Science.gov

Sample records for highly deformed states

  1. Anisotropy and oxidative resistance of highly crosslinked UHMWPE after deformation processing by solid-state ram extrusion.

    PubMed

    Kurtz, Steven M; Mazzucco, Dan; Rimnac, Clare M; Schroeder, Dave

    2006-01-01

    Solid-state deformation processing is a promising technique for modifying the physical and mechanical properties of highly crosslinked ultra-high molecular weight polyethylene (UHMWPE) beyond simple thermal treatment cycles that have been employed previously. This study evaluates anisotropy and oxidative resistance in a novel, radiation crosslinked (50 kGy) UHMWPE material (ArComXL: Biomet, Inc., Warsaw, IN), incorporating solid-state, deformation processing by extrusion below the melt transition for application in total hip arthroplasty. Tensile, compression, and small punch tests were conducted to evaluate the material properties in the three principal axes of the resulting material. Furthermore, short-term oxidative resistance was evaluated using Fourier transform infrared spectroscopy and the small punch test in conjunction with accelerated shelf aging protocols. The results of this testing indicate that the material is anisotropic, with significantly enhanced strength oriented along the long axis of the rod. For certain other properties, the magnitude of the anisotropy was relatively slight, especially in the elastic regime, in which only a 20% difference was noted between the long axis of the rod and the orthogonal, radial direction. The highly crosslinked material contains detectable free radicals, at a concentration that is 90% less than control, gamma inert sterilized UHMWPE. An unexpected finding of this study was evidence of oxidative stability of the deformation-processed material, even after 4 weeks of accelerated aging in a pressure vessel containing five atmospheres of oxygen (ASTM F2003), which resulted in macroscopic embrittlement of the control material. The oxidative stability observed in ArComXL suggests that the deformation-processed material may be suitable for air-permeable packaging and gas sterilization, which has thus far been reserved for remelted highly crosslinked UHMWPE.

  2. High Temperature Solid-State Coeval Brittle and Ductile Deformation during Cooling of Lake Edison Granodiorite (Sierra Nevada, California)

    NASA Astrophysics Data System (ADS)

    Pennacchioni, G.

    2009-12-01

    In the Lake Edison (LE) granodiorite (88Ma) of the Bear Creek area (Cretaceous Mono Pass intrusive suite, Sierra Nevada, CA) different sets of fractures developed during the high temperature stages of post-magmatic cooling. These fractures strongly localized successive ductile and later brittle shear deformation, but many pristine fractures do not show any shear offset (i.e. are joints). Away from the contact with the younger (86Ma) Mono Creek granite, the LE granodiorite mainly show a single dominant set of steeply dipping fractures striking around E-W to ENE-WSW which were exploited as left-handed strike-slip ductile shear zones and later as faults with identical kinematics. In the proximity of the contact, a second (dominant) set of steeply dipping fractures is present, striking about NNE-SSW, with a right-handed ductile shear reactivation and forming a conjugate array with the E-W set; many leucocratic dykes (including pegmatite) also localized the shear deformation within the granodiorite. Left-handed shear zones commonly overprint the right-handed ones, but the opposite is also observed which suggests that the two sets developed at the same time. Ductile shear zones are associated with a background solid state foliation in the host granodiorite which is mainly developed towards the contact and which has been referred to the Rosy Finch Shear Zone in the area. The mineral fabric along the foliation and along both the left- and right-handed localized shear zones indicate deformation T>500°C. The overall structural association is consistent with a regional shortening direction oriented about NW-SE. Fractures, including joints (occurring with the same orientation of the conjugate shear fractures), which form the precursory structures of shear zones, developed at the same time of ductile deformation and locally overprint the shear zones. The geometry and spatial arrangement of these precursory fractures control the patterns of ductile deformation of the host rocks

  3. Paleotectonic control on distribution of long-term deformation in the Central United States from high-resolution seismic data

    NASA Astrophysics Data System (ADS)

    Magnani, M.; McIntosh, K. D.; Guo, L.

    2011-12-01

    The theory of plate tectonics has provided earth science with a framework to explain why the majority of earthquakes occur at plate boundaries. By contrast, the processes leading to intraplate earthquakes are still poorly understood worldwide because a) the very occurrence of such earthquakes violate plate tectonic theory; b) these earthquakes have long recurrence intervals due to intrinsic low strain rates imposed by far field plate boundary forces, and c) they occur in relatively tectonically quiescent areas where major intracontinental structures are buried/unexposed, and therefore poorly understood. While we know that intraplate earthquakes result from plate-driving forces transmitted through plate interiors, we still do not understand what controls the spatial and temporal pattern of these events. One of the most studied intracontinental seismic zones in the world is the central United States, home to the New Madrid seismic zone, where repeated large magnitude earthquakes have shaken the ground for the past few thousands years, but little deformation is measured at the surface and observed in the subsurface. In the past few years several lines of evidence have emerged showing that currently aseismic portions of the central United States have been the location of large magnitude earthquakes in the recent past (Holocene). Here we summarize the main results of the Moonwalk Project, a ~950 km-long high-resolution marine seismic reflection and CHIRP profile acquired on the Mississippi River from Cape Girardeau, Missouri, to Lake Providence, Louisiana. The profile images the New Madrid fault system as well as several additional faults outside the active fault zone (e.g. the Meeman-Shelby Fault - see Hao et al., this session), where the deformed river alluvium constrains the youngest age of deformation to the Holocene. The data also illuminate liquefaction-induced structures at few locations, one of them located at the Arkansas/Louisiana border, ~360 km south of the

  4. State-variable theories for nonelastic deformation

    SciTech Connect

    Li, C.Y.

    1981-01-01

    The various concepts of mechanical equation of state for nonelastic deformation in crystalline solids, originally proposed for plastic deformation, have been recently extended to describe additional phenomena such as anelastic and microplastic deformation including the Bauschinger effect. It has been demonstrated that it is possible to predict, based on current state variables in a unified way, the mechanical response of a material under an arbitrary loading. Thus, if the evolution laws of the state variables are known, one can describe the behavior of a material for a thermal-mechanical path of interest, for example, during constant load (or stress) creep without relying on specialized theories. Some of the existing theories of mechanical equation of state for nonelastic deformation are reviewed. The establishment of useful forms of mechanical equation of state has to depend on extensive experimentation in the same way as that involved in the development, for example, the ideal gas law. Recent experimental efforts are also reviewed. It has been possible to develop state-variable deformation models based on experimental findings and apply them to creep, cyclic deformation, and other time-dependent deformation. Attempts are being made to correlate the material parameters of the state-variable models with the microstructure of a material. 24 figures.

  5. Deformation of partially pumped active mirrors for high average-power diode-pumped solid-state lasers.

    PubMed

    Albach, Daniel; LeTouzé, Geoffroy; Chanteloup, Jean-Christophe

    2011-04-25

    We discuss the deformation of a partially pumped active mirror amplifier as a free standing disk, as implemented in several laser systems. We rely on the Lucia laser project to experimentally evaluate the analytical and numerical deformation models.

  6. Highly deformable nanofilaments in flow

    NASA Astrophysics Data System (ADS)

    Pawłowska, S.

    2016-10-01

    Experimental analysis of hydrogel nanofilaments conveyed by flow is conducted to help in understanding physical phenomena responsible for transport properties and shape deformations of long bio-objects, like DNA or proteins. Investigated hydrogel nanofilaments exhibit typical macromolecules-like behavior, as spontaneous conformational changes and cross-flow migration. Results of the experiments indicate critical role of thermal fluctuations behavior of single filaments.

  7. Highly deformable bones: unusual deformation mechanisms of seahorse armor.

    PubMed

    Porter, Michael M; Novitskaya, Ekaterina; Castro-Ceseña, Ana Bertha; Meyers, Marc A; McKittrick, Joanna

    2013-06-01

    Multifunctional materials and devices found in nature serve as inspiration for advanced synthetic materials, structures and robotics. Here, we elucidate the architecture and unusual deformation mechanisms of seahorse tails that provide prehension as well as protection against predators. The seahorse tail is composed of subdermal bony plates arranged in articulating ring-like segments that overlap for controlled ventral bending and twisting. The bony plates are highly deformable materials designed to slide past one another and buckle when compressed. This complex plate and segment motion, along with the unique hardness distribution and structural hierarchy of each plate, provide seahorses with joint flexibility while shielding them against impact and crushing. Mimicking seahorse armor may lead to novel bio-inspired technologies, such as flexible armor, fracture-resistant structures or prehensile robotics.

  8. Liquid Droplets on a Highly Deformable Membrane

    NASA Astrophysics Data System (ADS)

    Schulman, Rafael; Dalnoki-Veress, Kari

    2015-11-01

    We present measurements of the deformation produced by micro-droplets atop thin elastomeric and glassy free-standing films. Due to the Laplace pressure, the droplets deform the elastic membrane thereby forming a bulge. Thus, there are two angles that define the droplet/membrane geometry: the angle the liquid surface makes with the film and the angle the deformed bulge makes with the film. The contact line geometry is well captured by a Neumann construction which includes contributions from interfacial and mechanical tensions. Finally, we show that a droplet atop a film with biaxial tension assumes an equilibrium shape which is elongated along the axis of high tension.

  9. Nuclear ground-state masses and deformations: FRDM(2012)

    SciTech Connect

    Moller, P.; Sierk, A. J.; Ichikawa, T.; Sagawa, H.

    2016-03-25

    Here, we tabulate the atomic mass excesses and binding energies, ground-state shell-plus-pairing corrections, ground-state microscopic corrections, and nuclear ground-state deformations of 9318 nuclei ranging from 16O to A=339. The calculations are based on the finite-range droplet macroscopic and the folded-Yukawa single-particle microscopic nuclear-structure models, which are completely specified. Relative to our FRDM(1992) mass table in Möller et al. (1995), the results are obtained in the same model, but with considerably improved treatment of deformation and fewer of the approximations that were necessary earlier, due to limitations in computer power. The more accurate execution of the model and the more extensive and more accurate experimental mass data base now available allow us to determine one additional macroscopic-model parameter, the density-symmetry coefficient LL, which was not varied in the previous calculation, but set to zero. Because we now realize that the FRDM is inaccurate for some highly deformed shapes occurring in fission, because some effects are derived in terms of perturbations around a sphere, we only adjust its macroscopic parameters to ground-state masses.

  10. Nuclear ground-state masses and deformations: FRDM(2012)

    DOE PAGES

    Moller, P.; Sierk, A. J.; Ichikawa, T.; ...

    2016-03-25

    Here, we tabulate the atomic mass excesses and binding energies, ground-state shell-plus-pairing corrections, ground-state microscopic corrections, and nuclear ground-state deformations of 9318 nuclei ranging from 16O to A=339. The calculations are based on the finite-range droplet macroscopic and the folded-Yukawa single-particle microscopic nuclear-structure models, which are completely specified. Relative to our FRDM(1992) mass table in Möller et al. (1995), the results are obtained in the same model, but with considerably improved treatment of deformation and fewer of the approximations that were necessary earlier, due to limitations in computer power. The more accurate execution of the model and the more extensivemore » and more accurate experimental mass data base now available allow us to determine one additional macroscopic-model parameter, the density-symmetry coefficient LL, which was not varied in the previous calculation, but set to zero. Because we now realize that the FRDM is inaccurate for some highly deformed shapes occurring in fission, because some effects are derived in terms of perturbations around a sphere, we only adjust its macroscopic parameters to ground-state masses.« less

  11. Nuclear ground-state masses and deformations: FRDM(2012)

    NASA Astrophysics Data System (ADS)

    Möller, P.; Sierk, A. J.; Ichikawa, T.; Sagawa, H.

    2016-05-01

    We tabulate the atomic mass excesses and binding energies, ground-state shell-plus-pairing corrections, ground-state microscopic corrections, and nuclear ground-state deformations of 9318 nuclei ranging from 16O to A = 339. The calculations are based on the finite-range droplet macroscopic and the folded-Yukawa single-particle microscopic nuclear-structure models, which are completely specified. Relative to our FRDM(1992) mass table in Möller et al. (1995), the results are obtained in the same model, but with considerably improved treatment of deformation and fewer of the approximations that were necessary earlier, due to limitations in computer power. The more accurate execution of the model and the more extensive and more accurate experimental mass data base now available allow us to determine one additional macroscopic-model parameter, the density-symmetry coefficient L, which was not varied in the previous calculation, but set to zero. Because we now realize that the FRDM is inaccurate for some highly deformed shapes occurring in fission, because some effects are derived in terms of perturbations around a sphere, we only adjust its macroscopic parameters to ground-state masses.

  12. Acoustic emission of coal in the postlimiting deformation state

    SciTech Connect

    Voznesenskii, A.S.; Tavostin, M.N.

    2005-08-01

    The features of acoustic emission in coal samples in the state of pre- and postlimiting deformation are considered. It is shown that in the postlimiting deformation stages and in the transient period, a contrary change is observed in a correlation coefficient of the acoustic emission activity N{Sigma} recorded in the upper and lower portions of a sample; whereas in the prelimiting deformation stages, this change is consistent. It is proposed to recognize the stages of deformation by the correlation coefficient of N{Sigma} recorded in different zones: a positive coefficient corresponds to the prelimiting stage of deformation, and a negative one corresponds to the postlimiting stage.

  13. Grain boundary engineering of highly deformable ceramics

    SciTech Connect

    Mecartney, M.L.

    2000-07-01

    Highly deformable ceramics can be created with the addition of intergranular silicate phases. These amorphous intergranular phases can assist in superplastic deformation by relieving stress concentrations and minimizing grain growth if the appropriate intergranular compositions are selected. Examples from 3Y-TZP and 8Y-CSZ ceramics are discussed. The grain boundary chemistry is analyzed by high resolution analytical TEM is found to have a strong influence on the cohesion of the grains both at high temperature and at room temperature. Intergranular phases with a high ionic character and containing large ions with a relatively weak bond strength appear to cause premature failure. In contrast, intergranular phases with a high degree of covalent character and similar or smaller ions than the ceramic and a high ionic bond strength are the best for grain boundary adhesion and prevention of both cavitation at high temperatures and intergranular fracture at room temperature.

  14. q -deformed noncommutative cat states and their nonclassical properties

    NASA Astrophysics Data System (ADS)

    Dey, Sanjib

    2015-02-01

    We study several classical-like properties of q -deformed nonlinear coherent states as well as nonclassical behaviors of q -deformed version of the Schrödinger cat states in noncommutative space. Coherent states in q -deformed space are found to be minimum uncertainty states together with the squeezed photon distributions unlike the ordinary systems, where the photon distributions are always Poissonian. Several advantages of utilizing cat states in noncommutative space over the standard quantum mechanical spaces have been reported here. For instance, the q -deformed parameter has been utilized to improve the squeezing of the quadrature beyond the ordinary case. Most importantly, the parameter provides an extra degree of freedom by which we achieve both quadrature squeezed and number squeezed cat states at the same time in a single system, which is impossible to achieve from ordinary cat states.

  15. High strain rate deformation of layered nanocomposites.

    PubMed

    Lee, Jae-Hwang; Veysset, David; Singer, Jonathan P; Retsch, Markus; Saini, Gagan; Pezeril, Thomas; Nelson, Keith A; Thomas, Edwin L

    2012-01-01

    Insight into the mechanical behaviour of nanomaterials under the extreme condition of very high deformation rates and to very large strains is needed to provide improved understanding for the development of new protective materials. Applications include protection against bullets for body armour, micrometeorites for satellites, and high-speed particle impact for jet engine turbine blades. Here we use a microscopic ballistic test to report the responses of periodic glassy-rubbery layered block-copolymer nanostructures to impact from hypervelocity micron-sized silica spheres. Entire deformation fields are experimentally visualized at an exceptionally high resolution (below 10 nm) and we discover how the microstructure dissipates the impact energy via layer kinking, layer compression, extreme chain conformational flattening, domain fragmentation and segmental mixing to form a liquid phase. Orientation-dependent experiments show that the dissipation can be enhanced by 30% by proper orientation of the layers.

  16. Block versus continuum deformation in the Western United States

    USGS Publications Warehouse

    King, G.; Oppenheimer, D.; Amelung, F.

    1994-01-01

    The relative role of block versus continuum deformation of continental lithosphere is a current subject of debate. Continuous deformation is suggested by distributed seismicity at continental plate margins and by cumulative seismic moment sums which yield slip estimates that are less than estimates from plate motion studies. In contrast, block models are favored by geologic studies of displacement in places like Asia. A problem in this debate is a lack of data from which unequivocal conclusions may be reached. In this paper we apply the techniques of study used in regions such as the Alpine-Himalayan belt to an area with a wealth of instrumental data-the Western United States. By comparing plate rates to seismic moment release rates and assuming a typical seismogenic layer thickness of 15 km it appears that since 1850 about 60% of the Pacific-North America motion across the plate boundary in California and Nevada has occurred seismically and 40% aseismically. The San Francisco Bay area shows similar partitioning between seismic and aseismic deformation, and it can be shown that within the seismogenic depth range aseismic deformation is concentrated near the surface and at depth. In some cases this deformation can be located on creeping surface faults, but elsewhere it is spread over a several kilometer wide zone adjacent to the fault. These superficial creeping deformation zones may be responsible for the palaeomagnetic rotations that have been ascribed elsewhere to the surface expression of continuum deformation in the lithosphere. Our results support the dominant role of non-continuum deformation processes with the implication that deformation localization by strain softening must occur in the lower crust and probably the upper mantle. Our conclusions apply only to the regions where the data are good, and even within the Western United States (i.e., the Basin and Range) deformation styles remain poorly resolved. Nonetheless, we maintain that block motion is the

  17. High-Temperature Deformation of Enstatite Aggregates

    NASA Astrophysics Data System (ADS)

    Bystricky, M.; Lawlis, J.; Mackwell, S. J.; Heidelbach, F.; Raterron, P. C.

    2011-12-01

    Although enstatite is a significant component of the upper mantle, its rheology is still poorly understood. We have performed an experimental investigation of the mechanical properties of enstatite at high pressure and temperature in the proto- and ortho-enstatite stability fields. Synthetic enstatite powders were produced by reacting San Carlos olivine powders with lab-grade quartz. Powders were hot-pressed at high PT, and were then baked at 1000°C under controlled oxygen fugacity conditions to remove all hydrous defect species. The polycrystalline enstatite samples were deformed in a Paterson gas-medium apparatus at temperatures of 1200-1300°C, an oxygen fugacity buffered at Ni/NiO, and confining pressures of 300 or 450 MPa. Under these conditions, samples were in the orthoenstatite field at 450 MPa and likely mainly in the protoenstatite field at 300 MPa. At both confining pressures, the mechanical data display a progressive increase of the stress exponent n from 1 to 3 as a function of differential stress, suggesting a transition from diffusional to dislocation creep. Non-linear least-square fits to the high-stress data yielded flow laws with n=3 and activation energies of 600 and 720 kJ/mol for ortho- and proto-enstatite, respectively. The measured strengths are significantly higher than those derived from Raleigh et al. (1971) and Ross and Nielsen (1978), due to the influence of water on the mechanical behavior of their samples. Deformed samples were analysed using optical microscopy, SEM and TEM. Because enstatite reverts to clinoenstatite during quenching, the microstructures present highly twinned grains composed of thin alternating domains of clino- and ortho-pyroxene. Nevertheless, the microstructures show evidence of dislocation processes in the form of undulatory extinction and kink bands. Crystallographic preferred orientations measured by EBSD are axisymmetric and indicate preferential slip on (100)[001]. High resolution TEM indicates that for

  18. Machining and grinding: High rate deformation in practice

    SciTech Connect

    Follansbee, P.S.

    1993-04-01

    Machining and grinding are well-established material-working operations involving highly non-uniform deformation and failure processes. A typical machining operation is characterized by uncertain boundary conditions (e.g.,surface interactions), three-dimensional stress states, large strains, high strain rates, non-uniform temperatures, highly localized deformations, and failure by both nominally ductile and brittle mechanisms. While machining and grinding are thought to be dominated by empiricism, even a cursory inspection leads one to the conclusion that this results more from necessity arising out of the complicated and highly interdisciplinary nature of the processes than from the lack thereof. With these conditions in mind, the purpose of this paper is to outline the current understanding of strain rate effects in metals.

  19. Machining and grinding: High rate deformation in practice

    SciTech Connect

    Follansbee, P.S.

    1993-01-01

    Machining and grinding are well-established material-working operations involving highly non-uniform deformation and failure processes. A typical machining operation is characterized by uncertain boundary conditions (e.g.,surface interactions), three-dimensional stress states, large strains, high strain rates, non-uniform temperatures, highly localized deformations, and failure by both nominally ductile and brittle mechanisms. While machining and grinding are thought to be dominated by empiricism, even a cursory inspection leads one to the conclusion that this results more from necessity arising out of the complicated and highly interdisciplinary nature of the processes than from the lack thereof. With these conditions in mind, the purpose of this paper is to outline the current understanding of strain rate effects in metals.

  20. Insect wing deformation measurements using high speed digital holographic interferometry.

    PubMed

    Aguayo, Daniel D; Mendoza Santoyo, Fernando; De la Torre-I, Manuel H; Salas-Araiza, Manuel D; Caloca-Mendez, Cristian; Gutierrez Hernandez, David Asael

    2010-03-15

    An out-of-plane digital holographic interferometry system is used to detect and measure insect's wing micro deformations. The in-vivo phenomenon of the flapping is registered using a high power cw laser and a high speed camera. A series of digital holograms with the deformation encoded are obtained. Full field deformation maps are presented for an eastern tiger swallowtail butterfly (Pterourus multicaudata). Results show no uniform or symmetrical deformations between wings. These deformations are in the order of hundreds of nanometers over the entire surface. Out-of-plane deformation maps are presented using the unwrapped phase maps.

  1. High stroke pixel for a deformable mirror

    DOEpatents

    Miles, Robin R.; Papavasiliou, Alexandros P.

    2005-09-20

    A mirror pixel that can be fabricated using standard MEMS methods for a deformable mirror. The pixel is electrostatically actuated and is capable of the high deflections needed for spaced-based mirror applications. In one embodiment, the mirror comprises three layers, a top or mirror layer, a middle layer which consists of flexures, and a comb drive layer, with the flexures of the middle layer attached to the mirror layer and to the comb drive layer. The comb drives are attached to a frame via spring flexures. A number of these mirror pixels can be used to construct a large mirror assembly. The actuator for the mirror pixel may be configured as a crenellated beam with one end fixedly secured, or configured as a scissor jack. The mirror pixels may be used in various applications requiring high stroke adaptive optics.

  2. Dynamic shear deformation in high purity Fe

    SciTech Connect

    Cerreta, Ellen K; Bingert, John F; Trujillo, Carl P; Lopez, Mike F; Gray, George T

    2009-01-01

    The forced shear test specimen, first developed by Meyer et al. [Meyer L. et al., Critical Adiabatic Shear Strength of Low Alloyed Steel Under Compressive Loading, Metallurgical Applications of Shock Wave and High Strain Rate Phenomena (Marcel Decker, 1986), 657; Hartmann K. et al., Metallurgical Effects on Impact Loaded Materials, Shock Waves and High Strain rate Phenomena in Metals (Plenum, 1981), 325-337.], has been utilized in a number of studies. While the geometry of this specimen does not allow for the microstructure to exactly define the location of shear band formation and the overall mechanical response of a specimen is highly sensitive to the geometry utilized, the forced shear specimen is useful for characterizing the influence of parameters such as strain rate, temperature, strain, and load on the microstructural evolution within a shear band. Additionally, many studies have utilized this geometry to advance the understanding of shear band development. In this study, by varying the geometry, specifically the ratio of the inner hole to the outer hat diameter, the dynamic shear localization response of high purity Fe was examined. Post mortem characterization was performed to quantify the width of the localizations and examine the microstructural and textural evolution of shear deformation in a bcc metal. Increased instability in mechanical response is strongly linked with development of enhanced intergranular misorientations, high angle boundaries, and classical shear textures characterized through orientation distribution functions.

  3. Elastoplastic behavior of copper upon high-strain-rate deformation

    NASA Astrophysics Data System (ADS)

    Chembarisova, R. G.

    2015-06-01

    The deformation behavior of copper under conditions of high-strain-rate deformation has been investigated based on the model of elastoplastic medium with allowance for the kinetics of plastic deformation. Data have been obtained on the evolution of the dislocation subsystem, namely, on the average dislocation density, density of mobile dislocations, velocity of dislocation slip, concentration of deformation-induced vacancies, and density of twins. The coefficient of the annihilation of screw dislocations has been estimated depending on pressure and temperature. It has been shown that severe shear stresses that arise upon high-strain-rate deformation can lead to a significant increase in the concentration of vacancies. The time of the dislocation annihilation upon their nonconservative motion has been estimated. It has been shown that this time is much greater than the time of the deformation process in the samples, which makes it possible to exclude the annihilation of dislocations upon their nonconservative motion from the active mechanisms of deformation.

  4. The use of ion beam cleaning to obtain high quality cold welds with minimal deformation

    NASA Technical Reports Server (NTRS)

    Sater, B. L.; Moore, T. J.

    1978-01-01

    A variation of cold welding is described which utilizes an ion beam to clean mating surfaces prior to joining in a vacuum environment. High quality solid state welds were produced with minimal deformation.

  5. Biaxial deformation in high purity aluminum

    DOE PAGES

    Livescu, V.; Bingert, J. F.; Liu, C.; ...

    2015-09-25

    The convergence of multiple characterization tools has been applied to investigate the relationship of microstructure on damage evolution in high purity aluminum. The extremely coarse grain size of the disc-shaped sample provided a quasi-two dimensional structure from which the location of surface-measured features could be inferred. In particular, the role of pre-existing defects on damage growth was accessible due to the presence of casting porosity in the aluminum. Micro tomography, electron backscatter diffraction, and digital image correlation were applied to interrogate the sample in three dimensions. Recently micro-bulge testing apparatus was used to deform the pre-characterized disc of aluminum inmore » biaxial tension, and related analysis techniques were applied to map local strain fields. Subsequent post-mortem characterization of the failed sample was performed to correlate structure to damaged regions. We determined that strain localization and associated damage was most strongly correlated with grain boundary intersections and plastic anisotropy gradients between grains. Pre-existing voids played less of an apparent role than was perhaps initially expected. Finally, these combined techniques provide insight to the mechanism of damage initiation, propagation, and failure, along with a test bed for predictive damage models incorporating anisotropic microstructural effects.« less

  6. Biaxial deformation in high purity aluminum

    SciTech Connect

    Livescu, V.; Bingert, J. F.; Liu, C.; Lovato, M. L.; Patterson, B. M.

    2015-09-25

    The convergence of multiple characterization tools has been applied to investigate the relationship of microstructure on damage evolution in high purity aluminum. The extremely coarse grain size of the disc-shaped sample provided a quasi-two dimensional structure from which the location of surface-measured features could be inferred. In particular, the role of pre-existing defects on damage growth was accessible due to the presence of casting porosity in the aluminum. Micro tomography, electron backscatter diffraction, and digital image correlation were applied to interrogate the sample in three dimensions. Recently micro-bulge testing apparatus was used to deform the pre-characterized disc of aluminum in biaxial tension, and related analysis techniques were applied to map local strain fields. Subsequent post-mortem characterization of the failed sample was performed to correlate structure to damaged regions. We determined that strain localization and associated damage was most strongly correlated with grain boundary intersections and plastic anisotropy gradients between grains. Pre-existing voids played less of an apparent role than was perhaps initially expected. Finally, these combined techniques provide insight to the mechanism of damage initiation, propagation, and failure, along with a test bed for predictive damage models incorporating anisotropic microstructural effects.

  7. Use of solid-state nanopores for sensing co-translocational deformation of nano-liposomes.

    PubMed

    Goyal, Gaurav; Darvish, Armin; Kim, Min Jun

    2015-07-21

    Membrane deformation of nano-vesicles is crucial in many cellular processes such as virus entry into the host cell, membrane fusion, and endo- and exocytosis; however, studying the deformation of sub-100 nm soft vesicles is very challenging using the conventional techniques. In this paper, we report detecting co-translocational deformation of individual 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) nano-liposomes using solid-state nanopores. Electrokinetic translocation through the nanopore caused the soft DOPC liposomes (85 nm diameter) to change their shape, which we attribute to the strong electric field strength and physical confinement inside the pore. The experiments were performed at varying transmembrane voltages and the deformation was observed to mount up with increasing applied voltage and followed an exponential trend. Numerical simulations were performed to simulate the concentrated electric field strength inside the nanopore and a field strength of 14 kV cm(-1) (at 600 mV applied voltage) was achieved at the pore center. The electric field strength inside the nanopore is much higher than the field strength known to cause deformation of 15-30 μm giant membrane vesicles. As a control, we also performed experiments with rigid polystyrene beads that did not show any deformation during translocation events, which further established our hypothesis of co-translocational deformation of liposomes. Our technique presents an innovative and high throughput means for investigating deformation behavior of soft nano-vesicles.

  8. Measuring High Speed Deformation for Space Applications

    NASA Technical Reports Server (NTRS)

    Wentzel, Daniel

    2014-01-01

    PDV (Photonic Doppler Velocimetry) has proven to be a reliable and versatile technique to observe rapid deformation of frangible joints. It will be a valuable technique in order to understand the physics of two-stage light gas guns and the material response to hypervelocity impact.

  9. Effect of Purity Levels on the High-Temperature Deformation Characteristics of Severely Deformed Titanium

    NASA Astrophysics Data System (ADS)

    Sajadifar, Seyed Vahid; Yapici, Guney Guven

    2017-01-01

    In the present investigation, high-temperature compression tests were conducted at strain rates of 0.001 to 0.1 s-1 and at temperatures of 873 K to 1173 K (600 °C to 900 °C) in order to study the hot deformation characteristics and dynamic softening mechanisms of two different grades of commercial purity titanium after severe plastic deformation. It was observed that the effects of deformation rate and temperature are significant on obtained flow stress curves of both grades. Higher compressive strength exhibited by grade 2 titanium at relatively lower deformation temperatures was attributed to the grain boundary characteristics in relation with its lower processing temperature. However, severely deformed grade 4 titanium demonstrated higher compressive strength at relatively higher deformation temperatures (above 800 °C) due to suppressed grain growth via oxygen segregation limiting grain boundary motion. Constitutive equations were established to model the flow behavior, and the validity of the predictions was demonstrated with decent agreement accompanied by average error levels less than 5 pct for all the deformation conditions.

  10. Effect of Purity Levels on the High-Temperature Deformation Characteristics of Severely Deformed Titanium

    NASA Astrophysics Data System (ADS)

    Sajadifar, Seyed Vahid; Yapici, Guney Guven

    2017-03-01

    In the present investigation, high-temperature compression tests were conducted at strain rates of 0.001 to 0.1 s-1 and at temperatures of 873 K to 1173 K (600 °C to 900 °C) in order to study the hot deformation characteristics and dynamic softening mechanisms of two different grades of commercial purity titanium after severe plastic deformation. It was observed that the effects of deformation rate and temperature are significant on obtained flow stress curves of both grades. Higher compressive strength exhibited by grade 2 titanium at relatively lower deformation temperatures was attributed to the grain boundary characteristics in relation with its lower processing temperature. However, severely deformed grade 4 titanium demonstrated higher compressive strength at relatively higher deformation temperatures (above 800 °C) due to suppressed grain growth via oxygen segregation limiting grain boundary motion. Constitutive equations were established to model the flow behavior, and the validity of the predictions was demonstrated with decent agreement accompanied by average error levels less than 5 pct for all the deformation conditions.

  11. Modelling highly deformable metal extrusion using SPH

    NASA Astrophysics Data System (ADS)

    Prakash, Mahesh; Cleary, Paul W.

    2015-05-01

    Computational modelling is often used to reduce trial extrusions through accurate defect prediction. Traditionally, metal extrusion is modelled using mesh based finite element methods. However, large plastic deformations can lead to heavy re-meshing and numerical diffusion. Here we use the mesh-less smoothed particle hydrodynamics method since it allows simulation of large deformations without re-meshing and the tracking of history dependent properties such as plastic strain making it suitable for defect prediction. The variation in plastic strain and deformation for aluminium alloy in a cylindrical 3D geometry with extrusion ratio and die angle is evaluated. The extrusion process is found to have three distinct phases consisting of an initial sharp rise in extrusion force, a steady phase requiring constant force and terminating in a sharp decline in force as metal is completely extruded. Deformation and plastic strain increased significantly with extrusion ratio but only moderately with die angle. Extrusion force increased by 150 % as the extrusion ratio increased from 2:1 to 4:1 but had only a marginal change with die angle. A low strain zone in the centre of the extruded product was found to be a function of extrusion ratio but was persistent and did not vary with die angle. Simulation of a complex 3D building industry component showed large variations in plastic strain along the length of the product at two scales. These were due to change in metal behaviour as extrusion progressed from phase 1 to phase 2. A stagnation zone at the back of the die was predicted that could lead to the "funnel" or "pipe" defect.

  12. Continuous deformation versus episodic deformation at high stress - the microstructural record

    NASA Astrophysics Data System (ADS)

    Trepmann, C. A.; Stöckhert, B.

    2009-04-01

    The microstructural record of continuous high stress deformation is compared to that of episodic high stress deformation on two examples: 1. Folding of quartz veins in metagreywacke from Pacheco Pass, California, undergoing deformation by dissolution precipitation creep at temperatures of 300 ± 50°C. The microfabric of the folded quartz veins indicates deformation by dislocation creep accompanied by subgrain rotation. The small recrystallized grain size of ~8±6 µm in average implies relatively high differential stresses of a few hundred MPa. The stress concentration in the vein is due to a high contrast in effective viscosities between the single phase material and the polyphase fine-grained host metagreywacke deforming by dissolution precipitation creep. Smoothly curved, but generally not sutured, grain boundaries as well as the small size and a relatively high dislocation density of recrystallized grains suggest that strain-induced grain boundary migration was of minor importance. This is suspected to be a consequence of low strain gradients, which are due to the relative rates of dynamic recovery and continuous dislocation production during climb-controlled creep, at high stress and the given low temperature. Subgrain rotation recrystallization is thus proposed to be characteristic for continuous deformation at high differential stress. 2. Episodic deformation in the middle crust at the tip of a seismic active fault zone. The microfabric of mid-crustal rocks exhumed in tectonically active regions can record episodic high stress deformation at the base of the seismogenic layer. The quartz veins from St. Paul la Roche in the Massif Central, France, are very coarse grained. On the scale of a thin section they are basically single crystalline. However, they show a very heterogeneous microstructure with a system of healed microcracks that are decorated by subgrains and more rarely by small recrystallized grains. Undulating deformation lamellae that do not show a

  13. Phenomenological model for transient deformation based on state variables

    SciTech Connect

    Jackson, M S; Cho, C W; Alexopoulos, P; Mughrabi, H; Li, C Y

    1980-01-01

    The state variable theory of Hart, while providing a unified description of plasticity-dominated deformation, exhibits deficiencies when it is applied to transient deformation phenomena at stresses below yield. It appears that the description of stored anelastic strain is oversimplified. Consideration of a simple physical picture based on continuum dislocation pileups suggests that the neglect of weak barriers to dislocation motion is the source of these inadequacies. An appropriately modified description incorporating such barriers then allows the construction of a macroscopic model including transient effects. Although the flow relations for the microplastic element required in the new theory are not known, tentative assignments may be made for such functions. The model then exhibits qualitatively correct behavior when tensile, loading-unloading, reverse loading, and load relaxation tests are simulated. Experimental procedures are described for determining the unknown parameters and functions in the new model.

  14. Deformation Twinning of a Silver Nanocrystal under High Pressure

    SciTech Connect

    Huang, Xiaojing; Yang, Wenge; Harder, Ross; Sun, Yugang; Liu, Ming; Chu, Yong S.; Robinson, Ian K.; Mao, Ho-kwang

    2015-11-01

    Within a high-pressure environment, crystal deformation is controlled by complex processes such as dislocation motion, twinning, and phase transitions, which change materials' microscopic morphology and alter their properties. Understanding a crystal's response to external stress provides a unique opportunity for rational tailoring of its functionalities. It is very challenging to track the strain evolution and physical deformation from a single nanoscale crystal under high-pressure stress. Here, we report an in situ three-dimensional mapping of morphology and strain evolutions in a single-crystal silver nanocube within a high-pressure environment using the Bragg Coherent Diffractive Imaging (CDI) method. We observed a continuous lattice distortion, followed by a deformation twining process at a constant pressure. The ability to visualize stress-introduced deformation of nanocrystals with high spatial resolution and prominent strain sensitivity provides an important route for interpreting and engineering novel properties of nanomaterials.

  15. Dislocation models of interseismic deformation in the western United States

    USGS Publications Warehouse

    Pollitz, F.F.; McCrory, P.; Svarc, J.; Murray, J.

    2008-01-01

    The GPS-derived crustal velocity field of the western United States is used to construct dislocation models in a viscoelastic medium of interseismic crustal deformation. The interseismic velocity field is constrained by 1052 GPS velocity vectors spanning the ???2500-km-long plate boundary zone adjacent to the San Andreas fault and Cascadia subduction zone and extending ???1000 km into the plate interior. The GPS data set is compiled from U.S. Geological Survey campaign data, Plate Boundary Observatory data, and the Western U.S. Cordillera velocity field of Bennett et al. (1999). In the context of viscoelastic cycle models of postearthquake deformation, the interseismic velocity field is modeled with a combination of earthquake sources on ???100 known faults plus broadly distributed sources. Models that best explain the observed interseismic velocity field include the contributions of viscoelastic relaxation from faulting near the major plate margins, viscoelastic relaxation from distributed faulting in the plate interior, as well as lateral variations in depth-averaged rigidity in the elastic lithosphere. Resulting rigidity variations are consistent with reduced effective elastic plate thickness in a zone a few tens of kilometers wide surrounding the San Andreas fault (SAF) system. Primary deformation characteristics are captured along the entire SAF system, Eastern California Shear Zone, Walker Lane, the Mendocino triple junction, the Cascadia margin, and the plate interior up to ???1000 km from the major plate boundaries.

  16. Direct state reconstruction with coupling-deformed pointer observables

    NASA Astrophysics Data System (ADS)

    Zhu, Xuanmin; Zhang, Yu-Xiang; Wu, Shengjun

    2016-06-01

    Direct state tomography (DST) using weak measurements has received wide attention. Based on the concept of coupling-deformed pointer observables presented by Zhang et al. [Y.-X. Zhang, S. Wu, and Z.-B. Chen, Phys. Rev. A 93, 032128 (2016), 10.1103/PhysRevA.93.032128], a modified direct state tomography (MDST) is proposed, examined, and compared with other typical state tomography schemes. MDST has exact validity for measurements of any strength. We identify the strength needed to attain the highest efficiency level of MDST by using statistical theory. MDST is much more efficient than DST in the sense that far fewer samples are needed to reach DST's level of reconstruction accuracy. Moreover, MDST has no inherent bias when compared to DST.

  17. Deformed band structures at high spin in 200Tl

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Soumik; Bhattacharyya, S.; Das Gupta, S.; Pai, H.; Mukherjee, G.; Palit, R.; Xu, F. R.; Wu, Q.; Shrivastava, A.; Asgar, Md. A.; Banik, R.; Bhattacharjee, T.; Chanda, S.; Chatterjee, A.; Goswami, A.; Nanal, V.; Pandit, S. K.; Saha, S.; Sethi, J.; Roy, T.; Thakur, S.

    2017-01-01

    High-spin band structures of 200Tl have been studied by γ -ray spectroscopic methods using the 198Pt(7Li,5 n )200Tl reaction at 45 MeV of beam energy. The level scheme of 200Tl has been extended significantly and several new band structures have been established with the observation of 60 new transitions. The π h9 /2⊗ν i13 /2 oblate band has been extended beyond the particle alignment frequencies. The band structures and the other excited states have been compared with the neighboring odd-odd Tl isotopes. Total Routhian surface calculations have been performed to study the deformation and shape changes as a function of spin in this nucleus. These calculations could reproduce the particle alignment frequency and suggest that the neutron pair alignment in ν i13 /2 orbital induces γ softness in 200Tl.

  18. High-actuator-count MEMS deformable mirrors

    NASA Astrophysics Data System (ADS)

    Helmbrecht, Michael A.; He, Min; Kempf, Carl J.

    2013-05-01

    Adaptive optics (AO) technology has enabled dramatic improvement in imaging performance for fields spanning astronomy, defense, microscopy, and retinal imaging. A critical component within the AO systems is the deformable mirror (DM) that implements the actual wavefront correction. This paper introduces the Iris AO segmented MEMS DM technology with an overview of the fabrication process and a description of the DM operation. The paper demonstrates correction capabilities of 111 and 489 actuator DMs and describes recent effort for scaling to 1000-actuator class DMs. Finally, the paper presents laser testing results of dielectric coated DMs and describes the development path for MEMS DMs capable of 2.8 kW/cm2 average laser power.

  19. Plastic deformation and sintering of alumina under high pressure

    SciTech Connect

    Liu, Fangming; Liu, Pingping; Wang, Haikuo; Xu, Chao; Yin, Shuai; Yin, Wenwen; Li, Yong; He, Duanwei

    2013-12-21

    Plastic deformation of alumina (Al{sub 2}O{sub 3}) under high pressure was investigated by observing the shape changes of spherical particles, and the near fully dense transparent bulks were prepared at around 5.5 GPa and 900 °C. Through analyzing the deformation features, densities, and residual micro-strain of the Al{sub 2}O{sub 3} compacts prepared under high pressures and temperatures (2.0–5.5 GPa and 600–1200 °C), the effects of plastic deformation on the sintering behavior of alumina have been demonstrated. Under compression, the microscopic deviatoric stress caused by grain-to-grain contact could initiate the plastic deformation of individual particles, eliminate pores of the polycrystalline samples, and enhance the local atomic diffusion at the grain boundaries, thus produced transparent alumina bulks.

  20. Simulation of erythrocyte deformation in a high shear flow.

    PubMed

    Nakamura, Masanori; Bessho, Sadao; Wada, Shigeo

    2009-01-01

    Deformation of a red blood cell (RBC) in a high-shear flow was investigated. The RBC was modeled as a closed shell membrane consisting of spring networks in the framework of the energy minimum concept. The simulation of RBC in a parallel shear flow showed deformation parameters of RBC were well agreed with experimental results. The simulation of RBC behavior in various flow fields demonstrated that the shape was determined not only by instantaneous fluid force acting on it but also its deformation history. No consistency was found between the maximum of the first principal strain and conventionally used hemolysis index. Those results addressed the importance of considering an RBC deformation for accurately predicting hemolysis.

  1. Novel high-bandwidth bimorph deformable mirrors

    NASA Astrophysics Data System (ADS)

    Griffith, Michael S.; Laycock, Leslie C.; Archer, Nick J.

    2004-12-01

    Adaptive Optics (AO) is a critical underpinning technology for future laser delivery (including free-space optical communications), target illumination and imaging systems. It measures and compensates for optical distortion caused by transmission through the atmosphere, resulting in the ability to deploy smaller lasers and identify targets at greater ranges. One of the key components in an AO system is the wavefront modifier, which acts on the incoming or outgoing beam to counter the effects of the atmosphere. BAE SYSTEMS Advanced Technology Centre is developing multi-element bimorph deformable mirrors for such an applications. Our initial designs were based on a standard construction and exhibited a resonant frequency of 1kHz with a maximum stroke of +/-20μm for an active aperture of 50mm. These devices were limited by the necessity to have a 'dead space' between the inner active area and the mirror boundary; this ensured that both the requirements for the stroke and the fixed boundary conditions could be met simultaneously. However, there was a significant penalty to pay in terms of bandwidth, which is inversely proportional to the square of the full mirror diameter. In a series of iteration steps, we have created novel mounting arrangements that reduce dead space and thus provide the optimum trade-off between bandwidth and stroke. These schemes include supporting the mirror from underneath, rather than at its edge. As a result, models of 60mm active diameter mirrors predict a resonance in excess of 5kHz, combined with a maximum stroke greater than +/-40μm. This paper will discuss a number of different mirror designs and present experimental results for recently assembled devices.

  2. Calculation of the spectrum of {gamma} rays connecting superdeformed and normally deformed nuclear states

    SciTech Connect

    Dossing, T.; Khoo, T.L.; Lauritsen, T.

    1995-08-01

    The decay out of superdeformed states occurs by coupling to compound nuclear states of normal deformation. The coupling is very weak, resulting in mixing of the SD state with one or two normal compound states. With a high energy available for decay, a statistical spectrum ensues. The shape of this statistical spectrum contains information on the level densities of the excited states below the SD level. The level densities are sensitively affected by the pair correlations. Thus decay-out of a SD state (which presents us with a means to start a statistical cascade from a highly-excited sharp state) provides a method for investigating the reduction of pairing with increasing thermal excitation energy.

  3. Nanostructural states in Nb-Al mechanocomposite after combined deformation treatment

    SciTech Connect

    Ditenberg, Ivan A. Denisov, Konstantin I.; Tyumentsev, Alexander N.; Korchagin, Michail A.; Korznikov, Alexander V.

    2015-10-27

    Nanostructural states were investigated, that were formed in Nb-Al system-based mechanocomposite after combined deformation treatment that includes mechanical activation in a planetary ball mill and subsequent consolidation by torsion under pressure on Bridgman anvils. The formation of the layered structure, consisting of Nb and Al nanobands with width from several to several tens of nanometers was revealed. The structural states with high elastic curvature of crystal lattice and high level of local internal stresses found in Nb and Al subgrains were investigated by transmission electron microscopy.

  4. High Resolution Rapid Revisits Insar Monitoring of Surface Deformation

    NASA Astrophysics Data System (ADS)

    Singhroy, V.; Li, J.; Charbonneau, F.

    2014-12-01

    Monitoring surface deformation on strategic energy and transportation corridors requires high resolution spatial and temporal InSAR images for mitigation and safety purposes. High resolution air photos, lidar and other satellite images are very useful in areas where the landslides can be fatal. Recently, radar interferometry (InSAR) techniques using more rapid revisit images from several radar satellites are increasingly being used in active deformation monitoring. The Canadian RADARSAT Constellation (RCM) is a three-satellite mission that will provide rapid revisits of four days interferometric (InSAR) capabilities that will be very useful for complex deformation monitoring. For instance, the monitoring of surface deformation due to permafrost activity, complex rock slide motion and steam assisted oil extraction will benefit from this new rapid revisit capability. This paper provide examples of how the high resolution (1-3 m) rapid revisit InSAR capabilities will improve our monitoring of surface deformation and provide insights in understanding triggering mechanisms. We analysed over a hundred high resolution InSAR images over a two year period on three geologically different sites with various configurations of topography, geomorphology, and geology conditions. We show from our analysis that the more frequent InSAR acquisitions are providing more information in understanding the rates of movement and failure process of permafrost triggered retrogressive thaw flows; the complex motion of an asymmetrical wedge failure of an active rock slide and the identification of over pressure zones related to oil extraction using steam injection. Keywords: High resolution, InSAR, rapid revisits, triggering mechanisms, oil extraction.

  5. Microfabric development in dunite during high stress deformation and subsequent recrystallization

    NASA Astrophysics Data System (ADS)

    Trepmann, Claudia; Druiventak, Anthony; Matysiak, Agnes; Renner, Jörg

    2010-05-01

    The microfabric development in dunite is analyzed in non-steady state deformation and annealing experiments, which are designed to simulate earthquake-driven episodic creep in the upper mantle of the oceanic lithosphere at the base of the seismogenic zone. The samples are deformed in a servohydraulically-controlled solid medium deformation apparatus at a temperature of 600°C, a constant strain rate of 10-4s-1 (kick) and a confining pressure of 1.0 GPa. In some experiments deformation is followed by annealing for 15 h to 70 h at zero nominal differential stress, temperatures of 800°C to 1000°C (kick & cook) and 2.0 GPa confining pressure. We use coarse-grained dunite from the Almklovdalen peridotite complex (Western Norway) as starting material. The dunite comprises ca. 90% olivine, <10% orthopyroxene and small amounts of spinel and chlorite. The kick experiments yield maximum differential stress of ca. 1 GPa and < 20% of permanent strain. The resulting microfabrics are analysed by optical and electron microscopic techniques. Intragranular microcracks and micro-shear zones in olivine, which can be crystallographically controlled, developed during deformation. After annealing at 1000°C, the microfabric is characterized by very fine-grained recrystallized olivine grains with an average diameter of ca. 5 µm. The recrystallized grains are arranged along micro-shear zones and occur in aggregates surrounding olivine porphyroclasts. The area fraction of recrystallized grains is varying but generally smaller than 20%. The microfabrics from our experiments compare well with microfabrics observed from naturally deformed peridotites of the Baldissero, Balmuccia and Finero complexes in the Western Alps. Similar olivine recrystallization aggregates in naturally deformed peridotites are frequently interpreted as indicative of deformation by dislocation or diffusion creep. The microfabrics of our kick & cook experiments indicate a development through an initial stage of high

  6. Beam quality active control of a slab MOPA solid state laser with combined deformable mirrors

    NASA Astrophysics Data System (ADS)

    Xiang, Rujian; Xu, Honglai; Li, Guohui; Wu, Jing; Du, Yinglei; Zhang, Kai

    2017-01-01

    A novel phase aberration correcting method based on combined deformable mirrors (DMs) in a slab MOPA (master oscillator and power amplifier) solid state laser system is proposed and validated experimentally. The adaptive optics(AO) system with combined deformable mirrors composed of a one-dimension (1D) DM with 11 actuators and a two-dimension (2D) DM with 67 valid actuators, has been designed to correct the phase aberrations, which doesn't need the high voltage drivers and has an excellent correcting efficiency of the high order phase aberrations. The experimental results show that the wave front of the slab laser beam is compensated well and the residual wave front is less than 0.08 λ rms. The beam quality of the slab laser in the far field is improved to1.67x DL.

  7. HIGH-CONTRAST IMAGING VIA MODAL CONVERGENCE OF DEFORMABLE MIRROR

    SciTech Connect

    Wang Feiling

    2012-06-01

    For extremely high contrast imaging, such as direct observation of faint stellar companions, an adaptive optics system is required to produce low-halo and low-speckle regions in the focal plane. A method for deformable mirror control is proposed to achieve this goal. The method relies on a modal convergence of the deformable mirror driven by a focal-plane metric. The modal sets are derived from the Walsh functions. The Walsh-function modes serve two purposes: the expansion of the actuator displacements and the expansion of the phase functions. Taking advantage of the unique properties of the modal functions, a universal control algorithm is devised for the realization of high-contrast focal planes with and without the help of conventional coronagraphy. Numerical modeling is conducted to simulate complete imaging systems under various scenarios. It is shown that the proposed method reliably produces high-contrast focal planes using either a segmented or a membrane mirror. In the presence of random aberration the method is shown to be able to maintain high-contrast focal planes. Requiring neither retrieval of electric fields nor detailed knowledge of the deformable mirrors, this technique may allow high-contrast imaging in real time.

  8. Bone Ingrowth to Ti Fibre Knit Block with High Deformability

    PubMed Central

    Henmi, Yoko; Jimbo, Ryo; Jinno, Yohei; Sekine, Kazumitsu; Hamada, Kenichi

    2016-01-01

    ABSTRACT Objectives The objective of this study is to develop a Ti fibre knit block without sintering, and to evaluate its deformability and new bone formation in vivo. Material and Methods A Ti fibre with a diameter of 150 μm was knitted to fabricate a Ti mesh tube. The mesh tube was compressed in a metal mould to fabricate porous Ti fibre knit blocks with three different porosities of 88%, 69%, and 50%. The elastic modulus and deformability were evaluated using a compression test. The knit block was implanted into bone defects of a rabbit’s hind limb, and new bone formation was evaluated using micro computed tomography (micro-CT) analysis and histological analysis. Results The knit blocks with 88% porosity showed excellent deformability, indicating potential appropriateness for bone defect filling. Although the porosities of the knit block were different, they indicated similar elastic modulus smaller than 1 GPa. The elastic modulus after deformation increased linearly as the applied compression stress increased. The micro-CT analysis indicated that in the block with 50% porosity new bone filled nearly all of the pore volume four weeks after implantation. In contrast, in the block with 88% porosity, new bone filled less than half of the pore volume even 12 weeks after implantation. The histological analysis also indicated new bone formation in the block. Conclusions The titanium fibre knit block with high porosity is potentially appropriate for bone defect filling, indicating good bone ingrowth after porosity reduction with applied compression. PMID:28154746

  9. Effect of deformation on the structural state of piracetam

    NASA Astrophysics Data System (ADS)

    Kanunnikova, O. M.; Mikhailova, S. S.; Karban', O. V.; Mukhgalin, V. V.; Aksenova, V. V.; Sen'kovskii, B. V.; Pechina, E. A.; Lad'yanov, V. I.

    2016-04-01

    The effect of various deformation actions on the structure-phase transformations in piracetam of modifications I and II with a sodium acetate addition is studied. Mechanical activation and pressing are shown to cause the polymorphic transformation of modification I into modification II, and modification III forms predominantly during severe plastic deformation by torsion. The structural difference between the piracetam molecules of modifications I and II is found to be retained in aqueous solutions.

  10. Deformation of Single Crystal Molybdenum at High Pressure

    SciTech Connect

    Bonner, B P; Aracne, C; Farber, D L; Boro, C O; Lassila, D H

    2004-02-24

    Single crystal samples of micron dimensions oriented in the [001] direction were shortened 10 to 40% in uniaxial compression with superposed hydrostatic pressure to begin investigation of how the onset of yielding evolves with pressure. A testing machine based on opposed anvil geometry with precision pneumatic control of the applied force and capability to measure sub micron displacements was developed to produce shape changing deformation at pressure. The experiments extend observations of pressure dependent deformation to {approx}5Gpa at shortening rates of {approx}2*10{sup -4}. Samples have been recovered for post run characterization and analysis to determine if deformation mechanisms are altered by pressure. Experiments under hydrostatic pressure provide insight into the nature of materials under extreme conditions, and also provide a means for altering deformation behavior in a controlled fashion. The approach has a long history demonstrating that pressure enhances ductility in general, and produces enhanced hardening relative to that expected from normal cold work in the BCC metals Mo, Ta and Nb{sup 2}. The pressure hardening is in excess of that predicted from the measured increase in shear modulus at pressure, and therefore is likely due to a dislocation mechanism, such as suppression of kink pair formation or the interaction of forest dislocation cores, and not from lattice resistance. The effect has not been observed in FCC metals, suggesting a fundamental difference between deformation mechanisms at pressure for the two classes. The purpose of this letter is to investigate the origin of pressure hardening with new experiments that extend the pressure range beyond 3 GPa, the upper limit of conventional large sample (1cm{sup 3}) testing methods. Most previous high pressure deformation studies have been on poly crystals, relying on model dependent analysis to infer the maximum deviatoric stress that a deformed sample can support. In one experiment, a

  11. Uniaxial plastic deformation of isotactic polypropylene studied by solid-state NMR

    NASA Astrophysics Data System (ADS)

    Kang, Jia

    At alleviated temperatures, some semicrystralline polymers can be stretched to very large deformation ratios. Such deformations of semicrystalline polymers have been extensively studied since 1960s. Based on experimental observations and theoretical investigations, solid-state transformation (three stage model) proposed in 1971 and local melting and recrystallization in 1978 have been considered two major mechanisms to explain the deformations of polymer crystals. With the elucidation of molecular dynamics in the last two decades, it was proposed in 1999 that helical jump motion plays an important role in crystal deformation. On the other hand, the new structures induced by deformation also influence the molecular motions and resultant properties of deformed polymers. Such processing-structure-property relationship is very important to understand the polymer behaviors as well as to inform the polymer industry. In this dissertation, using the advanced tool of solid-state NMR (ss-NMR), we achieve three goals: Firstly, we investigate the hierarchical crystalline structural changes of isotactic polypropylene (i PP) upon high temperature stretching to understand the deformation process. Secondly, we evaluate the roles of local packing structure and crystal thickness in determining the stem motions and thermal properties of deformed alpha-form iPP. Thirdly, we utilize 13C-labeled isotactic polypropylene (iPP) to trace the change of chain folding number as a function of e to conclude molecular-level deformation mechanism. To realize the first and second goals, the chain packing, crystal thickness, molecular dynamics, and melting temperature (Tm) of a-form iPP drawn uniaxially at high temperatures of 100 - 150 °C were investigated using solid-state (SS) NMR and DSC. Two types of iPP samples with disordered (alpha1) and relatively ordered (alpha2-rich) packing structures were prepared via different thermal treatments and drawn up to an engineering strain ( e) of

  12. Microstructure Evolution in Alpha Iron during High Temperature Tensile Deformation

    NASA Astrophysics Data System (ADS)

    Thanh, Phi Hung Xuan

    The microstructural evolution of alpha iron under tensile deformation at high temperature (TH 0.5) and slow strain-rate (10-5 s-1 to 10-5 s-1) was investigated. The impetus for this study was the recent observation of Dynamic Abnormal Grain Growth (DAGG) in pure molybdenum under the same testing conditions. A high temperature tensile testing system was refurbished and assembled for this study. The testing system consists of an Centorr 2229 furnace system mounted on an Instron 1331 load frame. I designed the tensile grip and programmed the testing program to obtain data in the stress and strain regime of interest. Testing were done at both UC Davis and Los Alamos National Labs (LANL). Metallography techniques and electron backscattering diffraction (EBSD) technique in a scanning electron microscope were used to characterize the samples after testing. In addition to normal tensile tests at constant strain-rates where DAGG is proposed to occur, a series of strain-rate change tests were designed and performed. Strain-rate change tests were employed to extract activation area information that provided insight into the active mechanism of deformation of the material in addition to the information obtained from analysis of the stress-strain curve and the microstructure via optical microscopy and EBSD. The obtained stress-train curve data were compared with the stress-strain curves data in the literature for alpha iron in similar regime of deformation indicating that the dominant mechanism of deformation is dynamic recovery. The comparison includes past stress-strain curves and the data recorded in the Ashby Map. Optical and EBSD analysis showed that normal grain growth occurred in alpha iron during this testing regime. This lack of grain boundary pinning by impurity differs from that observed in Mo that exhibited DAGG. Activation area analysis showed that the activation area values of Fe are consistent with friction drag from the lattice being the active deformation

  13. Modeling Large-Strain, High-Rate Deformation in Metals

    SciTech Connect

    Lesuer, D R; Kay, G J; LeBlanc, M M

    2001-07-20

    The large strain deformation response of 6061-T6 and Ti-6Al-4V has been evaluated over a range in strain rates from 10{sup -4} s{sup -1} to over 10{sup 4} s{sup -1}. The results have been used to critically evaluate the strength and damage components of the Johnson-Cook (JC) material model. A new model that addresses the shortcomings of the JC model was then developed and evaluated. The model is derived from the rate equations that represent deformation mechanisms active during moderate and high rate loading. Another model that accounts for the influence of void formation on yield and flow behavior of a ductile metal (the Gurson model) was also evaluated. The characteristics and predictive capabilities of these models are reviewed.

  14. Ultrasound Velocity Measurements in High-Chromium Steel Under Plastic Deformation

    NASA Astrophysics Data System (ADS)

    Lunev, Aleksey; Bochkareva, Anna; Barannikova, Svetlana; Zuev, Lev

    2016-04-01

    In the present study, the variation of the propagation velocity of ultrasound in the plastic deformation of corrosion-resistant high-chromium steel 40X13 with ferrite-carbide (delivery status), martensitic (quenched) and sorbitol (after high-temperature tempering) structures have beem studied/ It is found that each state shows its view of the loading curve. In the delivery state diagram loading is substantially parabolic throughout, while in the martensitic state contains only linear strain hardening step and in the sorbitol state the plastic flow curve is three-step. The velocity of ultrasonic surface waves (Rayleigh waves) was measured simultaneously with the registration of the loading curve in the investigated steel in tension. It is shown that the dependence of the velocity of ultrasound in active loading is determined by the law of plastic flow, that is, the staging of the corresponding diagram of loading. Structural state of the investigated steel is not only changing the type of the deformation curve under uniaxial tension, but also changes the nature of ultrasound speed of deformation.

  15. Measurement of high viscosity with laser induced surface deformation technique

    SciTech Connect

    Yoshitake, Y.; Mitani, S.; Sakai, K.; Takagi, K.

    2005-01-15

    A technique for viscosity measurement was developed based on the principle of laser-induced surface deformation. Light incident into liquids increases its momentum due to the difference in refractive index and gives the surface an upward force as a reaction. The plane surface thus swells up and deforms, and the shape is determined so that the force is balanced with the surface tension and the gravity. On sudden laser irradiation, the deformation inevitably accompanies a viscous flow and exhibits a relaxational behavior with a delay time, which gives the viscosity. Theoretical prediction of the step-response function was given that takes surface tension waves excited by the laser into consideration. Nd-yttritium-aluminum-garnet laser with 0.6 W output was focused to {approx}200 {mu}m beam waist and used for the pumping. The deformation process was observed sensitively with another probe laser illuminating the activated area. This system was tested with the standard liquids for viscosity ranging from 1 to 10{sup 6} cSt. The results demonstrated the validity of this technique, though a correction for the inertia effect was needed in the range lower than 10 cSt. Further, effect of the thermal expansion by a slight optical absorption was discussed. This technique is especially useful at high viscosities since the measurement takes only a few seconds even in the specimen with 10{sup 6} cSt. Besides the rapidity, it has a great advantage of a noncontact feature and is appropriate for measuring the liquids that strongly dislike contamination. It has also potential applications in industries, measurement of liquids isolated in a production line, for instance.

  16. High Shear Deformation to Produce High Strength and Energy Absorption in Mg Alloys

    SciTech Connect

    Joshi, Vineet V.; Jana, Saumyadeep; Li, Dongsheng; Garmestani, Hamid; Nyberg, Eric A.; Lavender, Curt A.

    2014-02-01

    Magnesium alloys have the potential to reduce the mass of transportation systems however to fully realize the benefits it must be usable in more applications including those that require higher strength and ductility. It has been known that fine grain size in Mg alloys leads to high strength and ductility. However, the challenge is how to achieve this optimal microstructure in a cost effective way. This work has shown that by using optimized high shear deformation and second phase particles of Mg2Si and MgxZnZry the energy absorption of the extrusions can exceed that of AA6061. The extrusion process under development described in this presentation appears to be scalable and cost effective. In addition to process development a novel modeling approach to understand the roles of strain and state-of-strain on particle fracture and grain size control has been developed

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

    SciTech Connect

    Seregin, G.V.; Efimenko, L.L.; Leonov, M.V.

    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.

  18. High Pressure Experimental Deformation in Talc Assemblies: Cheap, Easy, Wrong

    NASA Astrophysics Data System (ADS)

    Stewart, E. D.; Holyoke, C. W.; Kronenberg, A. K.; Newman, J.

    2011-12-01

    Early methods of applying high pressures in the Griggs piston-cylinder triaxial deformation apparatus employed solid confining media thought to be weak compared with the silicate samples under investigation. Griggs apparatus sample assemblies with talc as the confining medium have been used in large numbers of experimental studies of rock deformation at pressures of 1.0 to 2.0 GPa. Modern methods now use solid and molten salts as confining media, with flow strengths that are low for solid salts (at elevated temperatures) and zero for molten salts; yet, talc continues to be used when deformation microstructures are used to infer differential stress. Recent comparison experiments conducted in the Griggs apparatus and gas apparatus have yielded calibrations that enable accurate stress measurements using solid and molten salt assemblies. These calibrations demonstrate that differential stresses measured at high confining pressures using the Griggs apparatus are systematically high, yet they are correctable. They also indicate that a significant portion of the required stress correction is due to friction in the nested loading column of the apparatus. No other correction is required for molten salt assemblies and the offset in stress measurements using solid salt assemblies, due to the strength of solid salt, is considerably smaller than previously thought. Encouraged by these calibrations for solid and molten salt assemblies, we performed similar comparison experiments in the Griggs apparatus using traditional, easy-to-use talc assemblies with the goal of developing another calibration for high-pressure stress measurements. Following the same procedures as used in our earlier calibrations, we deformed molybdenum and TZM alloy cylinders using a talc assembly at the same temperatures and strain rates (600-1000{circ}C and 1{ast}10^{-4}/s) as used in gas apparatus experiments. The apparent strengths of the samples deformed below the talc dehydration temperature were at

  19. 3D High Resolution Mesh Deformation Based on Multi Library Wavelet Neural Network Architecture

    NASA Astrophysics Data System (ADS)

    Dhibi, Naziha; Elkefi, Akram; Bellil, Wajdi; Amar, Chokri Ben

    2016-12-01

    This paper deals with the features of a novel technique for large Laplacian boundary deformations using estimated rotations. The proposed method is based on a Multi Library Wavelet Neural Network structure founded on several mother wavelet families (MLWNN). The objective is to align features of mesh and minimize distortion with a fixed feature that minimizes the sum of the distances between all corresponding vertices. New mesh deformation method worked in the domain of Region of Interest (ROI). Our approach computes deformed ROI, updates and optimizes it to align features of mesh based on MLWNN and spherical parameterization configuration. This structure has the advantage of constructing the network by several mother wavelets to solve high dimensions problem using the best wavelet mother that models the signal better. The simulation test achieved the robustness and speed considerations when developing deformation methodologies. The Mean-Square Error and the ratio of deformation are low compared to other works from the state of the art. Our approach minimizes distortions with fixed features to have a well reconstructed object.

  20. Entanglement generation from deformed spin coherent states using a beam splitter

    NASA Astrophysics Data System (ADS)

    Berrada, K.; El Baz, M.; Saif, F.; Hassouni, Y.; Mnia, S.

    2009-07-01

    Using the linear entropy as a measure of entanglement, we investigate the effect of a beam splitter on the Perelomov coherent states for the q-deformed Uq(su(2)) algebra. We distinguish two cases: in the classical q → 1 limit, we find that the states become Glauber coherent states as the spin tends to infinity; whereas for q ≠ 1, the states, contrary to the earlier case, become entangled as they pass through a beam splitter. The entanglement strongly depends on the q-deformation parameter and the amplitude Z of the state.

  1. Analytical Modeling of the High Strain Rate Deformation of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Roberts, Gary D.; Gilat, Amos

    2003-01-01

    The results presented here are part of an ongoing research program to develop strain rate dependent deformation and failure models for the analysis of polymer matrix composites subject to high strain rate impact loads. State variable constitutive equations originally developed for metals have been modified in order to model the nonlinear, strain rate dependent deformation of polymeric matrix materials. To account for the effects of hydrostatic stresses, which are significant in polymers, the classical 5 plasticity theory definitions of effective stress and effective plastic strain are modified by applying variations of the Drucker-Prager yield criterion. To verify the revised formulation, the shear and tensile deformation of a representative toughened epoxy is analyzed across a wide range of strain rates (from quasi-static to high strain rates) and the results are compared to experimentally obtained values. For the analyzed polymers, both the tensile and shear stress-strain curves computed using the analytical model correlate well with values obtained through experimental tests. The polymer constitutive equations are implemented within a strength of materials based micromechanics method to predict the nonlinear, strain rate dependent deformation of polymer matrix composites. In the micromechanics, the unit cell is divided up into a number of independently analyzed slices, and laminate theory is then applied to obtain the effective deformation of the unit cell. The composite mechanics are verified by analyzing the deformation of a representative polymer matrix composite (composed using the representative polymer analyzed for the correlation of the polymer constitutive equations) for several fiber orientation angles across a variety of strain rates. The computed values compare favorably to experimentally obtained results.

  2. Skyrme random-phase-approximation description of lowest Kπ=2γ+ states in axially deformed nuclei

    NASA Astrophysics Data System (ADS)

    Nesterenko, V. O.; Kartavenko, V. G.; Kleinig, W.; Kvasil, J.; Repko, A.; Jolos, R. V.; Reinhard, P.-G.

    2016-03-01

    The lowest quadrupole γ -vibrational Kπ=2+ states in axially deformed rare-earth (Nd, Sm, Gd, Dy, Er, Yb, Hf, W) and actinide (U) nuclei are systematically investigated within the separable random-phase-approximation (SRPA) based on the Skyrme functional. The energies Eγ and reduced transition probabilities B (E 2 ) of 2γ+ states are calculated with the Skyrme forces SV-bas and SkM*. The energies of two-quasiparticle configurations forming the SRPA basis are corrected by using the pairing blocking effect. This results in a systematic downshift of Eγ by 0.3-0.5 MeV and thus in a better agreement with the experiment, especially in Sm, Gd, Dy, Hf, and W regions. For other isotopic chains, a noticeable overestimation of Eγ and too weak collectivity of 2γ+ states still persist. It is shown that domains of nuclei with low and high 2γ+ collectivity are related to the structure of the lowest two-quasiparticle states and conservation of the Nilsson selection rules. The description of 2γ+ states with SV-bas and SkM* is similar in light rare-earth nuclei but deviates in heavier nuclei. However SV-bas much better reproduces the quadrupole deformation and energy of the isoscalar giant quadrupole resonance. The accuracy of SRPA is justified by comparison with exact RPA. The calculations suggest that a further development of the self-consistent calculation schemes is needed for a systematic satisfactory description of the 2γ+ states.

  3. The high-speed deformation behavior of TRIP steels

    NASA Astrophysics Data System (ADS)

    Choi, Ildong; Bruce, Denise M.; Matlock, David K.; Speer, John G.

    2008-04-01

    The high-speed deformation behavior of TRIP steel was investigated at strain rates ranging from 10-2 s-1 to 103 s-1. The effects of metallurgical factors, such as the rolling direction, thickness, and gage length, on the tensile properties at various strain rates were evaluated. The ultimate tensile strength, uniform elongation, strain rate sensitivity, absorbed energy, and strain-hardening exponent are reported. In general, the strength increases and the ductility decreases as the strain rate increases. The samples with a high amount of retained austenite had two distinct regions of strain rate sensitivity, showing high strain rate sensitivity over a strain rate of 102 s-1. The tensile properties were not affected by the gage length and thickness of the tensile samples; however, the rolling direction of the tensile samples affected the UTS values slightly. The absorbed energy of the TRIP steel greatly exceeded that of HSLA steel.

  4. High strain rate deformation of NiAl

    SciTech Connect

    Maloy, S.A.; Gray, G.T. III; Darolia, R.

    1994-07-01

    NiAl is a potential high temperature structural material. Applications for which NiAl is being considered (such as rotating components in jet engines) requires knowledge of mechanical properties over a wide range of strain rates. Single crystal NiAl (stoichiometric and Ni 49.75Al 0.25Fe) has been deformed in compression along [100] at strain rates of 0.001, 0.1/s and 2000/s and temperatures of 76,298 and 773K. <111> slip was observed after 76K testing at a strain rate of 0.001/s and 298K testing at a strain rate of 2000/s. Kinking was observed after deformation at 298K and a strain rate of 0.001/s and sometimes at 298 K and a strain rate of 0.1/s. Strain hardening rates of 8200 and 4000 MPa were observed after 773 and 298K testing respectively, at a strain rate of 2000/s. Results are discussed in reference to resulting dislocation substructure.

  5. Revisiting the deformed high shoreline of Lake Bonneville

    NASA Astrophysics Data System (ADS)

    Chen, Christine Y.; Maloof, Adam C.

    2017-03-01

    Since G. K. Gilbert's foundational work in the eastern Great Basin during the late 1800s, the late Pleistocene Lake Bonneville (30-10 ka) has been recognized as a natural laboratory for various Quaternary studies, including lithospheric deformation due to surface loading and climate-forced water balance changes. Such studies rely on knowledge of the elevations of Lake Bonneville's paleoshoreline features and depositional landforms, which record a complex history of lake level variations induced by deglacial climate change. In this paper, we present (1) a new compilation of 178 elevation measurements of shoreline features marking Lake Bonneville's greatest areal extent measured using high-precision differential GPS (dGPS), and (2) a reconstructed outline of the highest shoreline based on dGPS measurements, submeter-resolution aerial imagery, topographic digital elevation models (DEMs), and field observations. We also (3) devise a simplified classification scheme and method for standardizing shoreline elevation measurement for different shoreline morphologies that includes constraints on the position of the still water level (SWL) relative to each feature type. The deformation pattern described by these shoreline features can help resolve the relative effects of local hydro-isostasy due to the lake load and regional solid earth deflection due to the Laurentide ice sheet, with potential implications for Earth rheology, glacial isostatic adjustment, and eustatic sea level change.

  6. Measuring Crustal Deformation in Europe by High Precision Geodetic VLBI

    NASA Astrophysics Data System (ADS)

    Campbell, J.; Nothnagel, A.; Vennebusch, M.

    2002-06-01

    At the western tip of the Eurasian plate, the European continent is besieged by thrusting and receding neighbour plates causing deformations and ruptures of the Earth's crust evidenced by earthquakes and volcanic outbursts. Measuring the extent and progress of crustal deformation has become one of the primary tasks of geodesists and geophysicists. Realizing that Europe enjoys one of the densest networks of radio telescopes especially equipped for high precision, geodetic VLBI has provided the incentive to organise a campaign of regular geodetic VLBI observations in the European network of fixed radio telescopes. The measurements have been carried out since the late eighties at an average rate of six sessions per year. From these data, site coordinates, baseline length changes and station velocity vectors have been derived with steadily increasing accuracy. The overall picture of the observed present-day site motions emulates quite well the pattern of tectonic motions inferred from the geotectonic setting of central Europe and the western Mediterranean. Interesting details are emerging for horizontal motions of the three stations in Italy, which are strongly affected by the complex interactions between the different tectonic regimes in this area. The accuracy of the vertical components is also improving with increasing length of the observational record, allowing to detect significant trends among the relative vertical motions of the sites. The geodetic VLBI network operations have received supportive funding by the European Union under the 2nd and 4th Framework Programmes.

  7. Time-dependent q-deformed bi-coherent states for generalized uncertainty relations

    NASA Astrophysics Data System (ADS)

    Gouba, Laure

    2015-07-01

    We consider the time-dependent bi-coherent states that are essentially the Gazeau-Klauder coherent states for the two dimensional noncommutative harmonic oscillator. Starting from some q-deformations of the oscillator algebra for which the entire deformed Fock space can be constructed explicitly, we define the q-deformed bi-coherent states. We verify the generalized Heisenberg's uncertainty relations projected onto these states. For the initial value in time, the states are shown to satisfy a generalized version of Heisenberg's uncertainty relations. For the initial value in time and for the parameter of noncommutativity θ = 0, the inequalities are saturated for the simultaneous measurement of the position-momentum observables. When the time evolves, the uncertainty products are different from their values at the initial time and do not always respect the generalized uncertainty relations.

  8. Generalized q-deformed Tamm-Dancoff oscillator algebra and associated coherent states

    SciTech Connect

    Chung, Won Sang; Hounkonnou, Mahouton Norbert Arjika, Sama

    2014-08-15

    In this paper, we propose a full characterization of a generalized q-deformed Tamm-Dancoff oscillator algebra and investigate its main mathematical and physical properties. Specifically, we study its various representations and find the condition satisfied by the deformed q-number to define the algebra structure function. Particular Fock spaces involving finite and infinite dimensions are examined. A deformed calculus is performed as well as a coordinate realization for this algebra. A relevant example is exhibited. Associated coherent states are constructed. Finally, some thermodynamics aspects are computed and discussed.

  9. High-temperature deformation behavior in Sr TiO{sub 3} ceramics.

    SciTech Connect

    Singh, D.; Lorenzo-Martin, M.; Chen, G.; Gutierrez-Mora, F.; Routbort, J. L.; Nuclear Engineering Division; Univ. de Sevilla

    2007-01-01

    The high-temperature deformation behavior of a polycrystalline strontium titanate (SrTiO{sub 3}) ceramic (6 {micro}m grain size) was investigated at temperatures of 1200-1345 C in an argon atmosphere. Compressive deformation tests were conducted at strain rates ranging from 5 x 10{sup -6} to 5 x 10{sup -5} s{sup -1}. Steady-state flow stresses were 0.05-30 MPa and increased with increasing strain rates. Stress exponents of {approx}1, at temperatures >1200 C, indicated a viscous diffusion-controlled deformation with an activation energy of {approx}628 {+-} 24 kJ/mol. Comparison of activation energy with literature data suggests diffusion of cations as the rate-controlling mechanism. Absence of cavitation and grain-shape changes were consistent with grain-boundary sliding as the principal deformation mechanism. The electron back-scattered diffraction (EBSD) technique was used to determine the grain orientation as a function of applied strain. The results indicate that some of the grains rotate with cumulative rotation as large as 7 degrees at a strain of 4%.

  10. Deformation effects of droplet fluctuations on dynamics in an Ising ferromagnetic state

    NASA Technical Reports Server (NTRS)

    Nakanishi, Hiizu

    1990-01-01

    Deformation effects of droplet fluctuations on the dynamics in an Ising ferromagnetic state in two dimensions are studied in the case of an order-parameter-nonconserving system by investigating an equation of motion for a domain boundary. Analytic and numerical studies show that the deformation effects on the survival probability of the droplets simply result in changing the time scale or renormalizing a kinetic coefficient.

  11. Lifetime measurements of high-lying short lived states in {sup 69}As

    SciTech Connect

    Matejska-Minda, M.; Bednarczyk, P.; Fornal, B.; Ciemala, M.; Kmiecik, M.; Krzysiek, M.; Maj, A.; Meczynski, W.; Myalski, S.; Styczen, J.; Zieblinski, M.; Angelis, G. de; Huyuk, T.; Michelagnoli, C.; Sahin, E.; Aydin, S.; Farnea, E.; Menegazzo, R.; Recchia, F.; Ur, C. A.; and others

    2012-10-20

    Lifetimes of high-spin states in {sup 69}As have been measured using Doppler shift attenuation technique with the GASP and RFD setup. The determined transition probabilities indicate large deformation associated with some rotational bands in this nucleus.

  12. Charged particle beam scanning using deformed high gradient insulator

    SciTech Connect

    Chen, Yu -Jiuan

    2015-10-06

    Devices and methods are provided to allow rapid deflection of a charged particle beam. The disclosed devices can, for example, be used as part of a hadron therapy system to allow scanning of a target area within a patient's body. The disclosed charged particle beam deflectors include a dielectric wall accelerator (DWA) with a hollow center and a dielectric wall that is substantially parallel to a z-axis that runs through the hollow center. The dielectric wall includes one or more deformed high gradient insulators (HGIs) that are configured to produce an electric field with an component in a direction perpendicular to the z-axis. A control component is also provided to establish the electric field component in the direction perpendicular to the z-axis and to control deflection of a charged particle beam in the direction perpendicular to the z-axis as the charged particle beam travels through the hollow center of the DWA.

  13. Triaxial superdeformed and normal-deformed high-spin band structures in {sup 170}Hf

    SciTech Connect

    Neusser-Neffgen, A.; Huebel, H.; Bringel, P.; Domscheit, J.; Mergel, E.; Nenoff, N.; Singh, A.K.; Hagemann, G.B.; Jensen, D.R.; Bhattacharya, S.; Curien, D.; Dorvaux, O.; Hannachi, F.; Lopez-Martens, A.

    2006-03-15

    The high-spin structure of {sup 170}Hf was investigated using the EUROBALL spectrometer. The previously known level scheme was extended in the low-spin region as well as to higher spins, and several new bands were discovered. In particular, two bands were identified which show the characteristics of triaxial superdeformation. One of these bands is strongly populated, and its excitation energy and spins are established. Configuration assignments are made to the normal-deformed bands based on comparisons of their properties with cranked shell model calculations. The results for the very high spin states provide important input for such calculations.

  14. Analysis of deformation bands in the Aztec Sandstone, Valley of Fire State Park, Nevada

    SciTech Connect

    Hill, R.E. )

    1993-04-01

    This research concerns two types of deformation structures, deformation bands and low-angle slip surfaces, that occur in the Aztec Sandstone in the Valley of Fire State Park, Nevada. Deformation bands were analyzed by mapping and describing over 500 of the structures on a bedding surface of about 560 square meters. Deformation bands are narrow zones of reduced porosity which form resistant ribs in the sandstone. Three sets of deformation bands are present at the study site (type 1,2, and 3). Type 1 and 2 bands are interpreted as coeval and form a conjugate set with a dihedral angle of 90 degrees. These sets are usually composed of multiple bands. A third set is interpreted to be subsidiary to the older set, and intersections angles with the earlier formed sets are approximately 45 degrees. In contrast with the older sets, the third set is nearly always a single band which is sinuous or jagged along its length. All three sets of deformation bands are crosscut and sometimes offset by low-angle slip surfaces. These faults have reverse dip slip displacement and locally have mullions developed. Displacements indicate eastward movement of the hanging wall which is consistent with the inferred movements of major Mesozoic thrust faults in the vicinity. The change of deformation style from deformation bands to low-angle slip surfaces may document a change in the stress regime. Paleostress interpretation of the deformation band geometry indicates the intermediate stress axis is vertical. The low-angle slip surfaces indicate the least compressive stress axis is vertical. This possible change in stress axes may be the result of increasing pore pressure associated with tectonic loading from emplacement of the Muddy Mountain thrust.

  15. Variable-intercept panel model for deformation zoning of a super-high arch dam.

    PubMed

    Shi, Zhongwen; Gu, Chongshi; Qin, Dong

    2016-01-01

    This study determines dam deformation similarity indexes based on an analysis of deformation zoning features and panel data clustering theory, with comprehensive consideration to the actual deformation law of super-high arch dams and the spatial-temporal features of dam deformation. Measurement methods of these indexes are studied. Based on the established deformation similarity criteria, the principle used to determine the number of dam deformation zones is constructed through entropy weight method. This study proposes the deformation zoning method for super-high arch dams and the implementation steps, analyzes the effect of special influencing factors of different dam zones on the deformation, introduces dummy variables that represent the special effect of dam deformation, and establishes a variable-intercept panel model for deformation zoning of super-high arch dams. Based on different patterns of the special effect in the variable-intercept panel model, two panel analysis models were established to monitor fixed and random effects of dam deformation. Hausman test method of model selection and model effectiveness assessment method are discussed. Finally, the effectiveness of established models is verified through a case study.

  16. High-pressure deformation of serpentine + olivine aggregates

    NASA Astrophysics Data System (ADS)

    Hilairet, N.; Ferrand, T. P.; Raterron, P.; Merkel, S.; Guignard, J.; Langrand, C.; Schubnel, A.

    2015-12-01

    Serpentinization is expected to occur when fluids are released from the dehydrating subducting slabs and migrate into shear zones and the mantle wedge peridotites. At shallow depths (15-30km) a few percent volume serpentine can lower the viscosity of peridotites by almost an order of magnitude [1]. However, the deformation mechanisms are not easily extrapolable to deeper contexts. The rheology of a rock with two phases of contrasted mechanical properties is highly non-linear with composition and cannot be modelled from its end-members. Here we investigate the rheology of serpentine + olivine « synthetic » peridotites with varying serpentine content (5 to 50%) at high pressure (2- 3 GPa, ca. 60-90 km depth), using the D-DIA large volume press and synchrotron powder X-ray diffraction and imaging. The results will provide insights on the conditions under which serpentinized peridotites evolve in a regime dominated by the rheology of the strongest phase (olivine) or the weakest phase (antigorite). [1] Escartin et al, Journal of Geophysical Research, 1997

  17. Study of natural rubber crosslinked in the state of uniaxial deformation

    NASA Astrophysics Data System (ADS)

    Dubrović, I.; Klepac, D.; Valić, S.; Žauhar, G.

    2008-06-01

    A natural rubber (NR) film with the thickness of about 1 mm was prepared by removing the liquid phase from NR latex. Two types of NR films crosslinked by γ-irradiation were investigated: (i) samples irradiated in the relaxed state and (ii) samples irradiated in the state of uniaxial deformation. The total irradiation dose varied from 0 kGy (for nonirradiated NR) to 400 kGy and the degree of deformation, defined as λ=l/ l0 ( l0 and l being the lengths of relaxed and uniaxially deformed sample, respectively), was chosen to be λ=1.0 (relaxed state), λ=1.5 and λ=2.0. The amount of sol and gel phase of NR was determined by extracting the sol component in toluene. A significant decrease in the amount of the sol component (from 14.2% to 33.5%, depending on irradiation dose) was observed by increasing the irradiation dose. It has been shown that the application of deformation during the crosslinking leads to the lower crosslink density. Such an effect can be attributed to the loss of the gel component induced mechanically. The electron spin resonance (ESR) spectra of spin probe diffusing in the NR matrix crosslinked under deformation are influenced by both, the local dynamics of the chain segments and their spacious orientation.

  18. From microjoules to megajoules and kilobars to gigabars: Probing matter at extreme states of deformation

    SciTech Connect

    Remington, Bruce A.; Rudd, Robert E.; Wark, Justin S.

    2015-09-15

    Over the past 3 decades, there has been an exponential increase in work done in the newly emerging field of matter at extreme states of deformation and compression. This accelerating progress is due to the confluence of new experimental facilities, experimental techniques, theory, and simulations. Regimes of science hitherto thought out of reach in terrestrial settings are now being accessed routinely. High-pressure macroscopic states of matter are being experimentally studied on high-power lasers and pulsed power facilities, and next-generation light sources are probing the quantum response of matter at the atomic level. Combined, this gives experimental access to the properties and dynamics of matter from femtoseconds to microseconds in time scale and from kilobars to gigabars in pressure. There are a multitude of new regimes of science that are now accessible in laboratory settings. Examples include planetary formation dynamics, asteroid and meteor impact dynamics, space hardware response to hypervelocity dust and debris impacts, nuclear reactor component response to prolonged exposure to radiation damage, advanced research into light weight armor, capsule dynamics in inertial confinement fusion research, and the basic high energy density properties of matter. We review highlights and advances in this rapidly developing area of science and research.

  19. Effects of pairwise versus many-body forces on high-stress plastic deformation

    NASA Astrophysics Data System (ADS)

    Holian, B. L.; Voter, A. F.; Wagner, N. J.; Ravelo, R. J.; Chen, S. P.; Hoover, W. G.; Hoover, C. G.; Hammerberg, J. E.; Dontje, T. D.

    1991-03-01

    We propose a model embedded-atom (many-body) potential and test it against an effective, density-independent, pairwise-additive potential in a variety of nonequilibrium molecular-dynamics simulations of plastic deformation under high stress. Even though both kinds of interactions have nearly the same equilibrium equation of state, the defect energies (i.e., vacancy formation and surface energies) are quite different. As a result, we observe significant qualitative differences in flow behavior between systems characterized by purely pairwise interactions versus higher-order many-body forces.

  20. An Approach for Measuring and Modeling of Plastic Deformation of Metallic Plates during High Velocity Impacts

    SciTech Connect

    O'Toole, Brendan J.; Trabia, Mohamed B.; Roy, Shawoon K.; Somasundarum, Deepak; Jennings, Richard; Matthes, Melissa; Hixson, Robert S.; Becker, Steven; Daykin, Edward P.; Pena, Michael T.; Machorro, Eric A.

    2014-05-29

    During high velocity impact experiments, projectile impact creates extreme pressure waves that results in a significant localized deformation within a short period of time. Experiments under these conditions require sophisticated data acquisition technique to better understand the materials deformation mechanisms. Since these experiments are expensive, it is also beneficial to develop accurate computational models that can predict this kind of deformation in high velocity impact events.

  1. Microscopic description of collective states near the yrast line of nuclei with stable octupole deformation

    NASA Astrophysics Data System (ADS)

    Kvasil, J.; Nazmitdinov, R. G.

    1985-06-01

    Collective states near the yrast line in nuclei with stable octupole deformation are discussed in the framework of the random phase approximation (RPA) based on the cranking model. These vibrational states are characterized by the quantum number of generalized signature (eigenvalue of the operator Sx = PRx-1( π)). In the zero-octupole deformation limit the RPA equations of motion are reduced to the well-known ones characterized by both values of parity and signature, respectively. The connection of the translational and rotational symmetry of the model hamiltonian with the spurious solutions of the RPA equation of motion is discussed. Expressions for the reduced probabilities B(E1), B(E2) and B(E3) are obtained. These expressions confirm the conclusions of phenomenological models for the strong E1 and E3 intraband transitions in nuclei with stable octupole deformation.

  2. Rock Deformation at High Confining Pressure and Temperature.

    DTIC Science & Technology

    debugged, delivered and installed to the contracting agency. Clay specimens of illite, kaolinite and montmorillonite were deformed in tri-axial compression...at 25 and 3000C at a constant confining pressure of 2 kb and a constant strain rate of .0001 sec. The illite and kaolinite are stronger under these...conditions than montmorillonite . Cores from dolomite single crystals were deformed at a confining pressure of 7 kb and temperatures of 300 and 500C

  3. High-load, high-temperature deformation apparatus for synthetic and natural silicate melts

    NASA Astrophysics Data System (ADS)

    Hess, K.-U.; Cordonnier, B.; Lavallée, Y.; Dingwell, D. B.

    2007-07-01

    A unique high-load, high-temperature uniaxial press was developed to measure the rheology of silicate melts and magmatic suspensions at temperature up to 1050°C. This new apparatus is designed to operate at constant stresses (up to 300kN) or constant strain rates (˜10-7 to 100s-1) and further allows us to carry on experiments on samples with high viscosities (˜108 to 1012Pas). The rheological instrument represents an advance in that it accommodates homogeneously heated samples (±2°C) of voluminous sizes (up to 790cm3) which permit the insertion of thermocouples to monitor temperature distribution evolutions during measurements. At last this setup allows for accurate measurements of viscosity of natural multiphase materials at strain rates and temperatures common to natural systems. The apparatus aspires to precisely (1) describe the onset of non-Newtonian behavior and its evolution with increasing strain rate until the point of rupture in the brittle regime, (2) constrain the effect of crystals and bubbles on the viscosity, and (3) record heating dissipated through viscous deformation. Here, we present a series of measurements on NIST standard material SRM 717a to calibrate the instrument. We couple the viscosity determined via Gent's equation with certified viscosity data of the standard material to calibrate this state-of-the-art apparatus. This work shows that we can resolve the viscosity of voluminous melt sample within 0.06 logarithmic unit and furthermore present the detection of minor viscous dissipation for a high-temperature, high strain rate experiment.

  4. Application of distal metaphyseal osteotomy for treatment of high intermetatarsal angle bunion deformities.

    PubMed

    Oloff, L M; Bocko, A P

    1998-01-01

    This is a retrospective study of 10 patients (13 feet) with moderate to severe hallux valgus who underwent a chevron or modified chevron osteotomy with multiple adjunctive soft-tissue releases for surgical treatment. Radiographic and subjective results were evaluated with an average follow-up of 24 months (range, 10-41). Preoperative criteria included an intermetatarsal (IM) angle of greater than 16 degrees (average of 18.4 degrees) and painful hallux valgus deformity. Average preop hallux abductus was 35.4 degrees (range, 25 degrees-48 degrees). The average reduction in the actual IM angle was (-) 5.2 degrees with a relative IM correction of (-) 11.6 degrees. Average postoperative hallux abductus angle was 7.0 degrees (range, 0 degree-22 degrees). Subjectively, all patients were satisfied with their results and stated they would have the procedure again. No complications were noted in this patient population, including, infection, avascular necrosis, hallux varus, and recurrence of deformity. The chevron osteotomy was found to be successful in this population with high intermetatarsal angles when appropriate consideration was given to correction of soft-tissue-deforming forces and contractures.

  5. Deformation processes in orogenic wedges: New methods and application to Northwestern Washington State

    NASA Astrophysics Data System (ADS)

    Thissen, Christopher J.

    Permanent deformation records aspects of how material moves through a tectonic environment. The methods required to measure deformation vary based on rock type, deformation process, and the geological question of interest. In this thesis we develop two new methods for measuring permanent deformation in rocks. The first method uses the autocorrelation function to measure the anisotropy present in two-dimensional photomicrographs and three-dimensional X-ray tomograms of rocks. The method returns very precise estimates for the deformation parameters and works best for materials where the deformation is recorded as a shape change of distinct fabric elements, such as grains. Our method also includes error estimates. Image analysis techniques can focus the method on specific fabric elements, such as quartz grains. The second method develops a statistical technique for measuring the symmetry in a distribution of crystal orientations, called a lattice-preferred orientation (LPO). We show that in many cases the symmetry of the LPO directly constrains the symmetry of the deformation, such axial flattening vs. pure shear vs. simple shear. In addition to quantifying the symmetry, the method uses the full crystal orientation to estimate symmetry rather than pole figures. Pole figure symmetry can often be misleading. This method works best for crystal orientations measured in samples deformed by dislocation creep, but otherwise can be used on any mineral without requiring information about slip systems. In Chapter 4 we show how deformation measurements can be used to inform regional tectonic and orogenic models in the Pacific Northwestern United States. A suite of measurements from the Olympic Mountains shows that uplift and deformation of the range is consistent with an orogenic wedge model driven by subduction of the Juan de Fuca plate, and not northward forearc migration of the Oregon block. The deformation measurements also show that deformation within the Olympic Mountains

  6. The Health Impact of Symptomatic Adult Spinal Deformity: Comparison of Deformity Types to United States Population Norms and Chronic Diseases

    PubMed Central

    Bess, Shay; Line, Breton; Fu, Kai-Ming; McCarthy, Ian; Lafage, Virgine; Schwab, Frank; Shaffrey, Christopher; Ames, Christopher; Akbarnia, Behrooz; Jo, Han; Kelly, Michael; Burton, Douglas; Hart, Robert; Klineberg, Eric; Kebaish, Khaled; Hostin, Richard; Mundis, Gregory; Mummaneni, Praveen; Smith, Justin S.

    2016-01-01

    Study Design. A retrospective analysis of a prospective, multicenter database. Objective. The aim of this study was to evaluate the health impact of symptomatic adult spinal deformity (SASD) by comparing Standard Form Version 2 (SF-36) scores for SASD with United States normative and chronic disease values. Summary of Background Data. Recent data have identified radiographic parameters correlating with poor health-related quality of life for SASD. Disability comparisons between SASD patients and patients with chronic diseases may provide further insight to the disease burden caused by SASD. Methods. Consecutive SASD patients, with no history of spine surgery, were enrolled into a multicenter database and evaluated for type and severity of spinal deformity. Baseline SF-36 physical component summary (PCS) and mental component summary (MCS) values for SASD patients were compared with reported U.S. normative and chronic disease SF-36 scores. SF-36 scores were reported as normative-based scores (NBS) and evaluated for minimally clinical important difference (MCID). Results. Between 2008 and 2011, 497 SASD patients were prospectively enrolled and evaluated. Mean PCS for all SASD was lower than U.S. total population (ASD = 40.9; US = 50; P < 0.05). Generational decline in PCS for SASD patients with no other reported comorbidities was more rapid than U.S. norms (P < 0.05). PCS worsened with lumbar scoliosis and increasing sagittal vertical axis (SVA). PCS scores for patients with isolated thoracic scoliosis were similar to values reported by individuals with chronic back pain (45.5 vs 45.7, respectively; P > 0.05), whereas patients with lumbar scoliosis combined with severe sagittal malalignment (SVA >10 cm) demonstrated worse PCS scores than values reported by patients with limited use of arms and legs (24.7 vs 29.1, respectively; P < 0.05). Conclusions. SASD is a heterogeneous condition that, depending upon the type and severity of the deformity

  7. Deformation and Shear Band Development in an Ultrahigh Carbon Steel During High Strain Rate Deformation

    SciTech Connect

    Lesuer, D R; Syn, C K; Sherby, O D

    2004-07-06

    The mechanical response of a pearlitic UHCS-1.3C steel deformed at approximately 4000 s{sup -1} to large strains ({var_epsilon} = -0.9) has been studied. Failure, at both the macroscopic and the microscopic levels has been evaluated, and the ability of the material to absorb energy in compression has been examined. Failure occurred by the development of a shear band. However before failure, extensive buckling of the carbide plates was observed and the UHCS-1.3C material exhibited significant potential for compressive ductility and energy absorption due to the distributed buckling of these plates. Strain localization during adiabatic shear band development resulted in the formation of austenite. Subsequent cooling produced a divorced-eutectoid transformation with associated deformation, which resulted in a microstructure consisting of 50 to 100 nm sized grains. The stress-strain behavior within the shear band has also been determined. The results are used to critically evaluate the maximum shear stress criterion of shear band development. New criteria for the development of shear bands are developed based on a strain energy concept.

  8. Tidal deformability of neutron and hyperon stars within relativistic mean field equations of state

    NASA Astrophysics Data System (ADS)

    Kumar, Bharat; Biswal, S. K.; Patra, S. K.

    2017-01-01

    We systematically study the tidal deformability for neutron and hyperon stars using relativistic mean field equations of state (EOSs). The tidal effect plays an important role during the early part of the evolution of compact binaries. Although, the deformability associated with the EOSs has a small correction, it gives a clean gravitational wave signature in binary inspiral. These are characterized by various Love numbers kl(l =2 ,3 ,4 ), that depend on the EOS of a star for a given mass and radius. The tidal effect of star could be efficiently measured through an advanced LIGO detector from the final stages of an inspiraling binary neutron star merger.

  9. New Developments in Deformation Experiments at High Pressure

    SciTech Connect

    Durham, W B; Weidner, D J; Karato, S; Wang, Y

    2004-01-09

    Although the importance of rheological properties in controlling the dynamics and evolution of the whole mantle of Earth is well-recognized, experimental studies of rheological properties and deformation-induced microstructures have mostly been limited to low-pressure conditions. This is mainly a result of technical limitations in conducting quantitative rheological experiments under high-pressure conditions. A combination of factors is changing this situation. Increased resolution of composition and configuration of Earth's interior has created a greater demand for well-resolved laboratory measurement of the effects of pressure on the behavior of materials. Higher-strength materials have become readily available for containing high-pressure research devices, and new analytical capabilities--in particular very bright synchrotron X-ray sources--are now readily available to high-pressure researchers. One of the biggest issues in global geodynamics is the style of mantle convection and the nature of chemical differentiation associated with convectional mass transport. Although evidence for deep mantle circulation has recently been found through seismic tomography (e.g., van der Hilst et al. (1997)), complications in convection style have also been noted. They include (1) significant modifications of flow geometry across the mantle transition zone as seen from high resolution tomographic studies (Fukao et al. 1992; Masters et al. 2000; van der Hilst et al. 1991) and (2) complicated patterns of flow in the deep lower mantle ({approx}1500-2500 km), perhaps caused by chemical heterogeneity (Kellogg et al. 1999; van der Hilst and Karason 1999). These studies indicate that while large-scale circulation involving the whole mantle no doubt occurs, significant deviations from simple flow geometry are also present. Two mineral properties have strong influence on convection: (1) density and (2) viscosity (rheology) contrasts. In the past, the effects of density contrast have

  10. Transition in the deformation mode of nanocrystalline tantalum processed by high-pressure torsion

    SciTech Connect

    Ligda, J.P.; Schuster, B.E.; Wei, Q.

    2012-10-11

    We present quasi-static room temperature compression and nanoindentation data for nanocrystalline and ultrafine grained tantalum processed by high-pressure torsion. Because bulk samples possess an inherent gradient in properties, microstructures were characterized using site-specific transmission electron microscopy and synchrotron X-ray diffraction. Nanocrystalline Ta shows appreciable homogeneous plastic deformation in compression; however, specimens with the smallest grain sizes exhibit localized plastic deformation via shear bands. Microstructural changes associated with this transition in deformation mode are discussed.

  11. Deformation and fracture of low alloy steels at high temperature

    SciTech Connect

    Marriott, D.L.; Stubbins, J.F.; Leckie, F.A.; Muddle, B.

    1988-12-01

    This project formed part of the initiative in the AR TD program to characterize high temperature, time-dependent damage processes in low alloy steels, for use in the construction of coal-gasification plant. This project was broadly aimed at adding to the knowledge base for this bainitic form of 2.25Cr 1Mo steel, as it related to time-dependent performance at elevated temperature. Its original intention was to obtain information in specific grades of 2.25Cr 1Mo steel, in particular those containing reduced residual elements and microalloyed modifications, which were being considered as candidate materials at the time. This objective was subsequently modified, in the course of the contract period, to a more generic study of bainitic steel, using the 2.25Cr 1Mo material as a representative of the class. The main thrust of the project was directed initially at the detrimental effect of cyclic loading on creep resistance and manifesting itself in an apparently severe creep-fatigue interaction. Three subtasks were eventually identified. These are: a study of the evolution of microstructural changes in bainitic materials during steady load creep and under constant amplitude cyclic deformation, investigation of the effect of cyclic softening on the fatigue and creep strength of complex geometries, focusing on circumferentially notched bars, and investigation of the influence of environment as a possible cause of observed fatigue/elevated temperature interaction through its effects on crack initiation and propagation, using EDM notched specimens tested in air and vacuum. Results are discussed. 24 refs., 40 figs., 5 tabs.

  12. Deformation and Phase Transformation Processes in Polycrystalline NiTi and NiTiHf High Temperature Shape Memory Alloys

    NASA Technical Reports Server (NTRS)

    Benafan, Othmane

    2012-01-01

    The deformation and transformation mechanisms of polycrystalline Ni49.9Ti50.1 and Ni50.3Ti29.7Hf20 (in at.%) shape memory alloys were investigated by combined experimental and modeling efforts aided by an in situ neutron diffraction technique at stress and temperature. The thermomechanical response of the low temperature martensite, the high temperature austenite phases, and changes between these two states during thermomechanical cycling were probed and reported. In the cubic austenite phase, stress-induced martensite, deformation twinning and slip processes were observed which helped in constructing a deformation map that contained the limits over which each of the identified mechanisms was dominant. Deformation of the monoclinic martensitic phase was also investigated where the microstructural changes (texture, lattice strains, and phase fractions) during room-temperature deformation and subsequent thermal cycling were compared to the bulk macroscopic response. When cycling between these two phases, the evolution of inelastic strains, along with the shape setting procedures were examined and used for the optimization of the transformation properties as a function of deformation levels and temperatures. Finally, this work was extended to the development of multiaxial capabilities at elevated temperatures for the in situ neutron diffraction measurements of shape memory alloys on the VULCAN Diffractometer at Oak Ridge National Laboratory.

  13. Viscoelastic-cycle model of interseismic deformation in the northwestern United States

    USGS Publications Warehouse

    Pollitz, F.F.; McCrory, Patricia; Wilson, Doug; Svarc, Jerry; Puskas, Christine; Smith, Robert B.

    2010-01-01

    We apply a viscoelastic cycle model to a compilation of GPS velocity fields in order to address the kinematics of deformation in the northwestern United States. A viscoelastic cycle model accounts for time-dependent deformation following large crustal earthquakes and is an alternative to block models for explaining the interseismic crustal velocity field. Building on the approach taken in Pollitz et al., we construct a deformation model for the entire western United States-based on combined fault slip and distributed deformation-and focus on the implications for the Mendocino triple junction (MTJ), Cascadia megathrust, and western Washington. We find significant partitioning between strike-slip and dip-slip motion near the MTJ as the tectonic environment shifts from northwest-directed shear along the San Andreas fault system to east-west convergence along the Juan de Fuca Plate. By better accounting for the budget of aseismic and seismic slip along the Cascadia subduction interface in conjunction with an assumed rheology, we revise a previous model of slip for the M~ 9 1700 Cascadia earthquake. In western Washington, we infer slip rates on a number of strike-slip and dip-slip faults that accommodate northward convergence of the Oregon Coast block and northwestward convergence of the Juan de Fuca Plate. Lateral variations in first order mechanical properties (e.g. mantle viscosity, vertically averaged rigidity) explain, to a large extent, crustal strain that cannot be rationalized with cyclic deformation on a laterally homogeneous viscoelastic structure. Our analysis also shows that present crustal deformation measurements, particularly with the addition of the Plate Boundary Observatory, can constrain such lateral variations.

  14. Modeling of high homologous temperature deformation behavior for stress and life-time analyses

    SciTech Connect

    Krempl, E.

    1997-12-31

    Stress and lifetime analyses need realistic and accurate constitutive models for the inelastic deformation behavior of engineering alloys at low and high temperatures. Conventional creep and plasticity models have fundamental difficulties in reproducing high homologous temperature behavior. To improve the modeling capabilities {open_quotes}unified{close_quotes} state variable theories were conceived. They consider all inelastic deformation rate-dependent and do not have separate repositories for creep and plasticity. The viscoplasticity theory based on overstress (VBO), one of the unified theories, is introduced and its properties are delineated. At high homologous temperature where secondary and tertiary creep are observed modeling is primarily accomplished by a static recovery term and a softening isotropic stress. At low temperatures creep is merely a manifestation of rate dependence. The primary creep modeled at low homologous temperature is due to the rate dependence of the flow law. The model is unaltered in the transition from low to high temperature except that the softening of the isotropic stress and the influence of the static recovery term increase with an increase of the temperature.

  15. Stent deformation at the edge of a high pressure balloon.

    PubMed

    Kilic, Ismail Dogu; Foin, Nicolas; Konstantinidis, Nikolaos; Serdoz, Roberta; Caiazzo, Gianluca; Di Mario, Carlo

    2015-12-01

    Focal ultrashort balloons are essential tools for lesion preparation and final stent expansion. However, they may cause a major distortion of the adjacent segments. Here we report a case with a stent deformation emphasizing the importance of utilizing intravascular imaging techniques for optimal interventions.

  16. Structural Deformation of Sm@C88 under High Pressure.

    PubMed

    Cui, Jinxing; Yao, Mingguang; Yang, Hua; Liu, Ziyang; Ma, Fengxian; Li, Quanjun; Liu, Ran; Zou, Bo; Cui, Tian; Liu, Zhenxian; Sundqvist, Bertil; Liu, Bingbing

    2015-08-25

    We have studied the structural transformation of Sm@C88 under pressure up to 18 GPa by infrared spectroscopy combined with theoretical simulations. The infrared-active vibrational modes of Sm@C88 at ambient conditions have been assigned for the first time. Pressure-induced blue and red shifts of the corresponding vibrational modes indicate an anisotropic deformation of the carbon cage upon compression. We propose that the carbon cage changes from ellipsoidal to approximately spherical around 7 GPa. A smaller deformation of the carbon bonds in the area close to the Sm atom in the cage suggests that the trapped Sm atom plays a role in minimizing the compression of the adjacent bonds. Pressure induced a significant reduction of the band gap of the crystal. The HOMO-LUMO gap of the Sm@C88 molecule decreases remarkably at 7 GPa as the carbon cage is deformed. Also, compression enhances intermolecular interactions and causes a widening of the energy bands. Both effects decrease the band gap of the sample. The carbon cage deforms significantly above 7 GPa, from spherical to a peanut-like shape and collapses at 18 GPa.

  17. Structural Deformation of Sm@C88 under High Pressure

    PubMed Central

    Cui, Jinxing; Yao, Mingguang; Yang, Hua; Liu, Ziyang; Ma, Fengxian; Li, Quanjun; Liu, Ran; Zou, Bo; Cui, Tian; Liu, Zhenxian; Sundqvist, Bertil; Liu, Bingbing

    2015-01-01

    We have studied the structural transformation of Sm@C88 under pressure up to 18 GPa by infrared spectroscopy combined with theoretical simulations. The infrared-active vibrational modes of Sm@C88 at ambient conditions have been assigned for the first time. Pressure-induced blue and red shifts of the corresponding vibrational modes indicate an anisotropic deformation of the carbon cage upon compression. We propose that the carbon cage changes from ellipsoidal to approximately spherical around 7 GPa. A smaller deformation of the carbon bonds in the area close to the Sm atom in the cage suggests that the trapped Sm atom plays a role in minimizing the compression of the adjacent bonds. Pressure induced a significant reduction of the band gap of the crystal. The HOMO-LUMO gap of the Sm@C88 molecule decreases remarkably at 7 GPa as the carbon cage is deformed. Also, compression enhances intermolecular interactions and causes a widening of the energy bands. Both effects decrease the band gap of the sample. The carbon cage deforms significantly above 7 GPa, from spherical to a peanut-like shape and collapses at 18 GPa. PMID:26303867

  18. Interrogation of living myocardium in multiple static deformation states with diffusion tensor and diffusion spectrum imaging.

    PubMed

    Lohezic, Maelene; Teh, Irvin; Bollensdorff, Christian; Peyronnet, Rémi; Hales, Patrick W; Grau, Vicente; Kohl, Peter; Schneider, Jürgen E

    2014-08-01

    Diffusion tensor magnetic resonance imaging (MRI) reveals valuable insights into tissue histo-anatomy and microstructure, and has steadily gained traction in the cardiac community. Its wider use in small animal cardiac imaging in vivo has been constrained by its extreme sensitivity to motion, exaggerated by the high heart rates usually seen in rodents. Imaging of the isolated heart eliminates respiratory motion and, if conducted on arrested hearts, cardiac pulsation. This serves as an important intermediate step for basic and translational studies. However, investigating the micro-structural basis of cardiac deformation in the same heart requires observations in different deformation states. Here, we illustrate the imaging of isolated rat hearts in three mechanical states mimicking diastole (cardioplegic arrest), left-ventricular (LV) volume overload (cardioplegic arrest plus LV balloon inflation), and peak systole (lithium-induced contracture). An optimised MRI-compatible Langendorff perfusion setup with the radio-frequency (RF) coil integrated into the wet chamber was developed for use in a 9.4T horizontal bore scanner. Signal-to-noise ratio improved significantly, by 75% compared to a previous design with external RF coil, and stability tests showed no significant changes in mean T1, T2 or LV wall thickness over a 170 min period. In contracture, we observed a significant reduction in mean fractional anisotropy from 0.32 ± 0.02 to 0.28 ± 0.02, as well as a significant rightward shift in helix angles with a decrease in the proportion of left-handed fibres, as referring to the locally prevailing cell orientation in the heart, from 24.9% to 23.3%, and an increase in the proportion of right-handed fibres from 25.5% to 28.4%. LV overload, in contrast, gave rise to a decrease in the proportion of left-handed fibres from 24.9% to 21.4% and an increase in the proportion of right-handed fibres from 25.5% to 26.0%. The modified perfusion and coil setup offers

  19. Interrogation of living myocardium in multiple static deformation states with diffusion tensor and diffusion spectrum imaging

    PubMed Central

    Lohezic, Maelene; Teh, Irvin; Bollensdorff, Christian; Peyronnet, Rémi; Hales, Patrick W.; Grau, Vicente; Kohl, Peter; Schneider, Jürgen E.

    2014-01-01

    Diffusion tensor magnetic resonance imaging (MRI) reveals valuable insights into tissue histo-anatomy and microstructure, and has steadily gained traction in the cardiac community. Its wider use in small animal cardiac imaging in vivo has been constrained by its extreme sensitivity to motion, exaggerated by the high heart rates usually seen in rodents. Imaging of the isolated heart eliminates respiratory motion and, if conducted on arrested hearts, cardiac pulsation. This serves as an important intermediate step for basic and translational studies. However, investigating the micro-structural basis of cardiac deformation in the same heart requires observations in different deformation states. Here, we illustrate the imaging of isolated rat hearts in three mechanical states mimicking diastole (cardioplegic arrest), left-ventricular (LV) volume overload (cardioplegic arrest plus LV balloon inflation), and peak systole (lithium-induced contracture). An optimised MRI-compatible Langendorff perfusion setup with the radio-frequency (RF) coil integrated into the wet chamber was developed for use in a 9.4T horizontal bore scanner. Signal-to-noise ratio improved significantly, by 75% compared to a previous design with external RF coil, and stability tests showed no significant changes in mean T1, T2 or LV wall thickness over a 170 min period. In contracture, we observed a significant reduction in mean fractional anisotropy from 0.32 ± 0.02 to 0.28 ± 0.02, as well as a significant rightward shift in helix angles with a decrease in the proportion of left-handed fibres, as referring to the locally prevailing cell orientation in the heart, from 24.9% to 23.3%, and an increase in the proportion of right-handed fibres from 25.5% to 28.4%. LV overload, in contrast, gave rise to a decrease in the proportion of left-handed fibres from 24.9% to 21.4% and an increase in the proportion of right-handed fibres from 25.5% to 26.0%. The modified perfusion and coil setup offers

  20. Lessons from Dynamic Heds: Diagonite Microstructures Suggest Solid-State Deformation, Annealing and Incipient Differentiation

    NASA Astrophysics Data System (ADS)

    Piazolo, S.; Rushmer, T. A.; Luzin, V.

    2014-12-01

    Diagonite meteorites are commonly thought to represent the deep crust or mantle material of Vesta-like bodies. Here, we present textural analysis by neutron diffraction and microstructural and microchemical data on diagonite Yamato 74013. The meteorite is composed mainly of orthopyroxene with inclusions and interstitial grains of troilite and chromite. A coarse grained orthopyroxene - troilite vein transects the sample. Neutron diffraction data shows a distinct crystallographic preferred orientation (CPO) of the orthopyroxene grains. Such strong CPO is unusual for meteorites such as chondrites and stony meteorites. Detailed electron backscatter diffraction analysis confirms that the origin of the preferred orientation is solid state crystal plastic deformation. All phases in the matrix of the rock show crystal plastic deformation, chromite shows distinct substructures, with inclusions of troilite. Orthopyrxone grains are between 50-120 microns in diameter and exhibit irregular interlocking grain boundaries, subgrain boundaries and continuous crystal lattice bending. Grain boundary morphology suggests post-deformation recrystallization with a dominance of grain boundary migration. Orthopyroxene within the vein have traces of S and show straight grain boundaries to each other. Vein troilite grains are interstitial and reach sizes up to 50 times larger than in the matrix. Our results suggest that deep in Yamato's parent body, orthopyroxene is deformed in a crystal plastic regime and experienced significant post-deformational recrystallization. The irregular distribution of interstitial troilite and chromite suggests that segregation of core material has been incipient retaining significant amounts of metal. One possible conclusion is that within small bodies like Vesta, even though deformation and differentiation were concomitant within a dynamic environment, differentiation was not efficient.

  1. Computer Modelling of Cyclic Deformation of High-Temperature Materials

    DTIC Science & Technology

    1993-06-14

    precision. In this case the aim will be at least to eliminate functional empiricism. Restriction of empiricism to the choice of parameters to be input...deformation of dispersion-hardened materials. In the general case this will be done by a literature search. For specific materials, the micromechanisms...cross-slip and/or climb without the generation of appreciable back-stress. Task 112. Anisotropic dispersoids This task covers the case of dispersoids

  2. Microstructural evolution of Ti-added interstitial free steel in high strain deformation by hot torsion

    NASA Astrophysics Data System (ADS)

    Gholizadeh, R.; Shibata, A.; Terada, D.; Tsuji, N.

    2015-08-01

    The dynamically evolved microstructure under high strain deformation condition does still have many debatable aspects, particularly in the case of easy-recovery metals like bcc-iron. In this research, microstructural evolution in high strain deformation by hot torsion of Ti-added interstitial free (IF) steel was systematically investigated. Torsion specimens were deformed up to an equivalent strain of ∼ 7 at different temperatures (650 °C - 850 °C) and strain rates (0.01 s-1 - 1.0 s-1), i.e., under various values of the Zener-Hollomon (Z) parameter. Immediately after the deformation, samples were water-quenched and microstructures were investigated by electron backscattering diffraction (EBSD) measurements and electron channelling contrast imaging (ECCI). Flow stress-strain curves of the IF steel under various deformation conditions showed typical flow curves of high stacking fault energy metals at low Z values, i.e., a peak stress followed by slight softening. On the other hand, under the high-Z deformation conditions, the specimens showed a larger stress drop after a certain amount of deformation. EBSD-based quantitative analysis was used to study the microstructural transition between high and low Z values. At low Z values, the occurrence of strain induced boundary migration (SIBM) as an initiation of dynamic recrystallization (DRX) was clearly observed. On the other hand, at high Z values, grain subdivision phenomena led to very fine and elongated structures.

  3. Fetal akinesia deformation sequence in a highly developed acardius twin.

    PubMed

    Konstantinidou, A E; Agapitos, E V; Pavlopoulos, P M; Davaris, P S

    1997-10-01

    We report a case of a holoacardius twin with extremely advanced development of the head, face, upper and lower limbs in the absence of all thoracic and upper abdominal viscera and associated with intestinal and anal atresia. The malformed fetus also had craniofacial abnormalities, hydrops, cystic hygroma of the neck, arthrogryposis and pterygia. The monozygous co-twin was found to be normal. The association of acardia with the typical characteristics of the fetal akinesia deformation sequence has not been previously described in the literature.

  4. Bertram Hopkinson's pioneering work and the dislocation mechanics of high rate deformations and mechanically induced detonations.

    PubMed

    Armstrong, Ronald W

    2014-05-13

    Bertram Hopkinson was prescient in writing of the importance of better measuring, albeit better understanding, the nature of high rate deformation of materials in general and, in particular, of the importance of heat in initiating detonation of explosives. This report deals with these subjects in terms of post-Hopkinson crystal dislocation mechanics applied to high rate deformations, including impact tests, Hopkinson pressure bar results, Zerilli-Armstrong-type constitutive relations, shock-induced deformations, isentropic compression experiments, mechanical initiation of explosive crystals and shear banding in metals.

  5. Electro-hydraulic forming of advanced high-strength steels: Deformation and microstructural characterization

    SciTech Connect

    Rohatgi, Aashish; Stephens, Elizabeth V.; Edwards, Danny J.; Smith, Mark T.; Davies, Richard W.

    2012-06-08

    This conference manuscript describes mechanical and microstructural characterization of steel sheets that were deformed via the electro-hydraulic forming technique. The manuscripts shows the importance of the experimental technique developed at PNNL in the sense that the deformation history information enabled by this technique is not obtainable through existing conventional approaches. Additionally, strain-rate effects on texture development during sheet-forming at high-rates are described. Thus, we have demonstrated that it is now possible to correlate deformation history with microstructural development during high-rate forming, a capability that is unique to PNNL.

  6. Deformation twinning of a silver nanocrystal under high pressure. Supplementary materials

    DOE PAGES

    Huang, X. J.; Yang, W. G.; Harder, R.; ...

    2015-10-20

    Within a high-pressure environment, crystal deformation is controlled by complex processes such as dislocation motion, twinning, and phase transitions, which change materials’ microscopic morphology and alter their properties. Likewise, understanding a crystal’s response to external stress provides a unique opportunity for rational tailoring of its functionalities. It is very challenging to track the strain evolution and physical deformation from a single nanoscale crystal under high-pressure stress. Here, we report an in situ three-dimensional mapping of morphology and strain evolutions in a single-crystal silver nanocube within a high-pressure environment using the Bragg Coherent Diffractive Imaging (CDI) method. We also observed amore » continuous lattice distortion, followed by a deformation twining process at a constant pressure. The ability to visualize stress-introduced deformation of nanocrystals with high spatial resolution and prominent strain sensitivity provides an important route for interpreting and engineering novel properties of nanomaterials.« less

  7. Deformation twinning of a silver nanocrystal under high pressure. Supplementary materials

    SciTech Connect

    Huang, X. J.; Yang, W. G.; Harder, R.; Sun, Y.; Lu, M.; Chu, Y. S.; Robinson, I. K.; Mao, H. K.

    2015-10-20

    Within a high-pressure environment, crystal deformation is controlled by complex processes such as dislocation motion, twinning, and phase transitions, which change materials’ microscopic morphology and alter their properties. Likewise, understanding a crystal’s response to external stress provides a unique opportunity for rational tailoring of its functionalities. It is very challenging to track the strain evolution and physical deformation from a single nanoscale crystal under high-pressure stress. Here, we report an in situ three-dimensional mapping of morphology and strain evolutions in a single-crystal silver nanocube within a high-pressure environment using the Bragg Coherent Diffractive Imaging (CDI) method. We also observed a continuous lattice distortion, followed by a deformation twining process at a constant pressure. The ability to visualize stress-introduced deformation of nanocrystals with high spatial resolution and prominent strain sensitivity provides an important route for interpreting and engineering novel properties of nanomaterials.

  8. Texture formation behaviors of Mg-9Al-1Zn alloy during high-temperature compression deformation

    NASA Astrophysics Data System (ADS)

    Park, Minsoo; Okayasu, Kazuto; Fukutomi, Hiroshi; Kim, Kwonhoo

    2016-11-01

    The formation behavior of basal texture during high temperature deformation of AZ91 magnesium alloys in single phase was investigated by plane strain compression deformation. Three kinds of specimens with different initial textures were machined out from a rolled plate having a <0001> texture. The plane strain compression tests were conducted at a temperature of 723 K and a strain of 5.0 × 10-2s-1, with a strain range between -0.4 and -1.0. After deformation, the specimens were immediately quenched in oil. Before deformation, specimen A, {0001} was distributed at the center of pole figure; specimen B shows {0001} was distributed at TD direction; and specimen C, {0001} was distributed at RD direction. Texture evaluation was conducted by Schulz reflection method using nickel-filtered Cu Ka radiation and EBSD. It was found that the main component of texture and the accumulation of pole density vary depending on the deformation condition and the initial texture in all types of specimens. The crystal orientation components in this study were formed by continuous deformation and discontinuous deformation, also when (0001) existed before deformation, an extremely sharp (0001) (compression plane) texture was formed.

  9. High temperature inelastic deformation under uniaxial loading - Theory and experiment

    NASA Technical Reports Server (NTRS)

    Chan, K. S.; Lindholm, U. S.; Bodner, S. R.; Walker, K. P.

    1989-01-01

    The elevated-temperature uniaxial inelastic deformation behavior of an Ni-base alloy, B1900 + Hf, is investigated by performing isothermal tensile, creep, cyclic, stress relaxation, and thermomechanical fatigue tests. The range of strain rates examined is from 10 to the -7th to 100 per sec, while the test temperatures range from 25 to 1093 C. This extensive constitutive data base has been used for evaluating the unified constitutive models of Bodner and Partom (1972) and of Walker (1972) which apply for the small-strain regime. Comparison of test results with independent model predictions indicates good agreement over a broad range of loading conditions, demonstrating the applicability of the unified-constitutive-equation approach for describing the strongly nonlinear and temperature-dependent response of meals under a wide range of deformation and thermal histories. Thus the results give confidence that the unified approach is an effective and efficient approach in which complex history-dependent thermoviscoplastic flow can be represented within a single inelastic strain-rate term.

  10. Motor Evoked Potentials in 43 High Risk Spine Deformities

    PubMed Central

    Biscevic, Mirza; Biscevic, Sejla; Ljuca, Farid; Smrke, Barbara UR; Ozturk, Cagatay; Tiric-Campara, Merita

    2014-01-01

    ABSTRACT Introduction: Correction of pediatric spine deformities is challenging surgical procedures. This fragile group of patients has many risk factors, therefore prevention of most fearing complication-paraplegia is extremely important. Monitoring of transmission of neurophysiological impulses through motor and sensor pathways of spinal cord gives us an insight into cord's function, and predicts postoperative neurological status. Goal: Aim of this work is to present our experiences in monitoring of spinal cord motor function - MEP during surgical corrections of the hardest pediatric spine deformities, pointing on the most dangerous aspects. Material and methods: We analyzed incidence of MEP changes and postoperative neurological status in patients who had major spine correcting surgery in period April ‘11- April ‘14 on our Spine department. Results: Two of 43 patients or 4.6% in our group experienced significant MEP changes during their major spine reconstructive surgeries. We promptly reduced distractive forces, and MEP normalized, and there were no neurological deficit. Neuromonitoring is reliable method which allows us to “catch” early signs of neurological deficits, when they are still in reversible phase. Although IONM cannot provide complete protection of neurological deficit (it reduces risk of paraplegia about 75%), it at least afford a comfort to the surgeon being fear free that his patient is neurologically intact during long lasting procedures. PMID:25568569

  11. Non-rigid registration of medical images based on estimation of deformation states

    NASA Astrophysics Data System (ADS)

    Marami, Bahram; Sirouspour, Shahin; Capson, David W.

    2014-11-01

    A unified framework for automatic non-rigid 3D-3D and 3D-2D registration of medical images with static and dynamic deformations is proposed in this paper. The problem of non-rigid image registration is approached as a classical state estimation problem using a generic deformation model for the soft tissue. The registration technique employs a dynamic linear elastic continuum mechanics model of the tissue deformation, which is discretized using the finite element method. In the proposed method, the registration is achieved through a Kalman-like filtering process, which incorporates information from the deformation model and a vector of observation prediction errors computed from an intensity-based similarity/distance metric between images. With this formulation, single and multiple-modality, 3D-3D and 3D-2D image registration problems can all be treated within the same framework. The performance of the proposed registration technique was evaluated in a number of different registration scenarios. First, 3D magnetic resonance (MR) images of uncompressed and compressed breast tissue were co-registered. 3D MR images of the uncompressed breast tissue were also registered to a sequence of simulated 2D interventional MR images of the compressed breast. Finally, the registration algorithm was employed to dynamically track a target sub-volume inside the breast tissue during the process of the biopsy needle insertion based on registering pre-insertion 3D MR images to a sequence of real-time simulated 2D interventional MR images. Registration results indicate that the proposed method can be effectively employed for the registration of medical images in image-guided procedures, such as breast biopsy in which the tissue undergoes static and dynamic deformations.

  12. Non-rigid registration of medical images based on estimation of deformation states.

    PubMed

    Marami, Bahram; Sirouspour, Shahin; Capson, David W

    2014-11-21

    A unified framework for automatic non-rigid 3D-3D and 3D-2D registration of medical images with static and dynamic deformations is proposed in this paper. The problem of non-rigid image registration is approached as a classical state estimation problem using a generic deformation model for the soft tissue. The registration technique employs a dynamic linear elastic continuum mechanics model of the tissue deformation, which is discretized using the finite element method. In the proposed method, the registration is achieved through a Kalman-like filtering process, which incorporates information from the deformation model and a vector of observation prediction errors computed from an intensity-based similarity/distance metric between images. With this formulation, single and multiple-modality, 3D-3D and 3D-2D image registration problems can all be treated within the same framework. The performance of the proposed registration technique was evaluated in a number of different registration scenarios. First, 3D magnetic resonance (MR) images of uncompressed and compressed breast tissue were co-registered. 3D MR images of the uncompressed breast tissue were also registered to a sequence of simulated 2D interventional MR images of the compressed breast. Finally, the registration algorithm was employed to dynamically track a target sub-volume inside the breast tissue during the process of the biopsy needle insertion based on registering pre-insertion 3D MR images to a sequence of real-time simulated 2D interventional MR images. Registration results indicate that the proposed method can be effectively employed for the registration of medical images in image-guided procedures, such as breast biopsy in which the tissue undergoes static and dynamic deformations.

  13. High temperature deformation behavior of spray-formed and subsequently extruded Al-25Si based alloy

    NASA Astrophysics Data System (ADS)

    Lee, Sin-Woo; Kim, Mok-Soon

    2016-07-01

    The high temperature deformation behavior of spray-formed and subsequently extruded Al-25Si based alloy containing fine Si and ultra-fine intermetallic phases was examined by compressive tests at temperatures between 523 and 743 K and strain rates between 1.0 × 10-3 and 1.0 × 100/s. The true stress-true strain curves obtained from the compressive tests revealed a peak stress at the initial stage of deformation. The peak stress decreased with increasing temperature or decreasing strain rate. A close relationship was observed between the peak stress and the constitutive equation for high temperature deformation. In the deformed specimens, fine equiaxed grains were observed with a mean grain size of 330 590 nm, which was much finer than that measured prior to deformation (1.4 μm). A dislocation structure within the grains was also observed in the deformed specimens, indicating the occurrence of dynamic recrystallization during high temperature deformation of the present alloy. The occurrence of dynamic recrystallization was also supported by the existence of a peak stress in the flow curve.

  14. High-temperature deformation and microstructural analysis for Si3N4-Sc2O3

    NASA Technical Reports Server (NTRS)

    Cheong, Deock-Soo; Sanders, William A.

    1990-01-01

    It was indicated that Si3N4 doped with Sc2O3 may exhibit high temperature mechanical properties superior to Si3N4 systems with various other oxide sintered additives. High temperature deformation of samples was studied by characterizing the microstructures before and after deformation. It was found that elements of the additive, such as Sc and O, exist in small amounts at very thin grain boundary layers and most of them stay in secondary phases at triple and multiple grain boundary junctions. These secondary phases are devitrified as crystalline Sc2Si2O7. Deformation of the samples was dominated by cavitational processes rather than movements of dislocations. Thus the excellent deformation resistance of the samples at high temperature can be attributed to the very small thickness of the grain boundary layers and the crystalline secondary phase.

  15. High resolution transmission electron microscopic in-situ observations of plastic deformation of compressed nanocrystalline gold

    SciTech Connect

    Wang, Guoyong; Lian, Jianshe; Jiang, Qing; Sun, Sheng; Zhang, Tong-Yi

    2014-09-14

    Nanocrystalline (nc) metals possess extremely high strength, while their capability to deform plastically has been debated for decades. Low ductility has hitherto been considered an intrinsic behavior for most nc metals, due to the lack of five independent slip systems actively operating during deformation in each nanograin. Here we report in situ high resolution transmission electron microscopic (HRTEM) observations of deformation process of nc gold under compression, showing the excellent ductility of individual and aggregate nanograins. Compression causes permanent change in the profile of individual nanograins, which is mediated by dislocation slip and grain rotation. The high rate of grain boundary sliding and large extent of widely exited grain rotation may meet the boundary compatibility requirements during plastic deformation. The in situ HRTEM observations suggest that nc gold is not intrinsically brittle under compressive loading.

  16. Proposed criteria for recognizing intrastratal deformation features in marine high resolution seismic reflection profiles

    USGS Publications Warehouse

    O'Leary, D. W.; Laine, E.

    1996-01-01

    Intrastratal deformation of marine strata is ordinarily recorded in high-resolution seismic reflection profiles as acoustically transparent or "chaotic" intervals marked by hyperbolic echoes. Intrastratal deformation is easily confused with buried slump or slide deposits formed initially at the sea floor. Correct identification of intrastratal deformation depends on the presence of a warped continuously reflective layer overlying a chaotic/transparent layer. Decollement is the key criterion for identification in seismic reflection profiles. Other criteria include intrusive structures or faults rooted in a chaotic/transparent layer and thickening and thinning of a chaotic/transparent layer with transitions to reflective intervals.

  17. Laramide thrusting and Tertiary deformation Tierra Caliente, Michoacan and Guerrero States, southwestern Mexico

    SciTech Connect

    Johnson, C.A.; Harrison, C.G.A. ); Lang, H. ); Barros, J.A.; Cabral-Cano, E.

    1990-05-01

    Field investigations and detailed interpretations of Landsat Thematic Mapper images are in progress to improve understanding of regional structure and tectonics of the southernmost extension of the North American cordillera. Two areas have been selected within the Ciudad Altamirano 1:250,000 topographical sheet for geologic mapping and structural interpretation at 1:50,000 scale. The authors results to date require modification of previous ideas concerning the style and timing of deformations, the role and timing of terrane accretion in the overall tectonic history of the region, and the importance of southern Mexico to investigations of the tectonic evolution of the plates in the region. The relative sequence of deformation in the area correlates well with variations in relative motion between North America and plates in the Pacific. Post-Campanian thrusts and generally eastward-verging folds deformed the Mesozoic sequence during the (Laramide equivalent) Hidalgoan orogeny, associated with high-velocity east-west convergence with the Farallon plate that began about 70 Ma. The resulting unconformity was covered by the Tertiary Balsas Formation, a thick sequence of mostly continental clastics. The Tertiary stratigraphy is regionally and sometimes locally variable, but it can be divided into two members. The lower member is relatively volcanic poor and more deformed, and it lies below a regionally significant mid-Tertiary unconformity, which may mark a change to northeast-directed convergence with the Farallon plate sometime prior to 40 Ma. Continued mid-Tertiary deformation in southern Mexico may be related to eastward movement of the Chortis block and the resulting truncation of the Pacific margin of Mexico. The authors also suggest a tentative correlation between the volcaniclastic member of the Lower Cretaceous San Lucas Formation and the protolith of the Roca Verde metamorphics to the east.

  18. Deformed photon-added entangled squeezed vacuum and one-photon states: Entanglement, polarization, and nonclassical properties

    NASA Astrophysics Data System (ADS)

    A, Karimi; M, K. Tavassoly

    2016-04-01

    In this paper, after a brief review on the entangled squeezed states, we produce a new class of the continuous-variable-type entangled states, namely, deformed photon-added entangled squeezed states. These states are obtained via the iterated action of the f-deformed creation operator A = f (n)a † on the entangled squeezed states. In the continuation, by studying the criteria such as the degree of entanglement, quantum polarization as well as sub-Poissonian photon statistics, the two-mode correlation function, one-mode and two-mode squeezing, we investigate the nonclassical behaviors of the introduced states in detail by choosing a particular f-deformation function. It is revealed that the above-mentioned physical properties can be affected and so may be tuned by justifying the excitation number, after choosing a nonlinearity function. Finally, to generate the introduced states, we propose a theoretical scheme using the nonlinear Jaynes-Cummings model.

  19. Minnesota State High School League.

    ERIC Educational Resources Information Center

    Minnesota State Office of the Legislative Auditor, St. Paul. Program Evaluation Div.

    The Minnesota State High School League administers a program of competitive athletic, musical, speech, and dramatics activities at district, region, and state levels. The league is a voluntary association of 433 public and 49 private schools. This monograph reports on a study of the league in regard to two questions: (1) Are policy-making and…

  20. Intruder states and the onset of deformation in the neutron-deficient even-even polonium isotopes

    SciTech Connect

    The ISOLDE Collaboration

    1995-12-01

    Alpha- and beta-decay studies of mass-separated Rn and At nuclei reveal the existence of a low-lying 0{sup +} state in {sup 196,198,200,202}Po. The excited 0{sup +} states are interpreted as proton-pair excitations across the {ital Z}=82 shell gap leading to a deformed state, coexisting with the spherical ground state. It is shown that with decreasing neutron number the deformed configuration intrudes to lower excitation energy, increasingly mixing into the ground state. {copyright} {ital 1995 The American Physical Society.}

  1. Numerical study of the stress state of a deformation twin in magnesium

    SciTech Connect

    Arul Kumar, M.; Kanjarla, A. K.; Niezgoda, S. R.; Lebensohn, R. A.; Tomé, C. N.

    2014-11-26

    Here, we present a numerical study of the distribution of the local stress state associated with deformation twinning in Mg, both inside the twinned domain and in its immediate neighborhood, due to the accommodation of the twinning transformation shear. A full-field elastoviscoplastic formulation based on fast Fourier transformation is modified to include the shear transformation strain associated with deformation twinning. We performed two types of twinning transformation simulations with: (i) the twin completely embedded inside a single crystal and (ii) the twin front terminating at a grain boundary. We show that: (a) the resulting stress distribution is more strongly determined by the shear transformation than by the intragranular character of the twin or the orientation of the neighboring grain; (b) the resolved shear stress on the twin plane along the twin direction is inhomogeneous along the twin–parent interface; and (c) there are substantial differences in the average values of the shear stress in the twin and in the parent grain that contains the twin. We discuss the effect of these local stresses on twin propagation and growth, and the implications of our findings for the modeling of deformation twinning.

  2. Numerical study of the stress state of a deformation twin in magnesium

    SciTech Connect

    Arul Kumar, M.; Kanjarla, A. K.; Niezgoda, S. R.; Lebensohn, R. A.; Tomé, C. N.

    2015-02-01

    We present here a numerical study of the distribution of the local stress state associated with deformation twinning in Mg, both inside the twinned domain and in its immediate neighborhood, due to the accommodation of the twinning transformation shear. A full-field elastoviscoplastic formulation based on fast Fourier transformation is modified to include the shear transformation strain associated with deformation twinning. We have performed two types of twinning transformation simulations with: (i) the twin completely embedded inside a single crystal and (ii) the twin front terminating at a grain boundary. We show that: (a) the resulting stress distribution is more strongly determined by the shear transformation than by the intragranular character of the twin or the orientation of the neighboring grain; (b) the resolved shear stress on the twin plane along the twin direction is inhomogeneous along the twin–parent interface; and (c) there are substantial differences in the average values of the shear stress in the twin and in the parent grain that contains the twin. We discuss the effect of these local stresses on twin propagation and growth, and the implications of our findings for the modeling of deformation twinning.

  3. Numerical study of the stress state of a deformation twin in magnesium

    DOE PAGES

    Arul Kumar, M.; Kanjarla, A. K.; Niezgoda, S. R.; ...

    2014-11-26

    Here, we present a numerical study of the distribution of the local stress state associated with deformation twinning in Mg, both inside the twinned domain and in its immediate neighborhood, due to the accommodation of the twinning transformation shear. A full-field elastoviscoplastic formulation based on fast Fourier transformation is modified to include the shear transformation strain associated with deformation twinning. We performed two types of twinning transformation simulations with: (i) the twin completely embedded inside a single crystal and (ii) the twin front terminating at a grain boundary. We show that: (a) the resulting stress distribution is more strongly determinedmore » by the shear transformation than by the intragranular character of the twin or the orientation of the neighboring grain; (b) the resolved shear stress on the twin plane along the twin direction is inhomogeneous along the twin–parent interface; and (c) there are substantial differences in the average values of the shear stress in the twin and in the parent grain that contains the twin. We discuss the effect of these local stresses on twin propagation and growth, and the implications of our findings for the modeling of deformation twinning.« less

  4. High power solid state lasers

    SciTech Connect

    Weber, H.

    1988-01-01

    These proceedings discuss the following subjects: trends in materials processing with laser radiation; slabs and high power systems; glasses and new crystals; solid state lasers at HOYA Corp.; lamps, resonators and transmission; glasses as active materials for high average power solid state lasers; flashlamp pumped GGG-crystals; alexandrite lasers; designing telescope resonators; mode operation of neodymium: YAG lasers; intracavity frequency doubling with KTP crystal and thermal effects in cylinder lasers.

  5. Intraplate brittle deformation and states of paleostress constrained by fault kinematics in the central German platform

    NASA Astrophysics Data System (ADS)

    Navabpour, Payman; Malz, Alexander; Kley, Jonas; Siegburg, Melanie; Kasch, Norbert; Ustaszewski, Kamil

    2017-01-01

    The structural evolution of Central Europe reflects contrasting tectonic regimes after the Variscan orogeny during Mesozoic - Cenozoic time. The brittle deformation related to each tectonic regime is localized mainly along major fault zones, creating complex fracture patterns and kinematics through time with diverging interpretations on the number and succession of the causing events. By contrast, fracture patterns in less deformed domains often provide a pristine structural inventory. We investigate the brittle deformation of a relatively stable, wide area of the central German platform using fault-slip data to identify the regional stress fields required to satisfy the data. In a non-classical approach, and in order to avoid local stress variations and misinterpretations, the fault-slip data are scaled up throughout the study area into subsets of consistent kinematics and chronology for sedimentary cover and crystalline basement rocks. Direct stress tensor inversion was performed through an iterative refining process, and the computed stress tensors were verified using field-based observations. Criteria on relative tilt geometry and indicators of kinematic change suggest a succession of events, which begins with a post-Triassic normal faulting regime with σ3 axis trending NE-SW. The deformation then follows by strike-slip and thrust faulting regimes with a change of σ1 axis from N-S to NE-SW, supposedly in the Late Cretaceous. Two younger events are characterized by Cenozoic normal and oblique thrust faulting regimes with NW-SE-trending σ3 and σ1 axes, respectively. The fracture patterns of both the cover and basement rocks appear to record the same states of stress.

  6. Structure and mechanical properties of aging Al-Li-Cu-Zr-Sc-Ag alloy after severe plastic deformation by high-pressure torsion

    NASA Astrophysics Data System (ADS)

    Kaigorodova, L. I.; Rasposienko, D. Yu.; Pushin, V. G.; Pilyugin, V. P.; Smirnov, S. V.

    2015-04-01

    The structural and phase transformations have been studied in aging commercial aluminum-lithium alloy Al-1.2 Li-3.2 Cu-0.09 Zr-0.11 Sc-0.4 Ag-0.3 Mg in the as-delivered state and after severe plastic deformation by torsion for 1, 5 and 10 revolutions under a high pressure of 4 GPa. Deformation-induced nanofragmentation and dynamic recrystallization have been found to occur in the alloy. The degree of recrystallization increases with deformation. Nanofragmentation and recrystallization processes are accompanied by the deformation-induced decomposition of solid solution and changes in both the nucleation mechanism of precipitation and the phase composition of the alloy. The influence of a nanostructured nanophase state of the alloy on its mechanical properties (microhardness, plasticity, elastic modulus, and stiffness) is discussed.

  7. Non-proportional/Non-monotonous Deformation Modeling of an Ultra High Strength Automotive Steel Sheet

    NASA Astrophysics Data System (ADS)

    Verma, Rahul K.; Ogihara, Yuki; Kuwabara, Toshihiko; Chung, Kwansoo

    2011-08-01

    In this work, as non-proportional/non-monotonous deformation experiments, two-stage and tension-compression-tension uniaxial tests were performed, respectively, for a cold rolled ultra high strength dual phase steel sheet: DP780. Deformation behaviors under such deformation paths were found different than those of the ultra low carbon single phase steels observed by Verma et al. (Int. J. Plast. 2011, 82-101). To model the newly observed deformation behaviors, the combined type constitutive law previously proposed by Verma et al. (Int. J. Plast. 2011, 82-101) was successfully applied here. Permanent softening observed during reverse loading was properly characterized into the isotropic and kinematic hardening parts of the hardening law using tension-compression-tension test data. The cross effect observed in two-stage tests was also effectively incorporated into the constitutive law.

  8. High-K structure in {sup 250}Fm and the deformed shell gaps at N=152 and Z=100

    SciTech Connect

    Greenlees, P. T.; Ketelhut, S.; Grahn, T.; Jones, P.; Julin, R.; Juutinen, S.; Leino, M.; Nyman, M.; Rahkila, P.; Saren, J.; Scholey, C.; Sorri, J.; Uusitalo, J.; Herzberg, R.-D.; Butler, P. A.; Gray-Jones, C.; Jones, G. D.; Moon, S.; Pakarinen, J.; Rostron, D.

    2008-08-15

    The structure of high-spin and nonyrast states of the transfermium nucleus {sup 250}Fm has been studied in detail. The isomeric nature of a two-quasiparticle excitation has been exploited in order to obtain spectroscopic data of exceptional quality. The data allow the configuration of an isomer first discovered over 30 years ago to be deduced, and provide an unambiguous determination of the location of neutron single-particle states in a very heavy nucleus. A comparison to the known two-quasiparticle structure of {sup 254,252}No confirms the existence of the deformed shell gaps at N=152 and Z=100.

  9. Mixed brittle-plastic deformation behaviour in a slate belt. Examples from the High-Ardenne slate belt (Belgium, Germany)

    NASA Astrophysics Data System (ADS)

    Sintubin, Manuel; van Baelen, Hervé; van Noten, Koen; Muchez, Philippe

    2010-05-01

    again a blocky infill. The detachments reflect the late orogenic destabilisation of the slate belt, again suggesting vein development related to a tectonic inversion (from compression to extension). A kinematic model is developed in which brittle parental cracks are affected by a steady-state solid-state deformation within a creeping shear zone and evolve as plastically deforming fluid-filled cavities. Also this type of quartz veins reflects mixed brittle-plastic deformation behaviour in mid-crustal conditions. Both types of quartz vein demonstrate that fluid-assisted, mixed brittle-plastic deformation in a developing slate belt is strongly related to major changes in the overall stress regime. Both during the tectonic inversion in the earliest and late stages of the Variscan orogeny extensive veining occurred. This is in contrast to the main compression stage of the orogeny, during which vein development seems rather occasional. While the late orogenic vein occurrence can be linked directly to a mid-crustal detachment root of an upper-crustal fault system, the regional aspect of the early orogenic veins remains enigmatic. In both cases a transient strain-rate dependent deepening of the brittle-plastic transition is proposed to explain the formation of the brittle parental cracks. The plastic deformation of the fluid-filled cavities may be related to a recovery of the long-term brittle-plastic transition. The former deepening may thus be related to coseismic loading of the middle crust, while the latter recovery may reflect the postseismic relaxation. In this respect the different types of mixed brittle-plastic vein structures observed in the High-Ardenne slate belt may be seen as a reflection of earthquake-related deformation and fluid redistribution in the middle crust.

  10. High Strain Rate Deformation Modeling of a Polymer Matrix Composite. Part 1; Matrix Constitutive Equations

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Stouffer, Donald C.

    1998-01-01

    Recently applications have exposed polymer matrix composite materials to very high strain rate loading conditions, requiring an ability to understand and predict the material behavior under these extreme conditions. In this first paper of a two part report, background information is presented, along with the constitutive equations which will be used to model the rate dependent nonlinear deformation response of the polymer matrix. Strain rate dependent inelastic constitutive models which were originally developed to model the viscoplastic deformation of metals have been adapted to model the nonlinear viscoelastic deformation of polymers. The modified equations were correlated by analyzing the tensile/ compressive response of both 977-2 toughened epoxy matrix and PEEK thermoplastic matrix over a variety of strain rates. For the cases examined, the modified constitutive equations appear to do an adequate job of modeling the polymer deformation response. A second follow-up paper will describe the implementation of the polymer deformation model into a composite micromechanical model, to allow for the modeling of the nonlinear, rate dependent deformation response of polymer matrix composites.

  11. Microstructures and Mechanical Properties of High-Mn TRIP Steel Based on Warm Deformation of Martensite

    NASA Astrophysics Data System (ADS)

    Guo, Zhikai; Li, Longfei; Yang, Wangyue; Sun, Zuqing

    2015-04-01

    High-Mn TRIP steel with about 5 wt pct Mn was prepared by a thermo-mechanical treatment based on warm deformation of martensite and subsequent short-time annealing in the intercritical region. The microstructural evolution and the mechanical properties of the used steel during such treatment were investigated. The results indicate that during warm deformation of martensite in the intercritical region, the decomposition of martensite was accelerated by warm deformation and the occurrence of dynamic recrystallization of ferrite led to the formation of equiaxed ferrite grains. Meanwhile, the reverse transformation of austenite was accelerated by warm deformation to some extent. During subsequent annealing in the intercritical region, static recrystallization of ferrite led to the increase in the fraction of equiaxed ferrite grains, and the formation of the reversed austenite was accelerated by the addition of the deformation-stored energy, while the stability of the reversed austenite was improved by the accelerated diffusions of C atoms and Mn atoms. As a whole, the mechanical properties of the used steel by the thermo-mechanical treatment based on warm deformation of martensite and subsequent short-time annealing in the intercritical region were comparable to the steels with similar compositions subjected to intercritical annealing for hours after cold rolling of martensite.

  12. High-Resolution Adaptive Optics Scanning Laser Ophthalmoscope with Dual Deformable Mirrors

    SciTech Connect

    Chen, D C; Jones, S M; Silva, D A; Olivier, S S

    2006-08-11

    Adaptive optics scanning laser ophthalmoscope (AO SLO) has demonstrated superior optical quality of non-invasive view of the living retina, but with limited capability of aberration compensation. In this paper, we demonstrate that the use of dual deformable mirrors can effectively compensate large aberrations in the human retina. We used a bimorph mirror to correct large-stroke, low-order aberrations and a MEMS mirror to correct low-stroke, high-order aberration. The measured ocular RMS wavefront error of a test subject was 240 nm without AO compensation. We were able to reduce the RMS wavefront error to 90 nm in clinical settings using one deformable mirror for the phase compensation and further reduced the wavefront error to 48 nm using two deformable mirrors. Compared with that of a single-deformable-mirror SLO system, dual AO SLO offers much improved dynamic range and better correction of the wavefront aberrations. The use of large-stroke deformable mirrors provided the system with the capability of axial sectioning different layers of the retina. We have achieved diffraction-limited in-vivo retinal images of targeted retinal layers such as photoreceptor layer, blood vessel layer and nerve fiber layers with the combined phase compensation of the two deformable mirrors in the AO SLO.

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

    SciTech Connect

    Park, Eun Soo; Kim, Hyong June; Bae, J. C.; Huh, M. Y.

    2013-01-24

    The effect of stress states on the deformation behavior of the Cu54Zr22Ti18Ni6 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. Published by Elsevier B.V.

  14. Texture Development in High-Silicon Iron Sheet Produced by Simple Shear Deformation

    NASA Astrophysics Data System (ADS)

    Kustas, Andrew B.; Sagapuram, Dinakar; Trumble, Kevin P.; Chandrasekar, Srinivasan

    2016-06-01

    Sheet processing of high Si-Fe alloys (up to 6.5 wt pct Si) is demonstrated by application of highly confined shear deformation in cutting-extrusion. This alloy system, of major interest to electromagnetic applications, is characterized by poor workability. By a suitable interactive combination of simple shear, high strain rates, near-adiabatic heating, and large hydrostatic pressure in the deformation zone, flow localization, and cracking inherent to this alloy system are suppressed. This enables creation of sheet and foil forms from bulk ingots, cast or wrought, in a single deformation step, unlike rolling. The sheet is characterized by strong shear textures, described by partial {110} and <111> fibers, and fine-grained microstructures ( 20 µm grain size). The orientation (inclination) of these fibers, with respect to the sheet surface, can be varied over a range of 35 deg through selection of the deformation path. In contrast to rolling textures, the current shear deformation textures are negligibly influenced by recrystallization annealing. A recovery-based continuous recrystallization mechanism is proposed to explain the texture retention. Some general implications for shear-based processing of alloys of limited workability are discussed.

  15. Cryogenic deformation of high temperature superconductive composite structures

    DOEpatents

    Roberts, Peter R.; Michels, William; Bingert, John F.

    2001-01-01

    An improvement in a process of preparing a composite high temperature oxide superconductive wire is provided and involves conducting at least one cross-sectional reduction step in the processing preparation of the wire at sub-ambient temperatures.

  16. On the High Temperature Deformation Behaviour of 2507 Super Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Mishra, M. K.; Balasundar, I.; Rao, A. G.; Kashyap, B. P.; Prabhu, N.

    2017-02-01

    High temperature deformation behaviour of 2507 super duplex stainless steel was investigated by conducting isothermal hot compression tests. The dominant restoration processes in ferrite and austenite phases present in the material were found to be distinct. The possible causes for these differences are discussed. Based on the dynamic materials model, processing map was developed to identify the optimum processing parameters. The microstructural mechanisms operating in the material were identified. A unified strain-compensated constitutive equation was established to describe the high temperature deformation behaviour of the material under the identified processing conditions. Standard statistical parameter such as correlation coefficient has been used to validate the established equation.

  17. High-speed measurements of steel-plate deformations during laser surface processing.

    PubMed

    Jezersek, Matija; Gruden, Valter; Mozina, Janez

    2004-10-04

    In this paper we present a novel approach to monitoring the deformations of a steel plate's surface during various types of laser processing, e.g., engraving, marking, cutting, bending, and welding. The measuring system is based on a laser triangulation principle, where the laser projector generates multiple lines simultaneously. This enables us to measure the shape of the surface with a high sampling rate (80 Hz with our camera) and high accuracy (+/-7 microm). The measurements of steel-plate deformations for plates of different thickness and with different illumination patterns are presented graphically and in an animation.

  18. Can the multianvil apparatus really be used for high-pressure deformation experiments?

    SciTech Connect

    Durham, W.B.; Rubie, D.C.

    1996-04-24

    Past claims of the suitability of the MA-8 multianvil press as a deformation apparatus may have been overstated. On the basis of measurements of final octahedron size and of guide block displacement as a function of time, using the 10/5, 14/8, and 18/11 assemblies (octahedron edge length in mm/truncation edge length in mm) with MgO octahedra and pyrophyllite gasketing, it appears that at run conditions of interest to most researchers there is no appreciable time-dependent creep of gaskets and octahedra. All inelastic deformation occurs at rather low pressures: below about 10 GPa for the 10/5, 7 GPa for the 14/8, and 6 GPa for the 18/11 assemblies, with substantial uncertainties in these pressures. Above these limits all deformation of the pressure medium is elastic. Pressure stepping as a means of increasing the inelastic deformation rate of a sample is probably ineffective. Displacement measured at the guide blocks, previously believed to indicate deformation of the gaskets and octahedron, appears now to be unrelated to creep of these components. The calibrations have not been exhaustive and there is considerable scatter in some of the size measurements, so the above conclusions are not unequivocal. The calibrations do not exclude the possibility of deformation of a few tens of microns after the attainment of high pressure. Efforts to impose permanent shape change to samples at high pressure and temperature simply by relying on long run durations must be viewed with skepticism. There may be possibilities for deformation in the multianvil apparatus if materials of contrasting elastic modulus are used to differentially load a sample during pressure stepping.

  19. Development of high-order segmented MEMS deformable mirrors

    NASA Astrophysics Data System (ADS)

    Helmbrecht, Michael A.; He, Min; Kempf, Carl J.

    2012-03-01

    The areas of biological microscopy, ophthalmic research, and atmospheric turbulence correction require high-order DMs to obtain diffraction-limited images. Iris AO has been developing high-order MEMS DMs to address these requirements. Recent development has resulted in fully functional 489-actuator DMs capable of 9.5 µm stroke. For laser applications, the DMs were modified to make them compatible with high-reflectance dielectric coatings. Experimental results for the 489-actuator DMs with dielectric coatings shows they can be made with superb optical quality λ/93.3 rms (11.4 nm rms) and λ/75.9 rms (20.3 nm rms) for 1064 nm and 1540 nm coatings. Laser testing has demonstrated 300 W/cm2 power handling with off-the-shelf packaging. Power handling of 2800 W/cm2 is projected when incorporating packaging optimized for heat transfer.

  20. The Effect of Anhydrous Ammonia on the Crystalline State Deformation of Nylons 6 and 6,6.

    DTIC Science & Technology

    1981-09-14

    for Public Release; Distribution Unlimited !1 82t 01 11 057 THE EFFECT OF ANHYDROUS AMONIA ON THE CRYSTALLINE STATE DEFORMATION OF NYLONS 6 AND 6,6 by...7 AD-A109 62 MASSACHUSETTS UWIV AMHERST DEPT OF POLYMER SCIENCE -ETC FIG 11/9 THE EFFECT OF ANHYDROUS AMMONIA ON THE CRYSTALLINE STATE DFORN-ETC(U...REPORT NO. 15 "THE EFFECT OF ANHYDROUS AMMONIA ON THE CRYSTALLINE STATE DEFORMATION OF NYLONS 6 AND 6,6" by Tetsuo Kanamoto, Anagnostis E. Zachariades

  1. High Actuator Count MEMS Deformable Mirrors for Space Telescopes

    DTIC Science & Technology

    2010-06-07

    Astronomy – Direct Planet Detection • High Contrast Imaging – Astronomy/Reconnaissance • Correction of surface figure errors in Light weight primary mirrors...NASA’s TPF Coronagraphic Imaging Observatory EPIC PECO Extrasolar Planetary Imaging Coronagraph Pupil-mapping Exoplanet Coronagraphic Observer Why

  2. Nanoscale deformation analysis with high-resolution transmission electron microscopy and digital image correlation

    DOE PAGES

    Wang, Xueju; Pan, Zhipeng; Fan, Feifei; ...

    2015-09-10

    We present an application of the digital image correlation (DIC) method to high-resolution transmission electron microscopy (HRTEM) images for nanoscale deformation analysis. The combination of DIC and HRTEM offers both the ultrahigh spatial resolution and high displacement detection sensitivity that are not possible with other microscope-based DIC techniques. We demonstrate the accuracy and utility of the HRTEM-DIC technique through displacement and strain analysis on amorphous silicon. Two types of error sources resulting from the transmission electron microscopy (TEM) image noise and electromagnetic-lens distortions are quantitatively investigated via rigid-body translation experiments. The local and global DIC approaches are applied for themore » analysis of diffusion- and reaction-induced deformation fields in electrochemically lithiated amorphous silicon. As a result, the DIC technique coupled with HRTEM provides a new avenue for the deformation analysis of materials at the nanometer length scales.« less

  3. Nanoscale deformation analysis with high-resolution transmission electron microscopy and digital image correlation

    SciTech Connect

    Wang, Xueju; Pan, Zhipeng; Fan, Feifei; Wang, Jiangwei; Liu, Yang; Mao, Scott X.; Zhu, Ting; Xia, Shuman

    2015-09-10

    We present an application of the digital image correlation (DIC) method to high-resolution transmission electron microscopy (HRTEM) images for nanoscale deformation analysis. The combination of DIC and HRTEM offers both the ultrahigh spatial resolution and high displacement detection sensitivity that are not possible with other microscope-based DIC techniques. We demonstrate the accuracy and utility of the HRTEM-DIC technique through displacement and strain analysis on amorphous silicon. Two types of error sources resulting from the transmission electron microscopy (TEM) image noise and electromagnetic-lens distortions are quantitatively investigated via rigid-body translation experiments. The local and global DIC approaches are applied for the analysis of diffusion- and reaction-induced deformation fields in electrochemically lithiated amorphous silicon. As a result, the DIC technique coupled with HRTEM provides a new avenue for the deformation analysis of materials at the nanometer length scales.

  4. Concept and modeling analysis of a high fidelity multimode deformable mirror.

    PubMed

    Zhou, Chao; Li, Yun; Wang, Anding; Xing, Tingwen

    2015-06-10

    Conventional deformable mirrors (DM) cannot meet the requirement of aberration controlling for advanced lithography tools. This paper illustrates an approach using the property that deformation of a thin plate is similar to optical modes to realize a high fidelity multimode deformable mirror whose deformation has characteristics of optical aberration modes. The way to arrange actuators is also examined. In this paper, a 36-actuator deformable mirror is taken as an example to generate low-order Zernike modes. The result shows that this DM generates the fourth fringe Zernike mode (Z4) defocus, and primary aberration Z5-Z8 with an error less than 0.5%, generates the fifth-order aberration Z10-Z14, and generates the seventh-order aberration Z17-Z20 with an error less than 1.1%. The high fidelity replication of the Zernike mode indicates that the DM satisfies the demand of controlling aberrations corresponding to the first 20 Zernike modes in an advanced lithography tool.

  5. High-resolution adaptive optics scanning laser ophthalmoscope with dual deformable mirrors for large aberration correction

    SciTech Connect

    Chen, D; Jones, S M; Silva, D A; Olivier, S S

    2007-01-25

    Scanning laser ophthalmoscopes with adaptive optics (AOSLO) have been shown previously to provide a noninvasive, cellular-scale view of the living human retina. However, the clinical utility of these systems has been limited by the available deformable mirror technology. In this paper, we demonstrate that the use of dual deformable mirrors can effectively compensate large aberrations in the human retina, making the AOSLO system a viable, non-invasive, high-resolution imaging tool for clinical diagnostics. We used a bimorph deformable mirror to correct low-order aberrations with relatively large amplitudes. The bimorph mirror is manufactured by Aoptix, Inc. with 37 elements and 18 {micro}m stroke in a 10 mm aperture. We used a MEMS deformable mirror to correct high-order aberrations with lower amplitudes. The MEMS mirror is manufactured by Boston Micromachine, Inc with 144 elements and 1.5 {micro}m stroke in a 3 mm aperture. We have achieved near diffraction-limited retina images using the dual deformable mirrors to correct large aberrations up to {+-} 3D of defocus and {+-} 3D of cylindrical aberrations with test subjects. This increases the range of spectacle corrections by the AO systems by a factor of 10, which is crucial for use in the clinical environment. This ability for large phase compensation can eliminate accurate refractive error fitting for the patients, which greatly improves the system ease of use and efficiency in the clinical environment.

  6. State injection, lattice surgery, and dense packing of the deformation-based surface code

    NASA Astrophysics Data System (ADS)

    Nagayama, Shota; Satoh, Takahiko; Van Meter, Rodney

    2017-01-01

    Resource consumption of the conventional surface code is expensive, in part due to the need to separate the defects that create the logical qubit far apart on the physical qubit lattice. We propose that instantiating the deformation-based surface code using superstabilizers will make it possible to detect short error chains connecting the superstabilizers, allowing us to place logical qubits close together. Additionally, we demonstrate the process of conversion from the defect-based surface code, which works as arbitrary state injection, and a lattice-surgery-like controlled not (cnot) gate implementation that requires fewer physical qubits than the braiding cnot gate. Finally, we propose a placement design for the deformation-based surface code and analyze its resource consumption; large-scale quantum computation requires 25/d2+170 d +289 4 physical qubits per logical qubit, where d is the code distance of the standard surface code, whereas the planar code requires 16 d2-16 d +4 physical qubits per logical qubit, for a reduction of about 50%.

  7. Butterflies' wings deformations using high speed digital holographic interferometry

    NASA Astrophysics Data System (ADS)

    Mendoza Santoyo, Fernando; Aguayo, Daniel D.; de La Torre-Ibarra, Manuel H.; Salas-Araiza, Manuel D.

    2011-08-01

    A variety of efforts in different scientific disciplines have tried to mimic the insect's in-flight complex system. The gained knowledge has been applied to improve the performance of different flying artifacts. In this research report it is presented a displacement measurement on butterflies' wings using the optical noninvasive Digital Holographic Interferometry technique with out of plane sensitivity, using a high power cw laser and a high speed CMOS camera to record the unrepeatable displacement movements on these organic tissues. A series of digital holographic interferograms were recorded and the experimental results for several butterflies during flapping events. The relative unwrapped phase maps micro-displacements over the whole wing surface are shown in a wire-mesh representation. The difference between flying modes is remarkably depicted among them.

  8. The Deformability of a High Performance Concrete (HPC)

    NASA Astrophysics Data System (ADS)

    Benamara, Dalila; Mezghiche, Bouzidi; Zohra, Mechrouh Fatma

    The current tendency in the world is to find new materials at lower cost which can guarantee better performances during their incorporations in the concretes. Our study lies within the scope of the valorization of local materials. Among these materials we find the high performance concrete, which has become the object of the several researchers for a few years. This study consists the development and the mechanical and elastic properties of a concrete with high performances (HPC) starting from materials existing on the Algerian market. Three mineral additions: limestone, the sand of dune and the waste of polishing of tiling are incorporated a cement with various contents (5%, 10%, 15% and 20%). instead of the fume of silica or fly-ashes.

  9. Friction properties and deformation mechanisms of halite(-mica) gouges from low to high sliding velocities

    NASA Astrophysics Data System (ADS)

    Buijze, Loes; Niemeijer, André R.; Han, Raehee; Shimamoto, Toshihiko; Spiers, Christopher J.

    2017-01-01

    The evolution of friction as a function of slip rate is important in understanding earthquake nucleation and propagation. Many laboratory experiments investigating friction of fault rocks are either conducted in the low velocity regime (10-8-10-4 ms-1) or in the high velocity regime (0.01-1 m s-1). Here, we report on the evolution of friction and corresponding operating deformation mechanisms in analog gouges deformed from low to high slip rates, bridging the gap between these low and high velocity regimes. We used halite and halite-muscovite gouges to simulate processes, governing friction, active in upper crustal quartzitic fault rocks, at conditions accessible in the laboratory. The gouges were deformed over a 7 orders of magnitude range of slip rate (10-7-1 m s-1) using a low-to-high velocity rotary shear apparatus, using a normal stress of 5 MPa and room-dry humidity. Microstructural analysis was conducted to study the deformation mechanisms. Four frictional regimes as a function of slip rate could be recognized from the mechanical data, showing a transitional regime and stable sliding (10-7-10-6 m s-1), unstable sliding and weakening (10-6-10-3 m s-1), hardening (10-2-10-1 m s-1) and strong weakening (10-1-1 m s-1). Each of the four regimes can be associated with a distinct microstructure, reflecting a transition from mainly brittle deformation accompanied by pressure solution healing to temperature activated deformation mechanisms. Additionally, the frictional response of a sliding gouge to a sudden acceleration of slip rate to seismic velocities was investigated. These showed an initial strengthening, the amount of which depended on the friction level at which the step was made, followed by strong slip weakening.

  10. Bulk and particle strain analysis in high-temperature deformation experiments

    NASA Astrophysics Data System (ADS)

    Quane, Steven L.; Russell, J. K.

    2006-06-01

    Experimental data alone are not sufficient to describe the rheology of deformed geomaterials. To fully characterize a material's rheological properties, independent verification of deformation mechanisms is required. Here, we use standard image analysis techniques to semi-quantify the physical changes in experimentally deformed cores of soda-lime silica glass beads and rhyolite ash previously described by Quane and Russell [Quane, S.L., Russell, J.K., 2005a. Welding: insights from high-temperature analogue experiments. J. Volcanol. Geotherm. Res. 142, 67-87]. The properties we measure by image analysis include porosity, radial bulging and particle elongation. The image analysis measurements combined with digital output from the experiments allow us to determine the amount of total axial and radial strain accumulated by the bulk sample ( ɛb) and by individual particles ( ɛp). We demonstrate that these metrics of strain are nearly equal to the one-dimensional strain recorded by the deformation apparatus ( ɛm) and sample shortening ( ɛs), confirming that all strain introduced by the deformation apparatus is being transferred into both the bulk sample and individual particles. We also show that ɛb is manifest as two discrete components: axial ( ɛa) and radial ( ɛr) strain. We use these independent components of strain accumulation to show that, despite having nearly identical strain-time and stress-strain deformation paths, glass bead cores and rhyolite ash cores have strikingly different mechanisms of strain accumulation. In the higher porosity rhyolite ash cores, axial strain dominates, implying that, under the conditions present, natural glassy particulate geomaterials deform almost entirely by porosity loss.

  11. Hydrostatic Stress Effects Incorporated Into the Analysis of the High-Strain-Rate Deformation of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Roberts, Gary D.

    2003-01-01

    Procedures for modeling the effect of high strain rate on composite materials are needed for designing reliable composite engine cases that are lighter than the metal cases in current use. The types of polymer matrix composites that are likely to be used in such an application have a deformation response that is nonlinear and that varies with strain rate. The nonlinearity and strain rate dependence of the composite response is primarily due to the matrix constituent. Therefore, in developing material models to be used in the design of impact-resistant composite engine cases, the deformation of the polymer matrix must be correctly analyzed. However, unlike in metals, the nonlinear response of polymers depends on the hydrostatic stresses, which must be accounted for within an analytical model. An experimental program has been carried out through a university grant with the Ohio State University to obtain tensile and shear deformation data for a representative polymer for strain rates ranging from quasi-static to high rates of several hundred per second. This information has been used at the NASA Glenn Research Center to develop, characterize, and correlate a material model in which the strain rate dependence and nonlinearity (including hydrostatic stress effects) of the polymer are correctly analyzed. To obtain the material data, Glenn s researchers designed and fabricated test specimens of a representative toughened epoxy resin. Quasi-static tests at low strain rates and split Hopkinson bar tests at high strain rates were then conducted at the Ohio State University. The experimental data confirmed the strong effects of strain rate on both the tensile and shear deformation of the polymer. For the analytical model, Glenn researchers modified state variable constitutive equations previously used for the viscoplastic analysis of metals to allow for the analysis of the nonlinear, strain-rate-dependent polymer deformation. Specifically, we accounted for the effects of

  12. Self-localized states for electron transfer in nonlocal continuum deformable media

    NASA Astrophysics Data System (ADS)

    Cisneros-Ake, Luis A.

    2016-08-01

    We consider the problem of electron transport in a deformable continuum medium subjected to an external harmonic substrate potential. We then consider the quasi-stationary state of the full problem to find a Gross-Pitaevskii type equation with a nonlocal external potential, which is solved by variational and numerical means (considered as the exact solution) to find the parameter conditions for the existence of self-localized solutions. The variational approach predicts a threshold on the on-site or nonlocality parameter where localized solutions cease to exist from the Non-Linear Schrödinger soliton limit. A numerical continuation of stationary state solutions in the corresponding discrete system is used to confirm the prediction of the turning value in the on-site term. We finally study the full stationary state and make use of an approximation, proposed by Briedis et al. [17], for the nonlocal term, corresponding to strong nonlocalities, to find analytic expressions for self-localized states in terms of the series solutions of a nonlinear modified Bessel equation.

  13. High-rate deformation of nanocrystalline iron and copper

    NASA Astrophysics Data System (ADS)

    Sinani, A. B.; Shpeizman, V. V.; Vlasov, A. S.; Zil'berbrand, E. L.; Kozachuk, A. I.

    2016-11-01

    Stress-strain curves are recorded during a high-speed impact and slow loading for nanocrystalline and coarse-grained iron and copper. The strain-rate sensitivity is determined as a function of the grain size and the strain. It is shown that the well-known difference between the variations of the strain-rate sensitivity of the yield strength with the grain size in fcc and bcc metals can be extended to other strain dependences: the strain-rate sensitivity of flow stresses in iron decreases with increasing strain, and that in copper increases. This difference also manifests itself in different slopes of the dependence of the strain-rate sensitivity on the grain size when the strain changes.

  14. Nonlinear deformation of skeletal muscles in a passive state and in isotonic contraction

    NASA Astrophysics Data System (ADS)

    Shil'ko, S. V.; Chernous, D. A.; Pleskachevskii, Yu. M.

    2012-07-01

    A procedure for a two-level modeling of deformation of skeletal muscles is offered. Based on a phenomenological model of an individual muscle fiber, consisting of a viscous, a contractive, and two nonlinearly elastic elements (the first level), various means for describing a skeletal muscle as a whole (the second, macroscopic level) are considered. A method for identification of a muscle model by utilizing experimental elongation diagrams in a passive state and in isotonic contraction is put forward. The results of a biomechanical analysis are compared with known experimental data for the isotonic and isometric activation regimes of tailor's muscle of a frog. It is established that preferable is the description of a muscle that takes into account the different lengths of muscle fibers and their twist.

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

    NASA Technical Reports Server (NTRS)

    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.

  16. Extrinsic and intrinsic fracture behavior of high pressure torsion deformed nickel

    PubMed Central

    Rathmayr, Georg B.; Pippan, Reinhard

    2012-01-01

    Nickel discs (>99.5 wt.%) were deformed by high pressure torsion (HPT) at different temperatures (−196 °C, 25 °C, 200 °C, and 400 °C) until saturation was reached. The strength and fracture behavior of microdefect-free samples and samples with inclusions were investigated using micro and macro tensile tests, respectively. The fracture behavior is not sensitive to the HPT deformation temperature but differs significantly in the two types of sample. The ultimate tensile strength is not affected by inclusions or grain texture. PMID:23471511

  17. Deformation behavior of titanate nanotubes subjected to high pressure

    NASA Astrophysics Data System (ADS)

    Ojeda-Galván, H. J.; Rodríguez, A. G.; Santos-López, I. A.; Mendoza-Cruz, R.; Yacamán, M. J.; Handy, B. E.

    2017-01-01

    Nano-sized titania (anatase) and sodium and potassium titanate nanotubes were studied via in situ Raman spectroscopy at hydrostatic pressures up to 6 GPa. Analysis by scanning electron microscopy shows a uniform dispersion of sodium and potassium cations in the nanotubes. The effect of the pressure was observed by significant shifts in the Raman band structure of nano-sized anatase crystals and nanotube titanate. In nano-particulate anatase, the phonon frequencies (143, 395, 517, and 639 cm-1) increase linearly with pressure. In contrast, the upward frequency shifts in the sodium titanate nanotubes (NaTNT) and potassium-modified nanotubes (NaTNT+K) occur in a stepwise fashion. These stepwise changes occur in the nanotube samples between 2 and 4 GPa (ambient pressure phonon bands in NaTNT at 274, 444, 650, and 906 cm-1) and between 4.5 and 5.5 GPa, (phonons 273 cm-1 and 436 cm-1 in NaTNT+K at an ambient pressure). Post-pressure high-resolution transmission electron microscopy analysis shows evidence of nanotube distortions and a 5% contraction in the interlaminar spacing of both NaTNT and NaTNT+K.

  18. High pressure and temperature deformation experiments on San Carlos olivine and implications for upper mantle anisotropy

    NASA Astrophysics Data System (ADS)

    Shekhar, Sushant; Frost, Daniel J.; Walte, Nicolas; Miyajima, Nobuyoshi; Heidelbach, Florian

    2010-05-01

    Crystallographic preferred orientation developed in olivine due to shearing in the mantle is thought to be the prominent reason behind seismic anisotropy in the upper mantle. Seismic anisotropy in upper mantle can be observed up to a depth of 350 km with a marked drop in the strength of anisotropy seen around 250 km. Studies on natural rock samples from the mantle and deformation experiments performed on olivine have revealed that olivine deforms mainly through dislocation creep with Burgers vectors parallel to the [100] crystallographic axis under low pressure conditions (up to 3 GPa). Under similar pressures, evidence of [001] slip has been reported due to the presence of water. In order to understand the deformation mechanism in olivine at pressures greater than 3 GPa, we have performed experiments using the deformation DIA multi-anvil apparatus. The DIA consist of 6 square faceted anvils that compress a cubic high-pressure assembly. The deformation DIA possesses two vertically acting opposing inner rams, which can be operated independently of the main compressive force to deform the sample assembly. The experimental setup consists of a hot-pressed sample of polycrystalline dry San Carlos olivine 0.2 mm cut from a 1.2 mm diameter core at 45° . This slice is sandwiched between alumina pistons also cut at 45° in simple shear geometry. Experiments have been performed at 3, 5 and 8 GPa at a deformation anvil strain rate of 1.0x10-4 s-1and temperatures between 1200-1400° C. Deformed samples were cut normal to the shear plane and parallel to the shear direction. Then the sample was polished and analyzed using electron back scattered diffraction (EBSD) to identify the crystallographic preferred orientation (CPO). The fabric that developed in olivine deformed at 3 GPa mainly resulted from the [100] slip on the (010) plane. Samples deformed at 5 GPa showed both [100] and [001] slip. On the other hand, samples deformed at 8 GPa and 1200° C, show deformation mainly

  19. The effect of aspect ratio on the compressive high rate deformation of three metallic alloys

    NASA Astrophysics Data System (ADS)

    Walley, S. M.; Radford, D. D.; Chapman, D. J.

    2006-08-01

    Metallic cylinders of rolled homogeneous armour (RHA) steel, Ti6Al4V, and FNC tungsten alloy of four different length l to diameter d ratios (dimensions in mm): 8/4, 4/8, 10/8, 8/10) were deformed at high rates of deformation using a direct impact Hopkinson pressure bar. Highspeed photographic sequences of the deformation were taken using a Hadland Imacon 790 imageconverter camera working at either 1 or 2 x 104 frames/s. It was found that titanium alloy cylinders of all four aspect ratios shear-banded and fractured, but that cylinders made from RHA steel and FNC tungsten behaved in a ductile manner when l/d < 1 but in a brittle manner when l/d > 1. We conclude that adiabatic shear banding is not just an inherent material property but that in some materials size effects/geometry can trigger this phenomenon.

  20. An Immersed-Boundary method for deformable bodies at high Reynolds numbers

    NASA Astrophysics Data System (ADS)

    de Marinis, Dario; Krishnan, Sreenath; de Tullio, Marco Donato; Napolitano, Michele; Pascazio, Giuseppe; Iaccarino, Gianluca

    2015-11-01

    With the aim of accurately simulate the flow-field through gas turbine blades a numerical approach is presented, that couples a massively parallel, finite volume Unsteady Reynolds Averaged Navier-Stokes Equations solver with an efficient structural solver describing the dynamics of deformable bodies, using an iterative coupled approach. The numerical strategy is based on a suitable version of the immersed boundary (IB) technique, which is able to handle rigid and deformable complex geometries in turbulent flows. The structures are discretized by a surface mesh of three-node triangular elements and modeled by means of a finite element method. The solution of the fluid-structure-interaction (FSI) problem produces detailed information of the flow patterns through realistic geometries subject to small deformations at high Reynolds and Mach numbers. Via Orabona 4 - 70125 - Bari, Italy.

  1. Role of deformation twins in static recrystallization kinetics of high-purity alpha titanium

    NASA Astrophysics Data System (ADS)

    Won, Jong Woo; Lee, Taekyung; Hong, Seong-Gu; Lee, Yongmoon; Lee, Jeong Hun; Lee, Chong Soo

    2016-11-01

    The importance of deformation twins in static recrystallization kinetics of high-purity alpha titanium was investigated by carrying out thermal annealing tests of deformed materials in combination with electron-backscatterdiffraction- based microstructural analysis. Prior to thermal annealing, the material was compressed to a true strain of 0.22 along three directions to introduce different twinning characteristics. Our results showed that deformation twins substantially promoted the static recrystallization process by deepening the microstructural inhomogeneity induced by the formation of twin boundaries and twinning-induced crystallographic lattice reorientation. Twin morphology was also observed to be important because it influenced the extent of microstructural inhomogeneity. Intersecting twin morphology, caused by the activation of multiple twin variants, was more effective than parallel twin morphology, caused by the activation of a single twin variant (or a twin variant pair), because it gave rise to more twin boundaries, more twin boundary junctions (intersections, triple junctions, etc.), and greater in-grain crystallographic orientation spread.

  2. High Strain Rate Deformation Modeling of a Polymer Matrix Composite. Part 2; Composite Micromechanical Model

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Stouffer, Donald C.

    1998-01-01

    Recently applications have exposed polymer matrix composite materials to very high strain rate loading conditions, requiring an ability to understand and predict the material behavior under these extreme conditions. In this second paper of a two part report, a three-dimensional composite micromechanical model is described which allows for the analysis of the rate dependent, nonlinear deformation response of a polymer matrix composite. Strain rate dependent inelastic constitutive equations utilized to model the deformation response of a polymer are implemented within the micromechanics method. The deformation response of two representative laminated carbon fiber reinforced composite materials with varying fiber orientation has been predicted using the described technique. The predicted results compare favorably to both experimental values and the response predicted by the Generalized Method of Cells, a well-established micromechanics analysis method.

  3. Temperature effects on deformation and serration behavior of high-entropy alloys (HEAs)

    SciTech Connect

    Antonaglia, J.; Xie, X.; Tang, Z.; Tsai, C. -W.; Qiao, J. W.; Zhang, Y.; Laktionova, M. O.; Tabachnikova, E. D.; Yeh, J. W.; Senkov, O. N.; Gao, M. C.; Uhl, J. T.; Liaw, P. K.; Dahmen, K. A.

    2014-09-16

    Many materials are known to deform under shear in an intermittent way with slip avalanches detected as acoustic emission and serrations in the stress–strain curves. Similar serrations have recently been observed in a new class of materials, called high-entropy alloys (HEAs). Here, we discuss the serration behaviors of several HEAs from cryogenic to elevated temperatures. The experimental results of slow compression and tension tests are compared with the predictions of a slip-avalanche model for the deformation of a broad range of solids. The results shed light on the deformation processes in HEAs. Temperature effects on the distributions of stress drops and the decrease of the cutoff (i.e., of the largest observed slip size) for increasing temperature qualitatively agree with the model predictions. As a result, the model is used to quantify the serration characteristics of HEAs, and pertinent implications are discussed.

  4. Temperature effects on deformation and serration behavior of high-entropy alloys (HEAs)

    DOE PAGES

    Antonaglia, J.; Xie, X.; Tang, Z.; ...

    2014-09-16

    Many materials are known to deform under shear in an intermittent way with slip avalanches detected as acoustic emission and serrations in the stress–strain curves. Similar serrations have recently been observed in a new class of materials, called high-entropy alloys (HEAs). Here, we discuss the serration behaviors of several HEAs from cryogenic to elevated temperatures. The experimental results of slow compression and tension tests are compared with the predictions of a slip-avalanche model for the deformation of a broad range of solids. The results shed light on the deformation processes in HEAs. Temperature effects on the distributions of stress dropsmore » and the decrease of the cutoff (i.e., of the largest observed slip size) for increasing temperature qualitatively agree with the model predictions. As a result, the model is used to quantify the serration characteristics of HEAs, and pertinent implications are discussed.« less

  5. High-pressure creep of serpentine, interseismic deformation, and initiation of subduction.

    PubMed

    Hilairet, Nadege; Reynard, Bruno; Wang, Yanbin; Daniel, Isabelle; Merkel, Sebastien; Nishiyama, Norimasa; Petitgirard, Sylvain

    2007-12-21

    The supposed low viscosity of serpentine may strongly influence subduction-zone dynamics at all time scales, but until now its role could not be quantified because measurements relevant to intermediate-depth settings were lacking. Deformation experiments on the serpentine antigorite at high pressures and temperatures (1 to 4 gigapascals, 200 degrees to 500 degrees C) showed that the viscosity of serpentine is much lower than that of the major mantle-forming minerals. Regardless of the temperature, low-viscosity serpentinized mantle at the slab surface can localize deformation, impede stress buildup, and limit the downdip propagation of large earthquakes at subduction zones. Antigorite enables viscous relaxation with characteristic times comparable to those of long-term postseismic deformations after large earthquakes and slow earthquakes. Antigorite viscosity is sufficiently low to make serpentinized faults in the oceanic lithosphere a site for subduction initiation.

  6. High resolution transmission electron microscope observation of zero-strain deformation twinning mechanisms in Ag.

    PubMed

    Liu, L; Wang, J; Gong, S K; Mao, S X

    2011-04-29

    We have observed a new deformation-twinning mechanism using the high resolution transmission electron microscope in polycrystalline Ag films, zero-strain twinning via nucleation, and the migration of a Σ3{112} incoherent twin boundary (ITB). This twinning mechanism produces a near zero macroscopic strain because the net Burgers vectors either equal zero or are equivalent to a Shockley partial dislocation. This observation provides new insight into the understanding of deformation twinning and confirms a previous hypothesis: detwinning could be accomplished via the nucleation and migration of Σ3{112} ITBs. The zero-strain twinning mechanism may be unique to low staking fault energy metals with implications for their deformation behavior.

  7. Highly deformable and highly fluid vesicles as potential drug delivery systems: theoretical and practical considerations

    PubMed Central

    Romero, Eder Lilia; Morilla, Maria Jose

    2013-01-01

    Vesicles that are specifically designed to overcome the stratum corneum barrier in intact skin provide an efficient transdermal (systemic or local) drug delivery system. They can be classified into two main groups according to the mechanisms underlying their skin interaction. The first group comprises those possessing highly deformable bilayers, achieved by incorporating edge activators to the bilayers or by mixing with certain hydrophilic solutes. The vesicles of this group act as drug carriers that penetrate across hydrophilic pathways of the intact skin. The second group comprises those possessing highly fluid bilayers, owing to the presence of permeation enhancers. The vesicles of this group can act as carriers of drugs that permeate the skin after the barrier of the stratum corneum is altered because of synergistic action with the permeation enhancers contained in the vesicle structure. We have included a detailed overview of the different mechanisms of skin interaction and discussed the most promising preclinical applications of the last five years of Transfersomes® (IDEA AG, Munich, Germany), ethosomes, and invasomes as carriers of antitumoral and anti-inflammatory drugs applied by the topical route. PMID:23986634

  8. Microstructure and Corrosion Behavior of Hot-Deformed and Cold-Strained High-Mn Steels

    NASA Astrophysics Data System (ADS)

    Grajcar, A.; Kciuk, M.; Topolska, S.; Płachcińska, A.

    2016-06-01

    The electrochemical corrosion properties of 26Mn-3Si-3Al and 27Mn-4Si-2Al austenitic steels in two different states were studied in 0.1 M H2SO4 and 3.5% NaCl using potentiodynamic polarization tests. The effect of cold deformation on the microstructure and corrosion behavior of steels was analyzed. In acid solution, both steels exhibited lower corrosion resistance than in chloride solution independently on the steel state (hot-rolled, cold-worked). Cold deformation decreases the corrosion resistance, though this effect is smaller than the effect of chemical composition related to the combined Al + Si addition. All steels showed the evidence of pitting corrosion. The intensive dissolution of Fe and Mn takes place in the acid medium.

  9. High-speed nano-bearings constructed from double-walled carbon nanotubes: Effect of flexile deformation

    NASA Astrophysics Data System (ADS)

    Zhu, Chunzhang; Zhao, Yang

    2013-11-01

    Double-walled carbon nanotubes (DWCNTs) have been proposed to be the leading candidates for high-speed nanobearings owing to superlubric characteristics between adjacent nanotubes. Performance of the DWCNT bearings is closely related to intertube friction, which is influenced by many factors, and in this work, we focus on the issue of flexibility of the nanotubes. Using molecular dynamics simulation, it has been found that considerable deformation of the nanotubes can emerge in the (5, 5)/(18, 0) DWCNT bearing with a length of ˜80 Å if the angular speed of the shaft reaches 1.3 rev/ps. Such flexile deformation results in two distinct states with differing frictional characteristics. One of the two states, the slippery rotation, represents an interim period characterized by in-phase distortions of the inner and outer tubes, while the other state, the resistant rotation, is a steady state with the inner-tube curving lags behind that of the outer tube. Such a lag leads to a considerable increase of circular deflection of the outer tube and a sharp decrease of the minimal distance between tubes, therefore preventing the inner tube from slippery rotation.

  10. Some contributions to the high strain rate deformation of solids and the thermally activated deformation of wood

    NASA Astrophysics Data System (ADS)

    Ferguson, W. George

    2009-08-01

    The behaviour of metals as a function of rate of loading, strain rate, and temperature is discussed in terms of previous work by the author. Strain rates range from 10-3 s-1, obtained in a standard tensile testing machine, to 102 s-1 obtained in a hydraulic piston driven machine and up to 104 s-1, very high strain rates with a Kolsky split Hopkinson bar using shear type loading. At rates less 103 s-1 the strength is a function of strain rate and temperature, is thermally activated and governed by the stress-assisted thermal activation of dislocations across short-range barriers in the crystal. At very high strain rates however the behaviour is controlled by interaction of dislocations with either phonons or electrons, giving a strength proportional to strain rate. The compressive strength of small clear samples of wood, Pinus radiata and Kahikatea, determined over the strain rate range 10-3 s-1 to 103 s-1 as a function of strain rate, temperature and moisture content shows the behaviour to again be thermally activated with the strength a function of stain rate, temperature and moisture content. A rate theory of deformation is developed where the yield behaviour of wood is assumed to result from the stress-assisted thermally activated motion of elementary fibrils over short-range barriers. The moisture is assumed to affect the bond energy between elementary fibrils and the barrier energy is taken to be a linear decreasing function of increasing moisture content and the moisture to act like a plasticiser in separating the elementary fibrils. The theory more than adequately explains the observed behaviour.

  11. Multiscale deformations lead to high toughness and circularly polarized emission in helical nacre-like fibres

    NASA Astrophysics Data System (ADS)

    Zhang, Jia; Feng, Wenchun; Zhang, Huangxi; Wang, Zhenlong; Calcaterra, Heather A.; Yeom, Bongjun; Hu, Ping An; Kotov, Nicholas A.

    2016-02-01

    Nacre-like composites have been investigated typically in the form of coatings or free-standing sheets. They demonstrated remarkable mechanical properties and are used as ultrastrong materials but macroscale fibres with nacre-like organization can improve mechanical properties even further. The fiber form or nacre can, simplify manufacturing and offer new functional properties unknown yet for other forms of biomimetic materials. Here we demonstrate that nacre-like fibres can be produced by shear-induced self-assembly of nanoplatelets. The synergy between two structural motifs--nanoscale brick-and-mortar stacking of platelets and microscale twisting of the fibres--gives rise to high stretchability (>400%) and gravimetric toughness (640 J g-1). These unique mechanical properties originate from the multiscale deformation regime involving solid-state self-organization processes that lead to efficient energy dissipation. Incorporating luminescent CdTe nanowires into these fibres imparts the new property of mechanically tunable circularly polarized luminescence. The nacre-like fibres open a novel technological space for optomechanics of biomimetic composites, while their continuous spinning methodology makes scalable production realistic.

  12. Multiscale deformations lead to high toughness and circularly polarized emission in helical nacre-like fibres

    PubMed Central

    Zhang, Jia; Feng, Wenchun; Zhang, Huangxi; Wang, Zhenlong; Calcaterra, Heather A.; Yeom, Bongjun; Hu, Ping An; Kotov, Nicholas A.

    2016-01-01

    Nacre-like composites have been investigated typically in the form of coatings or free-standing sheets. They demonstrated remarkable mechanical properties and are used as ultrastrong materials but macroscale fibres with nacre-like organization can improve mechanical properties even further. The fiber form or nacre can, simplify manufacturing and offer new functional properties unknown yet for other forms of biomimetic materials. Here we demonstrate that nacre-like fibres can be produced by shear-induced self-assembly of nanoplatelets. The synergy between two structural motifs—nanoscale brick-and-mortar stacking of platelets and microscale twisting of the fibres—gives rise to high stretchability (>400%) and gravimetric toughness (640 J g−1). These unique mechanical properties originate from the multiscale deformation regime involving solid-state self-organization processes that lead to efficient energy dissipation. Incorporating luminescent CdTe nanowires into these fibres imparts the new property of mechanically tunable circularly polarized luminescence. The nacre-like fibres open a novel technological space for optomechanics of biomimetic composites, while their continuous spinning methodology makes scalable production realistic. PMID:26907888

  13. In-situ Phase Transformation and Deformation of Iron at High Pressure andTemperature

    SciTech Connect

    Miyagi, Lowell; Kunz, Martin; Knight, Jason; Nasiatka, James; Voltolini, Marco; Wenk, Hans-Rudolf

    2008-07-01

    With a membrane based mechanism to allow for pressure change of a sample in aradial diffraction diamond anvil cell (rDAC) and simultaneous infra-red laser heating, itis now possible to investigate texture changes during deformation and phasetransformations over a wide range of temperature-pressure conditions. The device isused to study bcc (alpha), fcc (gamma) and hcp (epislon) iron. In bcc iron, room temperature compression generates a texture characterized by (100) and (111) poles parallel to the compression direction. During the deformation induced phase transformation to hcp iron, a subset of orientations are favored to transform to the hcp structure first and generate a texture of (01-10) at high angles to the compression direction. Upon further deformation, the remaining grains transform, resulting in a texture that obeys the Burgers relationship of (110)bcc // (0001)hcp. This is in contrast to high temperature results that indicate that texture is developed through dominant pyramidal {2-1-12}<2-1-13> and basal (0001)-{2-1-10} slip based on polycrystal plasticity modeling. We also observe that the high temperature fcc phase develops a 110 texture typical for fcc metals deformed in compression.

  14. High-K multi-quasiparticle states in 254No

    NASA Astrophysics Data System (ADS)

    Clark, R. M.; Gregorich, K. E.; Berryman, J. S.; Ali, M. N.; Allmond, J. M.; Beausang, C. W.; Cromaz, M.; Deleplanque, M. A.; Dragojević, I.; Dvorak, J.; Ellison, P. A.; Fallon, P.; Garcia, M. A.; Gates, J. M.; Gros, S.; Jeppesen, H. B.; Kaji, D.; Lee, I. Y.; Macchiavelli, A. O.; Morimoto, K.; Nitsche, H.; Paschalis, S.; Petri, M.; Stavsetra, L.; Stephens, F. S.; Watanabe, H.; Wiedeking, M.

    2010-06-01

    We report results from an experiment on the decay of the high-K isomers in 254No. We have been able to establish the decay from the known high-lying four-quasiparticle isomer, which we assign as a K=16 state at an excitation energy of Ex=2.928(3) MeV. The decay of this state passes through a rotational band based on a previously unobserved state at Ex=2.012(2) MeV, which we suggest is based on a two-quasineutron configuration with K=10. This state in turn decays to a rotational band based on the known K=8 isomer, which we infer must also have a two quasineutron configuration. We are able to assign many new gamma-rays associated with the decay of the K=8 isomer, including the identification of a highly K-forbidden ΔK=8 E1 transition to the ground-state band. These results provide valuable new information on the orbitals close to the Fermi surface, pairing correlations, deformation and rotational response, and K-conservation in nuclei of the deformed trans-fermium region.

  15. High-pressure and high temperature deformation studies of polycrystalline diamond

    NASA Astrophysics Data System (ADS)

    Yu, Xiaohui

    2011-03-01

    With Vicker's hardness 120 GPa, shear modulus 535 GPa, diamond is the hardest material known to mankind. However, because diamond is difficult to deform, little is known with regard to its constitutive properties such as yield strength. In this work, we present results obtained at NSLS using deformation-DIA on polycrystalline diamond at different P-T conditions. As expected, even at total strains up to 20%, we did not observe the yield point of diamond at room temperature and a confining pressure of 4 GPa. However, for deformation at 1000 and 1200& circ; C, we observed an plastic flow of diamond at total strains of 10% and 5%, respectively, indicating that diamond weakens rapidly when temperature is over 1000& circ; C. We further derived the micro stress of diamond from peak width analysis, and found that the micro and macro stresses show similar variations with total strain at both room temperature and 1000& circ; C. However, at 1200& circ; C, the micro stress remains constant in entire deformation, indicating that stress is uniformly distributed within diamond particles at 1200& circ; C. We also carried out SEM studies on the recovered samples to investigate the miscrostructures, and find that the grain size of diamond decreases substantially during the deformation, from the initial microns to sub-microns for the room temperature deformation, however, almost doesn't change for the 1200& circ; C.

  16. Deformation of contact surfaces in a vacuum interrupter after high-current interruptions

    NASA Astrophysics Data System (ADS)

    Wang, Haoran; Wang, Zhenxing; Zhou, Zhipeng; Jiang, Yanjun; Wang, Jianhua; Geng, Yingsan; Liu, Zhiyuan

    2016-08-01

    In a high-current interruption, the contact surface in a vacuum interrupter might be severely damaged by constricted vacuum arcs causing a molten area on it. As a result, a protrusion will be initiated by a transient recovery voltage after current zero, enhancing the local electric field and making breakdowns occur easier. The objective of this paper is to simulate the deformation process on the molten area under a high electric field by adopting the finite element method. A time-dependent Electrohydrodynamic model was established, and the liquid-gas interface was tracked by the level-set method. From the results, the liquid metal can be deformed to a Taylor cone if the applied electric field is above a critical value. This value is correlated to the initial geometry of the liquid metal, which increases as the size of the liquid metal decreases. Moreover, the buildup time of a Taylor cone obeys the power law t = k × E-3, where E is the initial electric field and k is a coefficient related to the material property, indicating a temporal self-similar characteristic. In addition, the influence of temperature has little impact on the deformation but has great impact on electron emission. Finally, the possible reason to initiate a delayed breakdown is associated with the deformation. The breakdown does not occur immediately when the voltage is just applied upon the gap but is postponed to several milliseconds later when the tip is formed on the liquid metal.

  17. Sustained High Basal Motion of the Greenland Ice Sheet Revealed by Borehole Deformation

    NASA Technical Reports Server (NTRS)

    Ryser, Claudia; Luthi, Martin P.; Andrews, Lauren C.; Hoffman, Matthew, J.; Catania, Ginny A.; Hawley, Robert L.; Neumann, Thomas A.; Kristensen, Steen S.

    2014-01-01

    Ice deformation and basal motion characterize the dynamical behavior of the Greenland ice sheet (GrIS). We evaluate the contribution of basal motion from ice deformation measurements in boreholes drilled to the bed at two sites in the western marginal zone of the GrIS. We find a sustained high amount of basal motion contribution to surface velocity of 44-73 percent in winter, and up to 90 percent in summer. Measured ice deformation rates show an unexpected variation with depth that can be explained with the help of an ice-flow model as a consequence of stress transfer from slippery to sticky areas. This effect necessitates the use of high-order ice-flow models, not only in regions of fast-flowing ice streams but in all temperate-based areas of the GrIS. The agreement between modeled and measured deformation rates confirms that the recommended values of the temperature-dependent flow rate factor A are a good choice for ice-sheet models.

  18. Interfacial diffusion in high-temperature deformation of composites: A discrete dislocation plasticity investigation

    NASA Astrophysics Data System (ADS)

    Shishvan, Siamak S.; Pollock, Tresa M.; McMeeking, Robert M.; Deshpande, Vikram S.

    2017-01-01

    We present a discrete dislocation plasticity (DDP) framework to analyse the high temperature deformation of multi-phase materials (composites) comprising a matrix and inclusions. Deformation of the phases is by climb-assisted glide of the dislocations while the particles can also deform due to stress-driven interfacial diffusion. The general framework is used to analyse the uniaxial tensile deformation of a composite comprising elastic particles with dislocation plasticity only present in the matrix phase. When dislocation motion is restricted to only glide within the matrix a strong size effect of the composite strength is predicted with the strength increasing with decreasing unit cell size due to dislocations forming pile-ups against the matrix/particle interface. Interfacial diffusion decreases the composite strength as it enhances the elongation of the elastic particles along the loading direction. When dislocation motion occurs by climb-assisted glide within the matrix the size effect of the strength is reduced as dislocations no longer arrange high energy pile-up structures but rather form lower energy dislocation cell networks. While interfacial diffusion again reduces the composite strength, in contrast to continuum plasticity predictions, the elongation of the particles is almost independent of the interfacial diffusion constant. Rather, in DDP the reduction in composite strength due to interfacial diffusion is a result of changes in the dislocation structures within the matrix and the associated enhanced dislocation climb rates in the matrix.

  19. Deformation Mechanisms and High Strain Rate Properties of Magnesium (Mg) and Mg Alloys

    DTIC Science & Technology

    2012-08-01

    Deformation Mechanisms and High Strain Rate Properties of Magnesium (Mg) and Mg Alloys by Bin Li, Logan Shannahan, Evan Ma, Kaliatt T. Ramesh...Properties of Magnesium (Mg) and Mg Alloys Bin Li, Logan Shannahan, Evan Ma, and Kaliatt T. Ramesh Johns Hopkins University Suveen Mathaudhu...Mechanisms and High Strain Rate Properties of Magnesium (Mg) and Mg Alloys 5a. CONTRACT NUMBER W911NF-06-2-0006 5b. GRANT NUMBER 5c. PROGRAM ELEMENT

  20. Nonlinear viscoelastic response of highly filled elastomers under multiaxial finite deformation

    NASA Technical Reports Server (NTRS)

    Peng, Steven T. J.; Landel, Robert F.

    1990-01-01

    A biaxial tester was used to obtain precise biaxial stress responses of highly filled, high strain capability elastomers. Stress-relaxation experiments show that the time-dependent part of the relaxation response can be reasonably approximated by a function which is strain and biaxiality independent. Thus, isochronal data from the stress-relaxation curves can be used to determine the stored energy density function. The complex behavior of the elastomers under biaxial deformation may be caused by dewetting.

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

    PubMed Central

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

    2016-01-01

    Objective. The cause of considerable elasticity and plasticity of human dentin is discussed in the relationship with its microstructure. Methods. Structural state of teenage and mature human dentin is examined by using XRD and TEM techniques, and their deformation behavior under compression is studied as well. Result. XRD study has shown that crystallographic type of calcium hydroxyapatite in human dentin (calcium hydrogen phosphate hydroxide Ca9HPO4(PO4)5OH; Space Group P63/m (176); a = 9,441 A; c = 6,881 A; c/a = 0,729; Crystallite (Scherrer) 200 A) is the same for these age groups. In both cases, dentin matrix is X-ray amorphous. According to TEM examination, there are amorphous and ultrafine grain phases in teenage and mature dentin. Mature dentin is stronger on about 20% than teenage dentin, while teenage dentin is more elastic on about 20% but is less plastic on about 15% than mature dentin. Conclusion. The amorphous phase is dominant in teenage dentin, whereas the ultrafine grain phase becomes dominant in mature dentin. Mechanical properties of human dentin under compression depend on its structural state, too. PMID:26989416

  2. Wavelet analysis deformation monitoring data of high-speed railway bridge

    NASA Astrophysics Data System (ADS)

    Tang, ShiHua; Huang, Qing; Zhou, Conglin; Xu, HongWei; Liu, YinTao; Li, FeiDa

    2015-12-01

    Deformation monitoring data of high-speed railway bridges will inevitably be affected because of noise pollution, A deformation monitoring point of high-speed railway bridge was measurd by using sokkia SDL30 electronic level for a long time,which got a large number of deformation monitoring data. Based on the characteristics of the deformation monitoring data of high-speed railway bridge, which contain lots of noise. Based on the MATLAB software platform, 120 groups of deformation monitoring data were applied to analysis of wavelet denoising.sym6,db6 wavelet basis function were selected to analyze and remove the noise.The original signal was broken into three layers wavelet,which contain high frequency coefficients and low frequency coefficients.However, high frequency coefficient have plenty of noise.Adaptive method of soft and hard threshold were used to handle in the high frequency coefficient.Then,high frequency coefficient that was removed much of noise combined with low frequency coefficient to reconstitute and obtain reconstruction wavelet signal.Root Mean Square Error (RMSE) and Signal-To-Noise Ratio (SNR) were regarded as evaluation index of denoising,The smaller the root mean square error and the greater signal-to-noise ratio indicate that them have a good effect in denoising. We can surely draw some conclusions in the experimental analysis:the db6 wavelet basis function has a good effect in wavelet denoising by using a adaptive soft threshold method,which root mean square error is minimum and signal-to-noise ratio is maximum.Moreover,the reconstructed image are more smooth than original signal denoising after wavelet denoising, which removed noise and useful signal are obtained in the original signal.Compared to the other three methods, this method has a good effect in denoising, which not only retain useful signal in the original signal, but aiso reach the goal of removing noise. So, it has a strong practical value in a actual deformation monitoring

  3. High-pressure and high temperature deformation studies of polycrystalline diamond

    NASA Astrophysics Data System (ADS)

    Yu, X.; Zhang, J.; Xu, H.; Wang, L.; Zhao, Y.

    2010-12-01

    With a Vicker’s hardness up to 120 GPa, diamond is the hardest material known to mankind. Diamond also has the highest bulk modulus (443 GPa) and the highest shear modulus (535 GPa) among all materials. However, because diamond is difficult to deform, little is known to date with regard to its constitutive properties such as yield strength and flow stress. In this work, we present results obtained at X17B2 of NSLS using the deformation-DIA (D-DIA) on cylindrical polycrystalline diamond at different pressure and temperature conditions. As expected, even at total axial strains up to 30%, we did not observe the yield point of diamond at room temperature and a confining pressure of 4 GPa. However, for deformation at 1000 and 1200 C, we observed an ultimate plastic flow of diamond at total axial strains of 10% and 5%, respectively, indicating that diamond weakens rapidly when temperature is over 1000 C. We further derived the microscopic stress of diamond during the deformation from the peak profile analysis, and we found that the microscopic and macroscopic stresses show similar variations with the total axial strain at both room temperature and 1000 C. However, at 1200 C, the microscopic stress remains fairly constant in the entire course of deformation, indicating that the stress at this higher temperature is uniformly distributed within polycrystalline diamond particles during the deformation. We also carried out SEM and TEM studies on the recovered samples to investigate their miscrostructures, and we find that the grain size of diamond decreases substantially during the deformation, from the initial 4-6 microns to sub-microns. More details of the experimental results will be presented and discussed.

  4. Finite element analysis of low-cost membrane deformable mirrors for high-order adaptive optics

    NASA Astrophysics Data System (ADS)

    Winsor, Robert S.; Sivaramakrishnan, Anand; Makidon, Russell B.

    1999-10-01

    We demonstrate the feasibility of glass membrane deformable mirror (DM) support structures intended for very high order low-stroke adaptive optics systems. We investigated commercially available piezoelectric ceramics. Piezoelectric tubes were determined to offer the largest amount of stroke for a given amount of space on the mirror surface that each actuator controls. We estimated the minimum spacing and the maximum expected stroke of such actuators. We developed a quantitative understanding of the response of a membrane mirror surface by performing a Finite Element Analysis (FEA) study. The results of the FEA analysis were used to develop a design and fabrication process for membrane deformable mirrors of 200 - 500 micron thicknesses. Several different values for glass thickness and actuator spacing were analyzed to determine the best combination of actuator stoke and surface deformation quality. We considered two deformable mirror configurations. The first configuration uses a vacuum membrane attachment system where the actuator tubes' central holes connect to an evacuated plenum, and atmospheric pressure holds the membrane against the actuators. This configuration allows the membrane to be removed from the actuators, facilitating easy replacement of the glass. The other configuration uses precision bearing balls epoxied to the ends of the actuator tubes, with the glass membrane epoxied to the ends of the ball bearings. While this kind of DM is not serviceable, it allows actuator spacings of 4 mm, in addition to large stroke. Fabrication of a prototype of the latter kind of DM was started.

  5. Large-deformation and high-strength amorphous porous carbon nanospheres

    NASA Astrophysics Data System (ADS)

    Yang, Weizhu; Mao, Shimin; Yang, Jia; Shang, Tao; Song, Hongguang; Mabon, James; Swiech, Wacek; Vance, John R.; Yue, Zhufeng; Dillon, Shen J.; Xu, Hangxun; Xu, Baoxing

    2016-04-01

    Carbon is one of the most important materials extensively used in industry and our daily life. Crystalline carbon materials such as carbon nanotubes and graphene possess ultrahigh strength and toughness. In contrast, amorphous carbon is known to be very brittle and can sustain little compressive deformation. Inspired by biological shells and honeycomb-like cellular structures in nature, we introduce a class of hybrid structural designs and demonstrate that amorphous porous carbon nanospheres with a thin outer shell can simultaneously achieve high strength and sustain large deformation. The amorphous carbon nanospheres were synthesized via a low-cost, scalable and structure-controllable ultrasonic spray pyrolysis approach using energetic carbon precursors. In situ compression experiments on individual nanospheres show that the amorphous carbon nanospheres with an optimized structure can sustain beyond 50% compressive strain. Both experiments and finite element analyses reveal that the buckling deformation of the outer spherical shell dominates the improvement of strength while the collapse of inner nanoscale pores driven by twisting, rotation, buckling and bending of pore walls contributes to the large deformation.

  6. Large-deformation and high-strength amorphous porous carbon nanospheres

    PubMed Central

    Yang, Weizhu; Mao, Shimin; Yang, Jia; Shang, Tao; Song, Hongguang; Mabon, James; Swiech, Wacek; Vance, John R.; Yue, Zhufeng; Dillon, Shen J.; Xu, Hangxun; Xu, Baoxing

    2016-01-01

    Carbon is one of the most important materials extensively used in industry and our daily life. Crystalline carbon materials such as carbon nanotubes and graphene possess ultrahigh strength and toughness. In contrast, amorphous carbon is known to be very brittle and can sustain little compressive deformation. Inspired by biological shells and honeycomb-like cellular structures in nature, we introduce a class of hybrid structural designs and demonstrate that amorphous porous carbon nanospheres with a thin outer shell can simultaneously achieve high strength and sustain large deformation. The amorphous carbon nanospheres were synthesized via a low-cost, scalable and structure-controllable ultrasonic spray pyrolysis approach using energetic carbon precursors. In situ compression experiments on individual nanospheres show that the amorphous carbon nanospheres with an optimized structure can sustain beyond 50% compressive strain. Both experiments and finite element analyses reveal that the buckling deformation of the outer spherical shell dominates the improvement of strength while the collapse of inner nanoscale pores driven by twisting, rotation, buckling and bending of pore walls contributes to the large deformation. PMID:27072412

  7. High Resolution Deformation Time Series Estimation for Distributed Scatterers Using Terrasar-X Data

    NASA Astrophysics Data System (ADS)

    Goel, K.; Adam, N.

    2012-07-01

    In recent years, several SAR satellites such as TerraSAR-X, COSMO-SkyMed and Radarsat-2 have been launched. These satellites provide high resolution data suitable for sophisticated interferometric applications. With shorter repeat cycles, smaller orbital tubes and higher bandwidth of the satellites; deformation time series analysis of distributed scatterers (DSs) is now supported by a practical data basis. Techniques for exploiting DSs in non-urban (rural) areas include the Small Baseline Subset Algorithm (SBAS). However, it involves spatial phase unwrapping, and phase unwrapping errors are typically encountered in rural areas and are difficult to detect. In addition, the SBAS technique involves a rectangular multilooking of the differential interferograms to reduce phase noise, resulting in a loss of resolution and superposition of different objects on ground. In this paper, we introduce a new approach for deformation monitoring with a focus on DSs, wherein, there is no need to unwrap the differential interferograms and the deformation is mapped at object resolution. It is based on a robust object adaptive parameter estimation using single look differential interferograms, where, the local tilts of deformation velocity and local slopes of residual DEM in range and azimuth directions are estimated. We present here the technical details and a processing example of this newly developed algorithm.

  8. High-temperature tensile deformation behavior of aluminum oxide with and without an applied electric field

    NASA Astrophysics Data System (ADS)

    Campbell, James

    1998-12-01

    Ceramics are usually considered to be brittle, but under certain conditions some ceramics exhibit a large degree of ductility. They are fine-grained and exhibit superplastic behavior when deformed at high temperatures and low stresses. Whereas superplasticity gives enhanced ductility to metals, it may be the only method for imparting large plasticity to ceramics. Electric fields have been shown to increase ductility, reduce flow stress and reduce cavitation in the superplastic forming of 7475 Al and yttria-stabilized zirconia. Thus, the concurrent application of an electric field may give improved superplastic properties and increased plasticity to a marginally ductile ceramic such as aluminum oxide (alpha-alumina). Fine-grained alumina tensile specimens, formed by dry pressing and sintering a spray-dried powder, were tested in tension at high temperature with and without an electric field of 300 V/cm. Constant strain rate, strain rate cycling and stress relaxation tests were performed. The effects of an electric field on the ductility, flow stress, cavitation and parameters of the Weertman-Dorn deformation equation were measured. Without an electric field, the following deformation parameters were found: the stress exponent n = 2.2, the grain size exponent p = 1.9, the activation energy Q = 490 kJ/mol and the threshold stress sigmao ≈ 0 MPa, indicating structural superplasticity where grain boundary sliding is the predominant deformation mode and was likely accommodated by the motion of grain boundary dislocations. An electric field of 300 V/cm gave a Joule heating temperature increase of ˜30°C and caused the alumina to swell 5--25% (increasing with time), even while under no applied stress, thereby reducing its ductility and flow stress. After correcting for Joule heating and swelling there was still a significant flow stress reduction produced by the field and the following deformation parameters were found: n = 2.2, p = 1.9, Q = 950 kJ/mol and sigmao ≈ 0

  9. Grain size effects on the high strain rate deformation of copper

    NASA Astrophysics Data System (ADS)

    Stevenson, Michael Earle

    The high strain rate (>104/s) mechanical properties of OFHC copper were studied by the Taylor impact test for a series of copper grain sizes from 31 to 152 mum. The results are analyzed by both analytical and finite element. There is a significant increase in the dynamic strength of OFHC copper for strain rates greater than approximately 104/s. This strength increase is also dependent upon the grain size of the OFHC copper prior to testing and follows a classical Hall-Petch relationship. In addition to the analytical and finite element models, a universal dynamic stress-strain curve was developed and constructed for each grain size of the OFHC copper. The characterization parameters determined from the universal dynamic stress-strain curve are also grain size dependent. Many of these parameters also follow the classical Hall-Petch trend. Post-impact microstructures of the copper can be generalized into five distinct regions. Beginning at the specimen impact face, those regions are: (i) a nanocrystalline, or sub-micron grain size layer; (ii) a dynamically recrystallized region; (iii) a region of high density (111)[112¯] twinning; (iv) a section dominated by dislocation plastic flow, or slip and (v) the specimen portion where the deformation is completely elastic. The five regions can be related to the mechanical properties derived from the individual models and the universal dynamic stress-strain curve with consideration of the initial microstructure of the copper. The results of this dissertation suggest that there is a direct linkage between the dynamic mechanical state of stress during the impact tests and both the initial and final metallurgical microstructures of the copper.

  10. High-speed quantitative phase imaging of dynamic thermal deformation in laser irradiated films

    NASA Astrophysics Data System (ADS)

    Taylor, Lucas N.; Brown, Andrew K.; Olson, Kyle D.; Talghader, Joseph J.

    2015-11-01

    We present a technique for high-speed imaging of the dynamic thermal deformation of transparent substrates under high-power laser irradiation. Traditional thermal sensor arrays are not fast enough to capture thermal decay events. Our system adapts a Mach-Zender interferometer, along with a high-speed camera to capture phase images on sub-millisecond time-scales. These phase images are related to temperature by thermal expansion effects and by the change of refractive index with temperature. High power continuous-wave and long-pulse laser damage often hinges on thermal phenomena rather than the field-induced effects of ultra-short pulse lasers. Our system was able to measure such phenomena. We were able to record 2D videos of 1 ms thermal deformation waves, with 6 frames per wave, from a 100 ns, 10 mJ Q-switched Nd:YAG laser incident on a yttria-coated glass slide. We recorded thermal deformation waves with peak temperatures on the order of 100 degrees Celsius during non-destructive testing.

  11. Structural and phase state and deformation behavior of the hydrogenated ultrafine-grained Zr-1Nb alloy

    NASA Astrophysics Data System (ADS)

    Stepanova, E. N.; Grabovetskaya, G. P.; Mishin, I. P.; Kudiiarov, V. N.

    2016-11-01

    The paper investigates the effect of hydrogenation towards the concentration of 0.33 wt % on the structural and phase state and the deformation process development during tension of the ultrafine-grained Zr-1 wt % Nb alloy (hereinafter Zr-1Nb) at the temperature range of 293-973 K. Hydrogen presence in the alloy in solid solution and hydride precipitates are found that results in an increase of its strength and plastic characteristics at room temperature. At elevated temperatures hydride dissolution activates dislocation motion that leads to strength characteristics reduction and to rise of deformation-to-failure.

  12. Effect of prior deformation on microstructural development and Laves phase precipitation in high-chromium stainless steel.

    PubMed

    Hsiao, Z-W; Chen, D; Kuo, J-C; Lin, D-Y

    2017-04-01

    This study investigated the influence of deformation on precipitation behaviour and microstructure change during annealing. Here, the prior deformation of high-chromium stainless steel was tensile deformation of 3%, 6% and 10%, and the specimens were then annealed at 700˚C for 10 h. The specimens were subsequently analyzed using backscattered electron image and electron backscattering diffraction measurements with SEM. Compared with the deformation microstructure, the grains revealed no preferred orientation. The precipitates of TiN and NbC were formed homogenously in the grain interior and at grain boundaries after annealing. Fine Laves phase precipitates were observed in grains and along subgrain boundaries as the deformation increased. Furthermore, the volume fraction of Laves phase increased, but the average particle diameter of precipitate was reduced as the deformation increased.

  13. Deformation behaviour and 6H-LPSO structure formation at nanoindentation in lamellar high Nb containing TiAl alloy

    NASA Astrophysics Data System (ADS)

    Song, L.; Xu, X. J.; Peng, C.; Wang, Y. L.; Liang, Y. F.; Shang, S. L.; Liu, Z. K.; Lin, J. P.

    2015-02-01

    Microstructure and deformation mechanisms at a nanoindentation in the lamellar colony of high Nb containing TiAl alloy have been studied using the focused ion beam and the transmission electron microscopy. Considerable deformation twins are observed around the nanoindentation, and a strain gradient is generated. A continuous change in the bending angle of the lamellar structure can be derived, and a strain-induced grain refinement process is observed as various active deformations split the γ grains into subgrains. In addition to all possible deformation mechanisms (ordinary dislocation, super-dislocation and deformation twining) activated due to the heavy plastic deformation, a 6-layer hexagonal (6H) long-period stacking ordered structure is identified for the first time near the contact zone and is thought to be closely related to the glide of partial dislocations.

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

    PubMed

    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.

  15. Steady state deformation of the Coso Range, east central California, inferred from satellite radar interferometry

    USGS Publications Warehouse

    Wicks, C.W.; Thatcher, W.; Monastero, F.C.; Hasting, M.A.

    2001-01-01

    Observations of deformation from 1992 to 1997 in the southern Coso Range using satellite radar interferometry show deformation rates of up to 35 mm yr-1 in an area ???10 km by 15 km. The deformation is most likely the result of subsidence in an area around the Coso geothermal field. The deformation signal has a short-wavelength component, related to production in the field, and a long-wavelength component, deforming at a constant rate, that may represent a source of deformation deeper than the geothermal reservoir. We have modeled the long-wavelength component of deformation and inferred a deformation source at ???4 km depth. The source depth is near the brittle-ductile transition depth (inferred from seismicity) and ???1.5 km above the top of the rhyolite magma body that was a source for the most recent volcanic eruption in the Coso volcanic field [Manley and Bacon, 2000]. From this evidence and results of other studies in the Coso Range, we interpret the source to be a leaking deep reservoir of magmatic fluids derived from a crystallizing rhyolite magma body.

  16. Deformable mirrors for intra-cavity use in high-power thin-disk lasers.

    PubMed

    Piehler, Stefan; Dietrich, Tom; Wittmüss, Philipp; Sawodny, Oliver; Ahmed, Marwan Abdou; Graf, Thomas

    2017-02-20

    We present deformable mirrors for the intra-cavity use in high-power thin-disk laser resonators. The refractive power of these mirrors is continuously adaptable from -0.7 m-1 to 0.3 m-1, corresponding to radii of curvature ranging between 2.86 m (convex) and 6.67 m (concave). The optimized shape of the mirror membrane enables a very low peak-to-valley deviation from a paraboloid deformation over a large area. With the optical performance of our mirrors being equal to that of standard HR mirrors, we were able to demonstrate the tuning of the beam quality of a thin-disk laser in a range of M2 = 3 to M2 = 1 during laser operation at output powers as high as 1.1 kW.

  17. Present-day deformation across the Basin and Range Province, western United States

    USGS Publications Warehouse

    Thatcher, W.; Foulger, G.R.; Julian, B.R.; Svarc, J.; Quilty, E.; Bawden, G.W.

    1999-01-01

    The distribution of deformation within the Basin and Range province was determined from 1992, 1996, and 1998 surveys of a dense, 800-kilometer- aperture, Global Positioning System network, Internal deformation generally follows the pattern of Holocene fault distribution and is concentrated near the western extremity of the province, with lesser amounts focused near the eastern boundary. Little net deformation occurs across the central 500 kilometers of the network in western Utah and eastern Nevada. Concentration of deformation adjacent to the rigid Sierra Nevada block indicates that external plate-driving forces play an important role in driving deformation, modulating the extensional stress field generated by internal buoyancy forces that are due to lateral density gradients and topography near the province boundaries.

  18. Aluminium. II - A review of deformation properties of high purity aluminium and dilute aluminium alloys.

    NASA Technical Reports Server (NTRS)

    Reed, R. P.

    1972-01-01

    The elastic and plastic deformation behavior of high-purity aluminum and of dilute aluminum alloys is reviewed. Reliable property data, including elastic moduli, elastic coefficients, tensile, creep, fatigue, hardness, and impact are presented. Single crystal tensile results are discussed. Rather comprehensive reference lists, containing publications of the past 20 years, are included for each of the above categories. Defect structures and mechanisms responsible for mechanical behavior are presented. Strengthening techniques (alloys, cold work, irradiation, quenching, composites) and recovery are briefly reviewed.

  19. Deformation and annealing behavior of heavily drawn oxygen-free high-conductivity (OFHC) copper

    NASA Astrophysics Data System (ADS)

    Waryoba, Daudi Rigenda

    Conductor wires used in pulsed high-field magnets require metallic materials with a beneficial combination of high mechanical strength to resist the Lorentz forces and high electrical conductivity to limit temperature excursions due to Joule heating. To achieve the required strength, most conductors are fabricated from microcomposite materials using the work hardening effect after heavy cold deformation such as wire drawing. Since the microstructure and texture of these microcomposites are complex, a detailed systematic study of these materials requires a separate study of the individual phases. This work presents a comprehensive study of the microstructure and microtexture evolution during deformation, and subsequent annealing of heavily deformed OFHC copper wires. Analytical tools used for investigation include optical microscopy, scanning electron microscopy (SEM), orientation-imaging microscopy (OIM) in SEM, and transmission electron microscopy (TEM). Mechanical properties were evaluated by tensile and microhardness testing. Some of the key features of the as-drawn wire are elongated grain size and shear bands. The intensity of the shear bands increased with strain. The ultimate tensile strength (UTS) and the microhardness of the heavily cold-drawn copper wires increased with strain, reached a saturation point and dropped at higher deformation strain. Deformation did not significantly alter the electrical conductivity of the wires. Deformed and recovered microstructures were characterized by a strong<111>+weak<100> duplex fiber texture. Nucleation of recrystallized grains occurred at shear bands and resulted in randomization of texture. On the other hand, recrystallization produced a strong<100>+weak<111>, which later changed to a <111> fiber texture during abnormal grain growth. A detailed analysis showed that recrystallization was a growth-controlled mechanism, and proceeds from the outer surface to the core. Interestingly, secondary recrystallization was

  20. Multitemporal InSAR analysis at Betic-Rif arc: transient and steady state ground deformation style varieties

    NASA Astrophysics Data System (ADS)

    Fernandez, J.; Gonzalez, P.

    2010-12-01

    We present results of the analysis of multitemporal Differential Synthetic Aperture Radar Interferometry (DInSAR) at the Betics-Rif arc. We exploited a collected database with more than 400 SAR images from ERS and ENVISAT satellites from 6 descending tracks in South Spain and one ascending and one descending track in Northern Morocco (Alhucemas/Al-hoceima area). We compute time series of displacements, taking care on the occurrence of significant shallow earthquakes (clear temporal discontinuities) at the phase-screen atmospheric filter step. Ground deformation velocity maps indicate a large variety in ground deformation styles from clear anthropogenic to step-wise and steady-state tectonic motions. Here, we present preliminary results of significant deformation occurring at several places along the internal zone of the arc, which guarantee discussion and foster later investigations.

  1. Severe plastic deformation processing and high strain rate superplasticity in an aluminum matrix composite

    SciTech Connect

    Mishra, R.S.; McFadden, S.X.; Mukherjee, A.K.; Valiev, R.Z.; Islamgaliev, R.K.

    1999-04-23

    Metal matrix composites possess an attractive set of properties for structural applications. For example, reinforcement of conventional aluminum alloys with second phase ceramic particulates increases the stiffness, high temperature strength, etc. A drawback of ceramic phase reinforcement is that it makes machining of components difficult. Superplastic forming is quite attractive for hard-to-machine materials like composites. A number of aluminum matrix composites exhibit superplasticity. The most attractive feature of superplasticity in aluminum matrix composite is the high strain rate (10{sup {minus}2}--10{sup 1} s{sup {minus}1}) for optimum ductility. This is significantly higher than the optimum superplastic strain rates of 10{sup {minus}4}--10{sup {minus}3} s{sup {minus}1} in conventional fine grained alloys. The optimum superplasticity in aluminum matrix composites is influenced by the thermo-mechanical processing. In the last five years or so, a number of aluminum alloys have been processes by severe plastic deformation (SePD). Severe plastic deformation processing leads to ultrafine grained aluminum alloys with attractive superplastic properties. In this short paper the authors report on successful processing of an ultrafine grained aluminum matrix composite by severe plastic deformation technique. The SePD processes 2009 Al-SiC{sub 2} composite exhibits high strain rate superplasticity.

  2. Stigma, deforming metaphors and patients' moral experience of multibacillary leprosy in Sobral, Ceará State, Brazil.

    PubMed

    Nations, Marilyn K; Lira, Geison Vasconcelos; Catrib, Ana Maria Fontenelle

    2009-06-01

    In response to the call for a new Science of Stigma, this anthropological study investigates the moral experience of patients diagnosed with severe multibacillary leprosy. From 2003 to 2006, fieldwork was conducted in the so-called 'United-States-of-Sobral', in Ceará State, Northeast Brazil. Sobral is highly endemic for leprosy, despite intensified eradication efforts and a 30% increase in primary care coverage since 1999. Of 329 active leprosy cases at two public clinics, 279 multibacillary patients were identified and six information-rich cases selected for in-depth ethnographic analysis, utilizing illness narratives, key-informant interviews, home visits, participant-observation of clinical consultations and semi-structured interviews with physicians. A 'contextualized semantic interpretation' revealed four leprosy metaphors: a repulsive rat's disease, a racist skin rash, a biblical curse and lethal leukemia. Far from value-free pathology, the disease is imbued with moral significance. Patients' multivocalic illness constructions contest physicians' disease discourse. 'Skin Spot Day' discriminates more than educates. Patients' 'non-compliance' with effective multi-drug therapy is due to demoralizing stigma more than a rejection of care. 'Social leprosy' in Northeast Brazil deforms patients' moral reputations and personal dignity.

  3. High-rate Plastic Deformation of Nanocrystalline Tantalum to Large Strains: Molecular Dynamics Simulation

    SciTech Connect

    Rudd, R E

    2009-02-05

    Recent advances in the ability to generate extremes of pressure and temperature in dynamic experiments and to probe the response of materials has motivated the need for special materials optimized for those conditions as well as a need for a much deeper understanding of the behavior of materials subjected to high pressure and/or temperature. Of particular importance is the understanding of rate effects at the extremely high rates encountered in those experiments, especially with the next generation of laser drives such as at the National Ignition Facility. Here we use large-scale molecular dynamics (MD) simulations of the high-rate deformation of nanocrystalline tantalum to investigate the processes associated with plastic deformation for strains up to 100%. We use initial atomic configurations that were produced through simulations of solidification in the work of Streitz et al [Phys. Rev. Lett. 96, (2006) 225701]. These 3D polycrystalline systems have typical grain sizes of 10-20 nm. We also study a rapidly quenched liquid (amorphous solid) tantalum. We apply a constant volume (isochoric), constant temperature (isothermal) shear deformation over a range of strain rates, and compute the resulting stress-strain curves to large strains for both uniaxial and biaxial compression. We study the rate dependence and identify plastic deformation mechanisms. The identification of the mechanisms is facilitated through a novel technique that computes the local grain orientation, returning it as a quaternion for each atom. This analysis technique is robust and fast, and has been used to compute the orientations on the fly during our parallel MD simulations on supercomputers. We find both dislocation and twinning processes are important, and they interact in the weak strain hardening in these extremely fine-grained microstructures.

  4. High-quality four-dimensional cone-beam CT by deforming prior images.

    PubMed

    Wang, Jing; Gu, Xuejun

    2013-01-21

    Due to a limited number of projections at each phase, severe view aliasing artifacts are present in four-dimensional cone beam computed tomography (4D-CBCT) when reconstruction is performed using conventional algorithms. In this work, we aim to obtain high-quality 4D-CBCT of lung cancer patients in radiation therapy by deforming the planning CT. The deformation vector fields (DVF) to deform the planning CT are estimated through matching the forward projection of the deformed prior image and measured on-treatment CBCT projection. The estimation of the DVF is formulated as an unconstrained optimization problem, where the objective function to be minimized is the sum of the squared difference between the forward projection of the deformed planning CT and the measured 4D-CBCT projection. A nonlinear conjugate gradient method is used to solve the DVF. As the number of the variables in the DVF is much greater than the number of measurements, the solution to such a highly ill-posed problem is very sensitive to the initials during the optimization process. To improve the estimation accuracy of DVF, we proposed a new strategy to obtain better initials for the optimization. In this strategy, 4D-CBCT is first reconstructed by total variation minimization. Demons deformable registration is performed to register the planning CT and the 4D-CBCT reconstructed by total variation minimization. The resulted DVF from demons registration is then used as the initial parameters in the optimization process. A 4D nonuniform rotational B-spline-based cardiac-torso (NCAT) phantom and a patient 4D-CBCT are used to evaluate the algorithm. Image quality of 4D-CBCT is substantially improved by using the proposed strategy in both NCAT phantom and patient studies. The proposed method has the potential to improve the temporal resolution of 4D-CBCT. Improved 4D-CBCT can better characterize the motion of lung tumors and will be a valuable tool for image-guided adaptive radiation therapy.

  5. High-temperature wear and deformation processes in metal matrix composites

    NASA Astrophysics Data System (ADS)

    Singh, J.; Alpas, A. T.

    1996-10-01

    Dry-sliding wear behaviors of a particulate-reinforced aluminum matrix composite 6061 Al-20 pet A12O3 and an unreinforced 6061 Al alloy were investigated in the temperature range 25 °C to 500 °C against a SAE 52100 bearing steel counterface. Experiments were carried out at a constant sliding speed of 0.2 m·s- at different test loads. The deformation behavior of the materials was studied by performing uniaxial compression tests in the same temperature range as the wear tests. Both alloys showed a mild-to-severe wear transition above a certain test temperature. In the mild wear regime, the wear rate and the coefficient of friction of the unreinforced 6061 Al decreased slightly with temperature, but the temperature had almost no effect on the wear rate and the coefficient of friction of the 6061 Al-20 pet Al2O3 in the same regime. Particulate reinforcement led to an increase in the transition temperature and a 50 to 70 pet improvement in the wear resistance in the severe wear regime. This was attributed to the formation of tribological layers consisting of comminuted A12O3 particles at the contact surface. High-temperature compression tests showed that the flow strength of 6061 Al-20 pet A12O3 and 6061 Al decreased monotonically with temperature and both alloys exhibited a work-softening behavior at temperatures higher than the inflection point on the flow stress vs temperature curves. The logarithmic maximum stress vs reciprocal temperature relationship was not linear, indicating that the deformation processes were too complicated to be characterized by a single activation energy over the whole temperature range. For the range of 250 °C to 450 °C, the activation energy for deformation was estimated to be 311 kJ·mol-1; for both the matrix alloy and the composite. Severe wear proceeded by thermally activated deformation processes involving dynamic recrystallization along a subsurface strain gradient. A power-Arrhenius type relationship was found to describe well

  6. High-quality four-dimensional cone-beam CT by deforming prior images

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Gu, Xuejun

    2013-01-01

    Due to a limited number of projections at each phase, severe view aliasing artifacts are present in four-dimensional cone beam computed tomography (4D-CBCT) when reconstruction is performed using conventional algorithms. In this work, we aim to obtain high-quality 4D-CBCT of lung cancer patients in radiation therapy by deforming the planning CT. The deformation vector fields (DVF) to deform the planning CT are estimated through matching the forward projection of the deformed prior image and measured on-treatment CBCT projection. The estimation of the DVF is formulated as an unconstrained optimization problem, where the objective function to be minimized is the sum of the squared difference between the forward projection of the deformed planning CT and the measured 4D-CBCT projection. A nonlinear conjugate gradient method is used to solve the DVF. As the number of the variables in the DVF is much greater than the number of measurements, the solution to such a highly ill-posed problem is very sensitive to the initials during the optimization process. To improve the estimation accuracy of DVF, we proposed a new strategy to obtain better initials for the optimization. In this strategy, 4D-CBCT is first reconstructed by total variation minimization. Demons deformable registration is performed to register the planning CT and the 4D-CBCT reconstructed by total variation minimization. The resulted DVF from demons registration is then used as the initial parameters in the optimization process. A 4D nonuniform rotational B-spline-based cardiac-torso (NCAT) phantom and a patient 4D-CBCT are used to evaluate the algorithm. Image quality of 4D-CBCT is substantially improved by using the proposed strategy in both NCAT phantom and patient studies. The proposed method has the potential to improve the temporal resolution of 4D-CBCT. Improved 4D-CBCT can better characterize the motion of lung tumors and will be a valuable tool for image-guided adaptive radiation therapy.

  7. Development of a Two-Phase Model for the Hot Deformation of Highly-Alloyed Aluminum

    SciTech Connect

    A. J. Beaudoin; J. A. Dantzig; I. M. Robertson; B. E. Gore; S. F. Harnish; H. A. Padilla

    2005-10-31

    Conventional processing methods for highly alloyed aluminum consist of ingot casting, followed by hot rolling and thermal treatments. Defects result in lost productivity and wasted energy through the need to remelt and reprocess the material. This research centers on developing a fundamental understanding for deformation of wrought 705X series alloys, a key alloy system used in structural airframe applications. The development of damage at grain boundaries is characterized through a novel test that provides initiation of failure while preserving a controlled deformation response. Data from these mechanical tests are linked to computer simulations of the hot rolling process through a critical measure of damage. Transmission electron microscopy provides fundamental insight into deformation at these high working temperatures, and--in a novel link between microscale and macroscale response--the evolution of microstructure (crystallographic orientation) provides feedback for tuning of friction in the hot rolling process. The key product of this research is a modeling framework for the analysis of industrial hot rolling.

  8. High-Temperature Deformation of Dry Diabase with Application to Tectonics on Venus

    NASA Technical Reports Server (NTRS)

    Mackwell, S. J.; Zimmerman, M. E.; Kohlstedt, D. L.

    1998-01-01

    We have performed an experimental study to quantify the high-temperature creep behavior of natural diabase rocks under dry deformation conditions. Samples of both Maryland diabase and Columbia diabase were investigated to measure the effects of temperature, oxygen fugacity, and plagioclase-to-pyroxene ratio on creep strength. Flow laws determined for creep of these diabases were characterized by an activation energy of Q = 485 +/- 30 kJ/mol and a stress exponent of n = 4.7 +/- 0.6, indicative of deformation dominated by dislocation creep processes. Although n and Q are the same for the two rocks within experimental error, the Maryland diabase, which has the lower plagioclase content, is significantly stronger than the Columbia diabase. Thus the modal abundance of the various minerals plays an important role in defining rock strength. Within the s ample-to-sample variation, no clear influence of oxygen fugacity on creep strength could be discerned for either rock. The dry creep strengths of both rocks are significantly greater than values previously measured on diabase under "as-received" or wet conditions. Application of these results to the present conditions in the lithosphere on Venus predicts a high viscosity crust with strong dynamic coupling between mantle convection and crustal deformation, consistent with measurements of topography and gravity for that planet.

  9. Deformation behavior of SS400 Thick plate by high-frequency-induction-heating-based line heating

    NASA Astrophysics Data System (ADS)

    Lee, Kwang Seok; Eom, Deuk Ha; Lee, Jung-Hwan

    2013-03-01

    In this study, the line heating-induced permanent deformation behavior of an SS400 thick plate was investigated through both numerical analysis and experimental testing by applying high-frequency induction heating after generating dual-curvature by secondary line heating. First, an approach based on electromagnetic-thermal-structural coupling numerical analysis was adopted for predicting the temperature distribution and subsequent permanent deformation over the SS400 carbon steel plate. Experimental line heating was also carried out to validate the feasibility of the numerical analysis by applying newly designed laboratory-scale high-frequency (HF) induction-heating (IH) equipment. It was found that the shape of the heat-affected zone (HAZ) generated by HF IH and the subsequent microstructure of the SS400 carbon steel plate within the HAZ were strongly dependent on the input power. Permanent vertical deformation increased with an increase in the input power, regardless of the shape of the doubly curved plates (concave- or saddle-type plates). Transverse curvature determined in both the simulation and the experiment were investigated and compared.

  10. Compressive deformation behavior of CrMnFeCoNi high-entropy alloy

    NASA Astrophysics Data System (ADS)

    Jang, Min Ji; Joo, Soo-Hyun; Tsai, Che-Wei; Yeh, Jien-Wei; Kim, Hyoung Seop

    2016-11-01

    The compressive deformation behavior of a single phase CrMnFeCoNi high-entropy alloy (HEA) is investigated using experimental and theoretical approaches. The equiaxed microstructures are observed using optical microscope, electron backscattered diffraction, and synchrotron X-ray diffraction (XRD) techniques. Compressive results reveal that the CrMnFeCoNi HEA has a high strain-hardening exponent in spite of its large grain size due to increased dislocation density and severe lattice distortion. The compressive texture of the HEA resembles those of typical FCC metals. The phenomenological dislocation-based constitutive model well describes the compressive deformation behavior. The predicted dislocation density is in good quantitative agreement with the experimental value measured using whole-profile fitting of synchrotron XRD peaks. It can be confirmed from the experimental and theoretical findings that the deformation mechanism of the CrMnFeCoNi HEA is the conventional dislocation glide and mechanical twinning is negligible contrary to general belief.

  11. High-rate deformation and fracture of steel 09G2S

    NASA Astrophysics Data System (ADS)

    Balandin, Vl. Vas.; Balandin, Vl. Vl.; Bragov, A. M.; Igumnov, L. A.; Konstantinov, A. Yu.; Lomunov, A. K.

    2014-11-01

    The results of experimental and theoretical studies of steel 09G2S deformation and fracture laws in a wide range of strain rates and temperature variations are given. The dynamic deformation curves and the ultimate characteristics of plasticity in high-rate strain were determined by the Kolsky method in compression, extension, and shear tests. The elastoplastic properties and spall strength were studied by using the gaseous gun of calibre 57 mm and the interferometer VISAR according to the plane-wave experiment technique. The data obtained by the Kolsky method were used to determine the parameters of the Johnson-Cook model which, in the framework of the theory of flow, describes how the yield surface radius depends on the strain, strain rate, and temperature.

  12. High cell-surface density of HER2 deforms cell membranes

    PubMed Central

    Chung, Inhee; Reichelt, Mike; Shao, Lily; Akita, Robert W.; Koeppen, Hartmut; Rangell, Linda; Schaefer, Gabriele; Mellman, Ira; Sliwkowski, Mark X.

    2016-01-01

    Breast cancers (BC) with HER2 overexpression (referred to as HER2 positive) progress more aggressively than those with normal expression. Targeted therapies against HER2 can successfully delay the progression of HER2-positive BC, but details of how this overexpression drives the disease are not fully understood. Using single-molecule biophysical approaches, we discovered a new effect of HER2 overexpression on disease-relevant cell biological changes in these BC. We found HER2 overexpression causes deformation of the cell membranes, and this in turn disrupts epithelial features by perturbing cell–substrate and cell–cell contacts. This membrane deformation does not require receptor signalling activities, but results from the high levels of HER2 on the cell surface. Our finding suggests that early-stage morphological alterations of HER2-positive BC cells during cancer progression can occur in a physical and signalling-independent manner. PMID:27599456

  13. In-process deformation measurements of translucent high speed fibre-reinforced disc rotors

    NASA Astrophysics Data System (ADS)

    Philipp, Katrin; Filippatos, Angelos; Koukourakis, Nektarios; Kuschmierz, Robert; Leithold, Christoph; Langkamp, Albert; Fischer, Andreas; Czarske, Jürgen

    2015-07-01

    The high stiffness to weight ratio of glass fibre-reinforced polymers (GFRP) makes them an attractive material for rotors e.g. in the aerospace industry. We report on recent developments towards non-contact, in-situ deformation measurements with temporal resolution up to 200 µs and micron measurement uncertainty. We determine the starting point of damage evolution inside the rotor material through radial expansion measurements. This leads to a better understanding of dynamic material behaviour regarding damage evolution and the prediction of damage initiation and propagation. The measurements are conducted using a novel multi-sensor system consisting of four laser Doppler distance (LDD) sensors. The LDD sensor, a two-wavelength Mach-Zehnder interferometer was already successfully applied for dynamic deformation measurements at metallic rotors. While translucency of the GFRP rotor material limits the applicability of most optical measurement techniques due to speckles from both surface and volume of the rotor, the LDD profits from speckles and is not disturbed by backscattered laser light from the rotor volume. The LDD sensor evaluates only signals from the rotor surface. The anisotropic glass fibre-reinforcement results in a rotationally asymmetric dynamic deformation. A novel signal processing algorithm is applied for the combination of the single sensor signals to obtain the shape of the investigated rotors. In conclusion, the applied multi-sensor system allows high temporal resolution dynamic deformation measurements. First investigations regarding damage evolution inside GFRP are presented as an important step towards a fundamental understanding of the material behaviour and the prediction of damage initiation and propagation.

  14. Laboratory Studies of High Temperature Deformation and Fracture of Lava Domes

    NASA Astrophysics Data System (ADS)

    Smith, R.; Sammonds, P.; Tuffen, H.; Meredith, P.

    2007-12-01

    The high temperature fracture mechanics of magma at high temperatures exerts a fundamental control on the stability of lava domes and the timing and style of eruptions at andesitic to dacitic volcanoes. This is evidenced in the pervasive fracturing seen in both ancient and active magma conduits and lava domes; in addition to the volcanic earthquakes that occur before and during episodes of dome growth and dome collapse. Uniaxial and triaxial deformation experiments have been performed on crystal rich and crystal free magmas (andesite from Ancestral Mount Shasta, California, USA and a rhyolitic obsidian from Krafla, Iceland) at a range of temperatures (up to 900°C), confining pressures (up to 50 MPa) and strain rates (10-5s-1) to 10-3s-1) whilst recording acoustic emissions (AE). Results from these experiments provide useful inputs into models of lava dome stability, extrusion mechanisms, and source mechanisms for volcanic earthquakes. However, the large sample sizes used to ensure valid results (25mm diameter and 75mm length) made it difficult to maintain stable high temperatures under confined conditions. Also, only rudimentary AE data could be obtained, due to the distance of the transducers from the samples to keep them away from the high temperatures. Here, we present modifications to this apparatus, which include a new furnace, improved loading system, additional pore pressure and permeability measurement capability, and vastly improved acoustic monitoring. This allows (1)stable higher temperatures (up to 1000°C) to be achieved under confined conditions, (2) high temperature and moderate pressure (up to 70 MPa) hydrostatic measurements of permeability and acoustic velocities, (3) high temperature triaxial deformation under different pore fluid and pressure conditions, and (4) full waveform AE monitoring for all deformation experiments. This system can thus be used to measure the physical properties and strength of rocks under volcanic conditions and to

  15. Carbonates in thrust faults: High temperature investigations into deformation processes in calcite-dolomite systems

    NASA Astrophysics Data System (ADS)

    Kushnir, A.; Kennedy, L.; Misra, S.; Benson, P.

    2012-04-01

    The role of dolomite on the strength and evolution of calcite-dolomite fold and thrust belts and nappes (as observed in the Canadian Rockies, the Swiss Alps, the Italian Apennines, and the Naukluft Nappe Complex) is largely unknown. Field investigations indicate that strain in natural systems is localized in calcite, resulting in a ductile response, while dolomite deforms in a dominantly brittle manner. To date, experimental studies on polymineralic carbonate systems are limited to homogeneous, fine-grained, calcite-dolomite composites of relatively low dolomite content. The effect of dolomite on limestone rheology, the onset of crystal-plastic deformation in dolomite in composites, and the potential for strain localization in composites have not yet been fully quantified. Constant displacement rate (3x10-4 s-1and 10-4 s-1), high confining pressure (300 MPa) and high temperature (750° C and 800° C) torsion experiments were conducted to address the role of dolomite on the strength of calcite-dolomite composites. Experiments were performed on samples produced by hot isostatic pressing (HIP) amalgams of a natural, pure dolomite and a reagent, pure calcite. We performed experiments on the following mixtures (given as dolomite%): 25%, 35%, 50%, and 75%. These synthetic HIP products eliminated concerns of mineralogical impurities and textural anomalies due to porosity, structural fabrics (e.g., foliation) and fossil content. The samples were deformed up to a maximum finite shear strain of 5.0 and the experimental set up was unvented to inhibit sample decarbonation. Mechanical data shows a considerable increase in sample yield strength with increasing dolomite content. Experimental products with low starting dolomite content (dol%: 25% and 35%) display macroscopic strain localization along compositionally defined foliation. Experimental products with high dolomite content (dol%: 50% and 75%) demonstrate no macroscopic foliation. Post-deformation microstructure analysis

  16. Crustal deformation dynamics and stress evolution during seamount subduction: High-resolution 3-D numerical modeling

    NASA Astrophysics Data System (ADS)

    Ruh, Jonas B.; Sallarès, Valentí; Ranero, César R.; Gerya, Taras

    2016-09-01

    Seamounts or submarine volcanoes frequently collide with the overriding crust along presently active subduction zones locally modifying stress and permanent deformation patterns. Dynamics of this process is not fully understood, and several end-member scenarios of seamount-crust interaction are proposed. Here we use high-resolution 3-D numerical models to investigate evolution of crustal deformation and stress distribution within the upper plate induced by the underthrusting of subducting seamounts. The dynamical effects of the upper plate strength, subduction interface strength, and strain weakening of the crust are investigated. Experiment results demonstrate that characteristic crustal fracturing patterns formed in response to different seamount-crust interaction scenarios. Indenting seamounts strongly deform the overriding plate along a corridor as wide as the underthrusting seamount by constantly shifting subvertical shear zones rooted at the seamount extensions. A reentrant develops during initial seamount collision. A topographic bulge atop the seamount and lateral ridges emerge from further seamount subduction. Obtained stress pattern shows areas of large overpressure above the rearward and large underpressure above the trenchward flank of the seamount. Results of numerical experiments are consistent with seismic reflection images and seismic velocity models of the upper plate in areas of seamount subduction along the Middle America Trench and give important insights into the long-lasting question, whether subducting seamounts and rough seafloor act as barriers or asperities for megathrust earthquakes.

  17. Integrated experimental and computational studies of deformation of single crystal copper at high strain rates

    NASA Astrophysics Data System (ADS)

    Rawat, S.; Chandra, S.; Chavan, V. M.; Sharma, S.; Warrier, M.; Chaturvedi, S.; Patel, R. J.

    2014-12-01

    Quasi-static (0.0033 s-1) and dynamic (103 s-1) compression experiments were performed on single crystal copper along ⟨100⟩ and ⟨110⟩ directions and best-fit parameters for the Johnson-Cook (JC) material model, which is an important input to hydrodynamic simulations for shock induced fracture, have been obtained. The deformation of single crystal copper along the ⟨110⟩ direction showed high yield strength, more strain hardening, and less strain rate sensitivity as compared to the ⟨100⟩ direction. Although the JC model at the macro-scale is easy to apply and describes a general response of material deformation, it lacks physical mechanisms that describe the influence of texture and initial orientation on the material response. Hence, a crystal plasticity model based on the theory of thermally activated motion of dislocations was used at the meso-scale, in which the evolution equations permit one to study and quantify the influence of initial orientation on the material response. Hardening parameters of the crystal plasticity model show less strain rate sensitivity along the ⟨110⟩ orientation as compared to the ⟨100⟩ orientation, as also shown by the JC model. Since the deformation process is inherently multiscale in nature, the shape changes observed in the experiments due to loading along ⟨100⟩ and ⟨110⟩ directions are also validated by molecular dynamics simulations at the nano-scale.

  18. Quantifying and observing viscoplasticity at the nanoscale: highly localized deformation mechanisms in ultrathin nanocrystalline gold films.

    PubMed

    Hosseinian, Ehsan; Legros, Marc; Pierron, Olivier N

    2016-04-28

    This study unveils the stress relaxation transient deformation mechanisms in 100 nm-thick, nanocrystalline Au films thanks to a robust quantitative in situ TEM MEMS nanomechanical testing approach to quantify stress relaxation and to perform in situ observations of time-dependent deformation in ultrathin nanocrystalline films. The relaxation is characterized by a decrease in plastic strain rate of more than one order of magnitude over the first ∼30 minutes (from 10(-4) to less than 10(-5) s(-1)). For longer relaxation experiments, the plastic strain rate decreases down to 10(-7) s(-1) after several hours. The power-law exponent n, relating plastic strain rate and stress, continuously decreases from initial large values (n from 6 to 14 at t = 0) down to low values (n ∼ 1-2) after several hours. In situ TEM observations reveal that the relaxation behavior is initially accommodated by highly localized, sustained, intergranular and transgranular dislocation motion. Over time, the dislocation sources become less operative or exhausted, leading to a transition to grain-boundary-diffusion based mechanisms. The results also highlight a promising technique for nanoscale characterization of time-dependent deformation.

  19. Constraining the equation of state of nuclear matter with gravitational wave observations: Tidal deformability and tidal disruption

    NASA Astrophysics Data System (ADS)

    Maselli, Andrea; Gualtieri, Leonardo; Ferrari, Valeria

    2013-11-01

    We study how to extract information on the neutron star equation of state from the gravitational wave signal emitted during the coalescence of a binary system composed of two neutron stars or a neutron star and a black hole. We use post-Newtonian templates which include the tidal deformability parameter and, when tidal disruption occurs before merger, a frequency cutoff. Assuming that this signal is detected by Advanced LIGO/Virgo or the Einstein Telescope, we evaluate the uncertainties on these parameters using different data-analysis strategies based on the Fisher matrix approach and on recently obtained analytical fits of the relevant quantities. We find that the tidal deformability is more effective than the stellar compactness to discriminate among different possible equations of state.

  20. Unified description of the double {beta} decay to the first quadrupole phonon state in spherical and deformed nuclei

    SciTech Connect

    Raduta, C. M.; Raduta, A. A.

    2007-10-15

    The Gamow-Teller transition operator is written as a polynomial in the dipole proton-neutron and quadrupole charge-conserving quasiparticle random-phase approximation boson operators, using the prescription of the boson expansion technique. Then, the 2{nu}{beta}{beta} process ending on the first 2{sup +} state in the daughter nucleus is allowed through one-, two-, and three-boson states describing the odd-odd intermediate nucleus. The approach uses a single particle basis that is obtained by projecting out the good angular momentum from an orthogonal set of deformed functions. The basis for mother and daughter nuclei may have different deformations. The GT transition amplitude as well as the half-lives were calculated for 18 transitions. Results are compared with the available data as well as with the predictions obtained with other methods.

  1. Mathematical and computational modeling of a ferrofluid deformable mirror for high-contrast imaging

    NASA Astrophysics Data System (ADS)

    Lemmer, Aaron J.; Griffiths, Ian M.; Groff, Tyler D.; Rousing, Andreas W.; Kasdin, N. Jeremy

    2016-07-01

    Deformable mirrors (DMs) are an enabling and mission-critical technology in any coronagraphic instrument designed to directly image exoplanets. A new ferro fluid deformable mirror technology for high-contrast imaging is currently under development at Princeton, featuring a flexible optical surface manipulated by the local electromagnetic and global hydraulic actuation of a reservoir of ferro fluid. The ferro fluid DM is designed to prioritize high optical surface quality, high-precision/low-stroke actuation, and excellent low-spatial-frequency performance - capabilities that meet the unique demands of high-contrast coronagraphy in a space-based platform. To this end, the ferro-fluid medium continuously supports the DM face sheet, a configuration that eliminates actuator print-through (or, quilting) by decoupling the nominal surface figure from the geometry of the actuator array. The global pressure control allows independent focus actuation. In this paper we describe an analytical model for the quasi-static deformation response of the DM face sheet to both magnetic and pressure actuation. These modeling efforts serve to identify the key design parameters and quantify their contributions to the DM response, model the relationship between actuation commands and DM surface-profile response, and predict performance metrics such as achievable spatial resolution and stroke precision for specific actuator configurations. Our theoretical approach addresses the complexity of the boundary conditions associated with mechanical mounting of the face sheet, and makes use of asymptotic approximations by leveraging the three distinct length scales in the problem - namely, the low-stroke ( nm) actuation, face sheet thickness ( mm), and mirror diameter (cm). In addition to describing the theoretical treatment, we report the progress of computational multi physics simulations which will be useful in improving the model fidelity and in drawing conclusions to improve the design.

  2. Deformation and degradation of polymers in ultra-high-pressure liquid chromatography.

    PubMed

    Uliyanchenko, Elena; van der Wal, Sjoerd; Schoenmakers, Peter J

    2011-09-28

    Ultra-high-pressure liquid chromatography (UHPLC) using columns packed with sub-2 μm particles has great potential for separations of many types of complex samples, including polymers. However, the application of UHPLC for the analysis of polymers meets some fundamental obstacles. Small particles and narrow bore tubing in combination with high pressures generate significant shear and extensional forces in UHPLC systems, which may affect polymer chains. At high stress conditions flexible macromolecules may become extended and eventually the chemical bonds in the molecules can break. Deformation and degradation of macromolecules will affect the peak retention and the peak shape in the chromatogram, which may cause errors in the obtained results (e.g. the calculated molecular-weight distributions). In the present work we explored the limitations of UHPLC for the analysis of polymers. Degradation and deformation of macromolecules were studied by collecting and re-injecting polymer peaks and by off-line two-dimensional liquid chromatography. Polystyrene standards with molecular weight of 4 MDa and larger were found to degrade at UHPLC conditions. However, for most polymers degradation could be avoided by using low linear velocities. No degradation of 3-MDa PS (and smaller) was observed at linear velocities up to 7 mm/s. The column frits were implicated as the main sources of polymer degradation. The extent of degradation was found to depend on the type of the column and on the column history. At high flow rates degradation was observed without a column being installed. We demonstrated that polymer deformation preceded degradation. Stretched polymers eluted from the column in slalom chromatography mode (elution order opposite to that in SEC or HDC). Under certain conditions we observed co-elution of large and small PS molecules though a convolution of slalom chromatography and hydrodynamic chromatography.

  3. Active faults in the deformation zone off Noto Peninsula, Japan, revealed by high- resolution seismic profiles

    NASA Astrophysics Data System (ADS)

    Inoue, T.; Okamura, Y.; Murakami, F.; Kimura, H.; Ikehara, K.

    2008-12-01

    Recently, a lot of earthquakes occur in Japan. The deformation zone which many faults and folds have concentrated exists on the Japan Sea side of Japan. The 2007 Noto Hanto Earthquake (MJMA 6.9) and 2007 Chuetsu-oki Earthquake (MJMA 6.8) were caused by activity of parts of faults in this deformation zone. The Noto Hanto Earthquake occurred on 25 March, 2007 under the northwestern coast of Noto Peninsula, Ishikawa Prefecture, Japan. This earthquake is located in Quaternary deformation zone that is continued from northern margin of Noto Peninsula to southeast direction (Okamura, 2007a). National Institute of Advanced Industrial Science and Technology (AIST) carried out high-resolution seismic survey using Boomer and 12 channels short streamer cable in the northern part off Noto Peninsula, in order to clarify distribution and activities of active faults in the deformation zone. A twelve channels short streamer cable with 2.5 meter channel spacing developed by AIST and private corporation is designed to get high resolution seismic profiles in shallow sea area. The multi-channel system is possible to equip on a small fishing boat, because the data acquisition system is based on PC and the length of the cable is short and easy to handle. Moreover, because the channel spacing is short, this cable is very effective for a high- resolution seismic profiling survey in the shallow sea, and seismic data obtained by multi-channel cable can be improved by velocity analysis and CDP stack. In the northern part off Noto Peninsula, seismic profiles depicting geologic structure up to 100 meters deep under sea floor were obtained. The most remarkable reflection surface recognized in the seismic profiles is erosion surface at the Last Glacial Maximum (LGM). In the western part, sediments about 30 meters (40 msec) thick cover the erosional surface that is distributed under the shelf shallower than 100m in depth and the sediments thin toward offshore and east. Flexures like deformation in

  4. Formation of Nanostructures in Severely Deformed High-Strength Steel Induced by High-Frequency Ultrasonic Impact Treatment

    NASA Astrophysics Data System (ADS)

    Dutta, R. K.; Malet, L.; Gao, H.; Hermans, M. J. M.; Godet, S.; Richardson, I. M.

    2015-02-01

    Surface modification by the generation of a nanostructured surface layer induced via ultrasonic impact treatment was performed at the weld toe of a welded high-strength quenched and tempered structural steel, S690QL1 (Fe-0.16C-0.2Si-0.87Mn-0.33Cr-0.21Mo (wt pct)). Such high-frequency peening techniques are known to improve the fatigue life of welded components. The nanocrystallized structure as a function of depth from the top-treated surface was characterized via a recently developed automated crystal orientation mapping in transmission electron microscopy. Based on the experimental observations, a grain refinement mechanism induced by plastic deformation during the ultrasonic impact treatment is proposed. It involves the formation of low-angle misoriented lamellae displaying a high density of dislocations followed by the subdivision of microbands into blocks and the resulting formation of polygonal submicronic grains. These submicronic grains further breakdown into nano grains. The results show the presence of retained austenite even after severe surface plastic deformation. The average grain size of the retained austenite and martensite is 17 and 35 nm, respectively. The in-grain deformation mechanisms are different in larger and smaller grains. Larger grains show long-range lattice rotations, while smaller grains show plastic deformation through grain rotation. Also the smaller nano grains exhibit the presence of short-range disorder. Surface nanocrystallization also leads to an increased fraction of low angle and low energy coincident site lattice boundaries especially in the smaller grains ( nm).

  5. Deformed lattice states in a Zn{sub 0.9}V{sub 0.1}Se cubic crystal

    SciTech Connect

    Maksimov, V. I. Dubinin, S. F.; Surkova, T. P.; Parkhomenko, V. D.

    2016-01-15

    Neutron scattering patterns have been recorded for a bulk Zn{sub 0.9}V{sub 0.1}Se cubic crystal at room temperature; they are indicative of macroscopic deformation in the material and its significant inhomogeneity. Specific features of the previously found state, preceding the fcc ↔ hcp structural transformation of the sphalerite lattice upon strong destabilization induced by vanadium ions in the doped ZnSe matrix, are discussed taking into account the data obtained.

  6. High-temperature low-cycle fatigue behavior of a NIMONIC PE-16 superalloy—Correlation with deformation and fracture

    NASA Astrophysics Data System (ADS)

    Valsan, M.; Parameswaran, P.; Bhanu Sankara Rao, K.; Vijayalakshmi, M.; Mannan, S. L.; Shastry, D. H.

    1992-06-01

    Low-cycle fatigue (LCF) responses of NIMONIC PE-16 for various prior microstructures and strain amplitudes have been evaluated and the fatigue behavior has been explained in terms of the operative deformation mechanisms. Total strain-controlled LCF tests were performed at 923 K on samples possessing three different prior microstructures: alloy A in solution-annealed condition (free of γ' and carbides), alloy B with double aging treatment (spherical γ' of 18-nm diameter and M23C6), and alloy C with another double aging treatment (γ' of size 35 nm, MC and M23C6). All three microstructures exhibited an intial cyclic hardening followed by a period of gradual softening at 923 K. Coffin-Manson plots describing the plastic strain amplitude vs number of reversals to failure showed that alloy A had maximum fatigue life while C showed the least. Alloy B exhibited a two-slope behavior in the Coffin-Manson plot over the strain amplitudes investigated. This has been ascribed to the change in the degree of homogeneity of deformation at high and low strain amplitudes. Transmission electron microscopic studies were carried out to characterize the various deformation mechanisms and precipitation reactions occurring during fatigue testign. Fresh precipitation of fine γ' was confirmed by the development of “mottled contrast” in alloy C. Evidence for the shearing of the ordered γ' precipitates was revealed by the presence of superdislocations in alloy C. Repeated shearing during cyclic loading led to the reduction in the size of the γ' and consequent softening. Coarser γ' precipitates were associated with Orowan loops. The observed fatigue behavior has been rationalized based on the micromechanisms stated above and on the degree of homogenization of slip assessed by slipband spacing measurements on tested samples.

  7. Deformation of Lawsonite at High Pressure and High Temperature - Implications for Low Velocity Layers in Subduction Zones

    NASA Astrophysics Data System (ADS)

    Amiguet, E.; Hilairet, N.; Wang, Y.; Gillet, P.

    2014-12-01

    During subduction, the hydrated oceanic crust undergoes a series of metamorphic reactions and transform gradually to blueschists and eclogite at depths of 20-50 km. Detailed seismic observations of subduction zones suggest a complex layered structure with the presence of a Low Velocity Layer (LVL) related to the oceanic crust [1] persisting to considerable depths (100- 250 km).While the transformation from blueschist to eclogite [2] and the presence of glaucophane up to 90-100 km [3] could explain some of these observations, the presence of LVL at greater depths could be related to the presence of the hydrous mineral lawsonite (CaAl2(Si2O7)(OH)2 H2O). Its stability field extends to 8.5 GPa and 1100K corresponding to depths up to 250 km in cold hydrous part of subducting slabs [4]. Because these regions undergo large and heterogeneous deformation, lawsonite plasticity and crystal preferred orientation (CPOs) may strongly influence the dynamic of subduction zones and the seismic properties. We present a deformation study at high presssure and high temperature on lawsonite. Six samples were deformed at 4-10 GPa and 600K to 1000K using a D-DIA apparatus [5] at 13-BMD at GSECARS beamline, APS, in axial compression up to 30% deformation with strain rates of 3.10-4s-1 to 6.10-6s-1. We measured in-situ lattice strains (a proxy for macroscopic stress), texture and strain using synchrotron radiations and calculated the macroscopic stress using lawsonite elastic properties [6]. Results from lattice strain analysis show a dependence of flow stress with temperature and strain rate. Texture analysis coupled with transmission electron microscopy showed that dislocation creep is the dominant deformation mechanism under our deformation conditions. [1] Abers, Earth and Planetary Science Letters, 176, 323-330, 2000 [2] Helffrich et al., Journal of Geophysical Research, 94, 753-763, 1989 [3] Bezacier et al., Tectonophysics, 494, 201-210, 2010 [4] Schmidt & Poli, Earth and Planetary

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

    SciTech Connect

    Smirnov, Alexander Ababkov, Nicolay Ozhiganov, Yevgeniy; Popova, Natalya; Zboykova, Nadezhda Koneva, Nina

    2016-01-15

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

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

    NASA Astrophysics Data System (ADS)

    Smirnov, Alexander; Kozlov, Eduard; Ababkov, Nicolay; Popova, Natalya; Nikonenko, Elena; Ozhiganov, Yevgeniy; Zboykova, Nadezhda; Koneva, Nina

    2016-01-01

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

  10. On plane stress state and stress free deformation of thick plate with FGM interface under thermal loading

    NASA Astrophysics Data System (ADS)

    Szubartowski, Damian; Ganczarski, Artur

    2016-10-01

    This paper demonstrates the plane stress state and the stress free thermo-elastic deformation of FGM thick plate under thermal loading. First, the Sneddon-Lockett theorem on the plane stress state in an isotropic infinite thick plate is generalized for a case of FGM problem in which all thermo-mechanical properties are optional functions of depth co-ordinate. The proof is based on application of the Iljushin thermo-elastic potential to displacement type system of equations that reduces it to the plane stress state problem. Then an existence of the purely thermal deformation is proved in two ways: first, it is shown that the unique solution fulfils conditions of simultaneous constant temperature and linear gradation of thermal expansion coefficient, second, proof is based directly on stress type system of equations which straightforwardly reduces to compatibility equations for purely thermal deformation if only stress field is homogeneous in domain and at boundary. Finally, couple examples of application to an engineering problem are presented.

  11. Study on Optimal Grouting Timing for Controlling Uplift Deformation of a Super High Arch Dam

    NASA Astrophysics Data System (ADS)

    Lin, Peng; Zhu, Xiaoxu; Li, Qingbin; Liu, Hongyuan; Yu, Yongjun

    2016-01-01

    A grouting model is developed for use during the grouting of the complex foundation of a super high arch dam. The purpose as to determine the optimal grouting timing and appropriate grouting pressure involved in controlling the uplift deformation of the dam. The model determines the optimal grouting time as the height of the arch dam increases with the concrete pouring, by checking the tensile stresses in the dam against standard specifications. The appropriate grouting pressures are given on the basis of the actual grouting pressures monitored during the upstream riverbed foundation grouting. An engineering procedure, applying the model, was then proposed and used during foundation grouting under the toe block of the Xiluodu super high-arch dam in south-western China. The quality of the foundation grouting was evaluated against the results from pressurized water permeability tests, acoustic wave velocity tests, elastic modulus tests and panoramic photographing of the rockmass on completion of the foundation grouting. The results indicated that the proposed grouting model can be applied to effectively reduce the uplift deformation and associated cracking risk for super high arch dams, and it can be concluded that the proposed engineering grouting procedure is a valuable tool for improving foundation grouting under the toe blocks of a super high arch dam.

  12. Stamping failure analysis of advanced high strength steel sheet based on non-uniform local deformation through thickness

    NASA Astrophysics Data System (ADS)

    Huang, Sheng; Zhao, Yixi; He, Chunfeng

    2013-12-01

    The phenomenon "Shear fracture" is often observed in the stretch-bending process of stamping over small radius with advanced high strength steels (AHSS). It occurs parallel to and near the die radius in the stretch-bending test. Since traditional Forming Limit Diagram (FLD) is unable to describe this type of failure, experimental and simulation works were constructed in this paper to investigate and predict the shear fracture. Fracture experiments were carried out through a stretch-bending test system, and failure mode was observed. There is no obviously thinning at the shear fracture surface. Further research shows that the initial crack of shear fracture occurs at the outer layer of specimen at die radius position. Finite element (FE) models were built for stretch-bending test with 3D element. The non-uniform local deformation through thickness corresponding to bending position was obtained and analyzed. Cockcroft & Latham fracture criterion is used. The outer layer of specimen at bending position reaches the critical fracture state firstly, which agrees well with experiments. Different fracture criteria are also compared and selected to determine this fracture. Results show that based on the non-uniform local deformation, the initial crack location of shear fracture at small radius can be effectively predicted by fracture criteria related to the maximum principle stress.

  13. Engineering of surface microstructure transformations using high rate severe plastic deformation in machining

    NASA Astrophysics Data System (ADS)

    Abolghasem, Sepideh

    research effort, where Large Strain Machining (LSM) is presented as a controlled test of microstructure response. Sample conditions are created using LSM in Face Centered Cubic (FCC) metals, while characterizing the deformation using Digital Image Correlation(DIC) and Infrared(IR) thermography. Microstructural consequences such as grain size, subgrain size and grain boundary responses resulting from the characterized thermomechanical conditions are examined using Electron Back-Scattered Diffraction (EBSD). Once empirical data is generated across the broad thermomechanical conditions, reliable microstructure maps are populated. This characterization can help understand surface microstructures resulting from shear-based manufacturing processes such as turning, milling, shaping, etc. that are created under analogous thermomechanical conditions. Keywords: microstructure characterization, ultrafine grain microstructure, severe plastic deformation, high speed deformation.

  14. A continuum deformation theory for metal-matrix composites at high temperature

    NASA Technical Reports Server (NTRS)

    Robinson, D. N.

    1987-01-01

    A continuum theory is presented for representing the high temperature, time dependent, hereditary deformation behavior of metallic composites that can be idealized as pseudohomogeneous continua with locally definable directional characteristics. Homogenization of textured materials (molecular, granular, fibrous) and applicability of continuum mechanics in structural applications depends on characteristic body dimensions, the severity of gradients (stress, temperature, etc.) in the structure and the relative size of the internal structure (cell size) of the material. The point of view taken here is that the composite is a material in its own right, with its own properties that can be measured and specified for the composite as a whole.

  15. Four-Quasiparticle High-K States in Neutron-Deficient Lead and Polonium Nuclei

    NASA Astrophysics Data System (ADS)

    Shi, Yue; Xu, Furong

    2012-06-01

    Configuration-constrained potential energy surface calculations have been performed to investigate four-quasiparticle high-K configurations in neutron-deficient lead and polonium isotopes. A good agreement between the calculations and the experimental data has been found for the excitation energy of the observed Kπ = 19- state in 188Pb. Several lowly excited high-K states are predicted, and the large oblate deformation and low energy indicate high-K isomerism in these nuclei.

  16. Elastic deformation and area per lipid of membranes: atomistic view from solid-state deuterium NMR spectroscopy.

    PubMed

    Kinnun, Jacob J; Mallikarjunaiah, K J; Petrache, Horia I; Brown, Michael F

    2015-01-01

    This article reviews the application of solid-state ²H nuclear magnetic resonance (NMR) spectroscopy for investigating the deformation of lipid bilayers at the atomistic level. For liquid-crystalline membranes, the average structure is manifested by the segmental order parameters (SCD) of the lipids. Solid-state ²H NMR yields observables directly related to the stress field of the lipid bilayer. The extent to which lipid bilayers are deformed by osmotic pressure is integral to how lipid-protein interactions affect membrane functions. Calculations of the average area per lipid and related structural properties are pertinent to bilayer remodeling and molecular dynamics (MD) simulations of membranes. To establish structural quantities, such as area per lipid and volumetric bilayer thickness, a mean-torque analysis of ²H NMR order parameters is applied. Osmotic stress is introduced by adding polymer solutions or by gravimetric dehydration, which are thermodynamically equivalent. Solid-state NMR studies of lipids under osmotic stress probe membrane interactions involving collective bilayer undulations, order-director fluctuations, and lipid molecular protrusions. Removal of water yields a reduction of the mean area per lipid, with a corresponding increase in volumetric bilayer thickness, by up to 20% in the liquid-crystalline state. Hydrophobic mismatch can shift protein states involving mechanosensation, transport, and molecular recognition by G-protein-coupled receptors. Measurements of the order parameters versus osmotic pressure yield the elastic area compressibility modulus and the corresponding bilayer thickness at an atomistic level. Solid-state ²H NMR thus reveals how membrane deformation can affect protein conformational changes within the stress field of the lipid bilayer.

  17. Origin and deformation of high porosity bands in the Takanoobane Rhyolite lava of Aso volcano, Japan

    NASA Astrophysics Data System (ADS)

    Furukawa, K.; Uno, K.

    2015-10-01

    In rhyolite lavas, the high porosity bands are often developed. They potentially act as pathways for gas movement to the lava surface. Since explosive activities of lavas are generally considered to be controlled by degassing system, understanding the origin and deformation process of the high porosity bands is important to assessing volcanic hazards. The Takanoobane rhyolite lava in the middle of Kyushu Island in SW Japan is effused at 51 ± 5 ka. The volume, flow length, and thickness are 0.14 km3, > 2 km, and about 90 m, respectively. The central crystalline part of the lava is characterized by the light-colored bands defined by the high porosity zone (HPZ). On the basis of geological and petrographical studies, we revealed that the HPZ was primary formed by ductile-brittle tearing of the lava (known as cavitation). According to the AMS results, the HPZs were subsequently stretched and flattened laterally during the concentric spreading of the lava. This deformation process could stretch the HPZ not only radially but also laterally. This effective stretching developed the HPZ into pervasive thin bands. Since the HPZs act as degassing pathways to the lava surface, the pervasive HPZ bands may play a role in providing volcanic gasses to void spaces created in surface fold hinges of rhyolite lavas. Thus, this degassing system may promote explosive activity of the lava surface.

  18. Recrystallization kinetics of an austenitic high-manganese steel subjected to severe plastic deformation

    NASA Astrophysics Data System (ADS)

    Yanushkevich, Zh. Ch.; Molodov, D. A.; Belyakov, A. N.; Kaibyshev, R. O.

    2016-09-01

    The evolution of the microstructure and the properties of an austenitic high-manganese steel subjected to severe deformation by cold rolling and subsequent recrystallization annealing is investigated. Cold rolling is accompanied by mechanical structural twinning and shear banding. The microhardness and microstructural analysis of annealed samples are used to study the recrystallization kinetics of the high-manganese steel. It is shown that large plastic deformation and subsequent annealing result in rapid development of recrystallization processes and the formation of an ultrafine-grained structure. A completely recrystallized structure with an average grain size of 0.64 μm forms after 30-min annealing at a temperature of 550°C. No significant structural changes are observed when the annealing time increases to 18 h, which indicates stability of the recrystallized microstructure. The steel cold rolled to 90% and annealed at 550°C for 30 min demonstrates very high strength properties: the yield strength and the tensile strength achieve 650 and 850MPa, respectively. The dependence of the strength properties of the steel on the grain size formed after rolling and recrystallization annealing is described by the Hall-Petch relation.

  19. The mechanical microenvironment of high concentration agarose for applying deformation to primary chondrocytes.

    PubMed

    Zignego, Donald L; Jutila, Aaron A; Gelbke, Martin K; Gannon, Daniel M; June, Ronald K

    2014-06-27

    Cartilage and chondrocytes experience loading that causes alterations in chondrocyte biological activity. In vivo chondrocytes are surrounded by a pericellular matrix with a stiffness of ~25-200kPa. Understanding the mechanical loading environment of the chondrocyte is of substantial interest for understanding chondrocyte mechanotransduction. The first objective of this study was to analyze the spatial variability of applied mechanical deformations in physiologically stiff agarose on cellular and sub-cellular length scales. Fluorescent microspheres were embedded in physiologically stiff agarose hydrogels. Microsphere positions were measured via confocal microscopy and used to calculate displacement and strain fields as a function of spatial position. The second objective was to assess the feasibility of encapsulating primary human chondrocytes in physiologically stiff agarose. The third objective was to determine if primary human chondrocytes could deform in high-stiffness agarose gels. Primary human chondrocyte viability was assessed using live-dead imaging following 24 and 72h in tissue culture. Chondrocyte shape was measured before and after application of 10% compression. These data indicate that (1) displacement and strain precision are ~1% and 6.5% respectively, (2) high-stiffness agarose gels can maintain primary human chondrocyte viability of >95%, and (3) compression of chondrocytes in 4.5% agarose can induce shape changes indicative of cellular compression. Overall, these results demonstrate the feasibility of using high-concentration agarose for applying in vitro compression to chondrocytes as a model for understanding how chondrocytes respond to in vivo loading.

  20. Mars' rotational state and tidal deformations from radio interferometry of a network of landers.

    NASA Astrophysics Data System (ADS)

    Iess, L.; Giuliani, S.; Dehant, V.

    2012-04-01

    The precise determination of the rotational state of solar system bodies is one of the main tools to investigate their interior structure. Unfortunately the accuracies required for geophysical interpretations are very stringent, and generally unattainable from orbit using optical or radar tracking of surface landmarks. Radio tracking of a lander from ground or from a spacecraft orbiting the planet offers substantial improvements, especially if the lander lifetime is adequately long. The optimal configuration is however attained when two or more landers can be simultaneously tracked from a ground antenna in an interferometric mode. ESA has been considering a network of landers on Mars since many years, and recently this concept has been revived by the study of the Mars Network Science Mission (MNSM). The scientific rationale of MNSM is the investigation of the Mars' interior and atmosphere by means of a network of two or three landers, making it especially suitable for interferometric observations. In order to synthesize an interferometer, the MNSN landers must be tracked simultaneously from a single ground antenna in a coherent two-way mode. The uplink radio signal (at X- or Ka-band) is received by the landers' transponders and retransmitted to ground in the same frequency band. The signals received at ground station are then recorded (typically at few tens of kHz) and beaten against each other to form the output of the interferometer, a complex phasor. The differential phase retain information on Mars' rotational parameters and tidal deformations. A crucial aspect of the interferometric configuration is the rejection of common noise and error sources. Errors in the station location, Earth orientation parameters and ephemerides, path delays due to the Earth troposphere and ionosphere, and, to a good extent, interplanetary plasma are cancelled out. The main residual errors are due to differential path delays from Mars' atmosphere and differential drifts of the

  1. Structural evolution during mechanical deformation in high-barrier PVDF-TFE/PET multilayer films using in situ X-ray techniques.

    PubMed

    Jordan, Alex M; Lenart, William R; Carr, Joel M; Baer, Eric; Korley, Lashanda T J

    2014-03-26

    Poly(vinylidene fluoride-co-tetrafluoroethylene) (PVDF-TFE) is confined between alternating layers of poly(ethylene terephthalate) (PET) utilizing a unique multilayer processing technology, in which PVDF-TFE and PET are melt-processed in a continuous fashion. Postprocessing techniques including biaxial orientation and melt recrystallization were used to tune the crystal orientation of the PVDF-TFE layers, as well as achieve crystallinity in the PET layers through strain-induced crystallization and thermal annealing during the melt recrystallization step. A volume additive model was used to extract the effect of crystal orientation within the PVDF-TFE layers and revealed a significant enhancement in the modulus from 730 MPa in the as-extruded state (isotropic) to 840 MPa in the biaxially oriented state (on-edge) to 2230 MPa in the melt-recrystallized state (in-plane). Subsequently, in situ wide-angle X-ray scattering was used to observe the crystal structure evolution during uniaxial deformation in both the as-extruded and melt-recrystallized states. It is observed that the low-temperature ferroelectric PVDF-TFE crystal phase in the as-extruded state exhibits equatorial sharpening of the 110 and 200 crystal peaks during deformation, quantified using the Hermans orientation function, while in the melt-recrystallized state, an overall increase in the crystallinity occurs during deformation. Thus, we correlated the mechanical response (strain hardening) of the films to these respective evolved crystal structures and highlighted the ability to tailor mechanical response. With a better understanding of the structural evolution during deformation, it is possible to more fully characterize the structural response to handling during use of the high-barrier PVDF-TFE/PET multilayer films as commercial dielectrics and packaging materials.

  2. High-charge-state ion sources

    SciTech Connect

    Clark, D.J.

    1983-06-01

    Sources of high charge state positive ions have uses in a variety of research fields. For heavy ion particle accelerators higher charge state particles give greater acceleration per gap and greater bending strength in a magnet. Thus higher energies can be obtained from circular accelerators of a given size, and linear accelerators can be designed with higher energy gain per length using higher charge state ions. In atomic physics the many atomic transitions in highly charged ions supplies a wealth of spectroscopy data. High charge state ion beams are also used for charge exchange and crossed beam experiments. High charge state ion sources are reviewed. (WHK)

  3. In-situ neutron diffraction study of deformation behavior of a multi-component high-entropy alloy

    SciTech Connect

    Wu, Y.; Liu, W. H.; He, Z. B.; Lu, Z. P.; Wang, X. L.; Ma, D.; Stoica, A. D.; Nieh, T. G.

    2014-02-03

    Deformation behavior of a high-entropy alloy (HEA) was investigated by in situ tensile deformation with neutron diffraction. It was found that the face-centered cubic (FCC) HEA alloy showed strong crystal elastic and plastic anisotropy, and the evolution of its lattice strains and textures were similar to those observed in conventional FCC metals and alloys. Our results demonstrated that, in spite of chemical complexity, the multi-component HEA behaved like a simple FCC metal and the deformation was caused by the motion of mixed dislocations.

  4. In situ neutron diffraction study of deformation behavior of a multi-component high-entropy alloy

    SciTech Connect

    Wu, Yuan; Liu, W H; Wang, Prof Xun-Li; Ma, Dong; Stoica, Alexandru Dan; Nieh, T. G.; He, Z b; Lu, Z.P.

    2014-01-01

    Deformation behavior of a high-entropy alloy (HEA) was investigated by in situ tensile deformation with neutron diffraction. It was found that the face-centered cubic (FCC) HEA alloy showed strong crystal elastic and plastic anisotropy, and the evolution of its lattice strains and textures were similar to those observed in conventional FCC metals and alloys. Our results demonstrated that, in spite of chemical complexity, the multi-component HEA behaved like a simple FCC metal and the deformation was caused by the motion of mixed dislocations.

  5. In-situ neutron diffraction study of deformation behavior of a multi-component high-entropy alloy

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Liu, W. H.; Wang, X. L.; Ma, D.; Stoica, A. D.; Nieh, T. G.; He, Z. B.; Lu, Z. P.

    2014-02-01

    Deformation behavior of a high-entropy alloy (HEA) was investigated by in situ tensile deformation with neutron diffraction. It was found that the face-centered cubic (FCC) HEA alloy showed strong crystal elastic and plastic anisotropy, and the evolution of its lattice strains and textures were similar to those observed in conventional FCC metals and alloys. Our results demonstrated that, in spite of chemical complexity, the multi-component HEA behaved like a simple FCC metal and the deformation was caused by the motion of mixed dislocations.

  6. Occurrence of oral deformities in larval anurans

    USGS Publications Warehouse

    Drake, D.L.; Altig, R.; Grace, J.B.; Walls, S.C.

    2007-01-01

    We quantified deformities in the marginal papillae, tooth rows, and jaw sheaths of tadpoles from 13 population samples representing three families and 11 sites in the southeastern United States. Oral deformities were observed in all samples and in 13.5-98% of the specimens per sample. Batrachochytrium dendrobatidis (chytrid) infections were detected in three samples. There was high variability among samples in the pattern and number of discovered deformities. Pairwise associations between oral structures containing deformities were nonrandom for several populations, especially those with B. dendrobatidis infections or high total numbers of deformities. Comparisons of deformities among samples using multivariate analyses revealed that tadpole samples grouped together by family. Analyses of ordination indicated that three variables, the number of deformities, the number of significant associations among deformity types within populations, and whether populations were infected with B. dendrobatidis, were significantly correlated with the pattern of deformities. Our data indicate that the incidence of oral deformities can be high in natural populations and that phylogeny and B. dendrobatidis infection exert a strong influence on the occurrence and type of oral deformities in tadpoles. ?? by the American Society of Ichthyologists and Herperologists.

  7. Evolving Stress State and Deformation Mechanism in the Himalayan Foreland Fold-and-Thrust Belt, Northern Pakistan

    NASA Astrophysics Data System (ADS)

    Ahmad, I.; Dasti, N.

    2010-12-01

    Crustal deformation along with shortening due to northward under-thrusting of the Indian plate beneath the Eurasian plate continues to create active tectonic features on the northern fringes of the Indian craton since major collision began in the Eocene. Here the study provides insights on the evolving stress state and deformation mechanism of the Salt Range and Potwar area of Northern Pakistan. This part of Himalayan foreland fold-and-thrust-belt has severe history of deformation during 5.1 Ma and 2 Ma. This foreland area lies between Main Boundary Thrust (MBT) in the north, Himalayan Frontal Thrust (HFT) in the south and Jhelum fault of sinistral nature in the east & Kalabagh fault of dextral nature in the west. An integrated data from seismic reflection profiles and drilling logs reveal that the subsurface deformation encompasses pop-ups, imbricates, duplexes with in-sequence and out-of-sequence thrusting. It also depicts that intensity of deformation increases from the northern margin of Soan geosyncline towards north due to lacking of evaporites while in the south it decreases due to gradual increase in salt thickness. Surface geologic mapping glimpses a series of thrust sheets and anticlines trending ENE-SWS in the eastern and central part of the study area; whereas in the western part, the trend is almost E-W. This variation in the trend of structures is the result of counter clock rotational behaviour (~10°deviation from north to the west) of north-western part of the Indian lithospheric plate. Current outcrop-scale natural fracture data collected from selected anticlinal structures of the study area is presented to manifest the stress evolution and deformation styles under the established tectonic framework. Collected data is analysed for the evaluation of tectonic stress direction and deformation mechanism. The genetic arrangement and types of fractures observed in the study area indicate that the whole area is under compression. The data also testify

  8. Pinning, flow and plastic deformation of flux vortices in high T(sub c) superconductors

    NASA Technical Reports Server (NTRS)

    Roytburd, A.

    1990-01-01

    In high temperature superconductor (HTSC) materials the vortices are highly mobile and flexible. This is reflected in different models of melt of a vortex lattice. Another aspect of the problem is stressed: an easy nucleation and high mobility of dislocations in the vortex lattice. Some models of plastic deformation of vortex lattice are considered as a result of its interaction with a real crystal structure. Depinning is interpreted as yield of plastic flow is vortex medium. Effect of macroscopic defects in crystal structures (pores, inclusions, grain and domain boundaries) is being considered in detail. Available experimental facts on magnetization and a critical current in HTSC and conventional superconductors are discussed from the points of view of depinning to vortices vs. plastic flow of vortices vs. plastic flow of vortices medium.

  9. Deformation and failure of OFHC copper under high strain rate shear compression

    NASA Astrophysics Data System (ADS)

    Ruggiero, Andrew; Testa, Gabriel; Bonora, Nicola; Iannitti, Gianluca; Persechino, Italo; Colliander, Magnus Hörnqvist

    2017-01-01

    Hat-shaped specimen geometries were developed to generate high strain, high-strain-rates deformation under prescribed conditions. These geometries offer also the possibility to investigate the occurrence of ductile rupture under low or negative stress triaxiality, where most failure models fail. In this work, three tophat geometries were designed, by means of extensive numerical simulation, to obtain desired stress triaxiality values within the shear region that develops across the ligament. Material failure was simulated using the Continuum Damage Model (CDM) formulation with a unilateral condition for damage accumulation and validated by comparing with quasi-static and high strain rate compression tests results on OFHC copper. Preliminary results seem to indicate that ductile tearing initiates at the specimen corner location where positive stress triaxiality occurs because of local rotation and eventually propagates along the ligament.

  10. Magneto-induced large deformation and high-damping performance of a magnetorheological plastomer

    NASA Astrophysics Data System (ADS)

    Liu, Taixiang; Gong, Xinglong; Xu, Yangguang; Pang, Haoming; Xuan, Shouhu

    2014-10-01

    A magnetorheological plastomer (MRP) is a new kind of soft magneto-sensitive polymeric composite. This work reports on the large magneto-deforming effect and high magneto-damping performance of MRPs under a quasi-statical shearing condition. We demonstrate that an MRP possesses a magnetically sensitive malleability, and its magneto-mechanical behavior can be analytically described by the magneto-enhanced Bingham fluid-like model. The magneto-induced axial stress, which drives the deformation of the MRP with 70 wt % carbonyl iron powder, can be tuned in a large range from nearly 0.0 kPa to 55.4 kPa by an external 662.6 kA m-1 magnetic field. The damping performance of an MRP has a significant correlation with the magnetic strength, shear rate, carbonyl iron content and shear strain amplitude. For an MRP with 60 wt % carbonyl iron powder, the relative magneto-enhanced damping effect can reach as high as 716.2% under a quasi-statically shearing condition. Furthermore, the related physical mechanism is proposed, and we reveal that the magneto-induced, particle-assembled microstructure directs the magneto-mechanical behavior of the MRP.

  11. Output-based mesh adaptation for high order Navier-Stokes simulations on deformable domains

    NASA Astrophysics Data System (ADS)

    Kast, Steven M.; Fidkowski, Krzysztof J.

    2013-11-01

    We present an output-based mesh adaptation strategy for Navier-Stokes simulations on deforming domains. The equations are solved with an arbitrary Lagrangian-Eulerian (ALE) approach, using a discontinuous Galerkin finite-element discretization in both space and time. Discrete unsteady adjoint solutions, derived for both the state and the geometric conservation law, provide output error estimates and drive adaptation of the space-time mesh. Spatial adaptation consists of dynamic order increment or decrement on a fixed tessellation of the domain, while a combination of coarsening and refinement is used to provide an efficient time step distribution. Results from compressible Navier-Stokes simulations in both two and three dimensions demonstrate the accuracy and efficiency of the proposed approach. In particular, the method is shown to outperform other common adaptation strategies, which, while sometimes adequate for static problems, struggle in the presence of mesh motion.

  12. Experimental Study of the Deformation of Synthetic White Mica Polycrystalline Aggregates at High Pressure and Temperature

    NASA Astrophysics Data System (ADS)

    Mariani, E.; Rutter, E. H.; Brodie, K. H.; Bystricky, M.; Burlini, L.

    2001-12-01

    White mica is one of the major constituents of metamorphic rocks. Phyllosilicate-bearing rocks play an important role in localizing deformation in the upper to middle crust. Most experimental studies carried out on micas have focused on understanding deformation mechanisms of dark micas and multiphase aggregates, while only a few experiments have been performed on white micas. To investigate the rheology of synthetic white mica polycrystalline aggregates (30μ m grain size), triaxial compaction and compression tests were performed at 200MPa confining pressure, up to 100MPa pore water pressure and at temperatures between 773K and 973K. Torsion experiments were carried out in a Paterson gas rig at 300MPa confining pressure and 973K. Compaction tests showed that higher temperatures and pore water pressures enhanced compaction, leading to a final porosity of < 2%. Neither static recrystallization nor breakdown reactions were observed. Samples sheared in compression between sliders at 973K and strain rates of 5x10-4s-1 and 1x10-4s-1 yielded at 60MPa and 65MPa shear stress respectively, appearing to be stronger at lower strain rates. All shear stress-shear strain curves are characterized by strain-hardening. The stress relaxation technique allowed investigation of strain rates down to 8x10-7s-1. Three experiments were performed in torsion at shear strain rate between 6.7x10-4s-1 and 6.9x10-5s-1 and shear strain γ < 7, in the absence of pore water pressure. Two samples were vented, while the third was unvented. Quasi steady state was reached for γ > 2. The unvented sample was the weakest, yielding at 30MPa shear stress. It showed strain softening before approaching steady state. Optical analysis of the microstructure shows an incipient schistosity forming at 45° to the pre-existing horizontal cleavage planes. Large recrystallized grains seem to be associated with the new schistosity.

  13. Cyclic Deformation Behavior of Fe-18Cr-18Mn-0.63N Nickel-Free High-Nitrogen Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Shao, C. W.; Shi, F.; Li, X. W.

    2015-04-01

    Cyclic deformation and damage behavior of a Ni-free high-nitrogen austenitic stainless steel with a composition of Fe-18Cr-18Mn-0.63N (weight pct) were studied, and the internal stress and effective stress were estimated by partitioning the hysteresis loop during cyclic straining at total strain amplitudes ranging from 3.0 × 10-3 to 1.0 × 10-2. It is found that immediate cyclic softening takes place at all strain amplitudes and subsequently a saturation or quasi-saturation state develops and occupies the main part of the whole fatigue life. The internal stress increases with increasing strain amplitude, while the variation of effective stress with strain amplitude is somewhat complicated. Such a phenomenon is discussed in terms of dislocation structures and the short-range ordering caused by the interaction between nitrogen atoms and substitutional atoms. The relationship of fatigue life vs plastic strain amplitude ( N f-Δ ɛ pl/2) follows a bilinear Coffin-Manson rule, resulting from the variation in slip deformation mode with the applied strain amplitude. At the low strain amplitude, cracks initiate along slip bands, and planar slip dislocation configurations dominate the major characteristic of internal microstructures. At high strain amplitudes, intergranular (mostly along grain boundaries and few along twin boundaries) cracks are generally found, and the deformation microstructures are mainly composed of dislocation cells, stacking faults and a small amount of deformation twins, in addition to planar slip dislocation structures.

  14. High temperature and deformation field measurements at the vicinity of dynamically growing shear bands

    SciTech Connect

    Rosakis, A.J.; Ravichandran, G.; Zhou, M.

    1995-12-31

    The phenomenon of dynamic initiation and propagation of adiabatic shear bands is experimentally and numerically investigated. Pre-notched metal plates are subjected to asymmetric impact load histories (dynamic mode-II loading). Dynamic shear bands emanate from the notch tip and propagate rapidly in a direction nearly parallel to the direction of the impact. Real time temperature histories along a line intersecting and perpendicular to the shear band paths are recorded by means of a high-speed infrared detector system. The materials studied are C-300 (a maraging steel) and Ti - 6 Al - 4 V alloy. Experiments show that the peak temperatures inside the propagating shear bands are approaching 90% of the melting point for C-300 and are significantly lower for the titanium alloy (up to 600{degrees}C). Additionally, measured distances of shear band propagation indicate stronger resistance to shear banding by the Ti - 6Al - 4V alloy. Deformation fields around the propagating shear bands are recorded using high-speed photography. Shear band speeds are found to strongly depend on impact velocities, and are as high as 1200 m/s for C-300 steels. Finite Element simulations of the experiments are carried out under the context of plane strain, considering finite deformations, inertia, heat conduction, thermal softening, strain hardening and strain-rate hardening. In the simulations, the shear band propagation is assumed to be governed by a critical plastic strain criterion. The results are compared with experimental measurements obtained using the high-speed infrared detectors and high-speed photography.

  15. Interplay of collective and single-particle properties of excited states of deformable odd nuclei {sup 155}Eu and {sup 161}Tm

    SciTech Connect

    Sharipov, Sh.; Ermamatov, M. J. Bayimbetova, J. K.

    2008-02-15

    The properties of excited states of two deformable odd nuclei are investigated within the nonadiabatic model previously developed by the present authors. The results of relevant calculations are compared with available experimental data.

  16. Coexistence of spherical states with deformed and superdeformed bands in doubly magic {sup 40}Ca: A shell-model challenge

    SciTech Connect

    Caurier, E.; Nowacki, F.

    2007-05-15

    Large-scale shell-model calculations, with dimensions reaching 10{sup 9}, are carried out to describe the recently observed deformed (ND) and superdeformed (SD) bands based on the first and second excited 0{sup +} states of {sup 40}Ca at 3.35 and 5.21 MeV, respectively. A valence space comprising two major oscillator shells, sd and pf, can accommodate most of the relevant degrees of freedom of this problem. The ND band is dominated by configurations with four particles promoted to the pf shell (4p-4h in short). The SD band by 8p-8h configurations. The ground state of {sup 40}Ca is strongly correlated, but the closed shell still amounts to 65%. The energies of the bands are very well reproduced by the calculations. The out-band transitions connecting the SD band with other states are very small and depend on the details of the mixing among the different np-nh configurations; in spite of that, the calculation describes them reasonably. For the in-band transition probabilities along the SD band, we predict a fairly constant transition quadrupole moment Q{sub 0}(t){approx}170 e fm{sup 2} up to J=10 that decreases toward the higher spins. We submit also that the J=8 states of the deformed and superdeformed bands are maximally mixed.

  17. High Deformability and Particle Size Distribution of Monodisperse Phytoglycogen Nanoparticles Revealed By Atomic Force Microscopy Imaging

    NASA Astrophysics Data System (ADS)

    Baylis, Benjamin; Dutcher, John

    We have used atomic force microscopy (AFM) imaging in water to determine the volume of hydrated monodisperse phytoglycogen nanoparticles adsorbed onto mica surfaces. By significantly reducing the interaction between the AFM tip and the ``sticky'' nanoparticles, we were able to obtain high quality images. We found that the adsorbed particles are highly deformed, forming pancake-like objects on the hydrophilic mica surface. By measuring the distribution of particle volumes, we calculated the average effective spherical radius of the hydrated particles, and compared this value with that measured in solution using small angle neutron scattering. These measurements illustrate the distinct advantages of AFM imaging over other imaging techniques, namely the ability to measure the height of objects in a liquid environment.

  18. On the response of Escherichia coli to high rates of deformation

    NASA Astrophysics Data System (ADS)

    Fitzmaurice, B. C.; Painter, J. D.; Appleby-Thomas, G. J.; Wood, D. C.; Hazael, R.; McMillan, P. F.

    2017-01-01

    While a large body of work exists on the low strain-rate loading of biological systems such as bacteria, there is a paucity of information on the response of such organisms at high rates of deformation. Here, the response of a readily accessible strain of bacteria, Escherichia coli (E. coli), has been examined under shock loading conditions. Although previous studies have shown greatly reduced growth in shock conditions up to several GPa, relationships between loading conditions and bacterial response have yet to be fully elucidated. Initial results of a more rigorous investigation into the 1D shock loading response of E. coli are presented here, expectantly leading to a more comprehensive view of its behaviour when exposed to high pressures. Comparison has been drawn to provide insight into the importance of the nature of the loading regime to the survival of these biological systems.

  19. High-Resolution Seismic Imaging of Quaternary Faults and Deformation in the Los Angeles Region

    NASA Astrophysics Data System (ADS)

    Stephenson, W. J.; Odum, J. K.; Williams, R. A.; Pratt, T. L.; Dolan, J.; Shaw, J. H.

    2001-12-01

    We present results from several P-wave high-resolution seismic imaging studies in the Los Angeles region that characterize Quaternary fault activity and associated deformation. From high-resolution seismic reflection data, we seek crucial information on shallow basin geometry as well as near-surface fault geometry, displacement, slip rates, and timing of Quaternary deformation. Data acquired along a profile in Sherman Oaks reveal a geologic structure in the upper 600 m that contributed to the increased earthquake ground shaking in the high-damage areas south of and along the Los Angeles River resulting from the 1994 Northridge earthquake. A shallow sub-basin imaged on the Sherman Oaks line correlates with an area that experienced greater earthquake damage from possible geometric focussing effects. Finite-difference modeling of the imaged structural geometry along the profile suggests that a peak horizontal-velocity amplification factor of two-and-greater, as well as spatial variability, can be explained in the high-damage area by the sub-basin. High-resolution seismic reflection data acquired across the Santa Monica fault confirm the location of the fault and link related shallow strike-slip faults seen in a nearby trench to deeper structures previously observed in regional studies. The high-resolution seismic data image deformation as shallow as 15 m depth and show the Santa Monica fault dips about 30 degrees north in the upper 300 m. These data, combined with soil age estimates from the trench, yield a reverse-slip rate for the fault of about 0.5 mm/yr. The Puente Hills thrust fault is one of the major faults underlying the urban Los Angeles Basin. Industry-scale and high-resolution seismic reflection images define the location and geometry of active folds above the Puente Hills thrust fault. Four seismic profiles acquired at two locations delineate fold geometry above the thrust. At one of these sites we image an active synclinal axial surface with strata

  20. Investigation of deformation twinning under complex stress states in a rolled magnesium alloy

    SciTech Connect

    Wu, Wei; Chuang, Chih-Pin; Qiao, Dongxiao; Ren, Yang; An, Ke

    2016-05-15

    We employed a specially designed semi-circular notch specimen in the current study to generate the various strain conditions, including uniaxial, biaxial, shear, and plane strains, which was utilized to explore the evolution of different deformation twinning systems under complex loading conditions. We found that when using in situ synchrotron X-ray diffraction mapping method, that the extensive double twins were activated during loading, while nearly no extension twinning activity was detected. After the formation of {10.1} and {10.3} compression twins, they transformed into {10.1}-{10.2} and {10.3}-{10.2} double twins instantaneously at the early stage of deformation. The lattice strain evolutions in different hkls were mapped at selected load levels during the loading-unloading sequence. Finally, the relationship between the macroscopic straining and microscopic response was established.

  1. Investigation of deformation twinning under complex stress states in a rolled magnesium alloy

    DOE PAGES

    Wu, Wei; Chuang, Chih-Pin; Qiao, Dongxiao; ...

    2016-05-15

    We employed a specially designed semi-circular notch specimen in the current study to generate the various strain conditions, including uniaxial, biaxial, shear, and plane strains, which was utilized to explore the evolution of different deformation twinning systems under complex loading conditions. We found that when using in situ synchrotron X-ray diffraction mapping method, that the extensive double twins were activated during loading, while nearly no extension twinning activity was detected. After the formation of {10.1} and {10.3} compression twins, they transformed into {10.1}-{10.2} and {10.3}-{10.2} double twins instantaneously at the early stage of deformation. The lattice strain evolutions in differentmore » hkls were mapped at selected load levels during the loading-unloading sequence. Finally, the relationship between the macroscopic straining and microscopic response was established.« less

  2. Deformation of Cases in High Capacitance Value Wet Tantalum Capacitors under Environmental Stresses

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2016-01-01

    Internal gas pressure in hermetic wet tantalum capacitors is created by air, electrolyte vapor, and gas generated by electrochemical reactions at the electrodes. This pressure increases substantially with temperature and time of operation due to excessive leakage currents. Deformation of the case occurs when the internal pressure exceeds pressure of the environments and can raise significantly when a part operates in space. Contrary to the cylinder case wet tantalum capacitors that have external sealing by welding and internal sealing provided by the Teflon bushing and crimping of the case, no reliable internal sealing exists in the button case capacitors. Single seal design capacitors are used for high capacitance value wet tantalum capacitors manufactured per DLA L&M drawings #04003, 04005, and 10011, and require additional analysis to assure their reliable application in space systems. In this work, leakage currents and case deformation of button case capacitors were measured during different environmental test conditions. Recommendations for derating, screening and qualification testing are given. This work is a continuation of a series of NEPP reports related to quality and reliability of wet tantalum capacitors.

  3. High-temperature deformation and failure of an orthorhombic titanium aluminide sheet material

    SciTech Connect

    Nicolaou, P.D.; Semiatin, S.L.

    1996-11-01

    The high-temperature deformation and failure behavior of an orthorhombic titanium aluminide sheet alloy (fabricated by diffusion bonding of six thin foils) was established by conducting uniaxial tension and plane-strain compression tests at 980 C and strain rates between 10{sup {minus}4} and 10{sup {minus}2} s{sup {minus}1}. The stress-strain response was characterized by a peak stress at low strains followed by moderate flow softening. Values of the strain-rate sensitivity index (m) were between 0.10 and 0.32, and the plastic anisotropy parameter (R) was of the order of 0.6 to 1.0. Cavity nucleation and growth were observed during tensile deformation at strain rates of 10{sup {minus}3} s{sup {minus}1} and higher. However, the combined effects of low m, low cavity growth rate {eta}, and flow softening were deduced to be the source of failure controlled by necking and flow localization rather than cavitation-induced fracture prior to necking.

  4. Extracellular Forces Cause the Nucleus to Deform in a Highly Controlled Anisotropic Manner

    PubMed Central

    Haase, Kristina; Macadangdang, Joan K. L.; Edrington, Claire H.; Cuerrier, Charles M.; Hadjiantoniou, Sebastian; Harden, James L.; Skerjanc, Ilona S.; Pelling, Andrew E.

    2016-01-01

    Physical forces arising in the extra-cellular environment have a profound impact on cell fate and gene regulation; however the underlying biophysical mechanisms that control this sensitivity remain elusive. It is hypothesized that gene expression may be influenced by the physical deformation of the nucleus in response to force. Here, using 3T3s as a model, we demonstrate that extra-cellular forces cause cell nuclei to rapidly deform (<1 s) preferentially along their shorter nuclear axis, in an anisotropic manner. Nuclear anisotropy is shown to be regulated by the cytoskeleton within intact cells, with actin and microtubules resistant to orthonormal strains. Importantly, nuclear anisotropy is intrinsic, and observed in isolated nuclei. The sensitivity of this behaviour is influenced by chromatin organization and lamin-A expression. An anisotropic response to force was also highly conserved amongst an array of examined nuclei from differentiated and undifferentiated cell types. Although the functional purpose of this conserved material property remains elusive, it may provide a mechanism through which mechanical cues in the microenvironment are rapidly transmitted to the genome. PMID:26892269

  5. Extracellular Forces Cause the Nucleus to Deform in a Highly Controlled Anisotropic Manner

    NASA Astrophysics Data System (ADS)

    Haase, Kristina; Macadangdang, Joan K. L.; Edrington, Claire H.; Cuerrier, Charles M.; Hadjiantoniou, Sebastian; Harden, James L.; Skerjanc, Ilona S.; Pelling, Andrew E.

    2016-02-01

    Physical forces arising in the extra-cellular environment have a profound impact on cell fate and gene regulation; however the underlying biophysical mechanisms that control this sensitivity remain elusive. It is hypothesized that gene expression may be influenced by the physical deformation of the nucleus in response to force. Here, using 3T3s as a model, we demonstrate that extra-cellular forces cause cell nuclei to rapidly deform (<1 s) preferentially along their shorter nuclear axis, in an anisotropic manner. Nuclear anisotropy is shown to be regulated by the cytoskeleton within intact cells, with actin and microtubules resistant to orthonormal strains. Importantly, nuclear anisotropy is intrinsic, and observed in isolated nuclei. The sensitivity of this behaviour is influenced by chromatin organization and lamin-A expression. An anisotropic response to force was also highly conserved amongst an array of examined nuclei from differentiated and undifferentiated cell types. Although the functional purpose of this conserved material property remains elusive, it may provide a mechanism through which mechanical cues in the microenvironment are rapidly transmitted to the genome.

  6. [Deformations of the vertebral column in the visually impaired schoolchildren presenting with complicated high myopia and the possibilities for its correction].

    PubMed

    Egorova, T S; Smirnova, T S; Romashin, O V; Egorova, I V

    2016-01-01

    Complicated high myopia is one of the leading causes responsible for the disablement in the children associated with visual impairment especially when it is combined with other pathological conditions and abnormalities among which are disorders of the musculoskeletal system. In the present study, we for the first time examined visually impaired schoolchildren (n=44) who suffered from high myopia complications making use of the computed optical topographer for the evaluation of the state of their vertebral column. The control group consisted of 60 children attending a secondary school. The study revealed various deformations of the musculoskeletal system including scoliosis, misalignment of the pelvis, kyphosis, hyperlordosis, torsion, platypodia, deformation of the lower extremities and the chest. These deformations were more pronounced in the visually impaired schoolchildren in comparison with the children of the same age comprising the control group (p<0,05). It is concluded that the assessment of the state of the vertebral column with the use of the apparatus yields an important information for the elaboration and application of a series of measures for the timely provision of medical assistance needed for the comprehensive rehabilitation of the visually impaired schoolchildren presenting with high myopia complications.

  7. A GPU based high-resolution multilevel biomechanical head and neck model for validating deformable image registration

    SciTech Connect

    Neylon, J. Qi, X.; Sheng, K.; Low, D. A.; Kupelian, P.; Santhanam, A.; Staton, R.; Pukala, J.; Manon, R.

    2015-01-15

    Purpose: Validating the usage of deformable image registration (DIR) for daily patient positioning is critical for adaptive radiotherapy (RT) applications pertaining to head and neck (HN) radiotherapy. The authors present a methodology for generating biomechanically realistic ground-truth data for validating DIR algorithms for HN anatomy by (a) developing a high-resolution deformable biomechanical HN model from a planning CT, (b) simulating deformations for a range of interfraction posture changes and physiological regression, and (c) generating subsequent CT images representing the deformed anatomy. Methods: The biomechanical model was developed using HN kVCT datasets and the corresponding structure contours. The voxels inside a given 3D contour boundary were clustered using a graphics processing unit (GPU) based algorithm that accounted for inconsistencies and gaps in the boundary to form a volumetric structure. While the bony anatomy was modeled as rigid body, the muscle and soft tissue structures were modeled as mass–spring-damper models with elastic material properties that corresponded to the underlying contoured anatomies. Within a given muscle structure, the voxels were classified using a uniform grid and a normalized mass was assigned to each voxel based on its Hounsfield number. The soft tissue deformation for a given skeletal actuation was performed using an implicit Euler integration with each iteration split into two substeps: one for the muscle structures and the other for the remaining soft tissues. Posture changes were simulated by articulating the skeletal structure and enabling the soft structures to deform accordingly. Physiological changes representing tumor regression were simulated by reducing the target volume and enabling the surrounding soft structures to deform accordingly. Finally, the authors also discuss a new approach to generate kVCT images representing the deformed anatomy that accounts for gaps and antialiasing artifacts that may

  8. Dynamic tensile deformation and fracture of a highly particle-filled composite using SHPB and high-speed DIC method

    NASA Astrophysics Data System (ADS)

    Zhou, Z.; Chen, P.; Guo, B.; Huang, F.

    2012-08-01

    In this work, various tensile tests, including Brazilian disc test (BDT), flattened Brazilian disc (FBD) test and semi-circular bending (SCB) test, were carried out on a highly particle-filled composite by using a split Hopkinson pressure bar (SHPB). With the consideration of low strength and low wave impedance of the materials, a quartz crystal transducer was embedded in SHPB to measure the loading forces. A high-speed camera was used to capture the deformation and fracture process of materials. Digital image correlation (DIC) method was used to process these digital images to obtain the dynamic deformation information. Based on the measured strain fields, the crack growth path was determined and the failure mechanism of samples was analyzed. Combining SHPB and DIC method, the indirect tensile stress strain plots of disc samples were obtained, and the dynamic fracture toughness of materials was measured using both FBD and SCB tests. The results show that the tensile failure strength and fracture toughness increases with the increase of strain rates, exhibiting strain rate dependence. The high-speed DIC method combined with SHPB is effective to study the dynamic tensile behaviour of brittle materials with low strengths.

  9. Control of Precambrian basement deformation zones on emplacement of the Laramide Boulder batholith and Butte mining district, Montana, United States

    USGS Publications Warehouse

    Berger, Byron R.; Hildenbrand, Thomas G.; O'Neill, J. Michael

    2011-01-01

    What are the roles of deep Precambrian basement deformation zones in the localization of subsequent shallow-crustal deformation zones and magmas? The Paleoproterozoic Great Falls tectonic zone and its included Boulder batholith (Montana, United States) provide an opportunity to examine the importance of inherited deformation fabrics in batholith emplacement and the localization of magmatic-hydrothermal mineral deposits. Northeast-trending deformation fabrics predominate in the Great Falls tectonic zone, which formed during the suturing of Paleoproterozoic and Archean cratonic masses approximately 1,800 mega-annum (Ma). Subsequent Mesoproterozoic to Neoproterozoic deformation fabrics trend northwest. Following Paleozoic through Early Cretaceous sedimentation, a Late Cretaceous fold-and-thrust belt with associated strike-slip faulting developed across the region, wherein some Proterozoic faults localized thrust faulting, while others were reactivated as strike-slip faults. The 81- to 76-Ma Boulder batholith was emplaced along the reactivated central Paleoproterozoic suture in the Great Falls tectonic zone. Early-stage Boulder batholith plutons were emplaced concurrent with east-directed thrust faulting and localized primarily by northwest-trending strike-slip and related faults. The late-stage Butte Quartz Monzonite pluton was localized in a northeast-trending pull-apart structure that formed behind the active thrust front and is axially symmetric across the underlying northeast-striking Paleoproterozoic fault zone, interpreted as a crustal suture. The modeling of potential-field geophysical data indicates that pull-apart?stage magmas fed into the structure through two funnel-shaped zones beneath the batholith. Renewed magmatic activity in the southern feeder from 66 to 64 Ma led to the formation of two small porphyry-style copper-molybdenum deposits and ensuing world-class polymetallic copper- and silver-bearing veins in the Butte mining district. Vein orientations

  10. The State High Biodiesel Project

    ERIC Educational Resources Information Center

    Heasley, Paul L.; Van Der Sluys, William G.

    2009-01-01

    Through a collaborative project in Pennsylvania, high school students developed a method for converting batches of their cafeteria's waste fryer oil into biodiesel using a 190 L (50 gal) reactor. While the biodiesel is used to supplement the school district's heating and transportation energy needs, the byproduct--glycerol--is used to make hand…

  11. Small baseline subsets approach of DInSAR for investigating land surface deformation along the high-speed railway

    NASA Astrophysics Data System (ADS)

    Rao, Xiong; Tang, Yunwei

    2014-11-01

    Land surface deformation evidently exists in a newly-built high-speed railway in the southeast of China. In this study, we utilize the Small BAseline Subsets (SBAS)-Differential Synthetic Aperture Radar Interferometry (DInSAR) technique to detect land surface deformation along the railway. In this work, 40 Cosmo-SkyMed satellite images were selected to analyze the spatial distribution and velocity of the deformation in study area. 88 pairs of image with high coherence were firstly chosen with an appropriate threshold. These images were used to deduce the deformation velocity map and the variation in time series. This result can provide information for orbit correctness and ground control point (GCP) selection in the following steps. Then, more pairs of image were selected to tighten the constraint in time dimension, and to improve the final result by decreasing the phase unwrapping error. 171 combinations of SAR pairs were ultimately selected. Reliable GCPs were re-selected according to the previously derived deformation velocity map. Orbital residuals error was rectified using these GCPs, and nonlinear deformation components were estimated. Therefore, a more accurate surface deformation velocity map was produced. Precise geodetic leveling work was implemented in the meantime. We compared the leveling result with the geocoding SBAS product using the nearest neighbour method. The mean error and standard deviation of the error were respectively 0.82 mm and 4.17 mm. This result demonstrates the effectiveness of DInSAR technique for monitoring land surface deformation, which can serve as a reliable decision for supporting highspeed railway project design, construction, operation and maintenance.

  12. Internal deformation in layered Zechstein-III K-Mg salts. Structures formed by complex deformation and high contrasts in viscosity observed in drill cores.

    NASA Astrophysics Data System (ADS)

    Raith, Alexander; Urai, Janos L.

    2016-04-01

    During the evaporation of a massive salt body, alternations of interrupted and full evaporation sequences can form a complex layering of different lithologies. Viscosity contrasts of up to five orders of magnitude between these different lithologies are possible in this environment. During the late stage of an evaporation cycle potassium and magnesium (K-Mg) salts are precipitated. These K-Mg salts are of economic interest but also a known drilling hazard due to their very low viscosity. How up to 200m thick layers of these evaporites affect salt deformation at different scales is not well known. A better understanding of salt tectonics with extreme mechanical stratification is needed for better exploration and production of potassium-magnesium salts and to predict the internal structure of potential nuclear waste repositories in salt. To gain a better understanding of the internal deformation of these layers we analyzed K-Mg salt rich drill cores out of the Zechstein III-1b subunit from the Veendam Pillow 10 km southeast of Groningen, near the city Veendam in the NE Netherlands. The study area has a complex geological history with multiple tectonic phases of extension and compression forming internal deformation in the pillow but also conserving most of the original layering. Beside halite the most common minerals in the ZIII-1b are carnallite, kieserite, anhydrite and bischofite alternating in thin layers of simple composition. Seismic interpretation revealed that the internal structure of the Veendam Pillow shows areas, in which the K-Mg salt rich ZIII 1b layer is much thicker than elsewhere, as a result of salt deformation. The internal structure of the ZIII-1b on the other hand, remains unknown. The core analysis shows a strong strain concentration in the weaker Bischofite (MgCl2*6H20) and Carnallite (KMgCl3*6H20) rich layers producing tectonic breccias and highly strained layers completely overprinting the original layering. Layers formed by alternating beds

  13. Millimetre wave spectroscopy of high Rydberg states

    NASA Astrophysics Data System (ADS)

    Merkt, F.; Osterwalder, A.

    We have recently developed high-resolution vacuum ultraviolet laser sources and combined these with millimetre waves in double-resonance experiments to achieve a spectral resolution of up to 60 kHz in the spectra of high Rydberg states. The article describes the main features of our experimental procedure and presents studies in which we have used millimetre wave spectroscopy (a) to obtain information on the energy level structure, including the spin-orbit and hyperfine structure, of atomic Rydberg states at high principal quantum numbers n , (b) to record spectrally resolved spectra of the high Rydberg states ( n ≥100) detected in pulsed-field-ionization zero-kinetic-energy photoelectron spectra, (c) to measure stray electric fields and ion concentrations in the gas phase, (d) to test and improve the selectivity of the electric field ionization of high Rydberg states and (e) to observe for the first time the hyperfine structure in high- n , low- l molecular Rydberg states.

  14. High temperature deformation mechanisms of L12-containing Co-based superalloys

    NASA Astrophysics Data System (ADS)

    Titus, Michael Shaw

    Ni-based superalloys have been used as the structural material of choice for high temperature applications in gas turbine engines since the 1940s, but their operating temperature is becoming limited by their melting temperature (Tm =1300degrees C). Despite decades of research, no viable alternatives to Ni-based superalloys have been discovered and developed. However, in 2006, a ternary gamma' phase was discovered in the Co-Al-W system that enabled a new class of Co-based superalloys to be developed. These new Co-based superalloys possess a gamma-gamma' microstructure that is nearly identical to Ni-based superalloys, which enables these superalloys to achieve extraordinary high temperature mechanical properties. Furthermore, Co-based alloys possess the added benefit of exhibiting a melting temperature of at least 100degrees C higher than commercial Ni-based superalloys. Superalloys used as the structural materials in high pressure turbine blades must withstand large thermomechanical stresses imparted from the rotating disk and hot, corrosive gases present. These stresses induce time-dependent plastic deformation, which is commonly known as creep, and new superalloys must possess adequate creep resistance over a broad range of temperature in order to be used as the structural materials for high pressure turbine blades. For these reasons, this research focuses on quantifying high temperature creep properties of new gamma'-containing Co-based superalloys and identifying the high temperature creep deformation mechanisms. The high temperature creep properties of new Co- and CoNi-based alloys were found to be comparable to Ni-based superalloys with respect to minimum creep rates and creep-rupture lives at 900degrees C up to the solvus temperature of the gamma' phase. Co-based alloys exhibited a propensity for extended superlattice stacking fault formation in the gamma' precipitates resulting from dislocation shearing events. When Ni was added to the Co-based compositions

  15. High temperature deformation and fracture mechanisms in a dendritic Ni[sub 3]Al alloy

    SciTech Connect

    Kim, H.K.; Earthman, J.C. . Dept. of Mechanical and Aerospace Engineering)

    1994-03-01

    The mechanisms that control high temperature deformation and rupture were studied in a Ni[sub 3]Al alloy that was thermo-mechanically treated to produce a non-porous dendritic grain structure. Comparisons of data corresponding to the dendritic grain morphology with that for the equiaxed grain structures indicate that the dendritic morphology results in significantly lower creep rates as well as substantially greater times to rupture. Comparison of the data with numerical calculations suggests that this difference in creep strength is due to an inherent resistance to grain boundary sliding by the dendritic grain structure. A constrained cavity growth model was adapted based on microstructural observations to account for cavitation within the dendritic microstructure. The success of the model indicates that rupture time is primarily determined by constrained cavity growth on isolated dendrite boundary segments.

  16. Thermomechanical model for the plastic deformation in high power laser diodes during operation

    NASA Astrophysics Data System (ADS)

    Martín-Martín, A.; Avella, M.; Iñiguez, M. P.; Jiménez, J.; Oudart, M.; Nagle, J.

    2009-10-01

    A thermomechanical model for the mechanism of rapid degradation of AlGaAs based high power laser bars (808 nm) is presented. Thermal stresses induced in the device by local heating around a facet defect by nonradiative recombination and self-absorption of photons are calculated, as well as the conditions for the beginning of plastic deformation, when these thermal stresses overcome the yield strength. The values of the power density and of the local temperature at which the yield limit is surmounted are in agreement with the threshold values for the degradation of Al based lasers given in the literature. The present model can also elucidate the role played by the packaging stress, being able to explain how this stress reduces the optical power density threshold for failure of these lasers.

  17. Deformation increase of high-spin core-excited isomers in the astatine nuclei

    SciTech Connect

    Scheveneels, G.; Hardeman, F.; Neyens, G.; Coussement, R. )

    1991-06-01

    Quadrupole moments of six high-spin isomers in the At isotopes have been measured with the level-mixing-spectroscopy method: {sup 208}At(16{sup {minus}}), {sup 209}At(29/2{sup +}), {sup 210}At(19{sup +},15{sup {minus}}), {sup 211}At(39/2{sup {minus}},29/2{sup +}). The results show that level mixing spectroscopy is a promising technique to determine quadrupole moments of isomers that are difficult to measure by other in-beam hyperfine interaction methods. A large increase of the quadrupole moment is observed if neutrons are excited across or removed from the {ital N}=126 shell closure. This behavior is explained in terms of an enhanced core softness for fewer core neutrons; the aligned valence particles, moving in equatorial orbits, then easily polarize the core towards oblate deformation.

  18. FE Analysis on Shear Deformation for Asymmetrically Hot-Rolled High-Manganese Steel Strip

    NASA Astrophysics Data System (ADS)

    Sui, Feng-Li; Wang, Xin; Li, Chang-Sheng; Zhao, Jun

    2016-11-01

    Shear deformation along the longitudinal cross section of the high-manganese steel strip has been analyzed in hot asymmetrical rolling process using rigid-plastic finite element model. The friction coefficient between the rolls and the strip surfaces, the diameter of the work rolls, the speed ratio for the lower/upper rolls, the reduction rate and the initial temperature of the billet were all taken into account. Influence of these process parameters on the shear stress, the shear strain and the related shear strain energy in the center layer of the hot-rolled strip was analyzed. It is indicated that increasing the speed ratio, the reduction rate and the work roll diameter is an effective way to accumulate more shear strain energy in the strip center. A mathematical model reflecting the relationship between the shear strain energy and the process parameters has been established.

  19. Defects interaction processes in deformed high purity polycrystalline molybdenum at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Lambri, O. A.; Bonifacich, F. G.; Bozzano, P. B.; Zelada, G. I.; Plazaola, F.; García, J. A.

    2014-10-01

    Mechanical spectroscopy (damping and elastic modulus as a function of temperature) and transmission electron microscopy studies have been performed in high purity polycrystalline molybdenum plastically deformed to different values of tensile and torsion strain. Mechanical spectroscopy measurements were performed from room temperature up to 1285 K. A relaxation peak in polycrystalline molybdenum related to the movement of dislocations into lower energy configurations near grain boundaries has been discovered to appear around 1170 K. The activation energy of the peak is 4.2 eV ± 0.5 eV. This relaxation phenomenon involves the interaction between vacancies and mobile dislocations near the grain boundaries. It should be highlighted that this relaxation process is controlled by the arrangement of vacancies and dislocations which occur at temperature below 1070 K.

  20. Steady contemporary deformation of the central Basin and Range Province, western United States

    NASA Astrophysics Data System (ADS)

    Hammond, William C.; Blewitt, Geoffrey; Kreemer, Corné

    2014-06-01

    We use data from western U.S. GPS networks to estimate the rate, pattern, and style of tectonic deformation of the central Basin and Range Province (BRP). Previous geodetic investigations have found the crust of eastern Nevada and western Utah to act as a rigid microplate, with zero deformation rates to within measurement uncertainty. Observed transients in GPS time series have led others to propose a megadetachment model, predicting that the central BRP behaves as a microplate, but with time-varying translation. Here we reassess these hypotheses, benefiting from a significant increase in GPS stations and time span, and innovations in analysis techniques. Our results show that the BRP crust deforms everywhere and all the time. In a group of 24 stations between longitude -113.5° and -116.8°, we find strain rates of 1.9 ± 0.2 × 10-9 yr-1 extension directed N55°W and 2.2 ± 0.2 × 10-9 yr-1 contraction directed N35°E, inconsistent with microplate behavior. The linearity of time series of strain from GPS station triplets is inconsistent with episodic translation of quasi-rigid domains. One exception is station EGAN that exhibits nonlinear motion not found in adjacent stations. The dominant signal in Nevada is distributed shear consistent with Pacific/North America relative plate motion, suggesting that stresses are transmitted through the lithosphere at least 800 km from the plate boundary. The observed active extension is consistent with earthquake focal mechanisms and is in agreement with integrated rates estimated from earthquake geology. Our results do not support the proposed megadetachment in the BRP.

  1. Hot deformation mechanism and microstructure evolution of an ultra-high nitrogen austenitic steel containing Nb and V

    NASA Astrophysics Data System (ADS)

    Zhang, Rong-hua; Zhou, Ze-an; Guo, Ming-wei; Qi, Jian-jun; Sun, Shu-hua; Fu, Wan-tang

    2015-10-01

    The flow curves of an ultra-high nitrogen austenitic steel containing niobium (Nb) and vanadium (V) were obtained by hot compression deformation at temperatures ranging from 1000°C to 1200°C and strain rates ranging from 0.001 s-1 to 10 s-1. The mechanical behavior during hot deformation was discussed on the basis of flow curves and hot processing maps. The microstructures were analyzed via scanning electron microscopy and electron backscatter diffraction. The relationship between deformation conditions and grain size after dynamic recrystallization was obtained. The results show that the flow stress and peak strain both increase with decreasing temperature and increasing strain rate. The hot deformation activation energy is approximately 631 kJ/mol, and a hot deformation equation is proposed. (Nb,V)N precipitates with either round, square, or irregular shapes are observed at the grain boundaries and in the matrix after deformation. According to the discussion, the hot working should be processed in the temperature range of 1050°C to 1150°C and in the strain rate range of 0.01 to 1 s-1.

  2. Strength variation and deformational behavior in anisotropic granitic mylonites under high-temperature and -pressure conditions - An experimental study

    NASA Astrophysics Data System (ADS)

    Liu, Gui; Zhou, Yongsheng; Shi, Yaolin; Miao, Sheqiang; He, Changrong

    2017-03-01

    We performed deformation experiments on foliated granitic mylonites under high-temperature and -pressure conditions. To investigate the effects of pre-existing fabric properties on the rheology of the rocks, these experiments were carried out at different compression directions 30°, 45°, and 60° relative to the foliation, at temperatures of 600-850 °C, under confining pressures of 800-1200 MPa, within a strain rate range of 1 × 10-4/S - 2.5 × 10-6/S. The results of the experiments show that the deformation of three group samples is in the semi-brittle region at temperatures between 600 and 700 °C, and that the deformation of the samples transforms to plastic deformation by power-law creep with the stress exponent n = 3 ± 0.3 at temperatures between 800 and 850 °C. In the semi-brittle region, the mechanical data show that strength reaches its minimum value at an angle of 30° between the compression direction and the original foliation. In the plastic deformation regime, strength reaches its minimum value at an angle of 45° between the foliation and the orientation of the maximum principal stress. The strength with angles between 30° and 60° is lower than that of the compression direction perpendicular to foliation and the compression direction parallel to foliation. Microstructure analysis based on optical and electron microscopy of the deformation microstructures showed plastic deformation of aggregates of biotite and quartz at 800-850 °C. This deformation was extensive and formed new foliation. Quartz c-axis fabrics analysis by EBSD show that at temperatures of 600-700 °C, the c-axis fabric patterns could have been formed by the dominant activity of basal slip, similar with the starting granitic mylonite samples, but the dominant slip systems have been changed and transformed from basal slip to rhomb slip and prism slip at temperature of 800 °C and 850 °C. Microfractures were developed in hornblende and feldspar grains with local

  3. Evolution of the Structural-Phase State of a Ti-Al- V-Mo Alloy During Severe Plastic Deformation and SubSequent Annealing

    NASA Astrophysics Data System (ADS)

    Grabovetskaya, G. P.; Ratochka, I. V.; Mishin, I. P.; Zabudchenko, O. V.; Lykova, O. N.

    2016-05-01

    The effect of the initial phase composition of a Ti-Al-V-Mo alloy (VT16 according to Russian classification) on the evolution of its structural-phase state during the formation of ultrafine-grained structure and subsequent annealing is investigated by methods of optical and transmission electron microscopy and x-ray diffraction analysis. The structure is produced by cyclic pressing with a change of the deformation axis in each cycle combined with a gradual decrease of the pressing temperature from 1073 to 723 K. As this takes place, α″ → α + β and β → α phase transitions are found to develop in the test alloy. The phase state of the ultrafinegrained material thus produced depends for the most part on its elemental composition and severe plastic deformation regime. Annealing below the recrystallization temperature is shown to give rise to a β→α phase transition and alloying element redistribution. The foregoing processes allow for retaining a high level of the strength properties of the alloy.

  4. Decay out of the yrast and excited highly-deformed bands in the even-even nucleus {sup 134}Nd

    SciTech Connect

    Petrache, C.M.; Bazzacco, D.; Lunardi, S.

    1996-12-31

    The resolving power achieved by the new generation of {gamma}-ray detector arrays allows now to observe transitions with intensities of the order of {approximately}10{sup {minus}3} of the population of the final residual nucleus, making therefore feasible the study of the very weakly populated excited bands built on the superdeformed (SD) minimum or of the decay out of the SD bands. As a matter of fact, numerous excited SD bands have been observed in the different regions of superdeformation, which led to a deeper understanding of the single-particle excitation in the second minimum. The first experimental breakthrough in the study of the decay out process has been achieved in the odd-even {sup 133,135}Nd nuclei of the A=130 mass region. There, the observation of the discrete linking transitions has been favored by the relatively higher intensity of the highly-deformed (HD) bands ({approximately}10%), as well as by the small excitation energy with respect to the yrast line in the decay-out region ({approximately}1 MeV). No discrete linking transitions have been so far observed in the A=80, 150 mass regions. The present results suggest that the decay out of the HD bands in {sup 134}Nd is triggered by the crossing with the N=4 [402]5/2{sup +} Nilsson orbital, that has a smaller deformation than the corresponding N=6 intruder configuration. The crossing favours the mixing with the ND rotational bands strongly enhancing the decay-out process and weakening the in-band transition strength. The HD band becomes fragmented and looses part of its character. The intensity of the decay-out transitions increases when the spin of the HD state decreases, indicating enhanced ND amplitude in the wavefunction when going down the band. Lifetime measurements of the HD bands are crucial to further elucidate the decay-out process.

  5. Near-surface neotectonic deformation associated with seismicity in the northeastern United States

    SciTech Connect

    Alexander, S.S.; Gold, D.P.; Gardner, T.W.; Slingerland, R.L.; Thornton, C.P. . Dept. of Geosciences)

    1989-10-01

    For the Lancaster, PA seismic zone a multifaceted investigation revealed several manifestations of near-surface, neotectonic deformation. Remote sensing data together with surface geological and geophysical observations, and recent seismicity reveal that the neotectonic deformation is concentrated in a NS-trending fault zone some 50 km in length and 10--20 km in width. Anomalies associated with this zone include distinctive lineament and surface erosional patterns; geologically recent uplift evidenced by elevations of stream terraces along the Susquehanna River; and localized contemporary travertine deposits in streams down-drainage from the inferred active fault zone. In the Moodus seismic zone the frequency of tectonically-controlled lineaments was observed to increase in the Moodus quadrangle compared to adjacent areas and dominant lineament directions were observed that are perpendicular and parallel to the orientation of the maximum horizontal stress direction (N80-85E) recently determined from in-situ stress measurements in a 1.5 km-deep borehole in the seismic zone and from well-constrained earthquake focal mechanisms. 284 refs., 33 figs.

  6. GNSS seismometer: Seismic phase recognition of real-time high-rate GNSS deformation waves

    NASA Astrophysics Data System (ADS)

    Nie, Zhaosheng; Zhang, Rui; Liu, Gang; Jia, Zhige; Wang, Dijin; Zhou, Yu; Lin, Mu

    2016-12-01

    High-rate global navigation satellite systems (GNSS) can potentially be used as seismometers to capture short-period instantaneous dynamic deformation waves from earthquakes. However, the performance and seismic phase recognition of the GNSS seismometer in the real-time mode, which plays an important role in GNSS seismology, are still uncertain. By comparing the results of accuracy and precision of the real-time solution using a shake table test, we found real-time solutions to be consistent with post-processing solutions and independent of sampling rate. In addition, we analyzed the time series of real-time solutions for shake table tests and recent large earthquakes. The results demonstrated that high-rate GNSS have the ability to retrieve most types of seismic waves, including P-, S-, Love, and Rayleigh waves. The main factor limiting its performance in recording seismic phases is the widely used 1-Hz sampling rate. The noise floor also makes recognition of some weak seismic phases difficult. We concluded that the propagation velocities and path of seismic waves, macro characteristics of the high-rate GNSS array, spatial traces of seismic phases, and incorporation of seismographs are all useful in helping to retrieve seismic phases from the high-rate GNSS time series.

  7. Field-induced expansion deformation in Pb islands on Cu(111): evidence from energy shift of empty quantum-well states.

    PubMed

    Chan, W Y; Huang, H S; Su, W B; Lin, W H; Jeng, H-T; Wu, M K; Chang, C S

    2012-04-06

    We use scanning tunneling microscopy and spectroscopy to measure the energy shift of empty quantum-well (QW) states in Pb islands on the Cu(111) surface. It is found that, with an increase of the electric field, the behavior of the energy shift can be grouped into two different modes for most QW states. In the first mode, the state energy moves toward high energy monotonically. In the second mode, the state energy shifts to a lower energy initially and then turns around to a higher energy. Moreover, we have observed that the QW states of higher energy behave in preference to the first mode, but they gradually change to the second mode as the Pb island becomes thicker. This thickness-dependent behavior reflects the existence of local expansion in the Pb islands, due to the electric field, and that the expansion is larger for a thicker island. QW states can thus be used for studying the localized lattice deformation in the nanometer scale.

  8. Mechanical properties and constitutive relations for tantalum and tantalum alloys under high-rate deformation

    SciTech Connect

    Chen, S.R.; Gray, G.T. III; Bingert, S.R.

    1996-05-01

    Tantalum and its alloys have received increased interest as a model bcc metal and for defense-related applications. The stress-strain behavior of several tantalums, possessing varied compositions and manufacturing histories, and tantalum alloyed with tungsten, was investigated as a function of temperature from {minus}196 C to 1,000 C, and strain rate from 10{sup {minus}3} s{sup {minus}1} to 8,000 s{sup {minus}1}. The yield stress for all the Ta-materials was found to be sensitive to the test temperature, the impurity and solute contents; however, the strain hardening remained very similar for various ``pure`` tantalums but increased with alloying. Powder-metallurgy (P/M) tantalum with various levels of oxygen content produced via different processing paths was also investigated. Similar mechanical properties compared to conventionally processed tantalums were achieved in the P/M Ta. This data suggests that the frequently observed inhomogeneities in the mechanical behavior of tantalum inherited from conventional processes can be overcome. Constitutive relations based upon the Johnson-Cook, the Zerilli-Armstrong, and the Mechanical Threshold Stress models were evaluated for all the Ta-based materials. Parameters were also fit for these models to a tantalum-bar material. Flow stresses of a Ta bar stock subjected to a large-strain deformation of {var_epsilon} = 1.85 via multiple upset forging were obtained. The capabilities and limitations of each model for large-strain applications are examined. The deformation mechanisms controlling high-rate plasticity in tantalum are revisited.

  9. An in situ high voltage electron microscopy technique for the study of deformation and fracture: In multilayered materials

    SciTech Connect

    Wall, M.A.; Barbee, T.W. Jr.; Weihs, T.P.

    1995-04-14

    A novel, in situ, high voltage electron microscopy technique for the direct observation of the micromechanisms of tensile deformation and fracture in nanostructured materials is detailed. This technique is particularly well suited for the dynamic observations of deformation and fracture in multilayered materials. The success of this type of in situ technique is highly dependent upon unique specimen preparation procedures and sample design, the importance thereof will be discussed. The initial observations discussed here are expected to aid in the understanding of the mechanical behavior of this new class of atomically engineered materials.

  10. Deformation behavior of duplex austenite and ε-martensite high-Mn steel.

    PubMed

    Kwon, Ki Hyuk; Suh, Byeong-Chan; Baik, Sung-Il; Kim, Young-Woon; Choi, Jong-Kyo; Kim, Nack J

    2013-02-01

    Deformation and work hardening behavior of Fe-17Mn-0.02C steel containing ε-martensite within the austenite matrix have been investigated by means of in situ microstructural observations and x-ray diffraction analysis. During deformation, the steel shows the deformation-induced transformation of austenite → ε-martensite → α'-martensite as well as the direct transformation of austenite → α'-martensite. Based on the calculation of changes in the fraction of each constituent phase, we found that the phase transformation of austenite → ε-martensite is more effective in work hardening than that of ε-martensite → α'-martensite. Moreover, reverse transformation of ε-martensite → austenite has also been observed during deformation. It originates from the formation of stacking faults within the deformed ε-martensite, resulting in the formation of 6H-long periodic ordered structure.

  11. Constitutive Modeling of Hot Deformation Behavior of High-Strength Armor Steel

    NASA Astrophysics Data System (ADS)

    Bobbili, Ravindranadh; Madhu, Vemuri

    2016-05-01

    The hot isothermal compression tests of high-strength armor steel under a wide range of deformation temperatures (1100-1250 °C) and strain rates of (0.001-1/s) were performed. Based on the experimental data, constitutive models were established using the original Johnson-Cook (JC) model, modified JC model, and strain-compensated Arrhenius model, respectively. The modified JC model considers the coupled effects of strain hardening, strain rate hardening, and thermal softening. Moreover, the prediction accuracy of these developed models was determined by estimating the correlation coefficient ( R) and average absolute relative error (AARE). The results demonstrate that the flow behavior of high-strength armor steel is considerably influenced by the strain rate and temperature. The original JC model is inadequate to provide good description on the flow stress at evaluated temperatures. The modified JC model and strain-compensated Arrhenius model significantly enhance the predictability. It is also observed from the microstructure study that at low strain rates (0.001-0.01/s) and high temperatures (1200-1250 °C), a typical dynamic recrystallization (DRX) occurs.

  12. Demonstration of symmetric dark holes using two deformable mirrors at the high-contrast imaging testbed

    NASA Astrophysics Data System (ADS)

    Riggs, A. J. Eldorado; Groff, Tyler D.; Carlotti, Alexis; Kasdin, N. Jeremy; Cady, Eric J.; Kern, Brian D.; Kuhnert, Andreas

    2013-09-01

    The High Contrast Imaging Laboratory (HCIL) at Princeton has developed several important algorithms and technologies for space-based coronagraphy missions to detect earth-like exoplanets. Before June 2013 the HCIL was the only facility with two deformable mirrors (DMs) in series for focal plane wavefront control, which allows for quasi-static speckle correction on both sides of the image plane. From June through August 2013, the High- Contrast Imaging Testbed (HCIT) at JPL had a second DM installed. In this paper we report on the results of our Technology Development for Exoplanet Missions project to achieve high contrast in two symmetric dark holes using a shaped pupil (SP) coronagraph at the HCIT. Our previous experiment with a similar SP at the HCIT in 2007 yielded single-sided dark holes. That experiment utilized an iterative, batch-process wavefront estimator and Electric Field Conjugation for wavefront control. Our current tests use the faster Kalman filter estimator and the stroke minimization control algorithm. We use the same ripple-style SPs as in the previous HCIT experiment because that mask manufacturing technique proved successful. Our tests of symmetric dark holes in monochromatic light at the HCIT demonstrate Princeton's steady improvements in wavefront control and estimation techniques for a space-based coronagraphy mission.

  13. In-situ tube burst testing and high-temperature deformation behavior of candidate materials for accident tolerant fuel cladding

    SciTech Connect

    Byun, Thak Sang; Yamamoto, Yukinori; Maloy, Stuart A.; Gussev, M. N.; Terrani, K. A.

    2015-08-25

    Here, one of the most essential properties of accident tolerant fuel (ATF) for maintaining structural integrity during a loss-of-coolant accident (LOCA) is high resistance of the cladding to plastic deformation and burst failure, since the deformation and burst behavior governs the cooling efficiency of flow channels and the process of fission product release. To simulate and evaluate the deformation and burst process of thin-walled cladding, an in-situ testing and evaluation method has been developed on the basis of visual imaging and image analysis techniques. The method uses a specialized optics system consisting of a high-resolution video camera, a light filtering unit, and monochromatic light sources. The in-situ testing is performed using a 50 mm long pressurized thin-walled tubular specimen set in a programmable furnace. As the first application, ten (10) candidate cladding materials for ATF, i.e., five FeCrAl alloys and five nanostructured steels, were tested using the newly developed method, and the time-dependent images were analyzed to produce detailed deformation and burst data such as true hoop stress, strain (creep) rate, and failure stress. Relatively soft FeCrAl alloys deformed and burst below 800 °C, while negligible strain rates were measured for higher strength alloys.

  14. In-situ tube burst testing and high-temperature deformation behavior of candidate materials for accident tolerant fuel cladding

    SciTech Connect

    Gussev, Maxim N.; Byun, Thak Sang; Yamamoto, Yukinori; Maloy, Stuart A.; Terrani, Kurt A.

    2015-11-01

    The high resistance of cladding to plastic deformation and burst failure is one of the most essential properties of accident tolerant fuel (ATF) for maintaining structural integrity during a loss-of-coolant accident (LOCA) since the deformation and burst behavior governs the cooling efficiency of flow channels and process of fission product release. To simulate and evaluate such deformation and burst process of thin-walled cladding, an in-situ testing and evaluation method has been developed on the basis of visual imaging and image analysis techniques. The method uses a specialized optics system consisted of a high-resolution video camera, light filtering unit, and monochromatic light sources, and the in-situ testing is performed using a 50 mm long pressurized thin-walled tubular specimen set in a programmable furnace. In this study eleven (11) candidate cladding materials for ATF, i.e., 6 FeCrAl alloys and 5 nanostructured steels, were tested using the newly developed method, and the time-dependent images were analyzed to produce detailed deformation and burst data such as true hoop stress, strain (creep) rate, and failure stress. Relatively soft FeCrAl alloys deformed and burst below 800°C while negligible strain rates were measured for higher strength alloys and/or for relatively thick wall specimens.

  15. In-situ tube burst testing and high-temperature deformation behavior of candidate materials for accident tolerant fuel cladding

    DOE PAGES

    Byun, Thak Sang; Yamamoto, Yukinori; Maloy, Stuart A.; ...

    2015-08-25

    Here, one of the most essential properties of accident tolerant fuel (ATF) for maintaining structural integrity during a loss-of-coolant accident (LOCA) is high resistance of the cladding to plastic deformation and burst failure, since the deformation and burst behavior governs the cooling efficiency of flow channels and the process of fission product release. To simulate and evaluate the deformation and burst process of thin-walled cladding, an in-situ testing and evaluation method has been developed on the basis of visual imaging and image analysis techniques. The method uses a specialized optics system consisting of a high-resolution video camera, a light filteringmore » unit, and monochromatic light sources. The in-situ testing is performed using a 50 mm long pressurized thin-walled tubular specimen set in a programmable furnace. As the first application, ten (10) candidate cladding materials for ATF, i.e., five FeCrAl alloys and five nanostructured steels, were tested using the newly developed method, and the time-dependent images were analyzed to produce detailed deformation and burst data such as true hoop stress, strain (creep) rate, and failure stress. Relatively soft FeCrAl alloys deformed and burst below 800 °C, while negligible strain rates were measured for higher strength alloys.« less

  16. Metastable alloy materials produced by solid state reaction of compacted, mechanically deformed mixtures

    DOEpatents

    Atzmon, M.; Johnson, W.L.; Verhoeven, J.D.

    1987-02-03

    Bulk metastable, amorphous or fine crystalline alloy materials are produced by reacting cold-worked, mechanically deformed filamentary precursors such as metal powder mixtures or intercalated metal foils. Cold-working consolidates the metals, increases the interfacial area, lowers the free energy for reaction, and reduces at least one characteristic dimension of the metals. For example, the grains of powder or the sheets of foil are clad in a container to form a disc. The disc is cold-rolled between the nip of rollers to form a flattened disc. The grains are further elongated by further rolling to form a very thin sheet of a lamellar filamentary structure containing filaments having a thickness of less than 0.01 microns. Thus, diffusion distance and time for reaction are substantially reduced when the flattened foil is thermally treated in oven to form a composite sheet containing metastable material dispersed in unreacted polycrystalline material. 4 figs.

  17. Efficient High-Pressure State Equations

    NASA Technical Reports Server (NTRS)

    Harstad, Kenneth G.; Miller, Richard S.; Bellan, Josette

    1997-01-01

    A method is presented for a relatively accurate, noniterative, computationally efficient calculation of high-pressure fluid-mixture equations of state, especially targeted to gas turbines and rocket engines. Pressures above I bar and temperatures above 100 K are addressed The method is based on curve fitting an effective reference state relative to departure functions formed using the Peng-Robinson cubic state equation Fit parameters for H2, O2, N2, propane, methane, n-heptane, and methanol are given.

  18. Accuracy analysis of continuous deformation monitoring using BeiDou Navigation Satellite System at middle and high latitudes in China

    NASA Astrophysics Data System (ADS)

    Jiang, Weiping; Xi, Ruijie; Chen, Hua; Xiao, Yugang

    2017-02-01

    As BeiDou Navigation Satellite System (BDS) has been operational in the whole Asia-Pacific region, it means a new GNSS system with a different satellite orbit structure will become available for deformation monitoring in the future. Conversely, GNSS deformation monitoring data are always processed with a regular interval to form displacement time series for deformation analysis, where the interval can neither be too long from the time perspective nor too short from the precision of determined displacements angle. In this paper, two experimental platforms were designed, with one being at mid-latitude and another at higher latitude in China. BDS data processing software was also developed for investigating the accuracy of continuous deformation monitoring using current in-orbit BDS satellites. Data over 20 days at both platforms were obtained and were processed every 2, 4 and 6 h to generate 3 displacement time series for comparison. The results show that with the current in-orbit BDS satellites, in the mid-latitude area it is easy to achieve accuracy of 1 mm in horizontal component and 2-3 mm in vertical component; the accuracy could be further improved to approximately 1 mm in both horizontal and vertical directions when combined BDS/GPS measurements are employed. At higher latitude, however, the results are not as good as expected due to poor satellite geometry, even the 6 h solutions could only achieve accuracy of 4-6 and 6-10 mm in horizontal and vertical components, respectively, which implies that it may not be applicable to very high-precision deformation monitoring at high latitude using the current BDS. With the integration of BDS and GPS observations, however, in 4-h session, the accuracy can achieve 2 mm in horizontal component and 4 mm in vertical component, which would be an optimal choice for high-accuracy structural deformation monitoring at high latitude.

  19. In situ observation of crystallographic preferred orientation of deforming olivine at high pressure and high temperature

    NASA Astrophysics Data System (ADS)

    Ohuchi, T.; Nishihara, Y.; Seto, Y.; Kawazoe, T.; Nishi, M.; Maruyama, G.; Hashimoto, M.; Higo, Y.; Funakoshi, K. I.; Suzuki, A.; Kikegawa, T.; Irifune, T.

    2015-12-01

    Olivine is the main constituent mineral in Earth's upper mantle, and its crystallographic preferred orientation (CPO) controls the seismic anisotropy in the upper mantle. Because the relationship between fabric strength and seismic anisotropy shows an exponential form (Ismail and Mainprice, 1998), seismic anisotropy in the upper mantle is expected to have an upperlimit value. Hansen et al., (2014) demonstrated that a steady-state fabric of olivine is not reached until a very large shear strain (γ> 10) and fabric strength of olivine increases up to the J-index of 10-30 at 0.3 GPa. However, the strain dependency on the fabric strength of olivine needs to be evaluated at asthenospheric upper mantle pressures (2-13 GPa) because the relative activity of each slip system in olivine changes depending on pressure (e.g., Raterron et al., 2007). We experimentally evaluated the strain dependency of fabric strength of olivine in simple-shear geometry under upper mantle conditions (pressures of 1.3-3.8 GPa and temperatures of 1223-1573 K). The CPO of olivine was calculated from in-situ two-dimensional X-ray diffraction patterns. In the calculation, we simulated the optimized CPO which reproduces the two-dimensional X-ray diffraction pattern adopted from the experiments. The steady-state fabric strength of the A-type fabric was achieved within total shear strain of γ = 2. At strains higher than γ = 1, an increase in concentration of the [010] axes mainly contributes to an increase in fabric strength. At strains higher than γ = 2, the magnitude of VSH/VSV (i.e., ratio of horizontally and vertically polarized shear wave velocities) scarcely increased in most of the runs. The VSH/VSV of peridotite having the steady-state A-type olivine fabric coincides with that of recent global one-dimensional models under the assumption of horizontal flow, suggesting that the seismic anisotropy observed in the shallow upper mantle is mostly explained by the development of A-type olivine

  20. TRP 9904 - Constitutive Behavior of High Strength Multiphase Sheel Steel Under High Strain Rate Deformation

    SciTech Connect

    David Matlock; John Speer

    2005-03-31

    The focus of the research project was to systematically assess the strain rate dependence of strengthening mechanisms in new advanced high strength sheet steels. Data were obtained on specially designed and produced Duel Phase and TRIP steels and compared to the properties of automotive steels currently in use.

  1. (p,q) deformations and (p,q)-vector coherent states of the Jaynes-Cummings model in the rotating wave approximation

    SciTech Connect

    Ben Geloun, Joseph; Govaerts, Jan; Hounkonnou, M. Norbert

    2007-03-15

    Classes of (p,q) deformations of the Jaynes-Cummings model in the rotating wave approximation are considered. Diagonalization of the Hamiltonian is performed exactly, leading to useful spectral decompositions of a series of relevant operators. The latter include ladder operators acting between adjacent energy eigenstates within two separate infinite discrete towers, except for a singleton state. These ladder operators allow for the construction of (p,q)-deformed vector coherent states. Using (p,q) arithmetics, explicit and exact solutions to the associated moment problem are displayed, providing new classes of coherent states for such models. Finally, in the limit of decoupled spin sectors, our analysis translates into (p,q) deformations of the supersymmetric harmonic oscillator, such that the two supersymmetric sectors get intertwined through the action of the ladder operators as well as in the associated coherent states.

  2. Subsurface deformation in hypervelocity cratering experiments into high-porosity tuffs

    NASA Astrophysics Data System (ADS)

    Winkler, Rebecca; Poelchau, Michael H.; Moser, Stefan; Kenkmann, Thomas

    2016-10-01

    Hypervelocity impact experiments on porous tuff targets were carried out to determine the effect of porosity on deformation mechanisms in the crater's subsurface. Blocks of Weibern Tuff with about 43% porosity were impacted by 2.5 mm and 12.0 mm diameter steel spheres with velocities between 4.8 km s-1 and 5.6 km s-1. The postimpact subsurface damage was quantified with computer tomography as well as with meso- and microscale analyses of the bisected crater subsurface. The intensity and style of deformation in mineral clasts and the tuff matrix were mapped and their decay with subsurface depth was determined. Subsurface deformation styles include pore space compaction, clast rotation, as well as microfracture formation. Evaluation of the deformation indicates near-surface energy coupling at a calculated depth of burial of 2 projectile diameters (dp), which is in conflict with the crater shape, which displays a deep, central penetration tube. Subsurface damage extends to 2 dp beneath the crater floor in the experiments with 2.5 mm projectiles and increases to 3 dp for 12 mm projectiles. Based on overprinting relationships and the geometrical orientation of deformation features, a sequence of subsurface deformation events was derived (1) matrix compaction, (2) intragranular crack formation in clasts, (3) deformation band formation in the compacted matrix, (4) tensile fracturing.

  3. High-power visible-laser effect on a 37-segment Iris AO deformable mirror

    NASA Astrophysics Data System (ADS)

    Norton, Andrew; Gavel, Donald; Dillon, Daren

    2010-02-01

    We have tested an aluminum-coated Iris AO Micro-Electrical Mechanical System (MEMS) segmented Deformable Mirror (DM) for its behavior in the presence of high energy 532 nm laser light. The DM was subject to several tests in which the laser power and the duration of its incidence was varied. The DM experienced an irradiance of 94.5 W cm-2 at the maximum laser power of 2 W. A slight permanent reduction in the amount of bow in each segment was observed. This is most likely due to annealing. The mirror remained fully functional during and after the tests. Measurements of the mirror's temporal stability and position repeatability were performed before the laser test. We found a 1.28 nm rms variation in the bow of segments that is highly correlated over the 16 minute test. The mirror's ability to return to its initial position was within the 1.34 nm rms instrument noise. These results are encouraging for applications such as the laser uplink correction of the Visible Light Laser Guidestar Experiment (Villages) and future multi-Laser Guidestar systems (LGS).

  4. A high throughput approach for analysis of cell nuclear deformability at single cell level

    PubMed Central

    Ermis, Menekse; Akkaynak, Derya; Chen, Pu; Demirci, Utkan; Hasirci, Vasif

    2016-01-01

    Various physiological and pathological processes, such as cell differentiation, migration, attachment, and metastasis are highly dependent on nuclear elasticity. Nuclear morphology directly reflects the elasticity of the nucleus. We propose that quantification of changes in nuclear morphology on surfaces with defined topography will enable us to assess nuclear elasticity and deformability. Here, we used soft lithography techniques to produce 3 dimensional (3-D) cell culture substrates decorated with micron sized pillar structures of variable aspect ratios and dimensions to induce changes in cellular and nuclear morphology. We developed a high content image analysis algorithm to quantify changes in nuclear morphology at the single-cell level in response to physical cues from the 3-D culture substrate. We present that nuclear stiffness can be used as a physical parameter to evaluate cancer cells based on their lineage and in comparison to non-cancerous cells originating from the same tissue type. This methodology can be exploited for systematic study of mechanical characteristics of large cell populations complementing conventional tools such as atomic force microscopy and nanoindentation. PMID:27841297

  5. A high throughput approach for analysis of cell nuclear deformability at single cell level

    NASA Astrophysics Data System (ADS)

    Ermis, Menekse; Akkaynak, Derya; Chen, Pu; Demirci, Utkan; Hasirci, Vasif

    2016-11-01

    Various physiological and pathological processes, such as cell differentiation, migration, attachment, and metastasis are highly dependent on nuclear elasticity. Nuclear morphology directly reflects the elasticity of the nucleus. We propose that quantification of changes in nuclear morphology on surfaces with defined topography will enable us to assess nuclear elasticity and deformability. Here, we used soft lithography techniques to produce 3 dimensional (3-D) cell culture substrates decorated with micron sized pillar structures of variable aspect ratios and dimensions to induce changes in cellular and nuclear morphology. We developed a high content image analysis algorithm to quantify changes in nuclear morphology at the single-cell level in response to physical cues from the 3-D culture substrate. We present that nuclear stiffness can be used as a physical parameter to evaluate cancer cells based on their lineage and in comparison to non-cancerous cells originating from the same tissue type. This methodology can be exploited for systematic study of mechanical characteristics of large cell populations complementing conventional tools such as atomic force microscopy and nanoindentation.

  6. Adaptive Optics System with Deformable Composite Mirror and High Speed, Ultra-Compact Electronics

    NASA Astrophysics Data System (ADS)

    Chen, Peter C.; Knowles, G. J.; Shea, B. G.

    2006-06-01

    We report development of a novel adaptive optics system for optical astronomy. Key components are very thin Deformable Mirrors (DM) made of fiber reinforced polymer resins, subminiature PMN-PT actuators, and low power, high bandwidth electronics drive system with compact packaging and minimal wiring. By using specific formulations of fibers, resins, and laminate construction, we are able to fabricate mirror face sheets that are thin (< 2mm), have smooth surfaces and excellent optical shape. The mirrors are not astigmatic and do not develop surface irregularities when cooled. The actuators are small footprint multilayer PMN-PT ceramic devices with large stroke (2- 20 microns), high linearity, low hysteresis, low power, and flat frequency response to >2 KHz. By utilizing QorTek’s proprietary synthetic impendence power supply technology, all the power, control, and signal extraction for many hundreds to 1000s of actuators and sensors can be implemented on a single matrix controller printed circuit board co-mounted with the DM. The matrix controller, in turn requires only a single serial bus interface, thereby obviating the need for massive wiring harnesses. The technology can be scaled up to multi-meter aperture DMs with >100K actuators.

  7. Deformation mechanisms for high-temperature creep of high yttria content stabilized zirconia single crystals

    SciTech Connect

    Gomez-Garcia, D.; Martinez-Fernandez, J.; Dominguez-Rodriguez, A.; Eveno, P.; Castaing, J.

    1996-03-01

    Creep of 21 mol.% yttria-stabilized zirconia single crystals has been studied between 1,400 and 1,800 C. The creep parameters have been determined indicating a change of the controlling mechanism around 1,500 C. At higher temperatures recovery creep is found to be the rate controlling mechanism, with a stress exponent {approx_equal} 3 and an activation energy {approx_equal} 6 eV. Transition to glide controlled creep occurs below 1,500 C, associated with larger stress exponents ({approx_equal} 5) and activation energies ({approx_equal} 8.5 eV). TEM observations of the dislocation microstructure confirm this transition. The influence of the high yttria content, which is at the origin of the high creep resistance of these crystals, is discussed for each range of temperatures.

  8. Towards a high resolution inventory of anthropogenic deformation in North America using InSAR

    NASA Astrophysics Data System (ADS)

    Pritchard, M. E.; Lohman, R. B.; Taylor, H.; Semple, A.; Valentino, B.

    2015-12-01

    Anthropogenic surface deformation is important to measure for several reasons -- 1) it could be a hazard to infrastructure; 2) it could contaminate precise measurements of other types of deformation (e.g., magmatic or tectonic); and 3) the deformation can provide otherwise inaccessible information about the subsurface as we measure the Earth's response to known pumping, surface change, or mining activity. While there are studies at individual sites in North America that demonstrate these three types of studies, we lack a continental synoptic view of anthropogenic deformation and its significance. To fill this gap, we use satellite Interferometric Synthetic Aperture Radar (InSAR) data to image ground deformation across the continent with a spatial resolution of 1 km/pixel or better using results from the literature as well as new analysis of more than 5000 interferograms from the ERS, Envisat, and ALOS satellites, which collectively span 1992-2011. Our compilation is not complete in terms of spatially or temporal coverage nor is it uniform in quality over the region -- certainly we have missed some areas of deformation. Most of the data analyzed is in the western US, but ALOS observations east of the Rocky Mountains are of good quality even in vegetated and snowy areas and we document mining subsidence greater than several cm per year in NY, PA, and WV. We catalog more than 200 anthropogenic deformation signals, including about 45 that are not previously reported. The majority of these deformation sources can be attributed to groundwater extraction (66%), 8% to geothermal activity, 13% to hydrocarbon extraction, 11% to mining activity, and 2% to other sources such as lake loading. In a few areas, the source of deformation is not yet determined. As expected, most deformation is time dependent and so continuous monitoring is needed. In some areas, comparisonbetween pumping records and surface deformation reveals some suprises. For example, at the East Mesa Geothermal

  9. Effects of different levels of compression during sub-maximal and high-intensity exercise on erythrocyte deformability.

    PubMed

    Wahl, Patrick; Bloch, Wilhelm; Mester, Joachim; Born, Dennis-Peter; Sperlich, Billy

    2012-06-01

    The aim of the study was to test the hypothesis whether different levels of sock compression (0, 10, 20, and 40 mmHg) affect erythrocyte deformability and metabolic parameters during sub-maximal and maximal running. Nine well-trained, male endurance athletes (age 22.2 ± 1.3 years, peak oxygen uptake 57.7 ± 4.5 mL min(-1) kg(-1)) carried out four periods of sub-maximal running at 70% of peak oxygen uptake for 30 min followed by a ramp test until exhaustion with and without compression socks that applied different levels of pressure. Erythrocyte deformability, blood lactate, heart rate and arterial partial pressure of oxygen (pO(2)) were monitored before and during all of these tests. Erythrocyte deformability, heart rate, pO(2) and lactate concentration were unaffected by compression, whereas exercise itself significantly increased erythrocyte deformability. However, the increasing effects of exercise were attenuated when high compression was applied. This first evaluation of the potential effects of increasing levels of compression on erythrocyte deformability and metabolic parameters during (sub-) maximal exercise, revealed no effects whatsoever.

  10. State-by-State Analysis of High School Feedback Reports

    ERIC Educational Resources Information Center

    Data Quality Campaign, 2013

    2013-01-01

    The best information to help stakeholders evaluate and strengthen their efforts to improve students' college and career readiness is actual information about students' success beyond high school, such as enrollment, remediation, degree and certification completion, and employment outcomes. States have a critical role to plan in providing…

  11. Study of a wide-aperture combined deformable mirror for high-power pulsed phosphate glass lasers

    SciTech Connect

    Samarkin, V V; Aleksandrov, A G; Romanov, P N; Rukosuev, A L; Kudryashov, A V; Jitsuno, T

    2015-12-31

    A deformable mirror with the size of 410 × 468 mm controlled by bimorph piezoceramic plates and multilayer piezo stacks is developed. The response functions of individual actuators and the measurements of the flatness of the deformable mirror surface are presented. The study of mirrors with an interferometer and a wavefront sensor has shown that it is possible to improve the surface flatness down to a residual roughness of 0.033 μm (RMS). The possibility of correction of beam aberrations in an ultra-high-power laser using the created bimorph mirror is demonstrated. (letters)

  12. Initial state geometry and fluctuations in deformed and asymmetric nuclear collisions in the IP-Glasma framework

    NASA Astrophysics Data System (ADS)

    Schenke, Björn; Tribedy, Prithwish; Venugopalan, Raju

    2014-11-01

    The IP-Glasma model of initial conditions based on the ab initio color glass condensate framework successfully explains most of the bulk features of the global data for various systems like p+p, p+A and A+A over a wide range of energies. We employ this framework to study deformed U+U collisions, asymmetric Cu+Au collisions and the effect of deformation in Au+Au collisions at RHIC. A combined study of these heavy ion systems with varying initial geometries can provide a unique opportunity to determine the origin of different sources of fluctuations that affect global observables like multiplicity and flow. We study the sensitivity of multiplicity, eccentricity and their event-by-event distributions to the details of initial state geometry. Results are compared to a two-component MC-Glauber model implementation that includes Negative-Binomial multiplicity fluctuations. We argue that the measurements of global observables for these systems at RHIC can constrain the mechanism of multi-particle production.

  13. Mechanical and structural aspects of high-strain-rate deformation of NiTi alloy

    NASA Astrophysics Data System (ADS)

    Bragov, A. M.; Danilov, A. N.; Konstantinov, A. Yu.; Lomunov, A. K.; Motorin, A. S.; Razov, A. I.

    2015-04-01

    The mechanical behavior of the binary polycrystalline NiTi alloy with a quasi-equilibrium structure has been considered in the course of the high-strain-rate extension in a temperature range of 20-300°C. The quasi-equilibrium structure, which is necessary to ensure the long-term stability of special properties of the alloy, was achieved using aging, after which both the forward and reverse martensitic transformations exhibited a multistage character and the phase composition at room temperature was characterized by the presence of R and B19' martensites. To separate the contributions that come from the equilibrium structure and from the high rate of tension to the mechanical behavior of the alloy, a comparative analysis of the diagrams of high-strain-rate and quasi-static tension has been performed. It has been shown that the action of several mechanisms of reversible deformation is determined by the specific features of the equilibrium structure, and the level of stresses at which these mechanisms are developed is controlled by the rate of tension. The results of the X-ray diffraction study of the phase composition of the alloy samples after high-strain-rate tension, which make it possible to conclude that the mechanical behavior of martensite and austenite upon the dynamic tension of the alloy is determined by the development of stress-induced R → B19', B2 → R, and B2 → B19' transformations and by the processes of the detwinning and reorientation of crystals of B19' martensite, are given.

  14. SU(3) gauge symmetry for collective rotational states in deformed nuclei

    NASA Astrophysics Data System (ADS)

    Rosensteel, George; Sparks, Nick

    2016-09-01

    How do deformed nuclei rotate? The qualitative answer is that a velocity-dependent interaction causes a strong coupling between the angular momentum and the vortex momentum (or Kelvin circulation). To achieve a quantitative explanation, we propose a significant extension of the Bohr-Mottelson legacy model in which collective wave functions are vector-valued in an irreducible representation of SU(3). This SU(3) is not the usual Elliott choice, but rather describes internal vorticity in the rotating frame. The circulation values C of an SU(3) irreducible representation, say the (8,0) for 20Ne, are C = 0, 2, 4, 6, 8, which is the same as the angular momentum spectrum in the Elliott model; the reason is a reciprocity theorem in the symplectic model. The differential geometry of Yang-Mills theory provides a natural mathematical framework to solve the angular-vortex coupling riddle. The requisite strong coupling is a ``magnetic-like'' interaction arising from the covariant derivative and the bundle connection. The model builds on prior work about the Yang-Mills SO(3) gauge group model.

  15. Metastable alloy materials produced by solid state reaction of compacted, mechanically deformed mixtures

    DOEpatents

    Atzmon, Michael; Johnson, William L.; Verhoeven, John D.

    1987-01-01

    Bulk metastable, amorphous or fine crystalline alloy materials are produced by reacting cold-worked, mechanically deformed filamentary precursors such as metal powder mixtures or intercalated metal foils. Cold-working consolidates the metals, increases the interfacial area, lowers the free energy for reaction, and reduces at least one characteristic dimension of the metals. For example, the grains (13) of powder or the sheets of foil are clad in a container (14) to form a disc (10). The disc (10) is cold-rolled between the nip (16) of rollers (18,20) to form a flattened disc (22). The grains (13) are further elongated by further rolling to form a very thin sheet (26) of a lamellar filamentary structure (FIG. 4) containing filaments having a thickness of less than 0.01 microns. Thus, diffusion distance and time for reaction are substantially reduced when the flattened foil (28) is thermally treated in oven (32) to form a composite sheet (33) containing metastable material (34) dispersed in unreacted polycrystalline material (36).

  16. Toward high-speed 3D nonlinear soft tissue deformation simulations using Abaqus software.

    PubMed

    Idkaidek, Ashraf; Jasiuk, Iwona

    2015-12-01

    We aim to achieve a fast and accurate three-dimensional (3D) simulation of a porcine liver deformation under a surgical tool pressure using the commercial finite element software Abaqus. The liver geometry is obtained using magnetic resonance imaging, and a nonlinear constitutive law is employed to capture large deformations of the tissue. Effects of implicit versus explicit analysis schemes, element type, and mesh density on computation time are studied. We find that Abaqus explicit and implicit solvers are capable of simulating nonlinear soft tissue deformations accurately using first-order tetrahedral elements in a relatively short time by optimizing the element size. This study provides new insights and guidance on accurate and relatively fast nonlinear soft tissue simulations. Such simulations can provide force feedback during robotic surgery and allow visualization of tissue deformations for surgery planning and training of surgical residents.

  17. Geometry and deformation history of the New Madrid seismic zone fault system, Central U.S. from high-resolution marine seismic reflection data, and implications for intraplate deformation

    NASA Astrophysics Data System (ADS)

    Guo, L.; Magnani, M.; McIntosh, K. D.; Waldron, B. A.; Saustrup, S.; Fave, X. J.

    2010-12-01

    The New Madrid Seismic Zone (NMSZ) is the most seismically active area in the continental United States east of the Rocky Mountains, and by far the most studied intraplate seismic zone in the world. The occurrence of large magnitude historical and prehistorical earthquakes, as well as the high level of instrumental seismicity suggest that the North American plate is actively deforming in this region. This observation appears to clash with geodetic evidence that shows minimal motion across the faults illuminated by the present seismicity, suggesting that either the present GPS vectors recorded at the surface are not typical of the long term deformation rate of the NMSZ faults, or that the NMSZ fault system is presently unloaded and not deforming. To better constrain the long-term deformation history of the NMSZ fault system, in the summer of 2010 we acquired ~300 km of high-resolution seismic marine reflection data along the Mississippi River from Cape Girardeau, MO to Caruthersville, MO. The profile crosses a large portion of the Mississippi Embayment, including three of the four main NMSZ active faults, and images the gently south-dipping unconsolidated sediments of the Mississippi Embayment from the Quaternary alluvium of the Mississippi River down to the top of Paleozoic sequences, at a depth of ~650 m. Among the most remarkable structures imaged by the profile is the Reelfoot fault, interpreted as the NW-SE striking restraining bend connecting two NE-SW trending dextral strike-slip faults. The Reelfoot thrust intersects the profile at three locations along the river meander known as the Kentucky Bend. The multiple crossings allow mapping of the along-strike variations of the fault plane’s dip and structure. In particular the data show that a reverse offset of 42 m at the top of the Cretaceous is accommodated by a single fault at the crossing north of town of Tiptonville, TN, west of the location where the Reelfoot thrust ruptured during the 7 February 1812 M7

  18. Some observations on cyclic deformation structures in the high-strength commercial aluminum alloy AA 7150

    SciTech Connect

    Hanlon, D.N.; Rainforth, W.M.

    1998-11-01

    Load-controlled fatigue testing of the aluminum alloy AA 7150 has been conducted using four-point bending with an R ratio of + 0.1 over a range of maximum stress levels from 60 to 120% of the 0.2% proof stress. The alloy, in the form of 12.5-mm rolled plate, was investigated in underaged (UA), peak-aged (PA), and overaged (OA) conditions, corresponding to a change in average precipitate sizes from 5 nm in the UA condition to 21 nm in the OA condition. Three orientations of the plate were investigated. Orientation and aging condition influenced the degree of surface topographical development but not fatigue life. Detailed transmission electron microscopy (TEM) of the fatigued surface indicated that deformation in all aging conditions occurred by planar slip. Slip was generally restricted to a single slip system within each grain, and subgrain boundaries offered little resistance to dislocation movement facilitating long slip line lengths (measured up to 310 {micro}m) between adjacent high-angle grain boundaries. Planar slip observed in the OA condition is attributed to shearing of large strengthening precipitates, which is promoted by long slip line lengths. No evidence of surface specific changes in slip character was observed.

  19. Three-dimensionally deformable, highly stretchable, permeable, durable and washable fabric circuit boards

    PubMed Central

    Li, Qiao; Tao, Xiao Ming

    2014-01-01

    This paper reports fabric circuit boards (FCBs), a new type of circuit boards, that are three-dimensionally deformable, highly stretchable, durable and washable ideally for wearable electronic applications. Fabricated by using computerized knitting technologies at ambient dry conditions, the resultant knitted FCBs exhibit outstanding electrical stability with less than 1% relative resistance change up to 300% strain in unidirectional tensile test or 150% membrane strain in three-dimensional ball punch test, extraordinary fatigue life of more than 1 000 000 loading cycles at 20% maximum strain, and satisfactory washing capability up to 30 times. To the best of our knowledge, the performance of new FCBs has far exceeded those of previously reported metal-coated elastomeric films or other organic materials in terms of changes in electrical resistance, stretchability, fatigue life and washing capability as well as permeability. Theoretical analysis and numerical simulation illustrate that the structural conversion of knitted fabrics is attributed to the effective mitigation of strain in the conductive metal fibres, hence the outstanding mechanical and electrical properties. Those distinctive features make the FCBs particularly suitable for next-to-skin electronic devices. This paper has further demonstrated the application potential of the knitted FCBs in smart protective apparel for in situ measurement during ballistic impact. PMID:25383032

  20. Microstructural evolution and mechanical properties of high strength magneisum alloys fabricated by deformation processing

    NASA Astrophysics Data System (ADS)

    Mansoor, Bilal

    The goal of this research was to develop high strength Mg by thermo-mechanical processing. Several novel techniques were developed to impart large plastic strains on Mg alloys and Mg based composites. The main emphasis of this work was on investigating the effect of different processing schemes on grain-refinement and texture modification of processed material. The room-temperature and elevated-temperature mechanical behavior of processed-Mg was studied in detail. Biaxial corrugated pressing, also known as alternate biaxial reverse corrugation processing was applied to twin-roll cast AZ31 Mg and warm-extruded ZK60 Mg. Friction stir processing to partial depths was applied to thixomolded AM60 Mg and warm-extruded ZK60 Mg. A new process called "bending reverse-bending", was developed and applied to hot rolled AZ31-H24 Mg. A Mg/Al laminated composite was developed by hot pressing and rolling. In processed condition, Mg alloys exhibit enhancement in room-temperature strength and ductility, as well as elevated temperature formability. It was concluded that improvement in mechanical properties of processed-Mg is strongly influenced by grain size and precipitates; while ductility largely depends on resulting deformation textures.

  1. Influence of high temperature pre-deformation on the dissolution rate of delta ferrites in martensitic heat-resistant steels

    NASA Astrophysics Data System (ADS)

    Li, Junru; Liu, Jianjun; Jiang, Bo; Zhang, Chaolei; Liu, Yazheng

    2017-03-01

    The dissolution process of delta ferrites and the influence of high temperature pre-deformation on the dissolution rate of delta ferrites in martensitic heat-resistant steel 10Cr12Ni3Mo2VN were studied by isothermal heating and thermal simulation experiments. The precipitation temperature of delta ferrites in experimental steel is about 1195 °C. M23C6-type carbides incline to precipitate and coarsen at the boundaries of delta ferrites below 930 °C, and can be rapidly dissolved by heating at 1180 °C. The percentage of delta ferrites gradually decreases with heating time. And a Kolmogorov-Johnson-Mehl-Avrami equation was established to describe the dissolution process of delta ferrites at 1180 °C. High temperature pre-deformation can markedly increase the dissolution rate of delta ferrites. Pre-deformation can largely increase the interface area between delta ferrite and matrix and thus increase the unit-time diffusing quantities of alloying elements between delta ferrites and matrix. In addition, high temperature pre-deformation leads to dynamic recrystallization and increases the number of internal grain boundaries in the delta ferrites. This can also greatly increase the diffusing rate of alloying elements. In these cases, the dissolution of delta ferrites can be promoted.

  2. Influence of high temperature pre-deformation on the dissolution rate of delta ferrites in martensitic heat-resistant steels

    NASA Astrophysics Data System (ADS)

    Li, Junru; Liu, Jianjun; Jiang, Bo; Zhang, Chaolei; Liu, Yazheng

    2017-02-01

    The dissolution process of delta ferrites and the influence of high temperature pre-deformation on the dissolution rate of delta ferrites in martensitic heat-resistant steel 10Cr12Ni3Mo2VN were studied by isothermal heating and thermal simulation experiments. The precipitation temperature of delta ferrites in experimental steel is about 1195 °C. M23C6-type carbides incline to precipitate and coarsen at the boundaries of delta ferrites below 930 °C, and can be rapidly dissolved by heating at 1180 °C. The percentage of delta ferrites gradually decreases with heating time. And a Kolmogorov-Johnson-Mehl-Avrami equation was established to describe the dissolution process of delta ferrites at 1180 °C. High temperature pre-deformation can markedly increase the dissolution rate of delta ferrites. Pre-deformation can largely increase the interface area between delta ferrite and matrix and thus increase the unit-time diffusing quantities of alloying elements between delta ferrites and matrix. In addition, high temperature pre-deformation leads to dynamic recrystallization and increases the number of internal grain boundaries in the delta ferrites. This can also greatly increase the diffusing rate of alloying elements. In these cases, the dissolution of delta ferrites can be promoted.

  3. On the deformation mechanisms and electrical behavior of highly stretchable metallic interconnects on elastomer substrates

    NASA Astrophysics Data System (ADS)

    Arafat, Yeasir; Dutta, Indranath; Panat, Rahul

    2016-09-01

    Flexible metallic interconnects are highly important in the emerging field of deformable/wearable electronics. In our previous work [Arafat et al., Appl. Phys. Lett. 107, 081906 (2015)], interconnect films of Indium metal, periodically bonded to an elastomer substrate using a thin discontinuous/cracked adhesion interlayer of Cr, were shown to sustain a linear strain of 80%-100% without failure during repeated cycling. In this paper, we investigate the mechanisms that allow such films to be stretched to a large strain without rupture along with strategies to prevent a deterioration in their electrical performance under high linear strain. Scanning Electron Microscopy and Digital Image Correlation are used to map the strain field of the Cr adhesion interlayer and the In interconnect film when the elastomer substrate is stretched. It is shown that the Cr interlayer morphology, consisting of islands separated by bi-axial cracks, accommodates the strain primarily by widening of the cracks between the islands along the tensile direction. This behavior is shown to cause the strain in the In interconnect film to be discontinuous and concentrated in bands perpendicular to the loading direction. This localization of strain at numerous periodically spaced locations preempts strain-localization at one location and makes the In film highly stretchable by delaying rupture. Finally, the elastic-plastic mismatch-driven wrinkling of the In interconnect upon release from first loading cycle is utilized to delay the onset of plasticity and allow the interconnect to be stretched repeatedly up to 25% linear strain in subsequent cycles without a deterioration of its electrical performance.

  4. Relativistic Bound States in the Presence of Spherically Ring-Shaped q-DEFORMED Woods-Saxon Potential with Arbitrary l-STATES

    NASA Astrophysics Data System (ADS)

    Ikhdair, Sameer M.; Hamzavi, Majid; Rajabi, A. A.

    2013-03-01

    Approximate bound-state solutions of the Dirac equation with q-deformed Woods-Saxon (WS) plus a new generalized ring-shaped (RS) potential are obtained for any arbitrary l-state. The energy eigenvalue equation and corresponding two-component wave functions are calculated by solving the radial and angular wave equations within a shortcut of the Nikiforov-Uvarov (NU) method. The solutions of the radial and polar angular parts of the wave function are expressed in terms of the Jacobi polynomials. A new approximation being expressed in terms of the potential parameters is carried out to deal with the strong singular centrifugal potential term l(l+1)r-2. Under some limitations, we can obtain solution for the RS Hulthén potential and the standard usual spherical WS potential (q = 1).

  5. The effect of high density electric pulses on sintered aluminum 201AB silicon carbide MMC PM compacts during plastic deformation

    NASA Astrophysics Data System (ADS)

    Dariavach, Nader Guseinovich

    The effect of high-density electrical pulses on mechanical and structural properties of sintered aluminum SiC metal-matrix composites, fabricated by standard powder-metallurgy compaction and sintering, was investigated. Three types of phenomena where investigated during transverse rupture testing of the samples: a consolidation effect (increasing of the transverse rupture strength (TRS)), an electroplastic effect (decreasing of the flow stresses), and an increasing of the stress intensity factor by electric pulse application. It was observed, that an increase in the TRS strength of sintered powder metallurgy (PM) aluminum and aluminum metal matrix composite (MMC) compacts is a result of the electric pulse consolidation effect due to non-uniform temperature distribution around the grain boundaries. Three analytical models of the thermal effect of electric pulses on aluminum samples where considered: total temperature change of the sample due to a one electric pulse, one-dimensional steady state model and transient 2D thermal analysis of the temperature distribution around the grain boundary. The 2D transient analysis shows that the temperature rise in the grain boundary of a sintered PM aluminum sample due to an electric pulse can exceed the melting point. At the same time the temperature of the bulk material has an insignificant (<28°C) change. It was found that the electroplastic effect, due to electric pulse application, can account for up to a 40% load drop in aluminum MMC PM compacts. Reduction of flow stresses during plastic deformation could reduce the risk of structural damage, micro-cracks, SiC particle fracture and delamination of the aluminum MMC. These results may find practical application for manufacturing processes such as forging, extrusion, rolling, which involve plastic deformation. It was experimentally proven that a non-uniform temperature distribution around the crack could re-melt the crack tip and increase the strength of the damaged material

  6. Kinetic Monte Carlo study of activated states and correlated shear-transformation-zone activity during the deformation of an amorphous metal

    NASA Astrophysics Data System (ADS)

    Homer, Eric R.; Rodney, David; Schuh, Christopher A.

    2010-02-01

    Shear transformation zone (STZ) dynamics simulations, which are based on the kinetic Monte Carlo algorithm, are used to model the mechanical response of amorphous metals and provide insight into the collective aspects of the microscopic events underlying deformation. The present analysis details the activated states of STZs in such a model, as well as the statistics of their activation and how these are affected by imposed conditions of stress and temperature. The analysis sheds light on the spatial and temporal correlations between the individual STZ activations that lead to different macroscopic modes of deformation. Three basic STZ correlation behaviors are observed: uncorrelated activity, nearest-neighbor correlation, and self-reactivating STZs. These three behaviors correspond well with the macroscopic deformation modes of homogeneous flow, inhomogeneous deformation, and elastic behavior, respectively. The effect of pre-existing stresses in the simulation cell is also studied and found to have a homogenizing effect on STZ correlations, suppressing the tendency for localization.

  7. Direct experimental evidence for a multiparticle-hole ground state configuration of deformed 33Mg

    NASA Astrophysics Data System (ADS)

    Datta, Ushasi; Rahaman, A.; Aumann, T.; Beceiro-Novo, S.; Boretzky, K.; Caesar, C.; Carlson, B. V.; Catford, W. N.; Chakraborty, S.; Chartier, M.; Cortina-Gil, D.; de Angelis, G.; Diaz Fernandez, P.; Emling, H.; Ershova, O.; Fraile, L. M.; Geissel, H.; Gonzalez-Diaz, D.; Jonson, B.; Johansson, H.; Kalantar-Nayestanaki, N.; Kröll, T.; Krücken, R.; Kurcewicz, J.; Langer, C.; Le Bleis, T.; Leifels, Y.; Marganiec, J.; Münzenberg, G.; Najafi, M. A.; Nilsson, T.; Nociforo, C.; Panin, V.; Paschalis, S.; Plag, R.; Reifarth, R.; Ricciardi, V.; Rossi, D.; Scheit, H.; Scheidenberger, C.; Simon, H.; Taylor, J. T.; Togano, Y.; Typel, S.; Volkov, V.; Wagner, A.; Wamers, F.; Weick, H.; Weigand, M.; Winfield, J. S.; Yakorev, D.; Zoric, M.

    2016-09-01

    The first direct experimental evidence of a multiparticle-hole ground state configuration of the neutron-rich 33Mg isotope has been obtained via intermediate energy (400 A MeV) Coulomb dissociation measurement. The major part ˜(70 ±13 )% of the cross section is observed to populate the excited states of 32Mg after the Coulomb breakup of 33Mg. The shapes of the differential Coulomb dissociation cross sections in coincidence with different core excited states favor that the valence neutron occupies both the s1 /2 and p3 /2 orbitals. These experimental findings suggest a significant reduction and merging of s d -p f shell gaps at N ˜20 and 28. The ground state configuration of 33Mg is predominantly a combination of 32Mg(3.0 ,3.5 MeV ;2-,1-) ⨂νs1/2 , 32Mg(2.5 MeV ;2+) ⨂νp3/2 , and 32Mg(0 ;0+) ⨂νp3/2 . The experimentally obtained quantitative spectroscopic information for the valence neutron occupation of the s and p orbitals, coupled with different core states, is in agreement with Monte Carlo shell model (MCSM) calculation using 3 MeV as the shell gap at N =20 .

  8. Influence of high deformation rate, brain region, transverse compression, and specimen size on rat brain shear stress morphology and magnitude.

    PubMed

    Haslach, Henry W; Gipple, Jenna M; Leahy, Lauren N

    2017-01-26

    An external mechanical insult to the brain, such as a blast, may create internal stress and deformation waves, which have shear and longitudinal components that can induce combined shear and compression of the brain tissue. To isolate the consequences of such interactions for the shear stress and to investigate the role of the extracellular fluid in the mechanical response, translational shear stretch at 10/s, 60/s, and 100/s translational shear rates under either 0% or 33% fixed transverse compression is applied without preconditioning to rat brain specimens. The specimens from the cerebrum, the cerebellum grey matter, and the brainstem white matter are nearly the full length of their respective regions. The translational shear stress response to translational shear deformation is characterized by the effect that each of four factors, high deformation rate, brain region, transverse compression, and specimen size, have on the shear stress magnitude averaged over ten specimens for each combination of factors. Increasing the deformation rate increases the magnitude of the shear stress at a given translational shear stretch, and as tested by ANOVAs so does applying transverse fixed compression of 33% of the thickness. The stress magnitude differs by the region that is the specimen source: cerebrum, cerebellum or brainstem. The magnitude of the shear stress response at a given deformation rate and stretch depends on the specimen length, called a specimen size effect. Surprisingly, under no compression a shorter length specimen requires more shear stress, but under 33% compression a shorter length specimen requires less shear stress, to meet a required shear deformation rate. The shear specimen size effect calls into question the applicability of the classical shear stress definition to hydrated soft biological tissue.

  9. Experimental Validation of Two-dimensional Finite Element Method for Simulating Constitutive Response of Polycrystals During High Temperature Plastic Deformation

    NASA Astrophysics Data System (ADS)

    Agarwal, Sumit; Briant, Clyde L.; Krajewski, Paul E.; Bower, Allan F.; Taleff, Eric M.

    2007-04-01

    A finite element method was recently designed to model the mechanisms that cause superplastic deformation (A.F. Bower and E. Wininger, A Two-Dimensional Finite Element Method for Simulating the Constitutive Response and Microstructure of Polycrystals during High-Temperature Plastic Deformation, J. Mech. Phys. Solids, 2004, 52, p 1289-1317). The computations idealize the solid as a collection of two-dimensional grains, separated by sharp grain boundaries. The grains may deform plastically by thermally activated dislocation motion, which is modeled using a conventional crystal plasticity law. The solid may also deform by sliding on the grain boundaries, or by stress-driven diffusion of atoms along grain boundaries. The governing equations are solved using a finite element method, which includes a front-tracking procedure to monitor the evolution of the grain boundaries and surfaces in the solid. The goal of this article is to validate these computations by systematically comparing numerical predictions to experimental measurements of the elevated-temperature response of aluminum alloy AA5083 (M.-A. Kulas, W.P. Green, E.M. Taleff, P.E. Krajewski, and T.R. McNelley, Deformation Mechanisms in Superplastic AA5083 materials. Metall. Mater. Trans. A, 2005, 36(5), p 1249-1261). The experimental work revealed that a transition occurs from grain-boundary sliding to dislocation (solute-drag) creep at approximately 0.001/s for temperatures between 425 and 500 °C. In addition, increasing the grain size from 7 to 10 μm decreased the transition to significantly lower strain rates. Predictions from the finite element method accurately predict the effect of grain size on the transition in deformation mechanisms.

  10. Martensitic transformations and the evolution of the defect microstructure of metastable austenitic steel during severe plastic deformation by high-pressure torsion

    NASA Astrophysics Data System (ADS)

    Litovchenko, I. Yu.; Tyumentsev, A. N.; Akkuzin, S. A.; Naiden, E. P.; Korznikov, A. V.

    2016-08-01

    It has been shown that, in metastable austenitic Fe-18Cr-10Ni-Ti steel, under conditions of torsion under pressure, local reversible (forward plus reverse) (γ → α' → γ) martensitic transformations can occur, which are one of the mechanisms of the formation of nanostructured states. An increase in the rotation rate, which leads to an increase in the deformation temperature, stimulates the reverse (α' → γ) transformation. The evolution of the structural and phase states is represented as the following sequence: (1) mechanical twinning; (2) nucleation of martensitic plates in the microtwinned structure of the austenite with the formation of two-phase (γ + α') structures, packet α' martensite, and structural states with a high curvature of the crystal lattice; (3) reverse (α' → γ)-transformations; and (4) the fragmentation of nanosized crystals via the formation of a nanotwinned structure in the austenite and of a nanoscale banded structure of the ɛ martensite in the α' martensite.

  11. The effect of high temperature deformation on the hot ductility of niobium-microalloyed steel

    NASA Astrophysics Data System (ADS)

    Zarandi, Faramarz Mh

    Low hot ductility at the straightening stage of the steel continuous casting process, where the surface temperature ranges from 600 to 1200°C, is associated with transverse cracking on the billet surface. This is attributed to various microalloying elements, which are essential for the mechanical characteristics of the final products. Thermomechanical processing is a new approach to alleviate this problem. In this work, two grades of Nb-containing steel, one modified with B, were examined. In order to simulate the key parameters of continuous casting, specimens were melted in situ and subjected to thermal conditions similar to that occurring in a continuous casting mill. They were also deformed at different stages of the thermal schedule. Finally, the hot ductility was evaluated at the end of the thermal schedule, corresponding to the straightening stage in continuous casting at which the hot ductility problem occurs in the continuous casting process. The results showed that the presence of B is noticeably beneficial to the hot ductility. Failure mode analysis was performed and the mechanism of fracture was elaborated. As well, the potential mechanisms under which B can improve the hot ductility were proposed. Deformation during solidification (i.e. in the liquid + solid two phase region) led to a significant loss of hot ductility in both steels. By contrast, deformation in the delta-ferrite region, after solidification, was either detrimental or beneficial depending on the deformation start temperature. The hot ductility was considerably improved in the steel without B when deformation was applied during the delta → gamma transformation. The effect of such deformation on the other steel grade was not significant. Examination of the microstructure revealed that such improvement is related to a grain refinement in austenite. Therefore, the effect of deformation parameters was studied in detail and the optimum condition leading to the greatest improvement in the

  12. Efficient High Pressure MixtureState Equations

    NASA Technical Reports Server (NTRS)

    Harstad, K. G.; Miller, R. S.; Bellan, J.

    1996-01-01

    A method is presented for an accurate noniterative, computationally efficient calculation of high pressure fluid mixture equations of state, especially targeted to gas turbines and rocket engines. Pressures above 1 bar and temperatures above 100 K are addressed. The method is based on curve fitting an effective reference state relative to departure funcitons formed using the Peng-Robinson cubic state equation. Fit parameters for H(sub 2), O(sub 2), N(sub 2), propane, n-heptane and methanol are given.

  13. Higher-Orders of Squeezing, Sub-Poissonian Statistics and Anti-Bunching of Deformed Photon-Added Coherent States

    NASA Astrophysics Data System (ADS)

    Aeineh, N.; Tavassoly, M. K.

    2015-08-01

    In this paper, we investigate the higher-order nonclassical properties of a particular class of generalized coherent states namely the deformed photon-added nonlinear coherent states (DPACS) A†m |α, f, m>. To achieve this purpose we pay attention to higher-orders of squeezing (both Hillery- and Hong-Mandel-types), sub-Poissonian statistics and anti-bunching of the mentioned states with a well-known nonlinearity function. It is shown that for enough large values of field intensity (|α|2) for a fixed N (the order of squeezing) by increasing m (the order of excitation) the degree of squeezing evaluated by Hillery and Hong-Mandel approaches increases, while for a chosen fixed value of m, by increasing N for Hillery (Hong-Mandel) type of squeezing the strength of squeezing decreases (increases). Similarly, the degree of higher-order sub-Poissonian statistics (with fixed K) becomes lower when m increases, while (with fixed m) it gets greater values when the order of sub-Poissonian K increases. At last, higher-order anti-bunching of the DPACS is evaluated, by which we established that its (always) negative values increase with increasing m, α and l (the order of anti-bunching) individually, i.e. the degree of anti-bunching increases.

  14. Neutron Diffraction Study of Strain/Stress States and Subgrain Defects in a Creep-Deformed, Single-Crystal Superalloy

    NASA Astrophysics Data System (ADS)

    Wu, Erdong; Sun, Guangai; Chen, BO; Zhang, Jian; Ji, Vincent; Klosek, Vincent; Mathon, Marie-Helene

    2014-01-01

    A single crystal superalloy with initial sample axis 10 deg deviated from [001] was creep deformed at 1273 K (1000 °C) 235 MPa and its triaxial strain/stress state and subgrain defects were studied by neutron diffraction. Normal internal stresses with their directions close to the loading axis and their scales smaller than those perpendicular to the axis were observed and attributed to a lattice rotation toward [001] pole. The internal stress at a level approaching to the loading stress and mostly in the state of interphase stress was induced during the first stage of creep prior to rafting and associated to lattice rotation, microstrain relaxation and line-up of misoriented γ'-precipitates. The internal stress was diminished and released at final stage of creep associated with a reduction in unit-cell volume and a transition of strain/stress state between the two phases. The observation was explained by development of dislocations and raft structure during creep.

  15. High-resolution microdiffraction study of notch-tip deformation in Mo single crystals using x-ray synchrotron radiation

    SciTech Connect

    Ice, G.; Habenschuss, A.; Bilello, J.C.; Rebonato, R.

    1989-12-31

    A new technique is presented for the determination of strain fields in single crystals, based on the simultaneous recording of the energy and position of a diffracted beam, with a resolution of 25 micrometers under current experimental conditions. The technique can be profitably used for perfect to highly deformed crystals, in materials as highly absorbing as Molybdenum, and allows a spatial resolution of one part in 10{sup 4}. Indications are given as to possible refinements and improvements of the method.

  16. High-resolution microdiffraction study of notch-tip deformation in Mo single crystals using x-ray synchrotron radiation

    SciTech Connect

    Ice, G.; Habenschuss, A. ); Bilello, J.C. ); Rebonato, R. . Physical Chemistry Lab.)

    1989-01-01

    A new technique is presented for the determination of strain fields in single crystals, based on the simultaneous recording of the energy and position of a diffracted beam, with a resolution of 25 micrometers under current experimental conditions. The technique can be profitably used for perfect to highly deformed crystals, in materials as highly absorbing as Molybdenum, and allows a spatial resolution of one part in 10{sup 4}. Indications are given as to possible refinements and improvements of the method.

  17. A High-Performance Deformable Mirror with Integrated Driver ASIC for Space Based Active Optics

    NASA Astrophysics Data System (ADS)

    Shelton, Chris

    Direct imaging of exoplanets is key to fully understanding these systems through spectroscopy and astrometry. The primary impediment to direct imaging of exoplanets is the extremely high brightness ratio between the planet and its parent star. Direct imaging requires a technique for contrast suppression, which include coronagraphs, and nulling interferometers. Deformable mirrors (DMs) are essential to both of these techniques. With space missions in mind, Microscale is developing a novel DM with direct integration of DM and its electronic control functions in a single small envelope. The Application Specific Integrated Circuit (ASIC) is key to the shrinking of the electronic control functions to a size compatible with direct integration with the DM. Through a NASA SBIR project, Microscale, with JPL oversight, has successfully demonstrated a unique deformable mirror (DM) driver ASIC prototype based on an ultra-low power switch architecture. Microscale calls this the Switch-Mode ASIC, or SM-ASIC, and has characterized it for a key set of performance parameters, and has tested its operation with a variety of actuator loads, such as piezo stack and unimorph, and over a wide temperature range. These tests show the SM-ASIC's capability of supporting active optics in correcting aberrations of a telescope in space. Microscale has also developed DMs to go with the SM-ASIC driver. The latest DM version produced uses small piezo stack elements in an 8x8 array, bonded to a novel silicon facesheet structure fabricated monolithically into a polished mirror on one side and mechanical linkage posts that connect to the piezoelectric stack actuators on the other. In this Supporting Technology proposal we propose to further develop the ASIC-DM and have assembled a very capable team to do so. It will be led by JPL, which has considerable expertise with DMs used in Adaptive Optics systems, with high-contrast imaging systems for exoplanet missions, and with designing DM driver

  18. Effects of Ce Addition on High Temperature Deformation Behavior of Cu-Cr-Zr Alloys

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Volinsky, Alex A.; Tran, Hai T.; Chai, Zhe; Liu, Ping; Tian, Baohong

    2015-10-01

    Hot deformation behavior of the Cu-Cr-Zr and Cu-Cr-Zr-Ce alloys was investigated by compressive tests using the Glee-ble-1500D thermomechanical simulator at 650-850 °C and 0.001-10 s-1 strain rate. The flow stress decreased with the deformation temperature at a given stain rate. However, the flow stress increased with the strain rate at the same deformation temperature. The constitutive equations for two kinds of alloys were obtained by correlating the flow stress, the strain rate and temperature using stepwise regression analysis. The addition of Ce can refine the grain and effectively accelerate dynamic recrystallization. The processing maps were established, based on the dynamic material model. Instability zones in the flow behavior can be easily recognized. Hot deformation optimal processing parameters were obtained in the range of this experiment. The hot deformation characteristics and microstructure were also analyzed by the processing maps. The addition of Ce can optimize hot workability of the Cu-Cr-Zr alloy.

  19. Effect of the deformation temperature on the structural refinement of BCC metals with a high stacking fault energy during high pressure torsion

    NASA Astrophysics Data System (ADS)

    Voronova, L. M.; Chashchukhina, T. I.; Gapontseva, T. M.; Krasnoperova, Yu. G.; Degtyarev, M. V.; Pilyugin, V. P.

    2016-10-01

    The structural evolution in bcc metals (molybdenum, niobium) with a high stacking fault energy (300 and 200 mJ/m-2, respectively) is studied during high pressure torsion in Bridgman anvils at temperatures of 290 and 80 K. It is established that cryogenic deformation of these metals does not result in twinning; however, banded structures are formed at the initial stage of deformation. Misoriented kink bands, which inhibit the formation of a homogeneous submicrocrystalline structure similarly to twins, form in molybdenum. The banded structures in niobium are characterized by low-angle misorientations; they do not suppress the formation of a submicrocrystalline structure and the refinement of microcrystallites to nanosizes.

  20. Primary transitions between the yrast superdeformed band and low-lying normal deformed states in {sup 194}Pb

    SciTech Connect

    Hauschild, K.; Bernstein, L.A.; Becker, J.A.

    1996-12-31

    The observation of one-step `primary` gamma-ray transitions directly linking the superdeformed (SD) states to the normal deformed (ND) low-lying states of known excitation energies (E{sub x}), spins and parities (J{sup {pi}}) is crucial to determining the E{sub x} and J{sup {pi}} of the SD states. With this knowledge one can begin to address some of the outstanding problems associated with SD nuclei, such as the identical band issue, and one can also place more stringent restrictions on theoretical calculations which predict SD states and their properties. Brinkman, et al., used the early implementation of the GAMMASPHERE spectrometer array (32 detectors) and proposed a single, candidate {gamma} ray linking the {sup 194}Pb yrast SD band to the low-lying ND states in {sup 194}Pb. Using 55 detectors in the GAMMASPHERE array Khoo, et al., observed multiple links between the yrast SD band in {sup 194}Hg and the low-lying level scheme and conclusively determined E{sub x} and J of the yrast SD states. Here the authors report on an experiment in which Gammasphere with 88 detectors was used and the E{sub x} and J{sup {pi}} values of the yrast SD states in {sup 194}Pb were uniquely determined. Twelve one-step linking transitions between the yrast SD band and low-lying states in {sup 194}Pb have been identified, including the transition proposed by Brinkman. These transitions have been placed in the level scheme of {sup 194}Pb using coincidence relationships and agreements between the energies of the primary transitions and the energy differences in level spacings. Furthermore, measurements of angular asymmetries have yielded the multipolarities of the primaries which have allowed J{sup {pi}} assignments of the {sup 194}Pb SD states to be unambiguously determined for the first time without a priori assumptions about the character of SD bands. A study performed in parallel to this work using the EUROGAM-II array reports similar, but somewhat less extensive, results.

  1. The Variation of the Dislocation Density in Aluminum Deformed to Large Steady-State Creep Strains

    DTIC Science & Technology

    1986-03-01

    axis of the specimen) using a South Bay Technology Model 650 Low Speed Diamond Wheel Saw and a high concentration Buehler (.006") wafering blade...primary creep where the material experiences hardening. However, another explanation might be a high initial moble dislocation density associated with

  2. Study of stable isotopes for highly deformed aquifers in the Hsinchu-Miaoli area, Taiwan

    NASA Astrophysics Data System (ADS)

    Lu, Hsueh-Yu; Peng, Tsung-Ren; Liu, Tsung-Kwei; Wang, Chung-Ho; Huang, Chih-Chao

    2006-08-01

    This study was based on the analysis of isotopic compositions of hydrogen and oxygen in samples from precipitation, groundwater and stream water. In addition, parts of groundwater samples were dated by carbon-14 and tritium. These data are integrated to provide other views of the hydrologic cycle in the Hsinchu-Miaoli groundwater district. The groundwater district is principally composed of Pleistocene and Holocene aquifers. The Pleistocene aquifers are highly deformed by folding and faults into small sub-districts with areas of only tens of square kilometers. These aquifers are exclusively recharged by local precipitation. The Holocene aquifers cover narrow creek valleys, only tens of meters in thickness. The local meteoric water line (LMWL), constructed from rainfall samples in the Hsinchu Science Park, is described by the equation δD=8.02δ18O+10.16, which agrees with the global meteoric water line. In addition, the precipitation isotopic compositions can be categorized into two distinct end members: typhoon type and monsoon type. The groundwater isotopic compositions are perfectly located on an LMWL and can be considered a mixture of precipitations. Based on the mass balance of isotopic compositions of oxygen and hydrogen, infiltration is more active in the rainy season with depleted isotopic compositions. The amount of infiltration during May-September is roughly estimated to comprise at least 55% of the whole year’s recharge. The isotopic compositions of stream water are expressed by a regression equation: δD=7.61δ18O+9.62, which is similar to the LMWL. Although precipitation isotopic compositions are depleted during summer time, the isotopic compositions contrarily show an enriched trend in the upstream area. This is explained by the opposite altitude effect on isotopic compositions for typhoon-related precipitations.

  3. The effect of heat developed during high strain rate deformation on the constitutive modeling of amorphous polymers

    NASA Astrophysics Data System (ADS)

    Safari, Keivan H.; Zamani, Jamal; Guedes, Rui M.; Ferreira, Fernando J.

    2016-02-01

    An adiabatic constitutive model is proposed for large strain deformation of polycarbonate (PC) at high strain rates. When the strain rate is sufficiently high such that the heat generated does not have time to transfer to the surroundings, temperature of material rises. The high strain rate deformation behavior of polymers is significantly affected by temperature-dependent constants and thermal softening. Based on the isothermal model which first was introduced by Mulliken and Boyce et al. (Int. J. Solids Struct. 43:1331-1356, 2006), an adiabatic model is proposed to predict the yield and post-yield behavior of glassy polymers at high strain rates. When calculating the heat generated and the temperature changes during the step by step simulation of the deformation, temperature-dependent elastic constants are incorporated to the constitutive equations. Moreover, better prediction of softening phenomena is achieved by the new definition for softening parameters of the proposed model. The constitutive model has been implemented numerically into a commercial finite element code through a user material subroutine (VUMAT). The experimental results, obtained using a split Hopkinson pressure bar, are supported by dynamic mechanical thermal analysis (DMTA) and Decompose/Shift/Reconstruct (DSR) method. Comparison of adiabatic model predictions with experimental data demonstrates the ability of the model to capture the characteristic features of stress-strain curve of the material at very high strain rates.

  4. High-resolution adaptive optics scanning laser ophthalmoscope with multiple deformable mirrors

    DOEpatents

    Chen, Diana C.; Olivier, Scot S.; Jones; Steven M.

    2010-02-23

    An adaptive optics scanning laser ophthalmoscopes is introduced to produce non-invasive views of the human retina. The use of dual deformable mirrors improved the dynamic range for correction of the wavefront aberrations compared with the use of the MEMS mirror alone, and improved the quality of the wavefront correction compared with the use of the bimorph mirror alone. The large-stroke bimorph deformable mirror improved the capability for axial sectioning with the confocal imaging system by providing an easier way to move the focus axially through different layers of the retina.

  5. A comparison of Lagrangian/Eulerian approaches for tracking the kinematics of high deformation solid motion.

    SciTech Connect

    Ames, Thomas L.; Farnsworth, Grant V.; Ketcheson, David Isaac; Robinson, Allen Conrad

    2009-09-01

    The modeling of solids is most naturally placed within a Lagrangian framework because it requires constitutive models which depend on knowledge of the original material orientations and subsequent deformations. Detailed kinematic information is needed to ensure material frame indifference which is captured through the deformation gradient F. Such information can be tracked easily in a Lagrangian code. Unfortunately, not all problems can be easily modeled using Lagrangian concepts due to severe distortions in the underlying motion. Either a Lagrangian/Eulerian or a pure Eulerian modeling framework must be introduced. We discuss and contrast several Lagrangian/Eulerian approaches for keeping track of the details of material kinematics.

  6. High Temperature Deformation Mechanism in Hierarchical and Single Precipitate Strengthened Ferritic Alloys by In Situ Neutron Diffraction Studies

    PubMed Central

    Song, Gian; Sun, Zhiqian; Li, Lin; Clausen, Bjørn; Zhang, Shu Yan; Gao, Yanfei; Liaw, Peter K.

    2017-01-01

    The ferritic Fe-Cr-Ni-Al-Ti alloys strengthened by hierarchical-Ni2TiAl/NiAl or single-Ni2TiAl precipitates have been developed and received great attentions due to their superior creep resistance, as compared to conventional ferritic steels. Although the significant improvement of the creep resistance is achieved in the hierarchical-precipitate-strengthened ferritic alloy, the in-depth understanding of its high-temperature deformation mechanisms is essential to further optimize the microstructure and mechanical properties, and advance the development of the creep resistant materials. In the present study, in-situ neutron diffraction has been used to investigate the evolution of elastic strain of constitutive phases and their interactions, such as load-transfer/load-relaxation behavior between the precipitate and matrix, during tensile deformation and stress relaxation at 973 K, which provide the key features in understanding the governing deformation mechanisms. Crystal-plasticity finite-element simulations were employed to qualitatively compare the experimental evolution of the elastic strain during tensile deformation at 973 K. It was found that the coherent elastic strain field in the matrix, created by the lattice misfit between the matrix and precipitate phases for the hierarchical-precipitate-strengthened ferritic alloy, is effective in reducing the diffusional relaxation along the interface between the precipitate and matrix phases, which leads to the strong load-transfer capability from the matrix to precipitate. PMID:28387230

  7. High spin states of [sup 84]Sr

    SciTech Connect

    Garcia Bermudez, G.; Baktash, C.; Abenante, V.; Griffin, H.C.; Halbert, M.L.; Hensley, D.C.; Johnson, N.R.; Lee, I.Y.; McGowan, F.K.; Riley, M.A.; Sarantites, D.G.; Semkow, T.M.; Stracener, D.W.; Virtanen, A. Joint Institute for Heavy-Ion Research, Oak Ridge, Tennessee 37831 Departamento de Fisica, Comision Nacional de Energia Atomica, 1429 Buenos Aires Department of Chemistry, Washington University, Saint Louis, Missouri 63130 Department of chemistry, University of Michigan, Ann Arbor, Michigan 48104 )

    1994-06-01

    High spin states of [sup 84]Sr nucleus excited through the [sup 52]Cr([sup 36]S,2[ital p]2[ital n]) reaction at 130 MeV energy were studied utilizing the Oak Ridge Compton-Suppression Spectrometer System. The level scheme has been extended up to probably [ital I][sup [pi

  8. States' Progress toward High School Restructuring

    ERIC Educational Resources Information Center

    National High School Center, 2007

    2007-01-01

    As many Title I high schools approach their fifth year of failing to meet adequate yearly progress (AYP), states and districts are struggling to navigate the new waters of school restructuring as required by the No Child Left Behind Act (NCLB) of 2001. This brief outlines the provisions of the law related to restructuring and includes strategies…

  9. HIGH-INTENSITY, HIGH CHARGE-STATE HEAVY ION SOURCES

    SciTech Connect

    ALESSI,J.G.

    2004-08-16

    There are many accelerator applications for high intensity heavy ion sources, with recent needs including dc beams for RIA, and pulsed beams for injection into synchrotrons such as RHIC and LHC. The present status of sources producing high currents of high charge state heavy ions is reviewed. These sources include ECR, EBIS, and Laser ion sources. Benefits and limitations for these type sources are described. Possible future improvements in these sources are also mentioned.

  10. Reduce Nb3Sn Strand Deformation when Fabricating High Jc Rutherford Cables

    SciTech Connect

    Peng, Xuan

    2012-12-17

    During Phase I, our efforts were to reduce subelements deformation when fabricating Nb3Sn Rutherford cables. Our first focus is on 217-sublement tube type strand. We successfully made a few billets in OD tube with different Cu spacing between subelements, and supplied the strands to Fermi Lab for cabling. Through the rolling test characterization, these types of strands did not have enough bonding between subelements to withstand the deformation. We saw copper cracking between subelements in the deformed strands. We scaled up the billet from OD to 1.5 OD, and made two billets. This greatly improves the bonding. There is no copper cracking in the deformed strands when we scaled up the diameter of the billets. Fermi Lab successfully made cables using one of this improved strands. In their cables, no Cu cracking and no filament bridging occurred. We also successfully made a couple of billets with hex OD and round ID subelements for 61-subelement restack. Due to the lack of bonding, we could not judge its cabling property properly. But we know through this experiment, we could keep the Nb round, once we select the proper Cu spacing.

  11. Influence of Grain Boundaries and their Composition on the Deformation Strength of High-purity, Synthetic Forsterite

    NASA Astrophysics Data System (ADS)

    Dillman, Amanda Marie

    Grain boundaries are an important feature of the mantle. With recent studies suggesting the majority of the upper mantle deforms by grain boundary sliding (Hirth and Kohlstedt, 2003; Hansen et al., 2013), understanding the role grain boundaries play is key. As grain boundary sliding always requires an accommodation mechanism, directly determining the contribution of grain boundary sliding to total strain on a sample is important for modeling deformation in the mantle. Altering grain boundary composition can change the structure and viscosity of the boundary. Understanding the effects of grain boundary composition is necessary for comparing data sets of different olivine as well as for accurately extrapolating experimental data to represent the mantle. In Chapter 2, uniaxial deformation experiments on high-purity synthetic forsterite at high temperature and ambient pressure are used to characterize the contribution of grain boundary sliding to strain in diffusion creep. Experiments were conducted in a one-atmosphere deformation rig, which allowed the polished surfaces of the samples to be analyzed with atomic force microscopy. The high temperature necessary for deformation enabled a great deal of thermal grooving, which can dramatically alter the topography of an initially polished surface. A methodology was developed to correct for the effect of thermal grooving and determine the amount of grain boundary sliding as a function of grain size and stress. A comparison is also made between two popular methods for determining grain size: the line intercept method and the equivalent area circle method. The line intercept method consistently produces larger grain sizes than the equivalent area circle method. In Chapter 3, triaxial compression experiments on forsterite are used to determine the effect of grain boundary chemistry on deformation strength. High-purity synthetic forsterite was doped with either Ca or Pr and then deformed at high temperature and a confining

  12. a Method for the Extraction of Long-Term Deformation Characteristics of Long-Span High-Speed Railway Bridges Using High-Resolution SAR Images

    NASA Astrophysics Data System (ADS)

    Jia, H. G.; Liu, L. Y.

    2016-06-01

    Natural causes and high-speed train load will result in the structural deformation of long-span bridges, which greatly influence the safety operation of high-speed railway. Hence it is necessary to conduct the deformation monitoring and regular status assessment for long-span bridges. However for some traditional surveying technique, e.g. control-point-based surveying techniques, a lot of human and material resources are needed to perform the long-term monitoring for the whole bridge. In this study we detected the long-term bridge deformation time-series by persistent scatterer interferometric synthetic aperture radar (PSInSAR) technique using the high-resolution SAR images and external digital elevation model. A test area in Nanjing city in China is chosen and TerraSAR-X images and Tandem-X for this area have been used. There is the Dashengguan bridge in high speed railway in this area as study object to evaluate this method. Experiment results indicate that the proposed method can effectively extract the long-term deformation of long-span high-speed railway bridge with higher accuracy.

  13. Dislocation creep accommodated Grain Boundary Sliding: A high strain rate/low temperature deformation mechanism in calcite ultramylonites

    NASA Astrophysics Data System (ADS)

    Rogowitz, Anna; Grasemann, Bernhard

    2014-05-01

    Grain boundary sliding (GBS) is an important grain size sensitive deformation mechanism that is often associated with extreme strain localization and superplasticity. Another mechanism has to operate simultaneously to GBS in order to prevent overlaps and voids between sliding grains. One of the most common accommodating mechanisms is diffusional creep but, recently, dislocation creep has been reported to operate simultaneous to GBS. Due to the formation of a flanking structure in nearly pure calcite marble on Syros (Cyclades, Greece) at lower greenschist facies conditions, an extremely fine grained ultramylonite developed. The microstructure of the layer is characterized by (1) calcite grains with an average grain size of 3.6 µm (developed by low temperature/high strain rate grain boundary migration recrystallization, BLG), (2) grain boundary triple junctions with nearly 120° angles and (3) small cavities preferentially located at triple junctions and at grain boundaries in extension. These features suggest that the dominant deformation mechanism was GBS. In order to get more information on the accommodation mechanism detailed microstructural and textural analyses have been performed on a FEI Quanta 3D FEG instrument equipped with an EDAX Digiview IV EBSD camera. The misorientation distribution curves for correlated and uncorrelated grains follow almost perfect the calculated theoretical curve for a random distribution, which is typical for polycrystalline material deformed by GBS. However, the crystallographic preferred orientation indicates that dislocation creep might have operated simultaneously. We also report Zener-Stroh cracks resulting from dislocation pile up, indicating that dislocation movement was active. We, therefore, conclude that the dominant deformation mechanism was dislocation creep accommodated grain boundary sliding. This is consistent with the observed grain size range that plots at the field boundary between grain size insensitive and grain

  14. Development of deep-seated gravitational slope deformation on a shale dip-slope: observations from high-quality drillcores

    NASA Astrophysics Data System (ADS)

    Chigira, Masahiro; Hariyama, Takehiro; Yamasaki, Shintaro

    2013-04-01

    The internal structures within a gravitationally deformed slope were observed using high-quality drillcores obtained from a dip slope of a series of shale-dominated sediments. This slope has dimple-like depressions and an overall gentle slope angle, but has no well-defined landslide scarp, suggesting that this area underwent gravitationally deformation but with no separation of the deformed portion from the surrounding area. Three drillcores, to a maximum depth of 96 m, were used during this study, with detailed observations of cut paraffin-impregnated core surfaces used to characterize gravitational deformation in the study area. This logging identified shear zones that consist of disintegrated (brecciated) and pulverized zones that were up to 88 and 19 cm thick, respectively. Disintegrated zone breccias have local jigsaw-fit textures, but other areas contain compositional trails formed by cataclastic flow, and rounded outlines formed by attrition. Pulverized zones underwent increased amounts of shearing, leading to the formation of more rounded fragments and increasing amounts of clayey matrix material, but still containing more than 30% of visible rock fragments. As such, these zones are still classified as breccias in terms of fault rock classification. Planar structures, such as R and Y shears, and P foliations, are not developed in the study area. Shear zones are intermittently located across the slope and have not formed a through-going master sliding zone. Incipient shear zones are present within the slope, including a pair of shear surfaces with a pull apart-like opening, and thin disintegrated or pulverized zones in intact rocks at 3-10 m below the base of the main area of gravitational deformation, suggesting that these shear zones propagate downward in a step-wise manner. This propagation may be related to the redistribution of stress induced by river incision.

  15. High temperature fracturing and ductile deformation during cooling of a pluton: The Lake Edison granodiorite (Sierra Nevada batholith, California)

    NASA Astrophysics Data System (ADS)

    Pennacchioni, Giorgio; Zucchi, Eleonora

    2013-05-01

    In the Bear Creek area of the Sierra Nevada batholith, California, the high temperature postmagmatic deformation structures of the Lake Edison granodiorite include steeply-dipping orthogneiss foliations, joints, and ductile shear zones that nucleated on joints and leucocratic dykes. Exploitation of segmented joints resulted in sharply bounded, thin shear zones and in large slip gradients near the shear zone tips causing the deformation of the host rock at contractional domains. The orthogneiss foliation intensifies towards the contact with the younger Mono Creek granite and locally defines the dextral Rosy Finch Shear Zone (RFSZ), a major kilometre-wide zone crosscutting the pluton contacts. Joints predominantly strike at N70-90°E over most of the Lake Edison pluton and are exploited as sinistral shear zones, both within and outside the RFSZ. In a narrow (˜250 m thick) zone at the contact with the younger Mono Creek granite, within the RFSZ, the Lake Edison granodiorite includes different sets of dextral and sinistral shear zones/joints (the latter corresponding to the set that dominates over the rest of the Lake Edison pluton). These shear zones/joints potentially fit with a composite Y-R-R' shear fracture pattern associated with the RFSZ, or with a pattern consisting of Y-R-shear fractures and rotated T' mode I extensional fractures. The mineral assemblage of shear zones, and the microstructure and texture of quartz mylonites indicate that ductile deformation occurred above 500 °C. Joints and ductile shearing alternated and developed coevally. The existing kinematic models do not fully capture the structural complexity of the area or the spatial distribution of the deformation and magmatic structures. Future models should account more completely for the character of ductile and brittle deformation as these plutons were emplaced and cooled.

  16. Effect of different stages of tensile deformation on micromagnetic parameters in high-strength, low-alloy steel

    SciTech Connect

    Vaidyanathan, S.; Moorthy, V.; Kalyanasundaram, P.; Jayakumar, T.; Raj, B.

    1999-08-01

    The influence of tensile deformation on the magnetic Barkhausen emissions (MBE) and hysteresis loop has been studied in a high-strength, low-alloy steel (HSLA) and its weldment. The magnetic measurements were made both in loaded and unloaded conditions for different stress levels. The root-mean-square (RMS) voltage of the MBE has been used for analysis. This study shows that the preyield and postyield deformation can be identified from the change in the MBE profile. The initial elastic deformation showed a linear increase in the MBE level in the loaded condition, and the MBE level remained constant in the unloaded condition. The microplastic yielding, well below the macroyield stress, significantly reduces the MBE, indicating the operation of grain-boundary dislocation sources below the macroyield stress. This is indicated by the slow increase in the MBE level in the loaded condition and the decrease in the MBE level in the unloaded condition. The macroyielding resulted in a significant increase in the MBE level in the loaded condition and, more clearly, in the unloaded condition. The increase in the MBE level during macroyielding has been attributed to the grain rotation phenomenon, in order to maintain the boundary integrity between adjacent grains, which would preferentially align the magnetic domains along the stress direction. This study shows that MBE during tensile deformation can be classified into four stages: (1) perfectly elastic, (2) microplastic yielding, (3) macroyielding, and (4) progressive plastic deformation. A multimagnetic parameter approach, combining the hysteresis loop and MBE, has been suggested to evaluate the residual stresses.

  17. Deformation of Indian Ocean lithosphere: Evidence for a highly nonlinear rheological law

    NASA Astrophysics Data System (ADS)

    Gordon, Richard G.; Houseman, Gregory A.

    2015-06-01

    The width of diffuse oceanic plate boundaries is determined by the rheology of oceanic lithosphere. Here we apply thin viscous sheet models, which have been successfully applied to deformation in several continental deforming zones, to investigate the deformation of oceanic lithosphere in the diffuse oceanic plate boundaries between the India, Capricorn, and Australia Plates. We apply kinematic boundary conditions based on the current motion between these plates. We neglect buoyancy forces due to plate thinning or thickening and assume that the thin viscous sheet has the same depth-integrated nonlinear viscosity coefficient everywhere. Our initial models have only one adjustable parameter, n, the power-law exponent, with n = 1, 3, 10, 30, and 100. The predicted width of the deforming zone decreases with increasing n, with n ≥ 30 explaining the observations. This n value is higher than has been estimated for continental lithosphere and suggests that more of the strength of oceanic lithosphere lies in layers deforming by faulting or by dislocation glide than for continental lithosphere. To obtain a stress field that better fits the distribution and type of earthquake focal mechanisms in the diffuse oceanic plate boundary, we add a second adjustable parameter, representing the effect of slab pull stretching the oceanic plate near the Sumatra Trench. We show that an average velocity increment on this boundary segment of 5 mm a-1 (relative to the average velocity of the India and Australia Plates) fits the observed distribution of fault types better than velocities of 3.3 mm a-1 or 10 mm a-1.

  18. Deformation of Indian Ocean Lithosphere Implies Highly Non-linear Rheological Law for Oceanic Lithosphere

    NASA Astrophysics Data System (ADS)

    Gordon, Richard; Houseman, Gregory

    2015-04-01

    The width of diffuse oceanic plate boundaries is determined by the rheology of oceanic lithosphere. Here we apply thin viscous sheet models, which have been successfully applied to deformation in several continental deforming zones, to investigate the deformation of oceanic lithosphere in the diffuse oceanic plate boundaries between the India, Capricorn, and Australia plates. We apply kinematic boundary conditions based on the current motion between these plates. We neglect buoyancy forces due to plate thinning or thickening and assume that the thin viscous sheet has the same depth-integrated non-linear viscosity coefficient everywhere. Our initial models have only one adjustable parameter, n, the power-law exponent, with n=1, 3, 10, 30, 100. The predicted width of the deforming zone decreases with increasing n, with n ≥ 30 explaining the observations. This n-value is higher than has been estimated for continental lithosphere, and suggests that more of the strength of oceanic lithosphere lies in layers deforming by faulting or by dislocation glide than for continental lithosphere. To obtain a stress field that better fits the distribution and type of earthquake focal mechanisms in the diffuse oceanic plate boundary, we add a second adjustable parameter, representing the effect of slab-pull stretching the oceanic plate near the Sumatra trench. We show that an average velocity increment on this boundary segment of 5 mm/a (relative to the average velocity of the India and Australia plates) fits the observed distribution of fault types better than velocities of 3.3 mm/a or 10 mm/a.

  19. CONTROL OF LASER RADIATION PARAMETERS: Compensation of dynamic thermal deformations of mirrors in high-power slab lasers

    NASA Astrophysics Data System (ADS)

    Rodionov, A. Yu; Sergeev, V. V.; Smirnov, A. A.; Starovoitov, A. V.; Sherstobitov, V. E.

    2004-11-01

    A system of compensation of thermal deformations of resonator mirrors in high-power CO2 slab lasers based on profiled heating of the mirror back surface is studied theoretically and experimentally. It is shown that such a heating of a resonator mirror makes it possible to minimise dynamic distortions of the output-beam wave front in the case when the lasing power can be varied.

  20. Structure and deformation behavior of Armco iron subjected to severe plastic deformation

    SciTech Connect

    Valiev, R.Z. |; Rauch, E.F.; Baudelet, B.; Ivanisenko, Yu.V.

    1996-12-01

    Structural evolutions in an Armco iron subjected to severe plastic deformation by torsion under high pressure are analyzed with conventional and high resolution electron microscopes. The substructure observed at low strains appears to shrink with increasing deformation and transforms at very high strains into grain boundaries. The resulting grain size decreases down to a constant submicrometric value. Meanwhile, the material strength, as revealed by micro hardness measurements, levels out. Dislocation densities and internal stress levels are used to discuss the structural transformations. Hydrostatic pressure and deformation temperature are believed to modify the steady-state stress level and structural size by impeding the recovery processes involving diffusion.

  1. The formation of supersaturated solid solutions in Fe–Cu alloys deformed by high-pressure torsion

    PubMed Central

    Bachmaier, A.; Kerber, M.; Setman, D.; Pippan, R.

    2012-01-01

    Fully dense bulk nanocomposites have been obtained by a novel two-step severe plastic deformation process in the immiscible Fe–Cu system. Elemental micrometer-sized Cu and Fe powders were first mixed in different compositions and subsequently high-pressure-torsion-consolidated and deformed in a two-step deformation process. Scanning electron microscopy, X-ray diffraction and atom probe investigations were performed to study the evolving far-from-equilibrium nanostructures which were observed at all compositions. For lower and higher Cu contents complete solid solutions of Cu in Fe and Fe in Cu, respectively, are obtained. In the near 50% regime a solid solution face-centred cubic and solid solution body-centred cubic nanograined composite has been formed. After an annealing treatment, these solid solutions decompose and form two-phase nanostructured Fe–Cu composites with a high hardness and an enhanced thermal stability. The grain size of the composites retained nanocrystalline up to high annealing temperatures. PMID:22368454

  2. Equation of state of unreacted high explosives at high pressures

    SciTech Connect

    Yoo, C-S

    1998-08-14

    Isotherms of unreacted high explosives (HMX, RDX, and PETN) have been determined to quasi-hydrostatic high pressures below 45 GPa, by using a diamond-anvil cell angle-resolved synchrotron x-ray diffraction method. The equation-of-state parameters (bulk modulus Bo, and its derivatives B' ) are presented for the 3rd-order Birch-Murnaghan formula based on the measured isotherms. The results are also used to retrieve unreacted Hugoniots in these high explosives and to develop the equations of state and kinetic models for composite high explolsivcs such as XTX-8003 and LX-04. The evidence of shear-induced chemistry of HMX in non-hydrostatic conditions is also presented.

  3. Effects of interface orientation on deformation, mixing, and reaction rates in steady-state and transient shear flows

    NASA Astrophysics Data System (ADS)

    Engdahl, N. B.; Bolster, D.

    2015-12-01

    Reactive transport problems are highly complex and contain a large number of factors that influence the temporal evolution of the system. Physical and chemical heterogeneity, mixing, and even the dimensionality of the system are all known to be important considerations but one important factor that has received comparatively little attention is the initial condition (IC). Oftentimes a single configuration for the IC is selected for a particular study and the other aspects of the problem are varied, but the sensitivity of the problem to perturbations in that IC is not addressed. This work specifically considers how minor changes to the IC affect a mixing limited reactive transport system. A relatively simple flow field is used to investigate changes in global reaction rates for a single, interface-mixing type transport problem. The IC is rotated to several different orientations for the simulations, each having identical reactant masses and initial particle distributions. Reactions are simulated using a Lagrangian, colocation based model that does not assume the reaction system is well mixed. The effects of the rotations on the mixing and reaction rates are variable, manifesting mostly as an increase in product formation relative to pure diffusion, but some configurations inhibit reactions at early times. The orientation of the interface relative to the directions of deformation and the velocity can be used to predict whether reactions rates will increase or decrease, relative to a deformation free flow. The same numerical experiments are then conducted in a transient, periodic shear flow, which exhibits similar results. Both sets of results have implications about how reaction rates should be upscaled and suggest that the configuration of the IC may be as important as proper characterization of the subsurface when considering reactions in complex systems.

  4. Transient deformation induced by groundwater change in Taipei metropolitan area revealed by high resolution X-band SAR interferometry

    NASA Astrophysics Data System (ADS)

    Tung, Hsin; Chen, Horng-Yue; Hu, Jyr-Ching; Ching, Kuo-En; Chen, Hongey; Yang, Kuo-Hsin

    2016-12-01

    We present precise deformation velocity maps for the two year period from September 2011 to July 2013 of the northern Taiwan area, Taipei, by using persistent scatterer interferometry (PSI) technique for processing 18 high resolution X-band synthetic aperture radar (SAR) images archived from COSMO-SkyMed (CSK) constellation. According to the result, the highest subsidence rates are found in Luzou and Wuku area in which the rate is about 15 mm/yr and 10 mm/yr respectively in the whole dataset. However, dramatic change from serve subsidence to uplift in surface deformation was revealed in the Taipei Basin in two different time spans: 2011/09-2012/09 and 2012/09-2013/07. This result shows good agreement with robust continuous GPS measurement and precise leveling survey data across the central Taipei Basin. Moreover, it also represents high correlation with groundwater table. From 8 well data in the Taipei basin, the storativity is roughly constant across most of the aquifer with values between 0.5 × 10- 4 and 1.6 × 10- 3 in Jingmei Formation and 0.8 × 10- 4 and 1.4 × 10- 3 in Wuku Formation. This high correlation indicated that one meter groundwater level change could induce about 9 and 16 mm surface deformation change in Luzou and Wuku area respectively, which is about eight times faster the long-term tectonic deformation rate in this area. Thus, to access the activity of the Shanchiao Fault, it is important to discriminate tectonic movement from anthropogenic or seasonal effect in the Taipei Basin to better understand the geohazards and mitigation in the Taipei metropolitan area.

  5. Mechanisms of plastic deformation in highly cross-linked UHMWPE for total hip components--the molecular physics viewpoint.

    PubMed

    Takahashi, Yasuhito; Shishido, Takaaki; Yamamoto, Kengo; Masaoka, Toshinori; Kubo, Kosuke; Tateiwa, Toshiyuki; Pezzotti, Giuseppe

    2015-02-01

    Plastic deformation is an unavoidable event in biomedical polymeric implants for load-bearing application during long-term in-vivo service life, which involves a mass transfer process, irreversible chain motion, and molecular reorganization. Deformation-induced microstructural alterations greatly affect mechanical properties and durability of implant devices. The present research focused on evaluating, from a molecular physics viewpoint, the impact of externally applied strain (or stress) in ultra-high molecular weight polyethylene (UHMWPE) prostheses, subjected to radiation cross-linking and subsequent remelting for application in total hip arthroplasty (THA). Two different types of commercial acetabular liners, which belong to the first-generation highly cross-linked UHMWPE (HXLPE), were investigated by means of confocal/polarized Raman microprobe spectroscopy. The amount of crystalline region and the spatial distribution of molecular chain orientation were quantitatively analyzed according to a combined theory including Raman selection rules for the polyethylene orthorhombic structure and the orientation distribution function (ODF) statistical approach. The structurally important finding was that pronounced recrystallization and molecular reorientation increasingly appeared in the near-surface regions of HXLPE liners with increasing the amount of plastic (compressive) deformation stored in the microstructure. Such molecular rearrangements, occurred in response to external strains, locally increase surface cross-shear (CS) stresses, which in turn trigger microscopic wear processes in HXLPE acetabular liners. Thus, on the basis of the results obtained at the molecular scale, we emphasize here the importance of minimizing the development of irrecoverable deformation strain in order to retain the pristine and intrinsically high wear performance of HXLPE components.

  6. Long-term High-Quality Deformation Observations near Active Faults in California

    NASA Astrophysics Data System (ADS)

    Agnew, D. C.; Wyatt, F. K.

    2014-12-01

    For monitoring and for improved understanding of the seismic cycle we have collected continuous deformation data close to the two most active faults in Southern California over the past few decades. Pinyon Flat Observatory (PFO) is 14 km from the Anza section of the San Jacinto fault (slip rate 10-15 mm/yr), which has not produced a large earthquake in the past 200 years; Salton City (SCS) is within 15 km of the blind section of the fault further SE. Two locations (Cholame, or CHL, and Durmid Hill, or DHL) are within three km of the San Andreas fault (SAF): CHL, at the N end of the segment that ruptured in 1857, and DHL at the S end of the segment that ruptured about 1700. All these observatories use laser strainmeters (LSM's), 400 to 700 m long, and located on the surface with endpoints anchored 25 m deep. These instruments provide unique long-term high-quality measurements of strain; in geological settings from slightly weathered granite to lake-bed clay sediments, the LSM data record secular strain accumulation consistent with continuous GPS, while covering the temporal range from seismic waves to secular changes. At periods less than a few months, the LSM noise level is far below that from fault-scale GPS networks.The LSM sites near the SAF show strain-rate fluctuations over periods of months and longer of up to 20 percent of the long-term rate, and have also observed aseismic strain events lasting hours to days. At CHL these short-term signals have been observed on borehole strainmeters nearby, and there and at DHL they appear to be a few km deep. Aseismic signals observed at PFO seem to be nearer to the seismogenic zone. In most cases further interpretation has been hampered by not having similar measurements at other locations, but the existing LSM data have been used to rule out possible aseismic strains from nearby earthquake swarms (DHL) and deep tremor (CHL).The LSM data and other measurements at the observatories, confirm how important patience and

  7. Mechanical deformation model of the western United States instantaneous strain-rate field

    USGS Publications Warehouse

    Pollitz, F.F.; Vergnolle, M.

    2006-01-01

    We present a relationship between the long-term fault slip rates and instantaneous velocities as measured by Global Positioning System (GPS) or other geodetic measurements over a short time span. The main elements are the secularly increasing forces imposed by the bounding Pacific and Juan de Fuca (JdF) plates on the North American plate, viscoelastic relaxation following selected large earthquakes occurring on faults that are locked during their respective interseismic periods, and steady slip along creeping portions of faults in the context of a thin-plate system. In detail, the physical model allows separate treatments of faults with known geometry and slip history, faults with incomplete characterization (i.e. fault geometry but not necessarily slip history is available), creeping faults, and dislocation sources distributed between the faults. We model the western United States strain-rate field, derived from 746 GPS velocity vectors, in order to test the importance of the relaxation from historic events and characterize the tectonic forces imposed by the bounding Pacific and JdF plates. Relaxation following major earthquakes (M ??? 8.0) strongly shapes the present strain-rate field over most of the plate boundary zone. Equally important are lateral shear transmitted across the Pacific-North America plate boundary along ???1000 km of the continental shelf, downdip forces distributed along the Cascadia subduction interface, and distributed slip in the lower lithosphere. Post-earthquake relaxation and tectonic forcing, combined with distributed deep slip, constructively interfere near the western margin of the plate boundary zone, producing locally large strain accumulation along the San Andreas fault (SAF) system. However, they destructively interfere further into the plate interior, resulting in smaller and more variable strain accumulation patterns in the eastern part of the plate boundary zone. Much of the right-lateral strain accumulation along the SAF

  8. High energy efficient solid state laser sources

    NASA Technical Reports Server (NTRS)

    Byer, Robert L.

    1987-01-01

    Diode-laser-pumped solid-state laser oscillators and nonlinear processes were investigated. A new generation on nonplanar oscillator was fabricated, and it is anticipated that passive linewidths will be pushed to the kilohertz regime. A number of diode-pumped laser transitions were demonstrated in the rod configuration. Second-harmonic conversion efficiencies as high as 15% are routinely obtained in a servo-locked external resonant doubling crystal at 15 mW cw input power levels at 1064 nm.

  9. Flow Behavior and Microstructural Evolution of 7A85 High-Strength Aluminum Alloy During Hot Deformation

    NASA Astrophysics Data System (ADS)

    Liu, Xingang; Han, Shuang; Chen, Lei; Yang, Shuai; Jin, Miao; Guo, Baofeng; Mao, Tianhong

    2017-02-01

    Hot deformation behavior of 7A85 high-strength aluminum alloy was investigated at 593 K to 713 K (320 °C to 440 °C) and 0.01-10 s-1. The manifestation of flow curves was related to the strain rate. Typical single-peak curves were shown below 10 s-1, while two stress peaks appeared in the case of 10 s-1 and the second peak strain was almost three times larger than the first one. A constitutive equation considering the effect of strain was developed. Flow stress values predicted by the constitutive model demonstrated a good agreement with the experimental results over the entire range of strain rates and temperatures. Microstructure characterization revealed that dynamic recovery (DRV) and continuous dynamic recrystallization (CDRX) which depended on the Zener-Hollomon parameter (Z) closely, co-occurred at large strain (ɛ = 0.7). With decreasing Z-value, the dominant dynamic restoration mechanism gradually transformed from DRV to CDRX. The average subgrain size (d sub) showed a power-law relationship with Z. Recrystallization was sensitively dependent on the strain rate at above 683 K (410 °C). The fine equiaxed grains appeared at original grain boundaries and in deformed grains interior owing to CDRX. The high-curvature subgrain boundaries can also cause the nucleation of recrystallization within deformed grains.

  10. Plastic deformation of high-purity a-titanium: model development and validation using the Taylor cylinder impact test

    NASA Astrophysics Data System (ADS)

    Chandola, Nitin; Revil-Baudard, Benoit; Cazacu, Oana

    2016-08-01

    Results of an experimental study on the quasi-static and high-rate plastic deformation due to impact of a high-purity, polycrystalline, a-titanium material are presented. To quantify the plastic anisotropy and tension-compression asymmetry of the material, first monotonic uniaxial compression and tension tests were carried out at room temperature under quasi-static conditions. It was found that the material is transversely isotropic and displays strong strength differential effects. To characterize the material's strain rate sensitivity, Split Hopkinson Pressure Bar tests in tension and compression were also conducted. Taylor impact tests were performed for impact velocity of 196 m/s. Plastic deformation extended to 64% of the length of the deformed specimen, with little radial spreading. To model simultaneously the observed anisotropy, strain-rate sensitivity, and tension-compression asymmetry of the material, a three-dimensional constitutive model was developed. Key in the formulation is a macroscopic yield function [1] that incorporates the specificities of the plastic flow, namely the combined effects of anisotropy and tension-compression asymmetry. Comparison between model predictions and data show the capabilities of the model to describe with accuracy the plastic behavior of the a-Ti material for both quasi-static and dynamic loadings, in particular, a very good agreement was obtained between the simulated and experimental post-test Taylor specimen geometries.

  11. Application of high resolution geophysical prospecting to assess the risk related to subsurface deformation in Mexico City

    NASA Astrophysics Data System (ADS)

    Centeno-Salas, F. A.; Carreón-Freyre, D.; Flores-García, W. A.; Gutiérrez-Calderón, R. I.

    2015-11-01

    In the eastern sector of Mexico City the sub soil consists of high contrasting sequences (lacustrine and volcanic inter bedded deposits) that favor the development of erratic fracturing in the surface causing damage to the urban infrastructure. The high-resolution geophysical prospecting are useful tools for the assessment of ground deformation and fracturing associated with land subsidence phenomena. The GPR method allowed to evaluate the fracture propagation and deformation of vulcano-sedimentary sequences at different depths, the main electrical parameters are directly related with the gravimetric and volumetric water content and therefore with the plasticity of the near surface prospected sequences. The active seismology prospection consisted in a combination of Seismic Refraction (SR) and Multichannel Analysis of Surface Waves (MASW) for the estimation of the velocity of the mechanical compressive (P) and the shear (S) waves. The integration of both methods allowed to estimate the geomechanical parameters characterizing the studied sequence, the Poisson Ratio and the volumetric compressibility. The obtained mechanical parameters were correlated with laboratory measured parameters such as plasticity index, density, shear strength and compressibility and, GPR and seismic profiles were correlated with the mapped fracture systems in the study area. Once calibrated, the profiles allowed to identify the lithological contact between lacustrine and volcanic sequences, their variations of thicknesses in depth and to assess the deformation area in the surface. An accurate determination of the geometry of fracturing was of the most importance for the assessment of the geological risk in the study area.

  12. How Deformation Behavior Controls Product Performance After Twin Screw Granulation With High Drug Loads and Crospovidone as Disintegrant.

    PubMed

    Meier, Robin; Moll, Klaus-Peter; Krumme, Markus; Kleinebudde, Peter

    2017-01-01

    This study addresses the quantitative influence of 12 different materials (active pharmaceutical ingredients and excipients as surrogate active pharmaceutical ingredients) on the critical quality attributes of twin screw granulated products and subsequently produced tablets. Prestudies demonstrated the significant influence of the chosen model materials (in combination with crospovidone) on the disintegration behavior of the resulting tablets, despite comparable tablet porosities. This study elucidates possible reasons for the varying disintegration behavior by investigating raw material, granule, and tablet properties. An answer could be found in the mechanical properties of the raw materials and the produced granules. Through compressibility studies, the materials could be classified into materials with high compressibility, which deform rather plastically under compression stress, and low compressibility, which display breakages under compression stress. In general, and apart from (pseudo)-polymorphic transformations, brittle materials featured excellent disintegration performance, even at low resulting tablet porosities <8%, whereas plastically deformable materials mostly did not reveal any disintegration. These findings must be considered in the development of simplified formulations with high drug loads, in which the active pharmaceutical ingredient predominantly defines the deformation behavior of the granule.

  13. Time-resolved investigation of nanometer scale deformations induced by a high flux x-ray beam.

    PubMed

    Gaudin, J; Keitel, B; Jurgilaitis, A; Nüske, R; Guérin, L; Larsson, J; Mann, K; Schäfer, B; Tiedtke, K; Trapp, A; Tschentscher, Th; Yang, F; Wulff, M; Sinn, H; Flöter, B

    2011-08-01

    We present results of a time-resolved pump-probe experiment where a Si sample was exposed to an intense 15 keV beam and its surface monitored by measuring the wavefront deformation of a reflected optical laser probe beam. By reconstructing and back propagating the wavefront, the deformed surface can be retrieved for each time step. The dynamics of the heat bump, build-up and relaxation, is followed with a spatial resolution in the nanometer range. The results are interpreted taking into account results of finite element method simulations. Due to its robustness and simplicity this method should find further developments at new x-ray light sources (FEL) or be used to gain understanding on thermo-dynamical behavior of highly excited materials.

  14. Control of focusing in high resolution eye imaging and microscopy using a deformable mirror

    NASA Astrophysics Data System (ADS)

    Costa, Christopher; Rogers, John; Bradu, Adrian; Podoleanu, Adrian

    2013-06-01

    We use a deformable mirror (DM) in an adaptive optics dual channel optical coherence tomography/en-face eye fundus setup to control focus on the sample by adding aberrations to the wavefront. A program was created to sweep the equivalent focus created by the DM. Using this device we are able to sweep the focus between two extremes. This system is also used to measure and monitor any existing aberrations in the system, caused by the optical elements or the target object.

  15. Extended depth-of-field microscopy with a high-speed deformable mirror.

    PubMed

    Shain, William J; Vickers, Nicholas A; Goldberg, Bennett B; Bifano, Thomas; Mertz, Jerome

    2017-03-01

    We present a wide-field fluorescence microscopy add-on that provides a fast, light-efficient extended depth-of-field (EDOF) using a deformable mirror with an update rate of 20 kHz. Out-of-focus contributions in the raw EDOF images are suppressed with a deconvolution algorithm derived directly from the microscope 3D optical transfer function. Demonstrations of the benefits of EDOF microscopy are shown with GCaMP-labeled mouse brain tissue.

  16. Compact high voltage solid state switch

    DOEpatents

    Glidden, Steven C.

    2003-09-23

    A compact, solid state, high voltage switch capable of high conduction current with a high rate of current risetime (high di/dt) that can be used to replace thyratrons in existing and new applications. The switch has multiple thyristors packaged in a single enclosure. Each thyristor has its own gate drive circuit that circuit obtains its energy from the energy that is being switched in the main circuit. The gate drives are triggered with a low voltage, low current pulse isolated by a small inexpensive transformer. The gate circuits can also be triggered with an optical signal, eliminating the trigger transformer altogether. This approach makes it easier to connect many thyristors in series to obtain the hold off voltages of greater than 80 kV.

  17. In situ visualization of magma deformation at high temperature using time-lapse 3D tomography

    NASA Astrophysics Data System (ADS)

    Godinho, jose; Lee, Peter; Lavallee, Yan; Kendrick, Jackie; Von-Aulock, Felix

    2016-04-01

    We use synchrotron based x-ray computed micro-tomography (sCT) to visualize, in situ, the microstructural evolution of magma samples 3 mm diameter with a resolution of 3 μm during heating and uniaxial compression at temperatures up to 1040 °C. The interaction between crystals, melt and gas bubbles is analysed in 4D (3D + time) during sample deformation. The ability to observe the changes of the microstructure as a function of time allow us to: a) study the effect of temperature in the ability of magma to fracture or deform; b) quantify bubble nucleation and growth rates during heating; c) study the relation between crystal displacement and volatile exsolution. We will show unique beautiful videos of how bubbles grow and coalescence, how samples and crystals within the sample fracture, heal and deform. Our study establishes in situ sCT as a powerful tool to quantify and visualize with micro-scale resolution fast processes taking place in magma that are essential to understand ascent in a volcanic conduit and validate existing models for determining the explosivity of volcanic eruptions. Tracking simultaneously the time and spatial changes of magma microstructures is shown to be primordial to study disequilibrium processes between crystals, melt and gas phases.

  18. QPNM calculation for the ground state magnetic moments of odd-mass deformed nuclei: 157-167Er isotopes

    NASA Astrophysics Data System (ADS)

    Yakut, H.; Guliyev, E.; Guner, M.; Tabar, E.; Zenginerler, Z.

    2012-08-01

    A new microscopic method has been developed in the framework of the Quasiparticle-Phonon Nuclear Model (QPNM) in order to investigate spin polarization effects on the magnetic properties such as magnetic moment, intrinsic magnetic moment and effective gs factor of the ground state of odd-mass 157-167Er isotopes. The calculations were performed using both Tamm-Dancoff Approximation (TDA) and Quasiparticle Random-Phase Approximation (QRPA). Reasonably good agreement has been obtained between the QRPA results and the relevant experimental data. Furthermore the variation of the intrinsic magnetic moment gK values with the mass number A exhibits similar behavior for both theoretical and experimental results. From the compression of the calculated intrinsic magnetic moment values with the experimental data the spin-spin interaction parameter has been found as χ=(30/A) MeV for odd-mass 157-167Er isotopes. Our results clarify the possibility of using this new method to describe the magnetic properties of odd-mass deformed nuclei.

  19. Deformed Richardson-Gaudin model

    NASA Astrophysics Data System (ADS)

    Kulish, P.; Stolin, A.; Johannesson, L. H.

    2014-09-01

    The Richardson-Gaudin model describes strong pairing correlations of fermions confined to a finite chain. The integrability of the Hamiltonian allows the algebraic construction of its eigenstates. In this work we show that the quantum group theory provides a possibility to deform the Hamiltonian preserving integrability. More precisely, we use the so-called Jordanian r-matrix to deform the Hamiltonian of the Richardson-Gaudin model. In order to preserve its integrability, we need to insert a special nilpotent term into the auxiliary L-operator which generates integrals of motion of the system. Moreover, the quantum inverse scattering method enables us to construct the exact eigenstates of the deformed Hamiltonian. These states have a highly complex entanglement structure which require further investigation.

  20. Large Deformation Analysis of a High Steep Slope Relating to the Laxiwa Reservoir, China

    NASA Astrophysics Data System (ADS)

    Lin, Peng; Liu, Xiaoli; Hu, Senying; Li, Pujian

    2016-06-01

    The unstable rock slope in the Laxiwa reservoir area of the Yellow River upstream, China, shows the signs of gravitational and water-impounding induced large deformations over an area of 1.15 × 105 m2. Slope movements have been measured daily at more than 560 observation points since 2009, when the reservoir was first impounded. At two of these points, an average daily movement of around 60-80 mm has ever been observed since the beginning of the impounding. Based on the observed deformations and the geology of the site, a fluid-solid coupling model was then adopted to investigate the existing rockslide activity to better understand the mechanism underlying the large deformations. The results from the field observation, kinematic analysis and numerical modeling indicate that the slope instability is dominated by the strong structurally controlled unstable rock mass. Based on an integrated overview of these analyses, a new toppling mode, i.e. the so-called `conjugate block' mode, is proposed to explain the large deformation mechanism of the slope. The conjugate block is formed by a `dumping block' and toppling blocks. The large deformation of the slope is dominated by (1) a toppling component and (2) a subsiding bilinear wedge induced by planar sliding along the deep-seated faults. Following a thorough numerical analysis, it is concluded that small collapses of rock blocks along the slope will be more frequent with the impounding process continuing and the water level fluctuating during the subsequent operation period. Based on a shear strength reduction method and field monitoring, four controlling faults are identified and the instability of the loose structure in the surface layer is analyzed and discussed. The factor of safety against the sliding failure along the deep seated fractures in the slope is 1.72, which reveals that (1) the collapse of the free-standing fractured blocks cannot be ruled out and the volume of the unstable blocks may be greater than 100

  1. High-spin states in ^88Kr

    NASA Astrophysics Data System (ADS)

    Fotiades, N.; Lisetskiy, A. F.; Cizewski, J. A.; Krücken, R.; Clark, R. M.; Fallon, P.; Lee, I. Y.; Macchiavelli, A. O.; Becker, J. A.; Younes, W.

    2007-10-01

    High-spin states in ^88Kr have been studied following the fission of the ^226Th compound nucleus formed in a fusion-evaporation reaction (^18O at 91 MeV on ^208Pb). The Gammasphere array was used to detect γ-ray coincidences. High-spin states up to spin (14^+) and ˜8 MeV excitation energy have been established. The level scheme reported for ^88Kr in the spontaneous fission of ^248Cm [1] has been enriched and extended to higher spin and excitation energies. Differences between the level scheme reported in [1] and that obtained in the present work will be discussed. The observed experimental states are also compared with theoretical shell-model and interacting-boson-model-2 calculations. This work has been supported by the U.S. Department of Energy under Contracts No. DE-AC52-06NA25396 (LANL), W-7405-ENG-48 (LLNL) and AC03-76SF00098 (LBNL) and by the National Science Foundation (Rutgers). [1] T. Rzaca-Urban et al., Eur. Phys. J. A 9, 165 (2000).

  2. High-efficiency solid state power amplifier

    NASA Technical Reports Server (NTRS)

    Wallis, Robert E. (Inventor); Cheng, Sheng (Inventor)

    2005-01-01

    A high-efficiency solid state power amplifier (SSPA) for specific use in a spacecraft is provided. The SSPA has a mass of less than 850 g and includes two different X-band power amplifier sections, i.e., a lumped power amplifier with a single 11-W output and a distributed power amplifier with eight 2.75-W outputs. These two amplifier sections provide output power that is scalable from 11 to 15 watts without major design changes. Five different hybrid microcircuits, including high-efficiency Heterostructure Field Effect Transistor (HFET) amplifiers and Monolithic Microwave Integrated Circuit (MMIC) phase shifters have been developed for use within the SSPA. A highly efficient packaging approach enables the integration of a large number of hybrid circuits into the SSPA.

  3. Short-Term versus Steady-State Crustal Deformation: Are Some Anomalies Driven by Transient Coupling with Mantle Flow? (Invited)

    NASA Astrophysics Data System (ADS)

    Holt, W. E.; Fouch, M. J.; Flesch, L. M.; Klein, E. C.; West, J. D.

    2010-12-01

    An important goal in crustal dynamics studies is the accurate measurement of crustal strain changes over a range of temporal and spatial scales. Measured transients hold the key to quantifying responsible driving forces and processes and the role of crustal and mantle rheological variations. Using GPS velocities, geologic observations, seismically defined crustal thicknesses, and seismic tomography models, we investigate the relationship between the shorter-term geodetic and longer-term ‘steady state’ deformation fields within the Great Basin region of western North America. We first determine a geodetic strain rate field using 4948 GPS velocities from campaign and EarthScope Plate Boundary Observatory stations within western North American Plate Boundary Zone. Details within regions of dense station coverage, such as southern California, show a high-resolution field, with narrow bands of high shear strain rate aligned with the San Andreas and San Jacinto fault zones. We then take the difference tensor field between the geodetic strain rates and those predicted by a crustal dynamic model. The crustal dynamic model possesses internal body forces (topography and crustal thickness variations), lateral strength variations, and spherical cap velocity boundary conditions (Pacific-North America and Juan de Fuca-North America). Furthermore, the crustal dynamic model matches Quaternary rates of strain throughout the plate boundary zone. Differences between the geodetic strain rate tensor field and the dynamic model tensor field can be theoretically related to driving traction rates acting at the base of the lithosphere. Within the Great Basin, we show that there is a negative (contractional) dilatational strain rate anomaly between 115°W - 118°W and 38°N - 40°N. This anomaly overlies a zone where both P and S-wave tomography have revealed a cylindrical volume of higher-than-average mantle velocities that extends from at least the uppermost mantle down to depths of

  4. High tibial osteotomy in medial compartment osteoarthritis and varus deformity using the Taylor spatial frame: early results.

    PubMed

    Robinson, P M; Papanna, M C; Somanchi, B V; Khan, S A

    2011-11-01

    We report the early results of high tibial osteotomy (HTO) in medial compartment osteoarthritis (OA) and varus deformity using the Taylor spatial frame (TSF). Between October 2005 and April 2007, 9 patients with medial compartment OA and varus deformity underwent TSF application and medial opening wedge HTO. Pre- and post-operative Oxford knee scores, SF-12 and visual analogue pain scores were recorded along with radiographic outcomes. Median follow-up was 19 months (range 15-35). Mean age at operation was 49 years (range 37-59). The median time spent in the frame was 18 weeks (range 12-37). The mean preoperative Oxford knee score was 28.7. This improved to a mean of 35.4 post-operatively (P = 0.0142). 6 (67%) patients had a documented pin-site infection. With TKR as an end point, the survival rate of HTOs was 88.9% at a median of 19 months follow-up. This study demonstrates that in selected patients the TSF provides a viable treatment option for performing HTO in medial compartment OA with varus deformity.

  5. High-strength state of ultrafine-grained martensitic steel produced by high pressure torsion

    NASA Astrophysics Data System (ADS)

    Karavaeva, M. V.; Nikitina, M. A.; Ganeev, A. V.; Islamgaliev, R. K.

    2017-02-01

    The paper presents the study results on the effect of severe plastic deformation (SPD) via high pressure torsion (HPT) on the structure and properties of martensitic steel. The contribution of different strengthening mechanisms in the strength of steel has been analyzed. It is shown that independently of the deformation temperature the main contribution in hardening belongs to grain boundaries (about 50 %), whereas the dislocation and solid solution components achieve 15 and 25 %, respectively.

  6. The use of a high-order MEMS deformable mirror in the Gemini Planet Imager

    SciTech Connect

    Poyneer, L A; Bauman, B; Cornelissen, S; Jones, S; Macintosh, B; Palmer, D; Isaacs, J

    2010-12-17

    We briefly review the development history of the Gemini Planet Imager's 4K Boston Micromachines MEMS deformable mirror. We discuss essential calibration steps and algorithms to control the MEMS with nanometer precision, including voltage-phase calibration and influence function characterization. We discuss the integration of the MEMS into GPI's Adaptive Optics system at Lawrence Livermore and present experimental results of 1.5 kHz closed-loop control. We detail mitigation strategies in the coronagraph to reduce the impact of abnormal actuators on final image contrast.

  7. High-precision system identification method for a deformable mirror in wavefront control.

    PubMed

    Huang, Lei; Ma, Xingkun; Bian, Qi; Li, Tenghao; Zhou, Chenlu; Gong, Mali

    2015-05-10

    Based on a mathematic model, the relation between the accuracy of the influence matrix and the performance of the wavefront correction is established. Based on the least squares method, a two-step system identification is proposed to improve the accuracy of the influence matrix, where the measurement noise can be suppressed and the nonlinearity of the deformable mirror can be compensated. The validity of the two-step system identification method is tested in the experiment, where improvements in wavefront correction precision as well as closed-loop control efficiency were observed.

  8. High Speed Solid State Circuit Breaker

    NASA Technical Reports Server (NTRS)

    Podlesak, Thomas F.

    1993-01-01

    The U.S. Army Research Laboratory, Fort Monmouth, NJ, has developed and is installing two 3.3 MW high speed solid state circuit breakers at the Army's Pulse Power Center. These circuit breakers will interrupt 4160V three phase power mains in no more than 300 microseconds, two orders of magnitude faster than conventional mechanical contact type circuit breakers. These circuit breakers utilize Gate Turnoff Thyristors (GTO's) and are currently utility type devices using air cooling in an air conditioned enclosure. Future refinements include liquid cooling, either water or two phase organic coolant, and more advanced semiconductors. Each of these refinements promises a more compact, more reliable unit.

  9. Long-term deformation in the Mississippi Embayment (Central USA) imaged by high-resolution seismic reflection data

    NASA Astrophysics Data System (ADS)

    Hao, Yanjun

    Large magnitude intraplate earthquakes are a puzzling exception to plate tectonic theory. Unlike earthquakes occurring along plate boundaries, large continental intraplate earthquakes are a rare occurrence and are often distributed over broad regions. Albeit rare, their occurrence can cause widespread damage because of the low attenuation of seismic energy typical of plate interiors [Hanks and Johnston, 1992]. In the Central USA, most of the recent tectonic intraplate seismicity concentrates along the New Madrid seismic zone (NMSZ), where three large (M>7) earthquakes occurred between 1811--1812 [Johnston and Schweig, 1996]. Here the low surface deformation rates [Calais and Stein, 2009] conflict with the elevated instrument-recorded seismicity and the occurrence of historical and prehistorical large magnitude events [Tuttle et al., 2002]. One of the promising hypotheses proposed to reconcile this apparent contradiction is that intraplate earthquakes may be temporally clustered, episodic or cyclic, and may migrate spatially at the regional or continental scale across multiple faults or fault systems. In order to test this hypothesis and to understand how and where the long-term deformation is accommodated in the Mississippi Embayment, Central USA, I utilize high-resolution seismic reflection data acquired by the Mississippi River Project [Magnani and McIntosh, 2009] and by a 2010 survey across the Meeman-Shelby fault [Magnani, 2011; Hao et al., 2013]. To identify the location of Quaternary deformation and characterize deformation history, I acquired, processed, and interpreted the seismic reflection data and integrated them with other available geophysical (e.g. seismicity, crustal and lithospheric models) and geological (e.g. magmatism and borehole) data. For my research, I focus on three regions in the Mississippi Embayment: 1) the Meeman-Shelby fault west of Memphis, Tennessee, 2) the eastern Reelfoot rift margin north of Memphis, Tennessee, and 3) the area in

  10. High-spin states in 127I

    NASA Astrophysics Data System (ADS)

    Ding, B.; Zhang, Y. H.; Zhou, X. H.; Dong, G. X.; Xu, F. R.; Liu, M. L.; Li, G. S.; Zhang, N. T.; Wang, H. X.; Zhou, H. B.; Ma, Y. J.; Sasakiz, Y.; Yamada, K.; Ohshima, H.; Yokose, S.; Ishizuka, M.; Komatsubara, T.; Furuno, K.

    2012-04-01

    In-beam γ spectroscopy of the stable nucleus 127I has been studied experimentally using the 124Sn(7Li, 4nγ)127I reaction at a beam energy of 32 MeV. The high-spin level scheme of 127I is extended significantly. Negative-parity levels built on the 11/2-, πh11/2 particle state are observed up to (35/2-) and described as a decoupled band, extending our knowledge of decoupled structures to the most neutron-rich stable iodine isotope. Two ΔI=2 yrast positive-parity sequences are proposed to be associated with the πg7/2 configuration due to observations of several strong interband transitions, and two weakly populated ΔI=2 positive-parity bands are newly identified and interpreted as arising mainly from the πd5/2 configuration. Three-quasiparticle configurations are assigned to the Iπ=15/2+ and 23/2+ states according to the existing knowledge in neighboring nuclei; irregular noncollective and regular collective excitations built on these two (15/2+ and 23/2+) states are observed to coexist at similar energies. The observed three-quasiparticle band structures are further interpreted with the aid of configuration-constrained potential energy surface calculations.

  11. High temperature monotonic and cyclic deformation in a directionally solidified nickel-base superalloy

    NASA Technical Reports Server (NTRS)

    Huron, Eric S.

    1986-01-01

    Directionally solidified (DS) MAR-M246+Hf was tested in tension and fatigue, at temperatures from 20 C to 1093 C. Tests were performed on (001) oriented specimens at strain rates of 50 % and 0.5 % per minute. In tension, the yield strength was constant up to 704 C, above which the strength dropped off rapidly. A strong dependence of strength on strain rate was seen at the higher temperatures. The deformation mode was observed to change from heterogeneous to homogeneous with increasing temperature. Low Cycle Fatigue tests were done using a fully reversed waveform and total strain control. For a given plastic strain range, lives increased with increasing temperature. For a given temperature strain rate had a strong effect on life. At 704 C, decreasing strain rates decreased life, while at the higher temperatures, decreasing strain rates increased life, for a given plastic strain range. These results could be explained through considerations of the deformation modes and stress levels. At the higher temperatures, marked coarsening caused beneficial stress reductions, but oxidation limited the life. The longitudinal grain boundaries were found to influence slip behavior. The degree of secondary slip adjacent to the boundaries was found to be related to the degree of misorientation between the grains.

  12. Effect of thermal treatment on high temperature deformation of alloy Ep-823

    NASA Astrophysics Data System (ADS)

    Lewis, Martin Milburn

    The objective of this research topic is to determine mechanical properties of Alloy EP-823 and to provide a mechanistic understanding of its sensitivity to both thermal treatment and performance temperature. EP-823 is a leading target material for accelerator-driven waste transmutation applications. Overall, the tensile test results of Alloy EP-823 indicated a general trend of decreasing mechanical performance with an increase in tempering time. An increase in tempering time had a statistically significant inverse relationship with ultimate tensile strength (UTS) and yield strength (YS). An increase in tempering time did not have a significant effect on elongation and reduction in area. Performance temperature effects, however, were more noticeable, trending UTS and YS values downward with increasing temperature. Elongation values experience a slight reduction up to 300°C then ramped upwards for increasing temperatures. Reduction of area values appeared unaffected by an increase in temperature up to 400°C but did experience an increase with greater temperatures beyond 400°C. With increasing temperature the mechanical properties changed gradually and predictably up to 400°C, but at 500°C they changed drastically, implying that a critical temperature can be found between 400°C and 500°C. This temperature could be important to design integrity. At performance temperatures beyond this critical temperature the material experiences unstable deformation shortly after reaching the yield strength value, exhibiting severely truncated uniform plastic deformation characteristics.

  13. Fiber feature map based landmark initialization for highly deformable DTI registration.

    PubMed

    Gupta, Aditya; Toews, Matthew; Janardhana, Ravikiran; Rathi, Yogesh; Gilmore, John; Escolar, Maria; Styner, Martin

    2013-03-13

    This paper presents a novel pipeline for the registration of diffusion tensor images (DTI) with large pathological variations to normal controls based on the use of a novel feature map derived from white matter (WM) fiber tracts. The research presented aims towards an atlas based DTI analysis of subjects with considerable brain pathologies such as tumors or hydrocephalus. In this paper, we propose a novel feature map that is robust against variations in WM fiber tract integrity and use these feature maps to determine a landmark correspondence using a 3D point correspondence algorithm. This correspondence drives a deformation field computed using Gaussian radial basis functions(RBF). This field is employed as an initialization to a standard deformable registration method like demons. We present early preliminary results on the registration of a normal control dataset to a dataset with abnormally enlarged lateral ventricles affected by fatal demyelinating Krabbe disease. The results are analyzed based on a regional tensor matching criterion and a visual assessment of overlap of major WM fiber tracts. While further evaluation and improvements are necessary, the results presented in this paper highlight the potential of our method in handling registration of subjects with severe WM pathology.

  14. Tectonic evolution of Ovda Regio: An example of highly deformed continental crust on Venus?

    NASA Astrophysics Data System (ADS)

    Romeo, I.; Capote, R.

    2011-10-01

    A detailed structural analysis of several selected areas of Ovda Regio provides evidence of a complex tectonic evolution. We have reported thrusting in the marginal fold belts indicating together with the presence of short-wavelength folds a significant amount of shortening. Extensional tectonics postdate at least in some locations contraction, while the contrary was not observed. Both contraction and extension occur on a complex layered crust yielding contemporary structures of different wavelengths. The thrust and fold belts of the plateau margins are characterized by concentric contraction followed by concentric contraction with perpendicular extension and finally radial extension. Deformation in the thrust and fold belts of Ovda margins is gradually transmitted to the external plains. A complex tectonic history has been revealed in the internal area of Ovda, basically characterized by contraction in different directions generating basin and dome interference at different wavelengths. Small amounts of a non-coaxial component of deformation have been observed both in the margins and in the central area of the plateau. All the reported observations can be explained if Ovda Regio is a continent that survived a global subduction event.

  15. Correlated states and transparency of a barrier for low-energy particles at monotonic deformation of a potential well with dissipation and a stochastic force

    NASA Astrophysics Data System (ADS)

    Vysotskii, V. I.; Vysotskyy, M. V.

    2014-04-01

    The features of the formation of correlated coherent states of a particle in a parabolic potential well at its monotonic deformation (expansion or compression) in finite limits have been considered in the presence of dissipation and a stochastic force. It has been shown that, in both deformation regimes, a correlated coherent state is rapidly formed with a large correlation coefficient | r| → 1, which corresponds at a low energy of the particle to a very significant (by a factor of 1050-10100 or larger) increase in the transparency of the potential barrier at its interaction with atoms (nuclei) forming the "walls" of the potential well or other atoms located in the same well. The efficiency of the formation of correlated coherent states, as well as | r|, increases with an increase in the deformation interval and with a decrease in the deformation time. The presence of the stochastic force acting on the particle can significantly reduce the maximum | r| value and result in the fast relaxation of correlated coherent states with | r| → 0. The effect of dissipation in real systems is weaker than the action of the stochastic force. It has been shown that the formation of correlated coherent states at the fast expansion of the well can underlie the mechanism of nuclear reactions at a low energy, e.g., in microcracks developing in the bulk of metal hydrides loaded with hydrogen or deuterium, as well as in a low-pressure plasma in a variable magnetic field in which the motion of ions is similar to a harmonic oscillator with a variable frequency.

  16. Application of an ultra-high-resolution FBG strain sensor for crustal deformation measurements at the Aburatsubo Bay, Japan

    NASA Astrophysics Data System (ADS)

    Tokunaga, T.; Liu, Q.; He, Z.; Mogi, K.; Matsui, H.; Wang, H. F.; Kato, T.

    2011-12-01

    For crustal deformation measurements, high-resolution strain sensors on the order of tens of nano-strains are desirable. Current sensors for this purpose include quartz-tube extensometers, free-space laser interferometers, and borehole strainmeters. The former two sensors show quite high strain resolution, however, these are large in size, from tens to hundreds of meter long, and hence, are difficult to measure spatial strain distribution. The optical fiber strain sensors have advantages of multiplexing capability and relatively low cost, and are widely adopted in the applications for structural health monitoring of civil structures such as bridges and buildings. Thus, as long as the strain resolution can be high enough to meet the requirement of crustal deformation measurements, fiber strain sensors can be an attractive tool. We have been developing an ultra-high strain-resolution fiber Bragg grating (FBG) sensor for static strain measurement, interrogated by a narrow line-width tunable laser. The sensor consists of a pair of FBGs, one for strain sensing and the other for temperature compensation. The Bragg wavelength difference between the two FBGs is evaluated using a cross-correlation algorithm. We already demonstrated that an ultra-high resolution corresponding to 2.6 nano-strain was obtained in the case where no strain was applied to the sensor, which was considered to be the ultimate performance of our measurement system. By directly applying variable strains to the developed sensor with a piezo-stage, a resolution of 17.6 nano-strain was demonstrated. This time, the sensor was installed into the vault at Aburatsubo, Japan, to measure crustal deformation caused by ocean tide, and the measured data were compared with the results obtained by a quartz-tube extensometer at the site, which has been measured by the University of Tokyo's Earthquake Research Institute. The deformation induced by oceanic tide was measured by the FBG sensor with the resolution about

  17. Deformability measurement of red blood cells using a microfluidic channel array and an air cavity in a driving syringe with high throughput and precise detection of subpopulations.

    PubMed

    Kang, Yang Jun; Ha, Young-Ran; Lee, Sang-Joon

    2016-01-07

    Red blood cell (RBC) deformability has been considered a potential biomarker for monitoring pathological disorders. High throughput and detection of subpopulations in RBCs are essential in the measurement of RBC deformability. In this paper, we propose a new method to measure RBC deformability by evaluating temporal variations in the average velocity of blood flow and image intensity of successively clogged RBCs in the microfluidic channel array for specific time durations. In addition, to effectively detect differences in subpopulations of RBCs, an air compliance effect is employed by adding an air cavity into a disposable syringe. The syringe was equally filled with a blood sample (V(blood) = 0.3 mL, hematocrit = 50%) and air (V(air) = 0.3 mL). Owing to the air compliance effect, blood flow in the microfluidic device behaved transiently depending on the fluidic resistance in the microfluidic device. Based on the transient behaviors of blood flows, the deformability of RBCs is quantified by evaluating three representative parameters, namely, minimum value of the average velocity of blood flow, clogging index, and delivered blood volume. The proposed method was applied to measure the deformability of blood samples consisting of homogeneous RBCs fixed with four different concentrations of glutaraldehyde solution (0%-0.23%). The proposed method was also employed to evaluate the deformability of blood samples partially mixed with normal RBCs and hardened RBCs. Thereafter, the deformability of RBCs infected by human malaria parasite Plasmodium falciparum was measured. As a result, the three parameters significantly varied, depending on the degree of deformability. In addition, the deformability measurement of blood samples was successfully completed in a short time (∼10 min). Therefore, the proposed method has significant potential in deformability measurement of blood samples containing hematological diseases with high throughput and precise detection of

  18. The Psychosis High-Risk State

    PubMed Central

    Fusar-Poli, Paolo; Borgwardt, Stefan; Bechdolf, Andreas; Addington, Jean; Riecher-Rössler, Anita; Schultze-Lutter, Frauke; Keshavan, Matcheri; Wood, Stephen; Ruhrmann, Stephan; Seidman, Larry J.; Valmaggia, Lucia; Cannon, Tyrone; Velthorst, Eva; De Haan, Lieuwe; Cornblatt, Barbara; Bonoldi, Ilaria; Birchwood, Max; McGlashan, Thomas; Carpenter, William; McGorry, Patrick; Klosterkötter, Joachim; McGuire, Philip; Yung, Alison

    2014-01-01

    Context During the past 2 decades, a major transition in the clinical characterization of psychotic disorders has occurred. The construct of a clinical high-risk (HR) state for psychosis has evolved to capture the prepsychotic phase, describing people presenting with potentially prodromal symptoms. The importance of this HR state has been increasingly recognized to such an extent that a new syndrome is being considered as a diagnostic category in the DSM-5. Objective To reframe the HR state in a comprehensive state-of-the-art review on the progress that has been made while also recognizing the challenges that remain. Data Sources Available HR research of the past 20 years from PubMed, books, meetings, abstracts, and international conferences. Study Selection and Data Extraction Critical review of HR studies addressing historical development, inclusion criteria, epidemiologic research, transition criteria, outcomes, clinical and functional characteristics, neurocognition, neuroimaging, predictors of psychosis development, treatment trials, socioeconomic aspects, nosography, and future challenges in the field. Data Synthesis Relevant articles retrieved in the literature search were discussed by a large group of leading worldwide experts in the field. The core results are presented after consensus and are summarized in illustrative tables and figures. Conclusions The relatively new field of HR research in psychosis is exciting. It has the potential to shed light on the development of major psychotic disorders and to alter their course. It also provides a rationale for service provision to those in need of help who could not previously access it and the possibility of changing trajectories for those with vulnerability to psychotic illnesses. PMID:23165428

  19. Use of a Routh-Russel deformation map to achieve film formation of a latex with a high glass transition temperature.

    PubMed

    Gonzalez, Edurne; Paulis, María; Barandiaran, María Jesús; Keddie, Joseph L

    2013-02-12

    In the film formation of latex, particle deformation can occur by processes of wet sintering, dry sintering, or capillary action. When latex films dry nonuniformly and when particles deform and coalesce while the film is still wet, a detrimental skin layer will develop at the film surface. In their process model, Routh and Russel proposed that the operative particle deformation mechanism can be determined by the values of control parameters on a deformation map. Here, the film formation processes of three methyl methacrylate/butyl acrylate copolymer latexes with high glass transition temperatures (T(g)), ranging from 45 to 64 °C, have been studied when heated by infrared radiation. Adjusting the infrared (IR) power density enables the film temperature, polymer viscosity, and evaporation rate during latex film formation to be controlled precisely. Different polymer particle deformation mechanisms have been demonstrated for the same latex under a variety of film formation process conditions. When the temperature is too high, a skin layer develops. On the other hand, when the temperature is too low, particles deform by dry sintering, and the process requires extended time periods. The deduced mechanisms can be interpreted and explained by the Routh-Russel deformation maps. Film formation of hard (high T(g)) coatings is achieved without using coalescing aids that emit volatile organic compounds (VOCs), which is a significant technical achievement.

  20. An adjoint method for a high-order discretization of deforming domain conservation laws for optimization of flow problems

    NASA Astrophysics Data System (ADS)

    Zahr, M. J.; Persson, P.-O.

    2016-12-01

    The fully discrete adjoint equations and the corresponding adjoint method are derived for a globally high-order accurate discretization of conservation laws on parametrized, deforming domains. The conservation law on the deforming domain is transformed into one on a fixed reference domain by the introduction of a time-dependent mapping that encapsulates the domain deformation and parametrization, resulting in an Arbitrary Lagrangian-Eulerian form of the governing equations. A high-order discontinuous Galerkin method is used to discretize the transformed equation in space and a high-order diagonally implicit Runge-Kutta scheme is used for the temporal discretization. Quantities of interest that take the form of space-time integrals are discretized in a solver-consistent manner. The corresponding fully discrete adjoint method is used to compute exact gradients of quantities of interest along the manifold of solutions of the fully discrete conservation law. These quantities of interest and their gradients are used in the context of gradient-based PDE-constrained optimization. The adjoint method is used to solve two optimal shape and control problems governed by the isentropic, compressible Navier-Stokes equations. The first optimization problem seeks the energetically optimal trajectory of a 2D airfoil given a required initial and final spatial position. The optimization solver, driven by gradients computed via the adjoint method, reduced the total energy required to complete the specified mission nearly an order of magnitude. The second optimization problem seeks the energetically optimal flapping motion and time-morphed geometry of a 2D airfoil given an equality constraint on the x-directed impulse generated on the airfoil. The optimization solver satisfied the impulse constraint to greater than 8 digits of accuracy and reduced the required energy between a factor of 2 and 10, depending on the value of the impulse constraint, as compared to the nominal configuration.

  1. Quaternary Deformation Across the Proterozoic Alabama-Oklahoma Transform Imaged By High-Resolution Seismic Reflection Data

    NASA Astrophysics Data System (ADS)

    Hao, Y.; McIntosh, K. D.; Magnani, M. B.

    2014-12-01

    We hypothesize that Quaternary deformation in the Mississippi Embayment in the Central U.S. has been accommodated by faults additional to the New Madrid seismic zone, and that the location of these faults is strongly controlled by paleotectonic structures inherited from the long tectonic history of the North American continent. To test this hypothesis, a 950 km-long high-resolution multichannel marine seismic reflection section was acquired along the Mississippi River to identify and characterize zones of Quaternary deformation in this region. Here we present three seismic profiles crossing the Alabama-Oklahoma Transform (AOT) that imaged significant faults. The northern profile images multiple faults striking northwest interpreted as the Arkansas River fault zone. The faults offset the reflectors from the tops of Cretaceous to the Eocene Cane River Formation and likely deform Quaternary strata in the upper 20-30 m. The central profile images a down-to-the-north normal fault, displacing the tops of Cretaceous and Paleocene Midway Group units by ~210 m and ~160 m, respectively, interpreted as the northern edge of the Monroe Uplift, a Late Cretaceous uplift caused by igneous intrusions. The southernmost profile shows a down-to-the-south displacement along a south dipping fault, which offsets the tops of the Cretaceous and the Paleocene-Eocene Wilcox Group ~125 m and ~32 m, respectively. Tilted reflectors in the uppermost Eocene and Quaternary strata suggest very recent activity of this fault. The spatial coincidence of the imaged faults with the AOT strongly argues toward a reactivation of this paleotectonic structure in the present stress field. The new seismic data suggest that the AOT is a deformation zone, spanning as wide as ~80 km, that persisted as a weak zone of the lithosphere controlling the location of Tertiary and Quaternary deformation, as demonstrated by dipping reflectors immediately beneath the Mississippi River bottom, earthquake-induced sand blows

  2. Experimental high strain-rate deformation products of carbonate-silicate rocks: Comparison with terrestrial impact materials

    NASA Astrophysics Data System (ADS)

    van der Bogert, C. H.; Schultz, P. H.; Spray, J. G.

    2008-09-01

    Introduction. The response of carbonate to impact processes has thus far been investigated using a combination of thermodynamic modelling, shock experiments, and impact experiments. Localized shear deformation was suggested to play an important role in the failure of carbonate during some shock experiments [1,2], and was invoked to explain significant degassing of carbonates during oblique impact experiments [3]. The results of the impact experiments are at odds with experiments [4] that show back-reaction of CO2 with CaO and MgO could significantly reduce CO2 degassing during impact events. We performed a frictional-welding experiment in order to investigate the effects of high strain-rate deformation on carbonate-silicate target materials, exclusive of shock deformation effects, and to investigate the differing results of other experiments. Samples and Techniques. A frictional melting experiment was performed using dolomitic marble and quartzite samples to simulate conditions during an impact into carbonate-silicate target rocks. The experiment followed the method of Spray (1995) [5]. The 1.5 cm3 samples were mounted onto separate steel cylinders with epoxy. Using a Blacks FWH-3 axial friction-welding rig, the samples were brought into contact at room temperature and under dry conditions with ~5 MPa applied pressure. Contact was maintained for two seconds at 750 rpm for a sustained strain-rate of 102 to 103 s-1. Results. Vapor or fine dust escaped from the interface during the experiment. Immediately after sample separation, the interfaces were incandescent. Once cooled, opaque white material adhered to both the quartzite and dolomitic marble samples. Quartzite sample. Material was injected into cracks that formed in the quartzite sample. Cooling and crystallization of the friction products resulted in the formation of submicron-sized minerals such as periclase and Ca- and Ca,Mg-silicates (Fig. 1) including merwinite and åkermanite. While periclase was observed

  3. High content reduced graphene oxide reinforced copper with a bioinspired nano-laminated structure and large recoverable deformation ability

    PubMed Central

    Xiong, Ding-Bang; Cao, Mu; Guo, Qiang; Tan, Zhanqiu; Fan, Genlian; Li, Zhiqiang; Zhang, Di

    2016-01-01

    By using CuO/graphene-oxide/CuO sandwich-like nanosheets as the building blocks, bulk nacre-inspired copper matrix nano-laminated composite reinforced by molecular-level dispersed and ordered reduced graphene oxide (rGO) with content as high as ∼45 vol% was fabricated via a combined process of assembly, reduction and consolidation. Thanks to nanoconfinement effect, reinforcing effect, as well as architecture effect, the nanocomposite shows increased specific strength and at least one order of magnitude greater recoverable deformation ability as compared with monolithic Cu matrix. PMID:27647264

  4. High content reduced graphene oxide reinforced copper with a bioinspired nano-laminated structure and large recoverable deformation ability

    NASA Astrophysics Data System (ADS)

    Xiong, Ding-Bang; Cao, Mu; Guo, Qiang; Tan, Zhanqiu; Fan, Genlian; Li, Zhiqiang; Zhang, Di

    2016-09-01

    By using CuO/graphene-oxide/CuO sandwich-like nanosheets as the building blocks, bulk nacre-inspired copper matrix nano-laminated composite reinforced by molecular-level dispersed and ordered reduced graphene oxide (rGO) with content as high as ∼45 vol% was fabricated via a combined process of assembly, reduction and consolidation. Thanks to nanoconfinement effect, reinforcing effect, as well as architecture effect, the nanocomposite shows increased specific strength and at least one order of magnitude greater recoverable deformation ability as compared with monolithic Cu matrix.

  5. High-Frequency CTD Measurements for Accurate GPS/acoustic Sea-floor Crustal Deformation Measurement System

    NASA Astrophysics Data System (ADS)

    Tadokoro, K.; Yasuda, K.; Taniguchi, S.; Uemura, Y.; Matsuhiro, K.

    2015-12-01

    The GPS/acoustic sea-floor crustal deformation measurement system has developed as a useful tool to observe tectonic deformation especially at subduction zones. One of the factors preventing accurate GPS/acoustic sea-floor crustal deformation measurement is horizontal heterogeneity of sound speed in the ocean. It is therefore necessary to measure the gradient directly from sound speed structure. We report results of high-frequency CTD measurements using Underway CTD (UCTD) in the Kuroshio region. We perform the UCTD measurements on May 2nd, 2015 at two stations (TCA and TOA) above the sea-floor benchmarks installed across the Nankai Trough, off the south-east of Kii Peninsula, middle Japan. The number of measurement points is six at each station along circles with a diameter of 1.8 nautical miles around the sea-floor benchmark. The stations TCA and TOA are located on the edge and the interior of the Kuroshio current, respectively, judging from difference in sea water density measured at the two stations, as well as a satellite image of sea-surface temperature distribution. We detect a sound speed gradient of high speeds in the southern part and low speeds in the northern part at the two stations. At the TCA station, the gradient is noticeable down to 300 m in depth; the maximum difference in sound speed is +/- 5 m/s. The sound speed difference is as small as +/- 1.3 m/s at depths below 300 m, which causes seafloor benchmark positioning error as large as 1 m. At the TOA station, the gradient is extremely small down to 100 m in depth. The maximum difference in sound speed is less than +/- 0.3 m/s that is negligible small for seafloor benchmark positioning error. Clear gradient of high speed is observed to the depths; the maximum difference in sound speed is +/- 0.8-0.9 m/s, causing seafloor benchmark positioning error of several tens centimeters. The UCTD measurement is effective tool to detect sound speed gradient. We establish a method for accurate sea

  6. High-density, stretchable, all-solid-state microsupercapacitor arrays.

    PubMed

    Hong, Soo Yeong; Yoon, Jangyeol; Jin, Sang Woo; Lim, Yein; Lee, Seung-Jung; Zi, Goangseup; Ha, Jeong Sook

    2014-09-23

    We report on the successful fabrication of stretchable microsupercapacitor (MSC) arrays on a deformable polymer substrate that exhibits high electrochemical performance even under mechanical deformation such as bending, twisting, and uniaxial strain of up to 40%. We designed the deformable substrate to minimize the strain on MSCs by adopting a heterogeneous structure consisting of stiff PDMS islands (on which MSCs are attached) and a soft thin film (mixture of Ecoflex and PDMS) between neighboring PDMS islands. Finite element method analysis of strain distribution showed that an almost negligible strain of 0.47% existed on the PDMS islands but a concentrated strain of 107% was present on the soft thin film area under a uniaxial strain of 40%. The use of an embedded interconnection of the liquid metal Galinstan helped simplify the fabrication and provided mechanical stability under deformation. Furthermore, double-sided integration of MSCs increased the capacitance to twice that of MSCs on a conventional planar deformable substrate. In this study, planar-type MSCs with layer-by-layer assembled hybrid thin film electrodes of MWNT/Mn3O4 and PVA-H3PO4 electrolyte were fabricated; when they are integrated into a circuit, these MSCs increase the output voltage beyond the potential of the electrolyte used. Therefore, various LEDs that require high voltages can be operated under a high uniaxial strain of 40% without any decrease in their brightness. The results obtained in this study demonstrate the high potential of our stretchable MSC arrays for their application as embedded stretchable energy storage devices in bioimplantable and future wearable nanoelectronics.

  7. Texture gradient evolution in Al-5%Ca-5%Zn sheet alloy after tensile deformation at high superplastic strain rate

    SciTech Connect

    Perez-Prado, M.T.; Cristina, M.C.; Torralba, M.; Ruano, O.A.; Gonzalez-Doncel, G.

    1996-12-15

    Texture inhomogeneities have been found in many materials. Given the significant influence of texture in industrial processes like superplastic forming of complex-shaped components, it is important to study the evolution of texture gradients under different testing conditions, particularly at high strain rates. Strong through-thickness texture-gradients have been observed in hot rolled Al alloys. As a consequence of the severe deformation during the hot rolling process, a well defined Brass texture-component (B-orientation) {l_brace}011{r_brace}<211> develops in the mid layer. The Al-5%Ca-5%Zn sheet alloy deforms superplastically when tested uniaxially at temperatures ranging from 350 to 450 C and at strain rates between 10{sup {minus}5}s{sup {minus}1} and 10{sup {minus}2}s{sup {minus}1}. The B-orientation, however, is not present in the texture of the as-rolled material, but it appears after straining in tension along the transverse direction under certain conditions of temperature and moderately high superplastic strain rates. In this work the evolution of the through-thickness texture-gradient in the Al-5%Ca-5% Zn sheet alloy when tested uniaxially in the transverse direction is investigated. Due to the importance of high strain rates in superplastic forming processes, tests at higher strain rates than those usually reported in the literature have been conducted. Current models which predict the appearance of the B-component are criticized on the light of these new findings.

  8. Nanoscale Deformable Optics

    NASA Technical Reports Server (NTRS)

    Strauss, Karl F.; Sheldon, Douglas J.

    2011-01-01

    Several missions and instruments in the conceptual design phase rely on the technique of interferometry to create detectable fringe patterns. The intimate emplacement of reflective material upon electron device cells based upon chalcogenide material technology permits high-speed, predictable deformation of the reflective surface to a subnanometer or finer resolution with a very high degree of accuracy. In this innovation, a layer of reflective material is deposited upon a wafer containing (perhaps in the millions) chalcogenic memory cells with the reflective material becoming the front surface of a mirror and the chalcogenic material becoming a means of selectively deforming the mirror by the application of heat to the chalcogenic material. By doing so, the mirror surface can deform anywhere from nil to nanometers in spots the size of a modern day memory cell, thereby permitting realtime tuning of mirror focus and reflectivity to mitigate aberrations caused elsewhere in the optical system. Modern foundry methods permit the design and manufacture of individual memory cells having an area of or equal to the Feature (F) size of the design (assume 65 nm). Fabrication rules and restraints generally require the instantiation of one memory cell to another no closer than 1.5 F, or, for this innovation, 90 nm from its neighbor in any direction. Chalcogenide is a semiconducting glass compound consisting of a combination of chalcogen ions, the ratios of which vary according to properties desired. It has been shown that the application of heat to cells of chalcogenic material cause a large alteration in resistance to the range of 4 orders of magnitude. It is this effect upon which chalcogenidebased commercial memories rely. Upon removal of the heat source, the chalcogenide rapidly cools and remains frozen in the excited state. It has also been shown that the chalcogenide expands in volume because of the applied heat, meaning that the coefficient of expansion of chalcogenic

  9. Ground state of high-density matter

    NASA Technical Reports Server (NTRS)

    Copeland, ED; Kolb, Edward W.; Lee, Kimyeong

    1988-01-01

    It is shown that if an upper bound to the false vacuum energy of the electroweak Higgs potential is satisfied, the true ground state of high-density matter is not nuclear matter, or even strange-quark matter, but rather a non-topological soliton where the electroweak symmetry is exact and the fermions are massless. This possibility is examined in the standard SU(3) sub C tensor product SU(2) sub L tensor product U(1) sub Y model. The bound to the false vacuum energy is satisfied only for a narrow range of the Higgs boson masses in the minimal electroweak model (within about 10 eV of its minimum allowed value of 6.6 GeV) and a somewhat wider range for electroweak models with a non-minimal Higgs sector.

  10. High spin states in 78Sr

    NASA Astrophysics Data System (ADS)

    Gross, C. J.; Heese, J.; Lieb, K. P.; Lister, C. J.; Varley, B. J.; Chishti, A. A.; McNeill, J. H.; Gelletly, W.

    1989-05-01

    78Sr was produced in the reaction 58Ni(24Mg, 2p2n) with a relative cross section of less than 2.5% of the total fusion cross section at 110 MeV, but high spin states up to 16ħ were firmly identified. Fifteen neutron detectors and fifteen Compton suppressed Ge detectors were used in a large solid angle arrangement. 2nγγ and nγγ coincidences were recorded. A small irregularity in the dynamic moment of inertia J(2)/ħ2 is evidence for a strongly mixed band crossing at ħω~=0.55 MeV in agreement with what is observed in 80,82Sr.

  11. Monitoring of vertical deformations by means high-precision geodetic levelling. Test case: The Arenoso dam (South of Spain)

    NASA Astrophysics Data System (ADS)

    de Lacy, M. Clara; Ramos, M. Isabel; Gil, Antonio J.; Franco, Óscar D.; Herrera, Antonio M.; Avilés, Manuel; Domínguez, Alicia; Chica, Juan Carlos

    2017-03-01

    The Arenoso reservoir is created by an embankment dam, with central clay core, slates and greywacke shoulders. This kind of engineering structure is subject of deformation due to factors such as changes of water level of the reservoir, seat structure, climate changes, etc. In general, dam monitoring involves measurements both outside (external shell) and inside the structure. A number of control points is established around the area of the dam and the measurements of the displacements of the control points take place at several epochs. In this study high-precision levelling techniques have been used to monitor the vertical deformations. In particular five high-precision levelling profiles were measured in five surveys: February and July 2008, March and July 2013 and August 2014. In this study the design, observations and results are presented. On the one hand the results put in evidence the precision of the observations that are always under 1-mm level. On the other hand these results indicate downstream (southeastward) motion of the thrust block center of the dam probably during the fall and winter. The subsidence reachs here the maximum with a value of -14 cm in 2014 (in respect of February 2008). The displacements observed at the berms of the dam exhibit a similar trend to the displacements observed at the crest but they are significantly smaller, as expected. The accumulative vertical displacements and the settlement index indicate the magnitude of the movements decrease in time, confirming the dam tends to stabilize.

  12. General thermostatistical properties of a q-deformed fermion gas in two dimensions

    NASA Astrophysics Data System (ADS)

    Algin, Abdullah; Senay, Mustafa

    2016-10-01

    Starting with a deformed fermionic grand partition function, we study the high and low temperature thermostatistical properties of a special q-deformed fermion gas in two spatial dimensions. Many of the deformed thermostatistical functions such as the specific heat and the entropy are derived in terms of the real deformation parameter q for the range q < 1. For high temperatures, we specifically focus on the behavior of both the entropy function and the deformed virial coefficients in the equation of state for the q-fermion gas in two dimensions. Possible physical applications of the present q-fermion gas are briefly discussed.

  13. Bunionette deformity.

    PubMed

    Cohen, Bruce E; Nicholson, Christopher W

    2007-05-01

    The bunionette, or tailor's bunion, is a lateral prominence of the fifth metatarsal head. Most commonly, bunionettes are the result of a widened 4-5 intermetatarsal angle with associated varus of the metatarsophalangeal joint. When symptomatic, these deformities often respond to nonsurgical treatment methods, such as wider shoes and padding techniques. When these methods are unsuccessful, surgical treatment is based on preoperative radiographs and associated lesions, such as hyperkeratoses. In rare situations, a simple lateral eminence resection is appropriate; however, the risk of recurrence or overresection is high with this technique. Patients with a lateral bow to the fifth metatarsal are treated with a distal chevron-type osteotomy. A widened 4-5 intermetatarsal angle often requires a diaphyseal osteotomy for correction.

  14. Numerical validation of velocity gradient tensor particle tracking velocimetry for highly deformed flow fields

    NASA Astrophysics Data System (ADS)

    Ishikawa, Masa-aki; Murai, Yuichi; Yamamoto, Fujio

    2000-06-01

    Particle tracking velocimetry (PTV) has recently been recognized as quite an effective engineering research tool for understanding multi-dimensional fluid flow structures. There are, however, still a number of unsettled problems in the practical use of PTV, i.e. the lack of generality of the PTV algorithm for various types of flows and the measurement uncertainty with respect to spatial resolution. The authors have developed a generalized PTV algorithm named the velocity gradient tensor (VGT) method in order to accurately track the tracer particles in a flow field with strong local deformation rates. The performance of the VGT method has already been examined for several simple flow fields, such as linear shearing and Taylor-Green vortex flows. In this paper, the applicability of the VGT method for complicated flows, which include a wide dynamic range in wavenumber, is quantitatively examined by simulation of Rankine vortex flows, Karman vortex-shedding flows around a rectangular cylinder and homogeneous turbulent flows, which are numerically solved by using the unsteady Navier-Stokes equations. The results show that the VGT technique, using only two frames to estimate velocity, performs better than does the four-frame PTV technique and has a remarkably higher tracking performance than those of typical conventional PTV algorithms.

  15. High temperature deformation of hot-pressed polycrystalline orthoenstatite. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Dehghan-Banadaki, A.

    1983-01-01

    Artificial hot pressed polycrystalline samples were prepared from purified powder of Bamble, Norway, orthoenstatite, (Mg0.86Fe0.14)SiO3. The uniaxial creep behavior of the polycrystalline orthoenstatite was studied over stress ranges of 10-180 MPa and temperatures of 1500-1700 K (0.82-0.93 T sub m) under two different oxygen fugacities, namely equilibrium (Mo-MoO2 buffer) and a reducing (graphite heating element) atmosphere, respectively. An intergranular glassy phase of different compositions with a cavitational creep deformation were observed. In the Mo-MoO2 buffer atmosphere with PO2 approx. 10 to the minus 11 power - 10 to the minus 13 power atmospheres, the results of an analytical electron microscopy analysis indicate that the glassy phases are richer in Ca and Al due to the residual impurities after hot pressing. In the reducing atmosphere with an oxygen fugacity of PO2 approx. 10 to the minus 3 power - 10 to the minus 25 power atmospheres, the results of analytical electron microscopy analysis indicate that the glassy phase is almost pure silica with the presence of free iron precipitate on grain facets and at triple junctions due to the reduction of bulk materials.

  16. Cyclic Deformation of Advanced High-Strength Steels: Mechanical Behavior and Microstructural Analysis

    NASA Astrophysics Data System (ADS)

    Hilditch, Timothy B.; Timokhina, Ilana B.; Robertson, Leigh T.; Pereloma, Elena V.; Hodgson, Peter D.

    2009-02-01

    The fatigue properties of multiphase steels are an important consideration in the automotive industry. The different microstructural phases present in these steels can influence the strain life and cyclic stabilized strength of the material due to the way in which these phases accommodate the applied cyclic strain. Fully reversed strain-controlled low-cycle fatigue tests have been used to determine the mechanical fatigue performance of a dual-phase (DP) 590 and transformation-induced plasticity (TRIP) 780 steel, with transmission electron microscopy (TEM) used to examine the deformed microstructures. It is shown that the higher strain life and cyclic stabilized strength of the TRIP steel can be attributed to an increased yield strength. Despite the presence of significant levels of retained austenite in the TRIP steel, both steels exhibited similar cyclic softening behavior at a range of strain amplitudes due to comparable ferrite volume fractions and yielding characteristics. Both steels formed low-energy dislocation structures in the ferrite during cyclic straining.

  17. Simulation of high-temperature superlocalization of plastic deformation in single-crystals of alloys with an L12 superstructure

    NASA Astrophysics Data System (ADS)

    Solov'eva, Yu. V.; Fakhrutdinova, Ya. D.; Starenchenko, V. A.

    2015-01-01

    The processes of the superlocalization of plastic deformation in L12 alloys have been studied numerically based on a combination of the model of the dislocation kinetics of the deformation-induced and heat-treatment-induced strengthening of an element of a deformable medium with the model of the mechanics of microplastic deformation described in terms of elastoplastic medium. It has been shown that the superlocalization of plastic deformation is determined by the presence of stress concentrators and by the nonmonotonic strengthening of the elements of the deformable medium. The multiple nonmonotonicity of the process of strengthening of the elementary volume of the medium can be responsible for the multiplicity of bands of microplastic localization of deformation.

  18. Evaluation of high-resolution sea ice models on the basis of statistical and scaling properties of Arctic sea ice drift and deformation

    NASA Astrophysics Data System (ADS)

    Girard, L.; Weiss, J.; Molines, J. M.; Barnier, B.; Bouillon, S.

    2009-08-01

    Sea ice drift and deformation from models are evaluated on the basis of statistical and scaling properties. These properties are derived from two observation data sets: the RADARSAT Geophysical Processor System (RGPS) and buoy trajectories from the International Arctic Buoy Program (IABP). Two simulations obtained with the Louvain-la-Neuve Ice Model (LIM) coupled to a high-resolution ocean model and a simulation obtained with the Los Alamos Sea Ice Model (CICE) were analyzed. Model ice drift compares well with observations in terms of large-scale velocity field and distributions of velocity fluctuations although a significant bias on the mean ice speed is noted. On the other hand, the statistical properties of ice deformation are not well simulated by the models: (1) The distributions of strain rates are incorrect: RGPS distributions of strain rates are power law tailed, i.e., exhibit "wild randomness," whereas models distributions remain in the Gaussian attraction basin, i.e., exhibit "mild randomness." (2) The models are unable to reproduce the spatial and temporal correlations of the deformation fields: In the observations, ice deformation follows spatial and temporal scaling laws that express the heterogeneity and the intermittency of deformation. These relations do not appear in simulated ice deformation. Mean deformation in models is almost scale independent. The statistical properties of ice deformation are a signature of the ice mechanical behavior. The present work therefore suggests that the mechanical framework currently used by models is inappropriate. A different modeling framework based on elastic interactions could improve the representation of the statistical and scaling properties of ice deformation.

  19. Pair-Wise, Deformable Mirror, Image Plane-Based Diversity Electric Field Estimation for High Contrast Coronagraphy

    NASA Technical Reports Server (NTRS)

    Give'on, Amir; Kern, Brian D.; Shaklan, Stuart

    2011-01-01

    In this paper we describe the complex electric field reconstruction from image plane intensity measurements for high contrast coronagraphic imaging. A deformable mirror (DM) surface is modied with pairs of complementary shapes to create diversity in the image plane of the science camera where the intensity of the light is measured. Along with the Electric Field Conjugation correction algorithm, this estimation method has been used in various high contrast imaging testbeds to achieve the best contrasts to date both in narrow and in broad band light. We present the basic methodology of estimation in easy to follow list of steps, present results from HCIT and raise several open quations we are confronted with using this method.

  20. Polymorphism of iron at high pressure: A 3D phase-field model for displacive transitions with finite elastoplastic deformations

    NASA Astrophysics Data System (ADS)

    Vattré, A.; Denoual, C.

    2016-07-01

    A thermodynamically consistent framework for combining nonlinear elastoplasticity and multivariant phase-field theory is formulated at large strains. In accordance with the Clausius-Duhem inequality, the Helmholtz free energy and time-dependent constitutive relations give rise to displacive driving forces for pressure-induced martensitic phase transitions in materials. Inelastic forces are obtained by using a representation of the energy landscape that involves the concept of reaction pathways with respect to the point group symmetry operations of crystal lattices. On the other hand, additional elastic forces are derived for the most general case of large strains and rotations, as well as nonlinear, anisotropic, and different elastic pressure-dependent properties of phases. The phase-field formalism coupled with finite elastoplastic deformations is implemented into a three-dimensional Lagrangian finite element approach and is applied to analyze the iron body-centered cubic (α-Fe) into hexagonal close-packed (ɛ-Fe) phase transitions under high hydrostatic compression. The simulations exhibit the major role played by the plastic deformation in the morphological and microstructure evolution processes. Due to the strong long-range elastic interactions between variants without plasticity, a forward α → ɛ transition is energetically unfavorable and remains incomplete. However, plastic dissipation releases considerably the stored strain energy, leading to the α ↔ ɛ ↔α‧ (forward and reverse) polymorphic phase transformations with an unexpected selection of variants.

  1. Hot deformation characteristics of as-cast high-Cr ultra-super-critical rotor steel with columnar grains

    NASA Astrophysics Data System (ADS)

    Ding, Zong-ye; Hu, Qiao-dan; Zeng, Long; Li, Jian-guo

    2016-11-01

    Isothermal hot compression tests of as-cast high-Cr ultra-super-critical (USC) rotor steel with columnar grains perpendicular to the compression direction were carried out in the temperature range from 950 to 1250°C at strain rates ranging from 0.001 to 1 s-1. The softening mechanism was dynamic recovery (DRV) at 950°C and the strain rate of 1 s-1, whereas it was dynamic recrystallization (DRX) under the other conditions. A modified constitutive equation based on the Arrhenius model with strain compensation reasonably predicted the flow stress under various deformation conditions, and the activation energy was calculated to be 643.92 kJ•mol-1. The critical stresses of dynamic recrystallization under different conditions were determined from the work-hardening rate ( θ)-flow stress ( σ) and -∂ θ/∂ σ-σ curves. The optimum processing parameters via analysis of the processing map and the softening mechanism were determined to be a deformation temperature range from 1100 to 1200°C and a strain-rate range from 0.001 to 0.08 s-1, with a power dissipation efficiency η greater than 31%.

  2. 2D Larkin-Imry-Ma state of deformed ABM phase of superfluid 3He in ``ordered'' aerogel

    NASA Astrophysics Data System (ADS)

    Dmitriev, Vladimir; Senin, Andrey; Yudin, Alexey

    2014-03-01

    We report NMR studies of high temperature superfluid phase of 3He in so called ``ordered'' aerogel1 which strands are almost parallel to each other. Previously, it was found that the NMR properties of this phase depend on whether it is obtained on cooling from the normal phase or on warming from the low temperature phase2. These two types of high temperature phase (called as ESP1 and ESP2) correspond to Anderson-Brinkman-Morel (ABM) phase with large polar distortion and with orbital vector being in 2D Larkin-Imry-Ma (LIM) state. Here we present results which show that the observed difference in NMR signatures of the ESP1 and the ESP2 states is due to that the corresponding 2D LIM states can be anisotropic. In the ESP1 phase the anisotropy is absent or small, while in the ESP2 phase the anisotropy is large. NMR data have allowed us to estimate values of these anisotropies.

  3. High Extraction Phosphors for Solid State Lighting

    SciTech Connect

    Summers, Chris; Menkara, Hisham; Wagner, Brent

    2011-09-01

    We have developed high-index, high efficiency bulk luminescent materials and novel nano-sized phosphors for improved solid-state white LED lamps. These advances can potentially contribute to reducing the loss in luminous efficiencies due to scattering, re-absorption, and thermal quenching. The bulk and nanostructured luminescent materials investigated are index matched to GaN and have broad and size-tunable absorption bands, size and impurity tuned emission bands, size-driven elimination of scattering effects, and a separation between absorption and emission bands. These innovations were accomplished through the use of novel synthesis techniques suitable for high volume production for LED lamp applications. The program produced a full-color set of high quantum yield phosphors with high chemical stability. In the bulk phosphor study, the ZnSeS:Cu,Ag phosphor was optimized to achieve >91% efficiency using erbium (Er) and other activators as sensitizers. Detailed analysis of temperature quenching effects on a large number of ZnSeS:Cu,Ag,X and strontium- and calcium-thiogallate phosphors lead to a breakthrough in the understanding of the anti-quenching behavior and a physical bandgap model was developed of this phenomena. In a follow up to this study, optimized phosphor blends for high efficiency and color performance were developed and demonstrated a 2-component phosphor system with good white chromaticity, color temperature, and high color rendering. By extending the protocols of quantum dot synthesis, large nanocrystals, greater than 20 nm in diameter were synthesized and exhibited bulk-like behavior and blue light absorption. The optimization of ZnSe:Mn nanophosphors achieved ~85% QE The limitations of core-shell nanocrystal systems were addressed by investigating alternative deltadoped structures. To address the manufacturability of these systems, a one-pot manufacturing protocol was developed for ZnSe:Mn nanophosphors. To enhance the stability of these material

  4. Numerical study of the process of plastic deformation localization by an example of high-speed compression of a hollow single crystal cylinder

    NASA Astrophysics Data System (ADS)

    Dmitriev, A. I.; Nikonov, A. Yu.; Bondar', M. P.

    2016-11-01

    The effect of the crystallographic orientation of a single crystal hollow cylinder on features of creation and evolution of plastic deformation in it under conditions of high-speed axisymmetric load is studied. An advantage of the proposed loading scheme is the simultaneous implementation of all loading variants within the chosen crystallographic base plane of the cylinder and reaching different degrees of deformation over the cross section of the sample. Using the molecular-dynamic modeling, the difference in deformation properties of the loaded sample has been shown depending on the chosen crystallographic orientation of the base plane. Results of the investigation can be used to understand the main mechanisms of the plastic deformation of crystalline bodies.

  5. Predissociation of high-lying Rydberg states of molecular iodine via ion-pair states

    SciTech Connect

    Bogomolov, Alexandr S.; Grüner, Barbara; Mudrich, Marcel; Kochubei, Sergei A.; Baklanov, Alexey V.

    2014-03-28

    Velocity map imaging of the photofragments arising from two-photon photoexcitation of molecular iodine in the energy range 73 500–74 500 cm{sup −1} covering the bands of high-lying gerade Rydberg states [{sup 2}Π{sub 1/2}]{sub c}6d;0{sub g}{sup +} and [{sup 2}Π{sub 1/2}]{sub c}6d;2{sub g} has been applied. The ion signal was dominated by the atomic fragment ion I{sup +}. Up to 5 dissociation channels yielding I{sup +} ions with different kinetic energies were observed when the I{sub 2} molecule was excited within discrete peaks of Rydberg states and their satellites in this region. One of these channels gives rise to images of I{sup +} and I{sup −} ions with equal kinetic energy indicating predissociation of I{sub 2} via ion-pair states. The contribution of this channel was up to about 50% of the total I{sup +} signal. The four other channels correspond to predissociation via lower lying Rydberg states giving rise to excited iodine atoms providing I{sup +} ions by subsequent one-photon ionization by the same laser pulse. The ratio of these channels varied from peak to peak in the spectrum but their total ionic signal was always much higher than the signal of (2 + 1) resonance enhanced multi-photon ionization of I{sub 2}, which was previously considered to be the origin of ionic signal in this spectral range. The first-tier E0{sub g}{sup +} and D{sup ′}2{sub g} ion-pair states are concluded to be responsible for predissociation of Rydberg states [{sup 2}Π{sub 1/2}]{sub c}6d;0{sub g}{sup +} and [{sup 2}Π{sub 1/2}]{sub c}6d;2{sub g}, respectively. Further predissociation of these ion-pair states via lower lying Rydberg states gives rise to excited I(5s{sup 2}5p{sup 4}6s{sup 1}) atoms responsible for major part of ion signal. The isotropic angular distribution of the photofragment recoil directions observed for all channels indicates that the studied Rydberg states are long-lived compared with the rotational period of the I{sub 2} molecule.

  6. Application of a new high-speed magnetic deformable mirror for in-vivo retinal imaging

    NASA Astrophysics Data System (ADS)

    Balderas-Mata, Sandra E.; Jones, Steven M.; Zawadzki, Robert J.; Werner, John S.

    2011-08-01

    Nowadays in ophthalmologic practice several commercial instruments are available to image patient retinas in vivo. Many modern fundus cameras and confocal scanning laser ophthalmoscopes allow acquisition of two dimensional en face images of the retina with both back reflected as well as fluorescent light. Additionally, optical coherence tomography systems allow non-invasive probing of three-dimensional retinal morphology. For all of these instruments the available lateral resolution is limited by optical quality of the human eye used as the imaging objective. To improve lateral resolution and achieve diffraction-limited imaging, adaptive optics (AO) can be implemented with any of these imaging systems to correct both static and dynamic aberrations inherent in human eyes. Most of the wavefront correctors used previously in AO systems have limited dynamic range and an insufficient number of actuators to achieve diffraction-limited correction of most human eyes. Thus, additional corrections were necessary, either by trial lenses or additional deformable mirrors (DMs). The UC Davis AO flood-illuminated fundus camera system described in this paper has been previously used to acquire in vivo images of the photoreceptor mosaic and for psychophysical studies on normal and diseased retinas. These results were acquired using a DM manufactured by Litton ITEK (DM109), which has 109 actuators arranged in a hexagonal array below a continuous front-surface mirror. It has an approximate surface actuator stroke of +/-2μm. Here we present results with a new hi-speed magnetic DM manufactured by ALPAO (DM97, voice coil technology), which has 97 actuators and similar inter-actuator stroke (>3μm, mirror surface) but much higher low-order aberration correction (defocus stroke of at least +/-30μm) than the previous one. In this paper we report results of testing performance of the ALPAO DM for the correction of human eye aberrations. Additionally changes made to our AO flood

  7. Comparison between diffraction contrast tomography and high-energy diffraction microscopy on a slightly deformed aluminium alloy.

    PubMed

    Renversade, Loïc; Quey, Romain; Ludwig, Wolfgang; Menasche, David; Maddali, Siddharth; Suter, Robert M; Borbély, András

    2016-01-01

    The grain structure of an Al-0.3 wt%Mn alloy deformed to 1% strain was reconstructed using diffraction contrast tomography (DCT) and high-energy diffraction microscopy (HEDM). 14 equally spaced HEDM layers were acquired and their exact location within the DCT volume was determined using a generic algorithm minimizing a function of the local disorientations between the two data sets. The microstructures were then compared in terms of the mean crystal orientations and shapes of the grains. The comparison shows that DCT can detect subgrain boundaries with disorientations as low as 1° and that HEDM and DCT grain boundaries are on average 4 µm apart from each other. The results are important for studies targeting the determination of grain volume. For the case of a polycrystal with an average grain size of about 100 µm, a relative deviation of about ≤10% was found between the two techniques.

  8. The deformation of B4C particle in the B4C/2024Al composites after high velocity impact.

    PubMed

    Zhou, Zhisong; Wu, Gaohui; Jiang, Longtao; Xu, Zhongguo

    2014-12-01

    In the present work, B4C/2024Al composites with volume fraction of 45% were prepared by a pressure infiltration method. The microstructure of the crater bottom of B4C/2024Al composite after impact was characterized by transmission electron microscope (TEM), which indicated that recovery and dynamic recrystallization generated in Al matrix, and the grain size distribution was about from dozens of nanometer to 200 nm. Furthermore, the plastic deformation was observed in B4C ceramic, which led to the transformation from monocrystal to polycrystal ceramic grains. The boundary observed in this work was high-angle grain boundary and the two grains at the boundary had an orientation difference of 30°.

  9. Structure and microhardness of Al-Si-Cu-Ni alloy after severe plastic deformation and high-temperature annealing

    NASA Astrophysics Data System (ADS)

    Shvets, Karina; Khalikova, Gulnara; Korznikova, Elena; Trifonov, Vadim

    2015-10-01

    The effect of severe plastic deformation by high-pressure torsion (HPT) and subsequent annealing on the microstructure and microhardness of squeeze casting Al-22%Si-3%Cu-1.7%Ni alloy was investigated. HPT was performed at room temperature with 5 rotations under the pressure of 4 GPa. Annealing temperature range varied from 300 to 500°C for 5 min. HPT resulted in refinement and partial dissolution of the primary silicon and intermetallic particles in aluminum matrix and structure fragmentation that caused the microhardness increase. Subsequent annealing lead to the decomposition of the supersaturated solid solution that took place simultaneously with recovery and recrystallization of the fragmented structure. Increase of annealing temperature resulted in decrease of microhardness values.

  10. The effect of environment on the creep deformation of ultra-high purity nickel-chromium-iron alloys at 360 degrees Celcius

    NASA Astrophysics Data System (ADS)

    Paraventi, Denise Jean

    2000-10-01

    Steam generators in pressurized water nuclear power plants have experienced significant problems with intergranular stress corrosion cracking (IGSCC) on the inner diameter of steam generator tubing for over 25 years. In the course of research to understand IGSCC, it has been shown that creep deformation may play a significant role in the cracking of commercial Alloy 600 (Ni-16Cr-9Fe-0.03C). The primary water environment can cause decreases in creep resistance (i.e., faster creep rates, shorter time to failure, and higher creep strains). During corrosion under the conditions of interest, both hydrogen reduction and metal dissolution occur. One or both may contribute to the enhancement of creep. The purpose of this work was to isolate the mechanism by which the water environment causes the creep deformation to increase. Activation area and activation enthalpy for glide were measured in argon and primary water on high purity Ni-16Cr-9Fe alloys. The results indicated that the activation area was reduced by primary water, consistent with a hydrogen enhanced plasticity mechanism for enhanced creep. The stress dependence of creep was also examined in argon and primary water. The results indicated that the internal stress of the alloy is reduced by the primary water environment. Lower internal stress is consistent with both a hydrogen model as well as a vacancy-aided climb model for enhanced creep. To isolate the effect of hydrogen on the creep of the alloy, experiments were conducted in a dissociated hydrogen environment. The results indicated that hydrogen would only increase the steady state creep rate if present before loading of the samples. However, if the sample was already in steady state creep and hydrogen introduced, a transient in the creep strain was observed. The creep rate returned to the original steady state rate in a short time. The results indicate that while hydrogen does affect the steady state creep to an extent, hydrogen cannot completely account for

  11. High temperature deformation of NiAl and CoAl

    NASA Technical Reports Server (NTRS)

    Nix, W. D.

    1982-01-01

    The high temperature mechanical properties of the aluminides are reviewed with respect to their potential as high temperature structural materials. It is shown that NiAl and CoAl are substantially stronger than the pure metals Ni and Co at high temperatures and approach the strength of some superalloys, particularly when those superalloys are tested in "weak" directions. The factors that limit and control the high temperature strengths of NiAl and CoAl are examined to provide a basis for the development of intermetallic alloys of this type.

  12. Effects of vitamin E blending on plastic deformation mechanisms of highly crosslinked ultrahigh molecular weight polyethylene (HXL-UHMWPE) in total hip arthroplasty.

    PubMed

    Takahashi, Yasuhito; Yamamoto, Kengo; Pezzotti, Giuseppe

    2015-03-01

    The molecular mobility and crystalline texture development in highly crosslinked ultrahigh molecular weight polyethylene (HXL-UHMWPE) blended with antioxidant vitamin E (VE, dl-α-tocopherol) were studied via uniaxial compression at room temperature by means of confocal/polarized Raman spectroscopy. The results were compared to morphological analyses under the same compression conditions performed on HXL-UHMWPE prepared in exactly the same way but blending VE into the polyethylene resin (VE-free HXL-UHMWPE). These comparative analyses allow us to evaluate the physical role of VE in morphological alterations of HXL-UHMWPE induced by compression deformation, which can greatly affect its micromechanical behavior. Molecular rearrangement and phase transitions in crystalline and non-crystalline phase, i.e. amorphous and intermediate (third) phase, were found to be part of a reconstruction process after plastic deformation in the samples. Although VE-blended HXL-UHMWPE exhibited more pronounced molecular mobility, as evidenced by its significant deformation-induced texturing, crystallinity change was totally inhibited by the presence of VE during deformation. On the other hand, amorphous-to-intermediate phase transition was confirmed. VE-free HXL-UHMWPE also presented significant crystallization after deformation, but its surface texture evolution occurred to a much lesser extent. This study suggests that the addition of VE induced earlier activation of compression deformation modes in crystalline and non-crystalline phases (e.g. chain slip, interlamellar shear and rotation) due to an increase in polyethylene chain mobility.

  13. Landslide deformation monitoring using point-like target offset tracking with multi-mode high-resolution TerraSAR-X data

    NASA Astrophysics Data System (ADS)

    Shi, Xuguo; Zhang, Lu; Balz, Timo; Liao, Mingsheng

    2015-07-01

    Many landslides in the Three Georges area have shown active deformations associated with water level fluctuations since the full operation of the Three Georges Dam. Such active deformations of landslide bodies need to be closely monitored for disaster prevention and warning. One way to do this is to employ SAR pixel offset tracking, a powerful technique that can be used for measuring two-dimensional large displacements. As an improvement of the original pixel offset tracking technique, the point-like target (PT) offset tracking method focuses on stable point-like targets and thus can obtain more reliable measurements. In this paper, the PT offset tracking method is employed to investigate historical evolution of the Shuping landslide, using time series TerraSAR-X data acquired in both Stripmap (SM) and High-resolution Spotlight (HS) modes. Artificial corner reflectors (CR) installed at/near the landslide are identified as PTs and used to analyze the spatial-temporal pattern of landslide deformations. Results showed that the maximum accumulative deformation of the Shuping landslide reached more than 1.5 m over a time span of two years. A correlation analysis between the deformation trends and the fluctuation of reservoir water level indicated that most deformations of the landslide happened during the water level declining period.

  14. Crustal deformation and gas emission from the Krýsuvík high temperature geothermal system, Iceland

    NASA Astrophysics Data System (ADS)

    Rakel Gudjonsdottir, Sylvia; Ilyinskaya, Evgenia; Hreinsdottir, Sigrun; Michakczewska, Karolina; Bergsson, Baldur; Auippa, Alessandro; Agla Oladottir, Audur; Rut Hjartardottir, Asta

    2016-04-01

    The Krýsuvík volcanic system is located at the oblique spreading Reykjanes Peninsula, Iceland. Since early 2009 the region has been undergoing episodes of localized ground uplift and subsidence. From March 2011 to the end of 2012 the region inflated by over 7 cm, triggering upper crustal earthquakes at the plate boundary. From 2012 to present the region has been subsiding at a relatively steady rate, reaching the pre inflation state by the end of 2015. GPS measurements indicate that the deflation source is located at 3 km depth coinciding with a previously mapped low resistivity zone from MT measurements suggesting the presence of water, magma or conductive minerals. In April 2013, near-real time monitoring of gas emissions started in Krýsuvík using a MultiGAS sensor system to collect data gas composition. Gas emissions are correlated with crustal deformation and seismicity within the Krýsuvík geothermal system. The dataset comprises near-continuous gas composition time series (MultiGAS); quantification of diffuse CO2 gas flux; direct samples of dry gas; seismic records; and GPS dataset. The gas emissions from the Krýsuvík system are H2O dominated with CO2 as the most abundant dry gas species, followed by lesser amounts of H2S. The subsurface equilibrium temperature is calculated as 278°C. This is consistent with previous observations made through sporadical sampling campaigns (e.g. Arnórsson, 1987). In addition, the semi-continuous MultiGAS dataset reveals higher variations of gas composition than previously reported by spot sampling. The diffuse CO2 soil flux is found to be variable between the three degassing areas in Krýsuvík ranging from 10.9-70.9 T/day with the highest flux in Hveradalir where the MultiGAS station is located. The total flux was calculated as 101.4 T/day. Correlation of the MultiGAS data with the geophysical data shows that peaks of H2O-rich emissions follow events of crustal movements. Coinciding with the H2O-rich peaks, SO2 is

  15. 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

    SciTech Connect

    Vignes, Ryan M.; Soules, Thomas F.; Stolken, James S.; Settgast, Randolph R.; Elhadj, Selim; Matthews, Manyalibo J.; 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.

  16. Electronic structures and nonlinear optical properties of highly deformed halofullerenes C(3v) C60F18 and D(3d) C60Cl30.

    PubMed

    Tang, Shu-Wei; Feng, Jing-Dong; Qiu, Yong-Qing; Sun, Hao; Wang, Feng-Di; Chang, Ying-Fei; Wang, Rong-Shun

    2010-11-15

    Electronic structures and nonlinear optical properties of two highly deformed halofullerenes C(3v) C(60)F(18) and D(3d) C(60)Cl(30) have been systematically studied by means of density functional theory. The large energy gaps (3.62 and 2.61 eV) between the highest occupied and lowest unoccupied molecular orbitals (HOMOs and LUMOs) and the strong aromatic character (with nucleus-independent chemical shifts varying from -15.08 to -23.71 ppm) of C(60)F(18) and C(60)Cl(30) indicate their high stabilities. Further investigations of electronic property show that C(60)F(18) and C(60)Cl(30) could be excellent electron acceptors for potential photonic/photovoltaic applications in consequence of their large vertical electron affinities. The density of states and frontier molecular orbitals are also calculated, which present that HOMOs and LUMOs are mainly distributed in the tortoise shell subunit of C(60)F(18) and the aromatic [18] trannulene ring of C(60)Cl(30), and the influence from halogen atoms is secondary. In addition, the static linear polarizability and second-order hyperpolarizability of C(60)F(18) and C(60)Cl(30) are calculated using finite-field approach. The values of and for C(60)F(18) and C(60)Cl(30) molecules are significantly larger than those of C(60) because of their lower symmetric structures and high delocalization of pi electrons.

  17. Spectroscopy of high-lying states in actinide nuclei

    SciTech Connect

    Ahmad, I.; Back, B.B.; Betts, R.R.

    1995-08-01

    In the course of studying positron-electron production during the collisions of uranium beams and tantalum targets, a careful measurement of the emitted gamma radiation was made using large Ge detectors. Many new high energy gamma rays were found, associated both with U-like and Ta-like fragments. To determine the origin of these gamma rays, a dedicated set of improved gamma-ray studies were carried out. The studies used four large (> 55%) Ge detectors mounted in the APEX chamber. States in {sup 238}U and {sup 232}Th were Coulomb excited using a {sup 208}Pb beam of 5.8 MeV/u. Heavy ions were detected in the large-area APEX multiwire proportional counters. The extensive beam monitoring of the APEX setup allowed precise normalization and accurate cross-section determinations. The Doppler shifts from upstream and downstream detectors permitted a precise confirmation of the incident beam energy to less than 0.05 MeV/A. A spectrum of gamma rays, corrected assuming emission from {sup 238}U.

  18. Deformable membranes actuated by high mechanical power density composite electroactive polymers using tailored electric field

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Y.; Bhattacharya, K.

    2003-01-01

    The objective of the project was to develop a versatile electroactuator based on a specific class of EAP, conductive polymer, that is capable of developing high forces and displacements in both bending and linear contraction/expansion movements.

  19. High-speed deformation and fracture of the dioxide-zirconium ceramics and zirconium alumina concrete

    NASA Astrophysics Data System (ADS)

    Bragov, A.; Kruszka, L.; Lomunov, A.; Konstantinov, A.; Lamzin, D.; Filippov, A.

    2012-08-01

    The results of dynamic tests of two refractory materials based on zirconium dioxide: three types of ceramics and barium-aluminate concrete. The ceramic specimens had various initial density and porosity and also differed by technology of manufacturing. Compression tests were carried out using the Kolsky technique and its updating - specimen in a rigid jacket. The dynamic stress-strain curves were obtained. The strong influence of sample's initial grain composition, mode of stressed-strained state and technologies of manufacturing of specimens onto ceramics mechanical properties is marked.

  20. On The Creep Behavior and Deformation Mechanisms Found in an Advanced Polycrystalline Nickel-Base Superalloy at High Temperatures

    NASA Astrophysics Data System (ADS)

    Deutchman, Hallee Zox

    Polycrystalline Ni-base superalloys are used as turbine disks in the hot section in jet engines, placing them in a high temperature and stress environment. As operating temperatures increase in search of better fuel efficiency, it becomes important to understand how these higher temperatures are affecting mechanical behavior and active deformation mechanisms in the substructure. Not only are operating temperatures increasing, but there is a drive to design next generation alloys in shorter time periods using predictive modeling capabilities. This dissertation focuses on mechanical behavior and active deformation mechanisms found in two different advanced polycrystalline alloy systems, information which will then be used to build advanced predictive models to design the next generation of alloys. The first part of this dissertation discusses the creep behavior and identifying active deformation mechanisms in an advanced polycrystalline Ni-based superalloy (ME3) that is currently in operation, but at higher temperatures and stresses than are experienced in current engines. Monotonic creep tests were run at 700°C and between 655-793MPa at 34MPa increments, on two microstructures (called M1 and M2) produced by different heat treatments. All tests were crept to 0.5% plastic strain. Transient temperature and transient stress tests were used determine activation energy and stress exponents of the M1 microstructure. Constant strain rate tests (at 10-4s-1) were performed on both microstructures as well. Following creep testing, both M1 and M2 microstructures were fully characterized using Scanning Electron Microscopy (SEM) for basic microstructure information, and Scanning Transmission Electron Microscopy (STEM) to determine active deformation mechanism. It was found that in the M1 microstructure, reorder mediated activity (such as discontinuous faulting and microtwinning) is dominant at low stresses (655-724 MPa). Dislocations in the gamma matrix, and overall planar

  1. ‘Sausage-string’ deformations of blood vessels at high blood pressures

    NASA Astrophysics Data System (ADS)

    Alstrøm, P.; Mikkelsen, R.; Gustafsson, F.; Holstein-Rathlou, N.-H.

    1999-12-01

    A new instability is proposed to explain the ‘sausage-string’ patterns of alternating constrictions and dilatations formed in blood vessels at high blood pressure conditions. Our theory provides predictions for the conditions under which the cylindrical geometry of a blood vessel becomes unstable. The theory is related to experimental observations in rats, where high blood pressure is induced by intravenous infusion of angiotensin II.

  2. Implementation of an Associative Flow Rule Including Hydrostatic Stress Effects Into the High Strain Rate Deformation Analysis of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Roberts, Gary D.; Gilat, Amos

    2003-01-01

    A previously developed analytical formulation has been modified in order to more accurately account for the effects of hydrostatic stresses on the nonlinear, strain rate dependent deformation of polymer matrix composites. State variable constitutive equations originally developed for metals have been modified in order to model the nonlinear, strain rate dependent deformation of polymeric materials. To account for the effects of hydrostatic stresses, which are significant in polymers, the classical J2 plasticity theory definitions of effective stress and effective inelastic strain, along with the equations used to compute the components of the inelastic strain rate tensor, are appropriately modified. To verify the revised formulation, the shear and tensile deformation of two representative polymers are computed across a wide range of strain rates. Results computed using the developed constitutive equations correlate well with experimental data. The polymer constitutive equations are implemented within a strength of materials based micromechanics method to predict the nonlinear, strain rate dependent deformation of polymer matrix composites. The composite mechanics are verified by analyzing the deformation of a representative polymer matrix composite for several fiber orientation angles across a variety of strain rates. The computed values compare well to experimentally obtained results.

  3. Stress Localization and Kinking as a Potential Source of Rheological Weakening in the High-Stress Deformation of Polycrystalline Ice

    NASA Astrophysics Data System (ADS)

    Prior, D. J.; Seidemann, M.; Golding, N.; Durham, W. B.; Vaughan, M. J.

    2015-12-01

    Constraining water ice rheology is crucial for geodynamic modelling of terrestrial ice masses and to understand the mechanics of icy planets in the outer solar system. Creep experiments on homogenous laboratory-grown ice have been conducted for decades with the goal to link specific stress and temperature conditions to creep (strain) rates, which are governed by the operating microstructural deformation mechanism. As most of these experiments have been conducted under constant strain rate conditions and in the absence of a time-effective method to image fine-grained ice, the response of an ice microstructure to a constant stress experiment is fairly unknown. In this study, 25 mm diameter cylinders of polycrystalline ice with a starting average grain diameter of 400 μm were subjected to a confining pressure of 50 MPa and axial loads between 3 and 13 MPa at a temperature of 240 K. The samples were subsequently imaged with cryogenic electron backscatter diffraction (cryo-EBSD). Over the entire range of these tests, constantly accelerating strain rates were observed, which represent a significant rheological weakening. Microstructural maps of the deformed ice samples show stress localizations that are characterized by excessive kinking, leading to a "crushed" appearance of pre-existing grains. The localized kinking can produce grain diameters as small as 30 µm and yields a local grain size reduction that could provide an explanation for the rheological weakening, as observed in the accelerating strain rates. A detailed microstructural analysis aims to investigate the mechanism of kinking in these stress localizations with a microstructural misorientation analysis comprising both pre-existing and kinked grains. Grain size data collected from within the high-stress regions will be compared to pre-existing rheological data to assess if the localized grain size reduction could in fact result in the observed accelerations in strain rate.

  4. Arbitrarily Curved and Twisted Space Beams. Ph.D. Thesis - Va. Polytech. Inst. and State Univ.; [Elastic Deformation, Stress Analysis

    NASA Technical Reports Server (NTRS)

    Hunter, W. F.

    1974-01-01

    A derivation of the equations which govern the deformation of an arbitrarily curved and twisted space beam is presented. These equations differ from those of the classical theory in that (1) extensional effects are included; (2) the strain-displacement relations are derived; and (3) the expressions for the stress resultants are developed from the strain displacement relations. It is shown that the torsional stress resultant obtained by the classical approach is basically incorrect except when the cross-section is circular. The governing equations are given in the form of first-order differential equations. A numerical algorithm is given for obtaining the natural vibration characteristics and example problems are presented.

  5. High energy efficient solid state laser sources

    NASA Technical Reports Server (NTRS)

    Byer, Robert L.

    1989-01-01

    Recent progress in the development of highly efficient coherent optical sources was reviewed. This work has focused on nonlinear frequency conversion of the highly coherent output of the non-planar ring laser oscillators developed earlier in the program, and includes high efficiency second harmonic generation and the operation of optical parametric oscillators for wavelength diversity and tunability.

  6. High energy efficient solid state laser sources

    NASA Technical Reports Server (NTRS)

    Byer, Robert L.

    1988-01-01

    Recent progress in the development of highly efficient coherent optical sources is reviewed. This work focusses on nonlinear frequency conversion of the highly coherent output of the Non-Planar Ring Laser Oscillators developed earlier in the program, and includes high efficiency second harmonic generation and the operation of optical parametric oscillators for wavelength diversity and tunability.

  7. High Temperature Monotonic and Cyclic Deformation in a Directionally Solidified Nickel-Base Superalloy.

    DTIC Science & Technology

    1986-05-01

    34Metallurgical Aspects of High Temperature Fatigue." Fatigue des Materiaux et des Structures. C. Bathias and J. P. Bailon, editors (1978). 5. S. D. Antolovich...hinge. A spring steel loop was wound around the top extensometer rod for attachment of the extensometer suspension cord, and two more spring steel

  8. Microstructural Characteristics of High Rate Plastic Deformation in Elektron (trademark) WE43 Magnesium Alloy

    DTIC Science & Technology

    2012-04-01

    Mordike T. Ebert, "Magnesium Properties - applications - potential," Materials Science and Engineering A, vol. 302, no. 1, pp. 37-45, 2001. [2...boundary sliding in rolled AZ91 magnesium alloy at high strain rates," Materials Science and Engineering A, vol. 360, no. 1-2, pp. 107-115,2003

  9. Microstructural evolution in a ferritic-martensitic stainless steel and its relation to high-temperature deformation and rupture models

    SciTech Connect

    DiMelfi, R.J.; Gruber, E.E.; Kramer, J.M.

    1991-01-01

    The ferritic-martensitic stainless steel HT-9 exhibits an anomalously high creep strength in comparison to its high-temperature flow strength from tensile tests performed at moderate rates. A constitutive relation describing its high-temperature tensile behavior over a wide range of conditions has been developed. When applied to creep conditions the model predicts deformation rates orders of magnitude higher than observed. To account for the observed creep strength, a fine distribution of precipitates is postulated to evolve over time during creep. The precipitate density is calculated at each temperature and stress to give the observed creep rate. The apparent precipitation kinetics thereby extracted from this analysis is used in a model for the rupture-time kinetics that compares favorably with observation. Properly austenitized and tempered material was aged over times comparable to creep conditions, and in a way consistent with the precipitation kinetics from the model. Microstructural observations support the postulates and results of the model system. 16 refs., 10 figs.

  10. High power diode and solid state lasers

    NASA Astrophysics Data System (ADS)

    Eichler, H. J.; Fritsche, H.; Lux, O.; Strohmaier, S. G.

    2017-01-01

    Diode lasers are now basic pump sources of crystal, glass fiber and other solid state lasers. Progress in the performance of all these lasers is related. Examples of recently developed diode pumped lasers and Raman frequency converters are described for applications in materials processing, Lidar and medical surgery.

  11. Spinal deformity.

    PubMed

    Bunnell, W P

    1986-12-01

    Spinal deformity is a relatively common disorder, particularly in teenage girls. Early detection is possible by a simple, quick visual inspection that should be a standard part of the routine examination of all preteen and teenage patients. Follow-up observation will reveal those curvatures that are progressive and permit orthotic treatment to prevent further increase in the deformity. Spinal fusion offers correction and stabilization of more severe degrees of scoliosis.

  12. Comparison of Deformation in High-Purity Single/Large Grain and Polycrystalline Niobium Superconducting Cavities

    SciTech Connect

    Ganapati Rao Myneni; Peter Kneisel

    2005-07-10

    The current approach for the fabrication of superconducting radio frequency (SRF) cavities is to roll and deep draw sheets of polycrystalline high-purity niobium. Recently, a new technique was developed at Jefferson Laboratory that enables the fabrication of single-crystal high-purity Nb SRF cavities. To better understand the differences between SRF cavities fabricated out of fine-grained polycrystalline sheet in the standard manner and single crystal cavities fabricated by the new technique, two half-cells were produced according to the two different procedures and compared using a variety of analytical techniques including optical microscopy, scanning laser confocal microscopy, profilometry, and X-ray diffraction. Crystallographic orientations, texture, and residual stresses were determined in the samples before and after forming and this poster presents the results of this ongoing study.

  13. Creep deformation of grain boundary in a highly crystalline SiC fibre.

    PubMed

    Shibayama, Tamaki; Yoshida, Yutaka; Yano, Yasuhide; Takahashi, Heishichiro

    2003-01-01

    Silicon carbide (SiC) matrix composites reinforced by SiC fibres (SiC/SiC composites) are currently being considered as alternative materials in high Ni alloys for high-temperature applications, such as aerospace components, gas-turbine energy-conversion systems and nuclear fusion reactors, because of their high specific strength and fracture toughness at elevated temperatures compared with monolithic SiC ceramics. It is important to evaluate the creep properties of SiC fibres under tensile loading in order to determine their usefulness as structural components. However, it would be hard to evaluate creep properties by monoaxial tensile properties when we have little knowledge on the microstructure of crept specimens, especially at the grain boundary. Recently, a simple fibre bend stress relaxation (BSR) test was introduced by Morscher and DiCarlo to address this problem. Interpretation of the fracture mechanism at the grain boundary is also essential to allow improvement of the mechanical properties. In this paper, effects of stress applied by BSR test on microstructural evolution in advanced SiC fibres, such as Tyranno-SA including small amounts of Al, are described and discussed along with the results of microstructure analysis on an atomic scale by using advanced microscopy.

  14. Stability of the high-density ferromagnetic ground state of a chargeless, magnetic-dipolar, quantum Fermi liquid.

    PubMed

    Mahanti, S D; Jha, Sudhanshu S

    2007-12-01

    We obtain the best upper bound for the ground-state energy of a system of chargeless fermions of mass m, spin s=1/2 , and magnetic moment mus[over ] as a function of its density in the fully spin-polarized Hartree-Fock determinantal state, specified by a prolate spheroidal plane-wave single-particle occupation function n_(k[over ]) , by minimizing the total energy E at each density with respect to the variational spheroidal deformation parameter beta(2),0< or =beta(2)< or =1 . We find that at high densities, this spheroidal ferromagnetic state is the most likely ground state of the system, but it is still unstable towards the infinite-density collapse. This optimized ferromagnetic state is shown to be a stable ground state of the dipolar system at high densities, if one has an additional repulsive short-range hardcore interaction of sufficient strength and nonvanishing range.

  15. High-spin states in 208Rn

    NASA Astrophysics Data System (ADS)

    Triggs, W. J.; Poletti, A. R.; Dracoulis, G. D.; Fahlander, C.; Byrne, A. P.

    1983-03-01

    The yrast decay scheme of 208Rn has been investigated up to spin ≈ 20 h̵ and an excitation energy of ≈ 6 MeV. Several different γ-ray spectroscopic techniques were used to determine the properties of excited states and transitions in the nucleus. Significant changes to the previously established level scheme are proposed, based on the existence of an unobserved 3.1 keV transition. Simple empirical shell-model calculations of level energies aided in the assignment of shell-model configurations to excited states and the decay scheme is discussed in terms of these configurations. The energy level systematics for the even radon isotopes, from A = 206 to 212 are discussed, as are core polarization effects in the even radon isotopes ( A = 204 to 210) and polonium isotopes ( A = 202-208).

  16. High energy efficient solid state laser sources

    NASA Technical Reports Server (NTRS)

    Byer, Robert L.

    1987-01-01

    Investigations continue of diode-laser-pumped solid-state laser oscillators and nonlinear processes using them as sources. Diode laser array pumped Nd:YAG and Nd:glass lasers have been demonstrated. Theoretical studies of non-planar oscillators have been advanced, producing new designs which should be more resistant to feedback and offer better frequency stability. A monolithic, singly resonant Optical Parametric Oscillator in MgO:LiNbO3 has been operated.

  17. A High-Rate Continuous GPS Network in Iceland for Crustal Deformation Research

    NASA Astrophysics Data System (ADS)

    Geirsson, H.; Árnadóttir, T.; Bennett, R.; Lafemina, P.; Jónsson, S.; Hreinsdóttir, S.; Holland, A.; Deutscher, J.; Ingvarsson, T.; Sturkell, E.; Villemin, T.

    2007-12-01

    A significant expansion of the current continuous GPS network in Iceland is well underway. The goal of the project is to install 30-40 new continuous GPS stations, with a sampling rate of 1 second or higher in selected areas of the country. Most of the sites are already installed and are collecting data and communications are being established. Currently we have in total about 50 continuous and 12 semi-continuous stations running. Eventually, the older continuous GPS stations (installed from 1999 onwards) will also be upgraded to allow high sampling rates. Many of the CGPS sites are co-located with stations in the national seismic network which is very beneficial for operation of the sites and enhanced monotoring capabilities. The national seismic network in Iceland contains 51 3-component digital stations that all are on-line. High-rate GPS observations have been used successfully to study dynamic earthquake rupture processes, for example the Denali earthquake in Alaska and the 2003 Tokachi-Oki earthquake in Japan. New GPS stations were installed in seismically active areas in the South Iceland Seismic Zone, the Reykjanes Peninsula and in Northern Iceland. We also attempt to capture volcanic processes by installing high-rate GPS stations near the three most active volcanoes in Iceland: Hekla, Grímsvotn, and Katla. These volcanoes have been active recently or are currently showing signs of unrest. Continuous GPS and recent campaign GPS measurements indicate rapid uplift (up to 2 cm/yr) over a wide area in central Iceland due to retreat of the glaciers in a warming climate. The new network already installed in central Iceland will obtain more detailed information on the rate and extent of the uplift. Implementing the 1-Hz technology in Iceland enables studies of both the dynamic as well as slower-rate processes related to earthquake and volcanic activity. The high level of volcanic and earthquake activity in Iceland makes it an ideal site for this project. In

  18. Simultaneous X-ray diffraction and phase-contrast imaging for investigating material deformation mechanisms during high-rate loading

    PubMed Central

    Hudspeth, M.; Sun, T.; Parab, N.; Guo, Z.; Fezzaa, K.; Luo, S.; Chen, W.

    2015-01-01

    Using a high-speed camera and an intensified charge-coupled device (ICCD), a simultaneous X-ray imaging and diffraction technique has been developed for studying dynamic material behaviors during high-rate tensile loading. A Kolsky tension bar has been used to pull samples at 1000 s−1 and 5000 s−1 strain-rates for super-elastic equiatomic NiTi and 1100-O series aluminium, respectively. By altering the ICCD gating time, temporal resolutions of 100 ps and 3.37 µs have been achieved in capturing the diffraction patterns of interest, thus equating to single-pulse and 22-pulse X-ray exposure. Furthermore, the sample through-thickness deformation process has been simultaneously imaged via phase-contrast imaging. It is also shown that adequate signal-to-noise ratios are achieved for the detected white-beam diffraction patterns, thereby allowing sufficient information to perform quantitative data analysis diffraction via in-house software (WBXRD_GUI). Of current interest is the ability to evaluate crystal d-spacing, texture evolution and material phase transitions, all of which will be established from experiments performed at the aforementioned elevated strain-rates. PMID:25537588

  19. Simultaneous X-ray diffraction and phase-contrast imaging for investigating material deformation mechanisms during high-rate loading

    SciTech Connect

    Hudspeth, M.; Sun, T.; Parab, N.; Guo, Z.; Fezzaa, K.; Luo, S.; Chen, W.

    2015-01-01

    Using a high-speed camera and an intensified charge-coupled device (ICCD), a simultaneous X-ray imaging and diffraction technique has been developed for studying dynamic material behaviors during high-rate tensile loading. A Kolsky tension bar has been used to pull samples at 1000 s-1and 5000 s-1strain-rates for super-elastic equiatomic NiTi and 1100-O series aluminium, respectively. By altering the ICCD gating time, temporal resolutions of 100 ps and 3.37 µs have been achieved in capturing the diffraction patterns of interest, thus equating to single-pulse and 22-pulse X-ray exposure. Furthermore, the sample through-thickness deformation process has been simultaneously imagedviaphase-contrast imaging. It is also shown that adequate signal-to-noise ratios are achieved for the detected white-beam diffraction patterns, thereby allowing sufficient information to perform quantitative data analysis diffractionviain-house software (WBXRD_GUI). Of current interest is the ability to evaluate crystald-spacing, texture evolution and material phase transitions, all of which will be established from experiments performed at the aforementioned elevated strain-rates.

  20. A viable circulating tumor cell isolation device with high retrieval efficiency using a reversibly deformable membrane barrier

    NASA Astrophysics Data System (ADS)

    Kim, Yoonji; Bu, Jiyoon; Cho, Young-Ho; Son, Il Tae; Kang, Sung-Bum

    2017-02-01

    Circulating tumor cells (CTCs) contain prognostic information of the tumor, since they shed from the primary tumor and invade into the bloodstream. Therefore, the viable isolation is necessary for a consequent analysis of CTCs. Here, we present a device for the viable isolation and efficient retrieval of CTCs using slanted slot filters, formed by a reversibly deformable membrane barrier. Conventional filters have difficulties in retrieving captured cells, since they easily clog the slots. Moreover, large stress concentration at the sharp edges of squared slots, causes cell lysis. In contrast, the present device shows over 94% of high retrieval efficiency, since the slots can be opened simply by relieving the pressure. Furthermore, the inflated membrane barrier naturally forms the slanted slots, thus reducing the cell damage. By using cancer cell lines, we verified that the present device successfully isolate targeted cells, even at an extremely low concentrations (~10 cells/0.1 ml). In the clinical study, 85.7% of patients initially showed CTC positive while the numbers generally decreased after the surgery. We have also proved that the number of CTCs were highly correlated with tumour invasiveness. Therefore, the present device has potential for use in cancer diagnosis, surgical validation, and invasiveness analysis.

  1. Simultaneous X-ray diffraction and phase-contrast imaging for investigating material deformation mechanisms during high-rate loading.

    PubMed

    Hudspeth, M; Sun, T; Parab, N; Guo, Z; Fezzaa, K; Luo, S; Chen, W

    2015-01-01

    Using a high-speed camera and an intensified charge-coupled device (ICCD), a simultaneous X-ray imaging and diffraction technique has been developed for studying dynamic material behaviors during high-rate tensile loading. A Kolsky tension bar has been used to pull samples at 1000 s(-1) and 5000 s(-1) strain-rates for super-elastic equiatomic NiTi and 1100-O series aluminium, respectively. By altering the ICCD gating time, temporal resolutions of 100 ps and 3.37 µs have been achieved in capturing the diffraction patterns of interest, thus equating to single-pulse and 22-pulse X-ray exposure. Furthermore, the sample through-thickness deformation process has been simultaneously imaged via phase-contrast imaging. It is also shown that adequate signal-to-noise ratios are achieved for the detected white-beam diffraction patterns, thereby allowing sufficient information to perform quantitative data analysis diffraction via in-house software (WBXRD_GUI). Of current interest is the ability to evaluate crystal d-spacing, texture evolution and material phase transitions, all of which will be established from experiments performed at the aforementioned elevated strain-rates.

  2. Simultaneous X-ray diffraction and phase-contrast imaging for investigating material deformation mechanisms during high-rate loading

    SciTech Connect

    Hudspeth, M.; Sun, T.; Parab, N.; Guo, Z.; Fezzaa, K.; Luo, S.; Chen, W.

    2015-01-01

    Using a high-speed camera and an intensified charge-coupled device (ICCD), a simultaneous X-ray imaging and diffraction technique has been developed for studying dynamic material behaviors during high-rate tensile loading. A Kolsky tension bar has been used to pull samples at 1000 s–1and 5000 s–1strain-rates for super-elastic equiatomic NiTi and 1100-O series aluminium, respectively. By altering the ICCD gating time, temporal resolutions of 100 ps and 3.37 µs have been achieved in capturing the diffraction patterns of interest, thus equating to single-pulse and 22-pulse X-ray exposure. Furthermore, the sample through-thickness deformation process has been simultaneously imagedviaphase-contrast imaging. It is also shown that adequate signal-to-noise ratios are achieved for the detected white-beam diffraction patterns, thereby allowing sufficient information to perform quantitative data analysis diffractionviain-house software (WBXRD_GUI). Finally, of current interest is the ability to evaluate crystald-spacing, texture evolution and material phase transitions, all of which will be established from experiments performed at the aforementioned elevated strain-rates.

  3. Simultaneous X-ray diffraction and phase-contrast imaging for investigating material deformation mechanisms during high-rate loading

    DOE PAGES

    Hudspeth, M.; Sun, T.; Parab, N.; ...

    2015-01-01

    Using a high-speed camera and an intensified charge-coupled device (ICCD), a simultaneous X-ray imaging and diffraction technique has been developed for studying dynamic material behaviors during high-rate tensile loading. A Kolsky tension bar has been used to pull samples at 1000 s–1and 5000 s–1strain-rates for super-elastic equiatomic NiTi and 1100-O series aluminium, respectively. By altering the ICCD gating time, temporal resolutions of 100 ps and 3.37 µs have been achieved in capturing the diffraction patterns of interest, thus equating to single-pulse and 22-pulse X-ray exposure. Furthermore, the sample through-thickness deformation process has been simultaneously imagedviaphase-contrast imaging. It is also shownmore » that adequate signal-to-noise ratios are achieved for the detected white-beam diffraction patterns, thereby allowing sufficient information to perform quantitative data analysis diffractionviain-house software (WBXRD_GUI). Finally, of current interest is the ability to evaluate crystald-spacing, texture evolution and material phase transitions, all of which will be established from experiments performed at the aforementioned elevated strain-rates.« less

  4. High-resolution spatiotemporal strain mapping reveals non-uniform deformation in micropatterned elastomers

    NASA Astrophysics Data System (ADS)

    Aksoy, B.; Rehman, A.; Bayraktar, H.; Alaca, B. E.

    2017-04-01

    Micropatterns are generated on a vast selection of polymeric substrates for various applications ranging from stretchable electronics to cellular mechanobiological systems. When these patterned substrates are exposed to external loading, strain field is primarily affected by the presence of microfabricated structures and similarly by fabrication-related defects. The capturing of such nonhomogeneous strain fields is of utmost importance in cases where study of the mechanical behavior with a high spatial resolution is necessary. Image-based non-contact strain measurement techniques are favorable and have recently been extended to scanning tunneling microscope and scanning electron microscope images for the characterization of mechanical properties of metallic materials, e.g. steel and aluminum, at the microscale. A similar real-time analysis of strain heterogeneity in elastomers is yet to be achieved during the entire loading sequence. The available measurement methods for polymeric materials mostly depend on cross-head displacement or precalibrated strain values. Thus, they suffer either from the lack of any real-time analysis, spatiotemporal distribution or high resolution in addition to a combination of these factors. In this work, these challenges are addressed by integrating a tensile stretcher with an inverted optical microscope and developing a subpixel particle tracking algorithm. As a proof of concept, the patterns with a critical dimension of 200 µm are generated on polydimethylsiloxane substrates and strain distribution in the vicinity of the patterns is captured with a high spatiotemporal resolution. In the field of strain measurement, there is always a tradeoff between minimum measurable strain value and spatial resolution. Current noncontact techniques on elastomers can deliver a strain resolution of 0.001% over a minimum length of 5 cm. More importantly, inhomogeneities within this quite large region cannot be captured. The proposed technique can

  5. A high-resolution computational model of the deforming human heart.

    PubMed

    Gurev, Viatcheslav; Pathmanathan, Pras; Fattebert, Jean-Luc; Wen, Hui-Fang; Magerlein, John; Gray, Richard A; Richards, David F; Rice, J Jeremy

    2015-08-01

    Modeling of the heart ventricles is one of the most challenging tasks in soft tissue mechanics because cardiac tissue is a strongly anisotropic incompressible material with an active component of stress. In most current approaches with active force, the number of degrees of freedom (DOF) is limited by the direct method of solution of linear systems of equations. We develop a new approach for high-resolution heart models with large numbers of DOF by: (1) developing a hex-dominant finite element mixed formulation and (2) developing a Krylov subspace iterative method that is able to solve the system of linearized equations for saddle-point problems with active stress. In our approach, passive cardiac tissue is modeled as a hyperelastic, incompressible material with orthotropic properties, and mixed pressure-displacement finite elements are used to enforce incompressibility. Active stress is generated by a model with force dependence on length and velocity of muscle shortening. The ventricles are coupled to a lumped circulatory model. For efficient solution of linear systems, we use Flexible GMRES with a nonlinear preconditioner based on block matrix decomposition involving the Schur complement. Three methods for approximating the inverse of the Schur complement are evaluated: inverse of the pressure mass matrix; least squares commutators; and sparse approximate inverse. The sub-matrix corresponding to the displacement variables is preconditioned by a V-cycle of hybrid geometric-algebraic multigrid followed by correction with several iterations of GMRES preconditioned by sparse approximate inverse. The overall solver is demonstrated on a high-resolution two ventricle mesh based on a human anatomy with roughly 130 K elements and 1.7 M displacement DOF. Effectiveness of the numerical method for active contraction is shown. To the best of our knowledge, this solver is the first to efficiently model ventricular contraction using an iterative linear solver for the mesh

  6. Role of Excited States In High-order Harmonic Generation.

    PubMed

    Beaulieu, S; Camp, S; Descamps, D; Comby, A; Wanie, V; Petit, S; Légaré, F; Schafer, K J; Gaarde, M B; Catoire, F; Mairesse, Y

    2016-11-11

    We investigate the role of excited states in high-order harmonic generation by studying the spectral, spatial, and temporal characteristics of the radiation produced near the ionization threshold of argon by few-cycle laser pulses. We show that the population of excited states can lead either to direct extreme ultraviolet emission through free induction decay or to the generation of high-order harmonics through ionization from these states and recombination to the ground state. By using the attosecond lighthouse technique, we demonstrate that the high-harmonic emission from excited states is temporally delayed by a few femtoseconds compared to the usual harmonics, leading to a strong nonadiabatic spectral redshift.

  7. Role of Excited States In High-order Harmonic Generation

    NASA Astrophysics Data System (ADS)

    Beaulieu, S.; Camp, S.; Descamps, D.; Comby, A.; Wanie, V.; Petit, S.; Légaré, F.; Schafer, K. J.; Gaarde, M. B.; Catoire, F.; Mairesse, Y.

    2016-11-01

    We investigate the role of excited states in high-order harmonic generation by studying the spectral, spatial, and temporal characteristics of the radiation produced near the ionization threshold of argon by few-cycle laser pulses. We show that the population of excited states can lead either to direct extreme ultraviolet emission through free induction decay or to the generation of high-order harmonics through ionization from these states and recombination to the ground state. By using the attosecond lighthouse technique, we demonstrate that the high-harmonic emission from excited states is temporally delayed by a few femtoseconds compared to the usual harmonics, leading to a strong nonadiabatic spectral redshift.

  8. Global feedforward and glocal feedback control of large deformable mirrors

    NASA Astrophysics Data System (ADS)

    Ruppel, Thomas; Sawodny, Oliver

    2011-09-01

    With an increasing demand for high spatial resolution and fast temporal response of AO components for ELTs, the need for actively controlled, electronically damped deformable mirrors is evident. With typically more than 1000 actuators and collocated sensors, the evolving multi-input multi-output control task for shaping the deformable mirror requires sophisticated control concepts. Although global position control of the mirror would be the most promising solution, the computational complexity for high order spatial control of the deformable element typically exceeds available computing power. Due to this reason, existing deformable membrane mirrors for large telescopes incorporate local feedback instead of global feedback control and neglect some of the global dynamics of the deformable mirror. As a side effect, coupling of the separately controlled actuators through the deformable membrane can lead to instability of the individually stable loops and draws the need for carefully designing the control parameters of the local feedback loops. In this presentation, the computational demands for global position control of deformable mirrors are revisited and a less demanding model-based modal control concept for large deformable membrane mirrors with distributed force actuators and collocated position sensors is presented. Both global feedforward and glocal feedback control is employed in a two-degree-of-freedom control structure allowing for separately designing tracking performance and disturbance rejection. In order to implement state feedback control, non-measureable state information is reconstructed by using model-based distributed state observers. By taking into account the circular symmetry of the deformable mirror geometry, the computational complexity of the algorithms is discussed and model reduction techniques with quasi-static state approximation are presented. As an example, the geometric layout of required sensor / actuator wiring and computational

  9. Recrystallization of austenite after deformation at high temperatures and strain rates—Analysis and modeling

    NASA Astrophysics Data System (ADS)

    Laasraoui, A.; Jonas, J. J.

    1991-01-01

    Double-hit compression tests were performed on low-carbon steels containing various combinations of niobium, boron, and copper over a wide range of temperatures and strain rates pertinent to hot rolling. The kinetics of static recrystallization are characterized in terms of the mean flow stresses, which lead to more accurate results than alternative methods. The fractional softening defined by the mean flow stress method was first corrected for adiabatic heating using a simple procedure. Appropriate expressions are given for the recrystallization kinetics as a function of predeformation, temperature, and strain rate. Particular attention is paid to the effect of preloading strain rate on recrystallization kinetics. It is shown that there is a one order of magnitude increase in softening rate when the strain rate is increased by two orders of magnitude. Thus, Simple extrapolations of laboratory data determined at conventional strain rates to high-speed mill conditions are likely to be inaccurate.

  10. Stretchable Thin-Film Electrodes for Flexible Electronics with High Deformability and Stretchability.

    PubMed

    Cheng, Tao; Zhang, Yizhou; Lai, Wen-Yong; Huang, Wei

    2015-06-10

    Flexible and stretchable electronics represent today's cutting-edge electronic technologies. As the most-fundamental component of electronics, the thin-film electrode remains the research frontier due to its key role in the successful development of flexible and stretchable electronic devices. Stretchability, however, is generally more challenging to achieve than flexibility. Stretchable electronic devices demand, above all else, that the thin-film electrodes have the capacity to absorb a large level of strain (>1%) without obvious changes in their electrical performance. This article reviews the progress in strategies for obtaining highly stretchable thin-film electrodes. Applications of stretchable thin-film electrodes fabricated via these strategies are described. Some perspectives and challenges in this field are also put forward.

  11. High energy physics in the United States

    SciTech Connect

    Month, M.

    1985-10-16

    The US program in high energy physics from 1985 to 1995 is reviewed. The program depends primarily upon work at the national accelerator centers, but includes a modest but diversified nonaccelerator program. Involvement of universities is described. International cooperation in high energy physics is discussed, including the European, Japanese, USSR, and the People's Republic of China's programs. Finally, new facilities needed by the US high energy physics program are discussed, with particular emphasis given to a Superconducting Super Collider for achieving ever higher energies in the 20 TeV range. (LEW)

  12. All-optical highly sensitive broadband ultrasound sensor without any deformable parts for photoacoustic imaging

    NASA Astrophysics Data System (ADS)

    Rohringer, Wolfgang; Preißer, Stefan; Liu, Mengyang; Zotter, Stefan; Chen, Zhe; Hermann, Boris; Sattmann, Harald; Fischer, Balthasar; Drexler, Wolfgang

    2016-03-01

    We present a novel akinetic optical ultrasound sensor, consisting of a rigid, fiber-coupled Fabry-Ṕerot interferometer (FPI) with a central opening. The sensing principle relies exclusively on the detection of pressure-induced changes of the refractive index in the liquid located between the cavity mirrors. This enables resonance-free, inherently linear signal detection over a large bandwidth. We demonstrate that the sensor allows to realize exceedingly low noise equivalent pressure (NEP) values of 2 Pa over a 20 MHz measurement bandwidth, while maintaining a large full field of view of 2,7mm × 1,3mm as well as a flat frequency response. Imaging tests on phantoms and biological tissue show the suitability of the XARION-sensor for optical resolution photoacoustic microscopy (OR-PAM) applications. Transparent in axial direction, the sensor facilitates the implementation of highly sensitive fast-scanning reflection-mode OR-PAM setups, as well as easy integration with other imaging modalities such as confocal microscopy or OCT.

  13. Analysis of high temperature deformation mechanism in ODS EUROFER97 alloy

    NASA Astrophysics Data System (ADS)

    Ramar, A.; Spätig, P.; Schäublin, R.

    2008-12-01

    Oxide dispersion in tempered martensitic EUROFER97 steel is an efficient approach to improve its strength. The oxide dispersion strengthened (ODS) EUROFER97 steel shows a good strength up to 600 °C, but degrades rapidly beyond that temperature. To understand the origin in the microstructure of this drop in strength in situ heating experiment in TEM was performed from room temperature to 1000 °C. Upon heating neither microstructure changes nor dislocation movement are observed up to 600 °C. Movement of dislocations are observed above 680 °C. Phase transformation to austenite starts at 840 °C. Yttria particles remain stable up to 1000 °C. Changes in mechanical properties thus do not relate to changes in yttria dispersion. It is attempted to relate these observations to the thermal activation parameters measured by the technique of conventional strain rate experiment, which allow to identify at a mesoscopic scale the microstructural mechanisms responsible for the degradation of ODS steel at high temperatures.

  14. Episodic metamorphism and deformation in low-pressure, high-temperature terranes

    NASA Astrophysics Data System (ADS)

    Stüwe, Kurt; Sandiford, Michael; Powell, Roger

    1993-09-01

    In many cases, low-pressure, high-temperature metamorphism must be the consequence of advective heat transfer, e.g., the ascent of granitic magma. Whereas such heating mechanisms are necessarily short-lived, the lifetime of the underlying orogenic processes is likely to be much longer, and it is conceivable that, during the evolution of an orogen, repeated transient heating at shallow crustal levels is caused by episodes of segregation and upward passage of melts generated at deep crustal levels. The number and timing of these events would depend on such factors as critical melt segregation volume, Moho temperature, and strain-rate evolution. We investigate some of the controls on this multiple-event superposition using a simple thermomechanical model designed to predict, simultaneously, the strain-rate and the isostatic and thermal evolution of convergent orogenesis, subject to a constant driving force. An appealing aspect of this formulation is that, in contrast to models that have attempted to explain event cyclicity through episodic processes acting on the orogenic boundaries, it accounts for the repeated occurrence of events through processes inherent to the orogenic system itself.

  15. Continuum damage modeling for ductile metals under high strain rate deformation

    NASA Astrophysics Data System (ADS)

    Husson, C.; Ahzi, S.; Daridon, L.; Courtine, T.

    2003-09-01

    The accuracy of the computational investigation on the response of ductile materials under dynamic condition depends on the capability of the constitutive model in accounting for strain rate, temperature and microstructural effects. In this work, we propose a damage evolution law, valid for a wide range of strain rates, based on the theory of continuum damage mechanics (CDM). This model implicitly accounts for the three stages of damage: the nucleation, the growth and the coalescence. This non-linear isotropic CDM model for ductile damage is developed by assuming the existence of a new ductile damage dissipation potential. The proposed damage law is coupled with an evolution law for the flow stress. Like in the mechanical threshold stress (M.T.S.) model, the flow stress is decomposed as the sum of an athermal component and a temperature and strain rate dependent component. Results from our motel are in agreement with the existing experimental results for stress-strain behavior and damage evolution in oxygen-free high-conducting (OFHC) copper under both quasi-static and dynamic loading conditions.

  16. Highly deformed band in [sup 136]Pm and the anomalous dynamical moment of inertia behavior in the [ital A][similar to]135 superdeformed region

    SciTech Connect

    Riley, M.A.; Petters, T.; Shick, J.; Archer, D.E.; Doering, J.; Holcomb, J.W.; Johns, G.D.; Johnson, T.D.; Tekyi-Mensah, O.N.; Tabor, S.L.; Womble, P.C.; Wood, V.A. ); Baktash, C.; Halbert, M.L.; Hensley, D.C.; Lee, I.Y. ); Charity, R.J.; Sarantites, D.G.; Wittmer, L.L. ); Simpson, J. )

    1993-02-01

    A highly deformed rotational band has been observed in the odd-odd nucleus [sup 136]Pm. This band sheds important new light on the anomalous behavior of the dynamical moments of inertia of rotational bands previously observed in the Ce-Nd-Sm [ital A][similar to]135 superdeformed region which has been a theoretical puzzle for several years.

  17. Genesis and implication of soft-sediment deformation structures in high-energy fluvial deposits of the Alaknanda Valley, Garhwal Himalaya, India

    NASA Astrophysics Data System (ADS)

    Rana, Naresh; Sati, Saraswati Prakash; Sundriyal, Yaspal; Juyal, Navin

    2016-10-01

    Valley-fill terraces and fluvio-lacustrine sediment successions were investigated for the nature and type of soft-sediment deformation structures (SSDS) in the Alaknanda Valley of the Garhwal Himalaya. Based on their morphologies, sediment characteristics and comparison with existing data on SSDS, these features are classified into seismic and aseismic categories. The study indicates that, despite the terrain being in the seismically active domain of the Central Himalaya, the majority of the deformation structures seem to have been generated aseismically. We attribute their genesis to uneven loading, slope failure and, most importantly, turbulent flow and sudden loading by flash floods. The study suggests that a cautious approach is needed before assigning a seismic origin to deformation structures in sediments deposited in high-energy fluvial systems.

  18. Nanolaminate deformable mirrors

    DOEpatents

    Papavasiliou, Alexandros P.; Olivier, Scot S.

    2009-04-14

    A deformable mirror formed out of two layers of a nanolaminate foil attached to a stiff substrate is introduced. Deformation is provided by an electrostatic force between two of the layers. The internal stiffness of the structure allows for high-spatial-frequency shapes. The nanolaminate foil of the present invention allows for a high-quality mirror surface. The device achieves high precision in the vertical direction by using foils with accurately controlled thicknesses, but does not require high precision in the lateral dimensions, allowing such mirrors to be fabricated using crude lithography techniques. Such techniques allow structures up to about the meter scale to be fabricated.

  19. Nanolaminate deformable mirrors

    DOEpatents

    Papavasiliou, Alexandros P.; Olivier, Scot S.

    2010-04-06

    A deformable mirror formed out of two layers of a nanolaminate foil attached to a stiff substrate is introduced. Deformation is provided by an electrostatic force between two of the layers. The internal stiffness of the structure allows for high-spatial-frequency shapes. The nanolaminate foil of the present invention allows for a high-quality mirror surface. The device achieves high precision in the vertical direction by using foils with accurately controlled thicknesses, but does not require high precision in the lateral dimensions, allowing such mirrors to be fabricated using crude lithography techniques. Such techniques allow structures up to about the meter scale to be fabricated.

  20. DEFORMATION AND FRACTURE OF POORLY CONSOLIDATED MEDIA - Borehole Failure Mechanisms in High-Porosity Sandstone

    SciTech Connect

    Bezalel c. Haimson

    2005-06-10

    We investigated failure mechanisms around boreholes and the formation of borehole breakouts in high-porosity sandstone, with particular interest to grain-scale micromechanics of failure leading to the hitherto unrecognized fracture-like borehole breakouts and apparent compaction band formation in poorly consolidated granular materials. We also looked at a variety of drilling-related factors that contribute to the type, size and shape of borehole breakouts. The objective was to assess their effect on the ability to establish correlations between breakout geometry and in situ stress magnitudes, as well as on borehole stability prediction, and hydrocarbon/water extraction in general. We identified two classes of medium to high porosity (12-30%) sandstones, arkosic, consisting of 50-70% quartz and 15 to 50% feldspar, and quartz-rich sandstones, in which quartz grain contents varied from 90 to 100%. In arkose sandstones critical far-field stress magnitudes induced compressive failure around boreholes in the form of V-shaped (dog-eared) breakouts, the result of dilatant intra-and trans-granular microcracking subparallel to both the maximum horizontal far-field stress and to the borehole wall. On the other hand, boreholes in quartz-rich sandstones failed by developing fracture-like breakouts. These are long and very narrow (several grain diameters) tabular failure zones perpendicular to the maximum stress. Evidence provided mainly by SEM observations suggests a failure process initiated by localized grain-bond loosening along the least horizontal far-field stress springline, the packing of these grains into a lower porosity compaction band resembling those discovered in Navajo and Aztec sandstones, and the emptying of the loosened grains by the circulating drilling fluid starting from the borehole wall. Although the immediate several grain layers at the breakout tip often contain some cracked or even crushed grains, the failure mechanism enabled by the formation of the

  1. Fabrication of Highly-Densified Hydroxyapatite Ceramic with Boron Oxide Addition and Its Superplastic Deformation

    NASA Astrophysics Data System (ADS)

    Itatani, Kiyoshi; Tsuchiya, Kenta; Sakka, Yoshio; Davies, Ian J.; Koda, Seiichiro

    2011-03-01

    Highly-densified and fine-grained hydroxyapatite (Ca10(PO4)6(OH)2: HAp) ceramics with and without 3.0 mol% B2O3 addition were fabricated by pulse-current pressure firing at 1000°C for 10 min under a pressure of 50 MPa. The tensile elongations of HAp ceramics with and without 3.0 mol% B2O3 addition were examined by changing the strain rate from 0.15 to 2.4 × 10-3 s-1 at the test temperature of 1000°C. The tensile elongation of HAp ceramic with no B2O3 addition showed a maximum (474%) at the strain rate of 0.59 × 10-3 s-1. On the other hand, the tensile elongation of HAp ceramic increased to 583% at the strain rate of 2.4 × 10-3 s-1 due to the addition of 3.0 mol% B2O3. Microscopic observation of fractured surfaces of HAp ceramic with 3.0 mol% B2O3 addition showed that the mean grain size decreased from 5.1 to 1.9 μm with increasing strain rate from 0.15 to 2.4 × 10-3 s-1 and that notable amounts of cavities were created among the grains. The time required to achieve the maximum tensile elongation (~580%) of the HAp ceramic could thus be significantly reduced (approximately 1/16, i.e., 12 h to 45 min), due to increasing the strain rate from 0.15 to 2.4 × 10-3 s-1.

  2. Consolidation state of incoming sediments to the Nankai Trough subduction zone: Implications for sediment deformation and properties

    NASA Astrophysics Data System (ADS)

    Kitajima, Hiroko; Saffer, Demian M.

    2014-07-01

    hydromechanical properties of accreted and underthrust sediments are key parameters controlling the mechanics of earthquakes and the development of fluid pressure in subduction zones. We conducted consolidation tests on sediments from the Philippine Sea Plate (PSP) in the Nankai Trough to understand the consolidation state and hydraulic properties of the incoming sediment section before its incorporation into the subduction zone. We used mudstone and sandstone cores sampled from the Integrated Ocean Drilling Program Nankai Trough Seismogenic Zone Experiment at two reference sites (Site C0011 located on a basement low; and Site C0012 located on a basement high). Our experimental results indicate that most of the mudstone samples are normally consolidated or overconsolidated, with overconsolidation ratios (OCR) ranging from 0.89 to 2.52 at Site C0011 and 0.86 to 3.85 at Site C0012. Higher OCR values at Site C0012, at least at shallow depths, are likely caused by erosional unloading. This implies that Site C0011 may serve as a better geotechnical reference site. We also find that mudstones accreted along the frontal thrust are severely overconsolidated relative to coeval mudstones at Site C0011, which likely reflects enhanced consolidation due to increased horizontal tectonic stress. Sandstones in the incoming section on the PSP exhibit 2-3 orders of magnitude higher in situ permeability than the mudstones, and the siliciclastic sandstone we tested maintains a high permeability at stresses up to at least 70 MPa, suggesting that the sandstones may act as important pathways for drainage or pore pressure translation from depths of several kilometers.

  3. High Prevalence of Cervical Deformity and Instability Requires Surveillance in Loeys-Dietz Syndrome

    PubMed Central

    Fuhrhop, Sara K.; McElroy, Mark J.; Dietz, Harry C.; MacCarrick, Gretchen L.; Sponseller, Paul D.

    2015-01-01

    Background: Loeys-Dietz syndrome is a connective tissue disorder characterized by vascular, craniofacial, and musculoskeletal malformation. Our goal was to report the manifestations, surgical treatment, and complications in the cervical spine in patients with Loeys-Dietz syndrome. Methods: We reviewed the clinical and cervical spine imaging data of eighty patients with Loeys-Dietz syndrome who were seen at our institution from January 2005 through January 2014. Their mean age at presentation was 17.3 years (range, three months to seventy-five years). We tested associations with use of the Fisher exact test (type of TGF-βR [transforming growth factor-beta receptor] mutation and cervical abnormalities) and the Student t test (age at presentation and type of TGF-βR mutation) (significance, p = 0.05). Results: Vertebral anomalies and cervical instability were common; we found no significant association of TGF-βR-type with cervical abnormalities or age at presentation. Twenty-eight patients had atlas defects (anterior and/or posterior arch defects or hypoplasia), fifty-three had axis malformations (elongation, apex-anterior dens angulation, or spondylolysis), and twelve had focal kyphosis. Ten patients had hypoplastic subaxial vertebrae, leading to focal kyphosis (eight) and subaxial instability (nine). Eight patients had atlantoaxial instability. Of the thirteen patients with cervical instability, nine were treated surgically: fusion (eight patients) and halo application (one) (mean age, four years; range, three months to twelve years). Postoperative complications (seven patients) were pseudarthrosis, failure of fixation, junctional kyphosis or instability, and development of occipital-cervical instability. Conclusions: Cervical midline defects (most often C1-C3) are common in Loeys-Dietz syndrome. Patients have a high prevalence of cervical instability, particularly a pattern of instability at C2-C3 associated with C3 vertebral body hypoplasia and C2-C3 focal

  4. Equation of state of insensitive high explosives

    SciTech Connect

    Ree, F H; Van Thiel, M; Viecelli, J A

    1998-08-12

    Detonation of an insensitive high explosive formulated with a fluorine containing binder produces a large amount of condensed carbon and gaseous HF product, which transforms into CF{sub 4} as the pressure is increased. The former (carbon condensation) is characterized by slow energy release, while the latter (HF) has no shockwave data. We have identified that these two items are the key factors, which make reliable prediction of the performance of an insensitive high explosive very difficult. This paper describes physical models to address these issues and apply the models to analyze experimental data of LX-17.

  5. Highly improved perinatal states in Japan.

    PubMed

    Maeda, Kazuo

    2014-08-01

    To report on improved perinatal states in Japan, governmental and United Nations Children's Fund reports were analyzed. Initial maternal mortality, which was 409.8 in 1899, decreased to 4.1 in 2010, with a reduction rate of 409.8/4.1 (102.4) in 111 years: 2.5 in the initial 50 years in home delivery and 39.3 in the later 60 years in hospital births. The difference between 2.5 versus 39.3 was attributed to the medicine and medical care provided in hospital births. The total reduction of neonatal mortality was 77.9/1.1 (70.8), and the rate in the initial 50 versus later 60 years was 2.8/25. Also, there was a big difference after introduction of extensive neonatal care. Virtual perinatal mortality after 22 weeks was estimated to be 428 in 1000 births in 1900 (i.e. those infants born at 22-28 weeks were unlikely to survive at that time), while the perinatal mortality was reported to be 22 weeks or more in 1979 (i.e. premature babies born at ≥22 weeks survived in 1979 because of the improved neonatal care). Actually, 60% of premature infants of 400-500 g survived in the neonatal intensive care unit. In a recent report, 36% of infants born at 22 weeks survived to 3 years. Although there were neurodevelopmental impairments, outcomes were improved. In conclusion, perinatal states have remarkably improved in Japan.

  6. State Department Report: Wilde Lake High School.

    ERIC Educational Resources Information Center

    Wilde Lake High School, Columbia, MD.

    The report describes general education courses offered at Wilde Lake High School--a school that maintains a flexible environment conducive to learning and hopefully fosters individual development and growth. The aim of the school is to create an environment that helps students: adjust and cope with their environment outside the school; develop…

  7. Dislocations and deformation microstructure in a B2-ordered Al28Co20Cr11Fe15Ni26 high-entropy alloy.

    PubMed

    Feuerbacher, Michael

    2016-07-19

    High-entropy alloys are multicomponent metallic materials currently attracting high research interest. They display a unique combination of chemical disorder and crystalline long-range order, and due to their attractive properties are promising candidates for technological application. Many high-entropy alloys possess surprisingly high strength, occasionally in combination with high ductility and low density. The mechanisms effecting these attractive mechanical properties are not understood. This study addresses the deformation mechanism of a Al28Co20Cr11Fe15Ni26 high-entropy alloy, which is a two-phase material, consisting of a B2-ordered matrix and disordered body-centred inclusions. We quantitatively analyse the microstructure and dislocations in deformed samples by transmission-electron-microscopic methods including weak-beam imaging and convergent-beam electron diffraction. We find that the deformation process in the B2 phase is dominated by heterogeneous slip of screw dislocations gliding on planes. The dislocations are perfect superdislocations of the B2 lattice and show no dissociation. This indicates that the antiphase-boundary energy in the structure is very high, inhibiting spread of the dislocation core. Along with the observation of a widely extending strain field associated to the dislocations, our results provide a possible explanation for the high strength of this high-entropy alloy as a direct consequence of its dislocation structure.

  8. Dislocations and deformation microstructure in a B2-ordered Al28Co20Cr11Fe15Ni26 high-entropy alloy

    PubMed Central

    Feuerbacher, Michael

    2016-01-01

    High-entropy alloys are multicomponent metallic materials currently attracting high research interest. They display a unique combination of chemical disorder and crystalline long-range order, and due to their attractive properties are promising candidates for technological application. Many high-entropy alloys possess surprisingly high strength, occasionally in combination with high ductility and low density. The mechanisms effecting these attractive mechanical properties are not understood. This study addresses the deformation mechanism of a Al28Co20Cr11Fe15Ni26 high-entropy alloy, which is a two-phase material, consisting of a B2-ordered matrix and disordered body-centred inclusions. We quantitatively analyse the microstructure and dislocations in deformed samples by transmission-electron-microscopic methods including weak-beam imaging and convergent-beam electron diffraction. We find that the deformation process in the B2 phase is dominated by heterogeneous slip of screw dislocations gliding on planes. The dislocations are perfect superdislocations of the B2 lattice and show no dissociation. This indicates that the antiphase-boundary energy in the structure is very high, inhibiting spread of the dislocation core. Along with the observation of a widely extending strain field associated to the dislocations, our results provide a possible explanation for the high strength of this high-entropy alloy as a direct consequence of its dislocation structure. PMID:27430993

  9. Dislocations and deformation microstructure in a B2-ordered Al28Co20Cr11Fe15Ni26 high-entropy alloy

    NASA Astrophysics Data System (ADS)

    Feuerbacher, Michael

    2016-07-01

    High-entropy alloys are multicomponent metallic materials currently attracting high research interest. They display a unique combination of chemical disorder and crystalline long-range order, and due to their attractive properties are promising candidates for technological application. Many high-entropy alloys possess surprisingly high strength, occasionally in combination with high ductility and low density. The mechanisms effecting these attractive mechanical properties are not understood. This study addresses the deformation mechanism of a Al28Co20Cr11Fe15Ni26 high-entropy alloy, which is a two-phase material, consisting of a B2-ordered matrix and disordered body-centred inclusions. We quantitatively analyse the microstructure and dislocations in deformed samples by transmission-electron-microscopic methods including weak-beam imaging and convergent-beam electron diffraction. We find that the deformation process in the B2 phase is dominated by heterogeneous slip of screw dislocations gliding on planes. The dislocations are perfect superdislocations of the B2 lattice and show no dissociation. This indicates that the antiphase-boundary energy in the structure is very high, inhibiting spread of the dislocation core. Along with the observation of a widely extending strain field associated to the dislocations, our results provide a possible explanation for the high strength of this high-entropy alloy as a direct consequence of its dislocation structure.

  10. High Schools in the United States. Quick Stats Fact Sheet

    ERIC Educational Resources Information Center

    National High School Center, 2009

    2009-01-01

    This fact sheet highlights the statistics of the current status of high schools in the United States. It provides information on the following variables: (1) demography of high school students; (2) students with disabilities; (3) high school student achievement; (4) the schools; (5) school funding; (6) high school graduation rate; (7) high school…

  11. Composition Dependence of Phase Stability, Deformation Mechanisms, and Mechanical Properties of the CoCrFeMnNi High-Entropy Alloy System

    NASA Astrophysics Data System (ADS)

    Tasan, C. C.; Deng, Y.; Pradeep, K. G.; Yao, M. J.; Springer, H.; Raabe, D.

    2014-10-01

    The proposal of configurational entropy maximization to produce massive solid-solution (SS)-strengthened, single-phase high-entropy alloy (HEA) systems has gained much scientific interest. Although most of this interest focuses on the basic role of configurational entropy in SS formability, setting future research directions also requires the overall property benefits of massive SS strengthening to be carefully investigated. To this end, taking the most promising CoCrFeMnNi HEA system as the starting point, we investigate SS formability, deformation mechanisms, and the achievable mechanical property ranges of different compositions and microstructural states. A comparative assessment of the results with respect to room temperature behavior of binary Fe-Mn alloys reveals only limited benefits of massive SS formation. Nevertheless, the results also clarify that the compositional requirements in this alloy system to stabilize the face-centered cubic (fcc) SS are sufficiently relaxed to allow considering nonequiatomic compositions and exploring improved strength-ductility combinations at reduced alloying costs.

  12. Assessment of the metrological performance of an in situ storage image sensor ultra-high speed camera for full-field deformation measurements

    NASA Astrophysics Data System (ADS)

    Rossi, Marco; Pierron, Fabrice; Forquin, Pascal

    2014-02-01

    Ultra-high speed (UHS) cameras allow us to acquire images typically up to about 1 million frames s-1 for a full spatial resolution of the order of 1 Mpixel. Different technologies are available nowadays to achieve these performances, an interesting one is the so-called in situ storage image sensor architecture where the image storage is incorporated into the sensor chip. Such an architecture is all solid state and does not contain movable devices as occurs, for instance, in the rotating mirror UHS cameras. One of the disadvantages of this system is the low fill factor (around 76% in the vertical direction and 14% in the horizontal direction) since most of the space in the sensor is occupied by memory. This peculiarity introduces a series of systematic errors when the camera is used to perform full-field strain measurements. The aim of this paper is to develop an experimental procedure to thoroughly characterize the performance of such kinds of cameras in full-field deformation measurement and identify the best operative conditions which minimize the measurement errors. A series of tests was performed on a Shimadzu HPV-1 UHS camera first using uniform scenes and then grids under rigid movements. The grid method was used as full-field measurement optical technique here. From these tests, it has been possible to appropriately identify the camera behaviour and utilize this information to improve actual measurements.

  13. On the use of a split Hopkinson pressure bar in structural geology: High strain rate deformation of Seeberger sandstone and Carrara marble under uniaxial compression

    NASA Astrophysics Data System (ADS)

    Zwiessler, Ruprecht; Kenkmann, Thomas; Poelchau, Michael H.; Nau, Siegfried; Hess, Sebastian

    2017-04-01

    There is increasing evidence that seismogenic fractures can propagate faster than the shear wave velocity of the surrounding rocks. Strain rates within the tip region of such super-shear earthquake ruptures can reach deformation conditions similar to impact processes, resulting in rock pulverization. The physical response of brittle rocks at high strain rates changes dramatically with respect to quasi-static conditions. Rocks become stiffer and their strength increases. A measure for the dynamic behavior of a rock and its strain dependency is the dynamic increase factor (DIF) which is the ratio of the dynamic compressive strength to the quasi-static uniaxial compressive strength. To investigate deformation in the high strain rate regime experimentally, we introduce the split Hopkinson pressure bar technology to the structural geology community, a method that is frequently used by rock and impact engineers. We measure the stress-strain response of homogeneous, fine-grained Seeberger sandstone and Carrara marble in uniaxial compression at strain rates ranging from 10+1 to 10+2 s-1 with respect to tangent modulus and dynamic uniaxial compressive strength. We present full stress-strain response curves of Seeberger sandstone and Carrara marble at high strain rates and an evaluation method to determine representative rates of deformation. Results indicate a rate-dependent elastic behavior of Carrara marble where an average increase of ∼18% could be observed at high strain rates of about 100 s-1. DIF reaches a factor of 2.2-2.4. Seeberger sandstone does not have a rate-dependent linear stress-strain response at high strain rates. Its DIF was found to be about 1.6-1.7 at rates of 100 s-1. The onset of dynamic behavior is accompanied with changes in the fracture pattern from single to multiple fractures to pervasive pulverization for increasing rates of deformation. Seismogenic shear zones and their associated fragment-size spectra should be carefully revisited in the

  14. A numerical and experimental study of temperature effects on deformation behavior of carbon steels at high strain rates

    NASA Astrophysics Data System (ADS)

    Pouya, M.; Winter, S.; Fritsch, S.; F-X Wagner, M.

    2017-03-01

    Both in research and in the light of industrial applications, there is a growing interest in methods to characterize the mechanical behavior of materials at high strain rates. This is particularly true for steels (the most important structural materials), where often the strain rate-dependent material behavior also needs to be characterized in a wide temperature range. In this study, we use the Finite Element Method (FEM), first, to model the compressive deformation behavior of carbon steels under quasi-static loading conditions. The results are then compared to experimental data (for a simple C75 steel) at room temperature, and up to testing temperatures of 1000 °C. Second, an explicit FEM model that captures wave propagation phenomena during dynamic loading is developed to closely reflect the complex loading conditions in a Split-Hopkinson Pressure Bar (SHPB) – an experimental setup that allows loading of compression samples with strain rates up to 104 s-1 The dynamic simulations provide a useful basis for an accurate analysis of dynamically measured experimental data, which considers reflected elastic waves. By combining numerical and experimental investigations, we derive material parameters that capture the strain rate- and temperature-dependent behavior of the C75 steel from room temperature to 1000 °C, and from quasi-static to dynamic loading.

  15. Effects of Deformation-Induced Constraint on High-Cycle Fatigue in Ti Alloys with a Duplex Microstructure

    NASA Astrophysics Data System (ADS)

    Chan, K. S.; Lee, Y.-D.

    2008-07-01

    The effects of the deformation behaviors of individual phases in Ti alloys with a duplex microstructure containing a mixture of primary α grains and lamellar α + β colonies have been analyzed by applying the finite-element method (FEM) to the relevant microstructure. The softer primary α grains and the harder lamellar α + β colonies are treated as distinct microstructural units with different constitutive properties. The FEM results indicate that the softer (primary α) phase, which reaches yielding first, tends to concentrate both the plastic strain and the hydrostatic stress, whose magnitudes depend on the volume fraction of the primary α grains and the load levels. The insight from the FEM analyses has been used to modify the linear relation between alternating stress and mean stress in a Haigh or modified Goodman diagram by incorporating a microstructure-induced hydrostatic stress term, leading to a set of bilinear relations for high-cycle fatigue (HCF) failures of Ti alloys with a duplex microstructure. The applicability of the micromechanical approach to treating the mean stress effects in HCF failure of Ti-6Al-4V with various duplex microstructures is elucidated by comparison against experimental data in the literature.

  16. Microstructural characteristics of adiabatic shear localization in a metastable beta titanium alloy deformed at high strain rate and elevated temperatures

    SciTech Connect

    Zhan, Hongyi; Zeng, Weidong; Wang, Gui; Kent, Damon; Dargusch, Matthew

    2015-04-15

    The microstructural evolution and grain refinement within adiabatic shear bands in the Ti6554 alloy deformed at high strain rates and elevated temperatures have been characterized using transmission electron microscopy. No stress drops were observed in the corresponding stress–strain curve, indicating that the initiation of adiabatic shear bands does not lead to the loss of load capacity for the Ti6554 alloy. The outer region of the shear bands mainly consists of cell structures bounded by dislocation clusters. Equiaxed subgrains in the core area of the shear band can be evolved from the subdivision of cell structures or reconstruction and transverse segmentation of dislocation clusters. It is proposed that dislocation activity dominates the grain refinement process. The rotational recrystallization mechanism may operate as the kinetic requirements for it are fulfilled. The coexistence of different substructures across the shear bands implies that the microstructural evolution inside the shear bands is not homogeneous and different grain refinement mechanisms may operate simultaneously to refine the structure. - Graphical abstract: Display Omitted - Highlights: • The microstructure within the adiabatic shear band was characterized by TEM. • No stress drops were observed in the corresponding stress–strain curve. • Dislocation activity dominated the grain refinement process. • The kinetic requirements for rotational recrystallization mechanism were fulfilled. • Different grain refinement mechanisms operated simultaneously to refine the structure.

  17. Structural Stability and Deformation of Solvated Sm@C2(45)-C90 under High Pressure

    PubMed Central

    Cui, Jinxing; Yao, Mingguang; Yang, Hua; Liu, Ziyang; Liu, Shijie; Du, Mingrun; Li, Quanjun; Liu, Ran; Cui, Tian; Liu, Bingbing

    2016-01-01

    Solvated fullerenes recently have been shown to exhibit novel compression behaviors compared with the pristine fullerenes. However, less attention has been focused on the large cage endohedral metallofullerenes. Here, we have firstly synthesized solvated Sm@C90 microrods by a solution drop-drying method, and then studied the transformations under high pressure. The pressure-induced structural evolutions of Sm@C90 molecules both undergo deformation and collapse. The band gaps of both samples decrease with increasing pressure. The trapped Sm atom plays a role in restraining the compression of the adjacent bonds. The solvent plays a role in protecting Sm@C90 against collapse in the region of 12–20 GPa, decreasing and postponing the change of band gap. Above 30 GPa, the carbon cages collapse. Released from 45 GPa, the compressed solvated Sm@C90 forms a new ordered amorphous carbon cluster (OACC) structure with metal atoms trapped in the units of amorphous carbon clusters, which is different from the OACC structure formed by compressing solvated C60 and C70. This discovery opens the door for the creation of new carbon materials with desirable structural and physical properties when suitable starting materials are selected. PMID:27503144

  18. Structural Stability and Deformation of Solvated Sm@C2(45)-C90 under High Pressure.

    PubMed

    Cui, Jinxing; Yao, Mingguang; Yang, Hua; Liu, Ziyang; Liu, Shijie; Du, Mingrun; Li, Quanjun; Liu, Ran; Cui, Tian; Liu, Bingbing

    2016-08-09

    Solvated fullerenes recently have been shown to exhibit novel compression behaviors compared with the pristine fullerenes. However, less attention has been focused on the large cage endohedral metallofullerenes. Here, we have firstly synthesized solvated Sm@C90 microrods by a solution drop-drying method, and then studied the transformations under high pressure. The pressure-induced structural evolutions of Sm@C90 molecules both undergo deformation and collapse. The band gaps of both samples decrease with increasing pressure. The trapped Sm atom plays a role in restraining the compression of the adjacent bonds. The solvent plays a role in protecting Sm@C90 against collapse in the region of 12-20 GPa, decreasing and postponing the change of band gap. Above 30 GPa, the carbon cages collapse. Released from 45 GPa, the compressed solvated Sm@C90 forms a new ordered amorphous carbon cluster (OACC) structure with metal atoms trapped in the units of amorphous carbon clusters, which is different from the OACC structure formed by compressing solvated C60 and C70. This discovery opens the door for the creation of new carbon materials with desirable structural and physical properties when suitable starting materials are selected.

  19. Mapping of dose distribution from IMRT onto MRI-guided high dose rate brachytherapy using deformable image registration for cervical cancer treatments: preliminary study with commercially available software

    PubMed Central

    Huq, M. Saiful; Houser, Chris; Beriwal, Sushil; Michalski, Dariusz

    2014-01-01

    Purpose For patients undergoing external beam radiation therapy (EBRT) and brachytherapy, recommendations for target doses and constraints are based on calculation of the equivalent dose in 2 Gy fractions (EQD2) from each phase. At present, the EBRT dose distribution is assumed to be uniform throughout the pelvis. We performed a preliminary study to determine whether deformable dose distribution mapping from the EBRT onto magnetic resonance (MR) images for the brachytherapy would yield differences in doses for organs at risk (OARs) and high-risk clinical target volume (HR-CTV). Material and methods Nine cervical cancer patients were treated to a total dose of 45 Gy in 25 fractions using intensity-modulated radiation therapy (IMRT), followed by MRI-based 3D high dose rate (HDR) brachytherapy. Retrospectively, the IMRT planning CT images were fused with the MR image for each fraction of brachytherapy using deformable image registration. The deformed IMRT dose onto MR images were converted to EQD2 and compared to the uniform dose assumption. Results For all patients, the EQD2 from the EBRT phase was significantly higher with deformable registration than with the conventional uniform dose distribution assumption. The mean EQD2 ± SD for HR-CTV D90 was 45.7 ± 0.7 Gy vs. 44.3 Gy for deformable vs. uniform dose distribution, respectively (p < 0.001). The dose to 2 cc of the bladder, rectum, and sigmoid was 46.4 ± 1.2 Gy, 46.2 ± 1.0 Gy, and 48.0 ± 2.5 Gy, respectively with deformable dose distribution, and was significantly higher than with uniform dose distribution (43.2 Gy for all OAR, p < 0.001). Conclusions This study reveals that deformed EBRT dose distribution to HR-CTV and OARs in MR images for brachytherapy is technically feasible, and achieves differences compared to a uniform dose distribution. Therefore, the assumption that EBRT contributes the same dose value may need to be carefully investigated further based on deformable image registration. PMID:25097559

  20. Deformation and melt transport in a highly depleted peridotite massif from the Canadian Cordillera: Implications to seismic anisotropy above subduction zones

    NASA Astrophysics Data System (ADS)

    Tommasi, Andréa; Vauchez, Alain; Godard, Marguerite; Belley, France

    2006-12-01

    Seismic anisotropy in subduction zones results from a combination of various processes. Although it depends primarily on the orientation of olivine in response to flow, the presence of water and melt in the wedge may modify the deformation of olivine. The melt distribution also influences anisotropy. Direct observations of the deformation and melt-rock interactions in a strongly depleted spinel-harzburgite massif from the Cache Creek terrane in the Canadian Cordillera allow evaluating the relative contribution of each process. Structural mapping shows that this massif has recorded high-temperature, low-stress deformation, high degrees of partial melting, and synkinematic melt-rock interaction at shallow depths (< 70 km) in the mantle, probably above an oblique subduction. Deformation, marked by shallow-dipping lineations and steep foliations, controlled melt distribution: reactive dunites and pyroxenite dykes are dominantly parallel to the foliation. Analysis of olivine crystal preferred orientations (CPO) indicates deformation by dislocation creep with dominant [100] glide. Glide planes are however different in harzburgites and dunites, suggesting that higher melt contents may favor glide on (001) relative to (010). Seismic properties, calculated by considering explicitly the large-scale structure of the massif, the olivine and pyroxene CPO, and possible melt distributions, show that the strain-induced olivine CPO results in up to 5% P- and S-wave anisotropy with fast seismic directions parallel to the lineation. Synkinematic melt transport by diffuse porous flow leading to melt pockets or dykes aligned in the foliation may significantly enhance this anisotropy, in particular for S-waves. In contrast, focused melt flow is not recorded by seismic anisotropy, unless associated with very high instantaneous melt fractions. Orientation of pyroxenite dykes suggests that the present orientation of the structures is representative of the pre-obduction situation, implying