original. Various microstructural characterizations were used to analyze the effect of deformation. The hardness characterization showed that the initial hardness value increased from 145 HVC to 395 HVC as the level of deformation increase. Further, the wear resistance increased with the deformation rate from 0% to 40% and subsequently decreased from 40% to 60% deformation rate. Microstructural characterization shows that the boundary change to coincide by 56 µm, 49 µm, 45 µm, and 43 µm width and the grain go to flatten and being folded like needles. The effect of deformation on the grain morphology and structure was also studied by optical metallography and X-Ray Diffraction. It is shown that the deformation by means of a cold rolled process has transformed the austenite structure into martensitic structure.

  3. Structure and properties of deformable nickel alloys for gas turbines

    Science.gov (United States)

    Filatova, M. A.; Sudakov, V. S.

    1994-12-01

    The construction of high power gas turbine installations necessitates the development and use of new high-strength heat-resistant nickel alloys for large forged turbine blades. The blade material must possess not only superior properties (high temperature strength, ductility, fatigue and thermal fatigue strength, stability in the fuel combustion products) but also the required level of metallurgical and manufacturing producibility. The results of a study of the deformable nickel alloys KhN65KVMYuTB (ÉK78), KhN65KMVYuB (ÉP800), and KhN60KVYuMB (ÉP957), which have substantially better properties than the alloy now used for gas turbine blades (KhN65VMTYu) (ÉI893), are presented in this article.

  4. 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.

  5. Influence of Plastic Deformation on Martensitic Transformation During Hot Stamping of Complex Structure Auto Parts

    Science.gov (United States)

    Shen, Yuhan; Song, Yanli; Hua, Lin; Lu, Jue

    2017-04-01

    The ultra-high strength steel auto parts manufactured by hot stamping are widely applied for weight reduction and safety improvement. During the hot stamping process, hot forming and quenching are performed in one step wherein plastic deformation and phase transformation simultaneously take place and affect each other. Thereinto, the influence of deformation on martensitic transformation is of great importance. In the present paper, the influence of plastic deformation on martensitic transformation during hot stamping of complex structure auto parts was investigated. For this purpose, a B-pillar reinforced panel in B1500HS steel was manufactured by hot stamping, and the process was simulated by finite element software based on a thermo-mechanical-metallurgical coupled model. Considering various deformation degrees, the microstructures and mechanical properties at four typical locations of the hot stamped B-pillar reinforced panel were detected. The results show that the martensitic content and the microhardness increase with the increase in the deformation amount. There are two reasons causing this phenomenon: (1) the increase in mechanical driving force and (2) the increased probability of the martensitic nucleation at crystal defects. The x-ray diffraction analysis indicates the carbon enrichment in retained austenite which results from the carbon diffusion during the low-carbon martensite formation. Furthermore, the carbon content decreases with the increase in the deformation amount, because the deformation of austenite suppresses the carbon diffusion.

  6. 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

  7. Soft-sediment deformation structures in NW Germany caused by Late Pleistocene seismicity

    Science.gov (United States)

    Brandes, Christian; Winsemann, Jutta

    2013-11-01

    New data on seismically triggered soft-sediment deformation structures in Pleniglacial to Late Glacial alluvial fan and aeolian sand-sheet deposits of the upper Senne area link this soft-sediment deformation directly to earthquakes generated along the Osning Thrust, which is one of the major fault systems in Central Europe. Soft-sediment deformation structures include a complex fault and fold pattern, clastic dikes, sand volcanoes, sills, irregular intrusive sedimentary bodies, flame structures, and ball-and-pillow structures. The style of soft-sediment deformation will be discussed with respect to brittle failure, liquefaction and fluidization processes, and was controlled by (1) the magnitude of the earthquake and (2) the permeability, tensile strength and flexural resistance of the alluvial and aeolian sediments. It is the first time in northern Germany that fluidization and liquefaction features can be directly related to a fault. The occurrence of seismicity in the Late Pleistocene and in the seventeenth century indicates ongoing crustal movements along the Osning Thrust and sheds new light on the seismic activity of northern Germany. The Late Pleistocene earthquake probably occurred between 15.9 ± 1.6 and 13.1 ± 1.5 ka; the association of soft-sediment deformation structures implies that it had a magnitude of at least 5.5.

  8. 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.

  9. Dynamical effects and terahertz harmonic generation in low-doped bulk semiconductors and submicron structures

    Energy Technology Data Exchange (ETDEWEB)

    Persano Adorno, D.; Capizzo, M.C.; Zarcone, M. [Dipartimento di Fisica e Tecnologie Relative, Viale delle Scienze, Ed. 18, 90128, Palermo (Italy)

    2006-08-15

    We present results obtained using a three-dimensional multivalleys Monte Carlo (MC) model to simulate the nonlinear carrier dynamics under the influence of an intense sub-terahertz electric field in a doped bulk semiconductor. By self-consistently coupling a one-dimensional Poisson solver to the ensemble MC code we simulate also the nonlinear carrier dynamics in n{sup +}nn{sup +} structures operating under large-amplitude periodic signals and investigate the voltage-current characteristic hysteresis cycle and the high-order harmonic efficiency. For both cases we discuss the dependence of the nonlinearities and of the harmonic generation efficiency on the frequency and the intensity of the alternating signal. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Comparative Visual Analysis of Structure-Performance Relations in Complex Bulk-Heterojunction Morphologies

    KAUST Repository

    Aboulhassan, A.

    2017-07-04

    The structure of Bulk-Heterojunction (BHJ) materials, the main component of organic photovoltaic solar cells, is very complex, and the relationship between structure and performance is still largely an open question. Overall, there is a wide spectrum of fabrication configurations resulting in different BHJ morphologies and correspondingly different performances. Current state-of-the-art methods for assessing the performance of BHJ morphologies are either based on global quantification of morphological features or simply on visual inspection of the morphology based on experimental imaging. This makes finding optimal BHJ structures very challenging. Moreover, finding the optimal fabrication parameters to get an optimal structure is still an open question. In this paper, we propose a visual analysis framework to help answer these questions through comparative visualization and parameter space exploration for local morphology features. With our approach, we enable scientists to explore multivariate correlations between local features and performance indicators of BHJ morphologies. Our framework is built on shape-based clustering of local cubical regions of the morphology that we call patches. This enables correlating the features of clusters with intuition-based performance indicators computed from geometrical and topological features of charge paths.

  11. 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.

  12. High energy photoelectron spectroscopy in basic and applied science: Bulk and interface electronic structure

    Energy Technology Data Exchange (ETDEWEB)

    Knut, Ronny; Lindblad, Rebecka [Department of Physics and Astronomy, Uppsala University, SE-751 21 Uppsala (Sweden); Gorgoi, Mihaela [Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin (Germany); Rensmo, Håkan [Department of Physics and Astronomy, Uppsala University, SE-751 21 Uppsala (Sweden); Karis, Olof, E-mail: olof.karis@physics.uu.se [Department of Physics and Astronomy, Uppsala University, SE-751 21 Uppsala (Sweden)

    2013-10-15

    Highlights: •We demonstrate how hard X-ray photoelectron spectroscopy can be used to investigate interface properties of multilayers. •By combining HAXPES and statistical methods we are able to provide quantitative analysis of the interface diffusion process. •We show how photoionization cross sections can be used to map partial density of states contributions to valence states. •We use HAXPES to provide insight into the valence electronic structure of e.g. multiferroics and dye-sensitized solar cells. -- Abstract: With the access of new high-performance electron spectrometers capable of analyzing electron energies up to the order of 10 keV, the interest for photoelectron spectroscopy has grown and many new applications of the technique in areas where electron spectroscopies were considered to have limited use have been demonstrated over the last few decades. The technique, often denoted hard X-ray photoelectron spectroscopy (HX-PES or HAXPES), to distinguish the experiment from X-ray photoelectron spectroscopy performed at lower energies, has resulted in an increasing interest in photoelectron spectroscopy in many areas. The much increased mean free path at higher kinetic energies, in combination with the elemental selectivity of the core level spectroscopies in general has led to this fact. It is thus now possible to investigate the electronic structure of materials with a substantially enhanced bulk sensitivity. In this review we provide examples from our own research using HAXPES which to date has been performed mainly at the HIKE facility at the KMC-1 beamline at HZB, Berlin. The review exemplifies the new opportunities using HAXPES to address both bulk and interface electronic properties in systems relevant for applications in magnetic storage, energy related research, but also in purely curiosity driven problems.

  13. Bridge Structure Deformation Prediction Based on GNSS Data Using Kalman-ARIMA-GARCH Model.

    Science.gov (United States)

    Xin, Jingzhou; Zhou, Jianting; Yang, Simon X; Li, Xiaoqing; Wang, Yu

    2018-01-19

    Bridges are an essential part of the ground transportation system. Health monitoring is fundamentally important for the safety and service life of bridges. A large amount of structural information is obtained from various sensors using sensing technology, and the data processing has become a challenging issue. To improve the prediction accuracy of bridge structure deformation based on data mining and to accurately evaluate the time-varying characteristics of bridge structure performance evolution, this paper proposes a new method for bridge structure deformation prediction, which integrates the Kalman filter, autoregressive integrated moving average model (ARIMA), and generalized autoregressive conditional heteroskedasticity (GARCH). Firstly, the raw deformation data is directly pre-processed using the Kalman filter to reduce the noise. After that, the linear recursive ARIMA model is established to analyze and predict the structure deformation. Finally, the nonlinear recursive GARCH model is introduced to further improve the accuracy of the prediction. Simulation results based on measured sensor data from the Global Navigation Satellite System (GNSS) deformation monitoring system demonstrated that: (1) the Kalman filter is capable of denoising the bridge deformation monitoring data; (2) the prediction accuracy of the proposed Kalman-ARIMA-GARCH model is satisfactory, where the mean absolute error increases only from 3.402 mm to 5.847 mm with the increment of the prediction step; and (3) in comparision to the Kalman-ARIMA model, the Kalman-ARIMA-GARCH model results in superior prediction accuracy as it includes partial nonlinear characteristics (heteroscedasticity); the mean absolute error of five-step prediction using the proposed model is improved by 10.12%. This paper provides a new way for structural behavior prediction based on data processing, which can lay a foundation for the early warning of bridge health monitoring system based on sensor data using sensing

  14. 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.

  15. Topography and structural heterogeneities in surface ground deformation: a simulation test for Somma-Vesuvius volcano

    Science.gov (United States)

    Tammaro, Umberto; Riccardi, Umberto; Romano, Vittorio; Meo, Michele; Capuano, Paolo

    2017-04-01

    Through a 3D finite element code we simulate, the deformation of Somma-Vesuvius volcano caused by some overpressure sources. Under the assumption of linear elastic isotropic material behavior, the volcano deformation sources are located at various depths and their geometry (shape and lateral extension) is mainly constrained by the results of recent seismic tomography studies. These simulations have the objective to inquire about the influence of topography and structural heterogeneity on ground deformation. Structural heterogeneities have been modeled in terms of dynamical elastic parameters (Young's modulus) accounting for previous seismic tomography and gravity studies. Topography of Somma-Vesuvius is taken into account, using a digital terrain model. The main outcomes of this study is a strong deviation from axially symmetric pattern of the displacement field, which is quietly unaccounted by simplistic Mogi modeling in homogeneous medium with simplified topography. These results demonstrate that real topography and structural heterogeneities are key factors controlling the pattern of ground deformations, i.e. one of the most relevant problem in volcano monitoring. Moreover, an improved knowledge of deformation patterns can significantly help in the location of monitoring sensors as well as in the design of an efficient geodetic network.

  16. Measurement of deforming mode of lattice truss structures under impact loading

    Directory of Open Access Journals (Sweden)

    Zhao H.

    2012-08-01

    Full Text Available Lattice truss structures, which are used as a core material in sandwich panels, were widely investigated experimentally and theoretically. However, explanation of the deforming mechanism using reliable experimental results is almost rarely reported, particularly for the dynamic deforming mechanism. The present work aimed at the measurement of the deforming mode of lattice truss structures. Indeed, quasi-static and Split Hopkinson Pressure Bar (SHPB tests have been performed on the tetrahedral truss cores structures made of Aluminum 3003-O. Global values such as crushing forces and displacements between the loading platens are obtained. However, in order to understand the deforming mechanism and to explain the observed impact strength enhancement observed in the experiments, images of the truss core element during the tests are recorded. A method based on the edge detection algorithm is developed and applied to these images. The deforming profiles of one beam are extracted and it allows for calculating the length of beam. It is found that these lengths diminish to a critical value (due to compression and remain constant afterwards (because of significant bending. The comparison between quasi-static and impact tests shows that the beam were much more compressed under impact loading, which could be understood as the lateral inertia effect in dynamic bucking. Therefore, the impact strength enhancement of tetrahedral truss core sandwich panel can be explained by the delayed buckling of beam under impact (more compression reached, together with the strain hardening of base material.

  17. Measurement of deforming mode of lattice truss structures under impact loading

    Science.gov (United States)

    Liu, J.; Pattofatto, S.; Zhao, H.

    2012-08-01

    Lattice truss structures, which are used as a core material in sandwich panels, were widely investigated experimentally and theoretically. However, explanation of the deforming mechanism using reliable experimental results is almost rarely reported, particularly for the dynamic deforming mechanism. The present work aimed at the measurement of the deforming mode of lattice truss structures. Indeed, quasi-static and Split Hopkinson Pressure Bar (SHPB) tests have been performed on the tetrahedral truss cores structures made of Aluminum 3003-O. Global values such as crushing forces and displacements between the loading platens are obtained. However, in order to understand the deforming mechanism and to explain the observed impact strength enhancement observed in the experiments, images of the truss core element during the tests are recorded. A method based on the edge detection algorithm is developed and applied to these images. The deforming profiles of one beam are extracted and it allows for calculating the length of beam. It is found that these lengths diminish to a critical value (due to compression) and remain constant afterwards (because of significant bending). The comparison between quasi-static and impact tests shows that the beam were much more compressed under impact loading, which could be understood as the lateral inertia effect in dynamic bucking. Therefore, the impact strength enhancement of tetrahedral truss core sandwich panel can be explained by the delayed buckling of beam under impact (more compression reached), together with the strain hardening of base material.

  18. Determination of Velocity And Acceleration of Structural Deformation ...

    African Journals Online (AJOL)

    Journal of the Nigerian Association of Mathematical Physics ... Objects and engineering structures are subject to displacements resulting from ... is possible on the basis of cyclic measurements of changes in position of points determining the ...

  19. STUDYING DEFORMATIONS OF AN FLAT TRUSS STRUCTURE STATICALLY INDETERMINATED EXTERNALLY

    Directory of Open Access Journals (Sweden)

    Kirsanov Mikhail Nikolaevich

    2017-08-01

    Full Text Available A flat statically determinate parallel-chord truss structure has a cross-shaped grid and rests upon two rigid pin-bearing supports. Loads in bars are determined in a symbol form using the method of joint isolation by the computer mathematics Maple system. The peculiarity of the considered truss structure is its external static indeterminacy. In fact, all efforts and reactions of supports can be determined from the equilibrium conditions. But the inconvenience is necessary to consider the equilibrium of all the nodes of the truss. The Ritter cross-section method is not applicable to this truss structure. The sections that cut the truss into two parts and pass through the three rods, here exist only for several rods of the extreme panels. The purpose of this paper is to calculate a truss structure with a different number of panels in analytical and numerical form. Finite element calculation method with the use of software LISA 8.0 is applied. It’s noted that a truss structure is kinetically changeable when the number of spans is odd. The corresponding plan of probable velocities is given. In order to receive analytic dependence of deflection on the span number, the induction method and Maxwell-Moor formula has been applied. The operators of the compilation and solution of recurrence equations are involved in determining the general terms of the coefficient sequences. The formulas for calculation of loads in the most compressed bars of a truss structure were received.

  20. Atomic force microscopic study of the structure of high-density polyethylene deformed in liquid medium by crazing mechanism.

    Science.gov (United States)

    Bagrov, D V; Yarysheva, A Y; Rukhlya, E G; Yarysheva, L M; Volynskii, A L; Bakeev, N F

    2014-02-01

    A procedure has been developed for the direct atomic force microscopic (AFM) examination of the native structure of high-density polyethylene (HDPE) deformed in an adsorption-active liquid medium (AALM) by the crazing mechanism. The AFM investigation has been carried out in the presence of a liquid medium under conditions preventing deformed films from shrinkage. Deformation of HDPE in AALM has been shown to proceed through the delocalized crazing mechanism and result in the development of a fibrillar-porous structure. The structural parameters of the crazed polymer have been determined. The obtained AFM images demonstrate a nanosized nonuniformity of the deformation and enable one to observe the structural rearrangements that take place in the deformed polymer after removal of the liquid medium and stress relaxation. A structural similarity has been revealed between HDPE deformed in the AALM and hard elastic polymers. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

  1. 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

  2. Formation of diapiric structure in the deformation zone, central ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    The top of the rise is in a round shape and cut by vertical faults. The structure may possibly represent a diapir consisting of lower crustal rocks. The sediments .... pentinization of olivine clasts within the gabbro. These higher velocities near the base of layer 3 are indicative of serpentinized peridotites (Li Pichon et al 1972).

  3. Ultrasonic damage imaging of structural components with bulk and guided waves using match coefficients

    Science.gov (United States)

    Sternini, S.; Quattrocchi, A.; Montanini, R.; Lanza di Scalea, F.

    2017-04-01

    Damage imaging of structural components in the field of Non Destructive Evaluations (NDE) and Structural Health Monitoring (SHM) using ultrasonic waves is usually performed by conventional imaging techniques, such as DelayAnd-Sum (DAS), by back-propagating the recorded waveforms to identify locations and size of defects and damages. This technique results in sidelobes and artifacts that worsen the accuracy of the damage identification. Here we propose a novel imaging approach that derives from the well-known technique of Matched Field Processing (MFP), often used in underwater acoustics and seismology. In MFP, the source or damage is located by a matching procedure between measurements ("data vector") and expected responses ("replica vectors") computed for each point of the imaging volume. In this work, we apply this matching approach only to selected features extracted from the recorded waveforms. These features, for example time-of-flights or amplitudes, will be selected for multiple modes of propagation of the ultrasonic waves (longitudinal and shear in bulk waves, multiple guided modes in waveguides). By considering multiple features and multiple wave modes, it is possible to increase the performance of this matching procedure, which can be possibly further improved by also combining different signal frequencies and excitation sources in analogy with biomedical ultrasonic imaging. A correlation metric showing high computational efficiency in the image reconstruction process will be tested as matching coefficient. Applications of this imaging approach to a metallic plate with holes and simulated defects will be shown.

  4. Hydrostar Thermal and Structural Deformation Analyses of Antenna Array Concept

    Science.gov (United States)

    Amundsen, Ruth M.; Hope, Drew J.

    1998-01-01

    The proposed Hydrostar mission used a large orbiting antenna array to demonstrate synthetic aperture technology in space while obtaining global soil moisture data. In order to produce accurate data, the array was required to remain as close as possible to its perfectly aligned placement while undergoing the mechanical and thermal stresses induced by orbital changes. Thermal and structural analyses for a design concept of this antenna array were performed. The thermal analysis included orbital radiation calculations, as well as parametric studies of orbit altitude, material properties and coating types. The thermal results included predicted thermal distributions over the array for several cases. The structural analysis provided thermally-driven deflections based on these cases, as well as based on a 1-g inertial load. In order to minimize the deflections of the array in orbit, the use of XN70, a carbon-reinforced polycyanate composite, was recommended.

  5. 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.

  6. 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

    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...... intermittently. When the traction is terminated, stress relaxation occurs and number, size and orientation of subgrains are found to be constant. The subgrain structure freezes and only a minor clean-up of the dislocation structure is observed. When changing the tensile direction after pre-deformation in tension...

  7. Curved Displacement Transfer Functions for Geometric Nonlinear Large Deformation Structure Shape Predictions

    Science.gov (United States)

    Ko, William L.; Fleischer, Van Tran; Lung, Shun-Fat

    2017-01-01

    For shape predictions of structures under large geometrically nonlinear deformations, Curved Displacement Transfer Functions were formulated based on a curved displacement, traced by a material point from the undeformed position to deformed position. The embedded beam (depth-wise cross section of a structure along a surface strain-sensing line) was discretized into multiple small domains, with domain junctures matching the strain-sensing stations. Thus, the surface strain distribution could be described with a piecewise linear or a piecewise nonlinear function. The discretization approach enabled piecewise integrations of the embedded-beam curvature equations to yield the Curved Displacement Transfer Functions, expressed in terms of embedded beam geometrical parameters and surface strains. By entering the surface strain data into the Displacement Transfer Functions, deflections along each embedded beam can be calculated at multiple points for mapping the overall structural deformed shapes. Finite-element linear and nonlinear analyses of a tapered cantilever tubular beam were performed to generate linear and nonlinear surface strains and the associated deflections to be used for validation. The shape prediction accuracies were then determined by comparing the theoretical deflections with the finiteelement- generated deflections. The results show that the newly developed Curved Displacement Transfer Functions are very accurate for shape predictions of structures under large geometrically nonlinear deformations.

  8. 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...

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

    KAUST Repository

    El-Amin, Mohamed

    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.

  10. Characterization of the three‐dimensional structure of a metallic foam during compressive deformation

    National Research Council Canada - National Science Library

    MCDONALD, S. A; MUMMERY, P. M; JOHNSON, G; WITHERS, P. J

    2006-01-01

    .... The effect of the three‐dimensional cellular structure on the mechanisms of deformation suggests not only the position of large cell volumes to be very important in the local concentration of stress, but also the distribution of cell volumes of immediate neighbours.

  11. MAGNETO-THERMO-ELASTIC UNSTEADY DEFORMATION OF MULTILAYER STRUCTURES

    Directory of Open Access Journals (Sweden)

    Y. V. Mastinovky

    2015-12-01

    Full Text Available Modern electrical machines and devices, power generation facilities operate under complex unsteady magnetothermoelastic loads. Development of new insulating and damping coatings structures, shielding used in various electrical equipment requires new mathematical models and calculation methods for engineering practice. In this paper we consider a two-layer structure consisting of two piecewise-homogeneous non-ferromagnetic materials, one or both of which are electro-conductive. Volume forces action caused by the electromagnetic field and thermo-mechanical impact on the structure boundary is simulated. The original system of equations to solve the problem under study includes Maxwell equations and the generalized Ohm’s law for the determination of the electromagnetic field, the Duhamel-Neumann law – for the elastic field and the generalized Fourier heat equation – for the temperature field. These equations form a closed system and are the fundamental equations of magneto-thermo-elasticity. It is assumed that the speed of heat propagation is finite, and the magnetic field is constant. Assumptions are introduced to simplify the coupled system of thermo-elastic equations. The problem is solved numerically in a one-dimensional formulation applying the method of characteristics. Coupling conditions and method of calculation of unknown quantities in the nodal points of the grid area at the interface between layers are indicated. The proposed method of numerical and analytical solutions of problems under consideration allows, without making significant changes in the design scheme, to conduct numerical experiments. Setting up various geometric and thermo-physical parameters, it is possible to identify areas prone to damages under specified loads

  12. Features of structural response of vanadium crystallite under deformation in different crystallographic directions

    Science.gov (United States)

    Korchuganov, Aleksandr V.; Zolnikov, Konstantin P.; Kryzhevich, Dmitrij S.

    2017-10-01

    In the framework of the molecular dynamics method the features of structural rearrangements in vanadium crystallites under deformation in constrained conditions are investigated. Twins and edge dislocations are nucleated during the deformation of the crystallite. A large twin lamella is formed at stretching along the [112 ¯] direction. Stretching along [111] and [11 ¯0] results in the formation of numerous small fragments. These fragments are formed due to the growth and interaction of twins. Some of them have crystal orientations that differ from twin ones.

  13. Band Structure and Contact Resistance of Carbon Nanotubes Deformed by a Metal Contact

    Science.gov (United States)

    Hafizi, Roohollah; Tersoff, Jerry; Perebeinos, Vasili

    2017-11-01

    Capillary and van der Waals forces cause nanotubes to deform or even collapse under metal contacts. Using ab initio band structure calculations, we find that these deformations reduce the band gap by as much as 30%, while fully collapsed nanotubes become metallic. Moreover, degeneracy lifting due to the broken axial symmetry, and wave functions mismatch between the fully collapsed and the round portions of a CNT, lead to a 3 times higher contact resistance. The latter we demonstrate by contact resistance calculations within the tight-binding approach.

  14. On bulk singularity structures and all order α′ contact terms of BPS string amplitudes

    Directory of Open Access Journals (Sweden)

    Ehsan Hatefi

    2016-10-01

    Full Text Available The entire form of the amplitude of three SYM (involving two transverse scalar fields, a gauge field and a potential Cn−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 α′ 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 ∫d2z|1−z|a|z|b(z−z¯c(z+z¯3 on upper half plane as well.

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

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sun-Joo; Ren, Feifei; Zangerl-Plessl, Eva-Maria; Heyman, Sarah; Stary-Weinzinger, Anna; Yuan, Peng; Nichols, Colin G. (WU-MED); (Vienna)

    2016-08-15

    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 PIP2sensitivity. Here we show that introduction of a lipid-partitioning tryptophan at the second site (K62W) generates high PIP2sensitivity, 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 PIP2site and explaining the positive allostery between PL-binding and PIP2sensitivity.

  16. Mechanical deformation of atomic-scale metallic contacts: Structure and mechanisms

    DEFF Research Database (Denmark)

    Sørensen, Mads Reinholdt; Brandbyge, Mads; Jacobsen, Karsten Wedel

    1998-01-01

    We have simulated the mechanical deformation of atomic-scale metallic contacts under tensile strain using molecular dynamics and effective medium theory potentials. The evolution of the structure of the contacts and the underlying deformation mechanisms are described along with the calculated...... electronic conductance. Various defects such as intersecting stacking faults, local disorder, and vacancies are created during the deformation. Disordered regions act as weak spots that reduce the strength of the contacts. The disorder tends to anneal out again during the subsequent atomic rearrangements......, but vacancies can be permanently present. The transition states and energies for slip mechanisms have been determined using the nudged elastic band method, and we find a size-dependent crossover from a dislocation-mediated slip to a homogeneous slip when the contact diameter becomes less than a few nm. We show...

  17. Lifetime Reliability Estimate and Extreme Permanent Deformations of Randomly Excited Elasto-Plastic Structures

    DEFF Research Database (Denmark)

    Nielsen, Søren R.K.; Sørensen, John Dalsgaard; Thoft-Christensen, Palle

    1983-01-01

    A method is presented for life-time reliability' estimates of randomly excited yielding systems, assuming the structure to be safe, when the plastic deformations are confined below certain limits. The accumulated plastic deformations during any single significant loading history are considered...... to be the outcome of identically distributed, independent stochastic variables,for which a model is suggested. Further assuming the interarrival times of the elementary loading histories to be specified by a Poisson process, and the duration of these to be small compared to the designed life-time, the accumulated...... plastic deformation during several loadings can be modelled as a filtered Poisson process. Using the Markov property of this quantity the considered first-passage problem as well as the related extreme distribution problems are then solved numerically, and the results are compared to simulation studies....

  18. Influence of structural heterogeneity on the structural coarsening during annealing of polycrystalline Ni subjected to dynamic plastic deformation

    DEFF Research Database (Denmark)

    Zhang, H.W.; Luo, Z.P.; Hansen, Niels

    2015-01-01

    The structural heterogeneity of a polycrystalline Ni subjected to dynamic plastic deformation to a strain of 2.3 was characterized, and its influence on the structural coarsening behaviour during post annealing was investigated. Structural heterogeneity on the large scale manifests itself...... orientation. In contrast HMRs contain both low and high angle boundaries (>15o) and the texture is mixed with close to the compression axis. During annealing, LMRs coarsen uniformly and recrystallization nucleation is difficult to form. In HMRs, the structural evolution is heterogeneous...... and recrystallization nuclei are readily formed. The importance of structural heterogeneity during structural design for high performance nanostructure was highlighted....

  19. 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.

  20. 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.

  1. 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

  2. Structural and mechanical properties of a giomer-based bulk fill restorative in different curing conditions

    Directory of Open Access Journals (Sweden)

    Mustafa Sarp Kaya

    2018-01-01

    Full Text Available ABSTRACT Objective: The main goal of this study was to compare the polymerization degree of bulk-fill giomer resin cured with three different light-curing units (LCUs: a polywave third-generation (Valo; a monowave (DemiUltra: DU; and a second-generation LED (Optima 10: Opt LCUs by using structural and mechanical properties. Material and methods: Giomer samples of 2 and 4 mm cured with three LCUs were employed in vitro analysis. The degree of curing (DC% was determined with Fourier-Transform Infrared Spectroscopy (FTIR. Microstructural features were observed with scanning electron microscopy (SEM. Flexural strength (FS, compression strength (CS, elastic modulus and fracturing strain were determined for mechanical properties. Surface microhardness (SMH values were also measured. Oneway ANOVA, two-way analysis of variance and Tukey multiple comparison tests were used for statistically analyzing the FS and SMH. Results: DC% values were 58.2, 47.6, and 39.7 for the 2 mm samples cured with DU, Opt., and Valo LCUs, respectively. DC% values of the 4 mm samples were 50.4, 44.6, and 38.2 for DU, Opt, and Valo, respectively. SMH values were Valo, Optstructural defects and physical frailties on restorations due to lower degree of polymerization.

  3. 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...

  4. Deformation analysis and prediction of bank protection structure with river level fluctuations

    Science.gov (United States)

    Hu, Rui; Xing, Yixuan

    2017-04-01

    Bank structure is an important barrier to maintain the safety of the embankment. The deformation of bank protection structure is not only affected by soil pressure caused by the excavation of the riverway, but also by the water pressure caused river water level fluctuations. Thus, it is necessary to establish a coupled soil-water model to analyze the deformation of bank structure. Based on Druck-Prager failure criteria and groundwater seepage theory, a numerical model of bank protection structure with consideration of the pore water pressure of soil mass is established. According to the measured river level data with seasonal fluctuating, numerical analysis of the deformation of bank protection structure is implemented. The simulation results show that the river water level fluctuation has clear influence on the maximum lateral displacement of the pile. Meanwhile, the distribution of plastic zone is related to the depth of groundwater level. Finally, according to the river water level data of the recent ten years, we analyze the deformation of the bank structure under extreme river level. The result shows that, compared with the scenario of extreme high river level, the horizontal displacement of bank protection structure is larger (up to 65mm) under extreme low river level, which is a potential risk to the embankment. Reference Schweiger H F. On the use of drucker-prager failure criteria for earth pressure problems[J]. Computers and Geotechnics, 1994, 16(3): 223-246. DING Yong-chun,CHENG Ze-kun. Numerical study on performance of waterfront excavation[J]. Chinese Journal of Geotechnical Engineering,2013,35(2):515-521. Wu L M, Wang Z Q. Three gorges reservoir water level fluctuation influents on the stability of the slope[J]. Advanced Materials Research. Trans Tech Publications, 2013, 739: 283-286.

  5. "Work-Hardenable" ductile bulk metallic glass.

    Science.gov (United States)

    Das, Jayanta; Tang, Mei Bo; Kim, Ki Buem; Theissmann, Ralf; Baier, Falko; Wang, Wei Hua; Eckert, Jürgen

    2005-05-27

    Usually, monolithic bulk metallic glasses undergo inhomogeneous plastic deformation and exhibit poor ductility (glass, which exhibits high strength of up to 2265 MPa together with extensive "work hardening" and large ductility of 18%. Significant increase in the flow stress was observed during deformation. The "work-hardening" capability and ductility of this class of metallic glass is attributed to a unique structure correlated with atomic-scale inhomogeneity, leading to an inherent capability of extensive shear band formation, interactions, and multiplication of shear bands.

  6. Formation of Quenching Structures in the Steel 35 by Deform Cutting

    Directory of Open Access Journals (Sweden)

    A. G. Degtyareva

    2014-01-01

    Full Text Available In industry different methods of surface hardening are widely used to increase reliability and durability of friction unit parts. Among these methods are areas of focus based on deformcutting technology (DC i.e. method of chip-free mechanical treatment.It is shown that DC method allows us to produce through- or partial-hardening surface layers of a large thickness (0,4…1.5mm on steel with no additional heat sources. The standard metal-cutting equipment and common tools are used for deform-cutting process.The significant heat generation in the deform-cutting zone and mechanical effect from the tool allow us to heat undercut layers to the phase transformation point to have the hardening structure as a result of heat removal to the cold balk. The hardening structure formation occurs at significant heating and cooling rate (106C/c with large degrees and rates of strain.The deform-cutting modes and working face tool grinding determine the type and properties of the hardening structure. To produce the hardening structure would require the heat transfer and force action augmentation while treatment.These researches deal with through- and partial surface hardening samples produced by turning steel 35 shafts. While through hardening the phase transformation carry among the whole thickness of the undercut layer; while partial hardening the hardening interlayer formed on the side of the cutting tool contact.The depth of hardening zone of samples with through hardening layers is 0,5 mm; the depth of hardening zone of partial hardening samples is 0,8 mm. Micro-hardness of the through hardening layers is 653 HV0,1 and 485 HV0,1 for the partial hardening layers. The metallographic analysis shows that the hardening zone formed while deform cutting has disperse structure; there are ferrite ghosts in it.The tempering at temperatures of 200 – 700C showed that the micro-hardness of the hardening structures formed while deform cutting is larger than the micro

  7. 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.

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

    DEFF Research Database (Denmark)

    Hansen, Niels; Kuhlmann-Wilsdorf, D.

    1986-01-01

    , correspondingly leaving the major fraction of the volume free of dislocations. The value of R decreases in the following order: pile-ups to dipolar mats, Taylor lattices, tilt and dipolar walls to dislocation cell structures. This is the same order in which dislocation structures tend to develop with increasing......” 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....

  9. 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.

  10. 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.

  11. A nonlinear deformed su(2) algebra with a two-colour quasitriangular Hopf structure

    CERN Document Server

    Bonatsos, Dennis; Kolokotronis, P; Ludu, A; Quesne, C

    1996-01-01

    Nonlinear deformations of the enveloping algebra of su(2), involving two arbitrary functions of J_0 and generalizing the Witten algebra, were introduced some time ago by Delbecq and Quesne. In the present paper, the problem of endowing some of them with a Hopf algebraic structure is addressed by studying in detail a specific example, referred to as ${\\cal A}^+_q(1)$. This algebra is shown to possess two series of (N+1)-dimensional unitary irreducible representations, where N=0, 1, 2, .... To allow the coupling of any two such representations, a generalization of the standard Hopf axioms is proposed by proceeding in two steps. In the first one, a variant and extension of the deforming functional technique is introduced: variant because a map between two deformed algebras, su_q(2) and ${\\cal A}^+_q(1)$, is considered instead of a map between a Lie algebra and a deformed one, and extension because use is made of a two-valued functional, whose inverse is singular. As a result, the Hopf structure of su_q(2) is car...

  12. Predicting welding distortion in a panel structure with longitudinal stiffeners using inherent deformations obtained by inverse analysis method.

    Science.gov (United States)

    Liang, Wei; Murakawa, Hidekazu

    2014-01-01

    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.

  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. Structure and Heterogeneous Deformation in the 1989-90 Loma Prieta Aftershock Sequence

    Science.gov (United States)

    Twiss, R. J.; Unruh, J. R.

    2002-12-01

    The 1989 Loma Prieta earthquake occurred on a blind, southwest-dipping fault zone beneath the Santa Cruz mountains in northern California. We divided the aftershock sequence into 17 spatially identifiable clusters of events and subdivided the clusters into a total of 33 subsets by requiring deformational homogeneity of the subsets. We inverted focal mechanisms using a micropolar kinematic model (Twiss et al. 1991, 1993) to evaluate the deformation and its distribution, and we examined the spatial distributions of hypocenters to infer details of the local structure. Our results show the following: The deformation is dominated by a combination of near-horizontal plane strain and crustal thickening, with the maximum contraction rate axis (d3) subhorizontal NNE, and the maximum extension rate axis (d1) either subhorizontal ESE or subvertical, although a number of solutions occur with one or both principal axes having a moderate plunge. Aftershocks below a transition depth of 4 - 6 km define three planar segments of the fault forming a sigmoidal contractional bend in the fault zone, consistent with the youthful, high topography of this region. The southern segment is nearly parallel to the local Pacific-Sierra Nevada plate motion vector, and the central, and to a lesser extent the northern, segments are in a contractional orientation. The inversion solutions are consistent, giving in general a higher vertical component of deformation and a larger reverse component of resolved shear on the fault for fault segments in a more contractional orientation. Above the transition depth, aftershocks are less well aligned along the three fault zone segments. Generally they define structures in a more contractional orientation relative to the plate motion vector, and they dominantly accommodate a crustal thickening deformation. Deformation inferred from the inversion solutions is locally heterogeneous, with events associated with different deformation geometries commonly intermixed

  15. 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...... to be a 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....

  16. Mercury: a prediction for bulk chemical composition and internal structure in readiness for new MESSENGER data

    Science.gov (United States)

    Prentice, A. J.

    2008-12-01

    The MESSENGER spacecraft has confirmed that Mercury's magnetic field is dominantly dipolar and due to an active dynamo in a molten outer core (Solomon et al, 2008 Science 321 59). An energy source is needed to maintain this dynamo. Either liquid iron is freezing at the surface of an inner solid core (as proposed here) or solid iron is precipitating within an outer sulphur-rich core (Chen et al, 2008 GRL 35 L07201). If the outer core does not contain sulphur and consists solely of pure metal (Fe, Ni, Cr,..), then an active dynamo is inconsistent with previous numerical models for the radiogenic thermal evolution of the planet. Those earlier models found that the present temperature at the core/mantle boundary (CMB) is ~ 500 K below the melting temperature of metal ~ 2030 K for a CMB pressure of 70 kbar. The earlier calculations were based on low lunar abundances of U and Th. Here I present a new model for the bulk chemical composition, thermal evolution and current internal structure of Mercury. The model is based on the modern Laplacian theory of solar system origin (Prentice, 1978 Moon Planets 19 341; 2001 Earth Moon & Planets 87 11; 2006 Publ. Astron. Soc. Aust. (PASA) 23 1; 2008 - URL below). A key feature of this theory is that the planets formed from a concentric system of gas rings (n = 0, 1, 2,..) that were shed by the contracting protosolar cloud. The temperatures Tn of the rings scale with mean orbital radius Rn closely as Tn ~ Rn-0.9. Mercury plays a crucial role in calibrating this relationship because of a condensation process of metal/silicate fractionation (Lewis, 1972 EPSL 15 286). Choosing Tn ~ 1630 K for mean orbit gas ring pressure of 0.17 bar, the condensate consists mostly of Fe-Ni-Cr (mass fraction 0.671), gehlenite (0.190) and Mg-silicates (0.081). It has mean density 5.30 g/cm3. Na, K and S are absent. The mass fractions of U and Th, namely 5.66 × 10-8 & 2.08 × 10-7, are a factor of 4.3 times greater than those of the proto-Earth condensate

  17. Deformation Structures Along mid-crustal Shear Zones: What are Field Evidences for Ancient Tremor and Slip Activity?

    Science.gov (United States)

    Herwegh, M.; Buckingham, T.; Pfiffner, A.

    2009-12-01

    Large-scale shear zones like thrusts faults, detachments or strike slip faults accommodate a considerable amount of deformation of the lithosphere. From surface based earthquake and modern GPS monitoring systems we know that deformation in shear zones may alternate between stages of continuous steady state creep and transient stages comprising instantaneous seismically active deformation events. One way to learn more about the physical processes related to tremor and slip activity is the study of deformation structures of formerly active crustal faults, which have meanwhile been exposed at the surface. In light of tremor and slip, particularly brittle deformation associated with fluid activity are interpreted to reflect the major deformation processes. In this study, we present a series of deformation structures from major thrust zones of the Helvetic Alps all indicating a close interplay between fluid flux and brittle deformation interlinked with stages of ductile deformation. Among others, prominent examples are arrays of synkinematic veins, which formed by cycles of hydrofracturing, mineral precipitation and ductile deformation. Interestingly, these structures are concentrated at paleo-depth intervals between 8-13 km, i.e., at crustal levels where recent seismic activity in orogens often is concentrated, while they are less abundant at greater depths. Are we looking here at the source of the processes manifest at the surface by the measured tremor and slip activity? The goal of the talk will be to demonstrate a series of deformation structures, which potentially can be attributed to transient deformation, and to address the question whether or not they can be used as indicators for tremor and slip activity at depth.

  18. Use of complementary neutron techniques in studying the effect of a solid/liquid interface on bulk solution structures

    Energy Technology Data Exchange (ETDEWEB)

    Butler, P.D.; Hamilton, W.A.; Magid, L.J. [and others

    1996-12-31

    By appropriate combination of neutron scattering techniques, it is possible to obtain structural information at various distances from a solid/liquid interface and thus probe in some detail how the surface structures evolve into bulk structures. We have used neutron reflectometry (NR) with a newly developed shear cell, near surface small angle neutron scattering (NSSANS) again in combination with the new shear cell, and regular small angle neutron scattering (SANS) with a standard Couette shear cell to probe the structures formed in our aqueous surfactant systems and how they react to a flow field, particularly in the near surface region of a solid/liquid interface. We present data for a 20mM aqueous solutions of 70% cetyltrimethylammonium 3,5-dichlorobenzoate (abbreviated CTA3,5ClBz) and 30% CTAB. This system forms a very viscoelastic solution containing long threadlike micelles. NR only probes to a depth of about 0.5 {mu}m from the surface in these systems and clearly indicates that adsorbed onto the surface is, surfactant layer which is insensitive to shear. The depth probed by the NSSANS is on the order of 20-30 {mu}m and is determined by the transmission of the sample, the angle of incidence, and the wavelength. In this region, the rods align under shear into a remarkably well ordered hexagonal crystal. The SANS from the Couette cell averages over the entire sample, so that the signal is dominated by scattering from the bulk. While the near surface hexagonal structure is clearly visible, these data are not consistent with the crystal structure persisting throughout the bulk, leading to the postulate that the bulk structure is a two dimensional (2D) liquid where the rods align with the flow, but do not order in the other two dimensions.

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

    Energy Technology Data Exchange (ETDEWEB)

    Chimi, Yasuhiro, E-mail: chimi.yasuhiro@jaea.go.jp [Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Kitsunai, Yuji [Nippon Nuclear Fuel Development, 2163 Narita-cho, Oarai-machi, Higashi-ibaraki-gun, Ibaraki 311-1313 (Japan); Kasahara, Shigeki [Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Chatani, Kazuhiro; Koshiishi, Masato [Nippon Nuclear Fuel Development, 2163 Narita-cho, Oarai-machi, Higashi-ibaraki-gun, Ibaraki 311-1313 (Japan); Nishiyama, Yutaka [Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan)

    2016-07-15

    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. - Highlights: • Visible step structures depend on the neutron dose and the applied strain. • Local strain at grain boundaries was accumulated with the neutron dose. • Oxide thickness increases with neutron dose and local strain at grain boundaries. • No penetrative oxidation was observed along grain boundaries or surface steps.

  20. A Deformed Shape Monitoring Model for Building Structures Based on a 2D Laser Scanner

    Directory of Open Access Journals (Sweden)

    Hyo Seon Park

    2013-05-01

    Full Text Available High-rise buildings subjected to lateral loads such as wind and earthquake loads must be checked not to exceed the limits on the maximum lateral displacement or the maximum inter-story drift ratios. In this paper, a sensing model for deformed shapes of a building structure in motion is presented. The deformed shape sensing model based on a 2D scanner consists of five modules: (1 module for acquiring coordinate information of a point in a building; (2 module for coordinate transformation and data arrangement for generation of time history of the point; (3 module for smoothing by adjacent averaging technique; (4 module for generation of the displacement history for each story and deformed shape of a building, and (5 module for evaluation of the serviceability of a building. The feasibility of the sensing model based on a 2D laser scanner is tested through free vibration tests of a three-story steel frame structure with a relatively high slenderness ratio of 5.0. Free vibration responses measured from both laser displacement sensors and a 2D laser scanner are compared. In the experimentation, the deformed shapes were obtained from three different methods: the model based on the 2D laser scanner, the direct measurement based on laser displacement sensors, and the numerical method using acceleration data and the displacements from GPS. As a result, it is confirmed that the deformed shape measurement model based on a 2D laser scanner can be a promising alternative for high-rise buildings where installation of laser displacement sensors is impossible.

  1. Superposed ruptile deformational events revealed by field and VOM structural analysis

    Science.gov (United States)

    Kumaira, Sissa; Guadagnin, Felipe; Keller Lautert, Maiara

    2017-04-01

    Virtual outcrop models (VOM) is becoming an important application in the analysis of geological structures due to the possibility of obtaining the geometry and in some cases kinematic aspects of analyzed structures in a tridimensional photorealistic space. These data are used to gain quantitative information on the deformational features which coupled with numeric models can assist in understands deformational processes. Old basement units commonly register superposed deformational events either ductile or ruptile along its evolution. The Porongos Belt, located at southern Brazil, have a complex deformational history registering at least five ductile and ruptile deformational events. In this study, we presents a structural analysis of a quarry in the Porongos Belt, coupling field and VOM structural information to understand process involved in the last two deformational events. Field information was acquired using traditional structural methods for analysis of ruptile structures, such as the descriptions, drawings, acquisition of orientation vectors and kinematic analysis. VOM was created from the image-based modeling method through photogrammetric data acquisition and orthorectification. Photogrammetric data acquisition was acquired using Sony a3500 camera and a total of 128 photographs were taken from ca. 10-20 m from the outcrop in different orientations. Thirty two control point coordinates were acquired using a combination of RTK dGPS surveying and total station work, providing a precision of few millimeters for x, y and z. Photographs were imported into the Photo Scan software to create a 3D dense point cloud from structure from-motion algorithm, which were triangulated and textured to generate the VOM. VOM was georreferenced (oriented and scaled) using the ground control points, and later analyzed in OpenPlot software to extract structural information. Data was imported in Wintensor software to obtain tensor orientations, and Move software to process and

  2. Band structure, band offsets, substitutional doping, and Schottky barriers of bulk and monolayer InSe

    Science.gov (United States)

    Guo, Yuzheng; Robertson, John

    2017-09-01

    We present a detailed study of the electronic structure of the layered semiconductor InSe. We calculate the band structure of the monolayer and bulk material using density functional theory, hybrid functionals, and G W . The band gap of the monolayer InSe is calculated to be 2.4 eV in screened exchange hybrid functional, close to the experimental photoluminescence gap. The electron affinities and band offsets are calculated for vertical stacked-layer heterostructures, and are found to be suitable for tunnel field effect transistors (TFETs) in combination with WS e2 or similar. The valence-band edge of InSe is calculated to lie 5.2 eV below the vacuum level, similar to that for the closed shell systems HfS e2 or SnS e2 . Hence InSe would be suitable to act as a p -type drain in the TFET. The intrinsic defects are calculated. For Se-rich layers, the Se adatom (interstitial) is found to be the most stable defect, whereas for In-rich layers, the Se vacancy is the most stable for the neutral state. Antisites tend to have energies just above those of vacancies. The Se antisite distorts towards a bond-breaking distortion as in the EL2 center of GaAs. Both substitutional donors and acceptors are calculated to be shallow, and effective dopants. They do not reconstruct to form nondoping configurations as occurs in black phosphorus. Finally, the Schottky barriers of metals on InSe are found to be strongly pinned by metal induced gap states (MIGS) at ˜0.5 eV above the valence-band edge. Any interfacial defects would lead to a stronger pinning at a similar energy. Overall, InSe is an effective semiconductor combining the good features of 2D (lack of dangling bonds, etc.) with the good features of 3D (effective doping), which few others achieve.

  3. Local deformation method for measuring element tension in space deployable structures

    Directory of Open Access Journals (Sweden)

    Belov Sergey

    2017-01-01

    Full Text Available The article describes the local deformation method to determine the tension of cord and thin membrane elements in space deployable structure as antenna reflector. Possible measuring instrument model, analytical and numerical solutions and experimental results are presented. The boundary effects on measurement results of metallic mesh reflector surface tension are estimated. The study case depicting non-uniform reflector surface tension is considered.

  4. Structure and phase composition of tempered martensite steel after severe plastic deformation

    Science.gov (United States)

    Nikonenko, Alisa; Popova, Natalya; Nikonenko, Elena; Sizonenko, Nina; Koneva, Nina

    2017-11-01

    The paper presents transmission electron microscopic investigations of the structure and X-ray diffraction analysis of the phase composition of tempered martensite steel of 0.06Mo-1V-1Nb-Fe type deformed via the Equal Channel Angular Extrusion (ECAE) technique. As it turns, the ECAE has an effect on the morphology and phase composition of the alloy. Its faulted structure, dislocation density, internal stresses, and the size of coherent scattering areas are investigated in this paper. A special attention is paid to misorientations between grains. It is shown that in its original state (before ECAE), the steel structure represents tempered lath martensite and grains of α-phase. Carbide particles of M2C type are present inside these grains and at their boundaries. ECAE deformation results in a complete fragmentation of lath martensite and grinding of α-phase grains. A partial fracture and dissolution of carbide particles occurs. Carbon releases from carbides and localizes on defects of the crystal lattice. ECAE deformation increases misorientations in lath martensite (up to 25-30 degrees) and nucleation of micrograins in former grains of α-phase.

  5. 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...

  6. 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

  7. Recovery of the bulk-like electronic structure of manganese phthalocyanine beyond the first monolayer on Bi2Te3

    Science.gov (United States)

    Hewitt, A. S.; Boltersdorf, J.; Maggard, P. A.; Dougherty, D. B.

    2017-08-01

    The evolution of electronic structure of manganese phthalocyanine on Bi2Te3 shows a transition to a bulk-like aspect abruptly after completion of the first layer. This allows the inference that, in the first layer, there is charge transfer and electronic hybridization involving the occupied Mn-derived d orbitals of the molecule into the conduction band of the substrate. The charge transfer coupling is seen using angle-resolved ultraviolet photoelectron spectroscopy by monitoring the evolution of work function and band structure with increasing molecular film thickness. The electronic structure in the second layer is more bulk-like as indicated by the reappearance of well-known low energy d orbitals that were depopulated in the first layer. Scanning tunneling microscopy shows that the transition to bulk like behavior is also reflected in film structure as a transition from a unique disordered monolayer to a locally ordered and dense second layer. These observations are relevant to ongoing efforts to control topological insulator interfaces especially for spintronics applications.

  8. Structure and property evaluation of a vacuum plasma sprayed nanostructured tungsten-hafnium carbide bulk composite

    NARCIS (Netherlands)

    Rea, K. E.; Viswanathan, V.; Kruize, A.; De Hosson, J. Th. M.; O'Dell, S.; McKechnie, T.; Rajagopalan, S.; Vaidyanathan, R.; Seal, S.; O’Dell, S.

    2008-01-01

    Vacuum plasma spray (VPS) forming of tungsten-based metal matrix nanocomposites (MMCs) has shown to be a cost effective and time saving method for the formation of bulk monolithic nanostructured then no-mechanical components. Spray drying of powder feedstock appears to have a significant effect on

  9. Bulk and Surface Structures of Palladium-Modified Copper-Zinc Oxides ex Hydroxycarbonate Precursors

    NARCIS (Netherlands)

    López Granados, M.; Melián-Cabrera, I.; Fierro, J.L.G.

    2002-01-01

    (Pd)-Cu-Zn ex hydroxycarbonate precursors were prepared and characterized by several bulk and surface techniques. A palladium-free Cu-Zn precursor (CZ) was prepared by coprecipitation. Two Pd-Cu-Zn samples were prepared by coprecipitation (PCZ-CP) and sequential precipitation (PCZ-SP). It is shown

  10. Damage detection of concrete masonry structures by enhancing deformation measurement using DIC

    Science.gov (United States)

    Bolhassani, Mohammad; Rajaram, Satish; Hamid, Ahmad A.; Kontsos, Antonios; Bartoli, Ivan

    2016-04-01

    This study focuses on deformability and damage detection of a concrete masonry wall. It employed point-to-point traditional strain gages and full-field measurement technique using digital image correlation (DIC) to investigate the damage and deformability of a partially grouted (PG) reinforced masonry wall. A set of ungrouted and grouted assemblages and full-scale concrete masonry shear wall were constructed and tested under displacement control loading. The wall was constructed according with masonry standards joint committee (MSJC 2013) and tested under constant vertical compression load and horizontal lateral load using quasi-static displacement procedure. The DIC method was used to determine non-uniform strain contours on the assemblages. This method was verified by comparing strains along the selected directions with traditional TML gage results. After a successful comparison, the method was used to investigate the state of damage and deformability of the wall specimen. Panel deformation, crack pattern, displacement at the top, and the base strain of the wall were captured using full-field measurement and results were in a good agreement with traditional strain gages. It is concluded that full-filed measurements using DIC is promising especially when the test specimens experience inelastic deformation and high degree of damage. The ability to characterize and anticipate failure mechanisms of concrete masonry systems by depicting strain distribution, categorizing structural cracks and investigating their effects on the behavior of the wall were also shown using DIC. In addition to monitoring strains across the gage length, the DIC method provided full-field strain behavior of the test specimens and revealed strain hotspots at locations that corresponded to failure.

  11. On new bulk singularity structures, RR couplings in the asymmetric picture and their all order α{sup '} corrections

    Energy Technology Data Exchange (ETDEWEB)

    Hatefi, Ehsan [Queen Mary University of London, Centre for Research in String Theory, School of Physics and Astronomy, London (United Kingdom); TU Wien, Institute for Theoretical Physics, Vienna (Austria)

    2017-08-15

    We have analyzed in detail four and five point functions of the string theory amplitudes, including a closed string Ramond-Ramond (RR) in an asymmetric picture and either two or three transverse scalar fields in both IIA and IIB. The complete forms of these S-matrices are derived and these asymmetric S-matrices are also compared with their own symmetric results. This leads us to explore two different kinds of bulk singularity structures as well as various new couplings in the asymmetric picture of the amplitude in type II string theory. All order α{sup '} higher derivative corrections to these new couplings have been discovered as well. Several remarks for these two new bulk singularity structures and for contact interactions of the S-matrix have also been made. (orig.)

  12. On new bulk singularity structures, RR couplings in the asymmetric picture and their all order α ' corrections

    Science.gov (United States)

    Hatefi, Ehsan

    2017-08-01

    We have analyzed in detail four and five point functions of the string theory amplitudes, including a closed string Ramond-Ramond (RR) in an asymmetric picture and either two or three transverse scalar fields in both IIA and IIB. The complete forms of these S-matrices are derived and these asymmetric S-matrices are also compared with their own symmetric results. This leads us to explore two different kinds of bulk singularity structures as well as various new couplings in the asymmetric picture of the amplitude in type II string theory. All order α ' higher derivative corrections to these new couplings have been discovered as well. Several remarks for these two new bulk singularity structures and for contact interactions of the S-matrix have also been made.

  13. Soft electronic structure modulation of surface (thin-film) and bulk (ceramics) morphologies of TiO{sub 2}-host by Pb-implantation: XPS-and-DFT characterization

    Energy Technology Data Exchange (ETDEWEB)

    Zatsepin, D.A. [M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 620990 Yekaterinburg (Russian Federation); Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation); Boukhvalov, D.W., E-mail: danil@hanyang.ac.kr [Department of Chemistry, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Theoretical Physics and Applied Mathematics Department, Ural Federal University, Mira Street 19, 620002 Yekaterinburg (Russian Federation); Gavrilov, N.V. [Institute of Electrophysics, Russian Academy of Sciences, Ural Branch, 620990 Yekaterinburg (Russian Federation); Zatsepin, A.F. [Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation); Shur, V.Ya.; Esin, A.A. [Institute of Natural Sciences, Ural Federal University, 51 Lenin Ave, 620000 Yekaterinburg (Russian Federation); Kim, S.S. [School of Materials Science and Engineering, Inha University, Incheon 402-751 (Korea, Republic of); Kurmaev, E.Z. [M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 620990 Yekaterinburg (Russian Federation); Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation)

    2017-04-01

    Highlights: • Experiment and theory demonstrate significant difference between patterns of Pb-ion implantation in TiO{sub 2}. • In bulk TiO{sub 2} Pb-impurities leads formation of PbO phase. • On the surface of TiO{sub 2}:Pb occur formation of PbxOy configurations. • In both bulk and surface TiO{sub 2}:Pb occur decreasing of the bandgap by shift of valence band about 1 eV up. - Abstract: The results of combined experimental and theoretical study of substitutional and clustering effects in the structure of Pb-doped TiO{sub 2}-hosts (bulk ceramics and thin-film morphologies) are presented. Pb-doping of the bulk and thin-film titanium dioxide was made with the help of pulsed ion-implantation without posterior tempering (Electronic Structure Modulation Mode). The X-ray photoelectron spectroscopy (XPS) qualification of core-levels and valence bands and Density-Functional Theory (DFT) calculations were employed in order to study the yielded electronic structure of Pb-ion modulated TiO{sub 2} host-matrices. The combined XPS-and-DFT analysis has agreed definitely with the scenario of the implantation stimulated appearance of PbO-like structures in the bulk morphology of TiO{sub 2}:Pb, whereas in thin-film morphology the PbO{sub 2}-like structure becomes dominating, essentially contributing weak O/Pb bonding (Pb{sub x}O{sub y} defect clusters). The crucial role of the oxygen hollow-type vacancies for the process of Pb-impurity “insertion” into the structure of bulk TiO{sub 2} was pointed out employing DFT-based theoretical background. Both experiment and theory established clearly the final electronic structure re-arrangement of the bulk and thin-film morphologies of TiO{sub 2} because of the Pb-modulated deformation and shift of the initial Valence Base-Band Width about 1 eV up.

  14. 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

  15. Comparative analysis of the structure of palladium-based bulk metallic glasses prepared by treatment of melts with flux

    Science.gov (United States)

    Louzguine-Luzgin, D. V.; Bazlov, A. I.; Churyumov, A. Yu.; Georgarakis, K.; Yavari, A. R.

    2013-10-01

    A comparative analysis has been presented of structural features of palladium-based bulk metallic glasses prepared by argon gas casting into a copper mold after treatment of melts with a flux and studied using X-ray synchrotron radiation. The radial distribution functions have been calculated. The short-range order (in the first and second coordination shells) and the medium-range order (from the third to several subsequent coordination shells) in atomic arrangement have been analyzed.

  16. Investigation of the carbon dioxide sorption capacity and structural deformation of coal

    Energy Technology Data Exchange (ETDEWEB)

    Hur, Tae-Bong; Fazio, James; Romanov, Vyacheslav; Harbert, William

    2010-01-01

    Due to increasing atmospheric CO2 concentrations causing the global energy and environmental crises, geological sequestration of carbon dioxide is now being actively considered as an attractive option to mitigate greenhouse gas emissions. One of the important strategies is to use deep unminable coal seams, for those generally contain significant quantities of coal bed methane that can be recovered by CO2 injection through enhanced coal bed natural gas production, as a method to safely store CO2. It has been well known that the adsorbing CO2 molecules introduce structural deformation, such as distortion, shrinkage, or swelling, of the adsorbent of coal organic matrix. The accurate investigations of CO2 sorption capacity as well as of adsorption behavior need to be performed under the conditions that coals deform. The U.S. Department of Energy-National Energy Technology Laboratory and Regional University Alliance are conducting carbon dioxide sorption isotherm experiments by using manometric analysis method for estimation of CO2 sorption capacity of various coal samples and are constructing a gravimetric apparatus which has a visual window cell. The gravimetric apparatus improves the accuracy of carbon dioxide sorption capacity and provides feasibility for the observation of structural deformation of coal sample while carbon dioxide molecules interact with coal organic matrix. The CO2 sorption isotherm measurements have been conducted for moist and dried samples of the Central Appalachian Basin (Russell County, VA) coal seam, received from the SECARB partnership, at the temperature of 55 C.

  17. A structurally based viscoelastic model for passive myocardium in finite deformation

    Science.gov (United States)

    Shen, Jing Jin

    2016-09-01

    This paper discusses the finite-deformation viscoelastic modeling for passive myocardium tissue. The formulations established can also be applied to model other fiber-reinforced soft tissue. Based on the morphological structure of the myocardium, a specific free-energy function is constructed to reflect its orthotropicity. After deriving the stress-strain relationships in the simple shear deformation, a genetic algorithm is used to optimally estimate the material parameters of the myocardial constitutive equation. The results show that the proposed myocardial model can well fit the shear experimental data. To validate the viscoelastic model, it is used to predict the creep and the dynamic responses of a cylindrical model of the left ventricle. Upon comparing the results calculated by the proven myocardial elastic model with those by the viscoelastic model, the merits of the latter are discussed.

  18. 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.

  19. Mesoscale structural characterization within bulk materials by high-energy X-ray microdiffraction

    DEFF Research Database (Denmark)

    Lienert, U.; Poulsen, H.F.; Kvick, Å.

    2001-01-01

    A novel diffraction technique for the local three-dimensional characterization within polycrystalline bulk materials is presented. The technique uses high-energy synchrotron radiation (40 keV ... that provide the required intensity and spatial resolution perpendicular to the incident beam. A focus size of 1.2 mum was achieved. Modified crossed-beam techniques are being developed that define the longitudinal resolution, i.e., the component of the gauge volume parallel to the incident beam. We present...

  20. 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

  1. Superlocalization and Formation of Grain Structure in Ni3ge Single Crystals with Different Orientations of Deformation Axes

    Science.gov (United States)

    Solov'eva, Yu. V.; Lipatnikova, Ya. D.; Starenchenko, S. V.; Solov'ev, A. N.; Starenchenko, V. A.

    2017-09-01

    The paper describes the influence of orientation of Ni3Ge single crystal deformation axes on the high-temperature superlocalization of plastic deformation. Mechanical properties of single crystals with different orientations are studied in this paper as well as the slip traces and the evolution of the dislocation structure. Based on these investigations, the observing conditions are described for the superlocalization bands and the formation of the grain structure in local areas of the original single crystal.

  2. Correlation of Bulk Dielectric and Piezoelectric Properties to the Local Scale Phase Transformations, Domain Morphology, and Crystal Structure Modified

    Energy Technology Data Exchange (ETDEWEB)

    Priya, Shashank [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Viehland, Dwight [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)

    2014-12-14

    Three year program entitled “Correlation of bulk dielectric and piezoelectric properties to the local scale phase transformations, domain morphology, and crystal structure in modified lead-free grain-textured ceramics and single crystals” was supported by the Department of Energy. This was a joint research program between D. Viehland and S. Priya at Virginia Tech. Single crystal and textured ceramics have been synthesized and characterized. Our goals have been (i) to conduct investigations of lead-free piezoelectric systems to establish the local structural and domain morphologies that result in enhanced properties, and (ii) to synthesize polycrystalline and grain oriented ceramics for understanding the role of composition, microstructure, and anisotropy

  3. Evaluation of the Structure and Acid-Base Properties of Bulk Wood by FT-Raman Spectroscopy.

    Science.gov (United States)

    Shen; Rahiala; Rosenholm

    1998-10-15

    The structure of pine wood (Pinus silvestris L.) has been analyzed by FT-Raman spectroscopy, taking birch wood and the wood components cellulose, hemicellulose (xylan), and lignin as well as previously characterized wood resins as references. The acid-base properties of bulk pine wood were evaluated by comparing the spectra recorded before and after the treatment with various solvents. After the treatment with the probe liquids having only a Lifshitz-van der Waals (LW) component, it was found that the LW interactions in pine wood take place without changing the main structure. After treatment with Lewis acid-base active probe liquids, the spectra indicate that, e.g., the intense peak located at approximately 2936 cm-1 (CH2 stretch) seems to disappear, suggesting that this peak may be related to Lewis acidity. In addition, after treatment with a Lewis acid, it was found that the intense peak located at approximately 1657 cm-1 (C&dbond;C) is shifted, relating to Lewis basicity. With the ratio approximately 2936/ approximately 1657 cm-1 as a measure of the acid-base properties of bulk wood, a value of about 2.00 indicates that the bulk pine wood is largely acidic. The pH determined supports the evaluation made by FT-Raman spectroscopy. Copyright 1998 Academic Press.

  4. Evaluation of the structure and acid-base properties of bulk wood by FT-Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Q.; Rahiala, H.; Rosenholm, J.B. [Aabo Akademi Univ, Turku (Finland). Dept. of Physical Chemistry

    1998-10-15

    The structure of pine wood (Pinus silvestris L.) has been analyzed by FT-Raman spectroscopy, taking birch wood and the wood components cellulose, hemicellulose (xylan), and lignin as well as previously characterized wood resins as references. The acid-base properties of bulk pine wood were evaluated by comparing the spectra recorded before and after the treatment with various solvents. After the treatment with the probe liquids having only a Lifshitz-van der Waals (LW) component, it was found that the LW interactions in pine wood take place without changing the main structure. After treatment with Lewis acid-base active probe liquids, the spectra indicate that, e.g., the intense peak located at {approximately}2936 cm{sup {minus}1} (CH{sub 2} stretch) seems to disappear, suggesting that this peak may be related to Lewis acidity. In addition, after treatment with a Lewis acid, it was found that the intense peak located at {approximately}1657 cm{sup {minus}1} (C{double_bond}C) is shifted, relating to Lewis basicity. With the ratio {approximately}2936/{approximately}1657 cm{sup {minus}1} as a measure of the acid-base properties of bulk wood, a value of about 2.00 indicates that the bulk pine wood is largely acidic. The pH determined supports the evaluation made by FT-Raman spectroscopy.

  5. The role of precursory structures on Tertiary deformation in the Black Forest—Hegau region

    Science.gov (United States)

    Egli, Daniel; Mosar, Jon; Ibele, Tobias; Madritsch, Herfried

    2017-10-01

    Structural inheritance of preexisting crustal discontinuities is widely accepted to have played a crucial role during the Cenozoic tectonic evolution of the northern Alpine foreland. It is recognised as a process that can strongly influence local fault kinematics and strain patterns. The case study presented herein is dedicated to the tectonic analysis of the Freiburg-Bonndorf-Bodensee Fault Zone (FBBFZ) located at the external margin of the northern Alpine Molasse Basin and extending into the crystalline Black Forest Massif. The structure and kinematics of this crustal-scale fault zone are investigated by means of a regional analysis of locally mapped faults, kinematic analysis of outcrop-scale fractures and slip vector modelling. The exceptional possibility of analysing the fault zone exposed from basement to cover allowed for an evaluation of interaction between precursory structures and subsequent deformation features. The results of this study show that the crystalline basement structures exposed along the FBBFZ had a strong imprint on the map-scale fault pattern observable in the Mesozoic and Tertiary sequences. Kinematic analysis of outcrop-scale fracture systems in the latter units yields evidence for local multi-directional extension and strike-slip faulting during Miocene to recent times. While these observations may evoke the interpretation of a multistage palaeostress history along the FBBFZ, slip vector modelling of a very well exposed FBBFZ segment suggests that the various strain records can alternatively be explained by one single regional stress tensor and be related to superordinate deep-seated strike-slip deformation.

  6. Structure and mechanical properties of a high-carbon steel subjected to severe deformation

    Science.gov (United States)

    Gorkunov, E. S.; Zadvorkin, S. M.; Goruleva, L. S.; Makarov, A. V.; Pecherkina, N. L.

    2017-10-01

    The structure and mechanical properties of a high-carbon eutectic steel subjected to the cold plastic deformation by hydrostatic extrusion in a wide range of true strain have been studied. Using scanning and transmission electron microscopy, it has been shown that the formation of cellular, fragmented, and submicrocrystalline structures occurs in the ferritic constituent of the pearlite structure of the steel upon extrusion. This is a consequence of the occurrence of dynamic recovery and continuous dynamic and post-dynamic recrystallization, which cause a decrease in the density of free dislocations at the true strain of more than 1.62. The partial dissolution of the carbide phase is also observed. It has been found that, at a true strain of up to 0.81, the strength properties of the investigated steel are determined mainly by subgrain, dislocation, and precipitation mechanisms of the strengthening; in the deformation range of 0.81-1.62, the role of the grainboundary strengthening increases. At strains above 1.62, grain-boundary strengthening is a prevailing mechanism in the formation of the level of strength properties of the extruded U8A steel. The ultimate tensile strength and yield stress over the entire strain range only uniquely correlate with the density of highangle boundaries; the dependences of the strength characteristics on other structural parameters are not monotonic.

  7. Kodaira-Spencer deformation of complex structures and Lagrangian field theory

    Science.gov (United States)

    Bandelloni, Giuseppe; Lazzarini, Serge

    1998-07-01

    Similar to the Beltrami parametrization of complex structures on a (compact) Riemann surface, we use in this paper the Kodaira-Spencer deformation theory of complex structures on a (compact) complex manifold of higher dimension. According to the Newlander-Nirenberg theorem, a smooth change of local complex coordinates is implemented with respect to an integrable complex structure parametrize by a Beltrami differential. The question of constructing a local field theory on a complex compact manifold is addressed and the action of smooth diffeomorphisms is studied in the BRS algebraic approach. The BRS cohomology for the diffeomorphisms gives generalized Gel'fand-Fuchs cocycles provided that the Kodaira-Spencer integrability condition is satisfied. The diffeomorphism anomaly is computed and turns out to be holomorphically split as in the bidimensional Lagrangian conformal models. Moreover, its algebraic structure is much more complicated than the one proposed in a recent paper [Losev et al. Nuc. Phys. B 484, 196 (1997)].

  8. CHANGE IN DEFORMATION PROPERTIES MODELING OF CONCRETE IN PROTECTIVE STRUCTURES OF NUCLEAR REACTOR BY IONIZING RADIATION

    Directory of Open Access Journals (Sweden)

    E. K. Agakhanov

    2016-01-01

    Full Text Available The necessity of studying the effect impact of elementary particles impact on the strength and deformation materials properties used in protective constructions nuclear reactors and reactor technology has been stipulated. A nuclear reactor pressure vessel from prestressed concrete, combining the functions of biological protection is to be considered. The neutron flux problem distribution in the pressure vessel of a nuclear reactor has been solved. The solution is made in axisymmetric with the finite element method using a flat triangular finite element. Computing has been conducted in Matlab package. The comparison with the results has been obtained using the finite difference method, as well as the graphs of changes under the influence of radiation exposure and the elastic modulus of concrete radiation deformations have been constructed. The proposed method allows to simulate changes in the deformation properties of concrete under the influence of neutron irradiation. Results of the study can be used in the calculation of stress-strain state of structures, taking into account indirect heterogeneity caused by the physical fields influence.

  9. Seismic deformation structures of the post-2300 a BP muddy sediments in Kawachi lowland plain, Osaka, Japan

    Science.gov (United States)

    Matsuda, J.-i.

    2000-09-01

    Deformed zones, consisting mainly of muddy sediments, deposited in palustrine environments, found during the excavations of archaeological sites, have been examined. The beds belong to the uppermost Holocene sequence, within 6 m depth from the present ground surface, in Kawachi alluvial lowland plain, Osaka Prefecture, Japan. Each deformation zone contained basically three deformation units related to fluidity and plasticity decreasing with depth beneath the fresh sedimentation surface. The units recognized were, from top to bottom: (1) a liquidized deformation unit expressed by a homogenized layer, in which the sediment and water have been mixed by turbulent flow; (2) a hydroplastic deformation unit characterized by a plumose pattern in the upper part of the unit and load structures in the lower part; and (3) a brittle deformation unit characterized by downward fissures and microfaults. The plumose pattern in the second unit may have formed where the more cohesive sediments in the lower part of the unit were dragged horizontally with repeated directional changes, and pulled upward by the movement of the sediments in the upper part. The load structures in the lower part of this unit are assumed to have been formed mainly by differential vertical and compressive forces applied to the sedimentary horizons. In the uppermost part of the liquidized deformation unit, load casts and pseudonodules with short horizontal tracks, suggesting movement while sinking, were seen locally. These features in the units are assumed to have been formed by the oscillatory and rotational force, irregular in intensity and direction, of an earthquake. The minor displacement of deformed sediments, such as mixing, truncation, intrusion, and injection, at the boundaries between the units and their internal layers suggests that the deformation process was initiated simultaneously in each unit, and was of short duration. The vertical occurrence order of the deformational features, similar to

  10. Palaeozoic oolitic ironstone of the French Armorican Massif: a chemical and structural trap for orogenic base metal-As-Sb-Au mineralisation during Hercynian strike-slip deformation

    Science.gov (United States)

    Gloaguen, Eric; Branquet, Yannick; Boulvais, Philippe; Moëlo, Yves; Chauvel, Jean-Jacques; Chiappero, Pierre-Jacques; Marcoux, Eric

    2007-04-01

    In the Saint-Aubin-des-Châteaux quarry (Armorican Hercynian belt, western France), an epigenetic hydrothermal alteration affects an oolitic ironstone layer intercalated within the Lower Ordovician Grès armoricain Formation. The hydrothermal overprint produced pervasive and massive sulphidation with stratoid pyritised lenticular bodies within the oolitic ironstone layer. These sulphide lenses are spatially associated with strike-slip faults and extend laterally from them. After the massive sulphidation stage (Fe-As, stage 1), subsequent fracturing allowed the deposition of base metals (stage 2) and Pb-Sb-Au (stage 3) parageneses in veins. The dominant brittle structures are vertical extension veins, conjugate shear veins and strike-slip faults of various orders. All these structures are filled with the same paragenetic sequence. Deformation analysis allows the identification of structures that developed incrementally via right-lateral simple shear compatible with bulk strain affecting the Central Armorican Domain. Each increment corresponds to a fracture set filled with specific parageneses. Successive hydrothermal pulses reflect clockwise rotation of the horizontal shortening direction. Geothermometry on chlorite and arsenopyrite shows an input of hot hydrothermal fluids (maximum of 390-350°C) during the main sulphide stage 1. The subsequent stages present a marked temperature drop (300-275°C). Lead isotopes suggest that the lead source is similar for all hydrothermal stages and corresponds to the underlying Neo-Proterozoic basement. Lead isotope data, relative ages of deformation and comparison with neighbouring deposits suggest that large-scale fluid pulses occurred during the whole Hercynian orogeny rather than pulses restricted to the late Hercynian period. The vicinity of the Hercynian internal domain appears as a key control for deformation and fluid flow in the oolitic ironstones, which acted as a chemical and structural trap for the hydrothermal fluids

  11. The prevalence of radiographic findings of structural hip deformities in female collegiate athletes.

    Science.gov (United States)

    Kapron, Ashley L; Peters, Christopher L; Aoki, Stephen K; Beckmann, James T; Erickson, Jill A; Anderson, Mike B; Pelt, Christopher E

    2015-06-01

    Structural deformities of the hip, including femoroacetabular impingement (FAI) and acetabular dysplasia, often limit athletic activity. Previous studies have reported an increased prevalence of radiographic cam FAI in male athletes, but data on the prevalence of structural hip deformities in female athletes are lacking. (1) To quantify the prevalence of radiographic FAI deformities and acetabular dysplasia in female collegiate athletes from 3 sports: volleyball, soccer, and track and field. (2) To identify possible relationships between radiographic measures of hip morphologic characteristics and physical examination findings. Cross-sectional study; Level of evidence, 3. Anteroposterior (AP) pelvis and frog-leg lateral radiographs were obtained from 63 female athletes participating in Division I collegiate volleyball, soccer, and track and field. Lateral center edge angle (LCEA) and acetabular index were measured on AP films. Alpha angle and head-neck offset were measured on frog-leg lateral films. Pain during the supine impingement examination and hip rotation at 90° of flexion were recorded. Random-effects linear regression was used for group comparisons and correlation analyses to account for the lack of independence of observations made on left and right hips. Radiographic cam deformity (alpha angle >50° and/or head-neck offset 40°) was noted in only 1% (1/126) of hips. No hips had radiographic mixed FAI (at least 1 of the 2 cam criteria and LCEA >40°). Twenty-one percent (26/126) of hips had an LCEA angles (48.2° ± 7.1°) compared with the soccer players (40.0° ± 6.8°; P .914) or the prevalence of dysplasia (LCEA .551). There were no significant correlations between the radiographic measures and internal rotation (all P > .077). There were no significant differences (all P > .089) in radiographic measures between hips that were painful (n = 26) during the impingement examination and those that were not. These female athletes had a lower prevalence of

  12. Structural transformations of mechanically induced top-down approach BaFe{sub 12}O{sub 19} nanoparticles synthesized from high crystallinity bulk materials

    Energy Technology Data Exchange (ETDEWEB)

    Low, Zhi Huang [Institute of Advanced Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan (Malaysia); Chen, Soo Kien [Institute of Advanced Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan (Malaysia); Department of Physics, Faculty of Science, University Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan (Malaysia); Ismail, Ismayadi, E-mail: kayzen@gmail.com [Institute of Advanced Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan (Malaysia); Tan, Kim Song [Advanced Imaging Centre, Malaysian Rubber Board, RRIM Sungai Buloh, 47000 Selangor (Malaysia); Liew, J.Y.C. [Department of Physics, Faculty of Science, University Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan (Malaysia)

    2017-05-01

    In this work, a top-down approach was applied to high crystallinity BaFe{sub 12}O{sub 19} bulks, breaking them into smaller nanoparticles by mechanochemical route. The effects of milling time, reaction mechanisms and structural information were investigated. Interestingly, three distinct stages of the mechanochemical mechanism were observed. The XRD results indicated that the BaFe{sub 12}O{sub 19} phase existed even though the mechanical energy had induced the formation of an amorphous phase in the material. The average crystallite size decreased during the first stage and the intermediate stage, and increased during the final stage of the mechanical alloying. A Rietveld refinement analysis suggested the deformation of a mechanically-triggered polyhedral in the magnetoplumbite structure. FESEM micrographs indicated that fragmentation predominated during the first and intermediate stages, until a steady equilibrium state was achieved at in the final stage, where a narrow particle size distribution was observed. HRTEM micrographs suggested the formation of a non-uniform nanostructure shell surrounding the ordered core materials at the edge-interface region. The thickness of the amorphous surface layer extended up to 12 nm during the first and intermediate stages, and diminished to approximately 3 nm after 20 h milling. VSM results showed a mixture of ferromagnetic, superparamagnetic, and paramagnetic behaviours. However, different magnetic behaviours predominated at different milling time, which strongly related to the defects, distorted polyhedra, and non-equilibrium amorphous layers of the material. - Highlights: • Nanoparticles of BaFe{sub 12}O{sub 19} are successfully prepared. • Morphological and structural properties rely on mechanochemical mechanism. • Three stages of mechanochemical mechanism was observed. • Core shell structures (3–12 nm) was found during by extending the milling time. • Magnetic properties were strongly related with the

  13. 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.

  14. Structure of deformed silicon and implications for low cost solar cells

    Science.gov (United States)

    Mardesich, N.; Leipold, M. H.; Turner, G. B.; Digges, T. G., Jr.

    1978-01-01

    The microstructure and minority carrier lifetime of silicon were investigated in uniaxially compressed silicon samples. The objective of the investigation was to determine if it is feasible to produce silicon solar cells from sheet formed by high temperature rolling. The initial structure of the silicon samples ranged from single crystal to fine-grained polycrystals. The samples had been deformed at strain rates of 0.1 to 8.5/sec and temperatures of 1270-1380 C with subsequent annealing at 1270-1380 C. The results suggest that high temperature rolling of silicon to produce sheet for cells of high efficiency is not practical.

  15. Effect of Ca substitution on some physical properties of nano-structured and bulk Ni-ferrite samples

    Energy Technology Data Exchange (ETDEWEB)

    Assar, S.T., E-mail: soha_talaat@yahoo.com; Abosheiasha, H.F.

    2015-01-15

    Nanoparticles of Ni{sub 1−x}Ca{sub x}Fe{sub 2}O{sub 4} (x=0.0, 0.02, 0.04, 0.06 and 0.10) were prepared by citrate precursor method. A part of these samples was sintered at 600 °C for 2 h in order to keep the particles within the nano-size while the other part was sintered at 1000 °C to let the particles to grow to the bulk size. The effect of Ca{sup 2+} ion substitution in nickel ferrite on some structural, magnetic, electrical and thermal properties was investigated. All samples were characterized by using X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM). A two probe method was used to measure the dc electrical conductivity whereas the photoacoustic (PA) technique was used to determine the thermal diffusivity of the samples. To interpret different experimental results for nano and bulk samples some cation distributions were assumed based on the VSM and XRD data. These suggested cation distributions give logical explanations for other experimental results such as the observed values of the absorption bands in FTIR spectra and the dc conductivity results. Finally, in the thermal measurements it was found that increasing the Ca{sup 2+} ion content causes a decrease in the thermal diffusivity of both nano and bulk samples. The explanation of this behavior is ascribed to the phonon-phonon scattering. - Highlights: • The physical properties of both nano and bulk samples of Ni-Ca ferrites were investigated. • Cation distribution plays a vital role in tailoring the physical properties of all the samples. • The dc conductivity of the nanosamples is higher than their bulk counterparts. • Increasing Ca{sup 2+} content enhances M{sub s}, M{sub r}, and σ{sub dc} of the bulk samples over their nanocounterparts. • The behavior of thermal diffusivity of the samples attributed to the phonon-phonon scattering.

  16. 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.

  17. Low temperature dynamics of surface and bulk electronic structure of quantum dots

    Science.gov (United States)

    Krishnamurthy Grandhi, G.; Tomar, Renu; Viswanatha, Ranjani

    2017-09-01

    Absolute energies of band edges have proven to be very important for various applications like hydrogen generation, solar water splitting and solar cell optimization. Energy differences as small as 50-100 meV have been shown to largely affect device efficiencies. Device operational temperature can vary largely and temperature dependence of band gap is well known in bulk semiconductor literature. However, there are only a few studies on variation of band gap in quantum dots and none of them characterize the relative energy variation of band edges in spite of their importance in various applications. This is mainly due to the absence of an internal standard that can be used to study the variation of band edges. Here, in this paper, we introduce a technique wherein we utilize Cu dopant emission as an internal probe. Using this technique, we report the variation of band gap, conduction band and valence band edges of CdS and CdSe quantum dots as a function of temperature and size. We found that band gap variation is similar to that of bulk but with a higher average phonon energy. The band edge variation is characterized by a dominant conduction band shift for larger sizes with decreasing temperature while the smaller size QDs show the variation in both conduction band and valence band. Further, we have also utilized this method to study the binding energy of the trap states as a function of temperature using Cu photoluminescence quantum yield and average lifetime of Cu photoluminescence.

  18. Atomic simulations of twist grain boundary structures and deformation behaviors in aluminum

    Directory of Open Access Journals (Sweden)

    Qing Yin

    2017-01-01

    Full Text Available The structures and behaviors of grain boundaries (GBs have profound effects on the mechanical properties of polycrystalline materials. In this paper, twist GBs in aluminum were investigated with molecular dynamic simulations to reveal their atomic structures, energy and interactions with dislocations. One hundred twenty-six twist GBs were studied, and the energy of all these twist GBs were calculated. The result indicates that and twist GBs have lower energy than twist GBs because of their higher interplanar spacing. In addition, 12 types of twist GBs in aluminum were chosen to explore the deformation behaviors. Low angle twist GBs with high density of network structures can resist greater tension because mutually hindering behaviors between partial dislocations increase the twist GB strength.

  19. PSP SAR interferometry monitoring of ground and structure deformations applied to archaeological sites

    Science.gov (United States)

    Costantini, Mario; Francioni, Elena; Trillo, Francesco; Minati, Federico; Margottini, Claudio; Spizzichino, Daniele; Trigila, Alessandro; Iadanza, Carla

    2017-04-01

    Archaeological sites and cultural heritage are considered as critical assets for the society, representing not only the history of region or a culture, but also contributing to create a common identity of people living in a certain region. In this view, it is becoming more and more urgent to preserve them from climate changes effect and in general from their degradation. These structures are usually just as precious as fragile: remote sensing technology can be useful to monitor these treasures. In this work, we will focus on ground deformation measurements obtained by satellite SAR interferometry and on the methodology adopted and implemented in order to use the results operatively for conservation policies in a Italian archaeological site. The analysis 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 technology characterized by the fact of exploiting in the processing only the relative properties between close points (pairs) in order to overcome atmospheric artefacts (which are one of the main problems of SAR interferometry). Validations analyses [Costantini et al. 2015] settled 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. Considering the limitations of all the interferometric techniques, in particular the fact that the measurement are along the line of sight (LOS) and the geometric distortions, in order to obtain the maximum information from interferometric analysis, both ascending and descending geometry have been used. The ascending analysis allows selecting measurements points over the top and, approximately, South-West part of the structures, while the descending one over the top and the South-East part of the structures. The interferometric techniques needs

  20. Honey Bee Deformed Wing Virus Structures Reveal that Conformational Changes Accompany Genome Release.

    Science.gov (United States)

    Organtini, Lindsey J; Shingler, Kristin L; Ashley, Robert E; Capaldi, Elizabeth A; Durrani, Kulsoom; Dryden, Kelly A; Makhov, Alexander M; Conway, James F; Pizzorno, Marie C; Hafenstein, Susan

    2017-01-15

    The picornavirus-like deformed wing virus (DWV) has been directly linked to colony collapse; however, little is known about the mechanisms of host attachment or entry for DWV or its molecular and structural details. Here we report the three-dimensional (3-D) structures of DWV capsids isolated from infected honey bees, including the immature procapsid, the genome-filled virion, the putative entry intermediate (A-particle), and the empty capsid that remains after genome release. The capsids are decorated by large spikes around the 5-fold vertices. The 5-fold spikes had an open flower-like conformation for the procapsid and genome-filled capsids, whereas the putative A-particle and empty capsids that had released the genome had a closed tube-like spike conformation. Between the two conformations, the spikes undergo a significant hinge-like movement that we predicted using a Robetta model of the structure comprising the spike. We conclude that the spike structures likely serve a function during host entry, changing conformation to release the genome, and that the genome may escape from a 5-fold vertex to initiate infection. Finally, the structures illustrate that, similarly to picornaviruses, DWV forms alternate particle conformations implicated in assembly, host attachment, and RNA release. Honey bees are critical for global agriculture, but dramatic losses of entire hives have been reported in numerous countries since 2006. Deformed wing virus (DWV) and infestation with the ectoparasitic mite Varroa destructor have been linked to colony collapse disorder. DWV was purified from infected adult worker bees to pursue biochemical and structural studies that allowed the first glimpse into the conformational changes that may be required during transmission and genome release for DWV. Copyright © 2017 American Society for Microbiology.

  1. 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.

  2. Crustal Structure and Deformation of the Yakutat Microplate: New Insights From STEEP Marine Seismic Reflection Data

    Science.gov (United States)

    Lowe, L. A.; Gulick, S. P.; Christeson, G.; van Avendonk, H.; Reece, R.; Elmore, R.; Pavlis, T.

    2008-12-01

    In fall 2008, we will conduct an active source marine seismic experiment of the offshore Yakutat microplate in the northern Gulf of Alaska. The survey will be conducted aboard the academic research vessel, R/V Marcus Langseth, collecting deep-penetrating multi-channel seismic reflection survey using an 8-km, 640 channel hydrophone streamer and a 6600 cu. in., 36 airgun array. The survey is the concluding data acquisition phase for the ST. Elias Erosion and tectonics Project (STEEP), a multi-institution NSF-Continental Dynamics project investigating the interplay of climate and tectonics in the Chugach-St. Elias Mountains in southern Alaska. The experiment will also provide important site survey information for possible future Integrated Ocean Drilling Program investigations. Two profiles coincident with wide-angle refraction data (see Christeson, et al., this session) will image structural changes across the Dangerous River Zone from east to west and the Transition Fault from south to north. We will also image the western portion of the Transition Fault to determine the nature of faulting along this boundary including whether or not the Pacific Plate is underthrusting beneath the Yakutat microplate as part of this collision. Our westernmost profile will image the Kayak Island Zone, typically described as the northern extension of the Aleutian megathrust but which may be a forming suture acting as a deformation backstop for the converging Yakutat and North American plates. Profiles across the Pamplona Zone, the current Yakutat-North America deformation front, will further constrain relative timing of structural development and the depth of deformation on the broad folds and thrust faults that comprise the area. This new dataset will allow further insight into regional tectonics of the St. Elias region as well as provide more detail regarding the development of the south Alaskan margin during major Plio-Pleistocene glacial- interglacial periods.

  3. Minimizing structural deformation of gold nanorods in plasmon-enhanced dye-sensitized solar cells

    Science.gov (United States)

    Törngren, Björn; Sandén, Simon; Nyman, Johan O.; Tiihonen, Armi; Jiang, Hua; Ruokolainen, Janne; Halme, Janne; Österbacka, Ronald; Smått, Jan-Henrik

    2017-11-01

    Plasmonic metal nanoparticles have shown great promise in enhancing the light absorption of organic dyes and thus improving the performance of dye-sensitized solar cells (DSSCs). However, as the plasmon resonance of spherical nanoparticles is limited to a single wavelength maximum (e.g., 520 nm for Au nanoparticles), we have here utilized silica-coated gold nanorods (Au@SiO2 NRs) to improve the performance at higher wavelengths as well. By adjusting the aspect ratio of the Au@SiO2 NRs, we can shift their absorption maxima to better match the absorption spectrum of the utilized dye (here we targeted the 600-800 nm range). The main challenge in utilizing anisotropic nanoparticles in DSSCs is their deformation during the heating step required to sinter the mesoporous TiO2 photoanode and we show that the Au@SiO2 NRs start to deform already at temperatures as low as 200 °C. In order to circumvent this problem, we incorporated the Au@SiO2 NRs in a TiO2 nanoparticle suspension that does not need high sintering temperatures to produce a functional photoanode. With various characterization methods, we observed that adding the plasmonic particles also affected the structure of the produced films. Nonetheless, utilizing this low-temperature processing protocol, we were able to minimize the structural deformation of the gold nanorods and preserve their characteristic plasmon peaks. This allowed us to see a clear redshift of the maximum in the incident photon-to-current efficiency spectra of the plasmonic devices (Δλ 14 nm), which further proves the great potential of utilizing Au@SiO2 NRs in DSSCs. [Figure not available: see fulltext.

  4. Effect of Severe Plastic Deformation on Structure and Properties of Al-Sc-Ta and Al-Sc-Ti Alloys.

    Science.gov (United States)

    Berezina, Alla; Monastyrska, Tetiana; Davydenko, Olexandr; Molebny, Oleh; Polishchuk, Sergey

    2017-12-01

    The comparative analysis of the effect of monotonous and non-monotonous severe plastic deformations (SPD) on the structure and properties of aluminum alloys has been carried out. Conventional hydrostatic extrusion (HE) with a constant deformation direction and equal-channel angular hydroextrusion (ECAH) with an abrupt change in the deformation direction were chosen for the cases of monotonous and non-monotonous SPD, respectively. Model cast hypoeutectic Al-0.3%Sc alloys and hypereutectic Al-0.6%Sc alloys with Ta and Ti additives were chosen for studying. It was demonstrated that SPD of the alloys resulted in the segregation of the material into active and inactive zones which formed a banded structure. The active zones were shown to be bands of localized plastic deformation. The distance between zones was found to be independent of the accumulated strain degree and was in the range of 0.6-1 μm. Dynamic recrystallization in the active zones was observed using TEM. The dynamic recrystallization was accompanied by the formation of disclinations, deformation bands, low-angle, and high-angle boundaries, i.e., rotational deformation modes developed. The dynamic recrystallization was more intense during the non-monotonous deformation as compared with the monotonous one, which was confirmed by the reduction of texture degree in the materials after ECAH.

  5. Lie superbialgebra structures on the Lie superalgebra (C3+A) and deformation of related integrable Hamiltonian systems

    Science.gov (United States)

    Eghbali, A.; Rezaei-Aghdam, A.

    2017-06-01

    Admissible structure constants related to the dual Lie superalgebras of particular Lie superalgebra (C3+A ) are found by straightforward calculations from the matrix form of super Jacobi and mixed super Jacobi identities which are obtained from adjoint representation. Then, by making use of the automorphism supergroup of the Lie superalgebra (C3+A ) , the Lie superbialgebra structures on the Lie superalgebra (C3+A ) are obtained and classified into inequivalent 31 families. We also determine all corresponding coboundary and bi-r-matrix Lie superbialgebras. The quantum deformations associated with some Lie superbialgebras (C3+A ) are obtained, together with the corresponding deformed Casimir elements. As an application of these quantum deformations, we construct a deformed integrable Hamiltonian system from the representation of the Hopf superalgebra Uλ (Cp=1 2 ,𝜖⊕A1 ,1 )(C3+A).

  6. Tracking molecular structure deformation of nitrobenzene and its torsion-vibration coupling by intense pumping CARS

    Science.gov (United States)

    Wang, Chang; Wu, Hong-Lin; Song, Yun-Fei; He, Xing; Yang, Yan-Qiang; Tan, Duo-Wang

    2016-11-01

    The structural deformation induced by intense laser field of liquid nitrobenzene (NB) molecule, a typical molecule with restricting internal rotation, is tracked by time- and frequency-resolved coherent anti-Stokes. Raman spectroscopy (CARS) technique with an intense pump laser. The CARS spectra of liquid NB show that the NO2 torsional mode couples with the NO2 symmetric stretching mode, and the NB molecule undergoes ultrafast structural deformation with a relaxation time of 265 fs. The frequency of NO2 torsional mode in liquid NB (42 cm-1) at room temperature is found from the sum and difference combination bands involving the NO2 symmetric stretching mode and torsional mode in time- and frequency-resolved CARS spectra. Project supported by the National Natural Science Foundation of China (Grant Nos. 21173063 and 21203047), the Foundation of Heilongjiang Bayi Agricultural University, China (Grant No. XZR2014-16), NSAF (Grant No. U1330106), and the Special Research Project of National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics (Grant No. 2012-S-07).

  7. Assessment of digital image correlation as a method of obtaining deformations of a structure under fluid load

    OpenAIRE

    Banks, Joseph; Marimon Giovannetti, Laura; Soubeyran, Xavier; Wright, Alexander; Turnock, Stephen; Boyd, Stephen

    2015-01-01

    Digital Image Correlation (DIC) is employed for the measurement of full-field deformation during fluid-structure interaction experiments in a wind tunnel. The methodology developed for the wind tunnel environment is quantitatively assessed. The static deformation error of the system is shown to be less than 0.8% when applied to a curved aerofoil specimen moved through known displacements using a micrometer. Enclosed camera fairings were shown to be required to minimise error due to wind induc...

  8. 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.

  9. Segmentation of the pectoral muscle in breast MR images using structure tensor and deformable model

    Science.gov (United States)

    Lee, Myungeun; Kim, Jong Hyo

    2012-02-01

    Recently, breast MR images have been used in wider clinical area including diagnosis, treatment planning, and treatment response evaluation, which requests quantitative analysis and breast tissue segmentation. Although several methods have been proposed for segmenting MR images, segmenting out breast tissues robustly from surrounding structures in a wide range of anatomical diversity still remains challenging. Therefore, in this paper, we propose a practical and general-purpose approach for segmenting the pectoral muscle boundary based on the structure tensor and deformable model. The segmentation work flow comprises four key steps: preprocessing, detection of the region of interest (ROI) within the breast region, segmenting the pectoral muscle and finally extracting and refining the pectoral muscle boundary. From experimental results we show that the proposed method can segment the pectoral muscle robustly in diverse patient cases. In addition, the proposed method will allow the application of the quantification research for various breast images.

  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. Characteristic structures and properties of nanostructured metals prepared by plastic deformation

    DEFF Research Database (Denmark)

    Huang, Xiaoxu

    2011-01-01

    This chapter focuses on describing the characteristic microstructures of nanostructured metals produced by plastic deformation to ultrahigh strains and their correlation with hardening by annealing and softening by deformation. The results suggest that optimising microstructure and the mechanical...

  12. Structural, compositional and magnetic characterization of bulk V{sub 2}O{sub 5} doped ZnO system

    Energy Technology Data Exchange (ETDEWEB)

    Karamat, S. [Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 637616 (Singapore); Rawat, R.S., E-mail: rajdeep.rawat@nie.edu.sg [Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 637616 (Singapore); Lee, P.; Tan, T.L. [Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, 637616 (Singapore); Ramanujan, R.V. [School of Material Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Zhou, W. [Precision Engineering and Nanotechnology Centre, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2010-02-01

    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 Zn{sup 2+} ions by vanadium ions in ZnO lattice. Raman spectroscopy reveals the change in ZnO modes positions due to vanadium doping. The appearance of E{sub 1} and E{sub 2} 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 V{sup 2+} 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.

  13. 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.

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

    Science.gov (United States)

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

    2008-01-01

    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. PMID:18307769

  15. Deformation and fracture behavior of composite structured Ti-Nb-Al-Co(-Ni) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Okulov, I. V., E-mail: i.okulov@ifw-dresden.de; Marr, T.; Schultz, L.; Eckert, J. [IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Institut für Werkstoffwissenschaft, Technische Universität Dresden, D-01062 Dresden (Germany); Kühn, U. [IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Freudenberger, J. [IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Institut für Werkstoffwissenschaft, Technische Universität Bergakademie Freiberg, Gustav-Zeuner-Str. 5, D-09599 Freiberg (Germany); Oertel, C.-G.; Skrotzki, W. [Institut für Strukturphysik, Technische Universität Dresden, D-01062 Dresden (Germany)

    2014-02-17

    Tensile ductility of the Ti-based composites, which consist of a β-Ti phase surrounded by ultrafine structured intermetallics, is tunable through the control of intermetallics. The two Ti-based alloys studied exhibit similar compressive yield strength (about 1000 MPa) and strain (about 35%–40%) but show a distinct difference in their tensile plasticity. The alloy Ti{sub 71.8}Nb{sub 14.1}Ni{sub 7.4}Al{sub 6.7} fractures at the yield stress while the alloy Ti{sub 71.8}Nb{sub 14.1}Co{sub 7.4}Al{sub 6.7} exhibits about 4.5% of tensile plastic deformation. To clarify the effect of microstructure on the deformation behavior of these alloys, tensile tests were carried out in the scanning electron microscope. It is shown that the distribution as well as the type of intermetallics affects the tensile ductility of the alloys.

  16. A fixed-mesh method for incompressible flow structure systems with finite solid deformations

    Science.gov (United States)

    Zhao, Hong; Freund, Jonathan B.; Moser, Robert D.

    2008-03-01

    A fixed-mesh algorithm is proposed for simulating flow-structure interactions such as those occurring in biological systems, in which both the fluid and solid are incompressible and the solid deformations are large. Several of the well-known difficulties in simulating such flow-structure interactions are avoided by formulating a single set of equations of motion on a fixed Eulerian mesh. The solid's deformation is tracked to compute elastic stresses by an overlapping Lagrangian mesh. In this way, the flow-structure interaction is formulated as a distributed body force and singular surface force acting on an otherwise purely fluid system. These forces, which depend on the solid elastic stress distribution, are computed on the Lagrangian mesh by a standard finite-element method and then transferred to the fixed Eulerian mesh, where the joint momentum and continuity equations are solved by a finite-difference method. The constitutive model for the solid can be quite general. For the force transfer, standard immersed-boundary and immersed-interface methods can be used and are demonstrated. We have also developed and demonstrated a new projection method that unifies the transfer of the surface and body forces in a way that exactly conserves momentum; the interface is still effectively sharp for this approach. The spatial convergence of the method is observed to be between first- and second-order, as in most immersed-boundary methods for membrane flows. The algorithm is demonstrated by the simulations of an advected elastic disk, a flexible leaflet in an oscillating flow, and a model of a swimming jellyfish.

  17. Simulation Study of Stress and Deformation Behaviour of Debonded Laminated Structure

    Science.gov (United States)

    Hirwani, C. K.; Mittal, H.; Panda, S. K.; Mahapatra, S. S.; Mandal, S. K.; De, A. K.

    2017-02-01

    The bending strength and deformation characteristics of the debonded laminated plate under the uniformly distributed loading (UDL) have been investigated in this research article. For the simulation study, an internally damaged laminated plate structure model has been developed in ANSYS based on the first-order shear deformable kinematic theory via ANSYS parametric design language (APDL) code. The internal debonding within the laminated structure is incorporated using two sub-laminate approach. Further, the convergence (different mesh densities), as well as the validity (comparing the responses with published results) of the present simulation model, have been performed by solving the deflection responses under the influence of transversely loaded layered structure. Also, to show the coherence of the simulation analysis the results are compared with the experimental bending results of the homemade Glass/Epoxy composite with artificial delamination. For the experimental analysis, Glass/Epoxy laminated composite seeded with delamination at the central mid-plane of the laminate is fabricated using an open mould hand lay-up composites fabrication technique. For the computational purpose, the necessary material properties of fabricated composite plate evaluated experimentally via uniaxial tensile test (Universal Testing Machine INSTRON-1195). Further, the bending (three-point bend test) test is conducted with the help of Universal Testing Machine INSTRON-5967. Finally, the effect different geometrical and material parameters (thickness ratio, modular ratio, constraint conditions) and magnitude of the loading on the static deflection and stress behaviour of the delaminated composite plate are investigated thoroughly by solving different kinds of numerical illustrations and discussed in detail.

  18. Three-dimensional printing and deformation behavior of low-density target structures by two-photon polymerization

    Science.gov (United States)

    Liu, Ying; Stein, Ori; Campbell, John H.; Jiang, Lijia; Petta, Nicole; Lu, Yongfeng

    2017-08-01

    Two-photon polymerization (2PP), a 3D nano to microscale additive manufacturing process, is being used for the first time to fabricate small custom experimental packages ("targets") to support laser-driven high-energy-density (HED) physics research. Of particular interest is the use of 2PP to deterministically print low-density, low atomic-number (CHO) polymer matrices ("foams") at millimeter scale with sub-micrometer resolution. Deformation during development and drying of the foam structures remains a challenge when using certain commercial photo-resins; here we compare use of acrylic resins IP-S and IP-Dip. The mechanical strength of polymeric beam and foam structures is examined particularly the degree of deformation that occurs during the development and drying processes. The magnitude of the shrinkage in the two resins in quantified by printing sample structures and by use of FEA to simulate the deformation. Capillary drying forces are shown to be small and likely below the elastic limit of the core foam structure. In contrast the substantial shrinkage in IP-Dip ( 5-10%) cause large shear stresses and associated plastic deformation particularly near constrained boundaries such as the substrate and locations with sharp density variation. The inherent weakness of stitching boundaries is also evident and in certain cases can lead to delamination. Use of IP-S shows marked reduction in deformation with a minor loss of print resolution

  19. Analysis of mitochondrial 3D-deformation in cardiomyocytes during active contraction reveals passive structural anisotropy of orthogonal short axes.

    Directory of Open Access Journals (Sweden)

    Yael Yaniv

    Full Text Available The cardiomyocyte cytoskeleton, composed of rigid and elastic elements, maintains the isolated cell in an elongated cylindrical shape with an elliptical cross-section, even during contraction-relaxation cycles. Cardiomyocyte mitochondria are micron-sized, fluid-filled passive spheres distributed throughout the cell in a crystal-like lattice, arranged in pairs sandwiched between the sarcomere contractile machinery, both longitudinally and radially. Their shape represents the extant 3-dimensional (3D force-balance. We developed a novel method to examine mitochondrial 3D-deformation in response to contraction and relaxation to understand how dynamic forces are balanced inside cardiomyocytes. The variation in transmitted light intensity induced by the periodic lattice of myofilaments alternating with mitochondrial rows can be analyzed by Fourier transformation along a given cardiomyocyte axis to measure mitochondrial deformation along that axis. This technique enables precise detection of changes in dimension of ∼1% in ∼1 µm (long-axis structures with 8 ms time-resolution. During active contraction (1 Hz stimulation, mitochondria deform along the length- and width-axes of the cell with similar deformation kinetics in both sarcomere and mitochondrial structures. However, significant deformation anisotropy (without hysteresis was observed between the orthogonal short-axes (i.e., width and depth of mitochondria during electrical stimulation. The same degree of deformation anisotropy was also found between the myocyte orthogonal short-axes during electrical stimulation. Therefore, the deformation of the mitochondria reflects the overall deformation of the cell, and the apparent stiffness and stress/strain characteristics of the cytoskeleton differ appreciably between the two cardiomyocyte orthogonal short-axes. This method may be applied to obtaining a better understanding of the dynamic force-balance inside cardiomyocytes and of changes in the

  20. Criterion for surface contact deformation of metals

    NARCIS (Netherlands)

    Jamari, Jamari; Schipper, Dirk J.

    2007-01-01

    In most engineering applications, bulk plastic deformation of the surface is avoided. There is, however, no criterion for determining whether or not bulk plastic deformation occurs during the contact between rough surfaces. This paper presents a criterion for predicting the deformation behaviour of

  1. Study of Structure and Deformation Pathways in Ti-7Al Using Atomistic Simulations, Experiments, and Characterization

    Science.gov (United States)

    Venkataraman, Ajey; Shade, Paul A.; Adebisi, R.; Sathish, S.; Pilchak, Adam L.; Viswanathan, G. Babu; Brandes, Matt C.; Mills, Michael J.; Sangid, Michael D.

    2017-05-01

    Ti-7Al is a good model material for mimicking the α phase response of near- α and α+ β phases of many widely used titanium-based engineering alloys, including Ti-6Al-4V. In this study, three model structures of Ti-7Al are investigated using atomistic simulations by varying the Ti and Al atom positions within the crystalline lattice. These atomic arrangements are based on transmission electron microscopy observations of short-range order. The elastic constants of the three model structures considered are calculated using molecular dynamics simulations. Resonant ultrasound spectroscopy experiments are conducted to obtain the elastic constants at room temperature and a good agreement is found between the simulation and experimental results, providing confidence that the model structures are reasonable. Additionally, energy barriers for crystalline slip are established for these structures by means of calculating the γ-surfaces for different slip systems. Finally, the positions of Al atoms in regards to solid solution strengthening are studied using density functional theory simulations, which demonstrate a higher energy barrier for slip when the Al solute atom is closer to (or at) the fault plane. These results provide quantitative insights into the deformation mechanisms of this alloy.

  2. Modeling internal deformation of salt structures targeted for radioactive waste disposal

    Energy Technology Data Exchange (ETDEWEB)

    Chemia, Zurab

    2008-09-15

    This thesis uses results of systematic numerical models to argue that externally inactive salt structures, which are potential targets for radioactive waste disposal, might be internally active due to the presence of dense layers or blocks within a salt layer. The three papers that support this thesis use the Gorleben salt diapir (NW Germany), which was targeted as a future final repository for high-grade radioactive waste, as a general guideline. The first two papers present systematic studies of the parameters that control the development of a salt diapir and how it entrains a dense anhydrite layer. Results from these numerical models show that the entrainment of a dense anhydrite layer within a salt diapir depends on four parameters: sedimentation rate, viscosity of salt, perturbation width and the stratigraphic location of the dense layer. The combined effect of these four parameters, which has a direct impact on the rate of salt supply (volume/area of the salt that is supplied to the diapir with time), shape a diapir and the mode of entrainment. Salt diapirs down-built with sedimentary units of high viscosity can potentially grow with an embedded anhydrite layer and deplete their source layer (salt supply ceases). However, when salt supply decreases dramatically or ceases entirely, the entrained anhydrite layer/segments start to sink within the diapir. In inactive diapirs, sinking of the entrained anhydrite layer is inevitable and strongly depends on the rheology of the salt, which is in direct contact with the anhydrite layer. During the post-depositional stage, if the effective viscosity of salt falls below the threshold value of around 1018-1019 Pa s, the mobility of anhydrite blocks might influence any repository within the diapir. However, the internal deformation of the salt diapir by the descending blocks decreases with increase in effective viscosity of salt. The results presented in this thesis suggest that it is highly likely that salt structures

  3. Modeling of bulk acoustic wave devices built on piezoelectric stack structures: impedance matrix analysis and network representation.

    Science.gov (United States)

    Zhang, Victor Y; Dubus, Bertrand; Lefebvre, Jean Etienne; Gryba, Tadeusz

    2008-03-01

    The fundamental electro-acoustic properties of a solid layer are deduced in terms of its impedance matrix (Z) and represented by a network for modeling the bulk acoustic wave devices built on piezoelectric stacked structures. A piezoelectric layer is described by a three-port equivalent network, a nonpiezoelectric layer, and a short- or open-circuit piezoelectric layer by a two-port one. Electrical input impedance of the resonator is derived in terms of the Z-matrix of both the piezoelectric layer and an external load, the unique expression applies whether the resonator is a mono- or electroded-layer or a solidly mounted resonator (SMR). The loading effects of Al-electrodes on the resonating frequencies of the piezoelectric ZnO-layer are analyzed. Transmission and reflection properties of Bragg mirrors are investigated along with the bulk radiation in SMR. As a synthesizing example, a coupled resonator filter (CRF) is analyzed using the associated two-port equivalent network and by calculating the power transmission to a 50Omega-load. The stacked crystal filter is naturally included in the model as a special case of CRF. Combining a comprehensive matrix analysis and an instructive network representation and setting the problem with a full vectorial formalism are peculiar features of the presented approach.

  4. 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.

  5. Seismically-generated hydroplastic deformation structures in the Late Miocene lacustrine deposits of the Malatya Basin, eastern Turkey

    Science.gov (United States)

    Koç Taşgın, Calibe

    2011-04-01

    The Late Miocene succession of continental deposits in the Malatya Basin, eastern Anatolia, comprises alluvial-fan, lacustrine and fluvial facies associations. This fault-bounded basin formed in a tectonically active region, notorious for strong earthquakes still today. The lacustrine deposits in the northern part of the basin show several isolated horizons of soft-sediment deformation, including such structures as slump folds, load and flame features, sand dikes and small-scale synsedimentary reverse faults with associated folds. There is no direct evidence supporting instabilities due to unequal loading or overloading, wave-induced cyclical and/or impulsive stresses, sudden changes in groundwater level or bioturbation capable of producing these deformation structures. The soft-sediment deformation structures described in the lacustrine deposits are interpreted as having developed as a result of seismic activity taking place along the Malatya fault zone, based on the tectonic setting of the basin, the lateral extent of the soft-sediment deformation structures over hundreds of metres, their confinement by undeformed layers, the presence of complex structures, and similarities with structures interpreted as being seismically induced in other areas and those obtained experimentally.

  6. Structure of Grain Boundaries and Aspects of Deformation Behavior in Nickel-Aluminum Alloys.

    Science.gov (United States)

    Kerans, Ronald James

    The structures of two grain boundaries in Ni _3Al were determined using transmission electron microscopy (TEM). The line directions and spacings of secondary grain boundary dislocations (gbds) were calculated for coincidence site lattice (CSL) relationships near the experimentally determined misorientations. The structures of the boundaries were found to be in good agreement with Sigma 9 and Sigma 31b relationships of the ordered lattice. The grain boundary dislocations were found to be characteristic of the ordered structure. No grouping of partial gbds was observed. Lattice dislocations consisting of pairs of 1/3 (112) superpartials bounding extended superlattice intrinsic stacking faults (SISFs) were observed by TEM. They were found to independently react to APB coupled 1/2 (110) pairs in the commonly observed pure screw orientation. Implications with regard to Kear-Wilsdorf type locking mechanisms and deformation behavior are discussed. Boron was observed to have strong effects upon the population of boundary types, grain size, and grain growth. In addition, small amounts of B completely eliminate widely extended stacking faults. It is concluded that effects of B other than influencing boundary cohesion are important.

  7. NMR Investigation of Atomic Structure and Dynamics of Bulk Metallic Glasses

    Science.gov (United States)

    2013-09-17

    that, via Al-27 nuclear magnetic resonance (NMR) measurements, that atomic level structures characterized by electric-field-gradient tensors and the...only by the second-order quadrupole effect, and wide satellite transitions 1m m  ( 1/ 2m   ) broadened by the first-order quadrupole ...was used to determine the corresponding linewidths of the central and satellite transitions as noted by the dashed curves in Fig 3.1. In addition, the

  8. 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.

  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. 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

    (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...

  11. Monitoring thermally induced structural deformation and framework decomposition of ZIF-8 through in situ temperature dependent measurements.

    Science.gov (United States)

    Xu, Ben; Mei, Yingjie; Xiao, Zhenyu; Kang, Zixi; Wang, Rongming; Sun, Daofeng

    2017-10-18

    ZIF-8 is an easily synthesized porous material which is widely applied in gas storage/separation, catalysis, and nanoarchitecture fabrication. Thermally induced atomic displacements and the resultant framework deformation/collapse significantly influence the application of ZIF-8, and therefore, in situ temperature dependent FTIR spectroscopy was utilized to study the framework changes during heating in the oxidative environment. The results suggest that ZIF-8 undergoes three transition stages, which are the lattice expansion stage below 200 °C, the "reversible" structural deformation stage from 200 to 350 °C, and the decomposition/collapse stage over 350 °C. Our research indicates that the Zn-N bond breaks at a temperature of 350 °C in the oxidant environment, leading to a drastic deformation of the ZIF-8 structure.

  12. 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

  13. Emergence of coherent localized structures in shear deformations of temperature dependent fluids

    KAUST Repository

    Katsaounis, Theodoros

    2016-11-25

    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}.

  14. Fluid-structure interaction involving large deformations: 3D simulations and applications to biological systems

    Science.gov (United States)

    Tian, Fang-Bao; Dai, Hu; Luo, Haoxiang; Doyle, James F.; Rousseau, Bernard

    2014-02-01

    Three-dimensional fluid-structure interaction (FSI) involving large deformations of flexible bodies is common in biological systems, but accurate and efficient numerical approaches for modeling such systems are still scarce. In this work, we report a successful case of combining an existing immersed-boundary flow solver with a nonlinear finite-element solid-mechanics solver specifically for three-dimensional FSI simulations. This method represents a significant enhancement from the similar methods that are previously available. Based on the Cartesian grid, the viscous incompressible flow solver can handle boundaries of large displacements with simple mesh generation. The solid-mechanics solver has separate subroutines for analyzing general three-dimensional bodies and thin-walled structures composed of frames, membranes, and plates. Both geometric nonlinearity associated with large displacements and material nonlinearity associated with large strains are incorporated in the solver. The FSI is achieved through a strong coupling and partitioned approach. We perform several validation cases, and the results may be used to expand the currently limited database of FSI benchmark study. Finally, we demonstrate the versatility of the present method by applying it to the aerodynamics of elastic wings of insects and the flow-induced vocal fold vibration.

  15. Emergence of Coherent Localized Structures in Shear Deformations of Temperature Dependent Fluids

    Science.gov (United States)

    Katsaounis, Theodoros; Olivier, Julien; Tzavaras, Athanasios E.

    2017-04-01

    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 Katsaounis and Tzavaras (SIAM J Appl Math 69:1618-1643, 2009).

  16. Bulk and surface structure of the clean and adsorbate-covered decagonal Al-Co-Ni quasicrystal

    Energy Technology Data Exchange (ETDEWEB)

    Burkardt, S; Deloudi, S; Erbudak, M; Kortan, A R; Steurer, W [ETH Zurich, 8093 Zurich (Switzerland); Mungan, M [Bogazici University, 34342 Bebek, Istanbul (Turkey)], E-mail: erbudak@phys.ethz.ch

    2008-08-06

    We review our Al adsorption experiments on the tenfold-symmetry surface of the decagonal Al-Co-Ni quasicrystal and present computational simulations of adsorption on a structural model based on a fundamental Al-Co cluster with 20 A diameter, symmetry 10-bar2m, and 8 A periodicity. This cluster is the building unit of {tau}{sup 2}-Al{sub 13}Co{sub 4}, from which, by a sequence of minor changes, the structures of the phases in the stability region of decagonal Al-Co-Ni can be derived. The model used for the decagonal Al{sub 70}Co{sub 15}Ni{sub 15} is an idealized model with a two-layer periodicity (4 A) and no chemical or structural disorder. We find that the bulk and surface properties of this model are in good agreement with experiments. Our molecular-dynamics simulations of Al adsorption reproduce the experimental results and show that by varying the thermal relaxation rates of the adsorbed layer, a variety of different surface morphologies can be achieved. We also present our recent experiments on dissociative adsorption of oxygen on the decagonal surface.

  17. 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.

  18. 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

  19. Femtosecond-laser fabrication of cyclic structures in the bulk of transparent dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Vartapetov, S K; Ganin, D V; Lapshin, K E; Obidin, A Z [Physics Instrumentation Center, A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Troitsk, Moscow Region (Russian Federation)

    2015-08-31

    We report the results of the experiments on developing precision micromachining technology, obtained under the conditions of focusing the pulses of a femtosecond (FS) laser into the volume of a transparent material, which is important, particularly, in the processing of biomaterials in ophthalmology. The implementation conditions and some characteristic features of the special regime of micromachining are determined, when at a definite relation between the sample scanning velocity and the repetition rate of FS pulses the region, destroyed by the laser radiation, is shifted along the optical axis towards the objective and back, forming cyclic patterns inside the sample. It is supposed that the main causes of the damage region shift are the induced modification of the refractive index and the reduction of the damage threshold due to the change in the material density and structure in the microscopic domain, adjacent to the boundary of the cavity produced by the previous pulse. The results of the performed study with the above regime taken into account were used in the technology of precision cutting of crystals, glasses and polymers. The best quality of the cut surface is achieved under the conditions, eliminating the appearance of the cyclic regime. In the samples of polycarbonate, polymethyl methacrylate and fused silica the cylindrical cavities were obtained with the aspect ratio higher than 200, directed along the laser beam, and microcapillaries with the diameter 1 – 2 μm in the direction, perpendicular to this beam. (interaction of laser radiation with matter)

  20. Universal deformation formulas

    OpenAIRE

    Remm, E.; Markl, M.

    2015-01-01

    We give a conceptual explanation of universal deformation formulas for unital associative algebras and prove some results on the structure of their moduli spaces. We then generalize universal deformation formulas to other types of algebras and their diagrams.

  1. Deformation behavior of carbon-fiber reinforced shape-memory-polymer composites used for deployable structures (Conference Presentation)

    Science.gov (United States)

    Lan, Xin; Liu, Liwu; Li, Fengfeng; Pan, Chengtong; Liu, Yanju; Leng, Jinsong

    2017-04-01

    Shape memory polymers (SMPs) are a new type of smart material, they perform large reversible deformation with a certain external stimulus (e.g., heat and electricity). The properties (e.g., stiffness, strength and other mechanically static or quasi-static load-bearing capacity) are primarily considered for conventional resin-based composite materials which are mainly used for structural materials. By contrast, the mechanical actuating performance with finite deformation is considered for the shape memory polymers and their composites which can be used for both structural materials and functional materials. For shape memory polymers and their composites, the performance of active deformation is expected to further promote the development in smart active deformation structures, such as deployable space structures and morphing wing aircraft. The shape memory polymer composites (SMPCs) are also one type of High Strain Composite (HSC). The space deployable structures based on carbon fiber reinforced shape memory polymer composites (SMPCs) show great prospects. Considering the problems that SMPCs are difficult to meet the practical applications in space deployable structures in the recent ten years, this paper aims to research the mechanics of deformation, actuation and failure of SMPCs. In the overall view of the shape memory polymer material's nonlinearity (nonlinearity and stress softening in the process of pre-deformation and recovery, relaxation in storage process, irreversible deformation), by the multiple verifications among theory, finite element and experiments, one obtains the deformation and actuation mechanism for the process of "pre-deformation, energy storage and actuation" and its non-fracture constraint domain. Then, the parameters of SMPCs will be optimized. Theoretical analysis is realized by the strain energy function, additionally considering the interaction strain energy between the fiber and the matrix. For the common resin-based or soft

  2. Effects of Fault Segmentation, Mechanical Interaction, and Structural Complexity on Earthquake-Generated Deformation

    Science.gov (United States)

    Haddad, David Elias

    Earth's topographic surface forms an interface across which the geodynamic and geomorphic engines interact. This interaction is best observed along crustal margins where topography is created by active faulting and sculpted by geomorphic processes. Crustal deformation manifests as earthquakes at centennial to millennial timescales. Given that nearly half of Earth's human population lives along active fault zones, a quantitative understanding of the mechanics of earthquakes and faulting is necessary to build accurate earthquake forecasts. My research relies on the quantitative documentation of the geomorphic expression of large earthquakes and the physical processes that control their spatiotemporal distributions. The first part of my research uses high-resolution topographic lidar data to quantitatively document the geomorphic expression of historic and prehistoric large earthquakes. Lidar data allow for enhanced visualization and reconstruction of structures and stratigraphy exposed by paleoseismic trenches. Lidar surveys of fault scarps formed by the 1992 Landers earthquake document the centimeter-scale erosional landforms developed by repeated winter storm-driven erosion. The second part of my research employs a quasi-static numerical earthquake simulator to explore the effects of fault roughness, friction, and structural complexities on earthquake-generated deformation. My experiments show that fault roughness plays a critical role in determining fault-to-fault rupture jumping probabilities. These results corroborate the accepted 3-5 km rupture jumping distance for smooth faults. However, my simulations show that the rupture jumping threshold distance is highly variable for rough faults due to heterogeneous elastic strain energies. Furthermore, fault roughness controls spatiotemporal variations in slip rates such that rough faults exhibit lower slip rates relative to their smooth counterparts. The central implication of these results lies in guiding the

  3. Mosaic dislocation structures in aluminium crystals deformed in multiple slip at 0.5 to 0.8TM

    DEFF Research Database (Denmark)

    Theyssier, M.C.; Chenal, B.; Driver, J.H.

    1995-01-01

    . The dislocation boundaries are regularly spaced in two families creating a regular structure of cell blocks whose size is very strain rate and temperature dependent. Such cell blocks are also characterised by lattice rotations of alternating sign (often about the transverse axis). For all crystals......Deformation microstructures are characterised in high purity aluminium crystals deformed in multiple slip by channel die compression up to strains of 1.5, temperatures of 473 to 773 K, and strain rates of 10(-1) to 10(-3) s(-1). Four single crystal orientations are examined: three orientations...... have been measured by EBSD (electron back scattered diffraction) and by CBED (convergent beam electron diffraction). The deformation microstructures are subdivided by dislocation boundaries which bound cell blocks oriented at +/- 30 degrees to +/- 55 degrees with respect to the rolling direction...

  4. 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

  5. Controlled assembly of high-order nanoarray metal structures on bulk copper surface by femtosecond laser pulses

    Science.gov (United States)

    Qin, Wanwan; Yang, Jianjun

    2017-07-01

    We report a new one-step maskless method to fabricate high-order nanoarray metal structures comprising periodic grooves and particle chains on a single-crystal Cu surface using femtosecond laser pulses at the central wavelength of 400 nm. Remarkably, when a circularly polarized infrared femtosecond laser pulse (spectrally centered at 800 nm) pre-irradiates the sample surface, the geometric dimensions of the composite structure can be well controlled. With increasing the energy fluence of the infrared laser pulse, both the groove width and particle diameter are observed to reduce, while the measured spacing-to-diameter ratio of the nanoparticles tends to present an increasing tendency. A physical scenario is proposed to elucidate the underlying mechanisms: as the infrared femtosecond laser pulse pre-irradiates the target, the copper surface is triggered to display anomalous transient physical properties, on which the subsequently incident Gaussian blue laser pulse is spatially modulated into fringe-like energy depositions via the excitation of ultrafast surface plasmon. During the following relaxation processes, the periodically heated thin-layer regions can be transferred into the metastable liquid rivulets and then they break up into nanodroplet arrays owing to the modified Rayleigh-like instability. This investigation indicates a simple integrated approach for active designing and large-scale assembly of complexed functional nanostructures on bulk materials.

  6. 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...... of the order of 10 nm, produced by deformation under large sliding loads. Limits to the evolution of microstructural parameters during monotonic loading have been investigated based on a characterization by transmission electron microscopy. Such limits have been observed at an equivalent strain of about 10...

  7. Dynamic Structural Response and Deformations of Monolayer MoS2 Visualized by Femtosecond Electron Diffraction.

    Science.gov (United States)

    Mannebach, Ehren M; Li, Renkai; Duerloo, Karel-Alexander; Nyby, Clara; Zalden, Peter; Vecchione, Theodore; Ernst, Friederike; Reid, Alexander Hume; Chase, Tyler; Shen, Xiaozhe; Weathersby, Stephen; Hast, Carsten; Hettel, Robert; Coffee, Ryan; Hartmann, Nick; Fry, Alan R; Yu, Yifei; Cao, Linyou; Heinz, Tony F; Reed, Evan J; Dürr, Hermann A; Wang, Xijie; Lindenberg, Aaron M

    2015-10-14

    Two-dimensional materials are subject to intrinsic and dynamic rippling that modulates their optoelectronic and electromechanical properties. Here, we directly visualize the dynamics of these processes within monolayer transition metal dichalcogenide MoS2 using femtosecond electron scattering techniques as a real-time probe with atomic-scale resolution. We show that optical excitation induces large-amplitude in-plane displacements and ultrafast wrinkling of the monolayer on nanometer length-scales, developing on picosecond time-scales. These deformations are associated with several percent peak strains that are fully reversible over tens of millions of cycles. Direct measurements of electron-phonon coupling times and the subsequent interfacial thermal heat flow between the monolayer and substrate are also obtained. These measurements, coupled with first-principles modeling, provide a new understanding of the dynamic structural processes that underlie the functionality of two-dimensional materials and open up new opportunities for ultrafast strain engineering using all-optical methods.

  8. Coal Matrix Deformation and Pore Structure Change in High-Pressure Nitrogen Replacement of Methane

    Directory of Open Access Journals (Sweden)

    Xiaofeng Ji

    2018-01-01

    Full Text Available Coal matrix deformation is one of the main controlling factors for coal reservoir permeability changes in nitrogen foam fracturing. The characteristics and mechanism of coal matrix deformation during the process of adsorption/desorption were studied by isothermal adsorption/desorption experiments with methane and nitrogen. Based on the free-energy theories, the Langmuir equation, and elastic mechanics, mathematical models of coal matrix deformation were developed and the deformation characteristics in adsorption/desorption processes were examined. From the study, we deduced that the coal matrix swelling, caused by methane adsorption, was a Langmuir-type relationship with the gas pressure, and exponentially increased as the adsorption quantity increased. Then, the deformation rate and amplitude of the coal matrix decreased gradually with the increase of the pressure. At the following stage, where nitrogen replaces methane, the coal matrix swelling continued but the deformation amplitude decreased, which was only 19.60% of the methane adsorption stage. At the mixed gas desorption stage, the coal matrix shrank with the reduction of pressure and the shrinkage amount changed logarithmically with the pressure, which had the hysteresis effect when compared with the swelling in adsorption. The mechanism of coal matrix deformation was discussed through a comparison of the change of micropores, mesopores, and also part macropores in the adsorption process.

  9. Analysis of Structure and Composition of Bacterial Core Communities in Mature Drinking Water Biofilms and Bulk Water of a Citywide Network in Germany

    Science.gov (United States)

    Henne, Karsten; Kahlisch, Leila; Brettar, Ingrid

    2012-01-01

    The bacterial core communities of bulk water and corresponding biofilms of a more than 20-year-old drinking water network were compared using 16S rRNA single-strand confirmation polymorphism (SSCP) fingerprints based on extracted DNA and RNA. The structure and composition of the bacterial core community in the bulk water was highly similar (>70%) across the city of Braunschweig, Germany, whereas all biofilm samples contained a unique community with no overlapping phylotypes from bulk water. Biofilm samples consisted mainly of Alphaproteobacteria (26% of all phylotypes), Gammaproteobacteria (11%), candidate division TM6 (11%), Chlamydiales (9%), and Betaproteobacteria (9%). The bulk water community consisted primarily of Bacteroidetes (25%), Betaproteobacteria (20%), Actinobacteria (16%), and Alphaproteobacteria (11%). All biofilm communities showed higher relative abundances of single phylotypes and a reduced richness compared to bulk water. Only biofilm communities sampled at nearby sampling points showed similar communities irrespective of support materials. In all of our bulk water studies, the community composition determined from 16S rRNA was completely different from the 16S rRNA gene-based community composition, whereas in biofilms both molecular fractions resulted in community compositions that were similar to each other. We hypothesize that a higher fraction of active bacterial phylotypes and a better protection from oxidative stress in drinking water biofilms are responsible for this higher similarity. PMID:22389373

  10. Analysis of structure and composition of bacterial core communities in mature drinking water biofilms and bulk water of a citywide network in Germany.

    Science.gov (United States)

    Henne, Karsten; Kahlisch, Leila; Brettar, Ingrid; Höfle, Manfred G

    2012-05-01

    The bacterial core communities of bulk water and corresponding biofilms of a more than 20-year-old drinking water network were compared using 16S rRNA single-strand confirmation polymorphism (SSCP) fingerprints based on extracted DNA and RNA. The structure and composition of the bacterial core community in the bulk water was highly similar (>70%) across the city of Braunschweig, Germany, whereas all biofilm samples contained a unique community with no overlapping phylotypes from bulk water. Biofilm samples consisted mainly of Alphaproteobacteria (26% of all phylotypes), Gammaproteobacteria (11%), candidate division TM6 (11%), Chlamydiales (9%), and Betaproteobacteria (9%). The bulk water community consisted primarily of Bacteroidetes (25%), Betaproteobacteria (20%), Actinobacteria (16%), and Alphaproteobacteria (11%). All biofilm communities showed higher relative abundances of single phylotypes and a reduced richness compared to bulk water. Only biofilm communities sampled at nearby sampling points showed similar communities irrespective of support materials. In all of our bulk water studies, the community composition determined from 16S rRNA was completely different from the 16S rRNA gene-based community composition, whereas in biofilms both molecular fractions resulted in community compositions that were similar to each other. We hypothesize that a higher fraction of active bacterial phylotypes and a better protection from oxidative stress in drinking water biofilms are responsible for this higher similarity.

  11. Structural analysis and implicit 3D modelling of Jwaneng Mine: Insights into deformation of the Transvaal Supergroup in SE Botswana

    Science.gov (United States)

    Creus, P. K.; Basson, I. J.; Stoch, B.; Mogorosi, O.; Gabanakgosi, K.; Ramsden, F.; Gaegopolwe, P.

    2018-01-01

    Country rock at Jwaneng Diamond Mine provides a rare insight into the deformational history of the Transvaal Supergroup in southern Botswana. The ca. 235 Ma kimberlite diatremes intruded into late Archaean to Early Proterozoic, mixed, siliciclastic-carbonate sediments, that were subjected to at least three deformational events. The first deformational event (D1), caused by NW-SE directed compression, is responsible for NE-trending, open folds (F1) with associated diverging, fanning, axial planar cleavage. The second deformational event (D2) is probably progressive, involving a clockwise rotation of the principal stress to NE-SW trends. Early D2, which was N-S directed, involved left-lateral, oblique shearing along cleavage planes that developed around F1 folds, along with the development of antithetic structures. Progressive clockwise rotation of far-field forces saw the development of NW-trending folds (F2) and its associated, weak, axial planar cleavage. D3 is an extensional event in which normal faulting, along pre-existing cleavage planes, created a series of rhomboid-shaped, fault-bounded blocks. Normal faults, which bound these blocks, are the dominant structures at Jwaneng Mine. Combined with block rotation and NW-dipping bedding, a horst-like structure on the northwestern limb of a broad, gentle, NE-trending anticline is indicated. The early compressional and subsequent extensional events are consistent throughout the Jwaneng-Ramotswa-Lobatse-Thabazimbi area, suggesting that a large area records the same fault geometry and, consequently, deformational history. It is proposed that Jwaneng Mine is at or near the northernmost limit of the initial, northwards-directed compressional event.

  12. Deformation-Induced Atomic Disordering and Reordering in Alloys with L12 Structure

    Science.gov (United States)

    Pantyukhova, O. D.; Starenchenko, S. V.; Solov'ev, A. N.; Solov'eva, Yu. V.; Starenchenko, V. A.

    2017-10-01

    The paper presents a mathematical model of thermal and strain hardening of alloys having L12 superstructure which allows calculating the atomic long-range order (LRO) parameter depending on the deformation degree under various temperature and loading conditions. The observed non-monotonic change in the atomic LRO parameter during plastic deformation occurs due to the two types of competitive processes. These processes are caused by the motion and accumulation of the deformation defects and their healing due to the migration of point defects of different nature. The competitiveness between these two types of processes leads to the periodical destruction and reconstruction of the atomic LRO parameter, while the equilibrium between them can stabilize it after which it continues to be stable despite the deformation.

  13. Characterizing Cracking and Permanent Deformation; An Attempt for Predicting the End of the Structural Pavement Life

    NARCIS (Netherlands)

    Pramesti, F.P.; Molenaar, A.A.A.; van de Ven, M.F.C.

    2017-01-01

    Durable, therefore sustainable, road needs to attain specific characteristics, among others, resistance to permanent deformation and cracking. Determining the development of both characteristics are important to be able to predict pavement life and performance. In this research, permanent

  14. Characterizing Cracking and Permanent Deformation; An Attempt for Predicting the End of the Structural Pavement Life

    NARCIS (Netherlands)

    Pramesti, F.P.; Molenaar, A.A.A.; van de Ven, M.F.C.

    Durable, therefore sustainable, road needs to attain specific characteristics, among others, resistance to permanent deformation and cracking. Determining the development of both characteristics are important to be able to predict pavement life and performance. In this research, permanent

  15. Structure of deformed silicon and implications for low-cost solar cells

    Science.gov (United States)

    Mardesich, N.; Leipold, M. H.; Turner, G. B.; Digges, T. G., Jr.

    1979-01-01

    The paper reports on an investigation of the microstructure and minority carrier lifetime of silicon in uniaxially compressed silicon samples, the objective of which was to determine if it is feasible to produce silicon solar cells from sheet formed by high temperature deformation. It is reported that recrystallization was found to be incomplete in both fine and large grained materials, and that the major mode of recrystallization appears to be migration of existing boundaries into the deformed regions. Also, minority carrier diffusion length was found to be drastically reduced after deformation, perhaps due to contamination or cooling rate, and recovered only slightly with annealing. It is concluded that these results suggest that high temperature deformation of silicon for direct production of sheet for high efficiency solar cells is not practical. It is noted that potential may exist for its use as a coarse grained substrate.

  16. Applications of Displacement Transfer Functions to Deformed Shape Predictions of the GIII Swept-Wing Structure

    Science.gov (United States)

    Lung, Shun-Fat; Ko, William L.

    2016-01-01

    The displacement transfer functions (DTFs) were applied to the GIII swept wing for the deformed shape prediction. The calculated deformed shapes are very close to the correlated finite element results as well as the measured data. The convergence study showed that using 17 strain stations, the wing-tip displacement prediction error was 1.6 percent, and that there is no need to use a large number of strain stations for G-III wing shape predictions.

  17. Delineating shallow Neogene deformation structures in northeastern Pará State using Ground Penetrating Radar

    Directory of Open Access Journals (Sweden)

    Dilce F. Rossetti

    2003-06-01

    Full Text Available The geological characterization of shallow subsurface Neogene deposits in northeastern Pará State using Ground Penetrating Radar (GPR revealed normal and reverse faults, as well as folds, not yet well documented by field studies. The faults are identified mostly by steeply-dipping reflections that sharply cut the nearby reflections causing bed offsets, drags and rollovers. The folds are recognized by reflections that are highly undulating, configuring broad concave and convex-up features that are up to 50 m wide and 80 to 90 ns deep. These deformation structures are mostly developed within deposits of Miocene age, though some of the faults might continue into younger deposits as well. Although the studied GPR sections show several diffractions caused by trees, differential degrees of moisture, and underground artifacts, the structures recorded here can not be explained by any of these ''noises''. The detailed analysis of the GPR sections reveals that they are attributed to bed distortion caused by brittle deformation and folding. The record of faults and folds are not widespread in the Neogene deposits of the Bragantina area. These GPR data are in agreement with structural models, which have proposed a complex evolution including strike-slip motion for this area from the Miocene to present.A caracterização geológica de depósitos neógenos ocorrentes em sub-superfície rasa no nordeste do Estado do Pará, usando Radar de Penetração no Solo (GPR, revelou a presença de falhas normais e reversas, bem como dobras, ainda não documentadas em estudos de campo prévios. As falhas são identificadas por reflexões inclinadas que cortam bruscamente reflexões vizinhas, causando freqüentes deslocamentos de camadas. As dobras são reconhecidas por reflexões fortemente ondulantes, configurando feições côncavas e convexas que medem até 50 m de amplitude e 80 a 90 m de profundidade. Estas estruturas deformacionais desenvolvem-se, principalmente

  18. Structural properties, deformation behavior and thermal stability of martensitic Ti-Nb alloys

    Energy Technology Data Exchange (ETDEWEB)

    Boenisch, Matthias

    2016-06-10

    Ti-Nb alloys are characterized by a diverse metallurgy which allows obtaining a wide palette of microstructural configurations and physical properties via careful selection of chemical composition, heat treatment and mechanical processing routes. The present work aims to expand the current state of knowledge about martensite forming Ti-Nb alloys by studying 15 binary Ti-c{sub Nb}Nb (9 wt.% ≤ c{sub Nb} ≤ 44.5 wt.%) alloy formulations in terms of their structural and mechanical properties, as well as their thermal stability. The crystal structures of the martensitic phases, α{sup '} and α'', and the influence of the Nb content on the lattice (Bain) strain and on the volume change related to the β → α{sup '}/α'' martensitic transformations are analyzed on the basis of Rietveld-refinements. The magnitude of the shuffle component of the β → α{sup '}/α'' martensitic transformations is quantified in relation to the chemical composition. The largest transformation lattice strains are operative in Nb-lean alloys. Depending on the composition, both a volume dilatation and contraction are encountered and the volume change may influence whether hexagonal martensite α{sup '} or orthorhombic martensite α'' forms from β upon quenching. The mechanical properties and the deformation behavior of martensitic Ti-Nb alloys are studied by complementary methods including monotonic and cyclic uniaxial compression, nanoindentation, microhardness and impulse excitation technique. The results show that the Nb content strongly influences the mechanical properties of martensitic Ti-Nb alloys. The elastic moduli, hardness and strength are minimal in the vicinity of the limiting compositions bounding the interval in which orthorhombic martensite α'' forms by quenching. Uniaxial cyclic compressive testing demonstrates that the elastic properties of strained samples are different than those of unstrained ones

  19. Activation of Actuating Hydrogels with WS2 Nanosheets for Biomimetic Cellular Structures and Steerable Prompt Deformation.

    Science.gov (United States)

    Zong, Lu; Li, Xiankai; Han, Xiangsheng; Lv, Lili; Li, Mingjie; You, Jun; Wu, Xiaochen; Li, Chaoxu

    2017-09-20

    Macroscopic soft actuation is intrinsic to living organisms in nature, including slow deformation (e.g., contraction, bending, twisting, and curling) of plants motivated by microscopic swelling and shrinking of cells, and rapid motion of animals (e.g., deformation of jellyfish) motivated by cooperative nanoscale movement of motor proteins. These actuation behaviors, with an exceptional combination of tunable speed and programmable deformation direction, inspire us to design artificial soft actuators for broad applications in artificial muscles, nanofabrication, chemical valves, microlenses, soft robotics, etc. However, so far artificial soft actuators have been typically produced on the basis of poly(N-isopropylacrylamide) (PNiPAM), whose deformation is motived by volumetric shrinkage and swelling in analogue to plant cells, and exhibits sluggish actuation kinetics. In this study, alginate-exfoliated WS2 nanosheets were incorporated into ice-template-polymerized PNiPAM hydrogels with the cellular microstructures which mimic plant cells, yet the prompt steerable actuation of animals. Because of the nanosheet-reinforced pore walls formed in situ in freezing polymerization and reasonable hierarchical water channels, this cellular hybrid hydrogel achieves super deformation speed (on the order of magnitude of 10° s), controllable deformation direction, and high near-infrared light responsiveness, offering an unprecedented platform of artificial muscles for various soft robotics and devices (e.g., rotator, microvalve, aquatic swimmer, and water-lifting filter).

  20. Density Functional Investigation of the Thermodynamic Stability of Lithium Oxide Bulk Crystalline Structures as a Function of Oxygen Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Lau, Kah Chun; Curtiss, Larry A.; Greeley, Jeffrey P.

    2011-12-01

    Density functional theory is used together with classical statistical mechanical analyses to investigate the thermodynamic stability of bulk crystalline LiO2, Li2 O, and Li2O2 as a function of the oxygen environment. The results indicate that lithium peroxide (Li2O2(s)) and superoxide (LiO2(s)) are likely to be stable only under O2-rich conditions with high oxygen partial pressures (PΟ2), whereas Li2O is the most stable at ambient conditions. Additionally, the trends in the density functional calculated equilibrium potential for an ideal reversible Li-O2 couple can be described by an analytical equation as a function of pressure and temperature. As part of this work, we have also calculated the structure and thermodynamics for lithium superoxide. It is found to be stable with respect to lattice vibrations, with an O-O stretching vibration mode very similar to that of the isolated LiO2 molecule and to the O2 - ion radical.

  1. Density functional investigation of the thermodynamic stability of lithium oxide bulk crystalline structures as a function of oxygen pressure.

    Energy Technology Data Exchange (ETDEWEB)

    Lau, K. C.; Curtiss, L. A.; Greeley, J. (Center for Nanoscale Materials); ( MSD)

    2011-01-01

    Density functional theory is used together with classical statistical mechanical analyses to investigate the thermodynamic stability of bulk crystalline LiO{sub 2}, Li{sub 2}O, and Li{sub 2}O{sub 2} as a function of the oxygen environment. The results indicate that lithium peroxide (Li{sub 2}O{sub 2(s)}) and superoxide (LiO{sub 2(s)}) are likely to be stable only under O{sub 2}-rich conditions with high oxygen partial pressures (P?{sub 2}), whereas Li{sub 2}O is the most stable at ambient conditions. Additionally, the trends in the density functional calculated equilibrium potential for an ideal reversible Li-O{sub 2} couple can be described by an analytical equation as a function of pressure and temperature. As part of this work, we have also calculated the structure and thermodynamics for lithium superoxide. It is found to be stable with respect to lattice vibrations, with an O-O stretching vibration mode very similar to that of the isolated LiO{sub 2} molecule and to the O{sub 2}{sup -} ion radical.

  2. 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

  3. Analogue modelling of deformation structures at Mt Cameroon analysed with a digital image correlation technique

    Science.gov (United States)

    Kervyn, Matthieu; Walter, Thomas R.; van Wyk de Vries, Benjamin; Ernst, Gerald G. J.

    2010-05-01

    Mt. Cameroon is a large, 4090 m high, continental volcano. It is characterized by repetitive basaltic lava flow eruptions, the most recent ones occurring in 1999 and 2000. Upper flanks of Mt Cameroon are exceptionally steep (~30°) for a lava-dominated volcano and are constrained by sharp breaks-in-slope. Field work enabled to identified well-defined inward-dipping structures bordering a flat summit plateau and thrust faults associated with topographic terraces around Mt Cameroon's base, suggesting summit subsidence and gravitational spreading of the volcano flanks above its sedimentary base. To better understand the structural configuration and morphology observed, scaled analogue experiments were designed. A volcanic ridge, made out of fine quartz sand, was let spread under gravitational forces above a ductile silicone layer. Experiments were conducted in 2D and 3D configurations. A digital image correlation (DIC) procedure was used to record fault formation and evolution through time. 3D spreading of an elongated edifice favors displacement perpendicular to the long axis, and formation of a summit graben and basal thrusts or folds parallel to this axis. Results of the DIC highlights the strain concentration in the central part of the main graben and along specific strike-slip faults bordering secondary grabens. This deformation is however not associated with slope increase or instabilities. 2D spreading of a volcanic ridge between two glass panes is associated either with two outward-dipping listric normal faults and inward-dipping antithetic faults or with two sets of deep and shallow normal faults, defining a central graben and forming steep mid-slopes with local instabilities, depending on the thickness of the underlying ductile material. Results from the experiments are compared with structural lineaments mapped at Mt Cameroon. It is concluded that the elongated morphology of Mt Cameroon promotes directional spreading perpendicular to its long axis, probably

  4. Local microstructure and flow stress in deformed metals

    Science.gov (United States)

    Zhang, X.; Hansen, N.; Nielsen, C. V.

    2017-07-01

    The microstructure and flow stress of metals are related through many well-known strength-structure relationships based on structural parameters, where grain size and dislocation density are examples. In heterogeneous structures, the local stress and strain are important as they will affect the bulk properties. A microstructural method is presented which allows the local stress in a deformed metal to be estimated based on microstructural parameters determined by an EBSD analysis. These parameters are the average spacing of deformation introduced boundaries and the fraction of high angle boundaries. The method is demonstrated for two heterogeneous structures: (i) a gradient (sub)surface structure in steel deformed by shot peening; (ii) a heterogeneous structure introduced by friction between a tool and a workpiece of aluminum. Flow stress data are calculated based on the microstructural analysis, and validated by hardness measurement and 2D numerical simulations. A good agreement is found over a plastic strain range from ∼1 to 5.

  5. 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.

  6. Structural modifications induced by compressive plastic deformation in single-step and sequentially irradiated UHMWPE for hip joint components.

    Science.gov (United States)

    Puppulin, Leonardo; Sugano, Nobuhiko; Zhu, Wenliang; Pezzotti, Giuseppe

    2014-03-01

    Structural modifications were studied at the molecular scale in two highly crosslinked UHMWPE materials for hip-joint acetabular components, as induced upon application of (uniaxial) compressive strain to the as-manufactured microstructures. The two materials, quite different in their starting resins and belonging to different manufacturing generations, were a single-step irradiated and a sequentially irradiated polyethylene. The latter material represents the most recently launched gamma-ray-irradiated polyethylene material in the global hip implant market. Confocal/polarized Raman spectroscopy was systematically applied to characterize the initial microstructures and the microstructural response of the materials to plastic deformation. Crystallinity fractions and preferential orientation of molecular chains have been followed up during in vitro deformation tests on unused cups and correlated to plastic strain magnitude and to the recovery capacity of the material. Moreover, analyses of the in vivo deformation behavior of two short-term retrieved hip cups are also presented. Trends of preferential orientation of molecular chains as a function of residual strain were similar for both materials, but distinctly different in their extents. The sequentially irradiated material was more resistant to plastic deformation and, for the same magnitude of residual plastic strain, possessed a higher capacity of recovery as compared to the single-step irradiated one. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Process Modelling of Curing Process-Induced Internal Stress and Deformation of Composite Laminate Structure with Elastic and Viscoelastic Models

    Science.gov (United States)

    Li, Dongna; Li, Xudong; Dai, Jianfeng

    2017-08-01

    In this paper, two kinds of transient models, the viscoelastic model and the linear elastic model, are established to analyze the curing deformation of the thermosetting resin composites, and are calculated by COMSOL Multiphysics software. The two models consider the complicated coupling between physical and chemical changes during curing process of the composites and the time-variant characteristic of material performance parameters. Subsequently, the two proposed models are implemented respectively in a three-dimensional composite laminate structure, and a simple and convenient method of local coordinate system is used to calculate the development of residual stresses, curing shrinkage and curing deformation for the composite laminate. Researches show that the temperature, degree of curing (DOC) and residual stresses during curing process are consistent with the study in literature, so the curing shrinkage and curing deformation obtained on these basis have a certain referential value. Compared the differences between the two numerical results, it indicates that the residual stress and deformation calculated by the viscoelastic model are more close to the reference value than the linear elastic model.

  8. Soft-sediment deformation structures in cores from lacustrine slurry deposits of the Late Triassic Yanchang Fm. (central China

    Directory of Open Access Journals (Sweden)

    Yang Renchao

    2016-09-01

    Full Text Available The fine-grained autochthonous sedimentation in the deep part of a Late Triassic lake was frequently interrupted by gravity-induced mass flows. Some of these mass flows were so rich in water that they must have represented slurries. This can be deduced from the soft-sediment deformation structures that abound in cores from these lacustrine deposits which constitute the Yanchang Fm., which is present in the Ordos Basin (central China.

  9. A constitutive model of cyclic viscoplasticity considering changes in subsequent viscoplastic deformation due to the evolution of dislocation structures

    OpenAIRE

    T. Mayama; Sasaki, K.; Ishikawa, H.

    2007-01-01

    This paper presents a unified constitutive model for cyclic viscoplasticity and changes occurring in subsequent viscoplastic deformation due to the evolution of dislocation structures. The model considers the viscoplastic potential and a modified Ramberg–Osgood law. Stress is assumed to divide into three components: back stress (the center of the yield surface), flow stress (the radius of the yield surface), and viscous stress (overstress). The modification of the Ramberg–Osgood law is carrie...

  10. Modelling and structural analysis of skull/cranial implant: beyond mid-line deformities.

    Science.gov (United States)

    Bogu, V Phanindra; Kumar, Y Ravi; Kumar Khanara, Asit

    2017-01-01

    This computational study explores modelling and finite element study of the implant under Intracranial pressure (ICP) conditions with normal ICP range (7 mm Hg to 15 mm Hg) or increased ICP (>I5 mm Hg). The implant fixation points allow implant behaviour with respect to intracranial pressure conditions. However, increased fixation points lead to variation in deformation and equivalent stress. Finite element analysis is providing a valuable insight to know the deformation and equivalent stress. The patient CT data (Computed Tomography) is processed in Mimics software to get the mesh model. The implant is modelled by using modified reverse engineering technique with the help of Rhinoceros software. This modelling method is applicable for all types of defects including those beyond the middle line and multiple ones. It is designed with eight fixation points and ten fixation points to fix an implant. Consequently, the mechanical deformation and equivalent stress (von Mises) are calculated in ANSYS 15 software with distinctive material properties such as Titanium alloy (Ti6Al4V), Polymethyl methacrylate (PMMA) and polyether-ether-ketone (PEEK). The deformation and equivalent stress results are obtained through ANSYS 15 software. It is observed that Ti6Al4V material shows low deformation and PEEK material shows less equivalent stress. Among all materials PEEK shows noticeably good result. Hence, a concept was established and more clinically relevant results can be expected with implementation of realistic 3D printed model in the future. This will allow physicians to gain knowledge and decrease surgery time with proper planning.

  11. Thermomechanical Modeling of Laser-Induced Structural Relaxation and Deformation of Glass: Volume Changes in Fused Silica at High Temperatures [Thermo-mechanical modeling of laser-induced structural relaxation and deformation of SiO2 glass

    Energy Technology Data Exchange (ETDEWEB)

    Vignes, Ryan M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Ignition Facility and Photon Sciences; Soules, Thomas F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Ignition Facility and Photon Sciences; Stolken, James S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Ignition Facility and Photon Sciences; Settgast, Randolph R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Ignition Facility and Photon Sciences; Elhadj, Selim [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Ignition Facility and Photon Sciences; Matthews, Manyalibo J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). National Ignition Facility and Photon Sciences; Mauro, J.

    2012-12-17

    In a fully coupled thermomechanical model of the nanoscale deformation in amorphous SiO2 due to laser heating is presented. Direct measurement of the transient, nonuniform temperature profiles was used to first validate a nonlinear thermal transport model. Densification due to structural relaxation above the glass transition point was modeled using the Tool-Narayanaswamy (TN) formulation for the evolution of structural relaxation times and fictive temperature. TN relaxation parameters were derived from spatially resolved confocal Raman scattering measurements of Si–O–Si stretching mode frequencies. These thermal and microstructural data were used to simulate fictive temperatures which are shown to scale nearly linearly with density, consistent with previous measurements from Shelby et al. Volumetric relaxation coupled with thermal expansion occurring in the liquid-like and solid-like glassy states lead to residual stresses and permanent deformation which could be quantified. But, experimental surface deformation profiles between 1700 and 2000 K could only be reconciled with our simulation by assuming a roughly 2 × larger liquid thermal expansion for a-SiO2 with a temperature of maximum density ~150 K higher than previously estimated by Bruckner et al. Calculated stress fields agreed well with recent laser-induced critical fracture measurements, demonstrating accurate material response prediction under processing conditions of practical interest.

  12. Elastic-plastic deformation of fiber composites with a tetragonal structure

    Energy Technology Data Exchange (ETDEWEB)

    Makarova, E.IU.; Svistkova, L.A. (Permskii Politekhnicheskii Institut, Perm (USSR))

    1991-02-01

    Results of numerical solutions are presented for elastic-plastic problems concerning arbitrary loading of unidirectional composites in the transverse plane. The nucleation and evolution of microplastic zones in the matrix and the effect of this process on the macroscopic characteristics of the composite are discussed. Attention is also given to the effect of the fiber shape on the elastic-plastic deformation of the matrix and to deformation paths realized in simple microdeformation processes. The discussion is illustrated by results obtained for a composite consisting of a VT1-0 titanium alloy matrix reinforced by Ti-Mo fibers.

  13. Piezoelectric and deformation potential effects of strain-dependent luminescence in semiconductor quantum well structures

    DEFF Research Database (Denmark)

    Zhang, Aihua; Peng, Mingzeng; Willatzen, Morten

    2017-01-01

    , in the framework of the 6 × 6 k·p Hamiltonian for the valence states, to directly assess the interplay between the spin-orbit coupling and the strain-induced deformation potential for the interband momentum-matrix element. We numerically addressed problems of both the infinite and IQWs with piezoelectric fields...... to elucidate the effects of the piezoelectric potential and the deformation potential on the strain-dependent luminescence. The experimentally measured photoluminescence variatio½n as a function of pressure can be qualitatively explained by the theoretical results....

  14. Development and structural characterization of exchange-spring-like nanomagnets in (Fe,Co)-Pt bulk nanocrystalline alloys

    Energy Technology Data Exchange (ETDEWEB)

    Crisan, O.; Crisan, A.D.; Mercioniu, I. [National Institute for Materials Physics, P.O. Box MG-7, 077125 Magurele, Bucharest (Romania); Nicula, R. [Empa, Swiss Federal Laboratories for Materials Science and Technology, Advanced Materials Processing, Feuerwerkerstr. 39, CH-3602 Thun (Switzerland); Vasiliu, F., E-mail: fvasiliu@infim.ro [National Institute for Materials Physics, P.O. Box MG-7, 077125 Magurele, Bucharest (Romania)

    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 L1{sub 0} 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 L1{sub 0} phases. X-ray diffraction was used to characterize the phase structure and to obtain the structural parameters of interest for L1{sub 0} ordering. In the as-cast state, the co-existence of hard magnetic CoFePt and CoPt L1{sub 0} 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 L1{sub 0} phases (disorder–order transition). The resulting CoPt and CoFePt L1{sub 0} 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 L1{sub 0} 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

  15. Electronic structure of Fe1.08Te bulk crystals and epitaxial FeTe thin films on Bi2Te3

    DEFF Research Database (Denmark)

    Arnold, Fabian; Warmuth, Jonas; Michiardi, Matteo

    2018-01-01

    The electronic structure of thin films of FeTe grown on Bi2Te3 is investigated using angle-resolved photoemission spectroscopy, scanning tunneling microscopy and first principles calculations. As a comparison, data from cleaved bulk Fe1.08Te taken under the same experimental conditions is also...... presented. Due to the substrate and thin film symmetry, FeTe thin films grow on Bi2Te3 in three domains, rotated by 0 degrees, 120 degrees, and 240 degrees. This results in a superposition of photoemission intensity from the domains, complicating the analysis. However, by combining bulk and thin film data....... By tracking the change of substrate electronic structure upon film growth, we find indications of an electron transfer from the FeTe film to the substrate. No significant change of the film's electronic structure or doping is observed when alkali atoms are dosed onto the surface. This is ascribed to the film...

  16. 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

    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...

  17. Unravelling the structural and chemical features influencing deformation-induced martensitic transformations in steels

    NARCIS (Netherlands)

    Tirumalasetty, G.K.; Van Huis, M.A.; Kwakernaak, C.; Sietsma, J.; Sloof, W.G.; Zandbergen, H.W.

    2013-01-01

    A combination of Electron Back-Scattered Diffraction (EBSD) and high-sensitivity Electron Probe Micro-Analysis (EPMA) was used to correlate the changes in microstructural features upon deformation with local chemical composition in Transformation-Induced Plasticity steels. A novel cleaning procedure

  18. Effects of Fault Segmentation, Mechanical Interaction, and Structural Complexity on Earthquake-Generated Deformation

    Science.gov (United States)

    Haddad, David Elias

    2014-01-01

    Earth's topographic surface forms an interface across which the geodynamic and geomorphic engines interact. This interaction is best observed along crustal margins where topography is created by active faulting and sculpted by geomorphic processes. Crustal deformation manifests as earthquakes at centennial to millennial timescales. Given that…

  19. Editorial: Introduction to the Special Issue ;Slope Tectonics: Inherited Structures, Morphology of Deformation and Catastrophic Failure;

    Science.gov (United States)

    Hermanns, R. L.; Oppikofer, T.; Jaboyedoff, M.; Clague, J. J.; Scarascia-Mugnozza, G.

    2017-07-01

    The "Conference on Slope Tectonics" has become an international scientific meeting point to present and discuss a variety of topics related to slope deformation and the deposits of related failures. The first conference took place on February 15-16, 2008 at University of Lausanne (Switzerland). It was followed by a second conference on September 6-10, 2011, in Austria (organized by the Geological Survey of Austria) and a third on September 8-12, 2014, in Norway (organized by the Geological Survey of Norway). The two later events included field trips. It has become a tradition that selected papers from these conference are published - papers from the first conference were published by the Geological Society as Special Publication 351 (Jaboyedoff, 2011), and those from the second conference were published in a special issue of Tectonophysics (Baron and Jaboyedoff, 2013). This special issue of Geomorphology is a collection of papers presented at the Norwegian Conference on Slope Tectonics. This collection of papers focuses on the role of tectonics in gravitationally induced rock-slope instabilities. The slopes either deform over long periods as deep-seated gravitational slope deformation (DSGSD) or more rapidly as rockslides or rock avalanches. The reconstruction of slope deformation is an integral part of the studies captured in this special issue.

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

    DEFF Research Database (Denmark)

    Fengxiang, Lin; Godfrey, A.; Juul Jensen, Dorte

    2010-01-01

    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....

  1. Kinetics deformation of current-voltage characteristics of the varistor oxide structures due to overcharging of the localized states

    Directory of Open Access Journals (Sweden)

    Tonkoshkur A. S.

    2014-12-01

    Full Text Available Prolonged exposure of zinc oxide varistors to the electrical load leads to current-voltage characteristics (CVC deformation, which is associated with a change in the height and width of the intergranular barriers, which are main structural element of the varistors. Polarization phenomena in zinc oxide ceramics are studied in a number of works, but those are mainly limited to the study of the physics of the CVC deformation process and to determining the parameters of localized electronic states involved in this process. This paper presents the results on the simulation of the deformation of pulse CVC of a separate intergranular potential barrier at transient polarization/depolarization, associated with recharging of surface electronic states (SES, which cause this barrier. It is found that at high density of SES their degree of electron filling is small and the effect of DC voltage leads to a shift of pulse current-voltage characteristics into the region of small currents. Conversely, the low density SES are almost completely filled with electrons, and after crystallite polarization CVC is shifted to high currents. Experimental studies have confirmed the possibility of applying the discovered laws to ceramic varistor structures. The proposed model allows interpreting the «anomalous» effects (such as increase in the classification voltage and reduction of active losses power observed during the varistors accelerated aging test.

  2. Pyrite deformation and connections to gold mobility: insight from micro-structural analysis and trace element mapping

    Science.gov (United States)

    Dubosq, Renelle; Rogowitz, Anna; Lawley, Christopher; Schneider, David; Jackson, Simon

    2017-04-01

    Pyrite is an important and ubiquitous gold-bearing phase in many orogenic gold deposits making the study of its deformation behaviour under metamorphic conditions crucial to the understanding of gold (re)mobilization. However, pyrite deformation mechanisms and their influence on the retention or release of trace elements during deformation and metamorphism remain poorly understood. We propose a syn- to post-peak metamorphic and deformation driven gold upgrading model where gold is remobilized through deformation-induced diffusion pathways in the form of substructures in pyrite. The middle amphibolite facies assemblage (actinolite-biotite-plagioclase-almandine) of the Detour Lake deposit (Canada) makes it an ideal study area due to maximum temperatures reaching 550°C, exceeding the conditions for plastic deformation in pyrite (450°C). The world-class Detour Lake deposit, containing 16.4 Moz of Au at 1 g/t, is a Neoarchean orogenic gold ore body located in the northern Abitibi district within the Superior Province. The mine is situated along the high strain, sub-vertical ductile-brittle Sunday Lake Deformation Zone (SLDZ) parallel to the broadly E-W trending Abitibi greenstone belt. Herein we combine orientation contrast (OC) forescatter imaging, electron backscatter diffraction (EBSD) and 2D laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) trace element pyrite mapping to evaluate the influence of pyrite brittle and plastic deformation on the release of trace elements during syn-metamorphic gold remobilization. Local misorientation patterns in pyrite exhibit parallel bands that can be described by continuous rotation around one of the axes, whereas higher strain areas reveal more heterogeneous misorientation patterns and the development of low-angle grain boundaries with late fractures indicative of dislocation creep and strain hardening. These late fractures are an important micro-structural setting for gold and clusters of precious

  3. Comparison of Interfacial Strengthening in Creep Deformation and Radiation Damage Processes of Advanced Structural Materials for Nuclear Applications

    Science.gov (United States)

    Zhu, Hanliang

    2018-02-01

    The mechanisms for microstructural strengthening in creep deformation and radiation damage processes of advanced structural materials for nuclear applications are compared. During creep and irradiation, various defects are generated and move in the microstructure. Any microstructural features that can retard such defect movement may improve both creep and radiation damage resistance. Interfaces in the microstructure are important barriers for preventing defect motion. To achieve ultrahigh strength and enhanced radiation damage resistance, an extremely high density of interfaces has been designed in recently developed nanostructured materials. However, interface-mediated processes may govern the deformation of these materials, decreasing their creep properties. Methods for improving the creep resistance of nanostructured materials are reviewed and discussed.

  4. Temperature Distribution and Thermal Deformation of the Crystallization Roller Based on the Direct Thermal-Structural Coupling Method

    Science.gov (United States)

    Pan, Liping; He, Zhu; Li, Baokuan; Zhou, Kun; Sun, Ke

    2017-03-01

    The temperature distribution and the thermal deformation of the crystallization roller have a significant effect on the forming process of the thin steel strip. Finite element analysis has been used to simulate the temperature distribution and the thermal deformation in a crystallization roller through the direct thermal-structural coupling analysis method. Various parameters, such as different rotational velocities, diverse locations of cooling water pipes, and typical velocities of cooling water have been systematically investigated. It is found that the temperature and the equivalent stress of the outer surface reach the steady state after 30 s of rotations, and they are influenced remarkably by the factors of rotational velocity and cooling water pipe depth. Meanwhile, the radial displacement approaches the steady state after 300 s of revolutions and is significantly affected by the cooling water velocity.

  5. Role of Static and Cyclic Deformation on the Corrosion Behavior of a Magnesium-Steel Structural Joint

    Science.gov (United States)

    Gholami Bazehhour, B.; Adlakha, I.; Solanki, K. N.

    2017-11-01

    In this article, a numerical investigation examining the influence of various mechanical loading scenarios on the corrosion behavior of a galvanic joint formed between a magnesium alloy and mild steel was carried out. A wide spectrum of mechanical conditions were examined to facilitate the development of a comprehensive understanding on the effect of mechanical deformation during galvanic corrosion. In general, we found that the onset of nonlinear deformation drastically accelerates the localized corrosion. Furthermore, subjecting the galvanic joint to alternating corrosion and fatigue loading was found to increase the observed localized corrosion drastically. Finally, the simulation results are discussed with respect to the identification and description of the detrimental physical phenomena that undermine the structural integrity of joints subjected to various mechanical loading scenarios.

  6. Micro-Structural Evolution and Size-Effects in Plastically Deformed Single Crystals: Strain Gradient Continuum Modeling

    DEFF Research Database (Denmark)

    El-Naaman, Salim Abdallah

    the macroscopic effects related to strain gradients, most predict smooth micro-structures. The evolution of dislocation micro-structures, during plastic straining of ductile crystalline materials, is highly complex and nonuniform. Published experimental measurements on deformed metal crystals show distinct...... pattern formation, in which dislocations, of the geometrically necessary kind, are arranged in wall and cell structures. This particular subset of signed dislocations, which have a net Burg-ers vector, are the main source for the observed size-effects and are directly linked to the gradients in plastic...... strain. It is clear that many challenges are associated with modeling dislocation structures, within a framework based on continuum fields, however, since the strain gradient effects are attributed to the dislocation micro-structure, it is a natural step, in the further development of gradient theories...

  7. Three-dimensional grain structure of sintered bulk strontium titanate from X-ray diffraction contrast tomography

    DEFF Research Database (Denmark)

    Syha, M.; Rheinheimer, W.; Bäurer, M.

    2012-01-01

    The three-dimensional grain boundary network of sintered bulk strontium titanate is reconstructed using X-ray diffraction contrast tomography, a non-destructive technique for determining the grain shape and crystallographic orientation in polycrystals that is ideally suited for detailed studies...

  8. Pleomorphic structural imperfections caused by pulsed Bi-implantation in the bulk and thin-film morphologies of TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Zatsepin, D.A. [M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 620990 Yekaterinburg (Russian Federation); Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation); Boukhvalov, D.W., E-mail: danil@hanyang.ac.kr [Department of Chemistry, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 04763 (Korea, Republic of); Theoretical Physics and Applied Mathematics Department, Ural Federal University, Mira Street 19, 620002 Yekaterinburg (Russian Federation); Kurmaev, E.Z. [M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 620990 Yekaterinburg (Russian Federation); Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation); Gavrilov, N.V. [Institute of Electrophysics, Russian Academy of Sciences, Ural Branch, 620990 Yekaterinburg (Russian Federation); Kim, S.S. [School of Materials Science and Engineering, Inha University, Incheon 22212 (Korea, Republic of); Zhidkov, I.S. [Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation)

    2016-08-30

    Highlights: • Bismuth doped bulk and thin-filmTiO{sub 2} host were examined experimentally and theoretically applying XPS and DFT methods. • Combination of bismuth ions and oxygen vacancies is the propagated type of defects. • In the bulk morphology of TiO{sub 2} both experiment and theory demonstrate the formation of Bi{sub 2}O{sub 3}-like structures. • An aggregation of Bi-impurities occurs on the surfaces of thin-films. - Abstract: The results of combined experimental and theoretical study of pleomorphic substitutional and clustering effects in Bi-doped TiO{sub 2} hosts (bulk and thin-film morphologies) are presented. Bi-doping of the bulk and thin-film titanium dioxide was made with help of pulsed ion-implantation (E{sub Bi}{sup +} = 30 keV, D = 1 × 10{sup 17} cm{sup −2}) without posterior tempering. The X-ray photoelectron spectroscopy (XPS) qualification (core-levels and valence bands) and Density-Functional Theory (DFT) calculations were employed in order to study the electronic structure of Bi-ion implanted TiO{sub 2} samples. According to XPS data obtained and DFT calculations, the Bi → Ti cation substitution occurs in Bi-implanted bulk TiO{sub 2}, whereas in the thin-film morphology of TiO{sub 2}:Bi the Bi-atoms have metal-like clusters segregation tendency. Based on the combined XPS and DFT considerations the possible reasons and mechanism for the observed effects are discussed. It is believed that established peculiarities of bismuth embedding into employed TiO{sub 2} hosts are mostly the sequence of pleomorphic origin for the formed “bismuth–oxygen” chemical bonding.

  9. Study on acoustic emission source localization of 16Mn structural steel of high temperature deformation

    Science.gov (United States)

    Zhang, Yubo; Deng, Muhan; Yang, Rui; Jin, Feixiang

    2017-09-01

    The location technique of acoustic emission (AE) source for deformation damage of 16Mn steel in high temperature environment is studied by using linear time-difference-of-arrival (TDOA) location method. The distribution characteristics of strain induced acoustic emission source signals at 20°C and 400°C of tensile specimens were investigated. It is found that the near fault has the location signal of the cluster, which can judge the stress concentration and cause the fracture.

  10. Existing Resources, Standards, and Procedures for Precise Monitoring and Analysis of Structural Deformations. Volume 2. Appendices

    Science.gov (United States)

    1992-09-01

    comporte- bed has to be sta~e. The management appoints qualifie ment anormal au barrage, siismes, glissernents de terrain , professional enginees as...tots qu’un compor- vated. ternent anormal du barrage. un siisme, un glissement do 3 If the degree of preparedness 4 has been ordered for the terrain . un...KI, FINLAND, 199 0 DEFORMATION MONITORING, ANALYSIS, AND PREDICTION - STATUS REPORT L.A SURVEILLANCE, L’ANALYSE, ET LA PREDICTION DE D#FORMATIONS - UN

  11. Structure and performance of anisotropic nanocrystalline Nd-Fe-B magnets fabricated by high-velocity compaction followed by deformation

    Science.gov (United States)

    Zhao, L. Z.; Deng, X. X.; Yu, H. Y.; Guan, H. J.; Li, X. Q.; Xiao, Z. Y.; Liu, Z. W.; Greneche, J. M.

    2017-12-01

    High-velocity compaction (HVC) has been proposed as an effective approach for the fabrication of nanocrystalline Nd-Fe-B magnets. In this work, the effect of powder size on the density of HVCed magnets has been studied and the anisotropic nanocrystalline Nd-Fe-B magnets were prepared by HVC followed by hot deformation (HD). It is found that a proper particle size range is beneficial to high density. The investigations on the microstructure, magnetic domain structure, and hyperfine structure, indicate that the deformed grain structure and the magnetic domain structure with uniform paramagnetic grain boundary phase give good magnetic properties of HVC + HDed magnets. These magnets also have good mechanical and anti-corrosion properties. The results indicate that HVC is not only a near-net-shape, room temperature and binder-free process but is also able to maintain uniform nanostructure and to achieve good magnetic properties in both isotropic and anisotropic magnets. As a result, HVC can be employed as an ideal alternative process for bonding or hot pressing for the conventional MQI, MQII and MQIII magnets.

  12. A triaxial tensile deformation-induced nanoporous structure of aluminium: estimation of surface area, solid volume, and dimensionless aspect ratio.

    Science.gov (United States)

    Kumar, Sunil; Das, Suchandan K

    2017-08-09

    Nanoporous aluminium has great importance for large scale production of automobile and aerospace spare parts due to its lightweight and non-corrosive nature. It is also suitable for various packaging applications of edible things, electronic components, and medicines. We have used triaxial tensile deformation methodology to create a nanoporous structure of aluminium using molecular dynamics simulation. The surface area and solid volume have been calculated to characterize the 3-D nanoporous structure of aluminium. We have quantitatively characterized the growth and coalescences of the nanoporous structure via estimation of the number of nanopores, nanopore diameters, and dimensionless aspect-ratios (surface area to volume ratio). A high aspect ratio indicates a large number of tiny nanopores in the 3-D nanoporous structure of aluminium. We have found that crystalline aluminium (under ambient condition) significantly depicts a smaller aspect ratio as compared to amorphous aluminium during triaxial tensile deformation. We believe that the results of this study will provide new understanding to the researchers for the design and characterization of nanoporous metals.

  13. 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.

  14. Structural differences existing in bulk and nanoparticles of Y{sub 2}Sn{sub 2}O{sub 7}: Investigated by experimental and theoretical methods

    Energy Technology Data Exchange (ETDEWEB)

    Nigam, Sandeep, E-mail: snigam@barc.gov.in [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Sudarsan, V., E-mail: vsudar@barc.gov.in [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Majumder, C.; Vatsa, R.K. [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2013-04-15

    Present manuscript deals with the structural changes associated with transformation of bulk Y{sub 2}Sn{sub 2}O{sub 7} into nanoparticles of Y{sub 2}Sn{sub 2}O{sub 7}. Nanoparticles of Y{sub 2}Sn{sub 2}O{sub 7} both undoped and Eu{sup 3+} doped, were prepared at a relatively low temperature (700 °C) and investigated for their structural and luminescence properties and compared them with that of bulk Y{sub 2}Sn{sub 2}O{sub 7} sample prepared by the solid-state method at 1300 °C. Significant distortion in geometry and electron density distribution around Y{sup 3+}/Eu{sup 3+} ions in nanoparticles are confirmed from the Rietveld refinement of the powder X-ray diffraction patterns and theoretical calculations based on the density functional theory (DFT). The SnO{sub 6} octahedron in Y{sub 2}Sn{sub 2}O{sub 7} is more expanded in nanoparticles compared to bulk. Iso-surface density distribution reveals that while bulk sample shows typical ionic feature in Y/Eu--O bonds, nanoparticle sample shows sharing of electron density along bond axis pertaining to covalent character. These inferences are further supported by the doped Eu{sup 3+} luminescence and calculated Ω{sub 2} and Ω{sub 4} parameters. - Graphical abstract: YO{sub 8} scalenohedron present in bulk and nanoparticles of Y{sub 2}Sn{sub 2}O{sub 7}.Variation of the electron density around Y{sup 3+} ions in YO{sub 8} polyhedron is also shown in bulk and nanoparticles of Y{sub 2}Sn{sub 2}O{sub 7}. The difference in the extent of ionic/covalent nature of the Y--O bond is clearly seen the contour plot of electron density. Highlights: ► YO{sub 8} scalenohedron is axially and equatorially distorted in Y{sub 2}Sn{sub 2}O{sub 7} nanoparticles. ► Enlargement of SnO{sub 6} octahedron in nanoparticles of Y{sub 2}Sn{sub 2}O{sub 7} compared to bulk. ► Less symmetric charge distribution around Y{sup 3+} ions in Y{sub 2}Sn{sub 2}O{sub 7} nanoparticles.

  15. Measuring structure deformations of a composite glider by optical means with on-ground and in-flight testing

    Science.gov (United States)

    Bakunowicz, Jerzy; Święch, Łukasz; Meyer, Ralf

    2016-12-01

    In aeronautical research experimental data sets of high quality are essential to verify and improve simulation algorithms. For this reason the experimental techniques need to be constantly refined. The shape, movement or deformation of structural aircraft elements can be measured implicitly in multiple ways; however, only optical, correlation-based techniques are able to deliver direct high-order and spatial results. In this paper two different optical metrologies are used for on-ground preparation and the actual execution of in-flight wing deformation measurements on a PW-6U glider. Firstly, the commercial PONTOS system is used for static tests on the ground and for wind tunnel investigations to successfully certify an experimental sensor pod mounted on top of the test bed fuselage. Secondly, a modification of the glider is necessary to implement the optical method named image pattern correlation technique (IPCT), which has been developed by the German Aerospace Center DLR. This scientific technology uses a stereoscopic camera set-up placed inside the experimental pod and a stochastic dot matrix applied to the area of interest on the glider wing to measure the deformation of the upper wing surface in-flight. The flight test installation, including the preparation, is described and results are presented briefly. Focussing on the compensation for typical error sources, the paper concludes with a recommended procedure to enhance the data processing for better results. Within the presented project IPCT has been developed and optimized for a new type of test bed. Adapted to the special requirements of the glider, the IPCT measurements were able to deliver a valuable wing deformation data base which now can be used to improve corresponding numerical models and simulations.

  16. Origin, Bulk Chemical Composition and Physical Structure of the Galilean Satellites of Jupiter: A Post-Galileo Analysis

    Science.gov (United States)

    Prentice, A. J. R.

    1999-01-01

    Callisto, NH3 ice makes up -5% of the condensate mass next to h-rock (approximately 50%) and H2O ice (approximately 45%). Detailed thermal and structural models for each of Europa, Ganymede and Callisto are constructed on the basis of the above initial bulk chemical compositions. For Europa (E), a predicted 2-zone model consisting of a dehydrated rock core of mass 0.912 M (sub E) and a 150 km thick frozen mantle of salty H2O yields a moment-of-inertia coefficient which matches the Galileo Orbiter gravity measurement. For Ganymede (G), a 3-zone model possessing an inner core of solid FeS and mass approximately 0.116 M (sub G), and an outer H2O ice mantle of mass approximately 0.502 M (sub G) is needed to explain the gravity data. Ganymede's native magnetic field was formed by thermoremanent magnetization of Fe3O4. A new Callisto (C) model is proposed consisting of a core of mass 0.826 M (sub C) containing a uniform mixture of h-rock (60% by mass) and H2O and NH3 ices, and capped by a mantle of pure ice. This model may have the capacity to yield a thin layer of liquid NH3 (raised dot) 2H2O at the core boundary, in line with Galileo's discovery of an induced magnetic field.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-08-28

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

  18. Formation of diapiric structure in the deformation zone, central Indian Ocean: A model from gravity and seismic reflection data

    Digital Repository Service at National Institute of Oceanography (India)

    Krishna, K.S.; Rao, D.G.; Neprochnov, Y.P.

    diapiric structure. 1. Introduction The events of uni cation of Indian and Australian plates in the middle Eocene (Liu et al 1983; Krishna et al 1995), hard continent-continent colli- sion to the north of the Indian shield (Curray et al 1982) and continuous... of the instability process reached the failure stage and triggered seis- mic activity in the middle of the Indo-Australian plate that deformed the upper lithosphere inten- sively (Weissel et al 1980). The activity's imprints are well documented in both the oceanic...

  19. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. A unified mathematical framework and an adaptive numerical method for fluid-structure interaction with rigid, deforming, and elastic bodies

    Science.gov (United States)

    Bhalla, Amneet Pal Singh; Bale, Rahul; Griffith, Boyce E.; Patankar, Neelesh A.

    2013-10-01

    Many problems of interest in biological fluid mechanics involve interactions between fluids and solids that require the coupled solution of momentum equations for both the fluid and the solid. In this work, we develop a mathematical framework and an adaptive numerical method for such fluid-structure interaction (FSI) problems in which the structure may be rigid, deforming, or elastic. We employ an immersed boundary (IB) formulation of the problem that permits us to avoid body conforming discretizations and to use fast Cartesian grid solvers. Rigidity and deformational kinematic constraints are imposed using a formulation based on distributed Lagrange multipliers, and a conventional IB method is used to describe the elasticity of the immersed body. We use Cartesian grid adaptive mesh refinement (AMR) to discretize the equations of motion and thereby obtain a solution methodology that efficiently captures thin boundary layers at fluid-solid interfaces as well as flow structures shed from such interfaces. This adaptive methodology is validated for several benchmark problems in two and three spatial dimensions. In addition, we use this scheme to simulate free swimming, including the maneuvering of a two-dimensional model eel and a three-dimensional model of the weakly electric black ghost knifefish.

  1. Improvement of the mathematical model of the diagram of deformation of the compressed composite steel and concrete structures

    Directory of Open Access Journals (Sweden)

    Fomin Stanislav

    2017-01-01

    Full Text Available The mathematical model of the stress-strain ratio of compressed concrete at elevated temperatures for composite structures described in Eurocode EN 1994-1-2:2005 Eurocode 4 divided in two stages: Stage 1 - represents the ascending branch and is defined by two parameters: compressive strength fc, θ and corresponding deformations εcu,θ, stage II - the descending branch which is accepted for numerical methods. The design practice showed deficiencies in the provisions on models of deformation diagrams given in Eurocode 2. Part 1-2 General provisions. Structural Fire Design. (EN 1992-1-2:2004, (ENV 1992-1-2:1995, which were reflected in the national standards in the process of harmonization. A technique for determining the refined diagrams “σc,θ – εc,θ” was developed for the design of composite reinforced concrete structures in case of fire. Diagram parameter values were adjusted for concretes based on silicate filler at high temperatures, the mathematical stress-strain model of the concrete under compression and high temperatures was specified.

  2. A thin FinFET Si-fin body structure fabricated with 193-nm scanner photolithography and composite hard mask etching technique upon bulk-Si substrate

    Science.gov (United States)

    Liao, Wen-Shiang; Liu, Yu-Huan; Chang, Wen-Tung; Chen, Tung-Hung; Shih, Tommy; Tsen, Huan-Chiu; Chung, Lee

    2007-03-01

    A thin FinFET bulk Si-fin body structure has been successfully fabricated upon bulk-Si wafers through using 193nm scanner lithography and a composite hard mask etching technique. First, a 100Å-thick buffer SiO II layer was thermally grown upon the bulk silicon layer and subsequently a 1200Å-thick SiN x layer and a 1000Å-thick TEOS SiO II hard mask layer was chemically vapor deposited to form a composite hard mask structure of buffer-SiO II/SiN x/TEOS. Second, both 1050Å-thick BARC and 2650Å-thick photoresist (P/R) were coated and a 193nm scanner lithography tool was used for the Si-fin body layout patterning under relatively high exposure energy. This achieves the ADI (after develop inspection) of 80nm from the original as-drawn Si-fin layout of 110nm. Then, a deep sub-micron plasma etcher was used for an aggressive P/R and BARC trimming down processing and both the capping TEOS and CVD-SiN x with its underlying buffer oxide layers were subsequently etched in other etching plasma chambers, respectively. Resultantly, the AMI (after mask inspection) can reach 60nm. Subsequently, both the P/R and BARC were removed with a nominal plasma ashing as well as a RCA cleaning for the final sub-micron Si-fin plasma etching. Eventually, a 60nm-width and 400nm-height bulk Si-fin body structure can be successfully etched out after a fixed time-mode silicon plasma etching.

  3. 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.

  4. Field Investigation of Surface Deformation Induced by the 2016 Meinong Earthquake and its Implications to Regional Geological Structures

    Science.gov (United States)

    Yi, De-Cheng; Chuang, Ray Y.; Lin, Ching-Weei

    2017-04-01

    We demonstrate mapping results of a newly-identified active folding-associated fault in southwestern Taiwan, which was triggered by the distant ML 6.6 Meinong earthquake in 2016. The 14.6-km-deep main shock occurred in Meinong at 3:57 (GMT +08) on February 6th while a series of 21-27 km deep aftershocks were induced after 160 seconds in Guanmiao, where is 25km NW away from the epicenter of the main shock. The focal mechanism of the Meinong main shock shows a westward oblique thrust with the fault plane of 275°/42°/17° (strike/dip/rake) but Guanmiao aftershocks show the N-S striking eastward normal movement. The study area locates at an on-going fold-and-thrust belt close to the deformation front of Taiwan orogeny with high rates of convergence, uplift and erosion. The geology of SW Taiwan is characterized by the 3-km-thick mudstones with high fluid pressure underlying the loose sedimentary rocks forming mud diapirs or mud-core anticlines. The significance of the Meinong earthquake is (1) aftershocks are far away from the main shock, and (2) the surface cracks partially distributed systematically along lineaments observed from InSAR, which has never been recognized as geological structures before. This study aims to establish possible kinematic processes of shallow deformation induced by the Meinong earthquake. We mapped surface cracks around the lineaments by using hand-held GPS and measured surface cracks by the compass and vernier. Among 249 kinematic data measured from 244 observed surface cracks and ruptures, the type of deformation was mostly identified as dilation or lateral translation and only 4 data were compressional deformation. The overall surface displacement moved to the northwest and west, consistent with the regional coseismic movement. The opening of the surface cracks range from 0.5 to 105 mm and 85% of them are less than 10 mm. Preseismic deformed features such as failure of the retaining wall were also observed along the western and eastern

  5. 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

  6. Modified suture-bridge technique to prevent a marginal dog-ear deformity improves structural integrity after rotator cuff repair.

    Science.gov (United States)

    Ryu, Keun Jung; Kim, Bang Hyun; Lee, Yohan; Lee, Yoon Seok; Kim, Jae Hwa

    2015-03-01

    The arthroscopic suture-bridge technique has proved to provide biomechanically firm fixation of the torn rotator cuff to the tuberosity by increasing the footprint contact area and pressure. However, a marginal dog-ear deformity is encountered not infrequently when this technique is used, impeding full restoration of the torn cuff. To evaluate the structural and functional outcomes of the use of a modified suture-bridge technique to prevent a marginal dog-ear deformity compared with a conventional suture-bridge method in rotator cuff repair. Cohort study; Level of evidence 2. A consecutive series of 71 patients aged 50 to 65 years who underwent arthroscopic rotator cuff repair for full-thickness medium-sized to massive tears was evaluated. Patients were divided into 2 groups according to repair technique: a conventional suture-bridge technique (34 patients; group A) versus a modified suture-bridge technique to prevent a marginal dog-ear deformity (37 patients; group B). Radiographic evaluations included postoperative cuff integrity using MRI. Functional evaluations included pre- and postoperative range of motion (ROM), pain visual analog scale (VAS), the University of California, Los Angeles (UCLA) shoulder rating scale, the Constant score, and the American Shoulder and Elbow Surgeons (ASES) score. All patients were followed up clinically at a minimum of 1 year. When the 2 surgical techniques were compared, postoperative structural integrity by Sugaya classification showed the distribution of types I:II:III:IV:V to be 4:20:2:4:4 in group A and 20:12:4:0:1 in group B. More subjects in group B had a favorable Sugaya type compared with group A (P bridge technique repairs were found in the retear group (P = .03). There were significant differences between healed and retear groups in functional outcome scores, with worse results in the retear group. A modified suture-bridge technique to prevent a marginal dog-ear deformity provided better structural outcomes than a

  7. 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.

  8. Composites based on cellulose fiber nonwovens and a water soluble polymer 1. Structure and strength-deformation characteristics of cellulose fiber nonwovens and structural characteristics of the composites

    Science.gov (United States)

    Cerpakovska, D.; Kalnins, M.

    2012-03-01

    The results of a study on the strength-deformation characteristics (tensile elastic modulus, ultimate strength, elongation at break, and punching and tearing strengths) of two kinds of cellulose fiber nonwovens (CFNs) with dissimilar void content and different geometrical parameters of cellulose fibers are discussed. The structural characteristics of composites prepared by impregnation with poly(vinyl alcohol) water solutions are analyzed, too. Composites with volume fractions of polymer up to 0.4% and volume fractions of voids up to 0.3% were prepared. Filling of voids by the polymer occurred without significant changes in the structure of CFNs. The fraction of closed voids increased with polymer content.

  9. Characterization of myofibrils cold structural deformation degrees of frozen pork using hyperspectral imaging coupled with spectral angle mapping algorithm.

    Science.gov (United States)

    Cheng, Weiwei; Sun, Da-Wen; Pu, Hongbin; Wei, Qingyi

    2018-01-15

    The study investigated the possibility of using hyperspectral imaging (HSI) in the spectral range of 1000-2200nm to characterize myofibrils cold structural deformation degrees of frozen pork samples. The HSI images of pork samples frozen under different freezing rates were acquired in the frozen state without thawing. The myofibrils cold structural deformation degrees were evaluated by surface hydrophobicity (S0ANS) and Ca(2+)-ATPase activity. Spectral angle mapping (SAM) algorithm was used for the first time to extract the spectral information for regression. Compared with the optimized partial least square regression (PLSR) models based on selected wavebands by successive projections algorithm (SPA), the optimized PLSR models developed based on the spectral angles calculated by the SAM algorithm achieved comparable or even better performance with R(2)P of 0.896 for S0ANS and 0.879 for Ca(2+)-ATPase activity, respectively. The implications of the frozen meat spectrum were also analyzed in the current study. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Microstructural characteristics of nano-structured Fe-28.5Ni steel by means of severe plastic deformation

    Science.gov (United States)

    Mousavi Anijdan, S. H.; Jafarian, H. R.; Bahrami, A.

    2017-05-01

    Microstructural evolution together with changes in mechanical properties of an high nickel content steel processed by various cycles of accumulative roll bonding (ARB) is explored. It is shown by Electron Backscatter Diffraction (EBSD) analysis that after successive roll bonding processes a stabilized nano-structure is developed containing sufficient amount of ductility under severe plastic deformation. A mean grain size of few hundred nano meter was obtained after 6-cycle of ARB process meaning that the successive ARB cycles made the structure quite refined. The starting material was mainly coming from the transformation of martensite to retained austenite, particularly under high temperature and in high cycle of ARB process. This is an early indication of the stabilization of retained austenite during the ARB process through grain refinement phenomenon. Uniaxial tensile test demonstrated that yield strength significantly improves by only one cycle of ARB process. Successive cycles of ARB process gradually increased the yield and the ultimate tensile strengths at the expense of ductility. The main cause of such a substantial increase in yield strength is discussed. Remarkably high amount of ductility was still observed in a very high amount of deformation that was applied in the 6-cycle ARB process.

  11. Hydrostatic and shear behavior of frictionless granular assemblies under different deformation conditions

    NARCIS (Netherlands)

    Imole, Olukayode Isaiah; Kumar, Nishant; Magnanimo, Vanessa; Luding, Stefan

    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

  12. 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

    2013-01-01

    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

  13. 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

  14. 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...... 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. As a result...

  15. Micro-beam and pulsed laser beam techniques for the micro-fabrication of diamond surface and bulk structures

    Energy Technology Data Exchange (ETDEWEB)

    Sciortino, S. [Dipartimento di Fisica e Astronomia, Università di Firenze, Via Sansone 1, I-50019 Sesto Fiorentino, Firenze (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Firenze, Via Sansone 1, I-50019 Sesto Fiorentino, Firenze (Italy); Bellini, M. [European Laboratory for Non-Linear Spectroscopy, Via Nello Carrara 1, 50019 Sesto Fiorentino (Italy); Istituto Nazionale di Ottica (INO-CNR), Largo Enrico Fermi 6, 50125 Firenze (Italy); Bosia, F. [Physics Department and “Nanostructured Interfaces and Surfaces” Inter-departmental Centre, University of Torino, via P. Giuria 1, 10125 Torino (Italy); INFN Sezione di Torino, via P. Giuria 1, 10125 Torino (Italy); Calusi, S. [Dipartimento di Fisica e Astronomia, Università di Firenze, Via Sansone 1, I-50019 Sesto Fiorentino, Firenze (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Firenze, Via Sansone 1, I-50019 Sesto Fiorentino, Firenze (Italy); Corsi, C. [Dipartimento di Fisica e Astronomia, Università di Firenze, Via Sansone 1, I-50019 Sesto Fiorentino, Firenze (Italy); European Laboratory for Non-Linear Spectroscopy, Via Nello Carrara 1, 50019 Sesto Fiorentino (Italy); Czelusniak, C. [Dipartimento di Fisica e Astronomia, Università di Firenze, Via Sansone 1, I-50019 Sesto Fiorentino, Firenze (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Firenze, Via Sansone 1, I-50019 Sesto Fiorentino, Firenze (Italy); Gelli, N. [Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Firenze, Via Sansone 1, I-50019 Sesto Fiorentino, Firenze (Italy); and others

    2015-04-01

    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.

  16. Structural Kinematics of Two Regional Transects Across the Manila Trench Offshore Southern Taiwan: Untangling Thick from Thin Skin Deformation

    Science.gov (United States)

    Bernal-Olaya, R.; Chi, W. C.; Kunath, P.; McIntosh, K. D.

    2016-12-01

    Recent research offshore Southern Taiwan has proposed that a hyper-extended continental crust is involved in the convergent margin of the Manila trench as far south as 20°N (Lester et al., 2013; McIntosh et al., 2013; and Eakin et al., 2014). If and how such pre-existing structures affect modern deformation styles is still unclear. Here, we combine large offset seismic reflection profiles, gravity anomaly, and seismicity data to study two transects. Preliminary analyses of Bouguer gravity data and focal mechanisms are consistent with the proposed hyper-extended model. Observations suggest two major crustal lineament trends: 1. A NE-SW steep gravity gradient trend west of Taiwan that correlates with the passive margin normal faults as defined by Lin et al., 2003; 2. A NW-SE regional lineament that correlates with deep seismicity (>30km) offshore SW Taiwan (Wu et al., 2009) and is orthogonal to the normal fault trend. Preliminary gravity analyses also suggest southward deepening of the top of the basement from the Central Range, to the Hengchun Peninsula, to its offshore continuation. By integrating gravity and earthquake data with the structural interpretation of two 2D EW-trending regional seismic sections at 20oN and 22oN, we describe the geometry, and propose a kinematic history of the prowedge. Results display contrasting widths and taper angles between both sections. To the north, the wedge is wide ( 95km) and less steep (α+β= 6ͦ) than to the south. In contrast, the wedge to the south is narrower ( 65km) and steeper (α+β= 13ͦ). We interpret that differences in coulomb wedge behavior from north to south are due to the presence of inherited crustal structures and to the effect of the initial stages of collision. Inherited structures accommodate very thick sedimentary deposition and also accommodate deformation by buttressing younger structures. These characteristics make the Manila accretionary prism a unique example of ongoing basement-involved-deformation

  17. Parity shift and beat staggering structure of octupole bands in a collective model for quadrupole-octupole-deformed nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Minkov, N [Institute of Nuclear Research and Nuclear Energy, 72 Tzarigrad Road, Sofia 1784 (Bulgaria); Yotov, P [Institute of Nuclear Research and Nuclear Energy, 72 Tzarigrad Road, Sofia 1784 (Bulgaria); Drenska, S [Institute of Nuclear Research and Nuclear Energy, 72 Tzarigrad Road, Sofia 1784 (Bulgaria); Scheid, W [Institut fuer Theoretische Physik der Justus-Liebig-Universitaet, Heinrich-Buff-Ring 16, D-35392 Giessen (Germany)

    2006-04-01

    We propose a collective model formalism which describes the strong parity shift observed in low-lying spectra of nuclei with octupole deformations together with the fine rotational band structure developed at higher-angular momenta. The parity effect is obtained by the Schroedinger equation for oscillations of the reflection asymmetric (octupole) shape between two opposite orientations in an angular momentum dependent double-well potential. The rotational structure is obtained by a collective quadrupole-octupole rotation Hamiltonian. The model scheme reproduces the complicated beat staggering patterns observed in the octupole bands of light actinide nuclei. It explains the angular momentum evolution of octupole spectra as the interplay between the octupole shape oscillation (parity shift) mode and the stable quadrupole-octupole rotation mode.

  18. The structural fabric and deformation history of a mountain logjam: cameras, creep, and catastrophe

    Science.gov (United States)

    Deshpande, N.; Crosby, B. T.

    2016-12-01

    Wood and sediment are integral agents in the river transport processes that facilitate the chemical and physical evolution of landscapes. As such, the two pose an almost poetic contrast to each other: wood is buoyant, organic and elongate while sediment is dead, dense, and round. Despite wide recognition of the value of wood to river corridors, our mechanistic understanding of logjam kinematics and mobility is limited. This is in part due to historic logging practices that alter forests and `natural' river-wood feedbacks as well as contemporary attitudes that regard logjams as a nuisance. Both severely limit our ability to observe logjams in the field. Existing physically-based rules for wood transport are insufficient for this task at hand; a simple force balance approach quickly breaks down in the face of the complexity of the underlying kinematic fabric. Here, we present the results of a yearlong survey of an actively deforming logjam in the Salmon River Mountains, central Idaho. We use interval photography, pressure transducer/water level loggers and total station measurements of 150 logs within the jam (about 10% of the total population), to document where and when logjams move. The mean cumulative magnitude of displacement during the high-flow period is 2.06 m +/- 1.51 m, much of which occurred during a single event. Smaller magnitude creeping movement also occurs as the jam experiences cyclic quasi-diel fluctuations in stage due to snowmelt-generated discharge. Our results highlight the interplay between horizontal drag forces and vertical buoyant forces in governing the network of frictional connections and subsequent deformation within the logjam.

  19. Tooth axis and skeletal structures in mandibular molar vertical sections in jaw deformity with facial asymmetry using MPR images.

    Science.gov (United States)

    Nojima, Kunihiko; Yokose, Taishi; Ishii, Takenobu; Kobayashi, Makoto; Nishii, Yasushi

    2007-11-01

    The objective of the present study was to investigate frontal morphological asymmetry in the mandibular molar region in terms of tooth axis and skeletal structures using vertical MPR sections in jaw deformity accompanied by facial asymmetry. Subjects consisted of 15 patients with jaw deformity accompanied by facial asymmetry aged 17.4 years to 37.8 years. There were four men and eleven women. Based on X-ray computed tomography (CT) scans, DICOM viewer software was used to prepare multiplanar reconstruction (MPR) sections. The mandible was then positioned on a reference plane based on the menton and left and right gonions, and a vertical MPR section passing through the mesial root of the first mandibular molar was prepared. The following measurements were made on both the shifted and non-shifted sides: maximum buccolingual width of the mandibular body; height of the mandibular body; inclination angle of the mandibular body; degree of buccal protrusion of the mandibular body; and inclination angle of the buccolingual tooth axis of the first molar. Furthermore, degree of median deviation in the menton was measured using frontal cephalograms. Differences in morphological parameters between the shifted and non-shifted sides were assessed. Furthermore, the relationship between median deviation and asymmetry were statistically analyzed. There was no significant asymmetry in the maximum buccolingual width of the mandibular body, the height of the mandibular body or the degree of buccal protrusion of the mandibular body. However, when compared to the shifted side, the inclination angle of the buccolingual tooth axis of the first molar for the non-shifted side was significantly greater. There was a relatively strong correlation between median deviation and inclination angle of the mandibular body. The above findings clarified that, in orthognathic surgery for jaw deformity accompanied by facial asymmetry, actively improving asymmetry in the buccolingual inclination of the

  20. Effect of Structural Heterogeneity of 17Mn1Si Steel on the Temperature Dependence of Impact Deformation and Fracture

    Directory of Open Access Journals (Sweden)

    Dmitry Moiseenko

    2017-07-01

    Full Text Available The paper deals with a theoretical and experimental study of the relationship between the microstructural parameters, mechanical properties, and impact deformation and fracture of steels using the example of 17Mn1Si pipe steel. A model for the behavior of a polycrystalline grain conglomerate under impact loading at different temperatures was proposed within a cellular automata framework. It was shown that the intensity of dissipation processes explicitly depends on temperature and these processes play an important role in stress relaxation at the boundaries of structural elements. The Experimental study reveals the relationship between pendulum impact test temperature and the deformation/fracture energy of the steel. The impact toughness was shown to decrease almost linearly with the decreasing test temperature, which agrees with the fractographic analysis data confirming the increase in the fraction of brittle fracture in this case. It was shown with the aid of the proposed model and numerical simulations that the use of the excitable cellular automata method and an explicit account of test temperature through the possibility of energy release at internal interfaces help to explain the experimentally observed features of impact failure at different temperatures.

  1. 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).

  2. Basal Complex and Basal Venation of Odonata Wings: Structural Diversity and Potential Role in the Wing Deformation.

    Directory of Open Access Journals (Sweden)

    H Rajabi

    Full Text Available 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.

  3. Structural origin of set-reset process in a new bulk Si15Te83Ge2 phase-change memory material

    Directory of Open Access Journals (Sweden)

    Srinivasa Rao Gunti

    2011-03-01

    Full Text Available A new phase-change memory material, in bulk, has been prepared by melt-quenching technique, which has a better glass forming ability. This sample is set and resettable relatively easily for several cycles at 2mA SET and RESET input currents, and is likely to be a suitable material for phase-change memory applications. Raman scattering studies have been undertaken during the SET and RESET operations to elucidate the local structural transformations that occur during these operations.

  4. Constraining the Late Mesozoic and Early Tertiary Tectonic Evolution of Southern Mexico: Structure and Deformation History of the Tierra Caliente Region.

    Science.gov (United States)

    Cabral-Cano; Draper; Lang; Harrison

    2000-07-01

    We analyze the structure and assess the deformation history of the Tierra Caliente Metamorphic Complex (TCMC) of southern Mexico, where Laramide accretion of exotic terranes is in debate. The TCMC consists of a south-plunging antiform fault that is bounded on both its eastern and western flanks. Tierra Caliente Metamorphic Complex rocks show at least two phases of compressional deformation. The first and most prominent records a mean tectonic transport direction of 068 degrees. This phase is responsible for east-verging asymmetrical folding and thrusting of both metamorphic and superjacent sedimentary rocks. The second phase has an average transport direction of 232 degrees and is restricted to the western portion of the TCMC. A third phase is responsible for normal faulting. Lack of discernible deformation before Late Cretaceous time indicates that the main deformation phase is coincident with Laramide orogenesis elsewhere in the North American Cordillera. The stratigraphy, structure, and deformational history of the TCMC do not require accretion of exotic terranes. We explain the Mesozoic tectonostratigraphic evolution of the TCMC in terms of deposition and deformation of Mesozoic volcanic and sedimentary strata over the attenuated continental crust of the North American plate.

  5. 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.

  6. Update of the equations of the limit state of the structural material with the realization of their deformation

    Science.gov (United States)

    Zenkov, E. V.

    2018-01-01

    Two methods are given in the article by considering the type of stressed-Deformed state (SDS) based on equations limit condition and analyzing the results of laboratory tests of special specimens for mechanical testing, focus having destruction thereof in the same view of SDS as in focus possible destruction of the structural member. The considered limited use of these methods in terms of considering physically consistent strength criterion type Pisarenko-Lebedev. A revised design-experimental procedure for determining the strength of the material of the structure, combining therein the elements of these two methods, consisting in determining the strength parameters of construction material, entering criterion equation Pisarenko-Lebedev, considering the actual appearance of the region-of-interest SDS structure. The implementation of the procedure is performed on the basis of the selection of the respective experimental laboratory specimens for mechanical testing, plan SDS in working zone coinciding with a SDS: structure whose strength is evaluated. The refinement process limit state equations demonstrated in determining 50CrV4 steel strength parameters, being in a state of biaxial stretching. Design-experimentally determined by, that steel for a given voltage limit value is almost a quarter of its value is reduced compared to the conventional tensile strength. value is reduced compared to the conventional tensile strength.

  7. Micro-structure and chemical composition of vateritic deformities occurring in the bivalve Corbicula fluminea (Müller, 1774).

    Science.gov (United States)

    Frenzel, Max; Harper, Elizabeth M

    2011-05-01

    Vateritic deformities occurring in the invasive heterodont bivalve Corbicula fluminea from several locations in the UK were characterised in detail for the first time using scanning electron microscopy, X-ray diffraction and different geochemical techniques (electron microprobe, ICP-AES, and mass spectrometry). Large volumes of vaterite are produced abnormally in the animals' shells in the form of yellow-green bulges. These are distinguished from the aragonitic parts of the shell by their characteristic micro-structures, content of organic material, trace elemental composition and carbon stable isotope signatures. The most commonly observed micro-structures include columnar vaterite, lamellar vaterite and different irregular structures occurring in all parts of the shell. There are indications that organic material is present largely as intracrystalline impurities or nano-scale phases and not as envelopes around microstructural units. These micro-structures are novel, nothing equivalent having yet been described for other vateritic systems. Euhedral vaterite crystals also occur occasionally. The vaterite has generally higher Mg/Ca and lower Na/Ca, K/Ca than the aragonite. In addition, δ¹³C is also always lower. Microstructural characteristics would suggest loss of biological control probably due to physiological stress(es) inducing the switch to vaterite production. The vaterite might be stabilised by its higher content of organic material and magnesium. Copyright © 2011 Elsevier Inc. All rights reserved.

  8. STRUCTURAL INTERACTIONS OF HYDROGEN WITH BULK AMORPHOUS MICROSTRUCTURES IN METALLIC SYSTEMS UNDERSTANDING THE ROLE OF PARTIAL CRYSTALLINITY ON PERMEATION AND EMBRITTLEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Brinkman, Kyle; Fox, Elise; Korinko, Paul; Adams, Thad

    2010-05-10

    The development of metallic glasses in bulk form has led to a resurgence of interest into the utilization of these materials for a variety of applications. A potentially exciting application for these bulk metallic glass (BMG) materials is their use as composite membranes to replace high cost Pd/Pd-alloy membranes for enhanced gas separation processes. One of the major drawbacks to the industrial use of Pd/Pd-alloy membranes is that during cycling above and below a critical temperature an irreversible change takes place in the palladium lattice structure which can result in significant damage to the membrane. Furthermore, the cost associated with Pd-based membranes is a potential detractor for their continued use and BMG alloys offer a potentially attractive alternative. Several BMG alloys have been shown to possess high permeation rates, comparable to those measured for pure Pd metal. In addition, high strength and toughness when either in-situ or ex-situ second phase dispersoids are present. Both of these properties, high permeation and high strength/toughness, potentially make these materials attractive for gas separation membranes that could resist hydrogen 'embrittlement'. However, a fundamental understanding of the relationship between partially crystalline 'structure'/devitrification and permeation/embrittlement in these BMG materials is required in order to determine the operating window for separation membranes and provide additional input to the material synthesis community for improved alloy design. This project aims to fill the knowledge gap regarding the impact of crystallization on the permeation properties of metallic glass materials. The objectives of this study are to (i) determine the crystallization behavior in different gas environments of Fe and Zr based commercially available bulk metallic glass and (ii) quantify the effects of partial crystallinity on the hydrogen permeation properties of these metallic glass membranes.

  9. 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.

  10. Distributed deformation structures in shallow water carbonates subsiding through a simple stress field (Jandaira Formation, NE Brazil)

    Science.gov (United States)

    Bertotti, Giovanni; Bisdom, Kevin; Bezerra, Hilario; Reijmer, John; Cazarin, Carol

    2016-04-01

    Despite the scarcity of major deformation structures such as folds and faults, the flat-lying, post-rift shallow water carbonates of the Jandaira Formation (Potiguar Basin, NE Brazil) display well-organized fracture systems distributed of tens of km2. Structures observed in the outcropping carbonates are sub-vertical, generally N-S trending mode I and hybrid veins and barren fractures, sub-vertical roughly E-W trending stylolites and sub-horizontal stylolites. These features developed during subsidence in a simple and constant stress field characterized by, beside gravity, a significant horizontal stress probably of tectonic origin. The corresponding depth curves have different origin and slopes and, therefore, cross each other resulting in position of the principal stresses which change with depth. As a result, the type and amount of fractures affecting subsiding rocks change despite the fact that the far-field stresses remain constant. Following early diagenesis and porosity elimination in the first 100-200m depth, Jandaira carbonates experienced wholesale fracturing at depths of 400-800m resulting in a network of NNW-NE trending fractures partly organized in conjugate sets with a low interfault angle and a sub-vertical intersection, and sub-vertical stylolites roughly perpendicular to the fractures. Intense fluid circulation was activated as a consequence through the carbonates. With increasing subsidence, sub-horizontal stylolites formed providing calcite which precipitated in the open fractures transforming them in veins. The Jandaira formation lost thereby the permeability it had reached during the previous stage. Because of the lack of major deformation, the outcrops of the Jandaira Formation is an excellent analog for carbonate reservoirs in the Middle East, South Atlantic and elsewhere.

  11. Global case studies of soft-sediment deformation structures (SSDS: Definitions, classifications, advances, origins, and problems

    Directory of Open Access Journals (Sweden)

    G. Shanmugam

    2017-10-01

    Problems that hinder our understanding of SSDS still remain. They are: (1 vague definitions of the phrase “soft-sediment deformation”; (2 complex factors that govern the origin of SSDS; (3 omission of vital empirical data in documenting vertical changes in facies using measured sedimentological logs; (4 difficulties in distinguishing depositional processes from tectonic events; (5 a model-driven interpretation of SSDS (i.e., earthquake being the singular cause; (6 routine application of the genetic term “seismites” to the “SSDS”, thus undermining the basic tenet of process sedimentology (i.e., separation of interpretation from observation; (7 the absence of objective criteria to differentiate 21 triggering mechanisms of liquefaction and related SSDS; (8 application of the process concept “high-density turbidity currents”, a process that has never been documented in modern oceans; (9 application of the process concept “sediment creep” with a velocity connotation that cannot be inferred from the ancient record; (10 classification of pockmarks, which are hollow spaces (i.e., without sediments as SSDS, with their problematic origins by fluid expulsion, sediment degassing, fish activity, etc.; (11 application of the Earth's climate-change model; and most importantly, (12 an arbitrary distinction between depositional process and sediment deformation. Despite a profusion of literature on SSDS, our understanding of their origin remains muddled. A solution to the chronic SSDS problem is to utilize the robust core dataset from scientific drilling at sea (DSDP/ODP/IODP with a constrained definition of SSDS.

  12. Deformation patterns in a high-viscosity lava flow inferred from the crystal preferred orientation and imbrication structures: an example from Salina (Aeolian Islands, southern Tyrrhenian Sea, Italy)

    Science.gov (United States)

    Ventura, Guido; Rosa, Rosanna De; Colletta, Elena; Mazzuoli, Roberto

    1996-04-01

    Shape-preferred orientation and imbrication structures of crystals have been measured on samples representative of the base, centre and top of a highly viscous lava flow on Salina (Aeolian Islands, southern Tyrrhenian Sea). The data allow zones with different deformation patterns to be identified. In the base and top of the flow, deformation leads to the development of discrete preferred orientation and imbrication of the elongate crystals. The sense of shear is right-lateral at the base and left-lateral at the top of the flow. Shear strain can be estimated by the analysis of crystal preferred orientation. Deformation increases from the flow centre to the outer, more viscous boundary layers. Random orientation of crystals in the inner zone supports the presence of plug flow in a pseudoplastic lava. The textural features of the studied lava may be related to different mechanisms (i.e. lateral expansion). We conclude that the observed crystal alignments and imbrication structures may be related to a plug flow moving between two non-deforming walls. The walls are represented by the solidified, broken upper and basal crust of the flow. The low shear strain values calculated in the outer margins of the flow are indicative of the last deformation event. Crystal preferred orientation and imbrication structures may be related to the occurrence of velocity gradients existing between the inner zone of the flow and its solidus or near-solidus outer margins.

  13. Tris(triazolyl)borate ligands of intermediate steric bulk for the synthesis of biomimetic structures with hydrogen bonding and solubility in hydrophilic solvents.

    Science.gov (United States)

    Gardner, Sean R; Papish, Elizabeth T; Monillas, Wesley H; Yap, Glenn P A

    2008-12-01

    Tris(triazolyl)borate ligands (Ttz) of intermediate steric bulk were synthesized to investigate their potential for hydrogen bonding and improved solubility in hydrophilic solvents as applied to biomimetic chemistry. The crystal structure of 3-phenyl-5-methyl-1,2,4-triazole (Htz(Ph,Me)) revealed hydrogen bonding and pi stacking interactions. The new ligand salt, potassium tris(3-phenyl-5-methyl-1,2,4-triazolyl)borate (KTtz(Ph,Me)) was synthesized as the first example of a Ttz ligand of intermediate steric bulk. Metathesis between KTtz(Ph,Me) and NaCl followed by recrystallization produced [NaTtz(Ph,Me)].6CH3OH in which the geometry around the sodium is octahedral with an unusual N(3)O(3) donor set; this structure also shows that a hydrogen bonding network is formed by methanol molecules and triazole nitrogens. (Ttz(Ph,Me))ZnCl was synthesized and characterized crystallographically as [(Ttz(Ph,Me))ZnCl].0.5CH3OH in which the zinc is tetrahedral and the triazole rings are within hydrogen bonding distance of CH(3)OH. All of these new compounds are methanol soluble to varying degrees and Htz(Ph,Me) and KTtz(Ph,Me) are soluble in methanol/water mixtures.

  14. Deformation of Sedimentary Rock Across the San Andreas Fault Zone: Mesoscale and Microscale Structures Displayed in Core From SAFOD

    Science.gov (United States)

    Chester, J. S.; Chester, F. M.; Kirschner, D. L.; Almeida, R.; Evans, J. P.; Guillemette, R. N.; Hickman, S.; Zoback, M.; Ellsworth, W.

    2007-12-01

    Sedimentary rocks captured in cores taken at the San Andreas Fault Observatory at Depth (SAFOD) provide an unparalleled sampling of deformation in the transition zone between creeping and locked segments of a major transform fault at 2.5-3.1 km vertical depth. These samples provide the unique opportunity to study deformation processes and the development of brittle structures within porous and granular rocks that have been subjected to variable loading rates and chemically reactive fluids while residing at the top of the seismogenic zone. The samples provide a transect from relatively undeformed host rock through highly fractured and sheared rock, and capture the two prominent zones of active, aseismic slip. Core recovery was almost complete. Wrap-around 1:1 map tracings of the outer surfaces of all cores characterize the lithology and mesoscale deformation. Cores from 3056-3067 m and 3141-3153 m measured depth (MD) sample moderately deformed rock at the western boundary of the fault zone. The cores display massive to finely laminated, pebbly arkosic sandstones with lesser amounts of fine-grained sandstone and siltstone. Numerous shear fractures and cm-thick cataclastic shear zones form a conjugate geometry indicating contraction at high angles to the San Andreas fault. Both intervals display minor faults that juxtapose different lithologies consistent with meters or greater of slip. Fracture density is variable but tends to increase with proximity to the minor faults. Cross-cutting relationships between shear fractures and cataclastic zones indicate a general progression from early faulting along thicker shear zones to later, more localized slip within shear zones and along fractures. Microstructures provide ample evidence for densification of the sandstones through grain-scale fracture and crushing, as well as fluid assisted processes of crack-sealing, dissolution-precipitation, and alteration-neocrystallization. Grain-scale features are consistent with these

  15. Cobalt Phthalocyanine Modified Electrodes Utilised in Electroanalysis: Nano-Structured Modified Electrodes vs. Bulk Modified Screen-Printed Electrodes

    Directory of Open Access Journals (Sweden)

    Christopher W. Foster

    2014-11-01

    Full Text Available Cobalt phthalocyanine (CoPC compounds have been reported to provide electrocatalytic performances towards a substantial number of analytes. In these configurations, electrodes are typically constructed via drop casting the CoPC onto a supporting electrode substrate, while in other cases the CoPC complex is incorporated within the ink of a screen-printed sensor, providing a one-shot economical and disposable electrode configuration. In this paper we critically compare CoPC modified electrodes prepared by drop casting CoPC nanoparticles (nano-CoPC onto a range of carbon based electrode substrates with that of CoPC bulk modified screen-printed electrodes in the sensing of the model analytes L-ascorbic acid, oxygen and hydrazine. It is found that no “electrocatalysis” is observed towards L-ascorbic acid using either of these CoPC modified electrode configurations and that the bare underlying carbon electrode is the origin of the obtained voltammetric signal, which gives rise to useful electroanalytical signatures, providing new insights into literature reports where “electrocatalysis” has been reported with no clear control experiments undertaken. On the other hand true electrocatalysis is observed towards hydrazine, where no such voltammetric features are witnessed on the bare underlying electrode substrate.

  16. Combatting bulking sludge with ultrasound

    Energy Technology Data Exchange (ETDEWEB)

    Wuensch, B.; Heine, W.; Neis, U. [Technische Univ. Hamburg-Harburg, Hamburg (Germany). Dept. of Sanitary and Environmental Engineering

    2002-07-01

    Bulking and floating sludge cause great problems in many waste water treatment plants with biological nutrient removal. The purification as well as the sludge digestion process can be affected. These problems are due to the interlaced structure of filamentous microorganisms, which have an impact on the sludge's settling behaviour. Foam is able to build up a stable layer, which does not settle in the secondary clarifier. Foam in digestion causes a reduction of the degree of stabilisation and of the biogas production. We use low-frequency ultrasound to combat filamentous organisms in bulking sludge. Low-frequency ultrasound is suitable to create high local shear stresses, which are capable of breaking the filamentous structures of the sludge. After preliminary lab-scale tests now a full-scale new ultrasound equipment is operating at Reinfeld sewage treatment plant, Germany. The objective of this study is to explore the best ultrasound configuration to destroy the filamentous structure of bulking and foaming sludge in a substainable way. Later this study will also look into the effects of ultrasound treated bulking sludge on the anaerobic digestion process. Up to now results show that the settling behaviour of bulking sludge is improved. The minimal ultrasound energy input for destruction of bulking structure was determined. (orig.)

  17. UTILIZATION OF STEREOLOGY FOR QUANTITATIVE ANALYSIS OF PLASTIC DEFORMATION OF FORMING PIECES

    Directory of Open Access Journals (Sweden)

    Maroš Martinkovič

    2012-01-01

    Full Text Available Mechanical working leads to final properties of forming pieces, which are affected by conditions of production technology. Utilization of stereology leads to the detail analysis of three-dimensional plastic deformed material structure by different forming technologies, e.g. forging, extruding, upsetting, metal spinning, drawing etc. The microstructure of cold drawing wires was analyzed. Grain boundaries orientation was measured on the parallel section of wire with a different degree of deformation and direct axis plastic deformation was evaluated in bulk formed part. The strain of probes on their sections was obtained using stereology by measurement of degree of grain boundary orientation which was converted to deformation using model of conversion of grain boundary orientation degree to deformation.

  18. Variable-Domain Displacement Transfer Functions for Converting Surface Strains into Deflections for Structural Deformed Shape Predictions

    Science.gov (United States)

    Ko, William L.; Fleischer, Van Tran

    2015-01-01

    Variable-Domain Displacement Transfer Functions were formulated for shape predictions of complex wing structures, for which surface strain-sensing stations must be properly distributed to avoid jointed junctures, and must be increased in the high strain gradient region. Each embedded beam (depth-wise cross section of structure along a surface strain-sensing line) was discretized into small variable domains. Thus, the surface strain distribution can be described with a piecewise linear or a piecewise nonlinear function. Through discretization, the embedded beam curvature equation can be piece-wisely integrated to obtain the Variable-Domain Displacement Transfer Functions (for each embedded beam), which are expressed in terms of geometrical parameters of the embedded beam and the surface strains along the strain-sensing line. By inputting the surface strain data into the Displacement Transfer Functions, slopes and deflections along each embedded beam can be calculated for mapping out overall structural deformed shapes. A long tapered cantilever tubular beam was chosen for shape prediction analysis. The input surface strains were analytically generated from finite-element analysis. The shape prediction accuracies of the Variable- Domain Displacement Transfer Functions were then determined in light of the finite-element generated slopes and deflections, and were fofound to be comparable to the accuracies of the constant-domain Displacement Transfer Functions

  19. Kinematics of an oblique deformation front using paleomagnetic data; the Altomira-Loranca structures (Iberian Chain, Central Spain)

    Science.gov (United States)

    Valcarcel, M.

    2013-05-01

    Manoel Valcárcel1, 5, Ruth Soto2, Elisabet Beamud3, Belén Oliva-Urcia4 and Josep Anton Muñoz5 1 IGME, Departamento de Investigación y Prospección Geocientífica. C/ La Calera, 1, 28760 Tres Cantos; m.valcarcel@igme.es 2 IGME, Unidad de Zaragoza, C/ Manuel Lasala 44, 9 B, 50006 Zaragoza, Spain 3 Lab. Paleomagnetisme (CCiT UB-CSIC). ICT "Jaume Almera", Solé i Sabarís, s/n, 08028 Barcelona, Spain. 4 IPE-CSIC, Avda. Montañana 1005, 50059 Zaragoza, Spain 5 Grup Geodinàmica i Anàlisi de Conques, Universitat de Barcelona, Zona Universitària Pedralbes, 08028 Barcelona, Spain The Altomira and Loranca structures consist of a fold-and-thrust system detached on Triassic evaporites. They are oriented N-S to NNE-SSW and NNW-SSE at its northern and southern end, respectively, forming a subtle arc, oblique with respect to the general NW-SE trend of the Iberian Chain. The aim of this work is to characterize with paleomagnetic data the kinematic evolution of the the Altomira Range, located at the southwestern deformation front of the Iberian Chain, and of the structures within its associated piggy-back basin, the Loranca basin. This approach will also give clues regarding the primary and/or secondary origin of these structures to better characterize them in further studies (3D reconstruction and restoration, fault pattern). A total of 180 samples were obtained from 19 sites in Eocene, Oligocene and Miocene rocks (including clays, fine sandstones and limestones). They were analyzed by means of stepwise thermal demagnetization and subsequent measurement of the natural remanent magnetization (NRM). Although fold tests are not statistically significant, a primary origin of the magnetization is deduced by samples showing either normal or reverse polarity after bedding correction of the calculated characteristic components. Declinations of the site mean directions appear scattered after bedding correction suggesting differential vertical-axis rotations. Sites located at the

  20. Bulk and surface electronic structure of GaN measured using angle resolved photoemission, soft x-ray emission and soft x-ray absorption

    Energy Technology Data Exchange (ETDEWEB)

    Smith, K.E.; Dhesi, S.S.; Duda, L.C.; Stagarescu, C.B.; Singh, R.; Moustakas, T.D. [Boston Univ., MA (United States); Guo, J.H.; Nordgren, J. [Uppsala Univ. (Sweden). Dept. of Physics

    1997-12-31

    The electronic structure of thin film wurtzite GaN has been studied using a combination of angle resolved photoemission, soft x-ray absorption and soft x-ray emission spectroscopies. The authors have measured the bulk valence and conduction band partial density of states by recording Ga L and N K- x-ray emission and absorption spectra. They compare the x-ray spectra to a recent ab initio calculation and find good overall agreement. The x-ray emission spectra reveal that the top of the valence band is dominated by N 2p states, while the x-ray absorption spectra show the bottom of the conduction band as a mixture of Ga 4s and N 2p states, again in good agreement with theory. However, due to strong dipole selection rules the authors can also identify weak hybridization between Ga 4s- and N 2p-states in the valence band. Furthermore, a component to the N K-emission appears at approximately 19.5 eV below the valence band maximum and can be identified as due to hybridization between N 2p and Ga 3d states. They report preliminary results of a study of the full dispersion of the bulk valence band states along high symmetry directions of the bulk Brillouin zone as measured using angle resolved photoemission. Finally, they tentatively identify a non-dispersive state at the top of the valence band in parts of the Brillouin zone as a surface state.

  1. Distinct effects of Cr bulk doping and surface deposition on the chemical environment and electronic structure of the topological insulator Bi{sub 2}Se{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Yilmaz, Turgut, E-mail: yilmaz@phys.uconn.edu [Department of Physics, University of Connecticut, Storrs, CT 06269 (United States); Hines, William [Department of Physics, University of Connecticut, Storrs, CT 06269 (United States); Sun, Fu-Chang [Department of Materials Science and Engineering, University of Connecticut, Storrs, CT 06269 (United States); Pletikosić, Ivo [Department of Physics, Princeton University, Princeton, NJ 08544 (United States); Budnick, Joseph [Department of Physics, University of Connecticut, Storrs, CT 06269 (United States); Valla, Tonica [Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Sinkovic, Boris [Department of Physics, University of Connecticut, Storrs, CT 06269 (United States)

    2017-06-15

    Highlights: • Cr doping into the bulk of Bi{sub 2}Se{sub 3} opens an energy gap at the Dirac point which is observable in the non-magnetic state. • Cr surface deposition does not lead to open an energy gap at the Dirac point of Bi{sub 2}Se{sub 3}. • Formation of two distinct Bi and Cr core level peaks was observed upon the deposition of Cr on the surface of Bi{sub 2}Se{sub 3}. - Abstract: In this report, it is shown that Cr doped into the bulk and Cr deposited on the surface of Bi{sub 2}Se{sub 3} films produced by molecular beam epitaxy (MBE) have strikingly different effects on both the electronic structure and chemical environment. Angle resolved photoemission spectroscopy (ARPES) shows that Cr doped into the bulk opens a surface state energy gap which can be seen at room temperature; much higher than the measured ferromagnetic transition temperature of ≈10 K. On the other hand, similar ARPES measurements show that the surface states remain gapless down to 15 K for films with Cr surface deposition. In addition, core-level photoemission spectroscopy of the Bi 5d, Se 3d, and Cr 3p core levels show distinct differences in the chemical environment for the two methods of Cr introduction. Surface deposition of Cr results in the formation of shoulders on the lower binding energy side for the Bi 5d peaks and two distinct Cr 3p peaks indicative of two Cr sites. These striking differences suggests an interesting possibility that better control of doping at only near surface region may offer a path to quantum anomalous Hall states at higher temperatures than reported in the literature.

  2. A biomechanical analysis of the vertebral and rib deformities in structural scoliosis

    NARCIS (Netherlands)

    Veldhuizen, AG; Klein, JP; Webb, PJ; Nijenbanning, G; Cool, JC; von Horn, [No Value

    Although the structural changes occurring in the scoliotic spine have been reported as early as the 19th century, the descriptions and biomechanical explanations have not always been complete and consistent. In this study, three-dimensionally rendered CT images of two human skeletons with a

  3. Deformation and structure evolution of glassy poly(lactic acid) below the glass transition temperature

    DEFF Research Database (Denmark)

    Zhou, Chengbo; Li, Hongfei; Zhang, Yao

    2015-01-01

    Poly(lactic acid) (PLA) is a bio-based and compostable thermoplastic polyester that has rapidly evolved into a competitive commodity material over the last decade. One key bottleneck in expanding the field of application of PLA is the control of its structure and properties. Therefore, in situ...

  4. A Micromachined Capacitive Pressure Sensor Using a Cavity-Less Structure with Bulk-Metal/Elastomer Layers and Its Wireless Telemetry Application

    Directory of Open Access Journals (Sweden)

    Yogesh B. Gianchandani

    2008-04-01

    Full Text Available This paper reports a micromachined capacitive pressure sensor intended for applications that require mechanical robustness. The device is constructed with two micromachined metal plates and an intermediate polymer layer that is soft enough to deform in a target pressure range. The plates are formed of micromachined stainless steel fabricated by batch-compatible micro-electro-discharge machining. A polyurethane roomtemperature- vulcanizing liquid rubber of 38-μm thickness is used as the deformable material. This structure eliminates both the vacuum cavity and the associated lead transfer challenges common to micromachined capacitive pressure sensors. For frequency-based interrogation of the capacitance, passive inductor-capacitor tanks are fabricated by combining the capacitive sensor with an inductive coil. The coil has 40 turns of a 127-μmdiameter copper wire. Wireless sensing is demonstrated in liquid by monitoring the variation in the resonant frequency of the tank via an external coil that is magnetically coupled with the tank. The sensitivity at room temperature is measured to be 23-33 ppm/KPa over a dynamic range of 340 KPa, which is shown to match a theoretical estimation. Temperature dependence of the tank is experimentally evaluated.

  5. Flow Through Deformable Orifice Diaphragms Used as Heart Valve Analogues

    Science.gov (United States)

    Amatya, Devesh; Longmire, Ellen

    2006-11-01

    Both hemodynamic and structural performance are important considerations in designing replacement heart valves. In this study, compression-molded silicone diaphragms of varying orifice and modulus are used as simplified heart valve analogues. Structural quantities such as diaphragm orifice area and deformation are quantified simultaneously with hemodynamic quantities (flow characteristics). Diaphragms are positioned downstream of a steady fully-developed pipe flow, and velocity fields are quantified both upstream and downstream of each diaphragm using particle image velocimetry (PIV). Diaphragm deformation is obtained from each image, while pressure drop across the diaphragm and volumetric flow rate are measured independently. The combined flow and structural data can be used to validate fluid-structure interaction codes suitable for biomedical applications. The bulk flow results will be compared against the existing hydraulic performance formula for rigid orifice diaphragms, and details of instantaneous flow fields will be presented.

  6. Documenting feedbacks between surface processes and structural deformation in East Timor using stream profile and drainage network analysis

    Science.gov (United States)

    Tate, G. W.; Willett, S.; McQuarrie, N.; Goren, L.; Fox, M.

    2013-12-01

    While river profile analyses have long been used to evaluate the development of landforms, recent advances in analyzing drainage networks have significantly improved the ability to positively link stream profiles with surface uplift. In one such method, Perron and Royden (2012) define the value chi, an integral quantity based on the steady-state stream power equation which aids in determining the conformity of rivers and drainage basins to steady-state behavior. East Timor is an ideal location to test new methods using chi, as it is an active and unglaciated orogen with independent constraints of the deformational history through thermochronology and structural geology. We utilize the calculation of chi in our analyses of the drainage network to provide new constraints on the most recent uplift history of the island of Timor. Discontinuities in chi across drainage divides imply different steady state baselevel for hillslopes and therefore active migration of the divide. We confirm this by noting visible landslides in satellite images and asymmetries in hillslope steepness. Analyses of chi and elevation reveal in some locations that tributaries within a single basin have experienced distinctly different histories, documenting instances where previous river capture has occurred. In other locations the relationships between chi and elevation along single rivers denote spatial changes in surface uplift rate. Many of these observations from the drainage network correspond well to patterns of recent exhumation identified from thermochronologic analyses as well as structural constraints from field mapping and balanced cross-sections. Much of the fastest exhumation on the island (as indicated by zircon (U-Th)/He ages of 1.5-3.8 Ma and modeled exhumation rates of 1-3 mm/yr) is in the hinterland slate belt, which also contains the most stream profile remnants of paleo-capture events. Many locations of active river capture correspond well to independently constrained

  7. Structural, chemical and deformation changes in friction welded joint of dissimilar steels

    Directory of Open Access Journals (Sweden)

    N. Ratković

    2014-10-01

    Full Text Available Fundamental principles of friction welding of dissimilar steels (high speed and tempering steel from the aspect of metallurgical and chemical processes occurring in the joint zone are presented in this paper. Considering that phenomena accompanying the friction welding are interdependent, it was necessary to experimentally determine the process variable parameters, to establish the optimal welding regime. The experiments were set and realized so that all the variables were analyzed as a function of the friction time. The metallographic investigations included analysis of the joint zone microstructure through structural phases and hardness changes, due to influence of the heat treatment - annealing. The experimental work included analysis of the geometry changes, the joint zone structure and the basic mechanical characteristics of the joint realized by the friction welding.

  8. Relaxation of the residual defect structure in deformed polycrystals under ultrasonic action

    Science.gov (United States)

    Murzaev, R. T.; Bachurin, D. V.; Nazarov, A. A.

    2017-07-01

    Using numerical computer simulation, the behavior of disordered dislocation systems under the action of monochromatic standing sound wave has been investigated in the grain of the model two-dimensional polycrystal containing nonequilibrium grain boundaries. It has been found that the presence of grain boundaries markedly affects the behavior of dislocations. The relaxation process and changes in the level of internal stresses caused by the rearrangement of the dislocation structure due to the ultrasonic action have been studied.

  9. Ti{sub 3}GaC{sub 2} and Ti{sub 3}InC{sub 2}: First bulk synthesis, DFT stability calculations and structural systematics

    Energy Technology Data Exchange (ETDEWEB)

    Cuskelly, Dylan T., E-mail: Dylan.cuskelly@uon.edu.au [School of Engineering, The University of Newcastle, Callaghan, NSW 2308 (Australia); Richards, Erin R.; Kisi, Erich H. [School of Engineering, The University of Newcastle, Callaghan, NSW 2308 (Australia); Keast, Vicki J. [School of Mathematical and Physical Sciences, The University of Newcastle, Callaghan, NSW 2308 (Australia)

    2015-10-15

    A simple methodology for identifying possible higher order M{sub n+1}AX{sub n} phases (n≥2) from the chemical characteristics of known phases was developed. The method was used to identify two potential M{sub 3}AC{sub 2} phases Ti{sub 3}GaC{sub 2} and Ti{sub 3}InC{sub 2}. After verifying that the n=1 MAX phases in these systems could be synthesised in bulk using a simple pressureless reactive sintering process, the new phases were synthesised using the same method. DFT calculations were used to test the thermodynamic stability of the new phases against the known competing phases within the same ternary systems. Both were found to be stable although Ti{sub 3}InC{sub 2} only marginally so. Crystal structure refinements and comparison to other MAX phases revealed a linear increase in the c-axis length as a function of the atomic radius of the A element. - Highlights: • Chemical systematics were used to highlight a search window for new MAX phases. • Two new higher order MAX phases, Ti{sub 3}InC{sub 2} and Ti{sub 3}GaC{sub 2}, were synthesised. • Pressureless reactive sintering was effective in producing bulk material. • DFT calculations indicate that the new phases are stable.

  10. Optically induced lattice deformations, electronic structure changes, and enhanced superconductivity in YBa2Cu3O6.48.

    Science.gov (United States)

    Mankowsky, R; Fechner, M; Först, M; von Hoegen, A; Porras, J; Loew, T; Dakovski, G L; Seaberg, M; Möller, S; Coslovich, G; Keimer, B; Dhesi, S S; Cavalleri, A

    2017-07-01

    Resonant optical excitation of apical oxygen vibrational modes in the normal state of underdoped YBa2Cu3O6+x induces a transient state with optical properties similar to those of the equilibrium superconducting state. Amongst these, a divergent imaginary conductivity and a plasma edge are transiently observed in the photo-stimulated state. Femtosecond hard x-ray diffraction experiments have been used in the past to identify the transient crystal structure in this non-equilibrium state. Here, we start from these crystallographic features and theoretically predict the corresponding electronic rearrangements that accompany these structural deformations. Using density functional theory, we predict enhanced hole-doping of the CuO2 planes. The empty chain Cu dy(2)-z(2) orbital is calculated to strongly reduce in energy, which would increase c-axis transport and potentially enhance the interlayer Josephson coupling as observed in the THz-frequency response. From these results, we calculate changes in the soft x-ray absorption spectra at the Cu L-edge. Femtosecond x-ray pulses from a free electron laser are used to probe changes in absorption at two photon energies along this spectrum and provide data consistent with these predictions.

  11. Optically induced lattice deformations, electronic structure changes, and enhanced superconductivity in YBa2Cu3O6.48

    Directory of Open Access Journals (Sweden)

    R. Mankowsky

    2017-07-01

    Full Text Available Resonant optical excitation of apical oxygen vibrational modes in the normal state of underdoped YBa2Cu3O6+x induces a transient state with optical properties similar to those of the equilibrium superconducting state. Amongst these, a divergent imaginary conductivity and a plasma edge are transiently observed in the photo-stimulated state. Femtosecond hard x-ray diffraction experiments have been used in the past to identify the transient crystal structure in this non-equilibrium state. Here, we start from these crystallographic features and theoretically predict the corresponding electronic rearrangements that accompany these structural deformations. Using density functional theory, we predict enhanced hole-doping of the CuO2 planes. The empty chain Cu dy2-z2 orbital is calculated to strongly reduce in energy, which would increase c-axis transport and potentially enhance the interlayer Josephson coupling as observed in the THz-frequency response. From these results, we calculate changes in the soft x-ray absorption spectra at the Cu L-edge. Femtosecond x-ray pulses from a free electron laser are used to probe changes in absorption at two photon energies along this spectrum and provide data consistent with these predictions.

  12. Large-Deformation Curling Actuators Based on Carbon Nanotube Composite: Advanced-Structure Design and Biomimetic Application.

    Science.gov (United States)

    Chen, Luzhuo; Weng, Mingcen; Zhou, Zhiwei; Zhou, Yi; Zhang, Lingling; Li, Jiaxin; Huang, Zhigao; Zhang, Wei; Liu, Changhong; Fan, Shoushan

    2015-12-22

    In recent years, electroactive polymers have been developed as actuator materials. As an important branch of electroactive polymers, electrothermal actuators (ETAs) demonstrate potential applications in the fields of artificial muscles, biomimetic devices, robotics, and so on. Large-shape deformation, low-voltage-driven actuation, and ultrafast fabrication are critical to the development of ETA. However, a simultaneous optimization of all of these advantages has not been realized yet. Practical biomimetic applications are also rare. In this work, we introduce an ultrafast approach to fabricate a curling actuator based on a newly designed carbon nanotube and polymer composite, which completely realizes all of the above required advantages. The actuator shows an ultralarge curling actuation with a curvature greater than 1.0 cm(-1) and bending angle larger than 360°, even curling into a tubular structure. The driving voltage is down to a low voltage of 5 V. The remarkable actuation is attributed not only to the mismatch in the coefficients of thermal expansion but also to the mechanical property changes of materials during temperature change. We also construct an S-shape actuator to show the possibility of building advanced-structure actuators. A weightlifting walking robot is further designed that exhibits a fast-moving motion while lifting a sample heavier than itself, demonstrating promising biomimetic applications.

  13. Understanding the structure and deformation of titanium-containing silicate glasses from their elastic responses to external stimuli

    Science.gov (United States)

    Scannell, Garth

    The responses of structure and properties to composition and temperature have been investigated for glasses in TiO2-SiO2 and Na2O-TiO2-SiO2 systems. Additionally, the response of Na2O-TiO2-SiO2 glasses to plastic deformation has been studied. (x)TiO2-(1-x)SiO2 glasses were prepared through the sol-gel process with compositions 0 ≤ x ≤ 10 mol% and compared to commercial glasses prepared through flame hydrolysis deposition with x = 0, 5.4, and 8.3 mol%. (x) Na2O - (y) TiO 2 - (1-x-y) SiO2 glasses were prepared with x = 10, 15, 20, and 25 mol% and y = 4, 7, and 10 mol% through a melt-quench process. Density and index of refraction of glasses was measured through the Archimedes's method and using a prism coupler, respectively. The glass transition temperature of Na2O-TiO2-SiO2 glasses was measured through differential thermal analysis. The structure and elastic moduli have been studied through Raman spectroscopy and Brillouin light scattering, respectively, at room temperature and in-situ up to 1200 °C for TiO2-SiO2 glasses and up to 800 °C for Na2O-TiO2-SiO2 glasses. Young's modulus was observed to decrease from 72 GPa to 66 GPa with the addition of 8.3 mol% TiO2 in TiO2-SiO2 glasses and to increase from 65 GPa to 73 GPa with the addition of 10 mol% TiO2 in 10 Na2O - (0-10) TiO2-SiO2 glasses. The addition of TiO2 was observed to shift the 460, 490, and 600 cm-1 Raman peaks to lower frequencies in TiO2-SiO2 glasses, suggesting a more open and flexible network, and the 720, 800, and 840 cm -1 Raman peaks to higher frequencies in Na2O-TiO2 -SiO2 glasses, suggesting a lower free volume and stiffer network. The addition of TiO2 has little effect on the temperature response of the elastic moduli in either system, but decreases the thermal expansion and increases the frequency shifts in the 950 and 1100 cm -1 Raman peaks in the TiO2-SiO2 system while the thermal expansion increases with initial additions of TiO2 and then remains constant in the Na2O-TiO2-SiO 2 system

  14. Hierarchical structure and compressive deformation mechanisms of bighorn sheep (Ovis canadensis) horn.

    Science.gov (United States)

    Huang, Wei; Zaheri, Alireza; Jung, Jae-Young; Espinosa, Horacio D; Mckittrick, Joanna

    2017-12-01

    Bighorn sheep (Ovis canadensis) rams hurl themselves at each other at speeds of ∼9 m/s (20 mph) to fight for dominance and mating rights. This necessitates impact resistance and energy absorption mechanisms, which stem from material-structure components in horns. In this study, the material hierarchical structure as well as correlations between the structure and mechanical properties are investigated. The major microstructural elements of horns are found as tubules and cell lamellae, which are oriented with (∼30⁰) angle with respect to each other. The cell lamellae contain keratin cells, in the shape of pancakes, possessing an average thickness of ∼2 µm and diameter of ∼20-30 µm. The morphology of keratin cells reveals the presence of keratin fibers and intermediate filaments with diameter of ∼200 nm and ∼12 nm, respectively, parallel to the cell surface. Quasi-static and high strain rate impact experiments, in different loading directions and hydration states, revealed a strong strain rate dependency for both dried and hydrated conditions. A strong anisotropy behavior was observed under impact for the dried state. The results show that the radial direction is the most preferable impact orientation because of its superior energy absorption. Detailed failure mechanisms under the aforementioned conditions are examined by bar impact recovery experiments. Shear banding, buckling of cell lamellae, and delamination in longitudinal and transverse direction were identified as the cause for strain softening under high strain rate impact. While collapse of tubules occurs in both quasi-static and impact tests, in radial and transverse directions, the former leads to more energy absorption and impact resistance. Bighorn sheep (Ovis canadensis) horns show remarkable impact resistance and energy absorption when undergoing high speed impact during the intraspecific fights. The present work illustrates the hierarchical structure of bighorn sheep horn at

  15. Reaction cross-section calculations using new experimental and theoretical level structure data for deformed nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Hoff, R.W.; Gardner, D.G.; Gardner, M.A.

    1985-05-01

    A technique for modeling level structures of odd-odd nuclei has been used to construct sets of discrete states with energies in the range 0 to 1.5 MeV for several nuclei in the rare-earth and actinide regions. The accuracy of the modeling technique was determined by comparison with experimental data. Examination was made of what effect the use of these new, more complete sets of discrete states has on the calculation of level densities, total reaction cross sections, and isomer ratios. 9 refs.

  16. Effect of heat treatment on the crystal structure of deformed samples of chromium-manganese steel

    Science.gov (United States)

    Chezganov, D. S.; Chikova, O. A.; Borovykh, M. A.

    2017-09-01

    Results of studying microstructures and the crystal structure of samples of 35KhGF steel (0.31-0.38 wt % C, 0.17-0.37 wt % Si, 0.95-1.25 wt % Mn, 1.0-1.3 wt % Cr, 0.06-0.12 wt % V, and the remainder was Fe) have been presented. The samples have been selected from hot-rolled pipes subjected to different heat treatments. A study has been carried out in order to explain the choice of the heat-treatment regime based on determining the structure-properties relationship that provides an increase in the corrosion resistance of pipes to the effect of hydrocarbons. Methods of the energy-dispersive X-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD) have been used. In the microstructure of samples, oxide inclusions and discontinuities with sizes of 1-50 μm that presumably consist of the scale were detected. The ferrite grain size and the orientations of crystals were determined; the data on the local mechanical stresses in the Taylor orientation- factor maps were obtained. The grain refinement; the increase in the fraction of the low-angle boundaries; and the decrease in the local mechanical stresses and, therefore, the highest corrosion resistance to the effect of hydrocarbons is achieved by normalizing at 910°C.

  17. Structural Model for Tubulin Recognition and Deformation by Kinesin-13 Microtubule Depolymerases

    Directory of Open Access Journals (Sweden)

    Ana B. Asenjo

    2013-03-01

    Full Text Available To elucidate the structural basis of the mechanism of microtubule depolymerization by kinesin-13s, we analyzed complexes of tubulin and the Drosophila melanogaster kinesin-13 KLP10A by electron microscopy (EM and fluorescence polarization microscopy. We report a nanometer-resolution (1.1 nm cryo-EM three-dimensional structure of the KLP10A head domain (KLP10AHD bound to curved tubulin. We found that binding of KLP10AHD induces a distinct tubulin configuration with displacement (shear between tubulin subunits in addition to curvature. In this configuration, the kinesin-binding site differs from that in straight tubulin, providing an explanation for the distinct interaction modes of kinesin-13s with the microtubule lattice or its ends. The KLP10AHD-tubulin interface comprises three areas of interaction, suggesting a crossbow-type tubulin-bending mechanism. These areas include the kinesin-13 family conserved KVD residues, and as predicted from the crossbow model, mutating these residues changes the orientation and mobility of KLP10AHDs interacting with the microtubule.

  18. Tuning the electronic structure of bulk FeSe with chemical pressure using quantum oscillations and angle resolved photoemission spectroscopy (ARPES)

    Science.gov (United States)

    Coldea, Amalia

    FeSe is a unique and intriguing superconductor which can be tuned into a high temperature superconducting state using applied pressure, chemical intercalation and surface doping. In the absence of magnetism, the structural transition in FeSe is believed to be electronically driven, with the orbital degrees of freedom playing an important part. This scenario supports the stabilization of a nematic state in FeSe, which manifests as a Fermi surface deformation in the presence of strong interactions, as detected by ARPES. Another manifestation of the nematicity is the enhanced nematic susceptibility determined from elastoresistance measurements under applied strain. Isovalent Sulphur substitution onto the Selenium site constitutes a chemical pressure, which subtly modifies the electronic structure of FeSe, suppressing the structural transition without inducing high temperature superconductivity. I will present the evolution of the electronic structure with chemical pressure in FeSe, as determined from quantum oscillations and ARPES studies and I will discuss the suppression of the nematic electronic state and the role of electronic correlations. Experiments were performed at high magnetic field facilities in Tallahassee, Nijmegen and Toulouse and Diamond Light Source, UK. This work is mainly supported by EPSRC, UK (EP/I004475/1, EP/I017836/1) and I acknowledge my collaborators from Refs. .

  19. Structure and properties of YBa2Cu3O7-δ superconductor doped with bulk cadmium oxide

    Directory of Open Access Journals (Sweden)

    A Echresh

    2010-09-01

    Full Text Available In this paper, the Y1-xCdxBa2Cu3O7-δ superconductor with x=0, 0.05, 0.1, 0.15, 0.2, 0.3, 0.4, 0.5 are prepared using the solid state method and the structure, electrical resistance, critical current density and critical temperature of it, have been studied. The results show that these doping do not affect so much on the structure and lattice parameters. The electrical resistance of samples increased with doping. A little amount of doping cadmium improve critical current density such that the sample x=0.1 has a maximum critical current density among the samples. The critical temperature with doping cadmium up to x=0.2 has little fluctuation and its variation can be ignored, but by increasing up to x=0.5 the critical temperature decreases gradually.

  20. Structural relaxations in the bulk amorphous alloy Fe{sub 61}Co{sub 10}Ti{sub 3}Y{sub 6}B{sub 20}

    Energy Technology Data Exchange (ETDEWEB)

    Błoch, K., E-mail: 23kasia1@wp.pl; Nabiałek, M.; Gondro, J.

    2017-05-01

    The paper presents studies of annealing effect on the disaccommodation phenomenon in bulk amorphous alloy Fe{sub 61}Co{sub 10}Ti{sub 3}Y{sub 6}B{sub 20}. The investigated sample was prepared by suction-casting method in the form of rod. The annealing process has been performed at temperature well below the crystallisation temperature. The amorphous structure has been confirmed using X-ray diffractometer. The susceptibility and its disaccommodation were determined using completely automated set up. The disaccommodation curve was decomposed into three elementary processes, each of them was described by Gaussian distribution of relaxation times. The obtained results indicate that the disaccommodation phenomenon in studied alloy is related with directional ordering of atom pairs near the free volumes; this is in agreement with H. Kronmüller's theorem.

  1. Glacio-tectonic thrust and deformation structures in the Vejle Fjord, Denmark revealed by high-resolution subbottom-profile data

    DEFF Research Database (Denmark)

    Andresen, Katrine Juul; Boldreel, Lars Ole; Wahlgreen, Katrine Bak

    Surface geomorphological features and partial cliff exposures up till now represent the predominant source of information of glaciation related deformation in Denmark. In this study we apply high-resolution marine reflection seismic data from the Vejle Fjord area, supported by gravity and Rumohr...... coring, to document intense glacio-tectonic deformation in the shallow subsurface of Denmark. The subbottom profiler seismic data have a peak frequency around 13 kHz and a vertical resolution in the order of 10-20 cm. The data reveal several variations of glacio-tectonic deformation structures, primarily...... observed near the edges of the fjord where coarse-grained and sandy deposits are present. These sediments allows for an exceptionally good and high-resolution imaging of the marine shallow subsurface. Within the central regions of the fjord, widespread shallow gas accumulations probably generated from...

  2. Influence of the irradiation temperature on the surface structure and physical/chemical properties of Ar ion-irradiated bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Menéndez, E., E-mail: Enric.MenendezDalmau@fys.kuleuven.be [KU Leuven, Instituut voor Kern-en Stralingsfysica, Celestijnenlaan 200 D, 3001 Leuven (Belgium); Hynowska, A.; Fornell, J.; Suriñach, S. [Departament de Física, Facultat de Ciències, Universitat Autònoma de Barcelona, E-08193 Bellaterra (Spain); Montserrat, J. [Institut de Microelectrònica de Barcelona (IMB-CNM), CSIC, Campus Universitat Autònoma Barcelona, E-08193 Bellaterra (Spain); Temst, K.; Vantomme, A. [KU Leuven, Instituut voor Kern-en Stralingsfysica, Celestijnenlaan 200 D, 3001 Leuven (Belgium); Baró, M.D. [Departament de Física, Facultat de Ciències, Universitat Autònoma de Barcelona, E-08193 Bellaterra (Spain); García-Lecina, E. [Surfaces Division, IK4-CIDETEC, Parque Tecnológico de San Sebastián, E-20009 Donostia (Spain); Pellicer, E., E-mail: Eva.Pellicer@uab.cat [Departament de Física, Facultat de Ciències, Universitat Autònoma de Barcelona, E-08193 Bellaterra (Spain); Sort, J., E-mail: Jordi.Sort@uab.cat [Institució Catalana de Recerca i Estudis Avançats (ICREA) and Departament de Física, Universitat Autònoma de Barcelona, E-08193 Bellaterra (Spain)

    2014-10-15

    Highlights: • Ion irradiation is performed on bulk metallic glasses at 300 K and close to T{sub g}. • Nanocrystallization is observed after high-temperature irradiation. • The mechanical properties are enhanced after the irradiation procedures. • Corrosion resistance is improved after irradiation close to T{sub g}. - Abstract: Surface treatments using multiple Ar ion irradiation processes with a maximum energy and fluence of 200 keV and 1 × 10{sup 16} ions/cm{sup 2}, respectively, have been performed on two different metallic glasses: Zr{sub 55}Cu{sub 28}Al{sub 10}Ni{sub 7} and Ti{sub 40}Zr{sub 10}Cu{sub 38}Pd{sub 12}. Analogous irradiation procedures have been carried out at room temperature (RT) and at T = 620 K (≈0.9 T{sub g}, where T{sub g} denotes the glass transition). The structure, mechanical behavior, wettability and corrosion resistance of the irradiated alloys have been compared with the properties of the as-cast and annealed (T = 620 K) non-irradiated specimens. While ion irradiation at RT does not significantly alter the amorphous structure of the alloys, ion irradiation close to T{sub g} promotes decomposition/nanocrystallization. Consequently, the hardness (H) and reduced Young’s modulus (E{sub r}) decrease after irradiation at RT but they both increase after irradiation at 620 K. While annealing close to T{sub g} increases the hydrophobicity of the samples, irradiation induces virtually no changes in the contact angle when comparing with the as-cast state. Concerning the corrosion resistance, although not much effect is found after irradiation at RT, an improvement is observed after irradiation at 620 K, particularly for the Ti-based alloy. These results are of practical interest in order to engineer appropriate surface treatments based on ion irradiation, aimed at specific functional applications of bulk metallic glasses.

  3. Catalytic Hydrogenation of Levulinic Acid in Water into g-Valerolactone over Bulk Structure of Inexpensive Intermetallic Ni-Sn Alloy Catalysts

    Directory of Open Access Journals (Sweden)

    Rodiansono Rodiansono

    2015-07-01

    Full Text Available A bulk structure of inexpensive intermetallic nickel-tin (Ni-Sn alloys catalysts demonstrated highly selective in the hydrogenation of levulinic acid in water into g-valerolactone. The intermetallic Ni-Sn catalysts were synthesized via a very simple thermochemical method from non-organometallic precursor at low temperature followed by hydrogen treatment at 673 K for 90 min. The molar ratio of nickel salt and tin salt was varied to obtain the corresponding Ni/Sn ratio of 4.0, 3.0, 2.0, 1.5, and 0.75. The formation of Ni-Sn alloy species was mainly depended on the composition and temperature of H2 treatment. Intermetallics Ni-Sn that contain Ni3Sn, Ni3Sn2, and Ni3Sn4 alloy phases are known to be effective heterogeneous catalysts for levulinic acid hydrogenation giving very excellence g-valerolactone yield of >99% at 433 K, initial H2 pressure of 4.0 MPa within 6 h. The effective hydrogenation was obtained in H2O without the formation of by-product. Intermetallic Ni-Sn(1.5 that contains Ni3Sn2 alloy species demonstrated very stable and reusable catalyst without any significant loss of its selectivity. © 2015 BCREC UNDIP. All rights reserved. Received: 26th February 2015; Revised: 16th April 2015; Accepted: 22nd April 2015  How to Cite: Rodiansono, R., Astuti, M.D., Ghofur, A., Sembiring, K.C. (2015. Catalytic Hydrogenation of Levulinic Acid in Water into g-Valerolactone over Bulk Structure of Inexpensive Intermetallic Ni-Sn Alloy Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (2: 192-200. (doi:10.9767/bcrec.10.2.8284.192-200Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.2.8284.192-200  

  4. Effects of alkyl chain length and substituent pattern of fullerene bis-adducts on film structures and photovoltaic properties of bulk heterojunction solar cells.

    Science.gov (United States)

    Tao, Ran; Umeyama, Tomokazu; Kurotobi, Kei; Imahori, Hiroshi

    2014-10-08

    A series of alkoxycarbonyl-substituted dihydronaphthyl-based [60]fullerene bis-adduct derivatives (denoted as C2BA, C4BA, and C6BA with the alkyl chain of ethyl, n-butyl, and n-hexyl, respectively) have been synthesized to investigate the effects of alkyl chain length and substituent pattern of fullerene bis-adducts on the film structures and photovoltaic properties of bulk heterojunction polymer solar cells. The shorter alkyl chain length caused lower solubility of the fullerene bis-adducts (C6BA > C4BA > C2BA), thereby resulting in the increased separation difficulty of respective bis-adduct isomers. The device performance based on poly(3-hexylthiophene) (P3HT) and the fullerene bis-adduct regioisomer mixtures was enhanced by shortening the alkyl chain length. When using the regioisomerically separated fullerene bis-adducts, the devices based on trans-2 and a mixture of trans-4 and e of C4BA exhibited the highest power conversion efficiencies of ca. 2.4%, which are considerably higher than those of the C6BA counterparts (ca. 1.4%) and the C4BA regioisomer mixture (1.10%). The film morphologies as well as electron mobilities of the P3HT:bis-adduct blend films were found to affect the photovoltaic properties considerably. These results reveal that the alkyl chain length and substituent pattern of fullerene bis-adducts significantly influence the photovoltaic properties as well as the film structures of bulk heterojunction solar cells.

  5. Crystallite size effect on the monoclinic deformation of the bcc crystal structure of chromium

    Science.gov (United States)

    Przeniosło, R.; Fabrykiewicz, P.; Sosnowska, I.; Wardecki, D.; Sławiński, W. A.; Playford, H. Y.; Hempelmann, R.; Bukowski, M.

    2018-02-01

    The modulated spin density wave magnetic orderings observed in chromium suggests that the crystal structure of chromium cannot be described by the cubic space group Im 3 bar m. Our experimental studies of polycrystalline and nanocrystalline chromium by synchrotron radiation (SR) and neutron powder diffraction show a hkl-dependent Bragg peak broadening which can be interpreted by the low-symmetry monoclinic space group P21 / n instead of the high symmetry cubic space group Im 3 bar m. The monoclinic angle is βm = 90.05(1)° and 90.29(1)° for polycrystalline Cr and nanocrystalline Cr, respectively. The relative monoclinic distortion observed in chromium is 5 times larger than those reported for several oxides: BiFeO3, α-Fe2O3, Cr2O3 and calcite. The symmetry of the magnetic transverse spin density wave (TSDW) and the longitudinal spin density wave (LSDW) observed in Cr are described by using the superspace groups P21 / n(0 β 0) 00 and P 21‧ /n‧(0 β 0) 00, respectively. These superspace groups describe both the magnetic modulations and the atomic position modulations reported in the literature. The monoclinic symmetry of chromium is a robust effect which is observed in the paramagnetic as well as in the TSDW and LSDW phases.

  6. Structure and Properties of Nanoparticles Fabricated by Laser Ablation of Bulk Metal Copper Targets in Water and Ethanol

    Science.gov (United States)

    Goncharova, D. A.; Lapin, I. N.; Savelyev, E. S.; Svetlichnyi, V. A.

    2017-11-01

    Colloidal solutions of nanoparticles (NPs) are prepared by nanosecond pulsed laser ablation (upon exposure to Nd:YAG laser radiation at a wavelength of 1064 nm with a pulse duration of 7 ns) of a copper target in water and ethyl alcohol. Their composition, structure, and optical properties are investigated. It is shown that monovalent Cu2O NPs are mainly formed in water, whereas metal Cu NPs are mainly formed in ethanol. The nonlinear transmission of colloids at wavelengths of 532 and 1064 nm is investigated. It is established that they effectively limit the nanosecond laser pulse power at a wavelength of 532 nm.

  7. Plastic deformation

    NARCIS (Netherlands)

    Sitter, de L.U.

    1937-01-01

    § 1. Plastic deformation of solid matter under high confining pressures has been insufficiently studied. Jeffreys 1) devotes a few paragraphs to deformation of solid matter as a preface to his chapter on the isostasy problem. He distinguishes two properties of solid matter with regard to its

  8. Structurally Deformed MoS2 for Electrochemically Stable, Thermally Resistant, and Highly Efficient Hydrogen Evolution Reaction

    KAUST Repository

    Chen, Yen-Chang

    2017-10-12

    The emerging molybdenum disulfide (MoS2) offers intriguing possibilities for realizing a transformative new catalyst for driving the hydrogen evolution reaction (HER). However, the trade-off between catalytic activity and long-term stability represents a formidable challenge and has not been extensively addressed. This study reports that metastable and temperature-sensitive chemically exfoliated MoS2 (ce-MoS2) can be made into electrochemically stable (5000 cycles), and thermally robust (300 °C) while maintaining synthetic scalability and excellent catalytic activity through physical-transformation into 3D structurally deformed nanostructures. The dimensional transition enabled by a high throughput electrohydrodynamic process provides highly accessible, and electrochemically active surface area and facilitates efficient transport across various interfaces. Meanwhile, the hierarchically strained morphology is found to improve electronic coupling between active sites and current collecting substrates without the need for selective engineering the electronically heterogeneous interfaces. Specifically, the synergistic combination of high strain load stemmed from capillarity-induced-self-crumpling and sulfur (S) vacancies intrinsic to chemical exfoliation enables simultaneous modulation of active site density and intrinsic HER activity regardless of continuous operation or elevated temperature. These results provide new insights into how catalytic activity, electrochemical-, and thermal stability can be concurrently enhanced through the physical transformation that is reminiscent of nature, in which properties of biological materials emerge from evolved dimensional transitions.

  9. Deformation and Recrystallization Behavior of the Cast Structure in Large Size, High Strength Steel Ingots: Experimentation and Modeling

    Science.gov (United States)

    Chadha, K.; Shahriari, D.; Tremblay, R.; Bhattacharjee, P. P.; Jahazi, M.

    2017-09-01

    Constitutive modeling of the ingot breakdown process of large size ingots of high strength steel was carried out through comprehensive thermomechanical processing using Gleeble 3800® thermomechanical simulator, finite element modeling (FEM), optical and electron back scatter diffraction (EBSD). For this purpose, hot compression tests in the range of 1473 K to 1323 K (1200 °C to 1050 °C) and strain rates of 0.25 to 2 s-1 were carried out. The stress-strain curves describing the deformation behavior of the dendritic microstructure of the cast ingot were analyzed in terms of the Arrhenius and Hansel-Spittel models which were implemented in Forge NxT 1.0® FEM software. The results indicated that the Arrhenius model was more reliable in predicting microstructure evolution of the as-cast structure during ingot breakdown, particularly the occurrence of dynamic recrystallization (DRX) process which was a vital parameter in estimating the optimum loads for forming of large size components. The accuracy and reliability of both models were compared in terms of correlation coefficient (R) and the average absolute relative error (ARRE).

  10. Modelling of bulk superconductor magnetization

    Science.gov (United States)

    Ainslie, M. D.; Fujishiro, H.

    2015-05-01

    This paper presents a topical review of the current state of the art in modelling the magnetization of bulk superconductors, including both (RE)BCO (where RE = rare earth or Y) and MgB2 materials. Such modelling is a powerful tool to understand the physical mechanisms of their magnetization, to assist in interpretation of experimental results, and to predict the performance of practical bulk superconductor-based devices, which is particularly important as many superconducting applications head towards the commercialization stage of their development in the coming years. In addition to the analytical and numerical techniques currently used by researchers for modelling such materials, the commonly used practical techniques to magnetize bulk superconductors are summarized with a particular focus on pulsed field magnetization (PFM), which is promising as a compact, mobile and relatively inexpensive magnetizing technique. A number of numerical models developed to analyse the issues related to PFM and optimise the technique are described in detail, including understanding the dynamics of the magnetic flux penetration and the influence of material inhomogeneities, thermal properties, pulse duration, magnitude and shape, and the shape of the magnetization coil(s). The effect of externally applied magnetic fields in different configurations on the attenuation of the trapped field is also discussed. A number of novel and hybrid bulk superconductor structures are described, including improved thermal conductivity structures and ferromagnet-superconductor structures, which have been designed to overcome some of the issues related to bulk superconductors and their magnetization and enhance the intrinsic properties of bulk superconductors acting as trapped field magnets. Finally, the use of hollow bulk cylinders/tubes for shielding is analysed.

  11. Seismic structure across the Caledonian Deformation Front along MONA LISA profile 1 in the southeastern North Sea

    Science.gov (United States)

    Abramovitz, Tanni; Thybo, Hans; MONA LISA Working Group

    1998-03-01

    Seismic data from the MONA LISA (Marine and Onshore North Sea Acquisition for Lithospheric Seismic Analysis) project in the southeastern North Sea image the Caledonian Deformation Front (CDF), which is the collisional suture between Baltica to the north and east and Avalonia to the south and west. The NS-trending MONA LISA normal-incidence reflection profile 1 was recorded to 26 s twt. Coincident wide-angle data were acquired on nine ocean bottom hydrophones and several onshore mobile seismographs along and off the profile. The model of compressional seismic velocity shows three different crustal types: (a) a typical three-layered shield-type crust below the Ringkøbing Fyn High to the north: (b) a highly complex transitional crust in the central part; and (c) a two-layered crust of Caledonian origin to the south. Sharp and strong normal-incidence and wide-angle reflections from Moho were recorded south of the Caledonian Deformation Front in contrast to less distinct reflections further north. S-dipping crustal reflections from 4 to 11 s twt over ˜70 km horizontal distance terminate at Moho and coincide with a change in the seismic velocity structure. This indicates northward obduction of Avalonian crust. Non-migrated normal-incidence seismic sections show crossing weak N-dipping and stronger S-dipping reflections to 20 s twt from the uppermost mantle. We propose a tectonic model where the closure of the Tornquist Sea took place along a N-dipping subduction zone which was later overprinted by a late-or post-Caledonian S-dipping shear zone. Sub-Moho velocities are 7.8-7.9 km/s under 34-35-km-thick Baltica crust and 8.1-8.3 km/s under 25-26-km-thick Caledonian crust. The sub-horizontal Moho across the Caledonian collision zone implies late- or post-Caledonian re-equilibration of the seismological Moho. We interpret the low-velocity upper mantle (7.8-8.1 km/s) to the north as former Baltica lower crust in eclogite facies after pressure-induced metamorphism as a

  12. Towards the determination of deformation rates - pinch-and-swell structures as a natural and simulated paleo-strain rate gage

    Science.gov (United States)

    Peters, Max; Poulet, Thomas; Karrech, Ali; Regenauer-Lieb, Klaus; Herwegh, Marco

    2014-05-01

    Layered rocks deformed under viscous deformation conditions frequently show boudinage, a phenomenon that results from differences in effective viscosity between the involved layers. In the case of continuous necking of a mechanically stiffer layer embedded in a weaker matrix, symmetric boudins are interpreted as the result of dominant visco-plastic deformation (Goscombe et al., 2004). However, information on the physical conditions, material properties and deformation processes are yet unknown. Natural samples deformed under low-grade (Tthermodynamic approach of Regenauer-Lieb and Yuen (2004). Depending on the dissipated energy, grain sizes in these domains vary substantially in space and time. While low strain rates (low stresses) in the swells favor grain growth and GSI dominated deformation, high strain rates in the pinches provoke dramatic grain size reduction with an increasing contribution of GSS as a function of decreasing grain size. The development of symmetric necks observed in nature thus seems to coincide with the transition from dislocation to diffusion creep dominated flow with continuous grain size reduction and growth from swell to neck at relatively high extensional strains. REFERENCES Austin, N. and Evans, B. (2007). Paleowattmeters: A scaling relation for dynamically recrystallized grain size. Geology, 35. Goscombe, B.D., Passchier, C.W. and Hand, M. (2004). Boudinage classification: End-member boudin types and modified boudin structures, Journal of Structural Geology, 26. Herwegh, M., Poulet, T., Karrech, A. and Regenauer-Lieb, K. (in press). From transient to steady state deformation and grain size: A thermodynamic approach using elasto-visco-plastic numerical modeling. Journal of Geophysical Research. Karrech, A., Regenauer-Lieb, K. and Poulet, T. (2011a). A Damaged visco-plasticity model for pressure and temperature sensitive geomaterials. Journal of Engineering Science 49. Regenauer-Lieb, K. and Yuen, D. (2004). Positive feedback of

  13. Structural monitoring and modeling of the mechanical deformation of three-dimensional printed poly(ε-caprolactone) scaffolds.

    Science.gov (United States)

    Ribeiro, João F M; Oliveira, Sara M; Alves, José L; Pedro, Adriano J; Reis, Rui L; Fernandes, Emanuel M; Mano, João F

    2017-05-11

    Three-dimensional (3D) printed poly(ε-caprolactone) (PCL) based scaffolds have being proposed for different tissue engineering applications. This study addresses the design and fabrication of 3D PCL constructs with different struts alignments at 90°, 45° and 90° with offset. The morphology and the mechanical behavior under uniaxial compressive load were assessed at different strain percentages. The combination of a new compressionCT device and micro computed tomography (micro-CT) allowed understanding the influence of pore geometry under controlled compressive strain in the mechanical and structural behavior of PCL constructs. Finite element analysis (FEA) was applied using the micro-CT data to modulate the mechanical response and compare with the conventional uniaxial compression tests. Scanning electron microscopic analysis showed a very high level of reproducibility and a low error comparing with the theoretical values, confirming that the alignment and the dimensional features of the printed struts are reliable. The mechanical tests showed that the 90° architecture presented the highest stiffness. With the compressionCT device was observed that the 90° and 90° with offset architectures presented similar values of porosity at same strain and similar pore size, contrary to the 45° architecture. Thus, pore geometric configurations affected significantly the deformability of the all PCL scaffolds under compression. The prediction of the FEA showed a good agreement to the conventional mechanical tests revealing the areas more affected under compression load. The methodology proposed in this study using 3D printed scaffolds with compressionCT device and FEA is a framework that offers great potential in understanding the mechanical and structural behavior of soft systems for different applications, including for the biomedical engineering field.

  14. Differential Radar Interferometry for Structural and Ground Deformation Monitoring: A New Tool for the Conservation and Sustainability of Cultural Heritage Sites

    Directory of Open Access Journals (Sweden)

    Wei Zhou

    2015-02-01

    Full Text Available Affected by natural and human-induced factors, cultural heritage sites and their surroundings face threats of structural instability and land displacement. Accurate and rapid identification of the key areas facing existing or potential deformation risks is essential for the conservation and sustainability of heritage sites, particularly for huge archaeological regions. In recent years, the successful application of differential radar interferometry techniques for the measurement of millimeter-level terrain motions has demonstrated their potential for deformation monitoring and preventive diagnosis of cultural heritage sites. In this paper, we review the principles of advanced differential radar interferometry approaches and their applicability for structural and ground deformation monitoring over heritage sites. Then, the advantages and challenges of these approaches are analyzed, followed by a discussion on the selection of radar interferometry systems for different archaeological applications. Finally, a workflow, integrating space-borne and ground-based differential radar interferometry technologies for deformation anomaly monitoring and preventive diagnosis of cultural heritage sites, is proposed.

  15. A Structural Approach to Establishing a Platform Chemistry for the Tunable, Bulk Electron Beam Cross-Linking of Shape Memory Polymer Systems.

    Science.gov (United States)

    Hearon, Keith; Besset, Celine J; Lonnecker, Alexander T; Ware, Taylor; Voit, Walter E; Wilson, Thomas S; Wooley, Karen L; Maitland, Duncan J

    2013-11-26

    The synthetic design and thermomechanical characterization of shape memory polymers (SMPs) built from a new polyurethane chemistry that enables facile, bulk and tunable cross-linking of low-molecular weight thermoplastics by electron beam irradiation is reported in this study. SMPs exhibit stimuli-induced geometry changes and are being proposed for applications in numerous fields. We have previously reported a polyurethane SMP system that exhibits the complex processing capabilities of thermoplastic polymers and the mechanical robustness and tunability of thermomechanical properties that are often characteristic of thermoset materials. These previously reported polyurethanes suffer practically because the thermoplastic molecular weights needed to achieve target cross-link densities severely limit high-throughput thermoplastic processing and because thermally unstable radiation-sensitizing additives must be used to achieve high enough cross-link densities to enable desired tunable shape memory behavior. In this study, we demonstrate the ability to manipulate cross-link density in low-molecular weight aliphatic thermoplastic polyurethane SMPs (Mw as low as ~1.5 kDa) without radiation-sensitizing additives by incorporating specific structural motifs into the thermoplastic polymer side chains that we hypothesized would significantly enhance susceptibility to e-beam cross-linking. A custom diol monomer was first synthesized and then implemented in the synthesis of neat thermoplastic polyurethane SMPs that were irradiated at doses ranging from 1 to 500 kGy. Dynamic mechanical analysis (DMA) demonstrated rubbery moduli to be tailorable between 0.1 and 55 MPa, and both DMA and sol/gel analysis results provided fundamental insight into our hypothesized mechanism of electron beam cross-linking, which enables controllable bulk cross-linking to be achieved in highly processable, low-molecular weight thermoplastic shape memory polymers without sensitizing additives.

  16. Structure and tectonic evolution of the southwestern Trinidad dome, Escambray complex, Central Cuba: Insights into deformation in an accretionary wedge

    Science.gov (United States)

    Despaigne-Díaz, Ana Ibis; García Casco, Antonio; Cáceres Govea, Dámaso; Wilde, Simon A.; Millán Trujillo, Guillermo

    2017-10-01

    The Trinidad dome, Escambray complex, Cuba, forms part of an accretionary wedge built during intra-oceanic subduction in the Caribbean from the Late Cretaceous to Cenozoic. The structure reflects syn-subduction exhumation during thickening of the wedge, followed by extension. Field mapping, metamorphic and structural analysis constrain the tectonic evolution into five stages. Three ductile deformation events (D1, D2 and D3) are related to metamorphism in a compressional setting and formation of several nappes. D1 subduction fabrics are only preserved as relict S1 foliation and rootless isoclinal folds strongly overprinted by the main S2 foliation. The S2 foliation is parallel to sheared serpentinised lenses that define tectonic contacts, suggesting thrust stacks and underthrusting at mantle depths. Thrusting caused an inverted metamorphic structure with higher-grade on top of lower-grade nappes. Exhumation started during D2 when the units were incorporated into the growing accretionary wedge along NNE-directed thrust faults and was accompanied by substantial decompression and cooling. Folding and thrusting continued during D3 and marks the transition from ductile to brittle-ductile conditions at shallower crustal levels. The D4-5 events are related to extension and contributed to the final exhumation (likely as a core complex). D4 is associated with a regional spaced S4 cleavage, late open folds, and numerous extension veins, whereas D5 is recorded by normal and strike-slip faults affecting all nappes. The P-t path shows rapid exhumation during D2 and slower rates during D3 when the units were progressively incorporated into the accretionary prism. The domal shape formed in response to tectonic denudation assisted by normal faulting and erosion at the surface during the final stages of structural development. These results support tectonic models of SW subduction of the Proto-Caribbean crust under the Caribbean plate during the latest Cretaceous and provide

  17. Intelligent Material Systems and Structures (IMSS). Part 5: Fiber optic registration of deformation in carbon laminates 91/92

    Science.gov (United States)

    Oedman, Svante; Bengtsson, Jan-Peter; Danilsons, Markus; Dickman, Ola; Gruffman, Stig; Lindersson, Kjell; Tanriverdi, Timor

    1993-02-01

    Mechanical deformations induced by stretching optical fibers and epoxy-carbon laminates with embedded optical fibers were studied with fiber optic measurement technology: intensity measurements, reflectometry, and interferometry. The results from the measurements were compared in order to judge which method could be further developed for strain measurement in a laboratory. The conclusion is that the interferometry can be developed into a laboratory method for measuring deformations in carbon laminates.

  18. The origin and significance of load-induced deformation structures in soft-sediment and lava at the base of the Archaean Ventersdorp Supergroup, South Africa

    Science.gov (United States)

    Hall, R. C. B.; Els, B. G.

    2002-07-01

    Many sedimentary deposits throughout the geologic record display structures that indicate the post-depositional disruption of their primary sedimentary features. Characteristically, the deformation, leading to irregular, broken or shifted stratification, takes place soon after deposition. The process of soft-sediment deformation, to which it is more commonly referred, can be attributed to four main mechanisms: reverse density gradation, liquefaction, slumping (slope deposit) and shear stress exerted by flow. Two or more of these mechanisms may act together and are notably described in purely sedimentary environments. As such, soft-sediment deformation can be considered an intra-formational response to the accumulation of a sediment pile, being largely confined to a single (sedimentary) bed, within undeformed (sedimentary) beds. However, deformation structures may also form where two compositionally and genetically contrasting substrates occur in intimate juxtaposition, as in the case of a volcano-sedimentary setting. Recognizable `soft-igneous' structures, analogous to those observed in sedimentary deposits, may form where lava flows have extruded over water-saturated sediments. In this instance, the lava `bed' substitutes for a sedimentary bed by inducing loading of the underlying sediments, resulting in the formation of deformation structures within both substrates, at their common interface. Such a situation commonly arises at the base of the Klipriviersberg Group, a±2000 m volcanic pile comprising the lower formations of the Ventersdorp Supergroup. Deformation structures in what was once soft-sediment and lava, commonly occur where lava flows comprising the basal Formation(s) of the Klipriviersberg Group overlie a pervasive, multi-lateral, multi-storey sand and gravel placer, the Ventersdorp Contact Reef (VCR). The VCR by definition forms the basal, (auriferous) conglomeratic portion of the Venterspost Conglomerate Formation (VCF) and is developed to varying

  19. 19 CFR 149.4 - Bulk and break bulk cargo.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from the...

  20. Fiber Diffraction of the Prion-Forming Domain HET-s(218-289) Shows Dehydration-Induced Deformation of a Complex Amyloid Structure

    Energy Technology Data Exchange (ETDEWEB)

    Wan, William; Stubbs, Gerald [Vanderbilt

    2014-05-01

    Amyloids are filamentous protein aggregates that can be formed by many different proteins and are associated with both disease and biological functions. The pathogenicities or biological functions of amyloids are determined by their particular molecular structures, making accurate structural models a requirement for understanding their biological effects. One potential factor that can affect amyloid structures is hydration. Previous studies of simple stacked β-sheet amyloids have suggested that dehydration does not impact structure, but other studies indicated dehydration-related structural changes of a putative water-filled nanotube. Our results show that dehydration significantly affects the molecular structure of the fungal prion-forming domain HET-s(218–289), which forms a β-solenoid with no internal solvent-accessible regions. The dehydration-related structural deformation of HET-s(218–289) indicates that water can play a significant role in complex amyloid structures, even when no obvious water-accessible cavities are present.

  1. Contracture deformity

    Science.gov (United States)

    Deformity - contracture ... Contracture can be caused by any of the following: Brain and nervous system disorders, such as cerebral ... Follow your health care provider's instructions for treating contracture at home. Treatments may include: Doing exercises and ...

  2. The Long-term deformation of the Longmen Shan (Sichuan, China), a key to understand the present structure of the eastern Tibet

    Science.gov (United States)

    Airaghi, Laura; de Sigoyer, Julia; Guillot, Stéphane; Lanari, Pierre; Warren, Clare J.; Robert, Alexandra

    2017-04-01

    The Longmen Shan thrust belt, at the eastern border of Tibetan plateau, is a tectonically active region as demonstrated by the Mw 7.9 Wenchuan (2008) and Mw 6.6 Lushan (2013) earthquakes. The Moho discontinuity deepens across the Longmen Shan (below the along-strike Wenchuan fault) from ˜40 km beneath the Sichuan basin to more than 60 km beneath the Songpan-Ganze block. Such a thickness is not compatible with the only ˜35 km of shortening estimated at the front of the belt during the Cenozoic-Quaternary compressive reactivation. The geological inheritance may thus play a key role in the present structure of the Longmen Shan. However the long-term history of the belt is still poorly documented. The major Wenchuan fault separates medium-grade metamorphic rocks to the West (internal domain of the Longmen Shan) to the greenschist metamorphic rocks to the East (external domain). In the hanging and footwall of the fault the South China basement also crops out. Metamorphic rocks, exhumed from depth, offer the opportunity to investigate the deep processes occurred in the Longmen Shan. We have characterized and dated the metamorphism in the central part of the belt by combining structural and microstructural observations with high-resolution X-ray mapping and chemical analyses of metamorphic minerals related to the different stages of deformation. In situ 40Ar/39Ar dating on mica and in situ U-Pb/Th dating on allanite (REE-rich epidote) allowed the different phases of metamorphism and deformation to be dated. Our results show that the Longmen Shan underwent a complex Mesozoic tectono-metamorphic history, articulated in a succession of pulses of deformation (burial or uplifting) and periods of quiescence. A first phase of rapid thin-skinned deformation occurred about 200 Ma ago. Internal sedimentary units were strongly deformed and buried down to 11±1 kbar, 550±30˚ C. This phase was followed by a period of slow exhumation between 200 and 170 Ma. A second pulse of

  3. Creating bulk nanocrystalline metal.

    Energy Technology Data Exchange (ETDEWEB)

    Fredenburg, D. Anthony (Georgia Institute of Technology, Atlanta, GA); Saldana, Christopher J. (Purdue University, West Lafayette, IN); Gill, David D.; Hall, Aaron Christopher; Roemer, Timothy John (Ktech Corporation, Albuquerque, NM); Vogler, Tracy John; Yang, Pin

    2008-10-01

    Nanocrystalline and nanostructured materials offer unique microstructure-dependent properties that are superior to coarse-grained materials. These materials have been shown to have very high hardness, strength, and wear resistance. However, most current methods of producing nanostructured materials in weapons-relevant materials create powdered metal that must be consolidated into bulk form to be useful. Conventional consolidation methods are not appropriate due to the need to maintain the nanocrystalline structure. This research investigated new ways of creating nanocrystalline material, new methods of consolidating nanocrystalline material, and an analysis of these different methods of creation and consolidation to evaluate their applicability to mesoscale weapons applications where part features are often under 100 {micro}m wide and the material's microstructure must be very small to give homogeneous properties across the feature.

  4. A mechanistic analysis of bulk powder caking

    Science.gov (United States)

    Calvert, G.; Curcic, N.; Ghadiri, M.

    2013-06-01

    Bulk powder transformations, such as caking, can lead to numerous problems within industry when storing or processing materials. In this paper a new Environmental Caking Rig (ECR) is introduced and has been used to evaluate the caking propensity of a hygroscopic powder as a function of temperature, Relative Humidity (RH), mechanical stress and also when RH is cycled. A linear relationship exists between cake strength and the extent of bulk deformation, here defined by the engineering strain. An empirical model has been used to predict the caking behaviour based on consolidation stress and environmental conditions.

  5. Modeling of the evolution of a dislocation structure and development of microplastic deformation in single crystals of fcc substitutional solid solutions

    Science.gov (United States)

    Kulagina, V. V.; Dudarev, E. F.; Rudchenko, V. V.

    1980-07-01

    An analysis is made of evolution of a dislocation structure during the initial stage of plastic deformation and the stress-strain diagrams are derived theoretically for single crystals of fcc substitutional solid solutions. The example of Cu-Al alloys is used to confirm the theoretically predicted relationship between the stress and strain, and also between the flow stress and the resistance to the motion of a single dislocation.

  6. A one-parameter family of hamiltonian structures for the KP hierarchy and a continuous deformation of the nonlinear W[sub KP] algebra

    Energy Technology Data Exchange (ETDEWEB)

    Figueroa-O' Farrill, J.M. (Bonn Univ. (Germany). Physikalisches Inst.); Mas, J. (Santiago Univ., Santiago de Compostela (Spain). Dept. de Fisica de Particulas Elementales); Ramos, E. (Leuven Univ. (Belgium). Inst. voor Theoretische Fysica)

    1993-11-01

    The KP hierarchy is hamiltonian relative to a one-parameter family of Poisson structures obtained from a generalized Adler map in the space of formal pseudodifferential symbols with noninteger powers. The resulting W-algebra is a one-parameter deformation of W[sub KP] admitting a central extension for generic values of the parameter, reducing naturally to W[sub n] for special values of the parameter, and contracting to the centrally extended W[sub 1+[infinity

  7. A one-parameter family of hamiltonian structures for the KP hierarchy and a continuous deformation of the nonlinear W[sub KP] algebra

    Energy Technology Data Exchange (ETDEWEB)

    Figueroa-O' Farril, J.M. (Bonn Univ. (Germany). Physikalisches Inst.); Mas, J. (Universidad de Santiago de Compostela (Spain). Dept. de Fisica de Particulas Elementales); Ramos, E. (Leuven Univ. (Belgium). Inst. voor Theoretische Fysica)

    1992-07-01

    The KP hierarchy is hamiltonian relative to a one-parameter family of inequivalent Poisson structures obtained from a generalized Adler map in the space of formal pseudodifferential symbols with noninteger powers. The resulting W-algebra is a one-parameter deformation of W[sub KP] admitting a central extension for generic values of the parameter, reducing naturally to W[sub n] for special values of the parameter, and contracting to the centrally extended W[sub 1+[infinity

  8. Soft-sediment deformation structures in Late Pleistocene alluvial-aeolian sediments caused by GIA induced seismicity along the Osning Thrust (northern Germany)

    Science.gov (United States)

    Brandes, Christian; Winsemann, Jutta

    2013-04-01

    Historic sources report that northern Germany was affected by significant earthquakes during the last 500 years (Leydecker 2009), but the only modern study so far on earthquake related soft-sediment deformation structures was carried out by Hoffmann and Reicherter (2012) for the Baltic Sea coast area of northeastern Germany. We present new data on seismically triggered soft-sediment deformation structures in Pleniglacial to Late Glacial alluvial fan and aeolian sand-sheet deposits of the upper Senne (Münsterland Embayment) and link this soft-sediment deformation directly to Late Glacial earthquakes generated along the Osning Thrust, which is one of the major fault systems in Central Europe. The reactivation of the Mesozoic Osning Thrust was an effect of glacial isostatic adjustment during the Pleniglacial to Late Glacial (Brandes et al., 2012). Young tectonic activity in this area is indicated by the 1612 Bielefeld earthquake (Vogt & Grünthal 1994). The analysed soft-sediment deformation structures are exposed in two sand pits in the vicinity of the Osning Thrust and include a complex fault and fold pattern, clastic dykes, sand volcanoes, sills, irregular intrusive sedimentary bodies, flower- to antler-like dewatering structures, flame structures, and ball-and-pillow structures. There is a distinct variation of the soft-sediment deformation style parallel to the trend of the Osning Thrust. In the northwestern part of the study area, close to Oerlinghausen there is a wide range of structures developed that is mainly related to fluidization processes. In contrast, in the southeast only flower- to antler-like dewatering structures and normal fault-arrays occur. This might indicate that the epicentre of the Late Pleniglacial to Late Glacial seismic event was close to Oerlinghausen. It is the first time in northern Germany, that fluidization and liquefaction features can be directly related to a fault. The occurrence of seismicity in the Late Pleniglacial to Late

  9. Oxide or carbide nanoparticles synthesized by laser ablation of a bulk Hf target in liquids and their structural, optical, and dielectric properties

    Energy Technology Data Exchange (ETDEWEB)

    Semaltianos, N. G., E-mail: nsemaltianos@yahoo.com [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Friedt, J.-M.; Blondeau-Patissier, V.; Combe, G. [Dépt. Temps-Fréquence, Femto-st, UMR CNRS 6174, Université de Franche-Comté, Besançon 25030 (France); Chassagnon, R. [Laboratoire Interdisciplinaire Carnot De Bourgogne, ICB UMR CNRS 6303, Université de Bourgogne Franche-Comté, Dijon 21078 (France); Moutarlier, V. [UTINAM, UMR CNRS 6213, Université de Franche-Comté, Besançon 25030 (France); Assoul, M.; Monteil, G. [Dépt. Mécanique Appliquée, Femto-st, UMR CNRS 6174, Université de Franche-Comté, Besançon 25030 (France)

    2016-05-28

    Laser ablation of a bulk Hf target in deionized (DI) water, ethanol, or toluene was carried out for the production of nanoparticles' colloidal solutions. Due to the interaction of the ablation plasma plume species with the species which are produced by the liquid decomposition at the plume-liquid interface, hafnia (HfO{sub 2}) nanoparticles are synthesized in DI water, hafnium carbide (HfC) nanoparticles in toluene, and a mixture of these in ethanol. The hafnia nanoparticles are in the monoclinic low temperature phase and in the tetragonal and fcc high temperature phases. Their size distribution follows log-normal function with a median diameter in the range of 4.3–5.3 nm. Nanoparticles synthesized in DI water have band gaps of 5.6 and 5.4 eV, in ethanol 5.72 and 5.65 eV (using low and high pulse energy), and in toluene 3 eV. The values for the relative permittivity in the range of 7.74–8.90 were measured for hafnia nanoparticles' thin films deposited on substrates by drop-casting (self-assembled layers) in parallel plate capacitor structures.

  10. Structural and Mechanical Characterization of Zr58.5Ti8.2Cu14.2Ni11.4Al7.7 Bulk Metallic Glass

    Directory of Open Access Journals (Sweden)

    Jürgen Eckert

    2011-12-01

    Full Text Available Thermal stability, structure and mechanical properties of the multi-component Zr58.5Ti8.2Cu14.2Ni11.4Al7.7 bulk metallic glass have been studied in detail. The glassy material displays good thermal stability against crystallization and a fairly large supercooled liquid region of 52 K. During heating, the alloy transforms into a metastable icosahedral quasicrystalline phase in the first stage of crystallization. At high temperatures, the quasicrystalline phase undergoes a transformation to form tetragonal and cubic NiZr2-type phases. Room-temperature compression tests of the as-cast sample show good mechanical properties, namely, high compressive strength of about 1,630 MPa and fracture strain of 3.3%. This is combined with a density of 6.32 g/cm3 and values of Poisson’s ratio and Young’s modulus of 0.377 and 77 GPa, respectively. The mechanical properties of the glass can be further improved by cold rolling. The compressive strength rises to 1,780 MPa and the fracture strain increases to 8.3% for the material cold-rolled to a diameter reduction of 10%.

  11. Electronic structure in the bulk and at the surface of lanthanide materials. A detailed study with X-ray emission and inverse photoemission

    CERN Document Server

    Huebinger, F

    2000-01-01

    LaTe. With measurements of the O3-XE in the Lanthanum-Chalcogenides we could demonstrate the transfer of s-like valence electrons from the Lanthanum atom to the Chalcogen atom. Furthermore, the binding energy of the state at the Lanthanum atom was determined. The surface core-level shift is smaller by 25 % in the Chalcogenides than in La-metal. We also describe a theoretical model, which qualitatively explains the observed larger shifts of the core-level binding energy in PE than in IPE from Lanthan-Chalcogenides. This dissertation is concerned with the occupied and unoccupied electronic structure of lanthanide materials. With surface sensitive electron-excited x-ray emission spectroscopy (XES) we could experimentally determine a surface and bulk partial density of states (p-DOS) for the metals Lanthanum, Lutetium and Samarium. From calculations of the O3-XE transition probability we anticipate a three times higher probability for s-like than for d-like electrons to fill the 5p3/2-hole; this was confirmed exp...

  12. Influence of deformation on the structure and mechanical and corrosion properties of high-nitrogen austenitic 07Kh16AG13M3 steel

    Science.gov (United States)

    Berezovskaya, V. V.; Khadyev, M. S.; Merkushkin, E. A.; Sokolovskaya, Yu. A.

    2013-11-01

    The correlation has been studied between the structure of a high-nitrogen austenitic Cr-Mn-N steel formed in the process of combined hardening treatment, including cold plastic deformation (CPD), and its mechanical and corrosion properties. The structure and properties of commercial high-nitrogen (0.8% N) 07Kh16AG13M3 steel is analyzed after rolling by CPD and aging at 500 and 800°C. It is shown that CPD of the steel occurs by dislocation slip and deformation twinning. Deformation twinning and also high resistance of austenite to martensitic transformations at true strains of 0.2 and 0.4 determine the high plasticity of the steel. The contribution of the structure imperfection parameters to the broadening of the austenite lines during CPD is estimated by X-ray diffraction. The main hardening factor is stated to be lattice microdistortions. Transmission electron microscopy study shows that heating of the deformed steel to 500°C leads to the formation of the intermediate CrN phase by a homogeneous mechanism, and the intermtallic χ phase forms along the austenite grain boundaries in the case of heating at 800°C. After hardening by all investigated technological schemes, exception for aging at 800°C, the steel does not undergo pitting corrosion and is slightly prone to a stress corrosion cracking during static bending tests, while aging at 800°C causes pitting corrosion at a pitting formation potential E pf = -0.25 V.

  13. Nickel Alloy Primary Water Bulk Surface and SCC Corrosion Film Analytical Characterization and SCC Mechanistic Implications

    Energy Technology Data Exchange (ETDEWEB)

    Morton, D.; Lewis, N.; Hanson, M.; Rice, S.; Sanders, P.

    2007-04-18

    Alloy 600 corrosion coupon tests were performed: (1) to quantify the temperature dependency of general corrosion and (2) to characterize the composition and structure of bulk surface corrosion films for comparison with ongoing primary water SCC (PWSCC) crack tip corrosion film analyses. Results suggest that the thermal activation energy of Alloy 600 corrosion is consistent with the thermal activation energy of nickel alloy PWSCC. Analytical investigations of the structure and composition of Alloy 600 bulk surface corrosion oxides revealed a duplex (inner and outer) oxide layer structure. The outer layer is discontinuous and comprised of relatively large (1 to 3 {micro}m) nickel ferrite crystals and smaller ({approx}0.1 {micro}m) chromium containing nickel ferrite crystals. The inner layer consists of a relatively continuous chromite spinel (major phase) and chromia (Cr{sub 2}O{sub 3} minor phase) which formed through non-selective oxidation. Chromia and dealloyed Alloy 600 (highly Ni enriched metal) were only observed at 337 C (640 F) and only along the boundaries of deformation induced fine grains and subcells. Specimens having deformation free surfaces exhibited continuous uniform inner chromite spinel oxide layers. Specimens with machining induced surface deformation produced non-uniform inner layer oxides (chromite spinel, Cr{sub 2}O{sub 3} and unoxidized material). PWSCC crack tip oxides, in contrast, were fine grain (no duplex structure) and consisted of both chromium rich spinels and ''NiO'' structure oxides. Generally, nickel rich oxides were more abundant under more oxidized conditions (reduced coolant hydrogen) and spinel rich crack tip oxides were favored under more reducing conditions (increased coolant hydrogen). Bulk surface corrosion film thickness did not correlate with observed SCC growth rates. These results suggest that corrosion is not the rate controlling step of PWSCC but rather that PWSCC and corrosion have a common rate

  14. q-deformed Brownian motion

    CERN Document Server

    Man'ko, V I

    1993-01-01

    Brownian motion may be embedded in the Fock space of bosonic free field in one dimension.Extending this correspondence to a family of creation and annihilation operators satisfying a q-deformed algebra, the notion of q-deformation is carried from the algebra to the domain of stochastic processes.The properties of q-deformed Brownian motion, in particular its non-Gaussian nature and cumulant structure,are established.

  15. Cell wall elasticity: I. A critique of the bulk elastic modulus approach and an analysis using polymer elastic principles

    Science.gov (United States)

    Wu, H. I.; Spence, R. D.; Sharpe, P. J.; Goeschl, J. D.

    1985-01-01

    The traditional bulk elastic modulus approach to plant cell pressure-volume relations is inconsistent with its definition. The relationship between the bulk modulus and Young's modulus that forms the basis of their usual application to cell pressure-volume properties is demonstrated to be physically meaningless. The bulk modulus describes stress/strain relations of solid, homogeneous bodies undergoing small deformations, whereas the plant cell is best described as a thin-shelled, fluid-filled structure with a polymer base. Because cell walls possess a polymer structure, an alternative method of mechanical analysis is presented using polymer elasticity principles. This initial study presents the groundwork of polymer mechanics as would be applied to cell walls and discusses how the matrix and microfibrillar network induce nonlinear stress/strain relationships in the cell wall in response to turgor pressure. In subsequent studies, these concepts will be expanded to include anisotropic expansion as regulated by the microfibrillar network.

  16. Monitoring microstructural evolution in-situ during cyclic deformation by high resolution reciprocal space mapping

    DEFF Research Database (Denmark)

    Diederichs, Annika Martina; Thiel, Felix; Fischer, Torben

    2017-01-01

    is gained by in-situ monitoring of the microstructural evolution during cyclic deformation. By HRRSM, a large number of individual subgrains can be resolved within individual grains in the bulk of polycrystalline specimens and their fate, their individual orientation and elastic stresses, tracked during...... different loading regimes as tension and compression. With this technique, the evolution of dislocation structures in selected grains was followed during an individual load cycle....

  17. Internal structure, fault rocks, and inferences regarding deformation, fluid flow, and mineralization in the seismogenic Stillwater normal fault, Dixie Valley, Nevada

    Science.gov (United States)

    Caine, Jonathan S.; Bruhn, R.L.; Forster, C.B.

    2010-01-01

    Outcrop mapping and fault-rock characterization of the Stillwater normal fault zone in Dixie Valley, Nevada are used to document and interpret ancient hydrothermal fluid flow and its possible relationship to seismic deformation. The fault zone is composed of distinct structural and hydrogeological components. Previous work on the fault rocks is extended to the map scale where a distinctive fault core shows a spectrum of different fault-related breccias. These include predominantly clast-supported breccias with angular clasts that are cut by zones containing breccias with rounded clasts that are also clast supported. These are further cut by breccias that are predominantly matrix supported with angular and rounded clasts. The fault-core breccias are surrounded by a heterogeneously fractured damage zone. Breccias are bounded between major, silicified slip surfaces, forming large pod-like structures, systematically oriented with long axes parallel to slip. Matrix-supported breccias have multiply brecciated, angular and rounded clasts revealing episodic deformation and fluid flow. These breccias have a quartz-rich matrix with microcrystalline anhedral, equant, and pervasively conformable mosaic texture. The breccia pods are interpreted to have formed by decompression boiling and rapid precipitation of hydrothermal fluids whose flow was induced by coseismic, hybrid dilatant-shear deformation and hydraulic connection to a geothermal reservoir. The addition of hydrothermal silica cement localized in the core at the map scale causes fault-zone widening, local sealing, and mechanical heterogeneities that impact the evolution of the fault zone throughout the seismic cycle. ?? 2010.

  18. Full-Field Reconstruction of Structural Deformations and Loads from Measured Strain Data on a Wing Using the Inverse Finite Element Method

    Science.gov (United States)

    Miller, Eric J.; Manalo, Russel; Tessler, Alexander

    2016-01-01

    A study was undertaken to investigate the measurement of wing deformation and internal loads using measured strain data. Future aerospace vehicle research depends on the ability to accurately measure the deformation and internal loads during ground testing and in flight. The approach uses the inverse Finite Element Method (iFEM). The iFEM is a robust, computationally efficient method that is well suited for real-time measurement of real-time structural deformation and loads. The method has been validated in previous work, but has yet to be applied to a large-scale test article. This work is in preparation for an upcoming loads test of a half-span test wing in the Flight Loads Laboratory at the National Aeronautics and Space Administration Armstrong Flight Research Center (Edwards, California). The method has been implemented into an efficient MATLAB® (The MathWorks, Inc., Natick, Massachusetts) code for testing different sensor configurations. This report discusses formulation and implementation along with the preliminary results from a representative aerospace structure. The end goal is to investigate the modeling and sensor placement approach so that the best practices can be applied to future aerospace projects.

  19. Investigation of deformation of elements of three-dimensional reinforced concrete structures located in the soil, interacting with each other through rubber gaskets

    Science.gov (United States)

    Berezhnoi, D. V.; Balafendieva, I. S.; Sachenkov, A. A.; Sekaeva, L. R.

    2017-06-01

    In work the technique of calculation of elements of three-dimensional reinforced concrete substructures located in a soil, interacting with each other through rubber linings is realized. To describe the interaction of deformable structures with the ground, special “semi-infinite” finite elements are used. A technique has been implemented that allows one to describe the contact interaction of three-dimensional structures by means of a special contact finite element with specific properties. The obtained numerical results are compared with the experimental data, their good agreement is noted.

  20. Parameter Identification of Piecewise Linear Plasticity Metal Models Used in Numerical Modeling of Structures Under Plastic Deformation and Failure

    Directory of Open Access Journals (Sweden)

    A. V. Shmeliov

    2016-01-01

    Full Text Available The article describes the models of metallic materials used in the calculation of deformation and destruction of engineering structures. The reliability of material models can adequately assess the strength characteristics of the designs of new technology in its designing and certification.The article deals with contingencies and true mechanical properties of materials and presents equations of their relationship. It notes that in the software systems mechanical characteristics of materials are given in the true sense.The paper considers the linear and exponential models of materials, their characteristics, and methods to implement them. It considers the models of Johnson-Cook Steinberg-Guinan, Zerilli-Armstrong, Cowper-Symonds, Gurson-Tvergaard that take into account the strain rate and temperature of the material. Describes their applications, advantages and disadvantages. Considers single- and multi-parameter criteria of materials fracture, the prospects for their use. Gives a rational justification for using a piecewise linear plasticity material model *MAT_PIECEWISE_LINEAR_PLASTICITY (024, LS-DYNA software package for the engineering industry, and presents its main parameters.A technique to identify parameters of piecewise linear plasticity metal material models has been developed. The technique consists of the stages, based on the equations of transition from the conventional stress and strain values to the true ones. Taking into consideration the stressstrain state in the neck of the sample is a distinctive feature of the technique.Tensile tests of the round material samples have been conducted. To test the developed technique in the software package ANSYS LS-DYNA PC have been made tensile sample modeling and results comparison to show high convergence.Further improvement of the technique can be achieved through the development of a statistical approach to the analysis of the results of a series of tests. This will allow a kind of

  1. Soft sediment deformation structures in a lacustrine sedimentary succession induced by volcano-tectonic activities: An example from the Cretaceous Beolgeumri Formation, Wido Volcanics, Korea

    Science.gov (United States)

    Ko, Kyoungtae; Kim, Sung Won; Lee, Hong-Jin; Hwang, In Gul; Kim, Bok Chul; Kee, Won-Seo; Kim, Young-Seog; Gihm, Yong Sik

    2017-08-01

    The Cretaceous Beolgeumri Formation is composed of laminated mudstones intercalated with sandstones, chert, and a bed of lapilli tuff that were deposited in a lacustrine environment at the terminal part of a regional strike-slip fault systems on the southwestern Korean Peninsula. The Beolgeumri Formation contains various types of soft sediment deformation (SSD) structures that are characterized by a wide extent (morphological features and deformation styles: 1) fold structures, 2) load structures, 3) water-escape structures, 4) rip-down structures, 5) boudin structures, and 6) synsedimentary fault structures. Field examination of SSD structures together with an analysis of the sedimentological records of the Beolgeumri Formation indicate that the SSD structures formed largely by liquefaction and/or fluidization triggered by ground shaking during earthquakes. To constrain the timing of the development of SSD structures in the Beolgeumri Formation, we conducted sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon age dating of block sized lithic clasts bearing volcaniclastic deposits that conformably underlie (the Mangryeongbong Tuff) and overlie (the Ttandallae Tuff) the Beolgeumri Formation. The Mangryeongbong and Ttandallae Tuffs have ages of 86.63 ± 0.83 Ma and 87.24 ± 0.36 Ma, respectively, indicating that the Beolgeumri Formation was deposited during a short interval between major volcanic eruptions. The large lithic clasts of volcaniclastic deposits suggest that the Beolgeumri Formation was deposited adjacent to an active volcanic edifice(s). Syndepositional magmatic activities are suggested by the occurrence of a lapilli tuff bed in the Beolgeumri Formation and an igneous intrusion (intermediate sill) that is crosscut by a sand dike, as well as the similar age results of the underlying and overlying volcaniclastic deposits. Thus, we infer that the earthquakes that caused the development of SSD structures in the study area were closely related to

  2. STRUCTURE OF THE LITHOSPHERE AND SEISMOTECTONIC DEFORMATIONS IN CONTACT ZONE OF LITHOSPHERIC PLATES IN THE SUMATRA ISLAND REGION

    Directory of Open Access Journals (Sweden)

    O. A. Kuchay

    2015-09-01

    Full Text Available The inversion seismic tomography algorithm (ITS was used to calculate 3D seismic anomalies models for velocities of P- and S-waves in the zone of the Sunda arc, Indonesia. In the area under study, strong earthquakes (M>4.8 are clustered in the zone of high P-wave velocities. Earthquake hypocenters are located in zones of both high and low velocity anomalies of S-waves. The giant Sumatra earthquake (December 26, 2004, Mw=9.0 ruptured the greatest fault length of any recorded earthquake, and the rupture started in the area wherein the sign of P-wave velo­city anomalies is abruptly changed. We calculated seismotectonic deformations (STD from data on mechanisms of 2227 earthquakes recorded from 1977 to 2013, and our calculations show that the STD component, that controls vertical extension of rocks, is most stable through all the depth levels. In the marginal regions at the western and eastern sides of the Sunda arc, the crustal areas (depths from 0 to 35 km are subject to deformations which sign is opposite to that of deformations in the central part. Besides, at depths from 70 to 150 km beneath the Sumatra earthquake epicentre area, the zone is subject to deformations which sign is opposite to that of deformations in the studied part of the Sunda arc. For earthquakes that may occur in the crust in the Sunda arc in the contact zone of the plates, maximum magnitudes depend on the direction of pressure imposed by the actively subducting plate, which is an additional criteria for determining the limit magnitude for the region under study. 

  3. Soft-sediment deformation structures related to volcanic earthquakes of the Lower Cretaceous Qingshan Group in Lingshan Island, Shandong Province, East China

    Directory of Open Access Journals (Sweden)

    Yao-Qi Zhou

    2017-04-01

    The SSDS types in the Qingshan Group includes load and flame structure, ball and pillow structure, water-escape structure, hydroplastic deformation structure, plastic sandstone breccia structure, volcanic drop stone and V-shaped ground fissure mainly caused by volcanic earthquakes of three types: (1 seismic waves, (2 gravity and inertia effect of pyroclastic flows, (3 instant differential air pressure; which is different from slumping and tectonic earthquakes occurred in the Laiyang Group. In addition, with the lithofacies association analysis between pyroclastic flow and SSDS beds, a distribution model of SSDS related to volcanic earthquakes can be established: SSDS types changed gradually with their distance further away from the volcanic activity core. Brittle deformation which was common in the proximal zone disappeared gradually; liquefied and plastic SSDS continued to dominate in the medial zone; and slightly liquefied SSDS were developed in the distal zone. Meanwhile, the scale and size of SSDS is negatively correlated with the distance of SSDS depositional locations from the volcanic vent.

  4. Deformation due to contact between a rough surface and a smooth ball

    NARCIS (Netherlands)

    Jamari, Jamari; Schipper, Dirk J.

    2007-01-01

    Theoretical and experimental results are presented to evaluate the deformation behavior of the contact between a real rough flat surface and a smooth ball. There are three deformation responses: plastic deformation of the asperities only, plastic deformation of the bulk only and combined plastic

  5. Fraktalnist deformational relief polycrystalline aluminum

    Directory of Open Access Journals (Sweden)

    М.В. Карускевич

    2006-02-01

    Full Text Available  The possibility of the fractal geometry method application for the analisys of surface deformation structures under cyclic loading is presented.It is shown, that deformation relief of the alclad aluminium alloyes meets the criteria of the fractality. For the fractal demention estimation the method of  “box-counting”can be applied.

  6. The Effect of Molecular Structure and Environment on the Miscibility and Diffusivity in Polythiophene-Methanofullerene Bulk Heterojunctions: Theory and Modeling with the RISM Approach

    Directory of Open Access Journals (Sweden)

    Alexander E. Kobryn

    2016-04-01

    Full Text Available Although better means to model the properties of bulk heterojunction molecular blends are much needed in the field of organic optoelectronics, only a small subset of methods based on molecular dynamics- and Monte Carlo-based approaches have been hitherto employed to guide or replace empirical characterization and testing. Here, we present the first use of the integral equation theory of molecular liquids in modelling the structural properties of blends of phenyl-C61-butyric acid methyl ester (PCBM with poly(3-hexylthiophene (P3HT and a carboxylated poly(3-butylthiophene (P3BT, respectively. For this, we use the Reference Interaction Site Model (RISM with the Universal Force Field (UFF to compute the microscopic structure of blends and obtain insight into the miscibility of its components. Input parameters for RISM, such as optimized molecular geometries and charge distribution of interaction sites, are derived by the Density Functional Theory (DFT methods. We also run Molecular Dynamics (MD simulation to compare the diffusivity of the PCBM in binary blends with P3HT and P3BT, respectively. A remarkably good agreement with available experimental data and results of alternative modelling/simulation is observed for PCBM in the P3HT system. We interpret this as a step in the validation of the use of our approach for organic photovoltaics and support of its results for new systems that do not have reference data for comparison or calibration. In particular, for the less-studied P3BT, our results show that expectations about its performance in binary blends with PCBM may be overestimated, as it does not demonstrate the required level of miscibility and short-range structural organization. In addition, the simulated mobility of PCBM in P3BT is somewhat higher than what is expected for polymer blends and falls into a range typical for fluids. The significance of our predictive multi-scale modelling lies in the insights it offers into nanoscale

  7. The Ionian Abyssal Plain - closure of a remnant Mesozoic oceanic domain: subbottom structures, deep deformation and the Calabrian subduction zone

    Science.gov (United States)

    Gallais, F.; Gutscher, M.; Graindorge, D.; Klaeschen, D.

    2010-12-01

    rheology of the Messinian salts acts as the décollement level in the frontal part of the wedge. Repeated imbricate thrusting within in the Calabrian wedge allows the thickening of the Messinian sediments from 1200 m beneath the IAP to 2400 m 30 km away from the deformation front. A major tectonic structure is imaged east of the Malta Escarpment by the Archimede profiles, it offsets the top Pre-Messinian deposits by 0.5 - 1 sTWT increasing from S to N. This N150°E oriented lithospheric fault is interpreted as a tear fault (“STEP” fault) which has allowed the roll-back of the Ionian slab. The activity of these faults and the Calabrian and Mediterranean subduction zones have been reconstructed through time to reach the present-day physiology of the remnant Ionian basin. The analysis of their activity will allow a better understanding of the closure of the Ionian domain.

  8. Geometrically nonlinear deformation and the emergent behavior of polarons in soft matter.

    Science.gov (United States)

    Li, Xiaobao; Liu, Liping; Sharma, Pradeep

    2015-11-07

    Mechanical strain can alter the electronic structure of both bulk semiconductors as well as nanostructures such as quantum dots. This fact has been extensively researched and exploited for tailoring electronic properties. The strain mediated interaction between the charge carriers and the lattice is interpreted through the so-called deformation potential. In the case of soft materials or nanostructures, such as DNA, the deformation potential leads to the formation of polarons which largely determine the electronic characteristics of DNA and similar polymer entities. In addition, polarons are also speculated to be responsible for the mechanism of quantum actuation in carbon nanotubes. The deformation potential is usually taken to be a linear function of the lattice deformation (U ∼ αε) where α is the deformation potential "constant" that determines the coupling strength and ε is the mechanical strain. In this letter, by carefully accounting for nonlinear geometric deformation that has been hitherto ignored so far in this context, we show that the deformation potential constant is renormalized in a non-trivial manner and is hardly a constant. It varies spatially within the material and with the size of the material. This effect, while negligible for hard materials, is found to be important for soft materials and critically impacts the interpretation of quantities such as polaron size, binding energy, and accordingly, electronic behavior.

  9. 4-D crustal structure of the conterminous U.S.: Continental assembly, crustal growth, and deformation history from receiver functions, xenoliths, and structural mapping

    Science.gov (United States)

    Schulte-Pelkum, V.; Mahan, K. H.

    2015-12-01

    We investigate seismic and geological features related to the tectonic evolution of the crust on a continent-wide scale. We present continent-wide features using Transportable Array data receiver function analysis, followed by regional comparisons to tie to ground truth from xenolith studies and structural mapping. We stress that the Transportable Array, at ~75 km station spacing, only offers a collection of point measurements of the crust due to the lack of crossing raypaths. 7.x layers (lower crust with high seismic velocities) can be created during crustal growth processes such as magmatic or mechanical underplating and during crustal modification such as large-scale melting. We present receiver function results and a compilation of previous regional studies using refraction data or receiver functions from regional dense networks. 7.x layers appear predominantly in parts of the northern U.S. Cordillera and across the southeastern U.S. We compare the seismic results with a xenolith study in Montana that details incremental growth of the 7.x layer from the Archean on. Hydration of a granulitic lower crust can destroy the 7.x layer and has the potential to cause epirogenic uplift. We interpret the pattern seen across the Transportable Array in the light of this hypothesis. Ductile deformation of the deep crust generates shear fabrics that can be detected seismically. Receiver functions detect shear zones via contrasts in foliation to the surrounding material. We map foliation strikes and depths in the crust across the Transportable Array using azimuthal analysis of receiver functions. Strikes from receiver functions typically align with surface fault traces in tectonically active regions, with depths of the converters exceeding the brittle zone. We discuss continent-wide strikes mapped with receiver functions. Contrasting orientations of Proterozoic shear zones and pervasive surrounding foliations in basement exposures in Colorado are reflected in seismic results

  10. Influence of cross-link structure, density and mechanical properties in the mesoscale deformation mechanisms of collagen fibrils

    Science.gov (United States)

    Depalle, Baptiste; Qin, Zhao; Shefelbine, Sandra J.; Buehler, Markus J.

    2015-01-01

    Collagen is a ubiquitous protein with remarkable mechanical properties. It is highly elastic, shows large fracture strength and enables substantial energy dissipation during deformation. Most of the connective tissue in humans consists of collagen fibrils composed of a staggered array of tropocollagen molecules, which are connected by intermolecular cross-links. In this study, we report a three-dimensional coarse-grained model of collagen and analyze the influence of enzymatic cross-links on the mechanics of collagen fibrils. Two representatives immature and mature cross-links are implemented in the mesoscale model using a bottom-up approach. By varying the number, type and mechanical properties of cross-links in the fibrils and performing tensile test on the models, we systematically investigate the deformation mechanisms of cross-linked collagen fibrils. We find that cross-linked fibrils exhibit a three phase behavior, which agrees closer with experimental results than what was obtained using previous models. The fibril mechanical response is characterized by: (i) an initial elastic deformation corresponding to the collagen molecule uncoiling, (ii) a linear regime dominated by molecule sliding and (iii) the second stiffer elastic regime related to the stretching of the backbone of the tropocollagen molecules until the fibril ruptures. Our results suggest that both cross-link density and type dictate the stiffness of large deformation regime by increasing the number of interconnected molecules while cross-links mechanical properties determine the failure strain and strength of the fibril. These findings reveal that cross-links play an essential role in creating an interconnected fibrillar material of tunable toughness and strength. PMID:25153614

  11. Estimating 4D-CBCT from prior information and extremely limited angle projections using structural PCA and weighted free-form deformation for lung radiotherapy.

    Science.gov (United States)

    Harris, Wendy; Zhang, You; Yin, Fang-Fang; Ren, Lei

    2017-03-01

    To investigate the feasibility of using structural-based principal component analysis (PCA) motion-modeling and weighted free-form deformation to estimate on-board 4D-CBCT using prior information and extremely limited angle projections for potential 4D target verification of lung radiotherapy. A technique for lung 4D-CBCT reconstruction has been previously developed using a deformation field map (DFM)-based strategy. In the previous method, each phase of the 4D-CBCT was generated by deforming a prior CT volume. The DFM was solved by a motion model extracted by a global PCA and free-form deformation (GMM-FD) technique, using a data fidelity constraint and deformation energy minimization. In this study, a new structural PCA method was developed to build a structural motion model (SMM) by accounting for potential relative motion pattern changes between different anatomical structures from simulation to treatment. The motion model extracted from planning 4DCT was divided into two structures: tumor and body excluding tumor, and the parameters of both structures were optimized together. Weighted free-form deformation (WFD) was employed afterwards to introduce flexibility in adjusting the weightings of different structures in the data fidelity constraint based on clinical interests. XCAT (computerized patient model) simulation with a 30 mm diameter lesion was simulated with various anatomical and respiratory changes from planning 4D-CT to on-board volume to evaluate the method. The estimation accuracy was evaluated by the volume percent difference (VPD)/center-of-mass-shift (COMS) between lesions in the estimated and "ground-truth" on-board 4D-CBCT. Different on-board projection acquisition scenarios and projection noise levels were simulated to investigate their effects on the estimation accuracy. The method was also evaluated against three lung patients. The SMM-WFD method achieved substantially better accuracy than the GMM-FD method for CBCT estimation using extremely

  12. Bulk Nanolaminated Nickel: Preparation, Microstructure, Mechanical Property, and Thermal Stability

    Science.gov (United States)

    Liu, Fan; Yuan, Hao; Goel, Sunkulp; Liu, Ying; Wang, Jing Tao

    2018-02-01

    A bulk nanolaminated (NL) structure with distinctive fractions of low- and high-angle grain boundaries ( f LAGBs and f HAGBs) is produced in pure nickel, through a two-step process of primary grain refinement by equal-channel angular pressing (ECAP), followed by a secondary geometrical refinement via liquid nitrogen rolling (LNR). The lamellar boundary spacings of 2N and 4N nickel are refined to 40 and 70 nm, respectively, and the yield strength of the NL structure in 2N nickel reaches 1.5 GPa. The impacts of the deformation path, material purity, grain boundary (GB) misorientation, and energy on the microstructure, refinement ability, mechanical strength, and thermal stability are investigated to understand the inherent governing mechanisms. GB migration is the main restoration mechanism limiting the refinement of an NL structure in 4N nickel, while in 2N nickel, shear banding occurs and mediates one-fifth of the total true normal rolling strain at the mesoscale, restricting further refinement. Three typical structures [ultrafine grained (UFG), NL with low f LAGBs, and NL with high f LAGBs] obtained through three different combinations of ECAP and LNR were studied by isochronal annealing for 1 hour at temperatures ranging from 433 K to 973 K (160 °C to 700 °C). Higher thermal stability in the NL structure with high f LAGBs is shown by a 50 K (50 °C) delay in the initiation temperature of recrystallization. Based on calculations and analyses of the stored energies of deformed structures from strain distribution, as characterized by kernel average misorientation (KAM), and from GB misorientations, higher thermal stability is attributed to high f LAGBs in this type of NL structure. This is confirmed by a slower change in the microstructure, as revealed by characterizing its annealing kinetics using KAM maps.

  13. Bulk Nanolaminated Nickel: Preparation, Microstructure, Mechanical Property, and Thermal Stability

    Science.gov (United States)

    Liu, Fan; Yuan, Hao; Goel, Sunkulp; Liu, Ying; Wang, Jing Tao

    2017-11-01

    A bulk nanolaminated (NL) structure with distinctive fractions of low- and high-angle grain boundaries (f LAGBs and f HAGBs) is produced in pure nickel, through a two-step process of primary grain refinement by equal-channel angular pressing (ECAP), followed by a secondary geometrical refinement via liquid nitrogen rolling (LNR). The lamellar boundary spacings of 2N and 4N nickel are refined to 40 and 70 nm, respectively, and the yield strength of the NL structure in 2N nickel reaches 1.5 GPa. The impacts of the deformation path, material purity, grain boundary (GB) misorientation, and energy on the microstructure, refinement ability, mechanical strength, and thermal stability are investigated to understand the inherent governing mechanisms. GB migration is the main restoration mechanism limiting the refinement of an NL structure in 4N nickel, while in 2N nickel, shear banding occurs and mediates one-fifth of the total true normal rolling strain at the mesoscale, restricting further refinement. Three typical structures [ultrafine grained (UFG), NL with low f LAGBs, and NL with high f LAGBs] obtained through three different combinations of ECAP and LNR were studied by isochronal annealing for 1 hour at temperatures ranging from 433 K to 973 K (160 °C to 700 °C). Higher thermal stability in the NL structure with high f LAGBs is shown by a 50 K (50 °C) delay in the initiation temperature of recrystallization. Based on calculations and analyses of the stored energies of deformed structures from strain distribution, as characterized by kernel average misorientation (KAM), and from GB misorientations, higher thermal stability is attributed to high f LAGBs in this type of NL structure. This is confirmed by a slower change in the microstructure, as revealed by characterizing its annealing kinetics using KAM maps.

  14. Effect of deformation on the electronic structure and topological properties of the AIIMg2Bi2 (AII = Mg,Ca,Sr,Ba) compounds

    Science.gov (United States)

    Petrov, E. K.; Silkin, I. V.; Koroteev, Yu. M.; Chulkov, E. V.

    2017-04-01

    The electronic structure and topological properties of the AIIMg2Bi2 (AII = Mg,Ca,Sr,Ba) compounds are theoretically studied with the use of exact exchange. It is found that the Mg3Bi2 compound in the equilibrium state is a semimetal, whereas three other compounds are semiconductors with a direct fundamental band gap. It is predicted that the uniaxial deformation of three-component compounds results in transitions to topologically nontrivial phases: topological insulator and topological and Dirac semimetals. Owing to such a rich variety of topologically nontrivial phases, these compounds may be of interest for further theoretical and experimental studies.

  15. Effect of various kinds of severe plastic deformation on the structure and electromechanical properties of precipitation-strengthened CuCrZr alloy

    Science.gov (United States)

    Belyaeva, A. I.; Galuza, A. A.; Khaimovich, P. A.; Kolenov, I. V.; Savchenko, A. A.; Solodovchenko, S. I.; Shul'gin, N. A.

    2016-11-01

    The effect of various kinds of severe plastic deformation (equal-channel angular pressing and quasi-hydrostatic extrusion at 77 and 300 K) on the structural formation of precipitation-strengthened CuCrZr alloy has been studied. A combination of experimental methods has been used. Sputtering by deuterium ions was used as the tool for the layer-by-layer study of the alloy structure. The difference between the sputtering yields of the matrix (copper) and precipitates (Cr and Zr) allowed us to visualize the alloy structure to a total depth of 0.5-1 μm. The effect of severe plastic deformation on the precipitate distribution is considered. It has been shown that the main peculiarity of the microstructure is related to the high density of precipitates enriched in chromium, which completely determine the surface roughness. Their distribution is not related to the grain size. The combination of equal-channel angular pressing and quasi-hydrostatic extrusion was shown to lead to the increase in the microhardness of the CuCrZr alloy to 2300 MPa in the case of low-temperature quasi-hydrostatic extrusion (at 77 K) and to the retained high conductivity. It has been proved that the high anisotropy of precipitate shape, microhardness, and sputtering yield of the CuCrZr alloy is determined by equal-channel angular pressing.

  16. Formation and Mechanical Properties of Pd-Si Binary Bulk Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Na Chen

    2014-01-01

    Full Text Available Glassy spherical samples in the diameters up to 10 mm were produced in a binary Pd-Si alloy system. These Pd-Si bulk metallic glasses (BMGs combine high strength of about 1600 MPa and superplasticity of over 70% together. In addition to abundant micrometer-scale shear bands, 10–20 nanometer-sized shear bands were also observed on the side surface of the deformed sample. The excellent ductility shown by the Pd-Si BMGs is suggested to arise from the nanoscale structural inhomogeneity.

  17. Deformations of the Almheiri-Polchinski model

    Energy Technology Data Exchange (ETDEWEB)

    Kyono, Hideki; Okumura, Suguru; Yoshida, Kentaroh [Department of Physics, Kyoto University, Kitashirakawa Oiwake-cho, Kyoto 606-8502 (Japan)

    2017-03-31

    We study deformations of the Almheiri-Polchinski (AP) model by employing the Yang-Baxter deformation technique. The general deformed AdS{sub 2} metric becomes a solution of a deformed AP model. In particular, the dilaton potential is deformed from a simple quadratic form to a hyperbolic function-type potential similarly to integrable deformations. A specific solution is a deformed black hole solution. Because the deformation makes the spacetime structure around the boundary change drastically and a new naked singularity appears, the holographic interpretation is far from trivial. The Hawking temperature is the same as the undeformed case but the Bekenstein-Hawking entropy is modified due to the deformation. This entropy can also be reproduced by evaluating the renormalized stress tensor with an appropriate counter-term on the regularized screen close to the singularity.

  18. XPS-and-DFT analyses of the Pb 4f — Zn 3s and Pb 5d — O 2s overlapped ambiguity contributions to the final electronic structure of bulk and thin-film Pb-modulated zincite

    Energy Technology Data Exchange (ETDEWEB)

    Zatsepin, D.A. [M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 620990 Yekaterinburg (Russian Federation); Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation); Boukhvalov, D.W., E-mail: danil@hanyang.ac.kr [Department of Chemistry, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Theoretical Physics and Applied Mathematics Department, Ural Federal University,Mira Street 19, 620002 Yekaterinburg (Russian Federation); Gavrilov, N.V. [Institute of Electrophysics, Russian Academy of Sciences, Ural Branch, 620990 Yekaterinburg (Russian Federation); Kurmaev, E.Z. [M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 620990 Yekaterinburg (Russian Federation); Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation); Zatsepin, A.F. [Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation); Cui, L. [Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Shur, V. Ya.; Esin, A.A. [Institute of Natural Sciences, Ural Federal University, 51 Lenin Ave, 620000 Yekaterinburg (Russian Federation)

    2017-05-31

    Highlights: • Two modes of ZnO:Pb in the bulk and surface morphologies were established: the high- and low-interaction. • It was shown the ambiguity contribution of Pb 4f − Zn 3s and Pb 5d − O 2s states into final electronic structure. • The main type of defects is PbO-like with some PbO{sub 2}-like contributions. • An applied wurzite-like structural model well agrees with experimental data obtained for zincite. - Abstract: The electronic structures of zincite Pb-modulated bulk and thin-films were studied via X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) techniques. Both XPS data and DFT-calculations allowed the derivation of two different Pb-embedding scenarios into the ZnO-hosts. These included the high-interaction mode of Pb-impurity with initial zinc-oxygen host-lattice for the bulk morphology, accompanied with low Pb-metal losses; and the low-interaction mode for thin-films, where there was intake of Pb-impurities into the hollows of the surface. Despite dissimilar mechanisms of Pb-impurity accumulation and distribution in the bulk and thin-films zincite host-matrices, the strong Pb 4f — Zn 3s and Pb 5d — O 2s overlapped ambiguity contribution to the appropriate core-level structure and valence bands was established by XPS analysis and reproduced with the help of DFT-calculations. It was shown that the microscopic structure of the embedded lead-impurity played a crucial role in the Pb ion-beam stimulated synthesis of secondary lead-oxygen phases via large-area defect fabrication, and the difference among zincite and wurzite polymorphs played almost no role in this case.

  19. 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

    1997-01-01

    The phase behavior of a low molecular weight (M-w = 6000) symmetric triblock copolymer of poly(ethylene oxide) and poly(isobutylene), PEO-PIB-PEO, in the bulk as well in aqueous, D2O, solutions has been studied using small-angle neutron scattering and cryo-transmission electron microscopy...

  20. Structural, chemical, and thermoelectric properties of Bi{sub 2}Te{sub 3} Peltier materials. Bulk, thin films, and superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Peranio, Nicola

    2008-07-01

    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 Bi{sub 2}Te{sub 3} and in compounds with similar structural and chemical microstructures. This work can be subdivided as follows: (I) N-type Bi{sub 2}(Te{sub 0.91}Se{sub 0.09}){sub 3} and p-type (Bi{sub 0.26}Sb{sub 0.74}){sub 1.98}(Te{sub 0.99}Se{sub 0.01}){sub 3.02} bulk materials synthesised by the Bridgman technique. (II) Bi{sub 2}Te{sub 3} thin films and Bi{sub 2}Te{sub 3}/Bi{sub 2}(Te{sub 0.88}Se{sub 0.12}){sub 3} superlattices epitaxially grown by molecular beam epitaxy (MBE) on BaF{sub 2} substrates with periods of {delta}-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 <5,-5,1> and an amplitude of about 10 pm and (ii) a wave vector parallel to {l_brace}1,0,10{r_brace} 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.)

  1. WE-AB-BRA-08: Results of a Multi-Institutional Study for the Evaluation of Deformable Image Registration Algorithms for Structure Delineation Via Computational Phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Loi, G; Fusella, M [University Hospital “Maggiore della Carita”, Novara (Italy); Fiandra, C [University of Torino, Turin (Italy); Lanzi, E [G. Mazzini Hospital, Teramo (Italy); Rosica, A [Regina Elena National Cancer Institute, Rome (Italy); Strigari, L [Centro Oncologico Fiorentino, Florence (Italy); Orlandini, L [A.O. Ordine Mauriziano di Torino, Turin (Italy); Gino, E [Istituto Oncologico Veneto IOV, Padova (Italy); Roggio, A [Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, Meldola (Italy); Marcocci, F [ARNAS Civico - Di Cristina - Benfratelli, Palermo (Italy); Iacovello, G; Miceli, R [Tor Vergata University General Hospital, Rome (Italy)

    2015-06-15

    Purpose: To investigate the accuracy of various algorithms for deformable image registration (DIR), to propagate regions of interest (ROIs) in computational phantoms based on patient images using different commercial systems. This work is part of an Italian multi-institutional study to test on common datasets the accuracy, reproducibility and safety of DIR applications in Adaptive Radiotherapy. Methods: Eleven institutions with three available commercial solutions provided data to assess the agreement of DIR-propagated ROIs with automatically drown ROIs considered as ground-truth for the comparison. The DIR algorithms were tested on real patient data from three different anatomical districts: head and neck, thorax and pelvis. For every dataset two specific Deformation Vector Fields (DVFs) provided by ImSimQA software were applied to the reference data set. Three different commercial software were used in this study: RayStation, Velocity and Mirada. The DIR-mapped ROIs were then compared with the reference ROIs using the Jaccard Conformity Index (JCI). Results: More than 600 DIR-mapped ROIs were analyzed. Putting together all JCI data of all institutions for the first DVF, the mean JCI was 0.87 ± 0.7 (1 SD) while for the second DVF JCI was 0.8 ± 0.13 (1 SD). Several considerations on different structures are available from collected data: the standard deviation among different institutions on specific structure raise as the larger is the applied DVF. The higher value is 10% for bladder. Conclusion: Although the complexity of deformation of human body is very difficult to model, this work illustrates some clinical scenarios with well-known DVFs provided by specific software. CI parameter gives the inter-user variability and may put in evidence the need of improving the working protocol in order to reduce the inter-institution JCI variability.

  2. Applications of Displacement Transfer Functions to Deformed Shape Predictions of the G-III Swept-Wing Structure

    Science.gov (United States)

    Lung, Shun-Fat; Ko, William L.

    2016-01-01

    In support of the Adaptive Compliant Trailing Edge [ACTE] project at the NASA Armstrong Flight Research Center, displacement transfer functions were applied to the swept wing of a Gulfstream G-III airplane (Gulfstream Aerospace Corporation, Savannah, Georgia) to obtain deformed shape predictions. Four strainsensing lines (two on the lower surface, two on the upper surface) were used to calculate the deformed shape of the G III wing under bending and torsion. There being an insufficient number of surface strain sensors, the existing G III wing box finite element model was used to generate simulated surface strains for input to the displacement transfer functions. The resulting predicted deflections have good correlation with the finite-element generated deflections as well as the measured deflections from the ground load calibration test. The convergence study showed that the displacement prediction error at the G III wing tip can be reduced by increasing the number of strain stations (for each strain-sensing line) down to a minimum error of l.6 percent at 17 strain stations; using more than 17 strain stations yielded no benefit because the error slightly increased to 1.9% when 32 strain stations were used.

  3. Determining relative bulk viscosity of kilometre-scale crustal units using field observations and numerical modelling

    Science.gov (United States)

    Gardner, Robyn L.; Piazolo, Sandra; Daczko, Nathan R.

    2017-11-01

    Though the rheology of kilometre-scale polymineralic rock units is crucial for reliable large-scale, geotectonic models, this information is difficult to obtain. In geotectonic models, a layer is defined as an entity at the kilometre scale, even though it is heterogeneous at the millimetre to metre scale. Here, we use the shape characteristics of the boundaries between rock units to derive the relative bulk viscosity of those units at the kilometre scale. We examine the shape of a vertically oriented ultramafic, harzburgitic-lherzolitic unit, which developed a kilometre-scale pinch and swell structure at mid-crustal conditions ( 600 °C, 8.5 kbar), in the Anita Shear Zone, New Zealand. The ultramafic layer is embedded between a typical polymineralic paragneiss to the west, and a feldspar-quartz-hornblende orthogneiss, to the east. Notably, the boundaries on either side of the ultramafic layer give the ultramafics an asymmetric shape. Microstructural analysis shows that deformation was dominated by dislocation creep (n = 3). Based on the inferred rheological behaviour from the field, a series of numerical simulations are performed. Relative and absolute values are derived for bulk viscosity of the rock units by comparing boundary tortuosity difference measured on the field example and the numerical series. Our analysis shows that during deformation at mid-crustal conditions, paragneisses can be 30 times less viscous than an ultramafic unit, whereas orthogneisses have intermediate viscosity, 3 times greater than the paragneisses. If we assume a strain rate of 10- 14 s- 1 the ultramafic, orthogneiss and paragneiss have syn-deformational viscosities of 3 × 1022, 2.3 × 1021 and 9.4 × 1020 Pa s, respectively. Our study shows pinch and swell structures are useful as a gauge to assess relative bulk viscosity of rock units based on shape characteristics at the kilometre scale and in non-Newtonian flow regimes, even where heterogeneity occurs within the units at the

  4. Structural and temporal evolution of a reactivated brittle-ductile fault - Part I: Fault architecture, strain localization mechanisms and deformation history

    Science.gov (United States)

    Torgersen, E.; Viola, G.

    2014-12-01

    Faults are by nature dynamic, as their architecture and composition evolve progressively in space and through time steered by the interplay between strain weakening and hardening mechanisms. This study combines structural analysis, geochemistry and chlorite geothermometry to investigate deformation and strain localization mechanisms of the Kvenklubben fault, a Paleozoic brittle-ductile thrust in northern Norway, with the goal to constrain their temporal variations and the consequences thereof on fault architecture development and rheological behavior. The fault evolved from an initially discrete brittle feature slipping mainly by seismogenic ruptures to a wide brittle-ductile phyllonite deforming by aseismic creep. The formation of mechanically weak phyllosilicates by decarbonation of footwall dolostones and carbonation of hanging wall metabasalts was the main weakening mechanism, whereas partitioning of fluid flow and fracture sealing following transient high pore pressure-driven embrittlement caused episodic and localized strain hardening. The interplay between strain weakening and hardening mechanisms caused the fault core to widen. We suggest that the ability for carbonate-hosted faults to slip by seismogenic rupture is also a function of the faults' structural-evolutionary stage, and that it decreases progressively with fault maturity. This study demonstrates the importance of calibrating the present-day fault anatomy against the dynamic character of faults, which evolve geometrically, compositionally and mechanically in space and through time.

  5. Quantitative assessment of foot structure in rheumatoid arthritis by a foot digitizer: detection of deformities even in the absence of erosions.

    Science.gov (United States)

    De Mits, Sophie; Mielants, Herman; De Clercq, Dirk; Woodburn, James; Roosen, Philip; Elewaut, Dirk

    2012-11-01

    Foot involvement is a major feature in rheumatoid arthritis (RA), leading to structural deformities. Methods to allow a 3-dimensional (3-D) evaluation of foot structure in RA to be applicable in daily clinical practice have not been evaluated. This study assessed the use of a foot digitizer, a noninvasive 3-D scanner collecting objective quantitative data of the feet, to evaluate the presence of foot structure abnormalities in an RA outpatient cohort. Foot digitizer data of RA patients were compared with healthy controls. Subanalyses were performed to find relationships with erosive disease and the presence of swollen and/or tender joints. Linear mixed models were applied with correction, including sex, age, body weight and height, foot length, Disease Activity Score in 28 joints, and disease duration. Forty-one percent of the patients showed >1 abnormal parameter, measured with the 3-D foot scanner. Most differences found were located in the forefoot, the most frequently affected area of the RA foot. Strikingly, even in the absence of joint erosions, marked alterations were found. Comparable differences were also observed between the patients with and without swollen and/or tender joints. Additionally, alterations were not strongly related to foot pain and disability, suggesting the capacity of the foot digitizer to detect early changes in foot structure. The results highlight the impact of RA on foot structure, even in the absence of clinical signs of swelling or radiographic erosions. The foot digitizer offers a valuable tool to screen for such foot deformities before the presence of erosions. Copyright © 2012 by the American College of Rheumatology.

  6. Stress-Corrosion Interactions in Zr-Based Bulk Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Petre Flaviu Gostin

    2015-07-01

    Full Text Available Stress-corrosion interactions in materials may lead to early unpredictable catastrophic failure of structural parts, which can have dramatic effects. In Zr-based bulk metallic glasses, such interactions are particularly important as these have very high yield strength, limited ductility, and are relatively susceptible to localized corrosion in halide-containing aqueous environments. Relevant features of the mechanical and corrosion behavior of Zr-based bulk metallic glasses are described, and an account of knowledge regarding corrosion-deformation interactions gathered from ex situ experimental procedures is provided. Subsequently the literature on key phenomena including hydrogen damage, stress corrosion cracking, and corrosion fatigue is reviewed. Critical factors for such phenomena will be highlighted. The review also presents an outlook for the topic.

  7. Record of continental to marine transition from the Mesoproterozoic Ampani basin, Central India: An exercise of process-based sedimentology in a structurally deformed basin

    Science.gov (United States)

    Chakraborty, Partha Pratim; Saha, Subhojit; Das, Kaushik

    2017-08-01

    The Mesoproterozoic Ampani Group of rocks, a structurally deformed sedimentary package hosted within the Bastar Craton in central India, was studied for process-based facies and paleoenvironmental analyses. Outcrop mapping on 1:1500 scale, deconvolution of deformation pattern, and process-based facies analyses have led to the identification of fifteen facies types, clubbed under four facies associations. A range of paleoenvironmental settings varying from continental fluvial to distal marine shelf is inferred. Deductive paleohydrology revealed poorly-efficient 'dirty river' character for the Ampani River system with low water discharge. However, at times of catastrophic sheet floods release of sediments trapped at the river mouth in form of hyperpycnal underflows triggered formation of river mouth delta. Reworking of delta front sediment in wave-dominated coastline resulted development of beach-foreshore and shoreface (proximal to distal). Variation in the relative proportion of bar and interbar products within the shoreface successions exposed at different studied sections is interpreted as signature of relative bathymetric variation. The pro-deltaic Ampani shelf was storm infested. Tectonic perturbance in the basin hinterland in course of Ampani sedimentation is inferred from occurrence of a disparately thick lobate high-density flow deposit towards the top of shoreface succession and increase in feldspar content upward within the shoreface succession. Addition of detritus from a ∼1600 Ma Mesoproterozoic provenance in upper part of shoreface also strengthen the contention. Deconvolution of deformation pattern and delineation of environmental products ranging between continental and deep marine allowed us to infer the Ampani sediment package as fining-upward in character evolved in a transgressive mode.

  8. Large scale deformation in a locked collisional boundary: Interplay between subsidence and uplift, intraplate stress and inherited lithospheric structure in the late stage of the SE Carpathians evolution.

    NARCIS (Netherlands)

    Matenco, L.C.; Bertotti, G.V.; Leever, K.A.; Cloetingh, S.A.P.L.; Schmid, S.; Tarapoanca, M.; Dinu, C.

    2007-01-01

    The interplay between slab dynamics and intraplate stresses in postcollisional times creates large near-surface deformation, particularly in highly bent orogens with significant lateral variations in mechanical properties. This deformation is expressed through abnormal foredeep geometries and

  9. Fiber optic monitoring methods for composite steel-concrete structures based on determination of neutral axis and deformed shape.

    Science.gov (United States)

    2014-01-01

    Structural Health Monitoring has great potential to provide valuable information about the actual structural condition and can help optimize the management activities. However, few effective and robust monitoring methods exist which hinders a nationw...

  10. Evolution of the structure and mechanical properties of a bulk-nitrided corrosion-resistant ferritic steel upon tempering in the temperature range of 400-700°C

    Science.gov (United States)

    Rogachev, S. O.; Nikulin, S. A.; Khatkevich, V. M.

    2017-08-01

    Methods of the X-ray diffraction analysis and electron microscopy were used to study changes in the structural phase state and mechanical properties of bulk-nitrided 08Kh17T steel (0.08 wt % C, 17 wt % Cr, 0.8 wt % Ti, 0.5 wt % Si, 0.8 wt % Mn, 0.025 wt % S, and 0.035 wt % P) upon tempering in the temperature range of 400-700°C. The changes in the mechanical properties of the nitrided steel upon tempering are associated with the predominance of either the solid-solution or precipitation strengthening, i.e., with the presence of martensite in the steel structure at low temperatures of tempering and the precipitation of particles of Cr2N nitrides of different dispersity upon increasing the tempering temperature. The greatest increase in the ultimate tensile strength and yield stress (1.8-2.5 times) at a satisfactory plasticity (no less than 10%) of the bulk-nitrided steel is achieved by tempering bulk-nitrided steel in a temperature range of 600-700°C.

  11. Lithospheric Structure and Active Deformation in the Salton Trough from Coseismic and Postseismic Models of the 2010 Mw 7.2 El Mayor-Cucapah Earthquake

    Science.gov (United States)

    Fielding, E. J.; Huang, M. H.; Dickinson, H.; Freed, A. M.; Burgmann, R.; Gonzalez-Ortega, J. A.; Andronicos, C.

    2016-12-01

    The 4 April 2010 Mw 7.2 El Mayor-Cucapah (EMC) Earthquake ruptured about 120 km along several NW-striking faults to the west of the Cerro Prieto Fault in the Salton Trough of Baja California, Mexico. We analyzed interferometric synthetic aperture radar (SAR), SAR and optical pixel offsets, and continuous and campaign GPS data to optimize an EMC coseismic rupture model with 9 fault segments, which fits the complex structure of the faults. Coseismic slip inversion with a layered elastic model shows that largely right-lateral slip is confined to upper 10 km with strong variations along strike. Near-field GPS measures slip on a north-striking normal fault that ruptured at the beginning of the earthquake, previously inferred from seismic waveforms. EMC Earthquake postseismic deformation shows the Earth's response to the large coseismic stress changes. InSAR shows rapid shallow afterslip at the north and south ends of the main ruptures. Continuous GPS from the Plate Boundary Observatory operated by UNAVCO measures the first six years of postseismic deformation, extremely rapid near the rupture. Afterslip on faults beneath the coseismic rupture cannot explain far-field displacements that are best explained by viscoelastic relaxation of the lower crust and upper mantle. We built a viscoelastic 3D finite element model of the lithosphere and asthenosphere based on available data for the region with the EMC coseismic faults embedded inside. Coseismic slip was imposed on the model, allowed to relax for 5 years, and then compared to the observed surface deformation. Systematic exploration of the viscoelastic parameters shows that horizontal and vertical heterogeneity is required to fit the postseismic deformation. Our preferred viscoelastic model has weaker viscosity layers beneath the Salton Trough than adjacent blocks that are consistent with the inferred differences in the geotherms. Defining mechanical lithosphere as rocks that have viscosities greater than 10^19 Pa s (able

  12. A potential-flow, deformable-body model for fluid-structure interactions with compact vorticity: application to animal swimming measurements

    Science.gov (United States)

    Peng, Jifeng; Dabiri, John O.

    This paper presents an approach to quantify the unsteady fluid forces, moments and mass transport generated by swimming animals, based on measurements of the surrounding flow field. These goals are accomplished within a framework that is independent of the vorticity field, making it unnecessary to directly resolve boundary layers on the animal, body-vortex interactions, or interactions among vortex lines in the wake. Instead, the method identifies Lagrangian coherent structures in the flow, whose dynamics in flows with compact vorticity are shown to be well approximated by potential flow concepts, especially the Kirchhoff and deformation potentials from deformable body theory. Examples of the application of these methods are given for pectoral fin locomotion of the bluegill sunfish and undulatory swimming of jellyfish, and the methods are validated by analysis of a canonical starting vortex ring flow. The transition to a Lagrangian approach toward animal swimming measurements suggests the possibility of implementing recently developed particle tracking (vis-à-vis DPIV) techniques for fully three-dimensional measurements of animal swimming.

  13. A concept for energy harvesting from quasi-static structural deformations through axially loaded bilaterally constrained columns with multiple bifurcation points

    Science.gov (United States)

    Lajnef, N.; Burgueño, R.; Borchani, W.; Sun, Y.

    2014-05-01

    A major obstacle limiting the development of deployable sensing and actuation solutions is the scarcity of power. Converted energy from ambient loading using piezoelectric scavengers is a possible solution. Most of the previously developed research focused on vibration-based piezoelectric harvesters which are typically characterized by a response with a narrow natural frequency range. Several techniques were used to improve their effectiveness. These methods focus only on the transducer’s properties and configurations, but do little to improve the stimuli from the source. In contrast, this work proposes to focus on the input deformations generated within the structure, and the induction of an amplified amplitude and up-converted frequency toward the harvesters’ natural spectrum. This paper introduces the concept of using mechanically-equivalent energy converters and frequency modulators that can transform low-amplitude and low-rate service deformations into an amplified vibration input to the piezoelectric transducer. The introduced concept allows energy conversion within the unexplored quasi-static frequency range (≪1 Hz). The post-buckling behavior of bilaterally constrained columns is used as the mechanism for frequency up-conversion. A bimorph cantilever polyvinylidene fluoride (PVDF) piezoelectric beam is used for energy conversion. Experimental prototypes were built and tested to validate the introduced concept and the levels of extractable power were evaluated for different cases under varying input frequencies. Finally, finite element simulations are reported to provide insight into the scalability and performance of the developed concept.

  14. Heat transport in bulk/nanoporous/bulk silicon devices

    Energy Technology Data Exchange (ETDEWEB)

    Criado-Sancho, M. [Departamento de Ciencias y Técnicas Físicoquimicas, Facultad de Ciencias, UNED, Senda del Rey 9, 20040 Madrid (Spain); Jou, D., E-mail: David.Jou@uab.cat [Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia (Spain); Institut d' Estudis Catalans, Carme 47, 08001 Barcelona, Catalonia (Spain)

    2013-02-04

    We study heat transport in bulk/nanoporous/bulk silicon devices; we show that, despite bulk/nanoporous devices may act as thermal rectifiers, the non-linear aspects of their joint thermal conductance are not strong enough to lead to a negative differential thermal resistance, necessary to allow bulk/nanoporous/bulk Si devices to act as thermal transistors. Furthermore, we explicitly study the effective thermal conductivity of the mentioned devices for several temperatures, geometries, porosities, and pore size.

  15. Extraordinary plasticity of ductile bulk metallic glasses.

    Science.gov (United States)

    Chen, Mingwei; Inoue, Akihisa; Zhang, Wei; Sakurai, Toshio

    2006-06-23

    Shear bands generally initiate strain softening and result in low ductility of metallic glasses. In this Letter, we report high-resolution electron microscope observations of shear bands in a ductile metallic glass. Strain softening caused by localized shearing was found to be effectively prevented by nanocrystallization that is in situ produced by plastic flow within the shear bands, leading to large plasticity and strain hardening. These atomic-scale observations not only well explain the extraordinary plasticity that was recently observed in some bulk metallic glasses, but also reveal a novel deformation mechanism that can effectively improve the ductility of monolithic metallic glasses.

  16. "Understanding" cosmological bulk viscosity

    OpenAIRE

    Zimdahl, Winfried

    1996-01-01

    A universe consisting of two interacting perfect fluids with the same 4-velocity is considered. A heuristic mean free time argument is used to show that the system as a whole cannot be perfect as well but neccessarily implies a nonvanishing bulk viscosity. A new formula for the latter is derived and compared with corresponding results of radiative hydrodynamics.

  17. Bulk chemicals from biomass

    NARCIS (Netherlands)

    Haveren, van J.; Scott, E.L.; Sanders, J.P.M.

    2008-01-01

    Given the current robust forces driving sustainable production, and available biomass conversion technologies, biomass-based routes are expected to make a significant impact on the production of bulk chemicals within 10 years, and a huge impact within 20-30 years. In the Port of Rotterdam there is a

  18. Corrosion behavior of HPT-deformed TiNi alloys in cell culture medium

    Science.gov (United States)

    Shri, D. N. Awang; Tsuchiya, K.; Yamamoto, A.

    2017-09-01

    In recent years there are growing interest in fabrication of bulk nanostructured metals and alloys by using severe plastic deformation (SPD) techniques as new alternative in producing bulk nanocrystalline materials. These techniques allows for processing of bulk, fully dense workpiece with ultrafine grains. Metal undergoes SPD processing in certain techniques such as high pressure torsion (HPT), equal-channel angular pressing (ECAP) or multi-directional forging (MDF) are subjected to extensive hydrostatic pressure that may be used to impart a very high strain to the bulk solid without the introduction of any significant change in overall dimension of the sample. The change in the structure (small grain size and high-volume fraction of grain boundaries) of the material may result in the corrosion behavior different from that of the coarse-grained material. Electrochemical measurements were done to understand the corrosion behavior of TiNi alloys before and after HPT deformation. The experiment was carried out using standard three electrode setup (a sample as working electrode; a platinum wire as a counter electrode and a saturated calomel electrode in saturated KCl as a reference electrode) with the surface area of 26.42 mm2 exposed to the EMEM+10% FBS cell culture medium. The measurements were performed in an incubator with controlled environment at 37 °C and 5% CO2, simulating the cell culture condition. The potential of the specimen was monitored over 1 hour, and the stabilized potential was used as the open-circuit potential (EOCP). Potentiodynamic curves were scanned in the potential range from -0.5 V to 1.5 V relative to the EOCP, at a rate of 0.5 mV/s. The result of OCP-time measurement done in the cell culture medium shows that the OCP of HPT-deformed samples shifts towards to the more positive rather than that of BHPT samples. The OCP of deformed samples were ennobled to more than +70 mV for Ti-50mol%. The shift of OCP towards the nobler direction

  19. Exploiting imperfections in the bulk to direct assembly of surface colloids

    Science.gov (United States)

    Cavallaro, Marcello; Gharbi, Mohamed A.; Beller, Daniel A.; Čopar, Simon; Shi, Zheng; Baumgart, Tobias; Yang, Shu; Kamien, Randall D.; Stebe, Kathleen J.

    2013-01-01

    We exploit the long-ranged elastic fields inherent to confined nematic liquid crystals (LCs) to assemble colloidal particles trapped at the LC interface into reconfigurable structures with complex symmetries and packings. Spherical colloids with homeotropic anchoring trapped at the interface between air and the nematic LC 4-cyano-4′-pentylbiphenyl create quadrupolar distortions in the director field causing particles to repel and consequently form close-packed assemblies with a triangular habit. Here, we report on complex open structures organized via interactions with defects in the bulk. Specifically, by confining the nematic LC in an array of microposts with homeotropic anchoring conditions, we cause defect rings to form at well-defined locations in the bulk of the sample. These defects source elastic deformations that direct the assembly of the interfacially trapped colloids into ring-like assemblies, which recapitulate the defect geometry even when the microposts are completely immersed in the nematic. When the surface density of the colloids is high, they form a ring near the defect and a hexagonal lattice far from it. Because topographically complex substrates are easily fabricated and LC defects are readily reconfigured, this work lays the foundation for a versatile, robust mechanism to direct assembly dynamically over large areas by controlling surface anchoring and associated bulk defect structure. PMID:24191037

  20. The impact of structural deformation in a 2D basin and petroleum system model of the East Coast Basin, New Zealand

    Science.gov (United States)

    Burgreen, B.; Graham, S. A.; Meisling, K. E.

    2013-12-01

    The East Coast Basin of New Zealand is a petroliferous forearc basin that has eluded commercial development largely because of challenges related to its complex structural and tectonic history. Basin formation is associated with three tectonic phases: 1) a Cretaceous convergent margin phase, 2) a Late Cretaceous to Paleogene rifting to passive margin phase, and 3) a Neogene to present convergent margin phase. Beginning in Neogene time, the basin underwent multiple stages of structural deformation including low angle thrust faulting, listric normal faulting, and inversion. This complex basin history provides an ideal situation to test the influence of tectonics on petroleum system development. This study focuses on offshore Hawke Bay where a regional 2D seismic line has been interpreted, palinspastically reconstructed, and incorporated into a basin and petroleum system model. In the model, several paleo-heat flow scenarios are developed to represent the tectonic evolution of the basin. Higher heat flow is modeled during the rifting to passive margin phase, and a reduction in heat flow is modeled during the Neogene phase to account for cold slab subduction. Heat flow scenarios are calibrated to temperature, apatite-fission track data, and vitrinite-intertinite reflectance and fluorescence data from the Hawke Bay-1 and Opoutama-1 wells. The palinspastic reconstructions are integrated into the basin and petroleum system model to assess the impact of different styles of deformation. Faults play a key role in the burial history/rate of burial, fluid migration, and pressure compartmentalization. The relative timing of paleo-heat flow and structural events are tested in the model to understand how they enhance and/or negate effects on petroleum generation. For example, models with early Miocene low angle thrusts (i.e. structural thickening) contemporaneous with remnant high heat flow from the passive margin phase create a scenario for mid-Miocene petroleum generation

  1. Sensing the ups and downs of Las Vegas: InSAR reveals structural control of land subsidence and aquifer-system deformation

    Science.gov (United States)

    Amelung, F.; Galloway, D.L.; Bell, J.W.; Zebker, H.A.; Laczniak, R.J.

    1999-01-01

    Land subsidence in Las Vegas, Nevada, United States, between April 1992 and December 1997 was measured using spaceborne interferometric synthetic aperture radar. The detailed deformation maps clearly show that the spatial extent of subsidence is controlled by geologic structures (faults) and sediment composition (clay thickness). The maximum detected subsidence during the 5.75 yr period is 19 cm. Comparison with leveling data indicates that the subsidence rates declined during the past decade as a result of rising ground-water levels brought about by a net reduction in ground-water extraction. Temporal analysis also detects seasonal subsidence and uplift patterns, which provide information about the elastic and inelastic properties of the aquifer system and their spatial variability.

  2. First-principles investigation of local structure deformation induced by x-ray irradiation in κ -(BEDT-TTF ) 2Cu [N (CN) 2 ] Br

    Science.gov (United States)

    Kang, Lijing; Akagi, Kazuto; Hayashi, Kouichi; Sasaki, Takahiko

    2017-06-01

    We investigated the local structure deformation induced by x-ray irradiation in an organic molecular conductor κ -(BEDT-TTF ) 2Cu [N (CN) 2 ] Br using density-functional-theory (DFT-) based first-principles calculations. Our results demonstrate that the structure change due to x-ray excitation can be predicted by introducing a core hole at specific light atoms of the anion molecules with an infinite lifetime. The formation of a bond-shifted structure triggered by a double excitation was expected as a possible irreversible molecular defect leading to permanent irradiation damage. The calculated change in molecular vibration spectra after irradiation was consistent with the experimental results, and some different vibration modes by further irradiation were also predicted. The calculated local density of states indicates that the bond-shifted structure in the anion layer causes local potential modulation to the carriers (holes) in the cation layer. The introduced potential disorder for the carriers could increase the resistivity due to a localization effect that has been observed experimentally so far.

  3. Effects of tensile strain on the peculiarities of PEO penetration into the nanoporous structure of PET deformed via the crazing mechanism.

    Science.gov (United States)

    Rukhlya, E G; Yarysheva, L M; Volynskii, A L; Bakeev, N F

    2016-04-14

    Solvent crazing involves the development of a highly dispersed fibrillar-porous structure with dimensions of pores and craze fibrils of about 2-20 nm, and crazing by itself can be treated as a universal method for the development of nanoscale porosity. The penetration and release of poly(ethylene oxide) macromolecules into and from the crazes during the development of the nanoporous structure of poly(ethylene terephthalate) have been studied. In particular, PET has been deformed in dilute or semidilute (unentangled as well as entangled) solutions of PEO (a Mw of 4 and 40 kDa) via the mechanism of solvent crazing. Hydrodynamic coil radii Rh, blob sizes ξ, and concentration ranges (crossover and entanglement concentrations) have been determined for the PEO solutions. The evolution of the craze structure (change in porosity W and pore diameters d) has been described as a function of the tensile strain of PET during its drawing in an adsorption-active medium and in the PEO solutions. PEO has been shown to penetrate into the nanoporous structure of the crazes under the conditions corresponding to Rh≤d and ξ PEO adsorption at the highly developed surface of PET, and the mechanism of PEO transport in the nanopores are equally important factors affecting the direction of the macromolecule mass transfer in the nanopores (penetration or release) and PEO content variation as a function of PET tensile strain.

  4. On the role of API in determining porosity, pore structure and bulk modulus of the skeletal material in pharmaceutical tablets formed with MCC as sole excipient.

    Science.gov (United States)

    Ridgway, Cathy; Bawuah, Prince; Markl, Daniel; Zeitler, J Axel; Ketolainen, Jarkko; Peiponen, Kai-Erik; Gane, Patrick

    2017-06-30

    The physical properties and mechanical integrity of pharmaceutical tablets are of major importance when loading with active pharmaceutical ingredient(s) (API) in order to ensure ease of processing, control of dosage and stability during transportation and handling prior to patient consumption. The interaction between API and excipient, acting as functional extender and binder, however, is little understood in this context. The API indomethacin is combined in this study with microcrystalline cellulose (MCC) at increasing loading levels. Tablets from the defined API/MCC ratios are made under conditions of controlled porosity and tablet thickness, resulting from different compression conditions, and thus compaction levels. Mercury intrusion porosimetry is used to establish the accessible pore volume, pore size distribution and, adopting the observed region of elastic intrusion-extrusion at high pressure, an elastic bulk modulus of the skeletal material is recorded. Porosity values are compared to previously published values derived from terahertz (THz) refractive index data obtained from exactly the same tablet sample sets. It is shown that the elastic bulk modulus is dependent on API wt% loading under constant tablet preparation conditions delivering equal dimensions and porosity. The findings are considered of novel value in respect to establishing consistency of tablet production and optimisation of physical properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. 14 CFR 27.305 - Strength and deformation.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Strength and deformation. 27.305 Section 27... deformation. (a) The structure must be able to support limit loads without detrimental or permanent deformation. At any load up to limit loads, the deformation may not interfere with safe operation. (b) The...

  6. 14 CFR 29.305 - Strength and deformation.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Strength and deformation. 29.305 Section 29... deformation. (a) The structure must be able to support limit loads without detrimental or permanent deformation. At any load up to limit loads, the deformation may not interfere with safe operation. (b) The...

  7. 14 CFR 23.305 - Strength and deformation.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Strength and deformation. 23.305 Section 23... Strength and deformation. (a) The structure must be able to support limit loads without detrimental, permanent deformation. At any load up to limit loads, the deformation may not interfere with safe operation...

  8. Perceptual transparency from image deformation

    Science.gov (United States)

    Kawabe, Takahiro; Maruya, Kazushi; Nishida, Shin’ya

    2015-01-01

    Human vision has a remarkable ability to perceive two layers at the same retinal locations, a transparent layer in front of a background surface. Critical image cues to perceptual transparency, studied extensively in the past, are changes in luminance or color that could be caused by light absorptions and reflections by the front layer, but such image changes may not be clearly visible when the front layer consists of a pure transparent material such as water. Our daily experiences with transparent materials of this kind suggest that an alternative potential cue of visual transparency is image deformations of a background pattern caused by light refraction. Although previous studies have indicated that these image deformations, at least static ones, play little role in perceptual transparency, here we show that dynamic image deformations of the background pattern, which could be produced by light refraction on a moving liquid’s surface, can produce a vivid impression of a transparent liquid layer without the aid of any other visual cues as to the presence of a transparent layer. Furthermore, a transparent liquid layer perceptually emerges even from a randomly generated dynamic image deformation as long as it is similar to real liquid deformations in its spatiotemporal frequency profile. Our findings indicate that the brain can perceptually infer the presence of “invisible” transparent liquids by analyzing the spatiotemporal structure of dynamic image deformation, for which it uses a relatively simple computation that does not require high-level knowledge about the detailed physics of liquid deformation. PMID:26240313

  9. MD Simulations of Papillomavirus DNA-E2 Protein Complexes Hints at a Protein Structural Code for DNA Deformation

    OpenAIRE

    Falconi, M.; Oteri, F.; Eliseo, T.; Cicero, D. O.; Desideri, A.

    2008-01-01

    The structural dynamics of the DNA binding domains of the human papillomavirus strain 16 and the bovine papillomavirus strain 1, complexed with their DNA targets, has been investigated by modeling, molecular dynamics simulations, and nuclear magnetic resonance analysis. The simulations underline different dynamical features of the protein scaffolds and a different mechanical interaction of the two proteins with DNA. The two protein structures, although very similar, show differences in the re...

  10. Diffusion or bulk flow

    DEFF Research Database (Denmark)

    Schulz, Alexander

    2015-01-01

    symplasmic pathway from mesophyll to sieve elements. Crucial for the driving force is the question where water enters the pre-phloem pathway. Surprisingly, the role of PD in water movement has not been addressed so far appropriately. Modeling of assimilate and water fluxes indicates that in symplasmic...... the concentration gradient or bulk flow along a pressure gradient. The driving force seems to depend on the mode of phloem loading. In a majority of plant species phloem loading is a thermodynamically active process, involving the activity of membrane transporters in the sieve-element companion cell complex. Since...... is currently matter of discussion, called passive symplasmic loading. Based on the limited material available, this review compares the different loading modes and suggests that diffusion is the driving force in apoplasmic loaders, while bulk flow plays an increasing role in plants having a continuous...

  11. Diffusion or bulk flow

    DEFF Research Database (Denmark)

    Schulz, Alexander

    2015-01-01

    is currently matter of discussion, called passive symplasmic loading. Based on the limited material available, this review compares the different loading modes and suggests that diffusion is the driving force in apoplasmic loaders, while bulk flow plays an increasing role in plants having a continuous...... the concentration gradient or bulk flow along a pressure gradient. The driving force seems to depend on the mode of phloem loading. In a majority of plant species phloem loading is a thermodynamically active process, involving the activity of membrane transporters in the sieve-element companion cell complex. Since...... assimilate movement includes an apoplasmic step, this mode is called apoplasmic loading. Well established is also the polymer-trap loading mode, where the phloem-transport sugars are raffinose-family oligomers in herbaceous plants. Also this mode depends on the investment of energy, here for sugar...

  12. Micromegas in a bulk

    CERN Document Server

    Giomataris, Ioanis; Andriamonje, Samuel A; Aune, S; Charpak, Georges; Colas, P; Giganon, Arnaud; Rebourgeard, P C; Salin, P; Rebourgeard, Ph.

    2006-01-01

    In this paper we present a novel way to manufacture the bulk Micromegas detector. A simple process based on the PCB (Printed Circuit Board) technology is employed to produce the entire sensitive detector. Such fabrication process could be extended to very large area detectors made by the industry. The low cost fabrication together with the robustness of the electrode materials will make it extremely attractive for several applications ranging from particle physics and astrophysics to medicine

  13. Micromegas in a bulk

    Energy Technology Data Exchange (ETDEWEB)

    Giomataris, I. [DAPNIA, CEA Saclay, F91191 Gif sur Yvette CEDEX (France)]. E-mail: ioa@hep.saclay.cea.fr; De Oliveira, R. [CERN, Geneva (Switzerland); Andriamonje, S. [DAPNIA, CEA Saclay, F91191 Gif sur Yvette CEDEX (France); Aune, S. [DAPNIA, CEA Saclay, F91191 Gif sur Yvette CEDEX (France); Charpak, G. [CERN, Geneva (Switzerland); Colas, P. [DAPNIA, CEA Saclay, F91191 Gif sur Yvette CEDEX (France); Fanourakis, G. [Institute of Nuclear Physcis, NCSR Demokritos, Aghia Paraskevi 15310 (Greece); Ferrer, E. [DAPNIA, CEA Saclay, F91191 Gif sur Yvette CEDEX (France); Giganon, A. [DAPNIA, CEA Saclay, F91191 Gif sur Yvette CEDEX (France); Rebourgeard, Ph. [DAPNIA, CEA Saclay, F91191 Gif sur Yvette CEDEX (France); Salin, P. [DAPNIA, CEA Saclay, F91191 Gif sur Yvette CEDEX (France)

    2006-05-10

    In this paper, we present a novel way to manufacture the bulk Micromegas detector. A simple process based on the Printed Circuit Board (PCB) technology is employed to produce the entire sensitive detector. Such a fabrication process could be extended to very large area detectors made by the industry. The low cost fabrication together with the robus