Octupole Deformed Nuclei in the Actinide Region
Thorsteinsen, T; Rubio barroso, B; Simpson, J; Gulda, K; Sanchez-vega, M; Cocks, J; Nybo, K; Garcia borge, M; Aas, A; Fogelberg, B; Honsi, J; Smith, G; Naumann, R; Grant, I
2002-01-01
The aim of the present study is to investigate the limits of the "island" of octupole deformation in the mass region A=225. It is of particular importance to demonstrate experimentally the sudden disappearance of the stable octupole deformation in the presence of a well developed quadrupole field. \\\\ \\\\In order to establish the upper border line the $\\beta$ -decay chains of $^{227}$Rn $\\rightarrow ^{227}$Fr $\\rightarrow ^{227}$Ra and $^{231}$Fr $\\rightarrow ^{231}$Ra $\\rightarrow ^{231}$Ac were studied at PSB-ISOLDE using advanced fast timing and $\\gamma$-ray spectroscopy techniques. The lifetimes of the excited states have been measured in the picosecond range using the time-delayed $\\beta\\gamma\\gamma$(t) method.
Nuclear dynamical octupole deformation in heavy-ion reactions
Tang, Cheng; Jin, Xin; Wang, Nan; Zhao, En-Guang
2015-10-01
Within the quantum molecular dynamics (QMD) model, the dynamical octupole deformation is studied as a function of the central distance between the projectile and target in the approaching process of heavy-ion fusion reactions. The dependence of the maximum dynamical octupole deformations on the incident energies is also investigated. The dynamical octupole deformations can be observed during the approaching process, and the maximum dynamical octupole deformations become more significant with decreasing incident energies. The distributions of the proton and neutron centers in the projectile and target are also investigated, respectively. In the approaching process of heavy-ion fusion reactions, the separation between proton centers for two nuclei is larger than that between neutron centers because of the strong Coulomb potential.
Deformed Hartree-Fock model of parity mixing and octupole moments in neutron rich barium nuclei
International Nuclear Information System (INIS)
A deformed Hartree-Fock calculation with parity mixing reveals considerable octupole deformation for neutron rich barium nuclei. The energy surfaces for 142-148Ba as a function of octupole deformation are calculated and show a single humped shape with the minimum for positive octupole deformation slightly lower in energy. Parity mixing and octupole deformation show a typical shell effect and are negligible for 146Ce and 148Ce. (author)
Search for octupole deformation in neutron rich Xe isotopes
International Nuclear Information System (INIS)
A search for octupole deformation in neutron rich Xe isotopes has been conducted through gamma-ray spectroscopy of primary fragments produced in the spontaneous fission of 248Cm. The spectrometer consisted of the Eurogam array and a set of 5 LEPS detectors. Level schemes were constructed for Xe isotopes with masses ranging from 138 to 144. Except for 139Xe, none of them exhibit an alternating parity quasimolecular band, ? feature usually encountered in octupole deformed nuclei. Substantial evidence for reflection asymmetric shape in the intrinsic system of the nucleus exists for the light actinide nuclei
The Structure of Heavy Octupole and Superheavy Quadrupole Deformed Nuclei
International Nuclear Information System (INIS)
We report here experimental attempts to determine the sign of the electric dipole moment (relative to the electric octupole moment) in the octupole deformed nucleus 226Ra. Sensitivity to this quantity is observed in the measured yields of ?-ray transitions following very low energy Coulomb excitation. Recent progress is also reported in the development of new spectroscopic techniques that promise to elucidate the structure of deformed superheavy nuclei in the region of 254No. The 4+?2+ transition in 254No as well as higher spin transitions, has been identified using recoil-tagged conversion electron spectroscopy. (author)
Possible ground-state octupole deformation in 229Pa
International Nuclear Information System (INIS)
Evidence is presented for the occurrence of a (5/2)+- parity doublet as the ground state of 229Pa, in agreement with a previous theoretical prediction. The doublet splitting energy is measured to be 0.22 +- 0.05 keV. The relation of this doublet to ground-state octupole deformation is discussed. .ID LV2109 .PG 1762 1764
Studies of Stable Octupole Deformations in the Radium Region
2002-01-01
The purpose of the present project is to locate and identify states in the atomic nuclei possessing stable pearshaped octupole deformation. Such states, formally related to the structures known in molecular physics, manifest themselves as families of parity doublets in odd nuclei.\\\\ \\\\ The best possibilities for observing stable octupole deformations are offered in the Ra-region. Both theoretical calculations and experimental indications support such expectations. Such indications are the non-observation of two-phonon octupole vibrational states in the ISOLDE studies of the even-even radium nuclei, and the reversed sign of the decoupling factor of the ground state band in |2|2|5Ra observed in the single-neutron transfer reactions. In order to establish the predicted strong E1 and E3-transitions between the parity doublets in odd nuclei with stable octupole deformations it is proposed to study conversion electrons in odd-mass francium radium and radon isotopes following the @b-decay of francium and astatine. \\...
Nuclear fusion as a probe for octupole deformation in 224Ra
Kumar, Raj; Lay, J. A.; Vitturi, A.
2015-11-01
Background: Nuclear fusion has been shown to be a useful probe to study the different nuclear shapes. However, the possibility of testing octupole deformation of a nucleus with this tool has not been fully explored yet. The presence of a static octupole deformation in nuclei will enhance a possible permanent electric dipole moment, leading to a possible demonstration of parity violation. Purpose: To check whether static octupole deformation and octupole vibration in fusion give different results so that both situations could be experimentally disentangled. Method: Fusion cross sections are computed in the coupled-channel formalism making use of the ingoing-wave boundary conditions (IWBC) for the systems 16O+144Ba and 16O+224Ra . Results: Barrier distributions of the two considered schemes show slightly different patterns. In the case of 144Ba, the difference between them is negligible. For the 224Ra case, perceptible differences are found in correspondence with its larger octupole deformation. However, the possibility of disentangling both schemes is not guaranteed and it will depend on the available experimental accuracy and the strength of the octupole deformation. Conclusions: The measurement of barrier distributions could be a complementary probe to support the presence of octupole deformation.
Octupole deformation for Ba isotopes in a reflection-asymmetric relativistic mean-field approach
International Nuclear Information System (INIS)
The potential energy surfaces of even-even 142-156Ba are investigated in the constrained reflection-asymmetric relativistic mean-field approach with parameter set PK1. It is shown that for the ground states, 142Ba is near spherical, 156Ba well quadrupole-deformed, and in between 144-154Ba octupole deformed. In particular, the nuclei 148,150Ba with N=92, 94 have the largest octupole deformations. By including the octupole degree of freedom, energy gaps N = 88, N = 94 and Z = 56 near Fermi surfaces for the single-particle levels in 148Ba with ?2 ? 0.26 and ?3 ? 0.17 are found. Furthermore, the performance of the octupole deformation driving pairs (?2f7/2, ?1i13/2) and (?2d5/2, ?1h11/2) is demonstrated by analyzing the single-particle levels near Fermi surfaces in 148Ba. (authors)
Definition of the actinide region of static quadrupole-octupole deformation
International Nuclear Information System (INIS)
Ground state spins of odd-A nuclei in the region just beyond 208Pb are compiled. They are compared with the theoretically predicted spins of an axially symmetric, reflection asymmetric nucleus with octupole deformaiton ?3 = 0.08 to determine the region of static quadrupole-octupole deformation. Coexistence of different shapes and the corresponding spectra in the same nucleus are predicted in the transition regions. (orig.)
Stabilization of octupole deformation with angular-momentum increase in the alternating-parity bands
Jolos, R. V.; von Brentano, P.
2015-10-01
Background: Low-lying octupole collective excitations play an important role in describing the structure of nuclei in different regions of the nuclide chart. Ground state alternating-parity rotational bands combining both positive- and negative-parity states are known in several nuclei. The experimental data indicate that octupole deformation becomes stable with increase of the angular momentum. Purpose: We introduce a nondimensional characteristic of the spectra of the ground state alternating-parity bands and apply it to investigation of a stabilization of the octupole deformation with increase of the angular momentum. Method: We analyze the experimental data on the energies of the states belonging to the alternating-parity bands based on the ratio of the interpolated and the experimental energies of the negative-parity states. Interpolated energies are determined by the experimental energies of the neighboring positive-parity states assuming smooth dependence on the angular momentum. Results: The values of the ratio of the interpolated and the experimental energies of the negative-parity states belonging to the ground state alternating-parity bands of 144 ,146Ba and some rare-earth and actinide nuclei are evaluated. Conclusion: It is shown that the angular-momentum dependence of the ratio of the interpolated and the experimental energies of the negative-parity states belonging to the ground state alternating-parity bands of 144 ,146Ba and some rare-earth and actinide nuclei indicates stabilization of the octupole deformation with angular-momentum increase.
Exotic octupole deformation in proton-rich Z=N nuclei
Energy Technology Data Exchange (ETDEWEB)
Takami, Satoshi; Yabana, K. [Niigata Univ. (Japan); Matsuo, M.
1998-03-01
We study static non-axial octupole deformations in proton-rich Z=N nuclei, {sup 64}Ge, {sup 68}Se, {sup 72}Kr, {sup 76}Sr, {sup 80}Zr and {sup 84}Mo, by using the Skyrme Hartree-Fock plus BCS method with no restrictions on the nuclear shape. The calculation predicts that the oblate ground state in {sup 68}Se is extremely soft for the Y{sub 33} triangular deformation, and that in {sup 80}Zr the low-lying local minimum state coexisting with the prolate ground state has the Y{sub 32} tetrahedral deformation. (author)
International Nuclear Information System (INIS)
A method for setting ?f, one of the parameters in the interacting boson approximation-1 (IBA-1) with one f boson, by using the systematic behavior of the centroids of observed E3 strength is proposed and applied to obtaining fits for octupole bands in the deformed rare earth region. The ordering of bands with different K values, B(E3) strengths and B(E1) values are well reproduced. The calculations are in good agreement with the data in nearly all the K=0, 1, and 2 octupole bands examined here. The least satisfactory fits were obtained for the K?=0- bands in 160,162Dy. It is predicted that in 160,162,164Dy, 168Er, and 172Yb the K=3 octupole states based on the ground state and having significant E3 strength are above 6 MeV and are strongly fragmented. These results are quite different from predictions made previously. copyright 1996 The American Physical Society
International Nuclear Information System (INIS)
Strong E1 transitions of greater than 10-3 Weisskopf units occur in many octupole states in the deformed rare earth region. It is shown using the droplet model that the electric dipole moment resulting from the macroscopic behaviour of the octupole phonon cannot by itself account for the observed E1 strengths, and it is observed that this result is consistent with the proposal of Donner and Greiner and of Zilges von Brentano and Richter that admixtures of the giant dipole resonance into the low energy octupole states are responsible for the fast E1 transitions. It is also suggested that calculations similar to those performed by Egido and Robledo for N ? 92 nuclei may be able to reproduce E1 transitions in N = 94-104 nuclei. (orig.)
First Atomic Electric Dipole Moment Limit Derived from an Octupole-Deformed Nucleus
Parker, Richard; Bishof, Michael; Kalita, Mukut; Lemke, Nathan; Dietrich, Matt; Bailey, Kevin; Greene, John; Holt, Roy; Korsch, Wolfgang; Lu, Zheng-Tian; Mueller, Peter; O'Connor, T. P.; Singh, Jaideep
2015-05-01
Ra-225 (half-life = 15 d, nuclear spin = 1/2) is a promising isotope for a measurement of the EDM of a diamagnetic atom. Due to its large nuclear octupole deformation and high atomic mass, the EDM sensitivity of Ra-225 is expected to be 2-3 orders of magnitude larger than that of Hg-199. We demonstrate an efficient multiple-stage apparatus in which radium atoms are first loaded into a MOT, then transferred into a movable optical-dipole trap (ODT) that carries the atoms over 1 m to a magnetically-shielded science chamber, loaded into a standing-wave ODT, polarized, and then allowed to precess in magnetic and electric fields. We will discuss our first measurement of the EDM of Ra-225, as well as plans for future improvements. This work is supported by DOE, Office of Nuclear Physics (DE-AC02-06CH11357).
Study of octupole deformation in n-rich Ba isotopes populated via $\\beta$-decay
We propose to exploit the unique capability of the ISOLDE facility to produce $^{150?151?152}$Cs beams to investigate their radioactive $\\beta$-decay to $^{150?151?152}$Ba. The interest to study this mass region is twofold: from one side these nuclei are expected to show octupole deformations already in their low-lying state, and, on the other hand, gross information on the $\\beta$-decay is highly demanded for nuclear astrophysical model, given the fact that the r-process path lies in the proximity of 1 accessible nuclei. The experiment will be performed with the ISOLDE Decay Station (IDS) setup using the fast tape station of K.U.-Leuven, equipped with 4 Clover Germanium detectors, 4 LaBr$_{3}$(Ce) detectors and 1 LEP HPGe detector. Information on the $\\beta$-decay, such as lifetimes and delayed neutron-emission probabilities, will be extracted, together with the detailed spectroscopy of the daughter nuclei, via $\\gamma$ - $\\gamma$- coincidences and lifetimes measurement of specific states.
Enhanced E1 transition rates and octupole deformation in 225Ac
International Nuclear Information System (INIS)
The levels of 225Ac are reliably assigned by detailed measurements of the radiations associated with the ? decay of 229Pa and the ? decay of 225Ra. Extremely large enhancements of E1 transition rates are found in 225Ac. The adequacy of a single-particle description of strong octupole correlations is examined
Identification of excited states and evidence for octupole deformation in sup 2 sup 2 sup 6 U
Greenlees, P T
1999-01-01
Excited yrast states in the neutron-deficient nucleus sup 2 sup 2 sup 6 U have been identified in two experiments performed at the Accelerator Laboratory of the University of Jyvaeskylae, Finland. In the first, the technique of recoil-decay tagging was employed using the JUROSPHERE plus RITU device, where the reaction channel of interest is selected through correlation with a characteristic decay. In the second, the RITU device was employed to study the alpha decay of sup 2 sup 3 sup 0 Pu. Through these experiments the level scheme of sup 2 sup 2 sup 6 U was deduced for the first time. Interleaved bands of positive- and negative- parity states suggest the octupole nature of this nucleus, and the behaviour of the difference in aligned angular momentum between the negative- and positive- parity states with rotational frequency is consistent with that expected of a rotating reflection-asymmetric shape. This represents an extension of the known octupole-deformed nuclei to Z = 92. The interleaved bands of alternat...
Identification of Excited States in 226U: Evidence for Octupole Deformation
International Nuclear Information System (INIS)
The level scheme of 226U has been deduced from the results of two experiments carried out at the University of Jyvaskyla, Finland. Both ?- and ?-ray-spectroscopic techniques have been employed. The interleaved states of positive- and negative-parity indicate the octupole nature of this nucleus, and the behavior of the difference in aligned angular momentum between the positive- and negative-parity bands as a function of rotational frequency is consistent with that expected for a rotating reflection-asymmetric shape
Octupole shaps in nuclei, and some rotational consequences thereof
International Nuclear Information System (INIS)
During the last years a large number of experimental papers presenting spectroscopic evidence for collective dipole and octupole deformations have appeared. Many theoretical attempts have been made to explain the observed spectroscopic properties in terms of stable octupole deformations. The coupling by the octupole potential, being proportional to Y30, is strongest for those subshells for which ?1 = 3. Therefore the tendency towards octupole deformation occurs just beyond closed shells where the high-j intruder subshells (N,1,j) lie very close to the normal parity subshells (N-1,1-3,j-3), i.e. for the particle numbers 34 (g/sub 9/2/-p/sub 3/2/), 56 (h/sub 11/2/-d/sub 5/2/). 9C (i/sub 13/2/-f/sub 7/2/) and 134 (j/sub 15/2/-g/sub 9/2/). Empirically, it is specifically for the particle numbers listed above that negative parity states are observed at relatively low energies in doubly even nuclei. From the different combinations of octupole-driving particle numbers four regions of likely candidates for octupole deformed equilibrium shapes emerge, namely the neutron-deficient nuclei with Z approx. = 90, N approx. = 134 (light actinides) and Z approx. = 34, N approx. = 34 (A approx. = 70) and the neutron-rich nuclei with Z approx. = 56, N approx. = 90 (heavy Ba) and Z approx. = 34, N56 (A approx. = 90). In our calculations we searched for octupole unstable nuclei in these four mass regions. The Strutinsky method with the deformed Woods-Saxon potential was employed. The macroscopic part consists of a finite-range liquid drop energy, where both the surface and Coulomb terms contain a diffuseness correction
Test of the transport properties of a helical electrostatic quadrupole and quasi-octupole
International Nuclear Information System (INIS)
A third-generation continuous helical electrostatic quadrupole (HESQ) lens has been built and tested. The new HESQ is 21.5 cm long and has a 3.6 cm diameter aperture. The HESQ has been tested under two separate conditions: with a pulsed 25 keV, 0.5 mA proton beam; and a 25 keV, 10 mA proton beam. The input emittance was fixed using a multi-aperture collimator. A comparison is made between experiment and numerical simulations for a wide variety of operating conditions. A second possible operating mode is the quasi-octupole mode, which offers significantly reduced aberration when compared to the quadrupole mode. The results of preliminary tests in this operating mode will be presented
Octupole collectivity in the Sm isotopes
International Nuclear Information System (INIS)
Microscopic models suggest the occurrence of strong octupole correlations in nuclei with N?88. To examine the signatures of octupole correlations in this region, the spdf interacting boson approximation model is applied to Sm isotopes with N=86-92. The effects of including multiple negative-parity bosons in this basis are compared with more standard one negative-parity boson calculations and are analyzed in terms of signatures for strong octupole correlations. It is found that multiple negative-parity bosons are needed to describe properties at medium spin. Bands with strong octupole correlations (multiple negative-parity bosons) become yrast at medium spin in 148,150Sm. This region shares some similarities with the light actinides, where strong octupole correlations were also found at medium spin
Octupole Vibrations at High Angular Momenta
Nakatsukasa, takashi
1995-01-01
Properties of octupole vibrations in rapidly rotating nuclei are discussed. Microscopic RPA calculations based on the cranked shell model are performed to investigate the interplay between rotation and vibrations. The ability of this model to describe the properties of collective vibrations built on the ground bands in rare-earth and actinide nuclei is demonstrated at high angular momentum. The octupole vibrational states in even-even superdeformed Hg nuclei are also predict...
Simultaneous quadrupole and octupole shape phase transitions in Thorium
Li, Z P; Yao, J M; Vretenar, D; Meng, J
2013-01-01
The evolution of quadrupole and octupole shapes in Th isotopes is studied in a fully microscopic framework based on nuclear Density Functional Theory. The constrained potential energy maps and observables calculated with microscopic collective Hamiltonians, indicate the occurrence of a simultaneous quantum shape phase transition between spherical and quadrupole-deformed prolate shapes, and between non-octupole and octupole-deformed shapes, as functions of the nucleon number. $^{224}$Th is predicted closest to the critical point of the double phase transition. A microscopic mechanism of this phenomenon is discussed in terms of the evolution of single-nucleon orbitals with deformation.
Octupole instability in the heavy barium region
International Nuclear Information System (INIS)
The Woods-Saxon-Bogolyubov cranking calculations confirm previous expectations of octupole deformed mean fields at low and medium spins in Xe-Sm nuclei with neutron numbers around N=86. Recent experimental data support theoretical results. 8 refs., 3 figs. (author)
Evidence for octupole vibration in the superdeformed well of 109Hg
International Nuclear Information System (INIS)
An excited superdeformed (SD) band has been observed in 19OHg which decays to the lowest-energy (yrast) SD band rather than to the less deformed states as observed in most known SD bands in the A?150 and A?190 regions. The band exhibits properties which are in good agreement with predictions of collective octupole vibrations in the SD well of 19OHg
Microscopic analysis of quadrupole-octupole shape evolution
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Nomura Kosuke
2015-01-01
Full Text Available We analyze the quadrupole-octupole collective states based on the microscopic energy density functional framework. By mapping the deformation constrained self-consistent axially symmetric mean-field energy surfaces onto the equivalent Hamiltonian of the sdf interacting boson model (IBM, that is, onto the energy expectation value in the boson coherent state, the Hamiltonian parameters are determined. The resulting IBM Hamiltonian is used to calculate excitation spectra and transition rates for the positive- and negative-parity collective states in large sets of nuclei characteristic for octupole deformation and collectivity. Consistently with the empirical trend, the microscopic calculation based on the systematics of ?2 – ?3 energy maps, the resulting low-lying negative-parity bands and transition rates show evidence of a shape transition between stable octupole deformation and octupole vibrations characteristic for ?3-soft potentials.
Deformation Properties of Unbound Granular Aggregates
Uthus, Lillian
2007-01-01
This thesis discusses the resilient and permanent deformation properties of unbound granular aggregates for use in road structures. One of the objectives of the thesis is to identify the influence of the physical properties of the aggregate grains, such as grain size, grain shape, surface texture, mineralogy and mechanical strength through cyclic load triaxial testing. A second objective is to study the effect of water on the deformation properties of materials as well as their frost suscepti...
Petrophysical Properties of Deformed Sandstone Reservoir
Shekari-Namin, Saeideh
2012-01-01
Small scale deformation structures that mostly occur in highly porous rocks are called deformation bands. Petrophysical characteristics of deformation bands are different from those of host rock and they can act as barriers or conduit to fluid flow. The effect on fluid flow is the most important property of these structures which is essential in many geological fields; for instance oil & gas, CO2 storage and ground water flow, when permeability and capillary pressure are the tw...
International Nuclear Information System (INIS)
The energy levels and reduced probabilities of electric dipole, quadrupole and octupole transitions measured in the Coulomb excitation of 226Ra are analyzed in the framework of the soft axial-symmetric rotator model with quadrupole and octupole deformations. The calculated values are in good agreement with experimental data. (author). 11 refs., 2 figs
Search for octupole correlations in 147Nd
Ruchowska, E.; Mach, H.; Kowal, M.; Skalski, J.; P?óciennik, W. A.; Fogelberg, B.
2015-09-01
Properties of excited states in 147Nd have been studied with the multispectra and ? ? coincidence measurements. Twenty-four new ? lines and three new levels have been introduced into the level scheme of 147Nd. Using the advanced time-delayed ? ? ? (t ) method, we measured lifetimes of eight excited levels in 147Nd, populated via the ? decay of 147Pr. We have determined reduced transition probabilities for 30 ? transitions. Multidimensional potential energy surface calculations performed for 147Nd suggest two single-quasiparticle configurations with nonzero octupole deformation, with K =1 /2 and K =5 /2 . Our calculations also predict a sizable value of the electric dipole moment | D0|=0.26 e fm for this nucleus, while experimentally, a lower limit of | D0|?0.02 e fm has been evaluated for the supposed K =1 /2 parity doublet. In contrast to the theoretical results, we do not observe the parity doublet bands with K =5 /2 . This, and the lack of theoretically expected E 1 strength in Nd,149147 may signal some poorly understood structural effect in the odd-N lanthanides.
Magnetic properties of cyclically deformed austenite
Das, Arpan
2014-06-01
In meta-stable austenitic stainless steels, low cycle fatigue deformation is accompanied by a partial stress/strain-induced solid state phase transformation of paramagnetic ?(fcc) austenite phase to ferromagnetic ?/(bcc) martensite. The measured characteristic of magnetic properties, which are the saturation magnetization, susceptibility, coercivity, retentivity, and the area under the magnetic hysteresis loop are sensitive to the total strain amplitude imposed and the corresponding material behaviour. The morphologies and nucleation characteristics of deformation induced martensites (i.e., ?(hcp), ?/(bcc)) have been investigated through analytical transmission electron microscope. It has been observed that deformation induced martensites can nucleate at a number of sites (i.e., shear band intersections, isolated shear bands, shear band-grain boundary intersection, grain boundary triple points, etc.) through multiple transformation sequences: ?(fcc)??(hcp), ?(fcc)??(hcp)??/(bcc), ?(fcc)? deformation twin ??/(bcc) and ?(fcc)??/(bcc).
Improvements on the present theoretical understanding of octupole correlations
Directory of Open Access Journals (Sweden)
Robledo L.M.
2014-03-01
Full Text Available Some intriguing results, obtained in a recent survey of octupole properties for all even-even nuclei, are reanalyzed in order to understand the origin of the strong disagreement with experimental data and/or the strange behaviours observed. The limitations of the rotational formula to describe E1 and E3 transition strengths are discussed as well as the role played by octupole-quadrupole coupling in some specific nuclei.
Magnetic properties of cyclically deformed austenite
Energy Technology Data Exchange (ETDEWEB)
Das, Arpan, E-mail: dasarpan1@yahoo.co.in
2014-06-01
In meta-stable austenitic stainless steels, low cycle fatigue deformation is accompanied by a partial stress/strain-induced solid state phase transformation of paramagnetic ?(fcc) austenite phase to ferromagnetic ?{sup /}(bcc) martensite. The measured characteristic of magnetic properties, which are the saturation magnetization, susceptibility, coercivity, retentivity, and the area under the magnetic hysteresis loop are sensitive to the total strain amplitude imposed and the corresponding material behaviour. The morphologies and nucleation characteristics of deformation induced martensites (i.e., ?(hcp), ?{sup /}(bcc)) have been investigated through analytical transmission electron microscope. It has been observed that deformation induced martensites can nucleate at a number of sites (i.e., shear band intersections, isolated shear bands, shear band–grain boundary intersection, grain boundary triple points, etc.) through multiple transformation sequences: ?(fcc)??(hcp), ?(fcc)??(hcp)??{sup /}(bcc), ?(fcc)? deformation twin ??{sup /}(bcc) and ?(fcc)??{sup /}(bcc). - Highlights: • LCF tests were done at various strain amplitudes of 304LNSS. • Quantification of martensite was done through ferritecope. • Magnetic properties were characterised through VSM. • Correlation of magnetic properties with the cyclic plastic response was done. • TEM was done to investigate the transformation micro-mechanisms.
Magnetic properties of cyclically deformed austenite
International Nuclear Information System (INIS)
In meta-stable austenitic stainless steels, low cycle fatigue deformation is accompanied by a partial stress/strain-induced solid state phase transformation of paramagnetic ?(fcc) austenite phase to ferromagnetic ?/(bcc) martensite. The measured characteristic of magnetic properties, which are the saturation magnetization, susceptibility, coercivity, retentivity, and the area under the magnetic hysteresis loop are sensitive to the total strain amplitude imposed and the corresponding material behaviour. The morphologies and nucleation characteristics of deformation induced martensites (i.e., ?(hcp), ?/(bcc)) have been investigated through analytical transmission electron microscope. It has been observed that deformation induced martensites can nucleate at a number of sites (i.e., shear band intersections, isolated shear bands, shear band–grain boundary intersection, grain boundary triple points, etc.) through multiple transformation sequences: ?(fcc)??(hcp), ?(fcc)??(hcp)??/(bcc), ?(fcc)? deformation twin ??/(bcc) and ?(fcc)??/(bcc). - Highlights: • LCF tests were done at various strain amplitudes of 304LNSS. • Quantification of martensite was done through ferritecope. • Magnetic properties were characterised through VSM. • Correlation of magnetic properties with the cyclic plastic response was done. • TEM was done to investigate the transformation micro-mechanisms
The octupoles take pole position
2002-01-01
The first preseries octupole magnet was delivered to CERN in December 2001. Hooked up to a main quadrupole magnet, its function will be to correct imperfections in the beams. The LHC will be fitted with about 5000 corrector magnets, whose task it will be to provide maximum precision in beam collisions.
AGS correction quadrupoles and octupoles
International Nuclear Information System (INIS)
A pole-face design is presented for a set of correction quadrupoles and a set of correction octupoles required in the Brookhaven AGS. The pole-face design consists of a circular pole which is terminated by radial lines tangent to the circle. The radius of the circle is chosen to cause the lowest undesired multipole present to vanish. (U.S.)
Studies of electric dipole moments in the octupole collective regions of heavy Radiums and Bariums
Hoff, P; Kaczarowski, R
2002-01-01
%IS386 %title\\ \\It is proposed to study the electric dipole moments in the regions of octupole collective Ra-Th and Ba-Ce nuclei by means of Advanced Time-Delayed (ATD) $\\beta\\gamma\\gamma(t)$ method with a primary goal to provide new and critical data on the properties of E1 moments. The proposal focuses on the nuclei of $^{225,226,229}$Ra, $^{229,233}$Th and $^{149,150}$Ba.\\ \\The ATD $\\beta\\gamma\\gamma$(t) method was first tested at ISOLDE as part of the IS322 study of Fr-Ra nuclei at the limits of octupole deformation region. The results have greatly increased the knowledge of electric dipole moments in the region and demonstrated that new and unique research capabilities in this field are now available at ISOLDE. Based on the experience and new systematics, we propose a specialized study with the aim to determine the missing key aspects of the E1 moment systematics. We propose : \\begin{enumerate}[a)] \\item to measure the lifetimes of the 1$_{1}^{-}$ and 3$_{1}^{-}$ states in $^{226}$Ra with $\\sim$15\\% prec...
Octupole shapes and shape changes at high spins in the Z?58, N?88 nuclei
International Nuclear Information System (INIS)
The shapes of rotating Xe, Ba, Ce, Nd, and Sm nuclei (84?N?94) are calculated using the cranking model with the Woods-Saxon average potential and pairing. The lightest isotopes of Xe and Ba have nearly spherical ground states, but develop octupole and quadrupole deformations under rotation which remain up to very high spins. The ground states of the heavier isotopes have octupole and quadrupole deformations which persist up to medium spins (I?12?). At higher spins, a shape transition is predicted to reflection-symmetric aligned many-quasiparticle configurations
Deformation Properties of TiNi Shape Memory Alloy
Tobushi, H.; LIN, P.; Tanaka, K.; Lexcellent, C.; Ikai, A.
1995-01-01
In order to describe the deformation properties due to the martensitic transformation and the R-phase transformation of TiNi shape memory alloy, a thermomechanical constitutive equation considering the volume fractions of induced phases associated with both transformations is developed. The proposed constitutive equation expresses well the properties of the shape memory effect, pseudoelasticity and recovery stress.
Plastic properties of cold-deformed ironbased sintered materials
Directory of Open Access Journals (Sweden)
K. Zar?bski
2010-07-01
Full Text Available Cold plastic forming of sintered metal powders has limited practical application because of, among others, the deformation degree andinitial porosity of preforms. Cold forming is combined with a very drastic drop of plastic properties observed in final products. One of the methods that enable regaining the lost plasticity is annealing of sinters after deformation at temperatures above the recrystallisation point. The results of the investigations were presented which aimed at the determination of an effect that the annealing conditions of colddeformed sintered metal powder can have on its structure and mechanical properties. Special attention was drawn to a combined effect of the deformation degree and heat treatment temperature on final plastic properties of the sinters and on their ultimate tensile strength.
Magnetic properties of single-domain powders after plastic deformation
International Nuclear Information System (INIS)
Magnetic properties of fine-dispersed powders of nickel, fcc cobalt and Co-alloys containing 46 and 51 weight % have been investigated. Single-domain powder plastic deformation proved to lead to magnetic property changes in fcc and hcp transformation materials (nickel-Co). In isotropic samples residual magnetisation magnitude and powder coercitivity strength are decreasing, alongside with a shift of hysteresis frequent cycles along the axis of ordinates. In structural samples residual magnetisation anisotropy is increasing. It points to the uniaxial anisotropy appearing in particles. A crystal structure model of deformed particles is presented which provide magnetic uniaxiality
q-deformed noncommutative cat states and their nonclassical properties
Dey, Sanjib
2015-01-01
We study several classical like properties of q-deformed nonlinear coherent states as well as nonclassical behaviours of q-deformed version of the Schrodinger 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 utilising cat states in noncommutative space over the standard quantum mechanical spaces have been reported here. For instance, the q-deformed parameter has been utilised 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.
q -deformed noncommutative cat states and their nonclassical properties
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.
DEFF Research Database (Denmark)
Jakobsen, Bo
2006-01-01
The main goal of the study presented in this thesis was to perform in-situ investigations on deformation structures in plastically deformed polycrystalline copper at low degrees of tensile deformation (<5%). Copper is taken as a model system for cell forming pure fcc metals. Anovel synchrotron-radiation based technique High Angular Resolution 3DXRD has been developed at the 1-ID beam-line at the Advanced Photon Source. The technique extents the 3DXRD approach, to 3D reciprocal space mapping with a resolution of ? 1 · 10?3Å?1 and allows for in-situmapping of reflections from deeply-embedded individual grains in polycrystalline samples during tensile deformation. We have shown that the resulting 3D reciprocal space maps from tensile deformed copper comprise a pronounced structure, consisting of bright sharp peaks superimposed on a cloud of enhanced intensity. Based on the integrated intensity, the width of the peaks, and spatial scanning experiments it is concluded that the individual peaks arise from individual dislocation-free regions (the subgrains) in the dislocation structure. The cloud is attributed to the dislocation rich walls. Samples deformed to 2% tensile strain were investigated under load, focusing on grains that have the tensile direction close to the h100i direction. It was found that the individual subgrains, on average, are subjected to a reduction of the elastic strain with respect to the mean elastic strain of the grain. The walls are equivalently subjected to an increased elastic strain. The distribution of the elastic strains between the individual subgrains is found to be wider than the distribution of strains within the individual subgrains. The average properties are consistent with a composite type ofmodel. The details, however, show that present understanding of asymmetrical line broadening have to be reconsidered. Based on continuous deformation experiments, it is found that the dislocation patterning takes place during the deformation, and that a subgrain structure appears from the moment where plastic deformation is detected. By investigating samples under stress relaxation conditions, and unloading, it is found that the overall dislocation structure only depends on the maximum obtained flow stress. However, some changes in orientation and internal strain distribution between the subgrains were observed after the unloading. An in-situ stepwise straining experiment of a pre-deformed sample was performed, allowing for investigation of individual subgrains during straining. The result indicates that the cell refinement process generally does not take place through simple subgrain breakups. Surprisingly, the dislocation structure shows intermittent behavior, with subgrains appearing and disappearing with increasing strain, suggesting a dynamical development of the structure.
Strength and Deformation Properties of Tertiary Clay at Moesgaard Museum
Kaufmann, Kristine Lee; Nielsen, Benjaminn Nordahl; Augustesen, Anders Hust
2010-01-01
The tertiary clay at Moesgaard Museum near Aarhus in the eastern part of Jutland in Denmark is a highly plastic, glacially disturbed nappe of Viborg Clay. The clay is characterised as a swelling soil, which could lead to damaging of the building due to additional heave of the soil. To take this characteristic, as well as the strength and deformation properties, into account during the design phase, two consolidation tests and one triaxial test have been conducted. This paper evaluates the res...
Strength and Deformation Properties of Tertiary Clay at Moesgaard Museum
DEFF Research Database (Denmark)
Kaufmann, Kristine Lee; Nielsen, Benjaminn Nordahl; Augustesen, Anders Hust
2010-01-01
The tertiary clay at Moesgaard Museum near Aarhus in the eastern part of Jutland in Denmark is a highly plastic, glacially disturbed nappe of Viborg Clay. The clay is characterised as a swelling soil, which could lead to damaging of the building due to additional heave of the soil. To take this characteristic, as well as the strength and deformation properties, into account during the design phase, two consolidation tests and one triaxial test have been conducted. This paper evaluates the result...
Processing microstructure property relationships in severely deformed tantalum
International Nuclear Information System (INIS)
Bars of as-cast, large grained and highly textured Ta were deformed by multipass equal channel angular extrusion (ECAE) at room temperature to strains of 4.6 through 90 deg. die-angle tooling. The ability of ECAE processing to produce a uniform fine-grained microstructure with homogenous deformation characteristics is investigated. Comparisons of the microstructure and mechanical properties after four consecutive extrusions via route C (180 deg. rotation between passes) and E (2C, 90 deg. rotation then 2C) are made in both the as-worked (submicron-scale grains) and recrystallized (micron-scale grains) states. It is shown that the as-worked grain size levels out at 200-300 nm after four passes. The recrystallized grain size after two to four passes is ?10-15 ?m with microstructural uniformity that is dependent on the microstructural uniformity in the starting material. It is also demonstrated that four pass ECAE processing of as-cast large grained BCC materials is not necessarily enough to homogenize texture. A pre-processing step with combined severe plastic deformation and recrystallization improves microstructural uniformity and lessens texture gradients in subsequent deformation processing steps
Microstructure, properties and hot deformability of the new maraging steels
Directory of Open Access Journals (Sweden)
S.J. Pawlak
2008-07-01
Full Text Available Purpose: The effects of relevant metallurgical factors on the structure, fracture mode and properties of the high cobalt and cobalt free maraging steel has been studied. The aim was to better understand structure-property relations and enhance mechanical properties of the steels. To provide data needed for production and manufacturing technology, the high temperature deformability using physical simulation method was used.Design/methodology/approach: To study structure-property relation, broad range of the experimental techniques was used: quantitative metallography, X-ray diffraction phase analysis, transmission electron microscopy and SEM fractography. The flow properties in the range of hot working processes were determined by physical simulation approach, using Gleeble 3800 system.Findings: The cobalt-free maraging steel proved to be a valuable structural steel. At much higher fracture toughness it had only about 100 MPa lower yield stress, compared to that of high cobalt steel. Fracture surface morphologies were highly dependent on the steel grade and type of the mechanical test. The hot stress-strain characteristics were established for cobalt free maraging steel and compared to that of a stainless steel.Research limitations/implications: To fully evaluate potential field of applications, deeper comparative studies of the high cobalt and cobalt-free maraging steels are needed, particularly fracture modes and service properties of some parts.Practical implications: Very high mechanical properties and fracture toughness values obtained for the steels studied, make them suitable for advanced structural applications. The studies on the hot deformation behaviour of the steels are of practical value for the hot working process development.Originality/value: Detailed evaluation of the metallurgical purity, microstructure and fracture modes, allowed for better understanding of the microstructure-property relationships in selected high strength steels. The results obtained are of practical value for the development, production and manufacture of the high strength maraging steels with improved properties.
Evolution of ground-state quadrupole and octupole stiffnesses in even-even barium isotopes
Wang, Hua-Lei; Yang, Jie; Liu, Min-Liang; Xu, Fu-Rong
2015-08-01
Quadrupole and octupole stiffnesses in the ground states of even-even Ba-150112 isotopes have been systematically investigated by means of potential-energy-surface calculations. The calculations are carried out in both (?2,? ,?4 ) and (?2,?3,?4,?5) deformation spaces with the inclusion of triaxial and reflection-asymmetric shape degrees of freedom, respectively. The present results are compared with previous calculations and available experiments. The shape instabilities are evaluated by analyzing the potential energy curves with respect to both the quadrupole and octupole deformations, which is consistent with the previous discussions predicting the ? softness or triaxiality and octupole instability. In addition, taking the near-drip-line 114Ba nucleus as an example, we briefly investigate the effects of potential parameters (e.g., the strength of the spin-orbit potential ? , and the nuclear surface diffuseness a ) on the deformation energy curve, showing almost negligible modifications of nuclear shape and stiffness but considerable changes in the depth of the minimum and the height of the fission barrier (which may be very important for the study of heavy and superheavy nuclei).
Rock mass deformation properties of closely jointed basalt
International Nuclear Information System (INIS)
The deformational behavior of the Columbia River basalt is being investigated as part of a comprehensive site characterization program intended to determine the feasibility of constructing a nuclear waste repository in basalt at Hanford, Washington. Direct field measurements were conducted in a 2-m cube of basalt to obtain truly representative rock mass deformation properties. Load was applied to the test block in three orthogonal directions through the use of flat jacks in two perpendicular planes and a cable anchor system in the third. This configuration allowed the block to be placed in a simulated triaxial stress state at stress levels up to 12.5 MPa. The deformation at the center of the test block was monitored through the use of an optical measurement system developed for this project. The results indicate that the vertically oriented columnar joints have a significant influence on the deformation behavior of the basalt. The modulus in the direction parallel to the column axis was approx. 30 GPa, while the modulus value perpendicular to the columns was approx. 20 GPa. Laboratory measurements of intact specimens taken from this area yielded a value of 80 GPa with no indication of anisotropy. Hysteresis was observed in all loading cycles, but was distinctly more pronounced perpendicular to the column axis, indicative of significant joint displacement in this direction. The results of this test represent the first true rock mass modulus data obtained in closely jointed rock on a large scale. These measurement methods have eliminated many of the ambiguities associated with borehole jacking and surface measurement techniques
Elliott, Sara; Eichhubl, Peter; Landry, Chris
2014-05-01
Deformation bands tend to restrict flow perpendicular to the bands through the combined effects of porosity reduction, mechanical grain size reduction, and preferred cementation relative to the adjacent host rock. Thus, deformation bands may impart a permeability anisotropy to reservoir rocks. Deformation bands that occur in association with reservoir scale faults can impact reservoir-scale fluid flow and fault seal behavior. Using a combination of textural imaging including SEM-based cathodoluminescence imaging, compositional analysis, and lab petrophysics, this study is designed to (1) assess the effects of coupled chemical and mechanical processes leading to deformation localization in deformation bands and (2) to quantify the effect of these processes on single and multiphase fluid flow. While the effects of mechanical processes including grain translation, rotation, and breakage have been described in detail, chemical reactions affecting flow properties have received less attention. Such chemical reactions include the precipitation of carbonate and quartz cement, dissolution and albitization of feldspar, and the neoformation and infiltration of clay minerals. It is shown that the mechanical process of deformation localization is strongly controlled by chemical processes including pre-kinematic pore-filling cement, syn-kinematic cement filling intra- and transgranular fractures, and stress-enhanced dissolution reactions. Prekinematic cements reduce the strength contrast between grain and aggregate thus favoring deformation localization into narrow, well defined deformation bands. Prekinematic cementation and compaction may even favor thoroughgoing opening mode fractures and prevent localization of deformation into deformation band. Synkinematic cements within deformation bands will result in local strain hardening of bands and thus oppose further deformation localization with increasing strain. Examples will be presented from the Mesozoic clastic sequence of the western US to illustrate these processes.
Neoclassical currents in the Wisconsin Levitated Octupole
International Nuclear Information System (INIS)
Neoclassical transport theory predicts the existence of bootstrap current in collisionless plasmas with a significant population of trapped particles. This unidirectional current flows along field lines, and is generated by the balancing of ion-electron friction forces with the viscous forces between trapped and untrapped like particles. The current is driven by gradients in the plasma pressure and temperature. Previous work has identified the existence of bootstrap current in the Wisconsin Levitated Octupole, and this discovery of bootstrap current in the octupole naturally leads to the question of why previous experiments were unsuccessful in their endeavors to identify this current. The original motivation for this thesis was to address that question, by investigating the effects on bootstrap current caused by ohmic currents, plasma fluctuations, and rf fields. Ohmic currents, while naturally present in tokamaks, can be introduced in the octupole, independent of the usual operating procedure, and can be adjusted to be of the same order of magnitude as the expected diamagnetic and parallel currents. The interaction, if any, of bootstrap current and ohmic current can thus be determined without the problem of a large ohmic current masking the neoclassical current. Rf fields can be driven in the octupole plasma with little or no plasma heating. Any anomalous effects on the parallel currents, due to the existence of the rf fields, can then be determined. This thesis consists of four parts: the experimental apparatus and the plasma diagnostics used in these studies; the general theory of neoclassical currents (excluding field errors) and how it is applied to the octupole; the experimental results of this investigation; and a brief discussion of the conclusions that can be inferred from the data
Evidence for octupole vibration in the superdeformed well of {sup 190}Hg from eurogam
Energy Technology Data Exchange (ETDEWEB)
Crowell, B.; Carpenter, M.P.; Janssens, R.V.F. [and others
1995-08-01
Gammasphere experiments in 1993-94 brought to light the existence of an excited superdeformed (SD) band in {sup 190}Hg with the unusual property of decaying entirely to the lowest (yrast) SD band over 3-4 transitions, rather than to the normally deformed states as is usually the case in the A {approximately} 150 and A {approximately} 190 regions of superdeformation. Although M1 transitions between signature-partner SD bands were previously observed in {sup 193}Hg, no such mechanism was available to explain the situation in the even-even nucleus {sup 190}Hg, whose yrast SD band has no signature partner. The best explanation appears to lie in long-standing theoretical predictions that the SD minimum in the potential energy surface would be quite soft with respect to octupole vibrations. This would lead to enhanced E1 transitions connecting the one-phonon and zero-phonon states. The data and this interpretation were published. A shortcoming of the Gammasphere experiments was that they did not allow the definitive measurement of the energies of the gamma-ray transitions connecting the two bands, due to the very weak population of the excited band ({approximately}0.05% of the {sup 190}Hg channel) and also partly, we believed, to the angular distributions of the transitions, which were peaked near 90 degrees, where Gammasphere had few detectors.
Transient deformation properties of Zircaloy for LOCA simulation. Final report
International Nuclear Information System (INIS)
The creep/creep rupture anisotropic properties of Zircaloy were determined and compared by analytical techniques with ramp-pressure and ramp-temperature test results. Tests were performed over the temperature range of 6000F (5890K) to 22000F (14770K) with the emphasis on the 8000F (7000K) to 20000F (13660K) temperature levels in low pressure air (6.5 x 10-5 atm) and in a 1 atm mixture of 20% oxygen, 80% argon. Stress levels of 60 to 95% of the ultimate tensile stress were used for the majority of the tests at each of the temperature levels tested, with selected tests performed as low as 30% of the ultimate tensile stress. Biaxial and uniaxial testing modes were used to evaluate the anisotropic deformation behavior. The combination of test results and predictive analysis techniques developed as part of this program make it possible to predict the transient deformation of reactor fuel cladding during simulated LOCA conditions. Results include creep/creep rupture strain numerical constitutive relationships out of 120 seconds, computer codes and ramp test data
Transient deformation properties of Zircaloy for LOCA simulation. Final report
Energy Technology Data Exchange (ETDEWEB)
Hann, C.R.; Mohr, C.L.; Busness, K.M.; Olson, N.J.; Reich, F.R.; Stewart, K.B.
1978-03-01
The creep/creep rupture anisotropic properties of Zircaloy were determined and compared by analytical techniques with ramp-pressure and ramp-temperature test results. Tests were performed over the temperature range of 600/sup 0/F (589/sup 0/K) to 2200/sup 0/F (1477/sup 0/K) with the emphasis on the 800/sup 0/F (700/sup 0/K) to 2000/sup 0/F (1366/sup 0/K) temperature levels in low pressure air (6.5 x 10/sup -5/ atm) and in a 1 atm mixture of 20% oxygen, 80% argon. Stress levels of 60 to 95% of the ultimate tensile stress were used for the majority of the tests at each of the temperature levels tested, with selected tests performed as low as 30% of the ultimate tensile stress. Biaxial and uniaxial testing modes were used to evaluate the anisotropic deformation behavior. The combination of test results and predictive analysis techniques developed as part of this program make it possible to predict the transient deformation of reactor fuel cladding during simulated LOCA conditions. Results include creep/creep rupture strain numerical constitutive relationships out of 120 seconds, computer codes and ramp test data.
Fluid and ionic transport properties of deformed salt rock
International Nuclear Information System (INIS)
This is a final report on work done on the transport properties of salt during the period 1 January 1984 to 30 June 1985. This work was directed largely at the measurement of creep-induced permeability in salt rock, at determining the permeability persistence/decay characteristics of creep-dilated salt rock under hydrostatic conditions, and at ion migration/retention experiments on both deformed and undeformed material. The permeability work was carried out using both gas (argon) and brine, and involved the design and construction of corresponding permeametry systems for use in conjunction with dilatometric triaxial testing apparatus. Ion migration/retention studies involved the use of contaminant species such as Sr2+, Cs+, Fe3+ and TcO4
Properties of highly deformed tungsten alloys for vacuum technology
International Nuclear Information System (INIS)
The powder metallurgical production and applications of tungsten alloys are briefly reviewed with emphasis on wires containing dispersed thoria for applications under vacuum. The properties of pure and Al-K-Si doped tungsten wire, of doped tungsten wire with 1 and 2% thoria added as powder and as thorium hydrosol, of undoped W2Th02, W2Th02 sol, and of W5Re are compared and discussed. The tensile strength, elongation and brittle-ductile transition temperature are given for W2Th02 as a function of deformation history up to 14000C. The effect of annealing in hydrogen at up to 24000C on the mechanical properties of 06. mm diameter wire of tungsten and eight tungsten materials has been determined. In addition to the determination of recrystallisation temperatures and electric conductivities, the results of creep tests are discussed. Sag tests were carried out on the wires and creep curves were recorded at 24500C in hydrogen and in vacuum. The results are correlated with scanning electron micrographs. Finally, the mechanical properties of 0.1 mm thick foil of pure and Al-K-Si doped tungsten, W10Re, and W2Th02 are described. (author)
International Nuclear Information System (INIS)
The evolution of crystallographic texture in a nanocrystalline nickel–20 wt% cobalt alloy has been investigated for deformation up to large strains. The effect of texture on magnetic properties has been evaluated. The material shows characteristic copper-type texture at large strain levels. Microstructural examinations indicate that the evolution of texture is assisted by deformation-induced grain growth. The values of saturation magnetization and coercivity have been correlated with the crystallographic texture and grain size. - Highlights: • The deformation of a nanocrystalline nickel-20 wt% cobalt alloy, to large strains, leads to a characteristic copper-type rolling texture. • Dislocation based slip process is evident from the deformed microstructures at the later stages of deformation, while grain boundary assisted mechanisms are active during the initial stages. • The activity of dislocation at higher strain levels is facilitated by deformation-induced grain growth. • The evolution of magnetic properties is dependent on the deformation texture, while the effect of grain size is insignificant
International Nuclear Information System (INIS)
The results of the comprehensive research of the deformation micropicture and mechanical properties of Ni-Ti based alloys are presented. The research of the microheterogeneous deformation on the small bases with the smallest base of 10 micron were made with the help of the elaborated automation method of the deformation measurement in the comparison with different metals. Mechanical properties had been studied on the basis of the deformation diagram research on the results of the deformation measurement with the precision up to 3.10-5. The distinctive peculiarities of the microheterogeneous deformation of Ni-Ti based alloys were established. The process of the deformation in the microvolumes is extremely heterogeneous. The microheterogeneity of the residual microdeformation distribution is being preserved with the full restoration of the shape under the temperature influence. This explains the difference in mechanical properties of alloys in their proper state and after deformation and restoration of shape. It is shown that deformation of alloys takes place on the account of shifting processes and martensitic transformations. The relation between these micromechanisms of deformations depends on the value of deformation. Heterogeneity of distribution of microdeformation causes the appearance of elastic hysteresis and change of elasticity module in the process of loading and unloading. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Kuksa, L.V. [Volgograd Architectural Building Acad. (Russian Federation). Strength of Mater. Dept.; Fatkullina, L.P. [All-Russia Inst. of Light Alloys, Moscow (Russian Federation). Shape Memory Alloys Dept.
1995-12-01
The results of the comprehensive research of the deformation micropicture and mechanical properties of Ni-Ti based alloys are presented. The research of the microheterogeneous deformation on the small bases with the smallest base of 10 micron were made with the help of the elaborated automation method of the deformation measurement in the comparison with different metals. Mechanical properties had been studied on the basis of the deformation diagram research on the results of the deformation measurement with the precision up to 3.10{sup -5}. The distinctive peculiarities of the microheterogeneous deformation of Ni-Ti based alloys were established. The process of the deformation in the microvolumes is extremely heterogeneous. The microheterogeneity of the residual microdeformation distribution is being preserved with the full restoration of the shape under the temperature influence. This explains the difference in mechanical properties of alloys in their proper state and after deformation and restoration of shape. It is shown that deformation of alloys takes place on the account of shifting processes and martensitic transformations. The relation between these micromechanisms of deformations depends on the value of deformation. Heterogeneity of distribution of microdeformation causes the appearance of elastic hysteresis and change of elasticity module in the process of loading and unloading. (orig.).
DEFF Research Database (Denmark)
Jakobsen, Bo
2006-01-01
The main goal of the study presented in this thesis was to perform in-situ investigations on deformation structures in plastically deformed polycrystalline copper at low degrees of tensile deformation (<5%). Copper is taken as a model system for cell forming pure fcc metals. Anovel synchrotron-radiation based technique High Angular Resolution 3DXRD has been developed at the 1-ID beam-line at the Advanced Photon Source. The technique extents the 3DXRD approach, to 3D reciprocal space mapping with...
Calvo, Florent; Champenois, Caroline; YURTSEVER, Ersin
2009-01-01
The stable structures and melting properties of ion clouds in isotropic octupole traps are investigated using a combination of semi-analytical and numerical models, with a particular emphasis at finite size scaling effects. Small-size clouds are found to be hollow and arranged in shells corresponding approximately to the solutions of the Thomson problem. The shell structure is lost in clusters containing more than a few thousands of ions, the inner parts of the cloud becomin...
Spectroscopy of quadrupole and octupole states in rare-earth nuclei from a Gogny force
Nomura, K; Robledo, L M
2015-01-01
Collective quadrupole and octupole states are described in a series of Sm and Gd isotopes within the framework of the interacting boson model (IBM), whose Hamiltonian parameters are deduced from mean field calculations with the Gogny energy density functional. The link between both frameworks is the ($\\beta_2\\beta_3$) potential energy surface computed within the Hartree-Fock-Bogoliubov framework in the case of the Gogny force. The diagonalization of the IBM Hamiltonian provides excitation energies and transition strengths of an assorted set of states including both positive and negative parity states. The resultant spectroscopic properties are compared with the available experimental data and also with the results of the configuration mixing calculations with the Gogny force within the generator coordinate method (GCM). The structure of excited $0^{+}$ states and its connection with double octupole phonons is also addressed. The model is shown to describe the empirical trend of the low-energy quadrupole and o...
Inami, T.; Michimura, S.; Hayashi, Y.; Matsumura, T.; Sera, M.; Iga, F.
2014-07-01
We carried out a high-resolution x-ray diffraction experiment on Ce0.7La0.3B6 that exhibits staggered order of 4f octupole moments below TO=1.4 K. Theoretically, ferroquadrupole moments that accompany the antiferro-octupole order and a resultant rhombohedral deformation of the cubic lattice were predicted. In contrast, experimentally, no direct evidence of the rhombohedral lattice has been obtained. We observe the splitting of Bragg peaks below TO and find that the unit cell is a rhombohedron being elongated along the [111] axis. The response of rhombohedral domains to magnetic fields also well agrees with theoretical calculations. A particular outcome of this experiment is that the magnitude of the induced quadrupole moments is precisely evaluated from the obtained shear strain. Using this result, the magnitude of the hidden octupole moments is also discussed.
Changes in microstructure and physical properties of skutterudites after severe plastic deformation.
Czech Academy of Sciences Publication Activity Database
Rogl, G.; Grytsiv, A.; Buršík, Ji?í; Horky, J.; Anbalagan, R.; Bauer, E.; Mallik, R.Ch.; Rogl, P.; Zehetbauer, M.
2015-01-01
Ro?. 17, ?. 5 (2015), s. 3715-3722. ISSN 1463-9076 Institutional support: RVO:68081723 Keywords : physical properties * plastic deformation * TEM, SEM Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.493, year: 2014
Octupole deformation in neutron-rich barium isotopes
International Nuclear Information System (INIS)
Partial decay schemes for the very neutron-rich nuclei /sup 142,144/Ba and /sup 146/Ba have been determined by the study of ?-? coincidences in /sup 252/Cf fission fragments. Interlaced positive- and negative-parity levels connected by fast electric dipole transitions are observed in /sup 144/Ba and /sup 146/Ba above spin 7h. This is similar to the situation in some light actinide nuclei, where the data have been interpreted in terms of reflection-asymmetric shapes
Food gels filled with emulsion droplets : linking large deformation properties to sensory perception
Sala, G.
2007-01-01
Key words: polymer gels, particle gels, emulsion, large deformation, friction, sensory This thesis reports studies on the large deformation and lubrication properties of emulsion-filled gels and the way these properties are related to the sensory perception of the gels. The design of the studies included polymer and particle gels containing oil droplets of which the interaction with the gel matrix was varied, resulting in droplets either bound or unbound to the matrix. The unique combinatio...
Measuring the full transverse beam matrix using a single octupole
Ögren, J.; Ruber, R.; Ziemann, V.; Farabolini, W.
2015-07-01
We propose a method to fully determine the transverse beam matrix using a simple setup consisting of two steering magnets, an octupole field and a screen. This works in principle for any multipole field, i.e., sextupole, octupole magnet or a radio frequency structure with a multipole field. We have experimentally verified the method at the Compact Linear Collider Test Facility 3 at CERN using a Compact Linear Collider accelerating structure, which has an octupole component of the radio frequency fields. By observing the position shifts of the beam centroid together with changes in transverse beam size on a screen, we determined the full transverse beam matrix, with all correlations.
Concentration and deformation dependences of Mo-Cu and Mo-Ni-Cu composites mechanical properties
International Nuclear Information System (INIS)
Mechanical properties of sintered composites were investigated in dependence on phase composition and deformation. The ultimate strength and yield limit of Mo-Cu and Mo-Cu-Ni compositions do not depend on the reinforcing phase volume. It is shown that plastic deformation of these materials leads to an increase in their strength and plasticity; the strengthening process occurs in several stages. It is found out that when the deformation degree is above 90%, the strengthening coefficient is on the average thrice as high; anisotropy of mechanical properties is practically absent; the character of their dependence on the volume of the reinforcing particles remains unchanged
String field theory. Algebraic structure, deformation properties and superstrings
International Nuclear Information System (INIS)
This thesis discusses several aspects of string field theory. The first issue is bosonic open-closed string field theory and its associated algebraic structure - the quantum open-closed homotopy algebra. We describe the quantum open-closed homotopy algebra in the framework of homotopy involutive Lie bialgebras, as a morphism from the loop homotopy Lie algebra of closed string to the involutive Lie bialgebra on the Hochschild complex of open strings. The formulation of the classical/quantum open-closed homotopy algebra in terms of a morphism from the closed string algebra to the open string Hochschild complex reveals deformation properties of closed strings on open string field theory. In particular, we show that inequivalent classical open string field theories are parametrized by closed string backgrounds up to gauge transformations. At the quantum level the correspondence is obstructed, but for other realizations such as the topological string, a non-trivial correspondence persists. Furthermore, we proof the decomposition theorem for the loop homotopy Lie algebra of closed string field theory, which implies uniqueness of closed string field theory on a fixed conformal background. Second, the construction of string field theory can be rephrased in terms of operads. In particular, we show that the formulation of string field theory splits into two parts: The first part is based solely on the moduli space of world sheets and ensures that the perturbative string amplitudes are recovered via Feynman rules. The second part requires a choice of background and determines the real string field theory vertices. Each of these parts can be described equivalently as a morphism between appropriate cyclic and modular operads, at the classical and quantum level respectively. The algebraic structure of string field theory is then encoded in the composition of these two morphisms. Finally, we outline the construction of type II superstring field theory. Specific features of the superstring are the appearance of Ramond punctures and the picture changing operators. The sewing in the Ramond sector requires an additional constraint on the state space of the world sheet conformal field theory, such that the associated symplectic structure is non-degenerate, at least on-shell. Moreover, we formulate an appropriate minimal area metric problem for type II world sheets, which can be utilized to sketch the construction of a consistent set of geometric vertices. The algebraic structure of type II superstring field theory is that of a N = 1 loop homotopy Lie algebra at the quantum level, and that of a N = 1 homotopy Lie algebra at the classical level.
Properties of interfaces and plastic deformation in TiAl.
Czech Academy of Sciences Publication Activity Database
Paidar, Václav
Brno, 2001, s. 424-428. ISBN 80-214-1892-3. [International Conference MSMF /3./. Brno (CZ), 27.06.2001-29.06.2001] Institutional research plan: CEZ:AV0Z1010914 Keywords : intermetallic compounds * modes of plastic deformation * superlattice dislocations * twinning * lamellar microstructure * grain boundaries * compatibility stresses Subject RIV: BM - Solid Matter Physics ; Magnetism
Ground state octupole correlation energy with effective forces
Robledo, L. M.
2015-05-01
The ground state octupole correlation energy is computed with the D1M variant of the Gogny force in different theoretical frameworks and analyzed in detail. First I consider the correlation energy gained at the mean field level by breaking reflection symmetry. Next I consider the energy gain coming from symmetry (parity) restoration and finally I analyze the ground state correlation energy after configuration mixing with axially symmetric octupole states. The impact of the latter on theoretical binding energies indicates that octupole correlations do not affect in a significant way the trend and systematic of binding energies and therefore can not improve the performance of theoretical models in this respect. In particular, the too-large ‘shell gaps’ predicted by self-consistent mean field models and relevant in astrophysics scenarios are not altered by the octupole correlations.
Ground state octupole correlation energies with effective forces
Robledo, Luis M.
2014-01-01
The ground state octupole correlation energy is computed with the D1M variant of the Gogny force in different theoretical frameworks and analyzed in detail. First I consider the correlation energy gained at the mean field level by breaking reflection symmetry. Next I consider the energy gain coming from symmetry (parity) restoration and finally I analyze the ground state correlation energy after configuration mixing with axially symmetric octupole states. The impact of the l...
International Nuclear Information System (INIS)
Evaluation of creep-fatigue is essential in design and life management of high-temperature components in power generation plants. Cyclic deformation may alter creep property of the materials and its consideration may improve predictability of creep-fatigue failure life. To understand them, creep tests were conducted for the materials subjected to cyclic loading and their creep rupture and deformation behaviors were compared with those of as-received materials. Both 316FR and modified 9Cr-1Mo steel were tested. (1) Creep rupture time and elongation generally tend to decrease with cyclic loading in both materials, and especially elongation of 316FR drastically decreases by being cyclically deformed. (2) Amount of primary creep deformation decreases by cyclic loading and the ways to improve its predictability were developed. (3) Use of creep rupture ductility after cyclic deformation, instead of that of as-received material, brought about clear improvement of life prediction in a modified ductility exhaustion approach. (author)
Transient deformation properties of Zircaloy for LOCA simulation. Final report
International Nuclear Information System (INIS)
This experimental data report is Volume 4 of a series of 5 volumes describing the oxidation and deformation rate behavior of Zircaloy cladding under simulated LOCA conditions. It contains listings of strain versus stress, time, and temperature evaluated from the numerical constitutive relationships and the original data used to develop them. This volume also contains listings of the ramp load, pressure, and temperature test data from both current and previous phases of the series, as well as material describing applications of the data
Transient deformation properties of Zircaloy for LOCA simulation. Final report
Energy Technology Data Exchange (ETDEWEB)
Hann, C. R.; Mohr, C. L.; Busness, K. M.; Olson, N. J.; Reich, F. R.; Stewart, K. B.
1980-05-01
This experimental data report is Volume 4 of a series of 5 volumes describing the oxidation and deformation rate behavior of Zircaloy cladding under simulated LOCA conditions. It contains listings of strain versus stress, time, and temperature evaluated from the numerical constitutive relationships and the original data used to develop them. This volume also contains listings of the ramp load, pressure, and temperature test data from both current and previous phases of the series, as well as material describing applications of the data.
Properties of interfaces and plastic deformation in TiAl.
Czech Academy of Sciences Publication Activity Database
Paidar, Václav
Brno : x, 2001 - (Šandera, P.), s. 759-766 ISBN 80-214-1892-3. [International Conference on Materials structure and Micromechanics of Fracture /3./. Brno (CZ), 27.06.2001-29.06.2001] R&D Projects: GA AV ?R IAA1010817; GA MŠk ME 190 Institutional research plan: CEZ:AV0Z1010914 Keywords : intermetallic compounds * modes of plastic deformation * superlattice dislocations * twinning * lamellar microstructure * grain boundaries Subject RIV: BM - Solid Matter Physics ; Magnetism
Directory of Open Access Journals (Sweden)
RahulPandit
2014-06-01
Full Text Available We carry out an extensive numerical study of the dynamics of spiral waves of electrical activation, in the presence of periodic deformation (PD in two-dimensional simulation domains, in the biophysically realistic mathematical models of human ventricular tissue due to (a ten-Tusscher and Panfilov (the TP06 model and (b ten-Tusscher, Noble, Noble, and Panfilov (theTNNP04 model. We first consider simulations in cable-type domains, in which we calculate the conduction velocity $CV$ andthe wavelength $\\lambda$ of a plane wave; we show that PD leads to a periodic, spatial modulation of $CV$ and a temporallyperiodic modulation of $\\lambda$; both these modulations depend on the amplitude and frequency of the PD. We then examine three types of initial conditions for both TP06 and TNNP04 models and show that the imposition of PD leads to a rich variety ofspatiotemporal patterns in the transmembrane potential including states with a single rotating spiral (RS wave, a spiral-turbulence (ST state with a single meandering spiral, an ST state with multiple broken spirals, and a state SA in which all spirals are absorbed at the boundaries of our simulation domain. We find, for both TP06 and TNNP04 models, that spiral-wave dynamics depends sensitively on the amplitude and frequency of PD and the initial condition. We examine how these different types of spiral-wave states can be eliminated in the presence of PD by the application of low-amplitude pulses on square and rectangular control meshes. We suggest specific experiments that can test the results of our simulations.
Determination of the deformation properties of Søvind Marl
DEFF Research Database (Denmark)
GrØnbech, Gitte; Nielsen, Benjaminn Nordahl
2010-01-01
A serie of tests were made to determine the preconsolidation stresses, ??pc, and the consolidation modulus, K, of Søvind Marl, a fissured plastic tertiary clay. The fissures causes a decrease in the stiffness of the Søvind Marl, which can be mistaken for the decrease that happens when the effective stresses in the soil, ??, passes ??pc. The effects of the fissures are assessed, and an estimate of the stress level at which they will compress are made. During the consolidation tests, the effective stress level is raised to more then 24,000 kPa to get a comprehensive description of the preconsolidation of the soil. It is important to know how a strongly preconsolidated soil will deform when reloaded. The deformation parameters of the strongly preconlidated Søvind Marl is determined by unloading/reloading testing. It is found that the stiffness of the Søvind Marl depends of the plasticity index, and one conclusive expression of the consolidation modulus of the Søvind Marl can therefor not be given.
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Vachhani Shraddha J.
2015-01-01
Full Text Available Shear localization is often a failure mechanism in materials subjected to high strain rate deformation. It is generally accepted that the microstructure evolution during deformation and the resulting heterogeneities strongly influence the development of these shear bands. Information regarding the development of local mechanical heterogeneities during deformation is difficult to characterize and as such, constitute is a critical missing piece in current crystal plasticity models. With the recent advances in spherical nanoindentation data analysis, there is now an unprecedented opportunity to obtain insights into the change in local mechanical properties during deformation in materials at sub-micron length scales. In this work, we quantify the evolution of microstructure and local mechanical properties in tantalum under dynamic loading conditions (split Hopkinson pressure bar, to capture the structure- property correlations at the sub-micron length scale. Relevant information is obtained by combining local mechanical property information captured using spherical nanoindentation with complimentary structure information at the indentation site measured using EBSD. The aim is to gain insight into the role of these microstructural features during macroscopic deformation, particularly their influence on the development of mechanical heterogeneities that lead to failure.
Vachhani, Shraddha J.; Mara, Nathan; Livescu, Veronica; Cerreta, Ellen
2015-09-01
Shear localization is often a failure mechanism in materials subjected to high strain rate deformation. It is generally accepted that the microstructure evolution during deformation and the resulting heterogeneities strongly influence the development of these shear bands. Information regarding the development of local mechanical heterogeneities during deformation is difficult to characterize and as such, constitute is a critical missing piece in current crystal plasticity models. With the recent advances in spherical nanoindentation data analysis, there is now an unprecedented opportunity to obtain insights into the change in local mechanical properties during deformation in materials at sub-micron length scales. In this work, we quantify the evolution of microstructure and local mechanical properties in tantalum under dynamic loading conditions (split Hopkinson pressure bar), to capture the structure- property correlations at the sub-micron length scale. Relevant information is obtained by combining local mechanical property information captured using spherical nanoindentation with complimentary structure information at the indentation site measured using EBSD. The aim is to gain insight into the role of these microstructural features during macroscopic deformation, particularly their influence on the development of mechanical heterogeneities that lead to failure.
Structure property correlation: electrochemomechanical deformation in polypyrrole films
International Nuclear Information System (INIS)
Direct electrochemomechanical deformation (ECMD) behavior in the electrodeposited freestanding films of polypyrrole (PPy) doped with naphthalene sulphonic acid (NSA) has been investigated using cyclic voltammetry and cyclic step-voltammetry. It has been found that NSA doped PPy exhibits different film morphology when it was electrodeposited on to the different substrates such as non-corrosive stainless steel, indium-tin-oxide glass and platinum being used as anode. The differential behavior in ECMD characteristics observed on PPy film deposited on different substrates are associated with differential microstructures and porosities of the film as evidenced by scanning electron microscopic observations. An attempt has been made to correlate the effect of film morphology and the relative porosity of the film on the ECMD characteristics in the NSA doped PPy freestanding films
Effect of material property heterogeneity on biomechanical modeling of prostate under deformation
Samavati, Navid; McGrath, Deirdre M.; Jewett, Michael A. S.; van der Kwast, Theo; Ménard, Cynthia; Brock, Kristy K.
2015-01-01
Biomechanical model based deformable image registration has been widely used to account for prostate deformation in various medical imaging procedures. Biomechanical material properties are important components of a biomechanical model. In this study, the effect of incorporating tumor-specific material properties in the prostate biomechanical model was investigated to provide insight into the potential impact of material heterogeneity on the prostate deformation calculations. First, a simple spherical prostate and tumor model was used to analytically describe the deformations and demonstrate the fundamental effect of changes in the tumor volume and stiffness in the modeled deformation. Next, using a clinical prostate model, a parametric approach was used to describe the variations in the heterogeneous prostate model by changing tumor volume, stiffness, and location, to show the differences in the modeled deformation between heterogeneous and homogeneous prostate models. Finally, five clinical prostatectomy examples were used in separately performed homogeneous and heterogeneous biomechanical model based registrations to describe the deformations between 3D reconstructed histopathology images and ex vivo magnetic resonance imaging, and examine the potential clinical impact of modeling biomechanical heterogeneity of the prostate. The analytical formulation showed that increasing the tumor volume and stiffness could significantly increase the impact of the heterogeneous prostate model in the calculated displacement differences compared to the homogeneous model. The parametric approach using a single prostate model indicated up to 4.8?mm of displacement difference at the tumor boundary compared to a homogeneous model. Such differences in the deformation of the prostate could be potentially clinically significant given the voxel size of the ex vivo MR images (0.3? × ?0.3? × ?0.3?mm). However, no significant changes in the registration accuracy were observed using heterogeneous models for the limited number of clinical prostatectomy patients modeled and evaluated in this study.
Calvo, Florent; Yurtsever, Ersin
2009-01-01
The stable structures and melting properties of ion clouds in isotropic octupole traps are investigated using a combination of semi-analytical and numerical models, with a particular emphasis at finite size scaling effects. Small-size clouds are found to be hollow and arranged in shells corresponding approximately to the solutions of the Thomson problem. The shell structure is lost in clusters containing more than a few thousands of ions, the inner parts of the cloud becoming soft and amorphous. While melting is triggered in the core shells, the melting temperature unexpectedly follows the rule expected for three-dimensional dense particles, with a depression scaling linearly with the inverse radius.
Mechanical properties of steel 20 at small deformations
Mytsyk, B. G.; Kost', Ya. P.; Turko, B. I.; Gas'kevich, G. I.
2015-08-01
The elastic hysteresis and residual deflections of samples made of steel 20, which correspond to the model of a thin rigid round plate pinched over the contour, have been investigated. It has been shown that annealing of the samples at 470 and 670 K weakly affects these characteristics, while after complete annealing (1170 K), the aging of steel 20 for three days is accompanied by a decrease in amplitude ? h of the elastic hysteresis by ˜20%. A postulate that there is no elasticity limit of metals, below which residual deformation would be absent, has been confirmed experimentally. It has been shown that, based on the values of ? h , the ultimate strength of metals can be estimated acting on the samples by stresses smaller than the yield stress by an order of magnitude. A giant increase (by a factor of ˜2.5) in ? h has been found after a prolonged (for 2 months) aging of steel 20 after the diffusion of hydrogen from it, which indicates the corresponding decrease in its cyclic longevity.
Red Blood Cell Deformation Under Shear Flow: The Effect of Changing Cell Properties
Forsyth, Alison M.; Wan, Jiandi; Ristenpart, William D.; Stone, Howard A.
2008-11-01
The deformability of red blood cells plays a major role in the pathology of several diseases, including malaria, sickle cell anemia and spherocytosis. Moreover, deformations are believed to trigger the release of adenosine triphosphate, which helps regulate vascular tone and is consequently an important factor in various vascular diseases. Here we investigate single-cell viscoelastic responses to increased shear stress in poly(dimethylsiloxane) channels with a single constriction 2-4 times larger than a typical erythrocyte. These channels mimic arteriole-sized vessels, and have the advantage that the cell membrane is not in contact with the channel walls which have vastly different mechanical and material properties than living tissue. High-speed video and image analysis were used to quantify the trajectories and deformations of cells exposed to varied doses of diamide, a chemical known to ``rigidify'' erythrocytes. Our results show that (i) deformation is proportional to shear rate and (ii) the deformability of diamide-treated cells is greater than that of untreated cells. The latter is an unforeseen result because micropipette aspiration experiments have shown the opposite. We expect that the experimental procedure described here will be useful for characterizing the effect of different therapeutic agents on cellular deformability.
Self-similarity properties of nafionized and filtered water and deformed coherent states
Capolupo, A; Elia, V; Germano, R; Napoli, E; Niccoli, M; Tedeschi, A; Vitiello, G
2013-01-01
By resorting to measurements of physically characterizing observables of water samples perturbed by the presence of Nafion and by iterative filtration processes, we discuss their scale free, self-similar fractal properties. By use of algebraic methods the isomorphism is proved between such self-similarity features and the deformed coherent state formalism.
Analysis of plastic properties of titanium alloys under severe deformation conditions in machining
Directory of Open Access Journals (Sweden)
Alexander I. Khaimovich
2014-10-01
Full Text Available The present paper presents a method of analysis of titanium alloys plastic properties under severe deformation conditions during milling with registration of the cutting force components Fx, Fy, Fz in real time using a special stand. The obtained constitutive relations in the form the Johnson-Cook law for stresses and dependence for a friction coefficient describing the titanium alloy VT9 plastic properties under simulate operating conditions.
Analysis of plastic properties of titanium alloys under severe deformation conditions in machining
Alexander I. Khaimovich; Andrey V. Balaykin
2014-01-01
The present paper presents a method of analysis of titanium alloys plastic properties under severe deformation conditions during milling with registration of the cutting force components Fx, Fy, Fz in real time using a special stand. The obtained constitutive relations in the form the Johnson-Cook law for stresses and dependence for a friction coefficient describing the titanium alloy VT9 plastic properties under simulate operating conditions.
Large-Deformation Properties of Wheat Flour and Gluten Dough
Sliwinski, E.L.
2003-01-01
Keywords: Wheat, gluten protein, bread, puff pastry, flour dough, gluten dough,rheology,uniaxialextension, biaxial extension, fracture.Rheologicaland fracture properties of flour and glutendoughsfrom eight wheat cultivars were studied and related to gluten protein composition and baking performance in bread and puff pastry. For bothuniaxialand biaxial extension flour dough showed a more than proportional increase of stress with increasing strain, a phenomenon called strain hardening. Inuniaxi...
Mechanical properties of explosives under high deformation loading conditions
Tasker, D. G.; Dick, R. D.; Wilson, W. H.
1998-07-01
The mechanical properties of Navy explosive PBXW-128 were measured using a split-Hopkinson pressure bar (SHPB) apparatus at strain rates up to 2.9×104s-1 at room temperature. The true stress-true strain data can be divided into two regions with different moduli, separated by a transition point. Both moduli show significant stiffening with strain rate; above the transition point the modulus increases as the strain rate squared.
Fission fragment formation and fission yields in the model of octupole neutron-proton oscillations
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Yavshits S.
2010-03-01
Full Text Available The fission fragment formation is considered as a result of neck instability in the process of octupole oscillations of neutrons and protons near the scission point. To describe such a phenomenon the potential surface of fissionning nucleus with neck radius about 1 fm was calculated with shell correction approach. The new version of smooth liquid drop part of deformation energy is proposed. The liquid drop part is formulated in a double folding model with n-n, p-p, and n-p Yukawa interaction potential. Fission fragment mass and charge distributions correspond approximately to isoscalar and isovector modes of vibrations and are defined by wave functions of oscillations. The preliminary calculation results have shown a rather good description of main integral fission yield observables.
Microstructure, elastic properties and deformation mechanisms of horn keratin.
Tombolato, Luca; Novitskaya, Ekaterina E; Chen, Po-Yu; Sheppard, Fred A; McKittrick, Joanna
2010-02-01
The structure and mechanical properties of the horns from a desert bighorn sheep, Ovis canadensis, were examined. Horns must be strong and durable as they are subjected to extreme loading impacts, making them superior structural materials. Horns are composed of alpha-keratin, a fibrous, structural protein found in hair, nails, claws and hooves. Horns have a lamellar structure (2-5microm in thickness) stacked in the radial direction with tubules (approximately 40x100microm in diameter) dispersed between the lamellae, extending along the length of the horn in the growth direction. Compression and bending tests were conducted in both rehydrated and ambient dried conditions. The yield strength and elastic modulus are anisotropic and are correlated with the orientation of the tubules. Rehydrated samples showed significant loss of strength and modulus. Microscopy of fractured samples revealed several toughening mechanisms: delamination and ligament bridging in bending and delamination and microbuckling of the lamellae in compression. PMID:19577667
Microstructure, Properties and Atomic Level Strain in Severely Deformed Rare Metal Niobium
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Mart SAARNA
2012-12-01
Full Text Available The mechanical and physical properties relationship from atomic level strain/stress causes dislocation density and electrical conductivity relationship, as well as crystallites deformation and hkl-parameter change in the severely deformed pure refractory rare metal Nb at ambient temperature and during short processing times. The above mentioned issues are discussed in this study. For ultrafine-grained and nanocrystalline microstructure forming in metal the equal-channel angular pressing and hard cyclic viscoplastic deformation were used. The flat deformation and heat treatment at different parameters were conducted as follows. The focused ion beam method was used for micrometric measures samples manufacturied under nanocrystalline microstructure study by transmission electron microscope. The microstructure features of metal were studied under different orientations by X-ray diffraction scattering method, and according to the atomic level strains, dislocation density, hkl-parameters and crystallite sizes were calculated by different computation methods. According to results the evolutions of atomic level strains/stresses, induced by processing features have great influence on the microstructure and advanced properties forming in pure Nb. Due to cumulative strain increase the tensile stress and hardness were increased significantly. In this case the dislocation density of Nb varies from 5.0E+10 cm–2 to 2.0E+11 cm–2. The samples from Nb at maximal atomic level strain in the (110 and (211 directions have the maximal values of hkl-parameters, highest tensile strength and hardness but minimal electrical conductivity. The crystallite size was minimal and relative atomic level strain maximal in (211 orientation of crystal. Next, flat deformation and heat treatment increase the atomic level parameters of severely deformed metal.DOI: http://dx.doi.org/10.5755/j01.ms.18.4.3091
Effect of viscosity of petroleum products on deformation properties of concrete
Directory of Open Access Journals (Sweden)
A.P. Svintsov
2014-11-01
Full Text Available This paper presents the results of studies of the effect of petroleum products, impregnating in concrete, on its deformation properties. Petroleum products, impregnating in concrete and reinforced concrete structures, have a negative impact on their strength and deformation characteristics. The negative impact of petroleum products on concrete and reinforced concrete is associated with changes in the hydration process of cement, as well as changes in the structure of the concrete. Strength and deformation characteristics of concrete change due to hydraulic pressure of petroleum products in the pores exerted on the skeleton of cement stone. In this aspect, the crucial point is the porosity of concrete as a permeability factor for petroleum products. One of the most important factors affecting the physical and mechanical characteristics of oil-impregnated concrete is their viscosity. In this paper, the mathematical description of the change of deformation depending on the relative viscosity of impregnating of petroleum products, the value of the axial load and the concrete class was proposed. The obtained results allow assessing changes in deformation characteristics of load-bearing concrete and reinforced concrete of industrial buildings, where petroleum products are used in the technological processes.
Deformation Properties of Forest Soils in Karelia Affected by "Freeze-Defrost" Cycles
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Ratjkova E. I.
2013-07-01
Full Text Available The impact of “freeze-defrost” cycles on the deformation properties of forest soils has been little studied. The layout of technological schemes of harvesting sites development in off-season periods (spring, fall depends a lot on the formation of ruts when wood harvesting machinery passes. The study of processes occurring in forest soils affected by “freeze-defrost” cycles enables to justify the method of calculating rut depth depending on the number of machinery passes. The compression modulus of deformation, compressibility coefficient and relative compressibility coefficient of clay loam which was collected in the forest of the Republic of Karelia were determined in laboratory conditions. Forest soil samples underwent three “freeze-defrost” cycles. It has been determined clay loam deformation modulus after the first cycle reduces by 16% and after the second and third cycles it reduces by 18% and 25% respectively in relation to the value of deformation modulus before freezing. Compressibility coefficient increases by 18% after the first cycle, it increases by 22% after the second cycle and by 33% after the third one. The decrease of deformation modulus and the increase of clay loam compressibility coefficient are due to changes in the structure of forest soils under the influence of “freeze-defrost” cycles.
A Heisenberg Ferromagnet With Biquadratic and Dipol-octupol Interactions
Ba?k, Z.
1981-08-01
A Heisenberg S - 3/2 ferromagnet with isotropic biquadratic exchange and dipole-octupol coupling is discussed. The conditions for the exact ferromagnetic ground state are derived. The thermodynamical behaviour in the molecular field approximation is discussed. Collective excitation spectra and the 1/z correction to the free energy are found.
Cryogenically cooled octupole ion trap for spectroscopy of biomolecular ions
Energy Technology Data Exchange (ETDEWEB)
Boyarkin, Oleg V., E-mail: oleg.boiarkin@epfl.ch; Kopysov, Vladimir [Laboratoire de Chimie Physique Moléculaire, Ecole Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCPM, Station 6, CH-1015 Lausanne (Switzerland)
2014-03-15
We present here the design of a linear octupole ion trap, suitable for collisional cryogenic cooling and spectroscopy of large ions. The performance of this trap has been assessed using ultraviolet (UV) photofragmentation spectroscopy of protonated dipeptides. At the trap temperature of 6.1 K, the vibrational temperature of the ions reaches 9.1 K, although their estimated translational temperature is ?150 K. This observation suggests that, despite the significant translational heating by radio-frequency electrical field, vibrational cooling of heavy ions in the octupole is at least as efficient as in the 22-pole ion traps previously used in our laboratory. In contrast to the 22-pole traps, excellent radial confinement of ions in the octupole makes it convenient for laser spectroscopy and boosts the dissociation yield of the stored ions to 30%. Overlap of the entire ion cloud by the laser beam in the octupole also allows for efficient UV depletion spectroscopy of ion–He clusters. The measured electronic spectra of the dipeptides and the clusters differ drastically, complicating a use of UV tagging spectroscopy for structural determination of large species.
Measurement of tune spread in the Tevatron versus octupole strength
International Nuclear Information System (INIS)
A experiment was performed in the Tevatron to measure the tune spread versus octupole strength. The experiment is sensitive to the relationship between octupole strength and current in the T:OZF circuit and to the octupole (and other non-linear focusing fields) in the Tevatron. The major motivation for the experiment was to determine the value of octupole excitation that minimizes the tune spread: this value is an estimate of the value required to obtain ''zero'' total octupole excitation in the extraction process. The experiment was performed using the strip-line kickers at A17 and the resonant Schottky pickups. The horizontal proton kicker was excited with a sine-wave from a vector signal analyzer (HP-89440A) and the horizontal proton signal was received. The gating circuitry normally used to select proton or antiproton bunches was by-passed. The response function was measured and recorded on a floppy disk. Measurements were initially made with a 200 Hz span (0.250 Hz frequency bins) and later with a 100 Hz span (0.125 Hz frequency bins). The data was all obtained at flattop (800 GeV) with Q39S and Q39C set to correct the 1/2 integer stop band and QXR (the extraction regulation system) turned off. No attempt was made to examine sensitivity to closed orbit, chromaticity, or any other machine parameters other than the zero harmonic octupoles. The tune varied slightly (presumably because of feed-down effects from the octupoles), but was approximately constant at 19.472 (only the fractional part was measured). The beam emittance was not measured because the flying wires were not working when these data were taken. The analysis of the data was accomplished by replotting the data from the floppy disk. The peak amplitude and the full width at 25% of the peak height were measured. Figures 1-7 show some of the data that was obtained. The vertical scales in figures 1-7 are adjusted so that the data span 80% of the full height of the screen. The hardware requires the markers to be measured points, so the width measured is not exactly at 25% of full height
International Nuclear Information System (INIS)
Highlights: ? We fabricated a 310 type ODS austenitic steel by the process of MA and HIP. ? Plastic deformations, including forging and hot rolling, were applied to samples. ? Fine Y-Ti-O particles dispersed in a relatively uniform way after forging. ? Ductility increased greatly after deformations, while strength decreased slightly. - Abstract: ODS-310 austenitic steel (Fe–25Cr–20Ni–0.35Y2O3–0.5Ti) was fabricated by the process of mechanical alloying and hot isostatic pressing. Plastic deformations, including forging and hot rolling, were applied to the as-hipped samples to improve the ductility. Microstructural evolutions in samples under different fabrication conditions were characterized by TEM. Tensile properties were tested at 23 °C and 700 °C. Dispersed oxide particles with sizes between 10 nm and 50 nm were characterized to be rich in Y–Ti–O. UTS and elongation of the as-hipped sample were 904 MPa and 11% respectively at 23 °C. Elongation increased two times after plastic deformations while there was only slight decrease in strength properties.
Energy Technology Data Exchange (ETDEWEB)
Wang Man [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 10083 (China); Zhou Zhangjian, E-mail: zhouzhj@mater.ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 10083 (China); Sun Hongying; Hu Helong; Li Shaofu [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 10083 (China)
2012-11-15
Highlights: Black-Right-Pointing-Pointer We fabricated a 310 type ODS austenitic steel by the process of MA and HIP. Black-Right-Pointing-Pointer Plastic deformations, including forging and hot rolling, were applied to samples. Black-Right-Pointing-Pointer Fine Y-Ti-O particles dispersed in a relatively uniform way after forging. Black-Right-Pointing-Pointer Ductility increased greatly after deformations, while strength decreased slightly. - Abstract: ODS-310 austenitic steel (Fe-25Cr-20Ni-0.35Y{sub 2}O{sub 3}-0.5Ti) was fabricated by the process of mechanical alloying and hot isostatic pressing. Plastic deformations, including forging and hot rolling, were applied to the as-hipped samples to improve the ductility. Microstructural evolutions in samples under different fabrication conditions were characterized by TEM. Tensile properties were tested at 23 Degree-Sign C and 700 Degree-Sign C. Dispersed oxide particles with sizes between 10 nm and 50 nm were characterized to be rich in Y-Ti-O. UTS and elongation of the as-hipped sample were 904 MPa and 11% respectively at 23 Degree-Sign C. Elongation increased two times after plastic deformations while there was only slight decrease in strength properties.
International Nuclear Information System (INIS)
Knowledge of the complex interacting processes of dilatancy and healing is of vital interest for a characterization of the long term behaviour of a repository, independently from rock type. Constitutive models are needed to describe the development of the EDZ during inelastic closure of excavations in geological formations. They are typically expressed in terms of elastic constants, temperature, stress invariants, humidity, and empirical fitting parameters, assuming, at least, isotropic conditions. However, especially argillaceous rocks are inherently anisotropic. Depending on progressive compaction and a transformation of the originally deposited clay into an over-consolidated clay, clay stone or shale, the rocks become progressively foliated parallel to the bedding due to the sheet structure of the rock forming clay minerals. Although such planar discontinuities can act as preferential flow paths and play an important role on the initiation of inelastic deformation their impact on transport properties and deformation has been largely overlooked. While elastic deformation is usually more or less isotropic, initiation of inelastic deformation and the relative dilatation are clearly a function of bedding plane properties, the spatial orientation and stress geometry. These overlapping effects are particularly important during rock stress redistribution in the EDZ. Amongst others, this laboratory study will focus on the impact of mechanical properties of argillaceous rocks on the transport properties with respect to the bedding plane. The points of interest are subdivided in the following tasks: (1) Anisotropy of mechanical and transport properties referred to the bedding plane (2) Onset of dilatancy and its evolution (healing and damage) (3) Mechanical strength of the bedding plane direct shear strength testing. (authors)
Energy Technology Data Exchange (ETDEWEB)
Popp, T.; Salzer, K. [Institut fur Gebirgsmechanik GmbH, Leipzig (Germany)
2005-07-01
Knowledge of the complex interacting processes of dilatancy and healing is of vital interest for a characterization of the long term behaviour of a repository, independently from rock type. Constitutive models are needed to describe the development of the EDZ during inelastic closure of excavations in geological formations. They are typically expressed in terms of elastic constants, temperature, stress invariants, humidity, and empirical fitting parameters, assuming, at least, isotropic conditions. However, especially argillaceous rocks are inherently anisotropic. Depending on progressive compaction and a transformation of the originally deposited clay into an over-consolidated clay, clay stone or shale, the rocks become progressively foliated parallel to the bedding due to the sheet structure of the rock forming clay minerals. Although such planar discontinuities can act as preferential flow paths and play an important role on the initiation of inelastic deformation their impact on transport properties and deformation has been largely overlooked. While elastic deformation is usually more or less isotropic, initiation of inelastic deformation and the relative dilatation are clearly a function of bedding plane properties, the spatial orientation and stress geometry. These overlapping effects are particularly important during rock stress redistribution in the EDZ. Amongst others, this laboratory study will focus on the impact of mechanical properties of argillaceous rocks on the transport properties with respect to the bedding plane. The points of interest are subdivided in the following tasks: (1) Anisotropy of mechanical and transport properties referred to the bedding plane (2) Onset of dilatancy and its evolution (healing and damage) (3) Mechanical strength of the bedding plane direct shear strength testing. (authors)
Maharaj, Dave; Bhushan, Bharat
2014-01-01
Nanoscale research of bulk solid surfaces, thin films and micro- and nano-objects has shown that mechanical properties are enhanced at smaller scales. Experimental studies that directly compare local with global deformation are lacking. In this research, spherical Au nanoparticles, 500 nm in diameter and 100 nm thick Au films were selected. Nanoindentation (local deformation) and compression tests (global deformation) were performed with a nanoindenter using a sharp Berkovich tip and a flat p...
Kitagawa, H.; Kurata, A.; Araki, H.; Morito, S.; Tanabe, E.
2010-09-01
The effects of deformation temperature on texture and thermoelectric properties of p-type Bi0.5Sb1.5Te3 sintered materials were investigated. The sintered materials were prepared by mechanical alloying and hot-press sintering. The hot-press deformation was performed at 723 K and 823 K by applying mechanical pressure in a graphite die. Then, the materials were extruded in the direction opposite to the direction of applied pressure. X-ray diffraction and electron backscattered diffraction patterns showed that the hexagonal c-plane tended to align along the extruded direction when the samples were deformed at high temperatures. The thermoelectric power factor was increased by high-temperature hot-press deformation because of the low electrical resistivity that originated from the c-plane orientation.
Wang, Man; Zhou, Zhangjian; Sun, Hongying; Hu, Helong; Li, Shaofu
2012-11-01
ODS-310 austenitic steel (Fe-25Cr-20Ni-0.35Y2O3-0.5Ti) was fabricated by the process of mechanical alloying and hot isostatic pressing. Plastic deformations, including forging and hot rolling, were applied to the as-hipped samples to improve the ductility. Microstructural evolutions in samples under different fabrication conditions were characterized by TEM. Tensile properties were tested at 23 °C and 700 °C. Dispersed oxide particles with sizes between 10 nm and 50 nm were characterized to be rich in Y-Ti-O. UTS and elongation of the as-hipped sample were 904 MPa and 11% respectively at 23 °C. Elongation increased two times after plastic deformations while there was only slight decrease in strength properties.
DEFF Research Database (Denmark)
Fugl, Andreas Rune; Jordt, Andreas; Petersen, Henrik Gordon; Willatzen, Morten; Koch, Reinhard
2012-01-01
In this paper we consider the problem of estimating 6D pose and material properties of a deformable object grasped by a robot grip- per. To estimate the parameters we minimize an error function incorpo- rating visual and physical correctness. Through simulated and real-world experiments we demonstrate that we are able to ?nd realistic 6D poses and elasticity parameters like Young’s modulus. This makes it possible to perform subsequent manipulation tasks, where accurate modelling of the elastic b...
Effect of droplet-matrix interactions on large deformation properties of emulsion-filled gels
Sala, G.; Aken, G.A., van; Cohen Stuart, M.A.; van de Velde, F.
2007-01-01
The aim of this work was to identify the effect of droplet¿matrix interactions on the large deformation properties of emulsion-filled gels. A study was carried out on the behavior in compression of gelatin, whey protein isolate (WPI) and ¿-carrageenan gels containing emulsions stabilized by different emulsifying agents (WPI, WPI aggregates, lysozyme, polyoxyethylenesorbitan monolaurate [Tween 20]) to control droplet¿matrix interactions. For gelatin gels, emulsions stabilized with WPI and lyso...
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.
Microstructure and Local Mechanical Properties of Cu-Co Alloys after Severe Plastic Deformation.
Czech Academy of Sciences Publication Activity Database
Buršík, Ji?í; Buršíková, V.; Svoboda, Milan; Král, Petr; Dvo?ák, Ji?í; Skleni?ka, Václav
Zurich : Trans Tech Publications, 2014 - (Pešek, L.; Zubko, P.), s. 100-103 ISBN 978-3-03785-876-9. ISSN 1013-9826. - (Key Engineering Materials. 586). [LMP 2012 International Conference on Local Mechanical Properties /9./. Levo?a (SK), 07.11.2012-09.11.2012] R&D Projects: GA ?R(CZ) GAP108/11/2260 Institutional support: RVO:68081723 Keywords : severe plastic deformation * electron microscopy * EBSD Subject RIV: JG - Metallurgy
Semiclassical analysis of the lowest-order multipole deformations of simple metal clusters
Pashkevich, V V; Brack, M; Unzhakova, A V
2002-01-01
We use a perturbative semiclassical trace formula to calculate the three lowest-order multipole (quadrupole $\\eps_2$, octupole $\\eps_3$, and hexadecapole $\\eps_4$) deformations of simple metal clusters with $90 \\le N \\le 550$ atoms in their ground states. The self-consistent mean field of the valence electrons is modeled by an axially deformed cavity and the oscillating part of the total energy is calculated semiclassically using the shortest periodic orbits. The average energy is obtained from a liquid-drop model adjusted to the empirical bulk and surface properties of the sodium metal. We obtain good qualitative agreement with the results of quantum-mechanical calculations using Strutinsky's shell-correction method.
Crystallization of Ca+ ions in a linear rf octupole ion trap
International Nuclear Information System (INIS)
A laser-cooling experiment with Ca+ ions trapped in a linear rf octupole ion trap is presented. The phase transition of the laser-cooled Ca+ ions from the cloud to the crystal state is observed by an abrupt dip of the laser-induced fluorescence spectrum and indicates that mK temperatures are obtained. We have also performed molecular dynamics simulations under various conditions to confirm this property by deducing axially symmetric structures of Coulomb crystals and by evaluating the translational temperatures of the laser-cooled ions. The simulation results show that for small numbers of ions novel ring-shaped crystals are produced. As the number of ions is increased, cylindrical layers in the ring crystal are sequentially formed. For more than 100 ions, also hexagonal and spiral structures emerge in parts of the large-size ion crystal, which has a length on the order of millimeters for the present geometrical arrangement and voltages. An advantage of the linear rf octupole trap is its large almost-field-free region in the middle of the trap, where the micromotion amplitude is small for trapped ions. These results demonstrate that such a multipole trap has attractive features for quantum computing and ultracold ion-atom collision studies
Analysis on the Soil Dynamic Properties and Accumulated Deformation under the Rail Traffic Loads
Directory of Open Access Journals (Sweden)
Liwei Shen
2014-03-01
Full Text Available The dynamic behaviors of soil under the rail traffic load are obviously different from that under the other loads such as earthquake load and wave load. So the dynamic properties of soil under the rail traffic must be studied in specially. In this paper, the existing studies are summarized and analyzed in several aspects such as the dynamic properties of soil by testing, the constitutive model with considering the cyclic principal stress rotation, the calculated method for accumulated deformation of soil and the model test. Some shortages in existing studies are analyzed and some scientific questions which are worthy to be researched further are mentioned.
Conflicting results for the deformation properties of forsterite, Mg2SiO4
International Nuclear Information System (INIS)
Deformation properties of forsterite have been deduced simultaneously from X-ray diffraction data affected by extinction in Bonn-Pittsburgh (B), and in Groningen (G). For the G crystals, GI and GII, extinction is anisotropic and considerably larger than for crystal B. Measurements were made with Mo radiation for B, and with Mo and Ag radiation for GI and GII. As the Becker and Coppens extinction model is not exact, the deformation properties had to be filtered from the data with refinement models. The flexible B model [?'s and populations for single exponential functions (SEF's) refined for l=0-4] and the more rigid G model (SEF's populations refined for l=0-3 and ? for l=0; further ?'s and n's fixed at standard values) yield different results. Refinement of ? makes the majority of the SEF's notably diffuse, presumably due to correlation with incorrect extinction corrections. The order of the deformation potentials at the Mg(1) and Mg(2) sites is reversed for B and G. Maxima on the Si-O bonds, which are polarized towards O, are smaller for G (0.20-0.25 e A-3) than for B (0.25-0.45 e A-3). Although each of the two sets of deformation properties looks acceptable by itself, the present comparison shows that neither of them may be sufficiently close to the truth. The diffraction data are available on request from the Electron Density Data Bank (Professor H. Burzlaff, Institut fuer Angewandte Physik, Bismarckstrasse 10, D-8520 Erlangen, Federal Republic of Germany). Details of the measurements are described in the paper. (orig.)
Indian Academy of Sciences (India)
Sudhanshu Choudhary; S Qureshi
2012-10-01
We investigate electron transport properties in a deformed (8, 0) silicon carbide nanotube by applying self consistent non-equilibrium Green’s function formalism in combination with the density-functional theory to a two-probe molecular junction constructed from deformed nanotube. The results suggest significant reduction in threshold voltage in the case of both radially compressed and axially elongated (8, 0) SiCNTs, a large difference in current–voltage characteristics was observed. Analysis of frontier molecular orbitals (FMO) and transmission spectrum show bandgap reduction in deformed nanotubes. Deformation introduces electronic states near the Fermi level, enhancing the conduction properties of (8, 0) SiCNT. The FMOs and the orbitals corresponding to peaks in () around Fermi level obviously has some major contributions from the deformed site. However, localization of the electronic state near the Fermi level is weak in (8, 0) SiCNT, possibly because of its large bandgap.
International Nuclear Information System (INIS)
Thermal problems that are directly related to the lifetime of an electronic device are becoming increasingly important owing to the miniaturization of electronic devices. To solve thermal problems, it is essential to study thermal stability through thermal diffusion and insulation. A honeycomb sandwich plate has anisotropic thermal conductivity. To analyze the thermal deformation and temperature distribution of a system that employs a honeycomb sandwich plate, the thermal and elastic properties need to be determined. In this study, the thermal and elastic properties of a honeycomb sandwich plate, such as thermal conductivity, coefficient of thermal expansion, elastic modulus, Poisson's ratio, and shear modulus, are predicted. The properties of a honeycomb sandwich plate vary according to the hexagon size, thickness, and material properties
Influence of materials properties on stress and deformation states of a prestressed concrete vessel
International Nuclear Information System (INIS)
The influence of changes in some material parameters on relevant operational states is studied for a vessel with a concrete liner temperature of 700C. The results are given for the following material properties: thermal conductivity, thermal expansion coefficient, young's modulus, temperature dependency of the creep, steel tendon relaxation. The influence of changes in the initial strain due to deformation of the vessel also gets a mention. As the behaviour at 700C does not deviate significantly from the behaviour described in the extensive studies on a vessel of 500C, the calculations in this paper are essentially confined to two final operational states which illustrate the influence of the material parameters on the strains and deformations which are of interest for the layout of the vessel. (orig./AK)
Structure and properties of Fe-36% Ni alloy after heavy shear deformation
International Nuclear Information System (INIS)
A study was made into the influence of large shear strain by pressing on structure, mechanical and thermal properties of the Fe-36% Ni invar. The first pressing pass (70% reduction) is shown to result in formation of strip structure. An increase of the number of passes with changing shear deformation direction for reverse one at every even pressing p[ass promotes strip structure transformation into fragmented one. Yield strength of the alloy increases from 300 to 650 N/mm2 after the first pass. After 12 passes at attains the value of 800 N/mm2 due to strain hardening. A linear thermal expansion coefficient varies nonmonotonously with deformation, and after 12 passes preserves a permissible value. 17 refs., 10 figs
Optimisation by plastic deformation of structural and mechanical uranium alloys properties
International Nuclear Information System (INIS)
Structural and mechanical properties evolution of rich and poor uranium alloys are investigated. Good usual properties are obtained with few metallic additions with a limited effect giving a fine and isotrope grain structure. Amelioration is observed with heat treatment from ? and ? phases high temperature range. However, dynamic recrystallisation, related to hot working, is the better phenomena to maximize the usual mechanical and structural properties. So high temperature behaviour of rich and poor uranium alloys in ?, ? and ? crystalline structure is studied: - dynamic recrystallisation phenomena begins only in ?, and ? phases high temperature range; - high strength and brittle ? phase shows a very large ductility above 700 deg C. Recrystallisation is a thermal actived phenomena localised at grain boundary, dependant with alloys concentration and crystalline structure. ? phase activation energy and deformation rate for dynamic recrystallisation beginning are most important, than ? and ? phases in relation with quadratic structure complexity. Both temperature and deformation rate are the main dynamic recrystallisation factors. Optimal usual mechanical and structural properties obtained by hot working (forging, milling) are sensible to hydrogen embrittlement
Designing electronic properties of two-dimensional crystals through optimization of deformations
International Nuclear Information System (INIS)
One of the enticing features common to most of the two-dimensional (2D) electronic systems that, in the wake of (and in parallel with) graphene, are currently at the forefront of materials science research is the ability to easily introduce a combination of planar deformations and bending in the system. Since the electronic properties are ultimately determined by the details of atomic orbital overlap, such mechanical manipulations translate into modified (or, at least, perturbed) electronic properties. Here, we present a general-purpose optimization framework for tailoring physical properties of 2D electronic systems by manipulating the state of local strain, allowing a one-step route from their design to experimental implementation. A definite example, chosen for its relevance in light of current experiments in graphene nanostructures, is the optimization of the experimental parameters that generate a prescribed spatial profile of pseudomagnetic fields (PMFs) in graphene. But the method is general enough to accommodate a multitude of possible experimental parameters and conditions whereby deformations can be imparted to the graphene lattice, and complies, by design, with graphene's elastic equilibrium and elastic compatibility constraints. As a result, it efficiently answers the inverse problem of determining the optimal values of a set of external or control parameters (such as substrate topography, sample shape, load distribution, etc) that result in a graphene deformation whose associated PMF profile best matches a prescribed target. The ability to address this inverse problem in an expedited way is one key step for practical implementations of the concept of 2D systems with electronic properties strain-engineered to order. The general-purpose nature of this calculation strategy means that it can be easily applied to the optimization of other relevant physical quantities which directly depend on the local strain field, not just in graphene but in other 2D electronic membranes. (paper)
Tests of octupole band structures using proton scattering and gamma-ray spectroscopy
International Nuclear Information System (INIS)
In many even-even nuclei, bands of negative parity states have been interpreted as open-quotes octupole bandsclose quotes, which are sequences of vibrational or rotational excitations coupled to a low energy octupole phonon. Careful experimental examination of these structures is of interest because octupole phonons are generally considered to be unstable at high angular momentum. Results from experimental studies of octupole band structures in three nuclei are presented. Two of these nuclei, 144,146Nd, have been studied via inelastic scattering of 35 MeV protons. The third nucleus, 74Se, has been examined using the techniques of high spin gamma-ray spectroscopy
Periodic-Orbit Bifurcation and Shell Structure in Reflection-Asymmetric Deformed Cavity
Sugita, A.; Arita, K; Matsuyanagi, K
1997-01-01
Shell structure of the single-particle spectrum for reflection-asymmetric deformed cavity is investigated. Remarkable shell structure emerges for certain combinations of quadrupole and octupole deformations. Semiclassical periodic-orbit analysis indicates that bifurcation of equatorial orbits plays an important role in the formation of this new shell structure.
Deformation properties of highly plastic fissured Palaeogene clay - Lack of stress memory?
DEFF Research Database (Denmark)
KrogsbØll, Anette; Hededal, Ole
2012-01-01
The geological preconsolidation of the Palaeogene clays in Denmark is estimated to 5-8 MPa or more, whereas laboratory and field experiences indicate values between 100 and 3000 kPa. Presumably, the high plasticity clay loses its memory of earlier preloads due to swelling, or as an effect of fissuring or debonding. Based on a large amount of high quality tests on Palaeogene clay partly encountered at Fehmarn Belt the typical deformational behaviour during unloading and swelling is discussed and evaluated with focus on stress states. K0-OCR relations are established and the relations are evaluated based on the degree of debonding caused by natural processes insitu as compared to processes induced during severe loading and unloading in laboratory. A long term oedometer test on Lillebælt Clay with a series of loading and unloading cycles was carried out. The test results are used to evaluate deformation properties, and to help explain the large primary and secondary swelling indices measured in Palaeogene claysand how they are related to preconsolidation stress. It is proven that the Palaeogene clay tends to “forget” the preconsolidation stress and the consequence is that OCR is not always a suitable parameter to estimate deformation and strength parameters from, unless additional information on structure of the clay is included. This is not solved yet.
Energy Technology Data Exchange (ETDEWEB)
Langdon, T. G.
2008-07-01
The processing of polycrystalline metals through the application of severe plastic deformation is attracting much attention because of the potential for achieving significant grain refinement to the submicrometer or nanometer level. This paper reviews the principles of this type of processing with emphasis on two different techniques: Equal-Channel Angular Pressing and High-Pressure Torsion. Exceptional properties may be achieved from these processes including high strength at ambient temperatures and a rapid superplastic forming capability at elevated temperatures. Some examples are presented demonstrating the potential use of this type of processing. (Author) 53 refs.
International Nuclear Information System (INIS)
A study is made into the influence of plastic deformation by torsion under hydrostatic pressure on microstructure phase composition and magnetic hysteresis in cast alloy Pr20Fe73.5B5Cu1.5. It is shown that heavy deformation results in essential refinement if basic Pr2Fe14B phase and subsequent formation of nonequilibrium and amorphous phases. The structural changes are the reasons for the external dependence of coercive force Hc on deformation degree. The annealing of heavily deformed specimens is accompanied by a sharp decrease of coercive force up to values exceeding 1600 kA/m. It is concluded that heavy deformation along with rapid quenching is a promising method to improve crystal structure and magnetic properties of R2Fe14B intermetallic alloys
Effects of deformation on the electronic properties of B-C-N nanotubes
Energy Technology Data Exchange (ETDEWEB)
Azevedo, S., E-mail: sazevedo@fisica.ufpb.br [Departamento de Fisica, Universidade Federal da Paraiba, Caixa Postal 5008, 58059-900 Joao Pessoa-PB (Brazil); Rosas, A. [Departamento de Fisica, Universidade Federal da Paraiba, Caixa Postal 5008, 58059-900 Joao Pessoa-PB (Brazil); Machado, M. [Departamento de Fisica, Universidade Federal de Pelotas, Caixa Postal 354, 96010-900 Pelotas-RS (Brazil); Kaschny, J.R. [Instituto Federal da Bahia-Campus Vitoria da Conquista, Av. Amazonas 3150, 45030-220 Vitoria da Conquista-BA (Brazil); Chacham, H. [Departamento de Fisica, ICEX, Universidade Federal de Minas Gerais, Caixa Postal 702, 30123-970 Belo Horizonte-MG (Brazil)
2013-01-15
We apply first-principles methods, using density functional theory, to investigate the effects of flattening deformation on the electronic properties of BC{sub 2}N and C-doped BNNTs. Four different types of BC{sub 2}N structures are considered. Two of them are semiconductors, and the radial compression produces a significant reduction of the energy band gap. The other two types of structures are metallic, and the effect of radial compression is quite distinct. For one of them it is found the opening of a small band gap, and for the other one no changes are observed. For C-doped tubes, it is also found that the electronic properties undergo significant modifications when subjected to radial compression. - Graphical Abstract: We apply first-principles methods, using density functional theory, to investigate the effects of flattening deformation on the electronic properties of BC{sub 2}N and C-doped BNNTs. Four different types of BC{sub 2}N structures are considered. Two of them are semiconductors, and the radial compression produces a significant reduction of the energy band gap. The other two types of structures are metallic, and the effect of radial compression is quite distinct. For one of them it is found the opening of a small band gap, and for the other one no changes are observed. For C-doped tubes, it is also found that the electronic properties undergo significant modifications when subjected to radial compression. Highlights: Black-Right-Pointing-Pointer We investigated electronic properties of flattened BC{sub 2}N nanotubes. Black-Right-Pointing-Pointer The electronic states depend strongly on compression. Black-Right-Pointing-Pointer It is studied flattened BN nanotubes doped with a carbon atom. Black-Right-Pointing-Pointer The flattened C-doped structures, presents a significant reduction of the gap.
Ambipolar electric fields and turbulence studies in the Wisconsin levitated toroidal octupole
International Nuclear Information System (INIS)
Detailed studies of hot ion plasmas (T/sub i/ > T/sub e/) in the poloidal field octupole show that the ambipolar electric field which is perpendicular to the flux surfaces is well explained by the observed properties of the microturbulence structures in the plasma. The turbulence structure has been measured by correlation techniques which are carefully described. In these experiments, signals were studied which are aperiodic in time and space, short lived compared to the decay times of the bulk plasma parameters, short ranged compared to the machine size, and are therefore classified as microturbulence structures. The resulting spatial and temporal correlation functions (CFs) are well fitted to a Gaussian function and the associated correlation lengths or times are the half width at half maximum of the CFs. The correlation length is measured to be the ion gyro radius for the hot hydrogen plasma and somewhat less for the helium plasma
International Nuclear Information System (INIS)
Polypropylene/montmorillonite nano composite was prepared by melt intercalation method using a twin-screw extruder with starve feeding system in this paper. The effects of compatibilizer, extruder rotor speed and feeding rate on properties of nano composite were investigated. Structure, tensile, and impact properties and deformation mechanism of the compounds were studied. For investigation of structure and deformation mechanisms, X-ray diffraction (XRD) and transmission optical microscopy (TOM) techniques were utilized, respectively. The results illustrate that introduction of the compatibilizer and also variation of the processing conditions affect structure and mechanical properties of nano composite.
Kang, ChanKyu; Overfelt, Ruel A.; Roh, Changhyun
2013-01-01
Understanding the mechanical properties of optically transparent polydimethylsiloxane (PDMS) microchannels was essential to the design of polymer-based microdevices. In this experiment, PDMS microchannels were filled with a 100??M solution of rhodamine 6G dye at very low Reynolds numbers (?10?3). The deformation of PDMS microchannels created by pressure-driven flow was investigated by fluorescence microscopy and quantified the deformation by the linear relationship between dye layer thickness...
Diamond, Larryn W.; Tarantola, Alexandre
2015-05-01
A well developed theoretical framework is available in which paleofluid properties, such as chemical composition and density, can be reconstructed from fluid inclusions in minerals that have undergone no ductile deformation. The present study extends this framework to encompass fluid inclusions hosted by quartz that has undergone weak ductile deformation following fluid entrapment. Recent experiments have shown that such deformation causes inclusions to become dismembered into clusters of irregularly shaped relict inclusions surrounded by planar arrays of tiny, new-formed (neonate) inclusions. Comparison of the experimental samples with a naturally sheared quartz vein from Grimsel Pass, Aar Massif, Central Alps, Switzerland, reveals striking similarities. This strong concordance justifies applying the experimentally derived rules of fluid inclusion behaviour to nature. Thus, planar arrays of dismembered inclusions defining cleavage planes in quartz may be taken as diagnostic of small amounts of intracrystalline strain. Deformed inclusions preserve their pre-deformation concentration ratios of gases to electrolytes, but their H2O contents typically have changed. Morphologically intact inclusions, in contrast, preserve the pre-deformation composition and density of their originally trapped fluid. The orientation of the maximum principal compressive stress (?1) at the time of shear deformation can be derived from the pole to the cleavage plane within which the dismembered inclusions are aligned. Finally, the density of neonate inclusions is commensurate with the pressure value of ?1 at the temperature and time of deformation. This last rule offers a means to estimate magnitudes of shear stresses from fluid inclusion studies. Application of this new paleopiezometer approach to the Grimsel vein yields a differential stress (?1-?3) of ˜ 300 MPa at 390 ± 30 °C during late Miocene NNW-SSE orogenic shortening and regional uplift of the Aar Massif. This differential stress resulted in strain-hardening of the quartz at very low total strain (< 5%) while nearby shear zones were accommodating significant displacements. Further implementation of these experimentally derived rules should provide new insight into processes of fluid-rock interaction in the ductile regime within the Earth's crust.
Octupole Ordering Model for the Phase IV of CexLa1-xB6
Kubo, K; Kubo, Katsunori; Kuramoto, Yoshio
2003-01-01
An octupole ordering model is studied by the mean field theory, and its relevance to the phase IV of CexLa1-xB6 is discussed. The observed lattice distortion along the [111] direction is interpreted in terms of the \\Gamma_{5g}-type ferro-quadrupole moment induced by an antiferro-octupole ordered state with \\Gamma_{5u} symmetry. The octupole model also accounts for the cusp in the magnetization as in the N\\'{e}el transition, and the softening of the elastic constant C_{44} below the ordering temperature. However, the internal magnetic field due to the octupole moment is smaller than the observed one by an order of magnitude. Also discussed is the possibility of a pressure induced antiferromagnetic moment in the octupole-ordered state.
Design of an electrostatic octupole for micro-beam deflection
International Nuclear Information System (INIS)
In electrostatic deflection of focused ion and electron beams, a homogeneous field should be maintained within the deflector to reduce aberrations. The geometrical and voltage conditions are investigated to produce an electric field as homogeneous as possible within an octupole deflector. If the eight electrodes are equally shaped into a triangular cross section and are directed as one edge of each electrode with an angle of 3600/8 showing to the center of the device, then the adjacent electrode faces form parallel plate capacitors and the resulting field is the best fit to the ideal cosine potential distribution at the inner circle of the electrodes. (author)
High-spin octupole yrast levels in 216Rn86
International Nuclear Information System (INIS)
The yrast level structure of 216Rn has been studied using in-beam spectroscopy ?-?-? coincidence techniques through the 208Pb(18O, 2?2n) reaction in the 91-93 MeV energy range, using the 8? GASP-ISIS spectrometer at Legnaro. The level scheme of 216Rn resulting from this study shows alternating parity bands only above a certain excitation energy. From this result, the lightest nucleus showing evidence of octupole collectivity at low spins is still 216Fr, thereby defining the lowest-mass corner for this kind of phenomenon as N?129 and Z?87
Kastl, Lena; Budde, Björn; Isbach, Michael; Rommel, Christina; Kemper, Björn; Schnekenburger, Jürgen
2015-05-01
There is a growing interest in cell biology and clinical diagnostics in label-free, optical techniques as the interaction with the sample is minimized and substances like dyes or fixatives do not affect the investigated cells. Such techniques include digital holographic microscopy (DHM) and the optical stretching by fiber optical two beam traps. DHM enables quantitative phase contrast imaging and thereby the determination of the cellular refractive index, dry mass and the volume, whereas optical cell stretching reveals the deformability of cells. Since optical stretching strongly depends on the optical properties and the shape of the investigated material we combined the usage of fiber optical stretching and DHM for the characterization of pancreatic tumor cells. The risk of tumors is their potential to metastasize, spread through the bloodstream and build distal tumors/metastases. The grade of dedifferentiation in which the cells lose their cell type specific properties is a measure for this metastatic potential. The less differentiated the cells are, the higher is their risk to metastasize. Our results demonstrate that pancreatic tumor cells, which are from the same tumor but vary in their grade of differentiation, show significant differences in their deformability. The retrieved data show that differentiated cells have a higher stiffness than less differentiated cells of the same tumor. Even cells that differ only in the expression of a single tumor suppressor gene which is responsible for cell-cell adhesions can be distinguished by their mechanical properties. Additionally, results from DHM measurements yield that the refractive index shows only few variations, indicating that it does not significantly influence optical cell stretching. The obtained results show a promising new approach for the phenotyping of different cell types, especially in tumor cell characterization and cancer diagnostics.
Effect of mechanical deformation on the electrical properties of organic single crystals
Reyes-Martinez, Marcos; Crosby, Alfred; Briseno, Alejandro
2014-03-01
Despite efforts in the flexible electronics field, relatively little research quantified the effects of mechanical strain on the electrical properties of organic single crystals (OSCs) and their device performance in deformed geometries. Single crystals of organic semiconductors are ideal systems for the elucidation of these effects without having to account for imperfections, grain boundaries and other defects. The aim of this presentation is to bring new understanding of the effects of mechanical strain in charge transport phenomena on OSCs. First, the existence of a piezoresistive effect in rubrene crystals is demonstrated and experimentally quantified by the application of in-plane strain along its [010] axis. A piezoresistive coefficient approximately 50 is determined. Second, the effect of local mechanical deformation on the conductive channel is investigated in rubrene single-crystal field-effect transistors. A wrinkling instability is used as a technique to apply local strains of different magnitudes to the conducting channel of field-effect transistors. All devices maintain excellent transistor behavior, and small, reversible changes in performance are observed during wrinkling. This work provides useful knowledge for the effective application of organic semiconductors in strain intensive applications such as pressure sensors, electronic skins and strained-channel organic transistors.
Transient deformation properties of Zircaloy for LOCA simulation. Final report, Volume 2
Energy Technology Data Exchange (ETDEWEB)
Hann, C.R.; Mohr, C.L.; Busness, K.M.; Olson, N.J.; Reich, F.R.; Stewart, K.B.
1978-03-01
The creep/creep rupture anisotropic properties of Zircaloy were determined and compared by analytical techniques with ramp-pressure and ramp-temperature test results. Tests were performed over the temperature range of 600/sup 0/F (589/sup 0/K) to 2200/sup 0/F (1477/sup 0/K), with the emphasis on the 800/sup 0/F (700/sup 0/K) to 2000/sup 0/F (1366/sup 0/K) temperature levels in low pressure air (6.5 x 10/sup -5/ atm) and in a 1 atm mixture of 20 percent oxygen, 80 percent argon. Stress levels of 60 to 95 percent of the ultimate tensile stress were used for the majority of the tests at each of the temperature levels tested, with selected tests performed as low as 30 percent of the ultimate tensile stress. Biaxial and uniaxial testing modes were used to evaluate the anisotropic deformation behavior. The combination of test results and predictive-analysis techniques developed as part of this program make it possible to predict the transient deformation of reactor fuel cladding during simulated LOCA conditions. Results include creep/creep rupture strain numerical constitutive relationships out to 120 seconds, computer codes and ramp test data.
Transient deformation properties of Zircaloy for LOCA simulation. Volume 2. Final report
Energy Technology Data Exchange (ETDEWEB)
Hann, C.R.; Mohr, C.L.; Busness, K.M.; Olson, N.J.; Reich, F.R.; Stewart, K.B.
1978-03-01
The creep/creep rupture anisotropic properties of Zircaloy were determined and compared by analytical techniques with ramp-pressure and ramp-temperature test results. Tests were performed over the temperature range of 600/sup 0/F (589 K) to 2200/sup 0/F (1477 K), with the emphasis on the 800/sup 0/F (700 K) to 2000/sup 0/F (1366 K) temperature levels in low pressure air (6.5 x 10/sup -5/ atm) and in a 1 atm mixture of 20% oxygen, 80% argon. Stress levels of 60 to 95% of the ultimate tensile stress were used for the majority of the tests at each of the temperature levels tested, with selected tests performed as low as 30% of the ultimate tensile stress. Biaxial and uniaxial testing modes were used to evaluate the anisotropic deformation behavior. The combination of test results and predictive-analysis techniques developed as part of this program make it possible to predict the transient deformation of reactor fuel cladding during simulated LOCA conditions. Results include creep/creep rupture strain numerical constitutive relationships out to 120 seconds, computer codes and ramp test data.
Common creep deformation properties among casts of type 316 stainless steel at practical stresses
International Nuclear Information System (INIS)
Although nonlinear finite element analysis is now well established as a computational technique, the usefulness of its detailed numerical predictions is limited by the reliablility of the constitutive equations and hence upon the underlying material data. Creep deformation data are usually required for calculations at moderate stresses and long times for which it is impractical to test in detail for all casts employed in constructions. The alternatives are extrapolated data from accelerated tests or existing data for other casts. These possibilities are examined here in terms of the regularity of creep behaviour among casts at moderate stresses and for indivual casts at low and high stresses. It is suggested that the former regularity is greater and hence that inter-cast comparison with limited testing of the casts of interest may be the best course for determining creep properties for use in finite element analysis. (orig./GL)
Temperature dependence of deformation vs. strength properties of radiation-crosslinked polyethylene
International Nuclear Information System (INIS)
The authors have studied the deformation vs. strength properties of radiation-crosslinked low-density polyethylene irradiated by ? irradiation up to doses from 5.0 sm-bullet 104 to 1.0 sm-bullet 106 Gy. The authors present the elongation diagrams taken at temperatures below and above the melting point of the polymer. The authors have obtained the dependences of the breaking stress and the pre-break elongation of the polymer on the irradiation doses and the testing temperature. Based on the kinetic lifetime equation, The authors calculated the values of the activation energy for mechanical fracture and the structure-sensitive coefficient ?. The authors show that in the crystalline state the strength of radiation-crosslinked polyethylene is determined by the chemical interactions along the chain of polymer macromolecules; and in molten polyethylene, by the crosslinks between the macromolecules. 8 refs., 4 figs., 1 tab
Energy Technology Data Exchange (ETDEWEB)
Yang Xiaoping [Group of Computational Condensed Matter Physics, National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China) and Department of Physics, Huainan Normal University, Huainan, Anhui 232001 (China)]. E-mail: bunnyxp@hotmail.com; Dong Jinming [Group of Computational Condensed Matter Physics, National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China)
2004-09-20
The electronic and transport property of a radially deformed double-walled carbon nanotube (DWNT) intramolecular junction (IMJ) has been studied by the tight-binding (TB) model combined with the first-principle calculations. The geometrical structures of the DWNT IMJ have been first optimized in energy by the universal force field (UFF) method. It is found that when heavily squashed, the DWNT will become an insulator-coated metallic wire, and the conductance near the Fermi level has been significantly changed by the radial squash. Specially, several resonance conductance peaks appear at some energies in the conduction band of the squashed DWNT IMJ. Finally, we have also investigated the conductance variation due to change of the length of the central semiconductor in the squashed DWNT IMJ. Furthermore, a promising pure carbon nanoscale electronic device is proposed based on the DWNT IMJ.
Langdon, Terence G.
Processing through the application of severe plastic deformation (SPD) provides a very attractive tool for the production of bulk ultrafine-grained materials. These materials typically have grain sizes in the submicrometer or nanometer ranges and they exhibit high strength at ambient temperature and, if the ultrafine grains are reasonably stable at elevated temperatures, they have a potential for use in superplastic forming operations. Several procedures are now available for applying SPD to metal samples but the most promising are Equal-Channel Angular Pressing (ECAP) and High-Pressure Torsion (HPT). This paper examines the basic principles of ECAP and HPT and describes some of the properties that may be achieved using these processing techniques.
Tensile properties of a nickel-base alloy subjected to surface severe plastic deformation
Energy Technology Data Exchange (ETDEWEB)
Tian, J.W. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN (United States); Dai, K. [Quality Engineering and Software Technology, East Hartford, CT 06108 (United States); Villegas, J.C. [Intel Corporation, Chandler, AZ (United States); Shaw, L. [Department of Chemical, Materials and Biomolecular Engineering, University of Connecticut, Storrs, CT (United States)], E-mail: leon.shaw@uconn.edu; Liaw, P.K. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN (United States); Klarstrom, D.L. [Haynes International, Inc., Kokomo, IN (United States); Ortiz, A.L. [Departamento de Ingenieria Mecanica, Energetica y de los Materiales, Universidad de Extremadura, 06071 Badajoz (Spain)
2008-10-15
A surface severe plastic deformation (S{sup 2}PD) method has been applied to bulk specimens of HASTELLOY C-2000 alloy, a nickel-base alloy. The mechanical properties of the processed C-2000 alloy were determined via tensile tests and Vickers hardness measurements, whereas the microstructure was characterized using scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. The improved tensile strength was related to the nanostructure at the surface region, the residual compressive stresses, and the work-hardened surface layer, all of which resulted from the S{sup 2}PD process. To understand the contributions of these three factors, finite element modeling was performed. It was found that the improved tensile strength could be interpreted based on the contributions of nano-grains, residual stresses, and work hardening.
International Nuclear Information System (INIS)
A systematic study of the ground-state properties of even-even rare earth nuclei has been performed in the framework of the Relativistic Mean-Field (RMF) theory using the parameter set NL-Sh. Nuclear radii, isotope shifts and deformation properties of the heavier rare-earth nuclei have been obtained, which encompass atomic numbers ranging from Z=60 to Z=70 and include a large range of isospin. It is shown that RMF theory is able to provide a good and comprehensive description of the empirical binding energies of the isotopic chains. At the same time the quadrupole deformations ?2 obtained in the RMF theory are found to be in good agreement with the available empirical values. The theory predicts a shape transition from prolate to oblate for nuclei at neutron number N=78 in all the chains. A further addition of neutrons up to the magic number 82 brings about the spherical shape. For nuclei above N-82, the RMF theory predicts the well-known onset of prolate deformation at about N-88, which saturates at about N-102. The deformation properties display an identical behaviour for all the nuclear chains. A good description of the above deformation transitions in the RMF theory in all the isotopic chains leads to a successful reproduction of the anomalous behaviour of the empirical isotopic shifts of the rare-earth nuclei. The RMF theory exhibits a remarkable success in providing a unified and microscopic description of various empirical data. (orig.)
International Nuclear Information System (INIS)
The influence of severe plastic torsion straining under pressure on the structure and magnetic properties of the alloy Pr20 Fe 73.5 N 5 Cu 1.5 at % is considered in the present work. Deformation results in the formation of an ultrafine-gained structure and subsequent annealing leads to an increase in coercivity to 1500 kA/m. (authors)
Fleitout, L.; Garaud, J.; Cailletaud, G.; Vigny, C.; Simons, W. J.; Ambrosius, B. A.; Trisirisatayawong, I.; Satirapod, C.; Geotecdi Song
2011-12-01
The giant seism of Aceh (december 2004),followed by the Nias and Bengkulu earthquakes, broke a large portion of the boundary between the Indian ocean and the Sunda block. For the first time in history, the deformations associated with a very large earthquake can be followed by GPS, in particular by the SEAMERGE (far-field) and SUGAR (near-field) GPS networks. A 3D finite element code (Zebulon-Zset) is used to model both the cosismic and the postseismic deformations. The modeled zone is a large portion of spherical shell around Sumatra extanding over more than 60 degrees in latitude and longitude and from the Earth's surface to the core-mantle boundary. The mesh is refined close to the subduction zone. First, the inverted cosismic displacements on the subduction plane are inverted for and provide a very good fit to the GPS data for the three seisms. The observed postseismic displacements, non-dimensionalized by the cosismic displacements, present three very different patterns as function of time: For GPS stations in the far-field, the total horizontal post-seismic displacement after 4 years is as large as the cosismic displacement. The velocities vary slowly over 4 years. A large subsidence affects Thailand and Malaysia. In the near-field, the postseismic displacement reaches only some 15% of the cosismic displacement and it levels off after 2 years. In the middle-field (south-west coast of Sumatra), the postseismic displacement also levels-off with time but more slowly and it reaches more than 30% of the cosismic displacement after four years. In order to fit these three distinct displacement patterns, we need to invoke both viscoelastic deformation in the asthenosphere and a low-viscosity wedge: Neither the vertical subsidence nor the amplitude of the far-field horizontal velocities could be explained by postseismic sliding on the subduction interface. The low viscosity wedge permits to explain the large middle-field velocities. The viscoelastic properties of the asthenosphere are consistent with a Burger rheology with a transient creep represented by a Kelvin-Voigt element with a viscosity of 3.1018Pas and ? Kelvin}=? {elastic/3. A second Kelvin-Voigt element with very limited amplitude may explain some characteristics of the short time-scale signal. The viscosity of the low viscosity wedge is also of the order of 3. 1018 Pas. The near-field displacements are not explained by viscoelastic relaxation and post-seismic slip on the fault plane (15% of the cosismic slip) occured in the months after the earthquakes. These large post-seismic deformations affect the deviatoric stresses in the whole Sunda-block. They also imply sizable far-field interseismic deformations.
Energy Technology Data Exchange (ETDEWEB)
Morgan, M.; Tosten, M.; Chapman, G.
2013-09-06
The deformation and fracture toughness properties of forged stainless steels pre-charged with tritium were compared to the deformation and fracture toughness properties of the same steels heat treated at 773 K or 873 K and precharged with hydrogen. Forged stainless steels pre-charged with tritium exhibit an aging effect: Fracture toughness values decrease with aging time after precharging because of the increase in concentration of helium from tritium decay. This study shows that forged stainless steels given a prior heat treatment and then pre-charged with hydrogen also exhibit an aging effect: Fracture toughness values decrease with increasing time at temperature. A microstructural analysis showed that the fracture toughness reduction in the heat-treated steels was due to patches of recrystallized grains that form within the forged matrix during the heat treatment. The combination of hydrogen and the patches of recrystallized grains resulted in more deformation twinning. Heavy deformation twinning on multiple slip planes was typical for the hydrogen-charged samples; whereas, in the non-charged samples, less twinning was observed and was generally limited to one slip plane. Similar effects occur in tritium pre-charged steels, but the deformation twinning is brought on by the hardening associated with decay helium bubbles in the microstructure.
International Nuclear Information System (INIS)
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 -196 C to 1,000 C, and strain rate from 10-3 s-1 to 8,000 s-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
Energy Technology Data Exchange (ETDEWEB)
Yu Xiaohui, E-mail: xiaohui@lanl.gov [Department of Physics, University of Science and Technology of China, Hefei 230026 (China); LANSCE Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); National Lab for Condensed Matter Physics, Institute of Physics, CAS, Beijing 100080 (China); Zhang Jianzhong [LANSCE Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Wang Liping [Mineral Physics Institute, State University of New York, Stony Brook, NY 11794 (United States); Ding Zejun [Department of Physics, University of Science and Technology of China, Hefei 230026 (China); Jin Changqing [National Lab for Condensed Matter Physics, Institute of Physics, CAS, Beijing 100080 (China); Zhao Yusheng, E-mail: yzhao@lanl.gov [LANSCE Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)
2011-05-15
Highlights: > Yield strength of nano-Fe (2.0 GPa) is 15 times higher than that of micron-Fe (0.13 GPa). > Compressive deformation does not build up additional dislocations in nano-Fe. > Pressure induced dislocation annihilation in micron-Fe during compression. > Dislocation annihilation is a dominant mechanism for plastic energy dissipation. - Abstract: We present a comparative study of the mechanical properties of body-centered cubic nanocrystalline iron (nano-Fe) and microcrystalline iron (micro-Fe) by in situ high-pressure synchrotron X-ray diffraction under triaxial compression. For nano-Fe with a starting high dislocation density of 10{sup 16} m{sup -2}, the peak broadening is almost reversible upon unloading from 8.6 GPa to atmospheric pressure, indicating that no additional dislocations are built up during compressive deformation inside grains, at grain boundaries or twin boundaries. Furthermore, an orientation-dependent surface strain is found to be stored in the surface layer of the bcc nano-Fe, which is in agreement with the core-shell model of the nanocrystals. For micro-Fe, a significant and continuous peak sharpening and the associated work softening were observed after the sample is yielded at pressures above 2.0 GPa, which can be presumably attributed to a pressure-induced dislocation annihilation. This finding/interpretation supports the hypothesis that the annihilation of dislocations is one of the dominant mechanisms underlying the plastic energy dissipation. The determined yield strength of 2.0 GPa for nano-Fe is more than 15 times higher than that for micro-Fe (0.13 GPa), indicating that the nanoscale grain-size reduction is a substantially more effective strengthening mechanism than conventional carbon infusion in iron.
International Nuclear Information System (INIS)
The features of the coarse-grained structure transformation into the nanocrystalline one in the process of the intensive plastic deformation through torsion under the quasi-hydrostatic pressure of 6 GPa at the room temperature is considered on the Kh20N80 alloy. The effect of the intensive plastic deformation on the alloy structure and properties is studied through the methods of the electron microscopy, X-ray structural analysis and microhardness measurement. It is shown that the obtained nanocrystalline structure is the nonequilibrium one and it maintains the thermal stability up to heating temperature no exceeding 500 deg C
Tarantola, Alexandre; Diamond, Larryn W.
2015-04-01
A well developed theoretical framework is available in which paleofluid properties, such as chemical composition and density, can be reconstructed from fluid inclusions in minerals that have undergone no ductile deformation. Fluid inclusions are known to reequilibrate during strong post-entrapment changes in hydrostatic confining pressure (e.g. Sterner and Bodnar 1989). The present study extends this framework to encompass fluid inclusions hosted by quartz that has undergone weak ductile deformation following fluid entrapment. Recent piston-cylinder experiments (Griggs apparatus) made on single quartz crystals have shown that such deformation causes inclusions to become dismembered into clusters of irregularly shaped relict inclusions surrounded by planar arrays of tiny, new-formed (neonate) inclusions (Diamond et al. 2010; Tarantola et al. 2010, 2012). Comparison of the experimental samples with a naturally sheared quartz vein from Grimsel Pass, Central Alps, Switzerland, reveals striking similarities. This strong concordance justifies applying the experimentally derived rules of fluid inclusion behaviour to nature. Thus, planar arrays of dismembered inclusions defining cleavage planes in quartz may be taken as diagnostic of small amounts of intracrystalline strain. Deformed inclusions preserve their pre-deformation concentration ratios of gases to electrolytes, but their H2O contents typically have changed. Morphologically intact inclusions, in contrast, preserve the pre-deformation composition and density of their originally trapped fluid. The orientation of the maximum principal compressive stress (?1) at the time of shear deformation can be derived from the pole to the cleavage plane within which the dismembered inclusions are aligned. Finally, the density of neonate inclusions is commensurate with the pressure value of ?1 at the temperature and time of deformation. This last rule offers a means to estimate magnitudes of shear stresses from fluid inclusion studies. Application of this new paleopiezometer approach to the Grimsel vein yields a differential stress (?1 - ?3) of ~300 MPa at 390 ± 30 °C during late Miocene NNW-SSE orogenic shortening and regional uplift of the Aar Massif. This differential stress resulted in strain-hardening of the quartz at very low total strain (Petrol. 160, 845-864. Sterner, S.M. and Bodnar, R.J., 1989. Synthetic fluid inclusions-VII. Re-equilibration of fluid inclusions in quartz during laboratory-simulated metamorphic burial and uplift. J. Metamorph. Geol., 7, 243¬-260. Tarantola, A., Diamond, L.W., Stünitz, H., 2010. Modification of fluid inclusions in quartz by deviatoric stress. I: Experimentally induced changes in inclusion shapes and microstructures. Contrib. Mineral. Petrol. 160, 825-843. Tarantola, A., Diamond, L.W., Stünitz, H., Thust, A., Pec, M., 2012. Modification of fluid inclusions in quartz by deviatoric stress. III: Influence of principal stresses on inclusion density and orientation. Contrib. Mineral. Petrol. 164, 527-550.
Noda, H.
2004-12-01
Thermal expansion and pressurization of pore water may effectively reduce frictional resistance during slip at high strain rate for faults with impermeable clayey material in shallow depth (parameter in this process because the distribution of excess pore pressure is roughly equal to the width of deformation zone for relatively impermeable faults and pore pressure at the center rises more rapidly for thinner cases. In this study, dynamic rupture propagation simulation with thermal pressurization based on measured hydraulic properties of active faults demonstrates the importance of width of deformation zone. In the case that hydraulic properties of Hanaore fault in Southwest Japan (relatively impermeable) is used, when 100m radius asperity is assumed in which initial shear stress is set as static frictional level (0.6) and dynamic frictional coefficient is assumed to be 0.4, rupture velocity is proved sensitive to the width of deformation zone when it is less than 20mm under condition of 3km depth. When deformation width is reduced to 5mm, rupture velocity in direction of mode 2 exceeds S-wave velocity. This study also shows the importance of hydraulic properties by comparing results of a relatively impermeable fault and a permeable fault at different depths.
Plasma resistivity measurements in the Wisconsin levitated octupole
International Nuclear Information System (INIS)
Resistivity measurements parallel to the magnetic field were made on gun injected plasmas ranging in density from 109cm-3 to 101parallelcm-3 in the Wisconsin levitated octupole with toroidal and poloidal magnetic fields. The 109cm-3 plasma was collisionless with lambda/sub mfp/ > 100 mirror lengths, had T/sub e/ = 10 eV, T/sub i/ = 30 eV and was found to have anomalous resistivity scaling like eta = ?T/sub e//n/sub e/ when E/sub parallel/ > E/su c/ is the Dreicer critical field. The 1012cm-3 plasma was collisional with lambda/sub mfp/ < mirror length, had T/sub e/ = T/sub i/ approx. = .2 eV and was found to have Spitzer resistivity when E/sub parallel/ < E/sub c/
Deformed configurations, band structures and spectroscopic properties of $N = 50$ Ge and Se nuclei
Indian Academy of Sciences (India)
S K Ghorui; C R Praharaj
2014-04-01
The deformed configurations and rotational band structures in $N=50$ Ge and Se nuclei are studied by deformed Hartree–Fock with quadrupole constraint and angular momentum projection. Apart from the `almost’ spherical HF solution, a well-deformed configuration occurs at low excitation. A deformed well-mixed $\\Omega = 1/2^+$ neutron orbit comes down in energy (from the shell above $N = 50$) to break the $N = 50$ spherical shell closure. A = 7? isomer is predicted in 84Se at fairly low excitation energy. At higher excitation energies (8 MeV), a deformed band with = 7/2+–1/2? (based on $h_{11/2}$) neutron 1p–1h excitation, for 82Ge and 84Se, is shown in our calculation. Our study gives insight into possible deformed structures at spherical shell closure.
Simulations of octupole compensation of head-tail instability at the Tevatron
Energy Technology Data Exchange (ETDEWEB)
Meiqin Xiao; Tanaji Sen; Frank Schmidts
2003-05-28
The proton lifetime in the Tevatron depends sensitively on chromaticities. Too low chromaticities can make the beam unstable due to the weak head-tail instability. One way to compensate this effect is to introduce octupoles to create a larger amplitude dependent betatron tune spread. However, the use of octupoles will also introduce additional side effects such as second order chromaticity, differential tune shifts and chromaticities on both proton and anti-proton helices. The non-linear effects may also reduce the dynamic aperture. There are 67 octupoles in 4 different circuits in the Tevatron which may be used for this purpose. We report on a simulation study to find the best combinations of polarities and strengths of the octupoles.
Two-phonon-octupole excitation in 208Pb
International Nuclear Information System (INIS)
In the framework of the present thesis quasi-elastic processes in the reactions 206 Pb+208 Pb and 208 Pb+208 Pb were studied at an incident energy slightly above the Coulomb barrier (6.2 MeV/u) were studed. By means of the measured Particle-gamma correlations the quasi-elastic collisions were separated from the deep inelastic ones. Determined were the absolute cross sections and angular distributions of the exitation by inelastic collisions as well as by one- and two-neutron transfer. For the states excited by inelatic scattering the multiplicities of the ? quanta emitted in their decay were experimentally determined. The measured angular distributions of the inelastic reactions were compared with CCBA calculations. As most important result of this thesis the experimental detection of a member of the 2-phonon-octupole multiplet is to be considered. A hitherto unknown ? transition in the spectrum of -2-0-8 Pb with an energy of 2.485 MeV was detected. Because of the measured ?? coincidence ratios in 208 Pb this transition was assigned to the level scheme of 208Pb. Its decay to the 1-phonon state 3- pursues via an E1-transition to the 5- -state and a following E2-transition. The angular distribution of the 2-phonon-octupole state was calculated in the framework of the CCBA and compared with the experiment. The comparison with the CCBA calculation indicates a spin of I?=6+ or 4+ . The experimental angular distributions of the one-neutron transfer reactions to 207 Pb and 209 Pb were compared with DWBA calculations. (orig./HSI)
Effects of deformation on microstructure and mechanical properties of a Cu-Al-Ni shape memory alloy
International Nuclear Information System (INIS)
In Cu-11.92 wt.%Al-3.78 wt.%Ni shape memory alloy, the influence of deformation and thermal treatments on the microstructure and mechanical properties under the compression test were studied by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). Experiments show that the mechanical properties of the alloy can be enhanced by convenient heat treatments. The alloy exhibits good mechanical properties with high ultimate compression strength and ductility after annealing at high temperature. However, it exhibits brittle fracture and dramatic strain hardening, with linear stress-strain behavior after annealing at low temperature. The changes in the mechanical properties have been linked to the evolution of the degree of order, occurrence of precipitation, and variation of the grain size. From microstructural observations, it is seen that the ?1' (18R) and ?1' (2H) martensite phases coexist at different fractions in the undeformed and deformed states. Deformation induces the changes between the ?1' and ?1' martensites and deformation-induced martensites form at preferred orientations as mechanical twins. The ?1' martensite variants are twin-related with respect to the (1-bar 2-bar 8)18R mirror plane and a new orientation relationship for these twin variants is derived as (1-bar 2-bar 8)A-parallel (1-bar 2-bar 8)C: [4-bar 61] A-parallel [4-bar 61]C. Additionally, an increase in the amount of deformation causes martensite reorientation, de-twinning, and dislocation generation; also, the martensite plates are seen to have rearranged in the same orientation to be parallel with each other
Teki?, Jasmina; Hu, Bambi
2010-03-01
Properties of the dynamical-mode-locking phenomena are studied in the ac driven overdamped Frenkel-Kontorova model with deformable substrate potential. Appearance of very large subharmonic steps due to deformation of the substrate potential significantly influences the stability and existence of harmonic steps. Strong correlation among harmonic and subharmonic steps has been observed in which the larger the width of half-integer steps, the smaller that of harmonic steps. Amplitude dependence of harmonic steps significantly changes with the deformation of the potential where deviation from the well-known Bessel-like oscillations appears. Strong influence of the frequency of the ac driving force on the appearance and size of subharmonic steps has been observed. PMID:20365893
Taskaev, S.; Skokov, K.; Khovaylo, V.; Buchelnikov, V.; Pellenen, A.; Karpenkov, D.; Ulyanov, M.; Bataev, D.; Usenko, A.; Lyange, M.; Gutfleisch, O.
2015-03-01
We report on specific heat and magnetic properties of thin Gd sheets obtained by means of a cold rolling technique. At temperatures well below Curie temperature TC, the cold rolling has a minor impact on the specific heat Cp. However, a well defined ?-type anomaly of Cp seen in the vicinity of TC in a polycrystalline Gd sample is markedly suppressed in the severely deformed samples. Depression of the ? peak is due to a large decrease of magnetization that presumably originates in a local magnetic anisotropy induced by the severe plastic deformation. Results of calculation of magnetocaloric effect from the Cp and magnetization data indicate that the magnetocaloric effect gradually decreases as the degree of plastic deformation increases. This trend is further confirmed by the direct measurements of the adiabatic temperature change ?Tad.
Energy Technology Data Exchange (ETDEWEB)
Young, John P.; Askari, Hesam A.; Heiden, Michael J.; Hovanski, Yuri; Field, David P.; Zbib, Hussein M.
2013-07-08
In recent years magnesium alloys have attracted significant attention as potential candidates to replace many of the heavier metals used in some automotive applications. However, the limited formability of magnesium and its alloys at room temperature has driven interest in the superplastic forming magnesium as an alternative shaping method. Severe plastic deformation techniques have become a well studied method of refining the grain size and modifying the microstructural characteristics of many magnesium alloys to achieve greater superplastic properties. In this study twin roll cast (TRC) AZ31 magnesium alloy was subjected to equal channel angular pressing (ECAP) and friction stir welding (FSW). The influence of these severe plastic deformation processes on the grain size, texture and grain boundary character distribution was investigated to identify the optimum severe plastic deformation process for the superplastic forming of AZ31.
Location of the low-energy isoscalar octupole resonance in 58Ni
International Nuclear Information System (INIS)
The levels of 58Ni have been studied by inelastic proton scattering at E/sub p/ = 65 MeV. The fine structure of the low-energy octupole resonance in 58Ni has been observed. An octupole strength of ?18% of the energy-weighted sum rule is obtained for the fragmented 3- states at E/sub x/<12 MeV. This sum rule strength is consistent with a simple shell model estimate
Energy Technology Data Exchange (ETDEWEB)
Garner, H.; Post, R. S.
1981-02-01
The effective sticking coefficient for low energy (< 30 eV) hydrogen ions on titanium gettered aluminium walls has been measured in the Wisconsin Levitated Octupole. A value of greater than 0.75 was measured. The H/sub 2/ effective sticking coefficient for the same conditions is less than 0.01. Seventy-four percent of the wall area of the Octupole is gettered. The effects of recycling on plasma parameters is also discussed.
Octupole instability induced by rotation in the nuclei 146,148Nd
International Nuclear Information System (INIS)
Levels in 146,148Nd have been populated in the 150Nd (?, ?'xn) reactions. Cascades of enhanced E1 transitions have been observed. B(E1)/B(E2) branching ratios, of the order of 10-6 fm-2 as well as the presence of low energy negative-parity bands indicate strong octupole effects. Shell correction type calculations suggest an explanation in terms of octupole correlations at medium spins. (orig.)
The effects of severe plastic deformation on some properties relevant to Ti implants
Directory of Open Access Journals (Sweden)
Anibal Andrade Mendes Filho
2012-02-01
Full Text Available In some types of surgical implants, such as bone screws and plates, Grade 2 Ti is seriously considered as a replacement for the Ti-6Al-4V alloy. Advantages are lower cost and the absence of Al and V, which have been identified as potentially harmful to human health. The present paper shows that the lower strength of the commercially pure metal can be enhanced by Severe Plastic Deformation followed by conventional cold rolling, so as to reach a strength level higher than the technical requirements applicable to the alloy. This was ascertained by tensile and Vickers hardness tests from which it was concluded that the best combination of properties are obtained by submitting the metal to Equal Channel Angular Pressing (four passes at 300 °C followed by a 70% thickness reduction by cold rolling. Although the present results are valid for the material only, and not for the product considered, that is, bone screws, it appears that this solution is a step towards the replacement of the Ti6-4 alloy by Grade 2 Ti, at least for some types of metallic medical implants.
Changes in microstructure and physical properties of skutterudites after severe plastic deformation.
Rogl, Gerda; Grytsiv, Andriy; Bursik, Jiri; Horky, Jelena; Anbalagan, Ramakrishnan; Bauer, Ernst; Mallik, Ramesh Chandra; Rogl, Peter; Zehetbauer, Michael
2015-02-01
The best p-type skutterudites with ZT > 1.1 so far are didymium (DD) filled, Fe/Co substituted, Sb-based skutterudites. DD0.68Fe3CoSb12 was prepared using an annealing-reacting-melting-quenching technique followed by ball milling and hot pressing. After severe plastic deformation via high-pressure torsion (HPT), no phase changes but particular structural variations were achieved, leading to modified transport properties with higher ZT values. Although after measurement-induced heating some of the HPT induced defects were annealed out, a still attractive ZT-value was preserved. In this paper we focus on explanations for these changes via TEM investigations, Raman spectroscopy and texture measurements. The grain sizes and dislocation densities, evaluated from TEM images, showed that (i) the majority of cracks generated during high-pressure torsion are healed during annealing, leaving only small pores, that (ii) the grains have grown, and that (iii) the dislocation density is decreased. While Raman spectra indicate that after HPT processing and annealing the vibration modes related to the shorter Sb-Sb bonds in the Sb4 rings are more affected than those related to the longer Sb-Sb bonds, almost no visible changes were observed in the pole intensity and/or orientation. PMID:25556702
Evaluation of the Mechanical Properties of AA 6063 Processed by Severe Plastic Deformation
Jafarlou, Davoud Mashhadi; Zalnezhad, Erfan; Hamouda, Abdelmagid Salem; Faraji, Ghader; Mardi, Noor Azizi Bin; Hassan Mohamed, Mohsen Abdelnaeim
2015-05-01
In this study, the mechanical properties, including surface hardness, tensile strength, fatigue, and fretting fatigue behavior of AA 6063 processed by equal channel angular pressing as the most efficient severe shear plastic deformation (SPD) technique, were investigated. Following the SPD process, samples were subjected to heat treatment (HT), hard anodizing (HA), and a combination of HT and HA. Rotating-bending fretting fatigue tests were performed to explore the samples' response to the fretting condition. From the experimental fatigue and fretting fatigue tests, it was apparent that the SPD treatment had a positive effect on enhancing the fatigue and fretting fatigue lives of the samples at low and high-cyclic loads compared with the HT technique by 78 and 67 pct, and 131 and 154 pct respectively. The results also indicate that the SPD + HT technique significantly increased the fatigue and fretting fatigue lives of the samples at high and low cycles by 15.56 and 8.33 pct, and 14.4 and 5.1 pct respectively, compared with the SPD method. HA of AA6063 increased the fatigue and fretting fatigue lives of SPD + HT-processed samples at low cycle by 15.5 and 18.4 pct respectively; however, at high cycle, HA had reverse effects, whereby the fatigue and fretting fatigue lives of SPD + HT-processed samples decreased by 16.7 and 30 pct, respectively.
Yu, Xiaohui; Zhang, Jianzhong; Wang, Liping; Zhao, Yusheng
2011-03-01
We present a comparative study of mechanical properties of bcc nano-crystalline iron and microncrystalline iron by in-situ high-pressure synchrotron x-ray diffraction under tri-axial compression. For nano-Fe with a starting high dislocation density of 1016 m -2 , the peak broadening is almost reversible upon unloading from 8.6 GPa to ambient pressure, indicating that no additional dislocations are built up during compressive deformation inside grains, at grain boundaries or twin boundaries. Furthermore, an orientation dependent surface strain is found to be stored in the surface layer of the bcc nano Fe, which is in agreement with the core-shell model of the nano crystals. For micron-Fe, a significant and continuous peak sharpening and the associated work softening were observed after the sample is yielded at pressures above 2.0 GPa, which can be presumably attributed to a pressure-induced dislocation annihilation. This finding/interpretation supports the hypothesis that the annihilation of dislocations is one of the dominant mechanisms underlying the plastic energy dissipation. The determined yield strength of 2.0 GPa for nano-Fe is more than 15 times higher than that for micron-Fe (0.13 GPa), indicating that the nano scale grain-size reduction is a substantially more effective strengthening mechanism than the conventional carbon infusion in iron.
The effects of severe plastic deformation on some properties relevant to Ti implants
Scientific Electronic Library Online (English)
Anibal Andrade, Mendes Filho; Vitor Luiz, Sordi; Maurizio, Ferrante.
2012-02-01
Full Text Available In some types of surgical implants, such as bone screws and plates, Grade 2 Ti is seriously considered as a replacement for the Ti-6Al-4V alloy. Advantages are lower cost and the absence of Al and V, which have been identified as potentially harmful to human health. The present paper shows that the [...] lower strength of the commercially pure metal can be enhanced by Severe Plastic Deformation followed by conventional cold rolling, so as to reach a strength level higher than the technical requirements applicable to the alloy. This was ascertained by tensile and Vickers hardness tests from which it was concluded that the best combination of properties are obtained by submitting the metal to Equal Channel Angular Pressing (four passes at 300 °C) followed by a 70% thickness reduction by cold rolling. Although the present results are valid for the material only, and not for the product considered, that is, bone screws, it appears that this solution is a step towards the replacement of the Ti6-4 alloy by Grade 2 Ti, at least for some types of metallic medical implants.
Transient deformation properties of Zircaloy for LOCA simulation. Final report, Volume 1. [BWR; PWR
Energy Technology Data Exchange (ETDEWEB)
Hann, C.R.; Mohr, C.L.; Busness, K.M.; Olson, N.J.; Reich, F.R.; Stewart, K.B.
1977-12-01
The creep/creep rupture anisotropic properties of Zircaloy were determined and compared by analytical techniques with ramp pressure and ramp temperature test results. Tests were performed over the temperature range of 600/sup 0/F (589 K) to 2200/sup 0/F (1477 K) with the emphasis on the 800/sup 0/F (700/sup 0/K) to 2000/sup 0/F (1366/sup 0/K) temperature levels in low pressure air (6.5 x 10/sup -5/ atm) and in a 1 atm mixture of 20% oxygen, 80% argon. Stress levels of 60 to 95% of the ultimate tensile stress were used for the majority of the tests at each of the temperature levels tested, with selected tests performed as low as 30% of the ultimate tensile stress. Biaxial and uniaxial testing modes were used to evaluate the anisotropic deformation behavior. Results include creep/creep rupture strain numerical constitutive relationships out to 120 seconds, computer codes and ramp test data.
Directory of Open Access Journals (Sweden)
Langdon, T. G.
2008-12-01
Full Text Available The processing of polycrystalline metals through the application of severe plastic deformation is attracting much attention because of the potential for achieving significant grain refinement to the submicrometer or nanometer level. This paper reviews the principles of this type of processing with emphasis on two different techniques: Equal- Channel Angular Pressing and High-Pressure Torsion. Exceptional properties may be achieved from these processes including high strength at ambient temperatures and a rapid superplastic forming capability at elevated temperatures. Some examples are presented demonstrating the potential use of this type of processing.
El procesado de metales policristalinos a través de deformación plástica severa está atrayendo mucha atención, debido al potencial para alcanzar un importante afino de grano a niveles submicrométricos o nanométricos. Esta publicación revisa los principios de este tipo de procesado haciendo hincapié en dos técnicas diferentes: prensado en canal angular y torsión bajo alta presión. Mediante estos procesos, se pueden alcanzar propiedades excepcionales incluyendo alta resistencia a temperatura ambiente y una capacidad de conformación superplástica rápida a elevadas temperaturas. Se presentan algunos ejemplos demostrando el uso potencial de este tipo de procesado.
Energy Technology Data Exchange (ETDEWEB)
X Yu; J Zhang; L Wang; Z Ding; C Jin; Y Zhao
2011-12-31
We present a comparative study of the mechanical properties of body-centered cubic nanocrystalline iron (nano-Fe) and microcrystalline iron (micro-Fe) by in situ high-pressure synchrotron X-ray diffraction under triaxial compression. For nano-Fe with a starting high dislocation density of 10{sup 16} m{sup -2}, the peak broadening is almost reversible upon unloading from 8.6 GPa to atmospheric pressure, indicating that no additional dislocations are built up during compressive deformation inside grains, at grain boundaries or twin boundaries. Furthermore, an orientation-dependent surface strain is found to be stored in the surface layer of the bcc nano-Fe, which is in agreement with the core-shell model of the nanocrystals. For micro-Fe, a significant and continuous peak sharpening and the associated work softening were observed after the sample is yielded at pressures above 2.0 GPa, which can be presumably attributed to a pressureinduced dislocation annihilation. This finding/interpretation supports the hypothesis that the annihilation of dislocations is one of the dominant mechanisms underlying the plastic energy dissipation. The determined yield strength of 2.0 GPa for nano-Fe is more than 15 times higher than that for micro-Fe (0.13 GPa), indicating that the nanoscale grain-size reduction is a substantially more effective strengthening mechanism than conventional carbon infusion in iron.
Mechanical properties and deformation behavior of Ti-5Cr-xFe alloys
International Nuclear Information System (INIS)
The effects of iron on the mechanical properties and deformation behavior of a Ti-5Cr-based system were studied with emphasis on improving the strength/modulus ratio. As-cast Ti-5Cr and a series of Ti-5Cr-xFe (x = 0.1, 0.5, 1, 3 and 5 mass%) alloys prepared by using a dental cast machine were investigated. X-ray diffraction (XRD) for phase analysis was conducted with a diffractometer. Three-point bending tests were performed to evaluate the mechanical properties of all specimens. The fractured surfaces were observed by using scanning electron microscopy (SEM). Moreover, the surface morphology of a post-bending unetched specimen was examined by using an optical microscope. The experimental results indicated that only Ti-5Cr-3Fe and Ti-5Cr-5Fe alloys exhibited ductile properties. The bending moduli of the Ti-5Cr-3Fe and Ti-5Cr-5Fe alloys without an ? phase were lower than those of the Ti-5Cr and Ti-5Cr-xFe alloys with an ? phase. The Ti-5Cr-3Fe alloy exhibited highest bending strength/modulus ratios as large as 25.1, being higher than those of commercially pure titanium (c.p. Ti) by 195% and of the Ti-5Cr alloy by 132%. Moreover, the Ti-5Cr-5Fe alloy also had highest ratios as large as 24.6, being higher than those of c.p. Ti by 189% and of the Ti-5Cr alloy by 128%. Furthermore, the elastically recoverable angles of the Ti-5Cr-3Fe (31.5 deg.) and Ti-5Cr-5Fe (29.6 deg.) alloys were greater than those of c.p. Ti (2.7 deg.) by as much as 1067% and 996%, respectively. The optical micrographs indicated that the surfaces of the Ti-5Cr-3Fe and Ti-5Cr-5Fe alloys were covered with many slip bands. In the current search for better implant materials, the low modulus, ductile property, excellent elastic recovery capability and reasonably high strength (or high strength/modulus ratio) ? phase Ti-5Cr-3Fe and Ti-5Cr-5Fe alloys seem to be promising candidates
International Nuclear Information System (INIS)
Adopted values for the excitation energy, Ex(31-), of the first 3- state of the even-even nuclei are tabulated. Values of the reduced electric-octupole transition probability, B(E3;O1+ ? 31-), from the ground state to this state, as determined from Coulomb excitation, lifetime measurements, inelastic electron scattering, deformation parameters ?3 obtained from angular distributions of inelastically scattered nucleons and light ions, and other miscellaneous procedures are listed in separate Tables. Adopted values for B(E3; O1+ ? 31-) are presented in Table VII, together with the E3 transition strengths, in Weisskopf units, and the product Ex(31-) x B(E3; O1+ ? 31--) expressed as a percentage of the energy-weighted E3 sum-rule strength. An evaluation is made of the reliability of B(E3; O1+ ? 31-) values deduced from deformation parameters ?3. The literature has been covered to March 1988
Raziperchikolaee, Samin
The pore pressure variation in an underground formation during hydraulic stimulation of low permeability formations or CO2 sequestration into saline aquifers can induce microseismicity due to fracture generation or pre-existing fracture activation. While the analysis of microseismic data mainly focuses on mapping the location of fractures, the seismic waves generated by the microseismic events also contain information for understanding of fracture mechanisms based on microseismic source analysis. We developed a micro-scale geomechanics, fluid-flow and seismic model that can predict transport and seismic source behavior during rock failure. This model features the incorporation of microseismic source analysis in fractured and intact rock transport properties during possible rock damage and failure. The modeling method considers comprehensive grains and cements interaction through a bonded-particle-model. As a result of grain deformation and microcrack development in the rock sample, forces and displacements in the grains involved in the bond breakage are measured to determine seismic moment tensor. In addition, geometric description of the complex pore structure is regenerated to predict fluid flow behavior of fractured samples. Numerical experiments are conducted for different intact and fractured digital rock samples, representing various mechanical behaviors of rocks and fracture surface properties, to consider their roles on seismic and transport properties of rocks during deformation. Studying rock deformation in detail provides an opportunity to understand the relationship between source mechanism of microseismic events and transport properties of damaged rocks to have a better characterizing of fluid flow behavior in subsurface formations.
Interplay of inertia and deformability on rheological properties of a suspension of capsules
Krueger, Timm; Harting, Jens
2013-01-01
The interplay of inertia and deformability has a substantial impact on the transport of soft particles suspended in a fluid. However, to date a thorough understanding of these systems is still missing and only a limited number of experimental and theoretical studies is available. We combine the finite-element, immersed-boundary and lattice-Boltzmann methods to simulate three-dimensional suspensions of soft particles subjected to planar Poiseuille flow at finite Reynolds numbers. Our findings confirm that the particle deformation and inclination increase when inertia is present. We observe that the Segr\\'e-Silberberg effect is unstable with respect to the particle deformability. Depending on the deformability and strength of inertial effects, inward or outward lateral migration of the particles takes place. In particular, for increasing Reynolds numbers and strongly deformable particles, distinct flow focusing emerges which is accompanied by a non-monotonic behaviour of the apparent suspension viscosity and th...
Ring, P; Lalazissis, G A
1997-01-01
A Fortran program for the calculation of the ground state properties of axially deformed even-even nuclei in the relativistic framework is presented. In this relativistic mean field (RMF) approach a set of coupled differential equations namely the Dirac equation with potential terms for the nucleons and the Glein-Gordon type equations with sources for the meson and the electromagnetic fields are to be solved self-consistently. The well tested basis expansion method is used for this purpose. Accordingly a set of harmonic oscillator basis generated by an axially deformed potential are used in the expansion. The solution gives the nucleon spinors, the fields and level occupancies, which are used in the calculation of the ground state properties.
International Nuclear Information System (INIS)
Influence of severe plastic deformation by means of equal-channel and complex angular extrusion and of submicrocrystalline (SMC) structure on static tensile strength at room temperature of basic compositions of thermally nonstrengthened and strengthened industrially deformed aluminium alloys (Al-Mg, Al-Mg-Li-Zr) was analyzed. It is shown that a unique combination of their strength and ductility can be achieved by complex treatment including severe plastic deformation and conventional methods of thermal and strain effects in thermally nonstrengthened and low-alloy thermally strengthened alloys. The conclusion is made that imparting SMC structure by means of severe plastic deformation by angular extrusion to most complex-alloyed industrial thermally strengthened alloys to improve their static strength is not effective
Zrnik, J.; Lapovok, R.; Raab, G. I.
2014-08-01
The article focuses on the severe plastic deformation (SPD) of low carbon steel AISI 1010 performed at increased temperature. The grain refinement of ferrite structure is monitored and described with respect to different initial steel structure modified by thermal and thermomechanical (TM) treatment (TM) prior severe plastic deformation. The refinement of coarse initial ferrite structure with grain size in range of 30 - 50 gm resulted from solutioning was conducted then in two steps. Preliminary structure refinement has been achieved due to multistep open die forging process and quite uniform ferrite structure with grain size of the order of gm was obtained. The further grain refinement steel structure was then accomplished during warm Equal Channel Angular Pressing (ECAP phi = 120°) at 300°C, introducing different strain in range of ?ef = 2.6 -4. The change of microstructure in dependence of the effective strain was evaluated by SEM and TEM study of thin foils. The high straining of steel resulted in extensive deformation of ferrite grains and formation of mixture of submicron grains structure in banded deformed structure with dense dislocation network and subgrains. The dynamic polygonization process, due to increased ECAP temperature, modified the submicrocrystalline structure formation. There was only indistinctive difference observed in structure refinement when considering different initial structure of steel. The tensile behaviour was characterized by strength increase followed by softening. None work hardening phenomenon appeared at tensile deformation of deformed bars.
Depalle, Baptiste; Qin, Zhao; Shefelbine, Sandra J; Buehler, Markus J
2015-12-01
Collagen is a ubiquitous protein with remarkable mechanical properties. It is highly elastic, shows large fracture strength and enables substantial energy dissipation during deformation. Most of the connective tissue in humans consists of collagen fibrils composed of a staggered array of tropocollagen molecules, which are connected by intermolecular cross-links. In this study, we report a three-dimensional coarse-grained model of collagen and analyze the influence of enzymatic cross-links on the mechanics of collagen fibrils. Two representatives immature and mature cross-links are implemented in the mesoscale model using a bottom-up approach. By varying the number, type and mechanical properties of cross-links in the fibrils and performing tensile test on the models, we systematically investigate the deformation mechanisms of cross-linked collagen fibrils. We find that cross-linked fibrils exhibit a three phase behavior, which agrees closer with experimental results than what was obtained using previous models. The fibril mechanical response is characterized by: (i) an initial elastic deformation corresponding to the collagen molecule uncoiling, (ii) a linear regime dominated by molecule sliding and (iii) the second stiffer elastic regime related to the stretching of the backbone of the tropocollagen molecules until the fibril ruptures. Our results suggest that both cross-link density and type dictate the stiffness of large deformation regime by increasing the number of interconnected molecules while cross-links mechanical properties determine the failure strain and strength of the fibril. These findings reveal that cross-links play an essential role in creating an interconnected fibrillar material of tunable toughness and strength. PMID:25153614
International Nuclear Information System (INIS)
The ferritic oxide dispersion strengthened alloys are promising candidates for high temperature application materials, in particular for long life core components of advanced nuclear reactors. The aim of this work is to control the microstructure, in order to optimise the mechanical properties. The two ferritic alloys examined here, MA956 and MA957, are obtained by Mechanical Alloying techniques. They are characterised by quite anisotropic microstructure and mechanical properties. We have investigated the influence of hot and cold working processes (hot extrusion, swaging and cold-drawing) and recrystallization heat treatments on deformation textures, microstructures and tensile properties. The aim was to control the size of the grains and their anisotropic shape, using recrystallization heat treatments. After consolidation and hot extrusion, as-received materials present a extremely fine microstructure with elongated grains and a very strong (110) deformation texture with single-crystal character. At that stage of processing, recrystallization temperature are very high (1450 degrees C for MA957 alloy and 1350 degrees C for MA956 alloy) and materials develop millimetric recrystallized grains. Additional hot extrusion induce a fibre texture. Cold-drawing maintains a fibre texture, but the intensity decreases with increasing cold-work level. For both materials, the decrease of texture intensities correspond to a decrease of the recrystallization temperatures (from 1350 degrees C for a low cold-work level to 750 degrees C for 60 % cold-deformation, case of MA956 alloy) and a refinement of the grain size (from a millimetric size to less than an hundred of micrometer). Swaging develop a cyclic component where the intensity increases with increasing deformation in this case, the recrystallization temperature remains always very high and the millimetric grain size is slightly modified, even though cold-work level increases. Technologically, cold-drawing is the only way that permits the decreasing of the recrystallization temperature of several hundred degrees and giving the best compromise between mechanical strength and ductility. (author). 72 refs., 6 appends
Ion-cyclotron-resonance heating in the Wisconsin Levitated Octupole
International Nuclear Information System (INIS)
Ion-cyclotron-resonance heating has been investigated, both experimentally and theoretically, on the Wisconsin Levitated Octupole. Heating of both ions and electrons has been observed. Typically, a two-component ion energy distribution is produced (300 eV and 50 eV) with 500 kW of rf power coupled into a 5 x 1012 cm-3 plasma. Power is coupled to the plasma with an antenna that also serves as the inductor of an oscillator tank circuit. The oscillator is tunable from 1 to 3 MHz and can be applied for periods up to 10 msec. The experiments were performed with hydrogen, gun-injected plasmas. Most of the theortical work presented deals with a calculation that predicts the plasma loading. A slab model is used, and the questions of accessibility, polarization, and damping of the radio-frequency electromagnetic fields are addressed. It is found that cold-plasma theory cannot account for the heating and, therefore, hot-plasma theory is invoked to explain the results. The loading measurements and theoretical predictions are found to be in reasonable agreement
Octupole Focusing Relativistic Self-Magnetometer Electric Storage Ring "Bottle"
Talman, Richard
2015-01-01
A method proposed for measuring the electric dipole moment (EDM) of a charged fundamental particle such as the proton, is to measure the spin precession caused by a radial electric bend field $E_r$, acting on the EDMs of frozen spin polarized protons circulating in an all-electric storage ring. The dominant systematic error limiting such a measurement comes from spurious spin precession caused by unintentional and unknown average radial magnetic field $B_r$ acting on the (vastly larger) magnetic dipole moments (MDM) of the protons. Along with taking extreme magnetic shielding measures, the best protection against this systematic error is to use the storage ring itself, as a "self-magnetometer"; the exact magnetic field average $\\langle B_r\\rangle$ that produces systematic EDM error, is nulled to exquisite precision by orbit position control. By using octupole rather than quadrupole focusing the restoring force can be vanishingly small for small amplitude vertical betatron-like motion yet strong enough at larg...
Fifth-order aberrations in magnetic quadrupole-octupole systems
International Nuclear Information System (INIS)
Explicit integral expressions are given for the fifth-order geometrical aberration coefficients in rectilinear magnetic quadrupole-octupole systems used for the transport of nonrelativistic charged particle beams. The numerical values of the fifth-order geometrical aberration coefficients for a rare earth cobalt (REC) quadrupole doublet are given as an example. In the calculations presented here, the author has used Mathematica on a NeXT computer to generate the results. Mathematica provides options to write expressions in a form suitable for input to TEX, or in formats that can be inserted into C or FORTRAN programs. The expressions in Appendix A and C are generated and put into TEX form by Mathematica. The organization of the paper is as follows. The basic equations used here are given in Sec. II while the paraxial and third-order solutions are given in Sec. III and IV respectively. Explicit integral expressions for the fifth-order geometrical aberration coefficients are given in Sec. V. In Sec. VI, numerical values for the third- and fifth-order geometrical aberration coefficients of a REC quad doublet are given. Finally, some concluding remarks are given in Sec. VII
Observation of the Nuclear Magnetic Octupole Moment of 137Ba+
Hoffman, Matthew
Single trapped ions are ideal systems in which to test atomic physics at high precision, which can in turn be used for searches for violations of fundamental symmetries and physics beyond the standard model, in addition to quantum computation and a number of other applications. The ion is confined in ultra-high vacuum, is laser cooled to mK temperatures, and kept well isolated from the environment which allows these experimental efforts. In this thesis, a few diagnostic techniques will be discussed, covering a method to measure the linewidth of a narrowband laser in the presence of magnetic field noise, as well as a procedure to measure the ion's temperature using such a narrowband laser. This work has led to two precision experiments to measure atomic structure in 138Ba+, and 137Ba+ discussed here. First, employing laser and radio frequency spectroscopy techniques in 138Ba+, we measured the Lande- gJ factor of the 5D5/2 level at the part-per-million level, the highest precision to date. Later, the development of apparatus to efficiently trap and laser cool 137Ba+ has enabled a measurement of the hyperfine splittings of the 5D3/2 manifold, culminating in the observation of the nuclear magnetic octupole moment of 137Ba+.
Te, Jerez A.; Tan, Ming-Liang; Ichiye, Toshiko
2010-05-01
Water structure around sugars modeled by partial charges is compared for soft-sticky dipole-quadrupole-octupole (SSDQO), a fast single-site multipole model, and commonly used multi-site models in Monte Carlo simulations. Radial distribution functions and coordination numbers of all the models indicate similar hydration by hydrogen-bond donor and acceptor waters. However, the new optimized SSDQO1 parameters as well as TIP4P-Ew and TIP5P predict a 'lone-pair' orientation for the water accepting the sugar hydroxyl hydrogen bond that is more consistent with the limited experimental data than the 'dipole' orientation in SPC/E, which has important implications for studies of the cryoprotectant properties of sugars.
Evolution of structure and physical-mechanical properties of iron under deformation
Energy Technology Data Exchange (ETDEWEB)
Bukhvalov, A.B.; Gorkunov, E.S. [Academy of Sciences, Ekaterinburg (Russian Federation). Inst. of Engineering Science
1999-09-01
The dependencies of true yield stresses s on true tensile strain values {epsilon} were experimentally determined on the specimens of technically pure iron after cold rolling and after annealing at different temperatures. The correlations between strain values {epsilon} and coercivity H{sub c} which made a basis for nondestructive evaluation of residual deformations of structural elements and machine components were investigated. It has been shown that there is the unique relation between the yield strength and grain sizes in recrystallized iron and also the disoriented subgrain sizes in polygonized iron. The strain hardening curves of exponential type were reconstructed by a method of approximation for two structural states of iron - recrystallized and polygonized. Under low and medium deformations (before the formation of the neck) the growth of the yield stresses s is mainly caused by the strain hardening. Within the interval of large deformation, as {epsilon} grows, the contribution by tension-shear deformation modes increases. As a result, the dislocation density is increasingly influenced by the formation of the fragmentary structure along the strain axis. The feedback equations {epsilon}(H{sub c}) were derived, that can be used for evaluation of the residual deformation by magnetic nondestructive testing methods. (orig.)
Vajpai, Sanjay Kumar; Sawangrat, Choncharoen; Yamaguchi, Osamu; Ciuca, Octav Paul; Ameyama, Kei
2016-01-01
In the present work, Co-Cr-Mo alloy compacts with a unique bimodal microstructural design, harmonic structure design, were successfully prepared via a powder metallurgy route consisting of controlled mechanical milling of pre-alloyed powders followed by spark plasma sintering. The harmonic structured Co-Cr-Mo alloy with bimodal grain size distribution exhibited relatively higher strength together with higher ductility as compared to the coarse-grained specimens. The harmonic Co-Cr-Mo alloy exhibited a very complex deformation behavior wherein it was found that the higher strength and the high retained ductility are derived from fine-grained shell and coarse-grained core regions, respectively. Finally, it was observed that the peculiar spatial/topological arrangement of stronger fine-grained and ductile coarse-grained regions in the harmonic structure promotes uniformity of strain distribution, leading to improved mechanical properties by suppressing the localized plastic deformation during straining. PMID:26478398
Steel Processing Properties and Their Effect on Impact Deformation of Lightweight Structures
Energy Technology Data Exchange (ETDEWEB)
Simunovic, S
2003-09-23
The objective of the research was to perform a comprehensive computational analysis of the effects of material and process modeling approaches on performance of UltraLight Steel Auto Body (ULSAB) vehicle models. The research addressed numerous material related effects, impact conditions as well as analyzed the performance of the ULSAB vehicles in crashes against designs representing the current US vehicle fleet. This report is organized into three main sections. The first section describes the results of the computational analysis of ULSAB crash simulations that were performed using advanced material modeling techniques. The effects of strain-rate sensitivity on a high strength steel (HSS) intensive vehicle were analyzed. Frontal and frontal offset crash scenarios were used in a finite element parametric study of the ULSAB body structure. Comparisons are made between the crash results using the piece-wise-linear isotropic plasticity strain-rate dependent material model, and the isotropic plasticity material model based on quasi-static properties. The simulation results show the importance of advanced material modeling techniques for vehicle crash simulations due to strain-rate sensitivity and rapid hardening characteristics of advanced high strength steels. Material substitution was investigated for the main frontal crush structure using the material of similar yield stress a significantly different strain-rate and hardening characteristics. The objective of the research presented in Section 2 was to assess the influence of stamping process on crash response of ULSAB vehicle. Considered forming effects included thickness variations and plastic strain hardening imparted in the part forming process. The as-formed thickness and plastic strain for front crash parts were used as input data for vehicle crash analysis. Differences in structural performance between crash models with and without forming data were analyzed in order to determine the effects and feasibility of integration of forming processes and crash models. Computational analysis of vehicle-to-vehicle crashes between ULSAB and conventional car designs is reported in Section 3. The study involved vehicles of comparable weights and dimensions to assess the compatibility of the ULSAB with existing designs. Deformation and acceleration data for crashed vehicles were analyzed. Vehicle-modeling approaches have strong influence on computational results and the requirements for compatibility of models were identified for future research on vehicle-to-vehicle crash modeling.
Lattice Distortion and Octupole Ordering Model in CexLa1-xB6
Kubo, K; Kubo, Katsunori; Kuramoto, Yoshio
2003-01-01
Possible order parameters of the phase IV in CexLa1-xB6 are discussed with special attention to the lattice distortion recently observed. A \\Gamma_{5u}-type octupole order with finite wave number is proposed as the origin of the distortion along the [111] direction. The \\Gamma_8 crystalline electric field (CEF) level splits into three levels by a mean field with the \\Gamma_{5u} symmetry. The ground and highest singlets have the same quadrupole moment, while the intermediate doublet has an opposite sign. It is shown that any collinear order of \\Gamma_{5u}-type octupole moment accompanies the \\Gamma_{5g}-type ferro-quadrupole order, and the coupling of the quadrupole moment with the lattice induces the distortion. The cusp in the magnetization at the phase transition is reproduced, but the internal magnetic field due to the octupole moment is smaller than the observed one by an order of magnitude.
Czech Academy of Sciences Publication Activity Database
Antonova, N.; ?íha, Pavel; Ivanov, I.; Gluhcheva, Y.; Bonchev, G.
Munich : European Society for Clinical Hemorheology and Microcirculation, 2011. s. 13. [Conference of the European Society for Clinical Hemorheology and Microcirculation /16./, Annual Conference of the German Society for Clinical Microcirculation and Hemorheology /30./. 18.06.2011-21.06.2011, Munich] Institutional research plan: CEZ:AV0Z20600510 Keywords : red blood cells * electrical conductivity * deformability Subject RIV: BK - Fluid Dynamics
Mechanical and electrical properties of blood and evaluation of RBC aggregation and deformability.
Czech Academy of Sciences Publication Activity Database
Antonova, N.; ?íha, Pavel; Ivanov, I.; Gluhcheva, Y.
Warsaw : International Centre of Biocybernetics (ICB), 2012 - (Bedzinski, R.; Petrtyl, M.), s. 28-32 [ Current trends in development of implantable tissue structures. Warsaw (PL), 18.04.2012-20.04.2012] Institutional support: RVO:67985874 Keywords : apparent viscosity * conductivity * dextrans * glutaraldehyde * RBC aggregation * RBC deformability Subject RIV: JB - Sensors, Measurment, Regulation
Plasma Confinement in a Toroidal Octupole Magnetic Field
International Nuclear Information System (INIS)
The confinement of low-density (n = 109 cm-3) collisionless plasmas with Ti ? 40 eV, Te ? 10 eV produced by gun injection or with Te ? 1 eV. Ti -3of the Bohm diffusion coefficient which was not large enough to produce the observed radial loss. Studies were also made to determine the importance of low-frequency fluctuations or convective cells which may have been produced by injection, magnetic field perturbations or azimuthal density variations. The addition of a toroidal magnetic field decreased the lifetime slightly and generated large-scale convective cells in the shearless layer near the plasma surface. Currents parallel to the magnetic field have been observed which must be considered in determining the cause of increased fluctuation with the increase of the toroidal field. The mechanical supports were also guarded with magnetic dipoles in the manner proposed by Lehnert. The plasma flux to one of the supports was reduced for the hot ion plasma by an order of magnitude when there was one ion gyroradius between the mechanical support and the guard field separatrix. However, the plasma flux along the guard field separatrix increased to the value of the original support flux and there was a negligible ( ? 20%) improvement of the lifetime. An inductively excited, magnetically force-free octupole is being assembled with transiently withdrawn supports to eliminate the plasma loss to hoop supports. The device will provide at least 10 msec of experimental time during which only 5% of the magnetic flux diffuses into the internal hoops. 100 eV protons will have 15 gyroradii on each side of the separatrix. (author)
International Nuclear Information System (INIS)
The relationship between the local shape of an unstable disturbance and the basic deformation field has been put forward by Mak and Cai as a general condition for barotropic instability of a zonally varying nondivergent basic flow. The general condition states that an unstable disturbance has to be elongated locally at an angle of less than 45 degrees along the axis of contraction of the basic deformation field. The conventional condition for barotropic instability of a zonally uniform basic flow (an unstable disturbance necessarily leans against the basic shear) is a special case of the general condition. To physically interpret the general condition, we have analyzed the immediate subsequent evolution of a localized elliptic-shaped disturbance (defined in terms of streamfunction) embedded in a purely deformation flow. The localized disturbance has the minimum kinetic energy and enstrophy when its shape is circular. Under the influence of the basic deformation, the disturbance tends to shrink along the axis of contraction and to expand along the axis of dilatation. Hence, the disturbance with the major axis along the axis of contraction would deform toward a circle shape. The change in eccentricity of such a disturbance alone acts to reduce its total energy and enstrophy. Because of the conservation constraint of the total perturbation enstrophy, the amplitude of the disturbance has to increase as its eccentricity decreases. The energy change due to the change in amplitude overwhelms that resulting from the change in eccentricity. Therefore, the overall kinetic energy of the localized disturbance tends to increase with time during the course of its evolution. The same arguments also explain why the disturbance with major axis along the axis of dilatation is decaying. 9 refs., 3 figs
Specifications of the octupole magnets required for the ATF2 ultra-low ?* lattice
International Nuclear Information System (INIS)
The Accelerator Test Facility 2 (ATF2) aims to test the novel chromaticity correction for higher chromaticity lattices as the one of CLIC. To this end the ATF2 ultra-low ?* lattice is designed to vertically focus the beam at the focal point or usually referred to as interaction point (IP), down to 23 nm. However when the measured multipole components of the ATF2 magnets are considered in the simulations, the evaluated spot sizes at the IP are well above the design value. The designed spot size is effectively recovered by inserting a pair of octupole magnets. In this note we address the technical specifications required for these octupole magnets
Directory of Open Access Journals (Sweden)
Dave Maharaj
2014-06-01
Full Text Available Nanoscale research of bulk solid surfaces, thin films and micro- and nano-objects has shown that mechanical properties are enhanced at smaller scales. Experimental studies that directly compare local with global deformation are lacking. In this research, spherical Au nanoparticles, 500 nm in diameter and 100 nm thick Au films were selected. Nanoindentation (local deformation and compression tests (global deformation were performed with a nanoindenter using a sharp Berkovich tip and a flat punch, respectively. Data from nanoindentation studies were compared with bulk to study scale effects. Nanoscale hardness of the film was found to be higher than the nanoparticles with both being higher than bulk. Both nanoparticles and film showed increasing hardness for decreasing penetration depth. For the film, creep and strain rate effects were observed. In comparison of nanoindentation and compression tests, more pop-ins during loading were observed during the nanoindentation of nanoparticles. Repeated compression tests of nanoparticles were performed that showed a strain hardening effect and increased pop-ins during subsequent loads.
Maharaj, Dave; Bhushan, Bharat
2014-01-01
Nanoscale research of bulk solid surfaces, thin films and micro- and nano-objects has shown that mechanical properties are enhanced at smaller scales. Experimental studies that directly compare local with global deformation are lacking. In this research, spherical Au nanoparticles, 500 nm in diameter and 100 nm thick Au films were selected. Nanoindentation (local deformation) and compression tests (global deformation) were performed with a nanoindenter using a sharp Berkovich tip and a flat punch, respectively. Data from nanoindentation studies were compared with bulk to study scale effects. Nanoscale hardness of the film was found to be higher than the nanoparticles with both being higher than bulk. Both nanoparticles and film showed increasing hardness for decreasing penetration depth. For the film, creep and strain rate effects were observed. In comparison of nanoindentation and compression tests, more pop-ins during loading were observed during the nanoindentation of nanoparticles. Repeated compression tests of nanoparticles were performed that showed a strain hardening effect and increased pop-ins during subsequent loads. PMID:24991519
Indian Academy of Sciences (India)
S K Ghosh; D Mahata; R Roychaudhuri; R Mondal
2012-10-01
The present study deals with the effect of rolling deformation and solution treatment on the microstructure and mechanical properties of a cast duplex stainless steel. Cast steel reveals acicular/Widmanstätten morphology as well as island of austenite within the -ferrite matrix. Hot rolled samples exhibit the presence of lower volume percent of elongated band of -ferrite (?40%) and austenite phase which convert into finer and fragmented microstructural constituents after 30% cold deformation. By the solution treatment, the elongated and broken crystalline grains recrystallize which leads to the formation of finer grains (<10 m) of austenite. X-ray diffraction analysis has corroborated well with the above-mentioned microstructural investigation. Enhancement in hardness, yield strength and tensile strength values as well as drop in percent elongation with cold deformation increases its suitability for use in thinner sections. 30% cold rolled and solution treated sample reveals attractive combination of strength and ductility (25.22 GPa%). The examination of fracture surface also substantiates the tensile results. The sub-surface micrographs provide the potential sites for initiation of microvoids.
Tidal deformations of a spinning compact object
Pani, Paolo; Maselli, Andrea; Ferrari, Valeria
2015-01-01
The deformability of a compact object induced by a perturbing tidal field is encoded in the tidal Love numbers, which depend sensibly on the object's internal structure. These numbers are known only for static, spherically-symmetric objects. As a first step to compute the tidal Love numbers of a spinning compact star, here we extend powerful perturbative techniques to compute the exterior geometry of a spinning object distorted by an axisymmetric tidal field to second order in the angular momentum. The spin of the object introduces couplings between electric and magnetic deformations and new classes of induced Love numbers emerge. For example, a spinning object immersed in a quadrupolar, electric tidal field can acquire some induced mass, spin, quadrupole, octupole and hexadecapole moments to second order in the spin. The deformations are encoded in a set of inhomogeneous differential equations which, remarkably, can be solved analytically in vacuum. We discuss certain subtleties in defining the multipole mom...
Deformation properties of highly plastic fissured Palaeogene clay - Lack of stress memory?
DEFF Research Database (Denmark)
Krogsbøll, Anette; Hededal, Ole; Foged, Niels Nielsen
2012-01-01
The geological preconsolidation of the Palaeogene clays in Denmark is estimated to 5-8 MPa or more, whereas laboratory and field experiences indicate values between 100 and 3000 kPa. Presumably, the high plasticity clay loses its memory of earlier preloads due to swelling, or as an effect of fissuring or debonding. Based on a large amount of high quality tests on Palaeogene clay partly encountered at Fehmarn Belt the typical deformational behaviour during unloading and swelling is discussed and ...
Directory of Open Access Journals (Sweden)
Yang Fei
2010-11-01
Full Text Available Ti-45Al-9(V, Nb, Y alloys with four different x=V/Nb (atomic ratio x = 1, 1.5, 2 and 3.5 have been prepared, and the microstructures, properties and hot deformation behaviors were investigated. SEM, XRD and TEM results showed that Ti-45Al-9(V, Nb, Y alloys were mainly composed of ?, ?2, and ? phase, and the volume fraction of ? phase increased with the increase of the atomic ratio of V/Nb. The alloys were featured with lamellar microstructure with ? and ? phases locating at the colony boundaries, and some ? precipitates appearing at ?/? interfaces. It was found that the colony size decreased with the increase of x. The alloys exhibited moderate mechanical properties at room temperature, with a yield strength of over 600 MPa, and fractures showed mainly translamellar character. The alloy with x=3.5 exhibited the best deformability at elevated temperature and that with x=1 had superior oxidation resistance at 800 ?.
Elliott, S. J.; Eichhubl, P.; Landry, C. J.
2014-12-01
Fluid flow tends to be restricted perpendicular to deformation bands through the combined effects of mechanical grain size reduction, porosity loss, and preferred cementation relative to the adjacent host rock. Deformation bands that occur in association with reservoir scale faults can impact reservoir-scale fluid flow and fault seal behavior, potentially imparting a permeability anisotropy to reservoir rocks. We use a combination of Hg-intrusion porosimetry, high-resolution 2D-image analysis of pore size distributions, and detailed compositional analyses obtained from integrating petrographic and SEM-based imaging techniques, including SEM-cathodoluminescence, backscattered electron imaging, and energy-dispersive X-ray spectroscopy, to (1) assess the effects of coupled chemical and mechanical processes leading to deformation localization within various detrital compositions [Cedar Mesa, Navajo, and Entrada sandstones] and (2) to quantify the effect of these processes on single and multiphase fluid flow as a function of host rock properties, structural position, and deformation band textural and diagenetic properties. Within each sample, bands of differing kinematic properties and structural style, i.e. shear bands, shear enhanced compaction bands etc., were identified and pre-kinematic pore-filling cements, as well as syn- and post-kinematic cements including various clay minerals, were distinguished for both the host rock and associated deformation bands. Although the deformation bands display a variety of textures and diagenetic attributes, initial petrophysical results suggest that the flow properties - permeability and capillary pressure curves - of the bands in the formations studied are very similar. However, both individual and clustered deformation bands of the Navajo Sandstone contain open or partially cemented cross-cutting fractures that could act as flow pathways across the deformation bands.
Theory and measurement of properties of two-phase materials in the plastic-viscous deformation range
International Nuclear Information System (INIS)
An extensive literature survey shows, that theoretical equations available are inadequate to predict the viscosity of suspensions without limitation of the concentration of the dispersed phase, the shape and orientation of the suspended particles. Based on physically derived and experimentally verified equations for the theoretical prediction of transport and/or field properties of solid two-phase materials with penetration structure, an attempt has been made to predict the viscosity of suspensions and the high temperature creep of two-phase solid materials with the aid of so-called structure parameters. The justification for the treatment of the problem in such a way is given by the consideration of the viscocity as a transport property and by the existing analogies between viscous and viscoplastic deformation. (orig./RW)
Energy Technology Data Exchange (ETDEWEB)
Moenkkoenen, H.; Rantanen, T.; Kuula, H. [WSP Finland Oy, Helsinki (Finland)
2012-05-15
In this report, the rock mechanics parameters of fractures and brittle deformation zones have been estimated in the vicinity of the ONKALO area at the Olkiluoto site, western Finland. This report is an extension of the previously published report: Geometrical and Mechanical properties if the fractures and brittle deformation zones based on ONKALO tunnel mapping, 0-2400 m tunnel chainage (Kuula 2010). In this updated report, mapping data are from 2400-4390 m tunnel chainage. Defined rock mechanics parameters of the fractures are associated with the rock engineering classification quality index, Q', which incorporates the RQD, Jn, Jr and Ja values. The friction angle of the fracture surfaces is estimated from the Jr and Ja numbers. There are no new data from laboratory joint shear and normal tests. The fracture wall compressive strength (JCS) data are available from the chainage range 1280-2400 m. Estimation of the mechanics properties of the 24 brittle deformation zones (BDZ) is based on the mapped Q' value, which is transformed to the GSI value in order to estimate strength and deformability properties. A component of the mapped Q' values is from the ONKALO and another component is from the drill cores. In this study, 24 BDZs have been parameterized. The location and size of the brittle deformation are based on the latest interpretation. New data for intact rock strength of the brittle deformation zones are not available. (orig.)
Octupole Resonance in the AGS at High Intensity: A SIMBAD study
International Nuclear Information System (INIS)
We studied the Octupole (Montague) resonance in the AGS, in its high intensity mode, by tracking with the PIC code SIMBAD. We calculated, turn-by-turn, the betatron tune footprint from the eigenvalues of the one-turn matrix. We show that one should exercise particular caution when the betatron tunes are close together, since the matrix gives ambiguous results at the resonance
Convective cells and their relationship to vortex diffusion in the Wisconsin Levitated Octupole
International Nuclear Information System (INIS)
The purpose of this thesis is two-fold: first, to present floating potential structure for different plasmas and operating parameters in the Wisconsin Levitated Octupole. Second, to show how the observed potential structure can be used, within the framework of vortex diffusion, to account for enhanced diffusion in the appropriate parameter regimes
Examination of different strengths of octupole correlations in neutron-rich Pr and Pm isotopes.
Czech Academy of Sciences Publication Activity Database
Thiamova, G.; Alexa, P.; Hons, Zden?k; Simpson, G.S.
2012-01-01
Ro?. 86, ?. 4 (2012), 044334/1-044334/5. ISSN 0556-2813 R&D Projects: GA ?R GAP203/10/0310 Institutional support: RVO:61389005 Keywords : neutron rich nuclei * octupole correlations Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.715, year: 2012
Energy Technology Data Exchange (ETDEWEB)
Lari Baghal, S.M. [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of); Amadeh, A., E-mail: amadeh@ut.ac.ir [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of); Heydarzadeh Sohi, M. [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of)
2012-04-30
Highlights: Black-Right-Pointing-Pointer The tensile properties of Ni-Co and Ni-Co/SiC deposits were investigated. Black-Right-Pointing-Pointer The SiC particles enhanced tensile strength and ductility of nano-structured composites. Black-Right-Pointing-Pointer The deformation mechanism at low and high strain rates were studied. - Abstract: Ni-Co/SiC nano-composites were prepared via electrodeposition from a modified Watts bath containing SiC particles with average particle size of 50 nm, SDS as surfactant and saccharin as grain refiner in appropriate amounts. The effect of nano-particle incorporation on microstructure, mechanical properties and deformation mechanism of electrodeposits were investigated. The mechanical properties of electrodeposits were investigated by Vickers microhardness and tensile tests. The results indicated that incorporation of SiC particles into a 15 nm Ni-Co matrix had no considerable effect on its microhardness and yield strength, that is, dispersion hardening did not operate in this range of grain size. However it was observed that co-deposition of uniform distributed SiC particles can significantly improve the ultimate tensile strength and elongation to failure of the deposits. Calculation of apparent activation volume from tensile test results at different strain rates proved that incorporation of SiC nano-particles are responsible for stress-assisted activation of GB atoms mechanism that can significantly increase the plasticity. Nano-crystalline Ni-Co matrix showed a mixed mod behavior of ductile and brittle fracture whereas incorporation of SiC particles and increasing the strain rate promoted ductile fracture mode.
International Nuclear Information System (INIS)
Highlights: ? The tensile properties of Ni–Co and Ni–Co/SiC deposits were investigated. ? The SiC particles enhanced tensile strength and ductility of nano-structured composites. ? The deformation mechanism at low and high strain rates were studied. - Abstract: Ni–Co/SiC nano-composites were prepared via electrodeposition from a modified Watts bath containing SiC particles with average particle size of 50 nm, SDS as surfactant and saccharin as grain refiner in appropriate amounts. The effect of nano-particle incorporation on microstructure, mechanical properties and deformation mechanism of electrodeposits were investigated. The mechanical properties of electrodeposits were investigated by Vickers microhardness and tensile tests. The results indicated that incorporation of SiC particles into a 15 nm Ni–Co matrix had no considerable effect on its microhardness and yield strength, that is, dispersion hardening did not operate in this range of grain size. However it was observed that co-deposition of uniform distributed SiC particles can significantly improve the ultimate tensile strength and elongation to failure of the deposits. Calculation of apparent activation volume from tensile test results at different strain rates proved that incorporation of SiC nano-particles are responsible for stress-assisted activation of GB atoms mechanism that can significantly increase the plasticity. Nano-crystalline Ni–Co matrix showed a mixed mod behavior of ductile and brittle fracture whereas incorporation of SiC particles and increasing the strain rate promoted ductile fracture mode.
Lee, Y. I.; Shih, C. W.; Chang, W. C.; Chang, H. W.; Chen, Y. J.
2015-03-01
The inhomogeneity on texture, microstructure and magnetic properties of hot deformed (HD) disc shape R2Fe14B-typed magnets along radial and axial directions has been investigated. HD disc shape NdFeB magnet exhibits inhomogeneous texture, grain morphologies and magnetic properties not only along the radial direction but also along the axial direction. Higher magnetic properties can be found in the middle part of the HD magnet, due to the existence of larger volume fraction of plate-like Nd2Fe14B grains and the well c-axis alignment parallel to the pressing direction. In addition, particle-like and coarser grains are easily found not only in the bottom but also in the edge of the HD magnet, which may degrade the magnetic performance of the samples cut from those parts. Owing to the inhomogeneity of (00L) texture and grain morphologies along axial and radial directions, the optimal magnetic properties of Br = 12.7 kG, Hci = 5.1 kOe and (BH)max = 39 MGOe can be obtained only in the middle sample of HD magnet with slight polishing the top and bottom surfaces.
International Nuclear Information System (INIS)
Purpose: To evaluate the long-term mechanical behavior in vivo of expandable endobronchial wire stents, we imaged three different prostheses in the treatment of tracheobronchial disease. Methods: Six patients with bronchial stenoses (three benign, three malignant) underwent insertion of metallic stents. Two self-expandable Wallstents, two balloon-expandable tantalum Strecker stents and two self-expandable nitinol Accuflex stents were used. Measurements of deformation properties were performed during voluntary cough by means of fluoroscopy, at 1 month and 7-10 months after implantation. The procedures were videotaped, their images digitized and the narrowing of stent diameters calculated at intervals of 20 msec. Results: After stent implantation all patients improved with respect to ventilatory function. Radial stent narrowing during cough reached 53% (Wallstent), 59% (tantalum Strecker stent), and 52% (nitinol Accuflex stent) of the relaxed post-implantation diameter. Stent compression was more marked in benign compared with malignant stenoses. In the long term permanent deformation occurred with the tantalum Strecker stents; the other stents were unchanged. Conclusion: Endobronchial wire stents can be helpful in the treatment of major airway collapse and obstructing bronchial lesions. However, evidence of material fatigue as a possible effect of exposure to recurrent mechanical stress on the flexible mesh tube may limit their long-term use. This seems to be predominantly important in benign bronchial collapse
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.
International Nuclear Information System (INIS)
Preliminary tension has been studied for the effect of its degree on the mechanical characteristics and microstructure of steel 15Kh2MFA with ?0.2-540 and 950 MPa. Different mechanisms of steel failure are determined depending on the yield point level. At the first stage of plastic deformation of smooth specimens formation and growth of micorpores in both steels proceed in force direction. Then steel 15Kh2MFA (I) shows not only the longitudinal growth of pores but also the transversal growth as well as mutual coalescence, which is responsible for the pit fracture. Steel 15Kh2MFA (II) retains the longitudinal growth and coalescence of pores up to the formation of microcracks and longitudinal separation into layers at the stage preceeding the specimen complete failure. In this case grain-boundary quasi-brittle fracture is mainly observed
Oguri, Akira; Amaha, Shinichi; Nisikawa, Yunori; Hewson, A. C.; Tarucha, Seigo; Numata, Takahide
2010-03-01
We study transport through a triangular triple quantum dot (TTQD) connected to two noninteracting leads, using the numerical renormalization group. The system has been theoretically revealed to show a variety of Kondo effects depending on the electron filling of the triangle [1]. For instance, the SU(4) Kondo effect takes place at three-electron filling, and a two-stage Kondo screening of a high-spin S=1 Nagaoka state takes place at four-electron filling. Because of the enhanced freedom in the configurations, however, the large parameter space of the TTQD still has not been fully explored, especially for large deformations. We report the effects of the inhomogeneity in the inter-dot couplings and the level positions in a wide region of the filling. [1] T. Numata, Y. Nisikawa, A. Oguri, and A. C. Hewson: PRB 80, 155330 (2009).
Directory of Open Access Journals (Sweden)
Yurkova A.I.
2012-08-01
Full Text Available By using nanoindentation technique relationship between microstructure and mechanical parameters such as nanohardness Hh, plasticity characteristic, and Young’s modulus E were found to be dependent on the grain size of the bcc-Fe subjected to severe plastic deformation by friction (SPDF with argon atmosphere. Unlike fcc-metals in which the decreasing of grain size to 20 nm results in hardness growth accompanied by decreasing the plasticity, it was found the reverse effect in bcc-Fe, i.e. decreasing the grain size from 50 to 20 nm caused the decrease of hardness and increase of plasticity. Moreover, the decrease of Young’s modulus E with decreasing the grain size down to 20 nm was detected in nanoindentation experiments.
Energy Technology Data Exchange (ETDEWEB)
Stepanov, G.V., E-mail: gstepanov@mail.ru [Institute of Chemistry and Technology of Organoelement Compounds, Sh. Entuziastov 128, Moscow 111123 (Russian Federation); Chertovich, A.V. [Physics Department, Moscow State University, Moscow 119991 (Russian Federation); Kramarenko, E.Yu., E-mail: kram@polly.phys.msu.ru [Physics Department, Moscow State University, Moscow 119991 (Russian Federation)
2012-10-15
Viscoelastic and deformational behavior of soft magnetic elastomers with hard magnetic fillers under the influence of a magnetic field is studied by different experimental techniques. The magnetic elastomers used in this work were synthesized on the basis of silicone rubber filled with FeNdB particles and were magnetized in a field of 3 and 15 kOe. We have shown that due to high residual magnetization the materials demonstrate well pronounced non-elastic behavior already in the absence of any external magnetic field. In particular, in contrast to magnetic elastomers based on soft magnetic fillers their elastic modulus is strain-dependent. Under the influence of external magnetic field the storage and loss moduli of magnetic elastomers with hard magnetic filler can both increase and decrease tremendously.
Petrichenko, O; Erglis, K; C?bers, A; Plotniece, A; Pajuste, K; Béalle, G; Ménager, Ch; Dubois, E; Perzynski, R
2013-01-01
We synthesize giant magnetic liposomes by a reverse-phase evaporation method (REV) using a new self-assembling Cationic Pyridine Amphiphile (CPA) derived from 1,4-dihydropyridine as liposome-forming agent and a magnetic ferrofluid based on ?-Fe(2)O(3) nanoparticles. Having in view the potential interest of CPA in targeted transport by magnetic forces, the mechanical elastic properties of such bilayers are here directly investigated in vesicles loaded with magnetic nanoparticles. Bending elastic modulus K(b) ? 0.2 to 5k(B)T and pre-stress ? ? 3.2 to 12.10(-6) erg/cm(2) are deduced from the under-field deformations of the giant magnetic liposomes. The obtained K(b) values are discussed in terms of A. Wurgers's theory. PMID:23359032
International Nuclear Information System (INIS)
Magnetic properties of the grain oriented (GO) electrical steels are strongly affected by the stresses, both external and internal. The change is important even for the deformation resulting in stress level much lower than their yield limits. In this paper we present the results of investigation of the influence of compression and tension on the magnetoacoustic emission (MAE) signal properties. The experiment was performed with the help of bending machine in which the samples (0.3 mm thick, M140-30 S GO electrical steel) glued to the non-magnetic (austenitic steel) 8 mm thick bars were bent. The samples cut out in two directions (parallel and perpendicular to the rolling direction) were investigated. The elongation was measured directly with the help of tensometric bridge. Various parameters of the MAE signal, such as e.g. signal intensity and MAE peaks separation, have been examined. - Highlights: ? Magnetic properties of the GO electrical steels are strongly affected by stress. ? The non-destructive method of investigation of the ready-made components is needed. ? Magnetoacoustic emission is sensitive to stress-induced domain structure changes. ? Advanced signal analysis allows to determine the stress level in an unambiguous way.
Role of deformation on giant resonances within the QRPA approach and the Gogny force
Peru, S
2008-01-01
Fully consistent axially-symmetric-deformed Quasi-particle Random Phase Approximation (QRPA) calculations have been performed, in which the same Gogny D1S effective force has been used for both the Hartree-Fock-Bogolyubov mean field and the QRPA approaches. Giant resonances calculated in deformed $^{26-28}$Si and $^{22-24}$Mg nuclei as well as in the spherical $^{30}$Si and $^{28}$Mg isotopes are presented. Theoretical results for isovector-dipole and isoscalar monopole, quadrupole, and octupole responses are presented and the impact of the intrinsic nuclear deformation is discussed.
Measurements of octupole collectivity in Rn and Ra nuclei using Coulomb excitation
We propose to exploit the unique capability of HIE-ISOLDE to povide post-accelerated $^{221,222}$Rn and $^{222,226,228}$Ra ion beams for the study of octupole collectivity in these nuclei. We will measure E3 transition momnets in $^{222}$Rn and $^{222,226,228}$Ra in order to fully map out the variation in E3 strengh in the octupole mass region with Z$\\thicksim$88 and N$\\thicksim$134. This will validate model calculations that predict different behaviour as a function of N. We will also locate the position of the parity doublet partner of the ground state in $^{221}$Rn, in order to test the suitability of odd-A radon isotopes for EDM searches.
Mixed-symmetry octupole and hexadecapole excitations in the N=52 isotones
Hennig, A; Werner, V; Ahn, T; Anagnostatou, V; Cooper, N; Derya, V; Elvers, M; Endres, J; Goddard, P; Heinz, A; Huges, R O; Ilie, G; Mineva, M N; Petkov, P; Pickstone, S G; Pietralla, N; Radeck, D; Ross, T J; Savran, D; Zilges, A
2015-01-01
Background: Excitations with mixed proton-neutron symmetry have been previously observed in the $N=52$ isotones. Besides the well established quadrupole mixed-symmetry states (MSS), octupole and hexadecapole MSS have been recently proposed for the nuclei $^{92}$Zr and $^{94}$Mo. Purpose: The heaviest stable $N=52$ isotone $^{96}$Ru was investigated to study the evolution of octupole and hexadecapole MSS with increasing proton number. Methods: Two inelastic proton-scattering experiments on $^{96}$Ru were performed to extract branching ratios, multipole mixing ratios, and level lifetimes. From the combined data, absolute transition strengths were calculated. Results: Strong $M1$ transitions between the lowest-lying $3^-$ and $4^+$ states were observed, providing evidence for a one-phonon mixed-symmetry character of the $3^{(-)}_2$ and $4^+_2$ states. Conclusions: $sdg$-IBM-2 calculations were performed for $^{96}$Ru. The results are in excellent agreement with the experimental data, pointing out a one-phonon he...
Lower hybrid heating associated with mode conversion on the Wisconsin octupole
International Nuclear Information System (INIS)
This thesis addresses the following key issues in the lower hybrid frequency range: 1. What are the importent physics aspects of wave propagation and heating in an experimental situation. 2. How effective is plasma heating in the complex magnetic field configuration of the octupole. Experimental work is accomplished by launching 1-10ms pulses of up to 40kW of radio frequency power at 140MHz corresponding to the hot plasma lower hybrid resonance in the octupole. A diploe antenna which is moveable radially and is also rotatable couples wave power to the plasma. Coupling efficiencies greater than 95% are achieved by proper antenna placement near the edge of the plasma radial density profile
Multipole modes in deformed nuclei within the finite amplitude method
Kortelainen, M; Nazarewicz, W
2015-01-01
Background: To access selected excited states of nuclei, within the framework of nuclear density functional theory, the quasiparticle random phase approximation (QRPA) is commonly used. Purpose: We present a computationally efficient, fully self-consistent framework to compute the QRPA transition strength function of an arbitrary multipole operator in axially-deformed superfluid nuclei. Methods: The method is based on the finite amplitude method (FAM) QRPA, allowing fast iterative solution of QRPA equations. A numerical implementation of the FAM-QRPA solver module has been carried out for deformed nuclei. Results: The practical feasibility of the deformed FAM module has been demonstrated. In particular, we calculate the quadrupole and octupole strength in a heavy deformed nucleus $^{240}$Pu, without any truncations in the quasiparticle space. To demonstrate the capability to calculate individual QRPA modes, we also compute low-lying negative-parity collective states in $^{154}$Sm. Conclusions: The new FAM imp...
Ozgowicz, W.; A. Kurc; M. Kciuk
2010-01-01
Purpose: The aim of the paper was to determine the effect of deformation-induced martensite on the microstructure, mechanical properties and corrosion resistance of X5CrNi18-8 austenitic steel.Design/methodology/approach: The investigations included observations of the microstructure on a light microscope, researches of mechanical properties in a static tensile test, microhardness measurements made by Vickers’s method and corrosion resistance test examined using weight method. The analysis of...
International Nuclear Information System (INIS)
Mechanical properties of nuclear fuel are a complex problem, involving many coupled mechanisms occurring at different length scales. We used Molecular Dynamics models to bring some light on some of these mechanisms at the atomic scale. We devised a procedure to calculate transition pathways between some UO2 polymorphs, and then carried out dynamics simulations of these transitions. We confirmed the stability of the cotunnite structure at high pressure using various empirical potentials, the fluorite structure being the most stable at room pressure. Moreover, we showed a reconstructive phase transition between the fluorite and cotunnite structures. We also showed the importance of the major deformation axis on the kind of transition that occur under tensile conditions. Depending on the loading direction, a scrutinyite or rutile phase can appear. We then calculated the elastic behaviour of UO2 using different potentials. The relative agreement between them was used to produce a set of parameters to be used as input in mesoscale models. We also simulated crack propagation in UO2 single crystals. These simulations showed secondary phases nucleation at crack tips, and hinted at the importance thereof on crack propagation at higher length-scales. We then described some properties of edge dislocations in UO2. The core structures were compared for various glide planes. The critical resolved shear stress was calculated for temperatures up to 2000 K. These calculations showed a link between lattice disorder at the dislocations core and the dislocations mobility. (author)
Murashkin, M. Yu.; Kil'Mametov, A. R.; Valiev, R. Z.
2008-07-01
The effect of an ultrafine-grained (UFG) structure formed in an aluminum alloy 1570 using severe plastic deformation by high-pressure torsion (HPT) at room temperature and at temperatures of 100 and 200°C on the mechanical properties (strength and plasticity) has been investigated. The specific features of the UFG states obtained have been studied by transmission electron microscopy and X-ray diffraction analysis. The main regularities of changes in the structure characteristics of the alloy (the average grain size, size of coherent domains, magnitudes of microdeformations of the crystal lattice, dislocation density, and the lattice parameter) have been established depending on the temperature of the HPT treatment. The mechanical properties of the alloy after HPT have been estimated from the results of microhardness measurements and mechanical tests for tension. It has been established that after HPT performed at room temperature, the UFG alloy demonstrates an ultimately high level of strength (the microhardness, offset yield strength, and ultimate strength reach 2300, 905, and 950 MPa, respectively) and a marked plasticity (the relative elongation at fracture was 4.7%). The HPT treatment performed at higher temperatures insignificantly reduces the strength characteristics of the UFG material but leads to a substantial drop in its plasticity. This unusual mechanical behavior of the UFG alloy is discussed based on an analysis of the results of structural investigations.
Energy Technology Data Exchange (ETDEWEB)
Mathez, E A; Roberts, J J; Duba, A G; Kronenberg, A K; Karner, S L
2008-05-16
To investigate potential mechanisms for geoelectric phenomena accompanying earthquakes, we have deformed hollow cylinders of Sioux quartzite to failure in the presence of carbonaceous pore fluids and investigated the resulting changes in electrical conductivity and carbon distribution. Samples were loaded at room temperature or 400 C by a hydrostatic pressure at their outer diameter, increasing pressure at a constant rate to {approx}290 MPa. Pore fluids consisted of pure CO, CO{sub 2}, CH{sub 4} and a 1:1 mixture of CO{sub 2} and CH{sub 4}, each with pore pressures of 2.0 to 4.1 MPa. Failure occurred by the formation of mode II shear fractures transecting the hollow cylinder walls. Radial resistivities of the cylinders fell to 2.9 to 3.1 M{Omega}-m for CO tests and 15.2 to 16.5 M{Omega}-m for CO{sub 2}:CH{sub 4} tests, compared with >23 M{Omega}-m for dry, undeformed cylinders. Carbonaceous fluids had no discernable influence on rock strength. Based on mapping using electron microprobe techniques, carbon occurs preferentially as quasi-continuous films on newly-formed fracture surfaces, but these films are absent from pre-existing surfaces in those same experiments. The observations support the hypothesis that electrical conductivity of rocks is enhanced by the deposition of carbon on fracture surfaces and imply that electrical properties may change in direct response to brittle deformation. They also suggest that the carbon films formed nearly instantaneously as the cracks formed. Carbon film deposition may accompany the development of microfracture arrays prior to and during fault rupture and thus may be capable of explaining precursory and coseismic geoelectric phenomena.
International Nuclear Information System (INIS)
An experiment using the Eurogam phase II ?-ray spectrometer confirms the existence of an excited superdeformed (SD) band in 190Hg and its very unusual decay into the lowest SD band over 3--4 transitions. The energies of the transitions linking the two SD bands have been firmly established, and their angular distributions are consistent with a dipole character. Comparisons with calculations using random-phase approximation indicate that the excited SD band can be interpreted as an octupole-vibrational structure
Microscopic investigation of octupole modes of oscillation via analyzing power measurements
International Nuclear Information System (INIS)
Measurements of the analyzing power in the two-nucleon transfer reactions 70Ge, 72Ge (t,p) have been carried out. This is a region where a shape transition has been previously proposed. Contrary to recent (p,t) results, no strong interference effects between direct and two step processes leading to the 21+ states have been observed. However, a marked difference has been revealed for the 31- octupole transition. A microscopic interpretation of this effect is proposed
Evidence for high energy giant octupole resonance in medium and heavy mass nuclei
International Nuclear Information System (INIS)
Inelastic scattering of 3He-particles at 110 - 140 MeV on medium and heavy mass nuclei reveals the presence of a new resonance at Ex -- 118A sup(1/3) MeV with a width of about 7 MeV. Angular distribution of the resonance prefers an L = 3 transition and an octupole energy-weighted sum-rule fraction of 47 - 95% is exhausted. (author)
Mechanical properties of severely deformed ZA-27 alloy using equal channel angular extrusion
Energy Technology Data Exchange (ETDEWEB)
Purcek, G.; Altan, B.S.; Miskioglu, I.; Patil, A.
2005-09-15
As cast ZA-27 alloy was subjected to equal channel angular extrusion (ECAE) with up to four passes using three different processing routes, and its mechanical properties (strength, hardness, ductility and extrusion load) were evaluated. The changes in the microstructure were also investigated. The ECAE was found to be quite effective in enhancing the mechanical properties of ZA-27 alloy. The strength and hardness of the alloys increased after the first ECAE pass followed by a gradual decrease with further passes for all processing routes. The elongation to failure, however, exceptionally increased with increase in the number of passes for all processing routes. Combined high strength and good ductility were obtained in the alloy after the first pass. The strength and maximum extrusion load showed similar trends with the number of passes for all processing routes. (author)
On the relationship between large-deformation properties of wheat flour dough and baking quality
Sliwinski, E.L.; Kolster, P.; Vliet, T.
2004-01-01
Baking performance for bread and puff pastry was tested for Six European and two Canadian wheat cultivars and related to the rheological and fracture properties in uniaxial extension of optimally mixed flour-water doughs and doughs to which a mix of bakery additives was added. Extensive baking tests were performed as a function of water addition for puff pastry and as a function of water addition and mixing time for bread. For optimum baking performance, puff pastry doughs required lower wate...
Dong, C.(Nankai university, Tianjin, 300071, People's Republic of China); Chadwick, R S; Schechter, A.N.
1992-01-01
The rheological properties of normal erythrocytes appear to be largely determined by those of the red cell membrane. In sickle cell disease, the intracellular polymerization of sickle hemoglobin upon deoxygenation leads to a marked increase in intracellular viscosity and elastic stiffness as well as having indirect effects on the cell membrane. To estimate the components of abnormal cell rheology due to the polymerization process and that due to the membrane abnormalities, we have developed a...
Annealing behaviour and mechanical properties of severely deformed interstitial free steel
International Nuclear Information System (INIS)
Highlights: ? Microstructure and micro-texture evolution indicates continuous recrystallisation. ? HAGBs decrease from ?80 to ?40% due to texture clustering and orientation pinning. ? Characterisation of correlation between tensile and shear punch tests. ? Tensile behaviour evolves from stress drop to continuous yielding a work hardening. - Abstract: The evolution of microstructure, micro-texture and mechanical properties during isothermal annealing of an ultrafine grained interstitial free (IF) steel processed by Equal Channel Angular Pressing (ECAP) followed by 95% cold rolling (CR) was studied. Microstructure and micro-texture changes were characterised by Electron Back-Scattering Diffraction while mechanical properties were assessed by shear punch and uniaxial tensile testing. During annealing, homogeneous coarsening via continuous recrystallisation is accompanied by the retention of a sharp ?-fibre rolling texture and a decrease in area fraction of high angle grain boundaries from ?80% to ?40% due to texture clustering and orientation pinning. Failure during uniaxial tension occurred without post-necking elongation after CR. Upon annealing, an evolution from stress-drop soon after yielding to a return to continuous yielding and increased work hardening was observed. Good agreement is found between experimental and estimated strengths and total elongations derived from SPT and tensile data. Tensile characteristics and mechanical properties depend on both, grain size and area fraction of HAGBs.
Annealing behaviour and mechanical properties of severely deformed interstitial free steel
Energy Technology Data Exchange (ETDEWEB)
Gazder, Azdiar A. [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, New South Wales 2522 (Australia); Hazra, Sujoy S., E-mail: sujoy.hazra@gmail.com [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, New South Wales 2522 (Australia); Pereloma, Elena V. [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, New South Wales 2522 (Australia)
2011-12-15
Highlights: Black-Right-Pointing-Pointer Microstructure and micro-texture evolution indicates continuous recrystallisation. Black-Right-Pointing-Pointer HAGBs decrease from {approx}80 to {approx}40% due to texture clustering and orientation pinning. Black-Right-Pointing-Pointer Characterisation of correlation between tensile and shear punch tests. Black-Right-Pointing-Pointer Tensile behaviour evolves from stress drop to continuous yielding a work hardening. - Abstract: The evolution of microstructure, micro-texture and mechanical properties during isothermal annealing of an ultrafine grained interstitial free (IF) steel processed by Equal Channel Angular Pressing (ECAP) followed by 95% cold rolling (CR) was studied. Microstructure and micro-texture changes were characterised by Electron Back-Scattering Diffraction while mechanical properties were assessed by shear punch and uniaxial tensile testing. During annealing, homogeneous coarsening via continuous recrystallisation is accompanied by the retention of a sharp {alpha}-fibre rolling texture and a decrease in area fraction of high angle grain boundaries from {approx}80% to {approx}40% due to texture clustering and orientation pinning. Failure during uniaxial tension occurred without post-necking elongation after CR. Upon annealing, an evolution from stress-drop soon after yielding to a return to continuous yielding and increased work hardening was observed. Good agreement is found between experimental and estimated strengths and total elongations derived from SPT and tensile data. Tensile characteristics and mechanical properties depend on both, grain size and area fraction of HAGBs.
Kaisar, Khan Hasib
Nanocrystalline Al-Mg alloys are being considered for light weight transportation applications because they possess significantly higher strength than the conventional coarse grained alloys. Failure strengths higher than 1000 MPa have been reported for Al-5083 alloy at New Mexico Tech, which are almost double the strength of commercial precipitation strengthened Al-alloys. Unfortunately, the ductility tends to exhibit inverse relationship to strength and therefore there is a need to find ways to increase the ductility while maintaining high strength. In this work, we utilize a near Al-5083 alloy that was cryomilled for 24 hours in liquid nitrogen environment and consolidated by vacuum hot-pressing. The as-atomized Al-Mg powder was especially fabricated to minimize undesired impurity content to prevent premature fracture from intermetallic particles. It turned out that the final composition was slightly lower in Mn and Mg content and so the alloy is better designated as a near Al-5083 alloy. The as-vacuum hot pressed material had poor ductility because of inadequate prior-particle bonding, and therefore was subjected to deformation processing using low strain-rate extrusion at elevated temperatures. Both the strain-rate and temperature of extrusion were varied in an effort to obtain a good combination of tensile strength and ductility. In addition, the samples were annealed following extrusion in order to reduce residual stresses. The microstructure of extruded samples were characterized using a combination of electron microscope and X-ray diffraction techniques, and revealed a multi-scale morphology that could be binned into three different sizes of grains: i) those less than 100 nm that were analyzed using the X-ray based Williamson-Hall technique and transmission electron microscopy (TEM), ii) grain sizes in the 100-300 nm regime that were best revealed using TEM and scanning electron microscope (SEM) based electron-backscatter diffraction (EBSD) techniques, and, iii) elongated larger grains with lengths in the range 3 to 7 ?m that were observed using EBSD. Room temperature tensile tests with small tensile samples indicated that ultimate strengths in the range 740-760 MPa and elongation to failure better than 2.5%. These data could be produced reproducibly following extrusion at 400 C at an average strain rate of 0.05/sec, and fractography revealed a rough topography with large pull out regions that consisted of typical ductile dimple void growth at the 200-500 nm scale, while in other regions the dimples were very shallow that would suggest failure with little energy loss likely in regions of nanograins less than 100 nm. The combination of strength and ductility in the material are some of the best that have been reported for Al-5083 alloys, and likely a result of the multi-scale microstructure resulting from processing through the cryomilling and extrusion plus annealing procedures.
Tosti, Fabio; Benedetto, Andrea; Bianchini Ciampoli, Luca; Adabi, Saba; Pajewski, Lara
2015-04-01
The great flexibility of ground-penetrating radar has led to consider worldwide this instrument as an effective and efficient geophysical tool in several fields of application. As far as pavement engineering is concerned, ground-penetrating radar is employed in a wide range of applications, including physical and geometrical evaluation of road pavements. Conversely, the mechanical characterization of pavements is generally inferred through traditional (e.g., plate bearing test method) or advanced non-destructive techniques (e.g., falling weight deflectometer). Nevertheless, measurements performed using these methods, inevitably turn out to be both much more time-consuming and low-significant whether compared with ground-penetrating radar's potentials. In such a framework, a mechanical evaluation directly coming from electromagnetic inspections could represent a real breakthrough in the field of road assets management. With this purpose, a ground-penetrating radar system with 600 MHz and 1600 MHz center frequencies of investigation and ground-coupled antennas was employed to survey a 4m×30m flexible pavement test site. The test area was marked by a regular grid mesh of 836 nodes, respectively spaced by a distance of 0.40 m alongside the horizontal and vertical axes. At each node, the elastic modulus was measured using a light falling weight deflectometer. Data processing has provided to reconstruct a 3-D matrix of amplitudes for the surveyed area, considering a depth of around 300 mm, in accord to the influence domain of the light falling weight deflectometer. On the other hand, deflectometric data were employed for both calibration and validation of a semi-empirical model by relating the amplitude of signal reflections through the media along fixed depths within the depth domain considered, and the Young's modulus of the pavement at the evaluated point. This statistically-based model is aimed at continuously taking into account alongside the depth of investigation, of both the different strength provision of each layer composing the hot mix asphalt pavement structure, and of the attenuation occurring to electromagnetic waves during their in-depth propagation. Promising results are achieved by matching modelled and measured elastic modulus data. This continuous statistically-based model enables to consider the whole set of information related to each single depth, in order to provide a more comprehensive prediction of the strength and deformation behavior of such a complex multi-layered medium. Amongst some further developments to be tackled in the near future, a model improvement could be reached through laboratory activities under controlled conditions and by adopting several frequency bandwidths suited for purposes. In addition, the perspective to compare electromagnetic data with mechanical measurements retrieved continuously, i.e., by means of specifically equipped lorries, could pave the way to considerable enhancements in this field of research. Acknowledgements - This work has benefited from networking activities carried out within the EU funded COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar".
International Nuclear Information System (INIS)
In this report, the rock mechanics parameters of fractures and brittle deformation zones have been estimated in the vicinity of the ONKALO underground research facility at the Olkiluoto site, western Finland. This report is an extension of two previously published reports describing the geometrical and mechanical properties of the fractures and brittle deformation zones based on ONKALO tunnel mapping from tunnel chainages 0-2400 m (Kuula 2010) and 2400-4390 m (Moenkkoenen et al. 2012). This updated report makes use of mapping data from tunnel chainage 4390-4990 m, including the technical rooms located at the -420 m below the sea level. Analysis of the technical rooms is carried out by dividing the premises according to depth into three sections: the demonstration tunnel level, the technical rooms level and the -457 level. The division is executed in order to define the fracture properties in separate areas and to compare the properties with other technical rooms levels. Drillhole data from holes OL-KR1...OL-KR57 is also examined. This report ends the series of three parameterization reports. The defined rock mechanics parameters of the fractures are based on the rock engineering classification quality index, Q', which incorporates the RQD, Jn, Jr and Ja values. The friction angle of the fracture surfaces is estimated from the Jr and Ja numbers. No new data from laboratory joint shear and normal tests was available at the time of the report. The fracture wall compressive strength (JCS) data is available from the chainage range 1280-2400 m. New data for fracture wall compressive strength is not available although new Schmidt hammer measurements were performed in order to obtain the ratio of the intact rock mass vs. an intact brittle deformation zone. Estimation of the mechanical properties of the 23 brittle deformation zones (BDZ) is based on the mapped Q' value, which is converted into the GSI value in order to estimate the strength and deformability properties. Components of the mapped Q' values are either from the ONKALO or the drill cores depending on the availability of intersections. The location and size of the brittle deformation zones are based on the latest interpretation (Aaltonen et al. expected in 2014). New laboratory data for the intact rock strength of the brittle deformation zones is not available. (orig.)
Directory of Open Access Journals (Sweden)
Jab?o?ska M.B.
2014-10-01
Full Text Available Since few years many research centres conducting research on the development of high-manganese steels for manufacturing of parts for automotive and railway industry. Some of these steels belong to the group of AHS possessing together with high strength a great plastic elongation, and an ideal uniform work hardening behavior. The article presents the dynamic mechanical properties of two types of high manganese austenitic steel with using a flywheel machine at room temperature with strain rates between 5×102÷3.5×103s?–1. It was found that the both studied steels exhibit a high sensitivity Rm to the strain rate. With increasing the strain rate from 5×102 to 3.5×103s?–1 the hardening dominates the process. The fracture analysis indicate that after dynamic test both steel is characterized by ductile fracture surfaces which indicate good plasticity of investigated steels.
Terada, Daisuke; Kaneda, Yoma; Horita, Zenji; Matsuda, Kenji; Hirosawa, Shoichi; Tsuji, Nobuhiro
2014-08-01
In order to clarify the aging behavior in ultrafine grained (UFG) Al alloys, a commercial Al-Mg-Si alloy was severely deformed by accumulative roll-bonding (ARB) process and subsequently aged at 100°C or 170°C. The age-hardening behavior and microstructure change during aging were investigated. At 170 °C, age-hardening was observed in solution treated (ST) specimens, but solution-treated and ARB-processed specimens were not hardened by aging. On the other hand, the hardness of the both ST specimen and ARB-processed specimen increased by aging at 100°C. From TEM observation, it was found that the ARB- processed specimen had an ultrafine lamellar boundary structure and the structure was kept during aging at 170°C and 100°C. In the ST specimen aged at 170°C, fine precipitates were observed within coarse grains. In the specimen ARB-processed and subsequently aged at 170°C, coarser precipitates were observed within ultrafine grains and on grain boundaries. It was considered that the reason why the hardness of the specimens ARB-processed and subsequently aged did not increase was coarsening of precipitates. In the specimens aged at 100°C, obvious precipitates were not observed, but clusters Mg and Si seemed to form during the aging, leading to the increase in the hardness of the specimen. From the results, it was suggested that aging at low temperatures could improve mechanical properties of Al alloys through combining grain refinement and precipitation hardening.
Poudyal, Narayan; Xia, Weixing; Yue, Ming; Ping Liu, J.
2014-05-01
We report bulk SmCo3/?-Fe nanocomposite magnets prepared via high energy ball milling and warm compaction. The evolution of structure and magnetic properties with soft phase fraction have been systematically studied. Microstructural studies revealed that grain size of the nanocomposite magnets can be controlled below 20 nm with a homogeneous distribution of ?-Fe phase in the matrix of hard magnetic SmCo3 phase after severe plastic deformation. The refinement of the hard and soft phases morphology in nanoscale leads to effective inter-phase exchange coupling that gives rise to single-phase-like demagnetization behavior with enhanced remanence and maximum energy product (BH)max. The (BH)max up to 13.5 MGOe in the isotropic SmCo3/?-Fe nanocomposites with 25 wt. % of the soft phase has been obtained. Magnetic characterization at elevated temperatures shows that the nanocomposite SmCo3/?-Fe magnets have improved energy product compared to the single-phase SmCo3 magnets.
Lee, Deuk-Hee; Lee, Jae-Uk; Jung, Sung-Jin; Baek, Seung-Hyub; Kim, Ju-Heon; Kim, Dong-Ik; Hyun, Dow-Bin; Kim, Jin-Sang
2014-06-01
In this work, p-type 20%Bi2Te3-80%Sb2Te3 bulk thermoelectric (TE) materials were prepared by mechanical deformation (MD) of pre-melted ingot and by mechanical alloying (MA) of elemental Bi, Sb, and Te granules followed by cold-pressing. The dependence on annealing time of changes of microstructure and TE properties of the prepared samples, including Seebeck coefficient, electrical resistivity, thermal conductivity, and figure-of-merit, was investigated. For both samples, saturation of the Seebeck coefficient and electrical resistivity were observed after annealing for 1 h at 380°C. It is suggested that energy stored in samples prepared by both MA and MD facilitated their recrystallization within short annealing times. The 20%Bi2Te3-80%Sb2Te3 sample prepared by MA followed by heat treatment had higher a Seebeck coefficient and electrical resistivity than specimens fabricated by MD. Maximum figures-of-merit of 3.00 × 10-3/K and 2.85 × 10-3/K were achieved for samples prepared by MA and MD, respectively.
Barbadikar, Dipika R.; Ballal, A. R.; Peshwe, D. R.; Mathew, M. D.
2015-08-01
Ball indentation (BI) technique has been effectively used to evaluate the tensile properties with minimal volume of material. In the present investigation, BI test carried out on P92 steel (9Cr-0.5Mo-1.8W), using 0.76 mm diameter silicon nitride ball indenter was modeled using finite element (FE) method and analyzed. The effect of test temperature [300 K and 923 K (27 °C and 650 °C)], tempering temperature [1013 K, 1033 K, and 1053 K (740 °C, 760 °C, and 780 °C)], and coefficient of friction of steel (0.0 to 0.5) on the tensile strength and material pile-up was investigated. The stress and strain distributions underneath the indenter and along the top elements of the model have been studied to understand the deformation behavior. The tensile strength was found to decrease with increase in tempering and test temperatures. The increased pile-up around the indentation was attributed to the decrease in strain hardening exponent ( n) with increase in the test temperature. The pile-up height determined from profilometry studies and FE analysis as well as the load depth curve from BI and FE analysis was in agreement. The maximum strain location below the indentation changes with the test temperature. Stress-strain curves obtained by conventional tensile, BI test, and representative stress-strain concepts of FE model were found exactly matching.
Influence of cementation on the deformation properties of bentonite/quartz buffer substance
International Nuclear Information System (INIS)
Cementation, e.g.precipitation of crystalline or solid amorphous inorganic substance between individual grains, greatly affects the mechanical properties of fine-grained soils. As concerns the buffer mass with the composition suggested (10 weight percent bentonite and 90% quartz particles) the intergranular contact pressure between the quartz particles will not be able to cause 'pressure solution'. Also, the other possible cementation effects will be negligible with the exception of the process which leads to precipitation of SiO2 dissolved from quartz particles and enriched in the interstitial pore space. This process and its consequences will be treated in this report. The nature of silica solution and precipitation is not known in detail. The chemical environment, temperature, pH and ion strength are known to be controlling factors which combine to make possible alternating solution and precipitation of silica. However, as shown by the case survey and the presented theoretical treatment the amount of precipitated SiO2 will not be able to produce a brittle behaviour of the buffer mass even after thousands of years
Peña, Juan A; Martínez, Miguel A; Peña, Estefanía
2015-10-01
In this paper we hypothesize that the layer-separated residual stresses and mechanical properties of layer-separated thoracic aorta arteries may be dependent on arterial location of the vessel. To demonstrate any possible position differences, we measured the axial pre-stretch and opening angle and performed uniaxial and biaxial tests under physiological loads to study the mechanical behavior of both intact and layer-separated porcine aortic samples taken from thoracic region. In addition, we also provided constitutive parameters for each layer that can be used by biomedical engineers for investigating better therapies and developing artery-specific devices. We found that the opening angle for whole artery and adventitia layer are smaller and intima greater for proximal segments than for the distal thoracic ones. For the axial pre-stretch, our results showed significant increased values of the stretch ratios with location. We found that lower thoracic samples are stiffer than upper ones with the most important differences corresponding to those between the proximal and distal behaviors in the circumferential direction. The anisotropy represented by the different circumferential and longitudinal response is more remarkable in lower thoracic aorta. Finally, adventitia and intima samples present a tendency to be stiffer and more isotropic than the corresponding media samples in both directions for upper thoracic aorta and to be more anisotropic for lower thoracic aorta. PMID:26103440
International Nuclear Information System (INIS)
In this report, the rock mechanics parameters of fractures and brittle deformation zones in the vicinity of the ONKALO area have been estimated, the analysed data being from the ONKALO tunnel over the chainage range 0-2400 m. Some analysis has also been made based on core logging data from the drillholes OL-KR1-OL-KR40. At this stage, the main objective of the work is to obtain preliminary parameters for the rock mechanics simulations and the rock mechanics design. In this report, the rock mechanics parameters of the fractures are mainly associated with the rock engineering classification quality index, Q, which incorporates the RQD, Jn, Jr and Ja values. The friction angle of the fracture surfaces is estimated from the Jr and Ja numbers. The fracture wall compressive strength (JCS) has been systematically estimated for the chainage range 1280-2400 m using Schmidt hammer tests. So far, only a few laboratory direct shear tests have been conducted on fracture samples. Estimation of the mechanics properties of the brittle deformation zones (BDZ) is based on the mapped Q value, which is transformed to the GSI value in order to estimate strength and deformability properties. A component of the mapped Q values is from the ONKALO and another component is from the drill cores. The intact rock strength of the brittle deformation zones has been evaluated using Schmidt hammer tests. (orig.)
Izotov, V. I.; Pozdnyakov, V. A.; Luk'yanenko, E. V.; Usanova, O. Yu.; Filippov, G. A.
2007-05-01
Specific features of plastic deformation and tensile failure of a plain carbon ( C = 0.62%) pearlitic-ferritic steel with various pearlite fineness have been investigated. It is shown that the steels with coarse lamellar pearlite and fine lamellar pearlite have similar strain-hardening coefficients, but the relative elongation of the former steel is higher. Deformation results in a uniform dislocation distribution in the fine pearlite and in the formation of a cellular substructure in the coarse pearlite. It is established that the fine pearlite undergoes plastic deformation and ductile failure as a single structure, while the coarse pearlite exhibits a structure discontinuity upon deformation. A model of microplastic pearlite deformation and the initial stage of macroplastic pearlite deformation is proposed. It is established that the strain-hardening coefficient of pearlite at the initial deformation stage does not depend on its dispersity. A size effect, which manifests itself in the dependence of the dislocation structure formed in the ferrite interlayers on their thickness, is shown to be characteristic of pearlite deformation.
International Nuclear Information System (INIS)
Seven-filament MgB2/Fe wires and tapes were made by in situ processing using hydrostatic extrusion, rolling and drawing. Microhardness measurements have shown that the density of as-deformed cores reflects the applied deformation and follows the iron sheath hardness. The filament size was reduced from 245 ?m down to 19 ?m by rolling and the critical current densities of samples with different core sizes and deformation routes were compared. The highest current density was measured for the tape deformed by two-axial rolling and a filament size of 60 ?m. Thinner filaments show lower Jc values due to hard inclusions present in low-purity boron powder (boron oxide), which reduce the transport current substantially. The obtained results show that a proper combination of extrusion and rolling deformations leads to high filament density in wires and tapes, which results in high transport current density
Kovác, P.; Hušek, I.; Pachla, W.; Kulczyk, M.
2007-07-01
Seven-filament MgB2/Fe wires and tapes were made by in situ processing using hydrostatic extrusion, rolling and drawing. Microhardness measurements have shown that the density of as-deformed cores reflects the applied deformation and follows the iron sheath hardness. The filament size was reduced from 245 µm down to 19 µm by rolling and the critical current densities of samples with different core sizes and deformation routes were compared. The highest current density was measured for the tape deformed by two-axial rolling and a filament size of 60 µm. Thinner filaments show lower Jc values due to hard inclusions present in low-purity boron powder (boron oxide), which reduce the transport current substantially. The obtained results show that a proper combination of extrusion and rolling deformations leads to high filament density in wires and tapes, which results in high transport current density.
International Nuclear Information System (INIS)
A new approach to the estimation of grain boundary contribution to formation of metal and alloy properties if proposed. The metal, both deformed and annealed, is considered as a self-organized system. Dissipative structures grain boundaries included exist in the material in initial undeformed state. Evaluation technique for interface induced stresses is suggested. Possible reasons for serrated yielding are discussed. Comparison of calculated and experimental data is made for nickel and austenitic steel. 16 refs., 2 figs
Directory of Open Access Journals (Sweden)
W. Ozgowicz
2010-05-01
Full Text Available Purpose: The aim of the paper was to determine the effect of deformation-induced martensite on the microstructure, mechanical properties and corrosion resistance of X5CrNi18-8 austenitic steel.Design/methodology/approach: The investigations included observations of the microstructure on a light microscope, researches of mechanical properties in a static tensile test, microhardness measurements made by Vickers’s method and corrosion resistance test examined using weight method. The analysis of the phase composition was carried out on the basis of X-ray researches. The amount of martensite ?’ in the obtained microstructures was investigated with ferritescope magnetic tester. The observations of the surface morphology after corrosive tests were carried out using Scanning Electron Microscope. The scope of this study was to achieve the correlations between the mechanical, corrosion and structural properties of cold rolled stainless steel.Findings: Plastic deformation in a cold working of austenitic stainless steel induced in its structure martensitic transformation ? ? ?’. The occurrence of martensite ?’ in the investigated steel structure has an essential meaning in manufacturing process of forming sheet-metals from austenitic steel.Research limitations/implications: The X-ray phase analysis in particular permitted to disclose and identify the main phases on the structure of the investigated steel after its deformation within the range 10 - 70%. The results of the ferritescope measurements allowed determining the proportional part of ?` phases in the structure of investigated steel in the examined range of cold plastic deformation. The microscope observations of the surface samples subjected to corrosion resistance test in 30 wt% H2SO4 solutions permitted to evaluate kinds and the rate of corrosion damages.Originality/value: A wide range of practical applications of 18/8 steel sheets is warranted by both their high corrosion resistance and high plastic properties.
Effect of hot deformation on texture and magnetic properties of Sm-Co and Pr-Co alloys
Energy Technology Data Exchange (ETDEWEB)
Gabay, A.M., E-mail: gabay@physics.udel.edu [Department of Physics and Astronomy, University of Delaware, 217 Sharp Lab, Newark, DE 19716 (United States); Li, W.F.; Hadjipanayis, G.C. [Department of Physics and Astronomy, University of Delaware, 217 Sharp Lab, Newark, DE 19716 (United States)
2011-10-15
Nanocrystalline PrCo{sub 5}, SmCo{sub 5} and Sm{sub 2}(Co,Fe,Mn){sub 17} alloys were subjected to a high-degree plastic deformation at 950 deg. C with the height reduction ranging from 70% to 95%. With increasing degree of deformation, the PrCo{sub 5} and SmCo{sub 5} magnets showed improvement of the deformation-induced [0 0 1] texture. The PrCo{sub 5} alloys, known to develop a superior texture at the lower degrees of deformation, showed only modest improvement and their magnetic performance was undermined by a low coercivity. The SmCo{sub 5} alloys had their texture markedly enhanced and, after height reduction by 94.5%, they exhibited a remanence of 8.6 kG, maximum energy product of 18 MGOe and an intrinsic coercivity of 22.8 kOe. No induced texture was found in the alloys based on the Sm{sub 2}Co{sub 17} structure. The microstructures of the hot-deformed alloys were studied with a transmission electron microscopy, and possible mechanisms of the texture development in the RCo{sub 5} alloys (R=Pr, Sm) are briefly discussed. - Highlights: > The effects high-degree deformation were compared for three rare earth-cobalt alloys. > SmCo{sub 5} alloys benefit most from deformation exceeding 90%. > High-degree deformation slightly improves texture of PrCo{sub 5} but damages the coercivity. > Even the high-degree deformation does not induce texture in alloys based on Sm{sub 2}Co{sub 17}.
Energy Technology Data Exchange (ETDEWEB)
Louis, L.
2003-10-15
From diagenesis to tectonic stress induced deformation, rock microstructures always present some anisotropy associated with a preferential orientation, shape or spatial arrangement of its constituents. Considering the consequences anisotropy has on directional transport properties and compliance, as the geological history it carries, this approach has received a particular attention in numerous works. In this work, the microstructural features of various sedimentary rocks were investigated through direct observations and laboratory measurements in naturally deformed and undeformed blocks, samples being considered as effective media. All investigated samples were found to be anisotropic with respect to the physical properties we measured (i.e. ultrasonic P-wave velocity, magnetic susceptibility, electrical conductivity). Considering that P-wave velocities can be described by a second order tensor, we applied to the velocity data the same inversion procedure as the one routinely used in magnetic studies, which provided an efficient tool to estimate and compare these 3D anisotropies with respect to the original sample geographical position. In each case, we tried to identify as thoroughly as possible the microstructural source of the observed anisotropies, first by the mean of existing models, then through direct observations (optic and electronic microscopy). Depending on the rock investigated, anisotropy was found to be controlled by pore shape, intergranular contact distribution, preferentially oriented microcracks interacting with compaction pattern or pressure solution cleavages interacting with each other. The net result of this work is that P-wave velocity anisotropy can express the interaction between different microstructural features as well as their evolution during deformation. (author)
High-power ion-cyclotron-resonance heating in the Wisconsin Levitated Octupole
International Nuclear Information System (INIS)
Ion cyclotron resonance heating has been investigated, both experimentally and theoretically, on the Wisconsin Levitated Octupole. Heating of both ions and electrons has been observed. Typically, a two component ion energy distribution is produced (300 eV and 50 eV) with the application of 500 kW of rf power into a 5 x 1012 cm-3 density plasma. Power is coupled to the plasma with an antenna that also serves as the inductor of an oscillator tank circuit. The oscillator is tunable from 1 to 3 MHz and can be applied for periods up to 10 msec. The experiments were performed with hydrogen, gun injected plasmas
Electric-dipole transitions and octupole softness in odd-A rare-earth nuclei
International Nuclear Information System (INIS)
It is found that B(E1) values calculated by using a model, in which one quasiparticle is coupled to a rotor, are more than an order of magnitude too small compared with measured B(E1) values in low-energy transitions observed in the yrast spectroscopy of odd-A rare-earth nuclei. Thus, the measured B(E1) values are analyzed by introducing the parameters which effectively take into account the octupole softness. An estimate of the parameters based on a microscopic model is made, and a discrepancy between the estimated values and the values necessary for reproducing data is found. (au)
THE EFFECT OF SUPERPLASTIC DEFORMATION ON THE TENSILE AND FATIGUE PROPERTIES OF Al-Li (8090) ALLOY
Mcdarmaid, D.; Shakesheff, A.
1987-01-01
Superplastic deformation of the new generation of aerospace aluminium-lithium alloys has generated considerable interest in the aerospace industry not only with the potential savings in component weight and manufacturing costs but also for development of novel designs. Even though many papers have addressed the superplastic deformation characteristics of these alloys it is essential for their exploitation to determine and to understand the effect of the forming process on their mechanical pro...
Indian Academy of Sciences (India)
R Sahu; V K B Kota
2014-04-01
The spectroscopic properties of 64Zn and 64Ni are calculated within the framework of the deformed shell model (DSM) based on Hartree–Fock states. GXPF1A interaction in 1 $f_{7/2}$, 2$p_{3/2}$, 1$f_{5/2}$ and 2$p_{1/2}$ space with 40Ca as the core is employed. After ensuring that DSM gives good description of the spectroscopic properties of low-lying levels in these two nuclei considered, nuclear transition matrix elements (NTME) for the neutrinoless positron double beta decay (0$\
Directory of Open Access Journals (Sweden)
Myszka D.
2014-10-01
Full Text Available In this article, an attempt was made to determine the effect of dynamic load on the austempered ductile iron resistance obtained under different conditions of heat treatment. Tests were carried out on six types of cylindrical ductile iron samples austempered at 320, 370 and 400oC for 30 and 180 minutes. For each type of material, two samples were collected. As a next step in the investigations, the samples were subjected to a Taylor impact test. The samples after striking a non-deformable, rigid target were deformed on their front face. After Taylor test, a series of material tests was performed on these samples, noting a significant increase of hardness in the deformed part. This was particularly well visible in the ductile iron isothermally quenched at higher temperatures of 370 and 400oC. Inthezone of sample deformation, an increase in the content of ferromagnetic phase was also reported, thus indicating the occurrence of martensitic transformation in the microstructure containing mechanically unstable austenite. A significant amount of deformed graphite was also observed, which was a symptom of the deformation process taking place in samples. The ductile iron was characterized by high toughness and high resistance to the effect of dynamic loads, especially as regards the grade treated at a temperature of 370oC.
Liu, Keming; Jiang, Zhengyi; Zhou, Haitao; Lu, Deping; Atrens, Andrej; Yang, Yanling
2015-11-01
The effect of heat treatment on the microstructure, electrical conductivity, and tensile strength of deformation-processed Cu-7Cr in situ composites produced by thermo-mechanical processing was investigated. The Cr fibers in the Cu-7Cr in situ composite underwent coarsening, break-up, and spheroidization after exposure to elevated temperatures. The conductivity and tensile strength of the in situ composite first increased with increasing isochronal heat treatment temperature, reached a peak value, and decreased at higher temperatures. The isothermal heat treatment temperature was determined to be 625 °C. The Z ( Z is an optimization parameter to evaluate the service performance of deformation-processed Cu-based in situ composites) value of the deformation-processed Cu-7Cr in situ composite, at ? = 7 ( ? is a cumulative cold deformation strain) after the heat treatment at 625 °C for 1 h, reached the peak value of 3.46 × 107 MPa2 % International Annealed Copper Standard (IACS). The isochronal heat treatment time was determined to be 1 h. The following combination of conductivity and tensile strength of the deformation-processed Cu-7Cr in situ composite with a cumulative cold deformation strain of eight after isochronal aging treatments for 1 h could be attained respectively as (i) 76.0% IACS and 889 MPa; (ii) 76.8% IACS and 876 MPa; or (iii) 77.5% IACS and 779 MPa.
Persistence of octupole correlations in sup 2 sup 3 sup 1 Ra
Fraile-Prieto, L M; Mach, H; Boutami, R; Aas, A J; Fogelberg, B; García-Raffi, L M; Grant, I S; Gulda, K; Hageboe, E; Kurcewicz, W; Kvasil, J; López, M J; Løvhøiden, G; Martínez, T; Rubio, B; Taín, J L; Tengblad, O
2001-01-01
The structure of sup 2 sup 3 sup 1 Ra, the heaviest odd Ra nucleus currently accessible for detailed spectroscopic investigation, has been studied in the beta sup - decay of sup 2 sup 3 sup 1 Fr. The main purpose has been to verify whether fast B(E1) rates and significant octupole correlations recently established in sup 2 sup 2 sup 9 Ra persist in sup 2 sup 3 sup 1 Ra. The excited states in sup 2 sup 3 sup 1 Ra have been determined for the first time. Spins and parities have been deduced from conversion electron measurements, while level half-lives in the ps and ns ranges have been measured with the Advanced Time Delayed beta gamma gamma(t) method. The moderately fast B(E1) rates found for transitions connecting the lowest-lying K suppi=5/2 sup+- and K suppi=1/2 sup+- bands, reveal the persistence of octupole collective effects in sup 2 sup 3 sup 1 Ra, although the B(E1) rates are lower than in sup 2 sup 2 sup 9 Ra. These findings reinforce the differences in the B(E1) systematics between isotonic Ra and Th ...
Effect of hot deformation on texture and magnetic properties of Sm-Co and Pr-Co alloys
Gabay, A. M.; Li, W. F.; Hadjipanayis, G. C.
2011-10-01
Nanocrystalline PrCo 5, SmCo 5 and Sm 2(Co,Fe,Mn) 17 alloys were subjected to a high-degree plastic deformation at 950 °C with the height reduction ranging from 70% to 95%. With increasing degree of deformation, the PrCo 5 and SmCo 5 magnets showed improvement of the deformation-induced [0 0 1] texture. The PrCo 5 alloys, known to develop a superior texture at the lower degrees of deformation, showed only modest improvement and their magnetic performance was undermined by a low coercivity. The SmCo 5 alloys had their texture markedly enhanced and, after height reduction by 94.5%, they exhibited a remanence of 8.6 kG, maximum energy product of 18 MGOe and an intrinsic coercivity of 22.8 kOe. No induced texture was found in the alloys based on the Sm 2Co 17 structure. The microstructures of the hot-deformed alloys were studied with a transmission electron microscopy, and possible mechanisms of the texture development in the RCo 5 alloys (R=Pr, Sm) are briefly discussed.
Oni, O O; Keswani, H; Aganga, M O
1983-01-01
We describe 8 children with 'windswept deformity'--a valgus deformity of 1 knee in association with a varus deformity of the other. The disease is a physeal osteochondrosis and conservative treatment with serial corrective plaster casts is as effective as corrective osteotomies.
Kozin, Scott H; Zlotolow, Dan A
2015-10-01
Madelung deformity of the wrist is more common in females and is often associated with Leri Weill dyschondrosteosis, a mesomelic form of dwarfism. Patients with Madelung deformity often report wrist deformity resulting from the prominence of the relatively long ulna. The typical Madelung deformity is associated with a Vickers ligament that creates a tether across the volar-ulnar radial physis that restricts growth across this segment. The distal radius deforms in the coronal (increasing radial inclination) and the sagittal (increasing volar tilt) planes. There is lunate subsidence and the proximal carpal row adapts to the deformity by forming an upside-down pyramid shape or triangle. Treatment depends on the age at presentation, degree of deformity, and magnitude of symptoms. Mild asymptomatic deformity warrants a period of nonsurgical management with serial x-ray examinations because the natural history is unpredictable. Many patients never require surgical intervention. Progressive deformity in the young child with considerable growth potential remaining requires release of Vickers ligament and radial physiolysis to prevent ongoing deterioration Concomitant ulnar epiphysiodesis may be necessary. Advanced asymptomatic deformity in older children with an unacceptable-appearing wrist or symptomatic deformity are indications for surgery. A dome osteotomy of the radius allows 3-dimensional correction of the deformity. Positive radiographic and clinical results after dome osteotomy have been reported. PMID:26341718
Robledo, A.; Moyano, L. G.
2008-03-01
We demonstrate that the dynamics toward and within the Feigenbaum attractor combine to form a q -deformed statistical-mechanical construction. The rate at which ensemble trajectories converge to the attractor (and to the repellor) is described by a q entropy obtained from a partition function generated by summing distances between neighboring positions of the attractor. The values of the q indices involved are given by the unimodal map universal constants, while the thermodynamic structure is closely related to that formerly developed for multifractals. As an essential component in our demonstration we expose, in great detail, the features of the dynamics of trajectories that either evolve toward the Feigenbaum attractor or are captured by its matching repellor. The dynamical properties of the family of periodic superstable cycles in unimodal maps are seen to be key ingredients for the comprehension of the discrete scale invariance features present at the period-doubling transition to chaos. Elements in our analysis are the following. (i) The preimages of the attractor and repellor of each of the supercycles appear entrenched into a fractal hierarchical structure of increasing complexity as period doubling develops. (ii) The limiting form of this rank structure results in an infinite number of families of well-defined phase-space gaps in the positions of the Feigenbaum attractor or of its repellor. (iii) The gaps in each of these families can be ordered with decreasing width in accordance with power laws and are seen to appear sequentially in the dynamics generated by uniform distributions of initial conditions. (iv) The power law with log-periodic modulation associated with the rate of approach of trajectories toward the attractor (and to the repellor) is explained in terms of the progression of gap formation. (v) The relationship between the law of rate of convergence to the attractor and the inexhaustible hierarchy feature of the preimage structure is elucidated. (vi) A "mean field" evaluation of the atypical partition function, a thermodynamic interpretation of the time evolution process, and a crossover to ordinary exponential statistics are given. We make clear the dynamical origin of the anomalous thermodynamic framework existing at the Feigenbaum attractor.
International Nuclear Information System (INIS)
We investigate the effect of disorder and mechanical deformation on a two-dimensional photonic crystal waveguide. The dispersion characteristics and transmittance of the waveguide are studied using the finite element method. Results show that the geometric change of the dielectric material perpendicular to the light propagation direction has a larger influence on the waveguide characteristics than that parallel to the light propagation direction. Mechanical deformation has an obvious influence on the performance of the waveguide. In particular, longitudinal deformed structure exhibits distinct optical characteristics from the ideal one. Studies on this work will provide useful guideline to the fabrication and practical applications based on photonic crystal waveguides. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
International Nuclear Information System (INIS)
Pure Cu of 99.98 wt.% purity has been processed at room temperature by diverse techniques of severe plastic deformation, namely equal-channel angular pressing (ECAP), high pressure torsion (HPT) and a combination of both in order to find out the evolution on the microstructural homogeneity for each of the processes and their combination. Starting with a grain size of ?60 ?m, severe plastic deformation has been introduced to the material while maintaining the sample dimensions unchanged through the processes of ECAP and HPT. A significant decrease in grain size was observed by transmission electronic microscopy (TEM). Microtensile and microhardness tests were carried out on the deformed material in the three processing conditions. A significant improvement of the tensile strength was promoted with admissible penalization on ductility
Directory of Open Access Journals (Sweden)
S. Choudhary
2011-01-01
Full Text Available We study the bias voltage dependent current characteristic in a deformed (8, 0 silicon carbide nanotube by applying self consistent non-equilibrium Green’s function formalism in combination with the density-functional theory to a two probe molecular junction constructed from deformed nanotube. The transmission spectra and electron density of states at zero bias shows a significant reduction in threshold in the case of both radially compressed and axially elongated nanotube. However, semiconductor to metal transition was not observed, though the results show large differences in current characteristic compared to a perfect nanotube.
Zakharova, G. G.; Astafurova, E. G.
2010-07-01
Hadfield steel single crystals have been deformed by high pressure torsion at room temperature (P=5GPa) for 1, 2, 3 revolutions. The resulting microstructure has been studied by means of transmission electron microscopy (TEM) and X-ray analysis. The size of fragments decreases with increasing number of revolutions due to interaction of slip dislocations, microbands and thin twins. As a result of severe plastic deformation, the microhardness of the Hadfield steel has been increased, and a portion of epsilon, ?' martensite has been found.
International Nuclear Information System (INIS)
Hadfield steel single crystals have been deformed by high pressure torsion at room temperature (P=5GPa) for 1, 2, 3 revolutions. The resulting microstructure has been studied by means of transmission electron microscopy (TEM) and X-ray analysis. The size of fragments decreases with increasing number of revolutions due to interaction of slip dislocations, microbands and thin twins. As a result of severe plastic deformation, the microhardness of the Hadfield steel has been increased, and a portion of ?, ?' martensite has been found.
Energy Technology Data Exchange (ETDEWEB)
Zakharova, G G; Astafurova, E G, E-mail: galinazg@yandex.r [Institute of Strength Physics and Materials Science, Siberian Branch of Russian Academy of Sciences, Akademichesky prospect 2/4, 634021, Tomsk (Russian Federation)
2010-07-01
Hadfield steel single crystals have been deformed by high pressure torsion at room temperature (P=5GPa) for 1, 2, 3 revolutions. The resulting microstructure has been studied by means of transmission electron microscopy (TEM) and X-ray analysis. The size of fragments decreases with increasing number of revolutions due to interaction of slip dislocations, microbands and thin twins. As a result of severe plastic deformation, the microhardness of the Hadfield steel has been increased, and a portion of {epsilon}, {alpha}' martensite has been found.
International Nuclear Information System (INIS)
The interplay between quadrupole and octupole distortions is analysed within a self-consistent description of many interacting boson systems. The coupling between these degrees of freedom is studied through the relative positions of the positive- and negative-parity rotational bands. Excited bandheads, moments of inertia and multipole moments are also analysed. (orig.)
Adebiyi, Babatunde Mattew
Material properties and performance are governed by material molecular chemistry structures and molecular level interactions. Methods to understand relationships between the material properties and performance and their correlation to the molecular level chemistry and morphology, and thus find ways of manipulating and adjusting matters at the atomistic level in order to improve material performance, are required. A computational material modeling methodology is investigated and demonstrated for a key cement hydrated component material chemistry structure of Calcium-Silicate-Hydrate (C-S-H) Jennite in this work. The effect of material ion exchanges on the mechanical stiffness properties and shear deformation behavior of hydrated cement material chemistry structure of Calcium Silicate Hydrate (C-S-H) Jennite was studied. Calcium ions were replaced with Magnesium ions in Jennite structure of the C-S-H gel. Different level of substitution of the ions was used. The traditional Jennite structure was obtained from the American Mineralogist Crystal Structure Database and super cells of the structures were created using a Molecular Dynamics Analyzer and Visualizer Material Studio. Molecular dynamics parameters used in the modeling analysis were determined by carrying out initial dynamic studies. 64 unit cell of C-S-H Jennite was used in material modeling analysis studies based on convergence results obtained from the elastic modulus and total energies. NVT forcite dynamics using COMPASS force field based on 200 ps dynamics time was used to determine mechanical modulus of the traditional C-S-H gel and the Magnesium ion modified structures. NVT Discover dynamics using COMPASS forcefield was used in the material modeling studies to investigate the influence of ionic exchange on the shear deformation of the associated material chemistry structures. A prior established quasi-static deformation method to emulate shear deformation of C-S-H material chemistry structure that is based on a triclinic crystal structure was used, by deforming the triclinic crystal structure at 0.2 degree per time step for 75 steps of deformation. It was observed that there is a decrease in the total energies of the systems as the percentage of magnesium ion increases in the C-S-H Jennite molecular structure systems. Investigation of effect of ion exchange on the elastic modulus shows that the elastic stiffness modulus tends to decrease as the amount of Mg in the systems increases, using either COMPASS or universal force field. On the other hand, shear moduli obtained after deforming the structures computed from the stress-strain curve obtained from material modeling increases as the amount of Mg increases in the system. The present investigations also showed that ultimate shear stress obtained from predicted shear stress---strain also increases with amount of Mg in the chemistry structure. Present study clearly demonstrates that computational material modeling following molecular dynamics analysis methodology is an effective way to predict and understand the effective material chemistry and additive changes on the stiffness and deformation characteristics in cementitious materials, and the results suggest that this method can be extended to other materials.
Kuranova, N. N.; Gunderov, D. V.; Uksusnikov, A. N.; Luk'yanov, A. V.; Yurchenko, L. I.; Prokof'ev, E. A.; Pushin, V. G.; Valiev, R. Z.
2009-12-01
Effect of annealing on the structural and phase transformations and mechanical properties of large-size samples of the Ti49.4Ni50.6 alloy preliminary subjected to severe plastic deformation by torsion under a high pressure (HPT) is studied. The study was performed by transmission and scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, and measurements of mechanical properties. The annealing was found to result in the nanocrystallization of initial samples amorphized by HPT. In this alloy, the high-strength uniform nanostructured state is formed the size of nanocrystalline grains of which and the mechanical properties depend on the temperature and time of annealing.
Energy Technology Data Exchange (ETDEWEB)
Singh, Ranjana; Lal, Shree P. [Birla Institute of Technology, Patna (India); Misra, Ashok [RTC Institute of Technology, Ranchi (India)
2015-02-15
This paper presents experimental results on intermittent electromagnetic radiation during plastic deformation of Cu-Ni alloys under tension and compression modes of deformation. On the basis of the nature of electromagnetic radiation signals, oscillatory or exponential, results show that the compression increases the viscous coefficient of Cu-Ni alloys during plastic deformation. Increasing the percentage of solute atoms in Cu-Ni alloys makes electromagnetic radiation strength higher under tension. The electromagnetic radiation emission occurs at smaller strains under compression showing early onset of plastic deformation. This is attributed to the role of high core region tensile residual stresses in the rolled Cu-Ni alloy specimens in accordance with the Bauschinger effect. The distance between the apexes of the dead metal cones during compression plays a significant role in electromagnetic radiation parameters. The dissociation of edge dislocations into partials and increase in internal stresses with increase in solute percentage in Cu-Ni alloys under compression considerably influences the electromagnetic radiation frequency.
DEFF Research Database (Denmark)
?epkowski, S. P.; Gorczyca, I.
2013-01-01
The deformation potentials acz?D1, act?D2, D3, D4, and D5 are determined for random AlGaN and InGaN alloys using electronic band structure calculations based on the density functional theory. A sublinear composition dependence is obtained for acz?D1 and D3 in AlGaN, and D3 in InGaN, whereas superlinear behavior on composition is found foract?D2, D4, and D5 in AlGaN, and act?D2and D5 in InGaN. The optical polarization properties of nitride quantum wells are very well described by the k·p method when the obtained deformation potentials are included. In m-plane AlGaN/AlN and InGaN/GaN quantum wells, the difference between the interband transition energies for light polarized parallel and orthogonal to the crystalline c axis compares more favorably to experimental data, than when deformation potentials previously reported in literature are used.
Kruckenberg, S. C.; Tikoff, B.
2012-12-01
The segregation, migration, and extraction of melt - and the emplacement and assembly of the melts as plutonic systems - are major controls on mass and heat transfer in the lithosphere. The distribution of partial melts at the grain scale, and partially molten rocks at larger spatial scales, exerts a profound influence on rock rheology, and is of significance for melt segregation, dynamic weakening, and strain localization at a variety of lithospheric levels. Evaluating the rheological effects of melt in the lithosphere requires insight into the relative effects of stress-driven segregation, strain and reaction history, and intrinsic rock properties of naturally deformed lithospheric sections. Melt segregation and distribution are dynamically linked at a variety of spatial scales to relative motion between the melt and solid phase in deforming partially molten rocks, which gives rise to an evolving melt topology and porosity-permeability structure. The extraction of melt from grain boundaries requires connectivity into a channelized migration network or through structural fabrics that allow for the horizontal and vertical transfer of melt in the crust, compelling examples of which have been demonstrated in migmatite-granite complexes in the crust, dike and vein networks in the crust and mantle, and for reactive melt migration pathways in the upper mantle. Numerical models and experimental rock deformation studies have provided important insights into the mechanisms of melt segregation, geometric characteristics of channelized melt migration networks, and the rheological consequences of melt mobilization. However, field-based and microstructural investigations of exhumed lithospheric sections remain critical for evaluating relationships between deformation and melt flow processes at geologically relevant scales, and under natural deformation conditions. For example, field-based studies in the Twin Sisters ultramafic complex (Washington State) document melt migration geometries that differ from patterns predicted by numerical and experimental studies of stress-driven melt segregation. Dunite melt bands in low strain regions of the Twin Sisters complex typically form high angle conjugate geometries, but in highly deformed portions of the host peridotites their geometries systematically become more subparallel. Structural and textural observations suggest that melt flow was contemporaneous with deformation and therefore the organization of the reactive melt flow network was dynamically linked to the magnitude of viscous strain and localization phenomena in the host peridotites. These observations underscore the importance of field, microstructural, and textural studies in tectonic systems that experienced the sequential or coeval effects of melt extraction, migration or accumulation (e.g., migmatite-granite complexes). The permeability of melt flow networks, the distribution of melt and melt connectivity in the orogenic crust, and the timing of partial melting relative to deformation, all affect the efficiency of melt transfer in the lithosphere. The rheological evolution of partially molten rocks further significantly affects the ability of the melt-rich crust to mobilize into zones of active deformation, such as during the formation of migmatite domes (e.g., the Naxos dome, Greece).
q-Deformed Dynamics and Virial Theorem
Zhang, Jian-zu
2002-01-01
In the framework of the q-deformed Heisenberg algebra the investigation of $q$-deformation of Virial theorem explores that q-deformed quantum mechanics possesses better dynamical property. It is clarified that in the case of the zero potential the theoretical framework for the q-deformed Virial theorem is self-consistent. In the selfadjoint states the q-deformed uncertainty relation essentially deviates from the Heisenberg one.
Experiment and theory of a drift wave in the levitated octupole
International Nuclear Information System (INIS)
A very coherent 30 kHz drift wave is observed in the Levitated Toroidal Octupole at the University of Wisconsin - Madison. The density and floating potential fluctuations have a well-defined spatial structure in the poloidal magnetic field. Radially the wave has a standing wave structure with amplitude peaked in regions of locally bad magnetic curvature. Poloidally the wave has a standing wave structure with odd symmetry; nodes are located in the regions of locally good magnetic curvature. The wave propagates toroidally in the electron diamagnetic drift direction with a wavelength of 20 centimeters. No changes occur in the wave structure as the plasma is varied over three orders of magnitude in density and beta
Appraising nuclear octupole moment contributions to the hyperfine structures in $^{211}$Fr
Sahoo, B K
2015-01-01
Hyperfine structures of $^{211}$Fr due to the interactions of magnetic dipole ($\\mu$), electric quadrupole ($Q$) and magnetic octupole ($\\Omega$) moments with the electrons are investigated using the relativistic coupled-cluster (RCC) theory with an approximation of singles, doubles and important valence triples excitations in the perturbative approach. Validity of our calculations are substantiated by comparing the results with their available experimental values. Its $Q$ value has also been elevated by combining the measured hyperfine structure constant of the $7p \\ ^2P_{3/2}$ state with our improved calculation. Considering the preliminary value of $\\Omega$ from the nuclear shell-model, its contributions to the hyperfine structures up to the $7d \\ ^2D_{5/2}$ low-lying states in $^{211}$Fr are estimated. Energy splittings of the hyperfine transitions in many states have been assessed to find out suitability to carry out their precise measurements so that $\\Omega$ of $^{211}$Fr can be inferred from them unam...
Gyromagnetic ratios and octupole collectivity in the structure of the 90-96Zr isotopes
International Nuclear Information System (INIS)
Shell model calculations have been performed for low-excitation states in the Zr isotopes between 90Zr and 96Zr with an emphasis on the g factors and electromagnetic decay rates for the lowest 2+ and 3- states. Overall the 2+ states are reasonably well described. In contrast, the 3- states present a puzzle because the measured g factors imply a single-particle configuration whereas the experimental E3 transition rates imply collective structures that cannot be explained by shell model calculations. A consistent description of the 3- states in 90Zr and 96Zr is sought in terms of coupling between the single-particle structure and a collective octupole vibration
Deformation and properties of ribbons of amorphous FeCo80-xSi15Bx alloys
International Nuclear Information System (INIS)
Change in morphology of shear bands, propagation of micro- and macrocracks, structure as well as coercive force Hc of rolled strips of Fe5Co80-xSi15Bx amorphous alloys, is studied, where x has the following values: 8.2; 10; 11.8 at.%. The found essential (more than 200 times) increase of Hc after deformation is explained by appearance of internal stresses, microcracks and nuclei of crystal phase
International Nuclear Information System (INIS)
The surprising answer to this question Is nucleon deformed? is : Yes. The evidence comes from a study of the quark model of the single nucleon and when it is found in a nucleus. It turns out that many of the long standing problems of the Naive Quark Model are taken care of if the nucleon is assumed to be deformed. Only one value of the parameter PD ?1/4 (which specifies deformation) fits gA (the axial vector coupling constant) for all the semileptonic decay of baryons, the F/D ratio, the pion-nucleon-delta coupling constant fsub(?N?), the double delta coupling constant1 fsub(???), the Ml transition moment ??N and g1p the spin structure function of proton2. All this gives strong hint that both neutron and proton are deformed. It is important to look for further signatures of this deformation. When this deformed nucleon finds itself in a nuclear medium its deformation decreases. So much that in a heavy nucleus the nucleons are actually spherical. We look into the Gamow-Teller strengths, magnetic moments and magnetic transition strengths in nuclei to study this property. (author). 15 refs
International Nuclear Information System (INIS)
Results of proton and electron inelastic scattering suggest that the interpretation of the 51--71--91- sequence in 144Nd as simple quadrupole-octupole-coupled states neglects large ?(f7/2i13/2)5,7,9 components and, therefore, that the interpretation of the 12+ state at 4354 keV as a double-octupole-phonon state (61+circle-times octupole circle-times octupole) given by Bargioni et al. [Phys. Rev. C 51, R1057 (1995)] may be too simple. It is suggested that measurements of the 91- state via single-neutron-stripping reactions and intermediate energy proton scattering can help determine the underlying structure of the 4354 keV state. copyright 1996 The American Physical Society
Confinement properties of high energy density plasmas in the Wisconsin levitated octupole
International Nuclear Information System (INIS)
The confinement of particles and energy is critically dependent on the plasma-wall interaction. Results of a study detailing this interaction are presented. High power ICRF heated and gun afterglow plasmas were studied to detail the mechanisms determining particle and energy confinement. An extensive zero-D simulation code is used to assist in interpreting the experimental data. Physically reasonable models for plasma surface interactions, time dependent coronal treatment of impurities and multiple region treatment of neutrals are used in modeling the plasma. Extensive diagnostic data are used to verify the model. Non-heated plasmas decay from 28 to 3 eV allowing clear identification of wall impact energy thresholds for desorption and particle reflection. The charge state distribution of impurities verifies the reflux to plasma diffusion rate ratio. Close agreement between the simulation and experimental data is found
Directory of Open Access Journals (Sweden)
Jan Valí?ek
2015-11-01
Full Text Available The paper solves the problem of the nonexistence of a new method for calculation of dynamics of stress-deformation states of deformation tool-material systems including the construction of stress-strain diagrams. The presented solution focuses on explaining the mechanical behavior of materials after cutting by abrasive waterjet technology (AWJ, especially from the point of view of generated surface topography. AWJ is a flexible tool accurately responding to the mechanical resistance of the material according to the accurately determined shape and roughness of machined surfaces. From the surface topography, it is possible to resolve the transition from ideally elastic to quasi-elastic and plastic stress-strain states. For detecting the surface structure, an optical profilometer was used. Based on the analysis of experimental measurements and the results of analytical studies, a mathematical-physical model was created and an exact method of acquiring the equivalents of mechanical parameters from the topography of surfaces generated by abrasive waterjet cutting and external stress in general was determined. The results of the new approach to the construction of stress-strain diagrams are presented. The calculated values agreed very well with those obtained by a certified laboratory VÚHŽ.
Di-neutron correlation in soft octupole excitations of neutron-rich Ni isotopes beyond N=50
Serizawa, Yasuyoshi; Matsuo, Masayuki
2008-01-01
We investigate low-lying octupole response of neutron-rich Ni isotopes beyond the N=50 shell closure using the Skyrme-Hartree-Fock-Bogoliubov mean-fields and the continuum quasi-particle random phase approximation. Performing detailed numerical analyses employing the Skyrme parameter set SLy4 and a density-dependent delta interaction of the mixed type, we show that a neutron mode emerges above the neutron separation energy as a consequence of the weak binding of neutrons and...
Backbending in deformed nuclei
International Nuclear Information System (INIS)
In the last few years, the deformed nuclei situated in the region of the rare earth elements have been investigated intensively. Thereby several new properties, for instance the backbending effect and the existence of decoupled bands, have been observed. These phenomena are described in this paper. (orig.)
High-temperature deformation behavior and thermal properties of an Ni30Co17Fe53 alloy
Energy Technology Data Exchange (ETDEWEB)
Lee, Kwang Seok; Yoon, Dong Hyun [Korea Institute of Materials Science, Changwon (Korea, Republic of). Materials Deformation Group; Jung, Joong Eun; Chang, Young Won [POSTECH, Pohang (Korea, Republic of). Dept. of Materials Science and Engineering; Lee, Jung Hwan [Korea Institute of Materials Science, Changwon (Korea, Republic of). Technical Support Div.
2012-07-15
High temperature deformation behavior of a Ni30Co17Fe53 alloy has been investigated by carrying out hot compression tests at temperatures ranging from 600 C to 1 150 C under strain rates between 10{sup -5} and 1 s{sup -1}. Both the temperature and strain-rate dependence of the flow stress were found to be described by a hyperbolic sine function. Hot formability of this alloy was also estimated by constructing an empirical processing map based on a dynamic materials model, from which the region with high power dissipation efficiency was exhibited as a feasible combination of processing condition at around 1 150 C and 10{sup -2}s{sup -1}. Three different thermo-mechanical treatment processes were adopted for hot-forging to investigate its influence on microstructure and subsequent thermal expansion and thermal conductivity. (orig.)
Kim, Eunjung; Guilak, Farshid; Haider, Mansoor A
2010-03-01
The pericellular matrix (PCM) is the narrow tissue region surrounding all chondrocytes in articular cartilage and, together, the chondrocyte(s) and surrounding PCM have been termed the chondron. Previous theoretical and experimental studies suggest that the structure and properties of the PCM significantly influence the biomechanical environment at the microscopic scale of the chondrocytes within cartilage. In the present study, an axisymmetric boundary element method (BEM) was developed for linear elastic domains with internal interfaces. The new BEM was employed in a multiscale continuum model to determine linear elastic properties of the PCM in situ, via inverse analysis of previously reported experimental data for the three-dimensional morphological changes of chondrons within a cartilage explant in equilibrium unconfined compression (Choi, et al., 2007, "Zonal Changes in the Three-Dimensional Morphology of the Chondron Under Compression: The Relationship Among Cellular, Pericellular, and Extracellular Deformation in Articular Cartilage," J. Biomech., 40, pp. 2596-2603). The microscale geometry of the chondron (cell and PCM) within the cartilage extracellular matrix (ECM) was represented as a three-zone equilibrated biphasic region comprised of an ellipsoidal chondrocyte with encapsulating PCM that was embedded within a spherical ECM subjected to boundary conditions for unconfined compression at its outer boundary. Accuracy of the three-zone BEM model was evaluated and compared with analytical finite element solutions. The model was then integrated with a nonlinear optimization technique (Nelder-Mead) to determine PCM elastic properties within the cartilage explant by solving an inverse problem associated with the in situ experimental data for chondron deformation. Depending on the assumed material properties of the ECM and the choice of cost function in the optimization, estimates of the PCM Young's modulus ranged from approximately 24 kPa to 59 kPa, consistent with previous measurements of PCM properties on extracted chondrons using micropipette aspiration. Taken together with previous experimental and theoretical studies of cell-matrix interactions in cartilage, these findings suggest an important role for the PCM in modulating the mechanical environment of the chondrocyte. PMID:20459199
Search for the two-phonon octupole vibrational state in {sup 208}Pb
Energy Technology Data Exchange (ETDEWEB)
Blumenthal, D.J.; Henning, W.; Janssens, R.V.F. [and others
1995-08-01
We performed an experiment to search for the two-phonon octupole vibrational state in {sup 208}Pb. Thick targets of {sup 208}Pb, {sup 209}Bi, {sup 58,64}Ni, and {sup 160}Gd were bombarded with 1305 MeV beams of were bombard {sup 208}Pb supplied by ATLAS. Gamma rays were detected using the Argonne-Notre Dame BGO gamma-ray facility, consisting of 12 Compton-suppressed germanium detectors surrounding an array of 50 BGO scintillators. We identified some 30 known gamma rays from {sup 208}Pb in the spectra gated by the 5{sup -} {yields} 3{sup -} and 3{sup -} {yields} 0{sup +} transitions in {sup 208}Pb. In addition, after unfolding these spectra for Compton response, we observed broad coincident structures in the energy region expected for the 2-phonon states. Furthermore, we confirmed the placement of a 2485 keV line observed previously in {sup 207}Pb and find no evidence consistent with the placement of this line in {sup 208}Pb. We are currently in the process of investigating the origin of the broadened lines observed in the spectra, extracting the excitation probability of states in {sup 208}Pb, and determining the relative probability of mutual excitation and neutron transfer in this reaction. An additional experiment is also being performed to collect much higher statistics germanium-germanium coincidence data for the thick {sup 208}Pb target.
New results for the missing quantum numbers labelling the quadrupole and octupole boson basis
International Nuclear Information System (INIS)
The many 2k-pole boson states, |Nkvk?kIkMk) with k = 2, 3, realize the irreducible representation (IR) for the group reduction chains SU(2k + 1) R2k+1 R3 R2. They have been analytically studied and widely used for the description of nuclear systems. However, no analytical expression for the degeneracy d(k)v(I) of the R2k+1 IR, determined by the reduction R2k+1 R3, with k = 2, 3 is available. Thus, the number of distinct values taken by ?k has been so far obtained by solving some complex equations. Here we derive analytical expressions for the degeneracy d(k)v(I) (k = 2, 3), characterizing the octupole and quadrupole boson states, respectively. The merit of this work consists of the fact that it completes the analytical expressions for the 2k-pole boson basis for k = 2, 3. The general case of R2l+1 IR representation degeneracy is also presented and a compact analytical expression for d(l)v(I) is derived
Core breaking and octupole low-spin states in $^{207}$ Tl
We propose to study the low-spin level structure of the $^{207}$Tl nucleus populated by the $\\beta$- decay of $^{207}$Hg. While $^{207}$Tl is a single-proton hole nucleus, the majority of the observed states will have threeparticle structure thus requiring the breaking of the neutron or proton core, or a collective octupole phonon coupled to the single proton hole. Thus information will be obtained on the single particle orbitals in the vicinity of the N=126 and Z=82 magic numbers, and on the size of the shell gap. The results will be used to improve the predictive power of the shell model for more exotic nuclei as we move to lighter N=126 nuclei.The experiment will use the ISOLDE Decay station, and will take advantage of the $^{207}$Hg beam from the molten lead target. A test on the feasibility to produce $^{208}$Hg beam from the same target, with the aim to study the $\\beta$-decay into $^{208}$Tl, could be performed at the same time.
Low frequency turbulence, particle and heat transport in the Wisconsin levitated octupole
International Nuclear Information System (INIS)
Low frequency turbulence in the drift frequency range and its relation to the observed particle transport in the Wisconsin Levitated Octupole has been studied with a microwave scattering apparatus. The experimental parameters were T/sub e/ approx. T/sub i/ 13 cm-3, 200 G < B/sub p-average/ < 1.25 kG. The effect of shear on the transport was studied by the addition of a small toroidal field. By matching experimentally measured density profiles to those given by numerical solutions of the transport equations, diffusion coefficients were obtained. Time dependent density fluctuation spectra were measured with an 8 mm microwave scattering diagnostic to correlate the drift wave portion of the spectrum with the observed diffusion. The density fluctuation spectrum of low frequency (1 kHz < ? < 6 MHz) turbulence was measured for several values of perpendicular wavenumber, k/sub perpendicular to/. Electron heat transport was studied by fitting experimentally measured electron temperature profiles to those predicted by numerical solutions of electron energy transport equation
International Nuclear Information System (INIS)
A combination of molecular dynamics (MD), continuum elasticity and FEM is used to predict the effect of CNT orientation on the shear modulus of SWCNT-polymer nanocomposites. We first develop a transverse-isotropic elastic model of SWCNTs based on the continuum elasticity and MD to compute the transverse-isotropic elastic constants of SWCNTs. These constants are then used in an FEM-based simulation to investigate the effect of SWCNT alignment on the shear modulus of nanocomposites. Furthermore, shear stress distributions along the nanotube axis and over its cross-sectional area are investigated to study the effect of CNT orientation on the shear load transfer. - Highlights: ? A transverse-isotropic elastic model of SWCNTs is presented. ? A hierarchical MD/FEM multiscale model of SWCNT-polymer composites is developed. ? Behavior of these nanocomposites under shear deformation is studied. ? A symmetric shear stress distribution occurs only in SWCNTs with 45o orientation. ? The total shear load sustained is greatest in the case of 45o orientation.
International Nuclear Information System (INIS)
Transmission electron microscopy used to evaluate the deformation (creep, fatigue and tensile) induced microstructure of 304 SS, Incoloy 800, 330 SS and three of the experimental alloys (E19, E23 and E36) obtained from the National Alloy Program clearly shows that the relationship between the subgrain size (lambda) and the applied stress (sigma) obeys the equation lambda = Ab (sigma/E)-1 where A is a constant of the order of 4, b the Burgers rector and E is Young's modulus. Hot-hardness studies on 304 SS, 316 SS, Incoloy 800, 2 1/4 Cr-1 Mo steels, 330 SS, Inconel 718, PE-16, Inconel 706, M-813 and the above three experimental alloys suggests that reasonable effective activation energies for creep may be obtained through the use of the hardness test as a strength microprobe tool. The ordering of the strength levels obtained through hot-hardness follows quite closely that obtained in tensile tests when those data are available
Thermodynamic Geometry of Deformed Bosons and Fermions
Mirza, Behrouz; Mohammadzadeh, Hosein
2012-01-01
We construct the thermodynamic geometry of an ideal q-deformed boson and fermion gas. We investigate some thermodynamic properties such as the stability and statistical interaction. It will be shown that the statistical interaction of q-deformed boson gas is attractive, while it is repulsive for the q-deformed fermion one. Also, we will consider the singular point of the thermodynamic curvature to obtain some new results about the condensation of q-deformed bosons and show t...
Directory of Open Access Journals (Sweden)
Ju Shin-Pon
2011-01-01
Full Text Available Abstract The effect of uni-axial strain on the electronic properties of (8,0 zigzag and (5,5 armchair boron nitride nanotubes (BNNT is addressed by density functional theory calculation. The stress-strain profiles indicate that these two BNNTS of differing types display very similar mechanical properties, but there are variations in HOMO-LUMO gaps at different strains, indicating that the electronic properties of BNNTs not only depend on uni-axial strain, but on BNNT type. The variations in nanotube geometries, partial density of states of B and N atoms, B and N charges are also discussed for (8,0 and (5,5 BNNTs at different strains.
Czech Academy of Sciences Publication Activity Database
Günther, A.; Brokmeier, H. G.; Petrovský, Eduard; Siemes, H.; Helming, K.; Quade, H.
A74, Suppl. (2002), s. S1080-S1082. ISSN 0947-8396 Institutional research plan: CEZ:AV0Z3012916 Keywords : magnetic properties * iron ore * Brazil * magnetic susceptibility Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 2.231, year: 2002
Mebs, R W; Mcadam, D J
1947-01-01
A resume is given of an investigation of the influence of plastic deformation and of annealing temperature on the tensile and shear elastic properties of high strength nonferrous metals and stainless steels in the form of rods and tubes. The data were obtained from earlier technical reports and notes, and from unpublished work in this investigation. There are also included data obtained from published and unpublished work performed on an independent investigation. The rod materials, namely, nickel, monel, inconel, copper, 13:2 Cr-Ni steel, and 18:8 Cr-Ni steel, were tested in tension; 18:8 Cr-Ni steel tubes were tested in shear, and nickel, monel, aluminum-monel, and Inconel tubes were tested in both tension and shear. There are first described experiments on the relationship between hysteresis and creep, as obtained with repeated cyclic stressing of annealed stainless steel specimens over a constant load range. These tests, which preceded the measurements of elastic properties, assisted in devising the loading time schedule used in such measurements. From corrected stress-set curves are derived the five proof stresses used as indices of elastic or yield strength. From corrected stress-strain curves are derived the secant modulus and its variation with stress. The relationship between the forms of the stress-set and stress-strain curves and the values of the properties derived is discussed. Curves of variation of proof stress and modulus with prior extension, as obtained with single rod specimens, consist in wavelike basic curves with superposed oscillations due to differences of rest interval and extension spacing; the effects of these differences are studied. Oscillations of proof stress and modulus are generally opposite in manner. The use of a series of tubular specimens corresponding to different amounts of prior extension of cold reduction gave curves almost devoid of oscillation since the effects of variation of rest interval and extension spacing were removed. Comparison is also obtained between the variation of the several properties, as measured in tension and in shear. The rise of proof stress with extension is studied, and the work-hardening rates of the various metals evaluated. The ratio between the tensile and shear proof stresses for the various annealed and cold-worked tubular metals is likewise calculated. The influence of annealing or tempering temperature on the proof stresses and moduli for the cold-worked metals and for air-hardened 13:2 Cr-Ni steel is investigated. An improvement of elastic strength generally is obtained, without important loss of yield strength, by annealing at suitable temperature. The variation of the proof stress and modulus of elasticity with plastic deformation or annealing temperature is explained in terms of the relative dominance of three important factors: namely, (a) internal stress, (b) lattice-expansion or work-hardening, and (c) crystal reorientation. Effective values of Poisson's ratio were computed from tensile and shear moduli obtained on tubular specimens. The variation of Poisson's ratio with plastic deformation and annealing temperature is explained in terms of the degree of anisotropy produced by changes of (a) internal stress and (b) crystal orientation.
Energy Technology Data Exchange (ETDEWEB)
Adachi, Nozomu; Todaka, Yoshikazu, E-mail: todaka@me.tut.ac.jp; Umemoto, Minoru [Department of Mechanical Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku, Toyohashi, Aichi 441-8580 (Japan); Yokoyama, Yoshihiko [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan)
2014-09-29
The mechanism of plastic deformation in bulk metallic glasses (BMGs) is widely believed to be based on a shear transformation zone (STZ). This model assumes that a shear-induced atomic rearrangement occurs at local clusters that are a few to hundreds of atoms in size. It was recently postulated that the potential energy barrier for STZ activation, W{sub STZ}, calculated using the cooperative shear model, is equivalent to the activation energy for ?-relaxation, E{sub ?}. This result suggested that the fundamental process for STZ activation is the mechanically activated ?-relaxation. Since the E{sub ?} value and the glass transition temperature T{sub g} of BMGs have a linear relation, that is, because E{sub ?}???26RT{sub g}, the composition of the BMG determines the ease with which the STZ can be activated. Enthalpy relaxation experiments revealed that the BMG Zr{sub 50}Cu{sub 40}Al{sub 10} when deformed by high-pressure torsion (HPT) has a lower E{sub ?} of 101?kJ/mol. The HPT-processed samples accordingly exhibited tensile plastic elongation (0.34%) and marked decreases in their yield strength (330?MPa). These results suggest that mechanically induced structural defects (i.e., the free volume and the anti-free volume) effectively act to reduce W{sub STZ} and increase the number of STZs activated during tensile testing to accommodate the plastic strain without requiring a change in the composition of the BMG. Thus, this study shows quantitatively that mechanically induced structural defects can overcome the compositional limitations of E{sub ?} (or W{sub STZ}) and result in improvements in the mechanical properties of the BMG.
International Nuclear Information System (INIS)
The mechanism of plastic deformation in bulk metallic glasses (BMGs) is widely believed to be based on a shear transformation zone (STZ). This model assumes that a shear-induced atomic rearrangement occurs at local clusters that are a few to hundreds of atoms in size. It was recently postulated that the potential energy barrier for STZ activation, WSTZ, calculated using the cooperative shear model, is equivalent to the activation energy for ?-relaxation, E?. This result suggested that the fundamental process for STZ activation is the mechanically activated ?-relaxation. Since the E? value and the glass transition temperature Tg of BMGs have a linear relation, that is, because E????26RTg, the composition of the BMG determines the ease with which the STZ can be activated. Enthalpy relaxation experiments revealed that the BMG Zr50Cu40Al10 when deformed by high-pressure torsion (HPT) has a lower E? of 101?kJ/mol. The HPT-processed samples accordingly exhibited tensile plastic elongation (0.34%) and marked decreases in their yield strength (330?MPa). These results suggest that mechanically induced structural defects (i.e., the free volume and the anti-free volume) effectively act to reduce WSTZ and increase the number of STZs activated during tensile testing to accommodate the plastic strain without requiring a change in the composition of the BMG. Thus, this study shows quantitatively that mechanically induced structural defects can overcome the compositional limitations of E? (or WSTZ) and result in improvements in the mechanical properties of the BMG.
Multipole modes in deformed nuclei within the finite amplitude method
Kortelainen, M.; Hinohara, N.; Nazarewicz, W.
2015-11-01
Background: To access selected excited states of nuclei, within the framework of nuclear density functional theory, the quasiparticle random phase approximation (QRPA) is commonly used. Purpose: We present a computationally efficient, fully self-consistent framework to compute the QRPA transition strength function of an arbitrary multipole operator in axially deformed superfluid nuclei. Methods: The method is based on the finite amplitude method (FAM) QRPA, allowing fast iterative solution of QRPA equations. A numerical implementation of the FAM-QRPA solver module has been carried out for deformed nuclei. Results: The practical feasibility of the deformed FAM module has been demonstrated. In particular, we calculate the quadrupole and octupole strengths in a heavy deformed nucleus 240Pu, without any truncations in the quasiparticle space. To demonstrate the capability to calculate individual QRPA modes, we also compute low-lying negative-parity collective states in 154Sm. Conclusions: The new FAM implementation enables calculations of the QRPA strength function throughout the nuclear landscape. This will facilitate global surveys of multipole modes and ? decays and will open new avenues for constraining the nuclear energy density functional.
Energy Technology Data Exchange (ETDEWEB)
Benay, O. (SNECMA, Dept. des Materiaux et Procedes, YKOM 4, 91 Evry (France)); Lucas, A.S. (SNECMA, Dept. des Materiaux et Procedes, YKOM 4, 91 Evry (France)); Obadia, S. (SNECMA, Dept. des Materiaux et Procedes, YKOM 4, 91 Evry (France)); Vadon, A. (ISGMP, Ile du Saulcy, 57 Metz (France))
1994-01-01
Superplastic tensile tests have been carried out up to elongations of 20 and 100 % at 925 C on a thin TA6V slab. To study the influence of texture, test pieces axes have been oriented with four angles from the rolling direction. No pronounced effect of texture on superplastic behaviour is clearly enhanced by the usual stress/strain rate law. The type of microstructural changes and the variations of the texture intensity may be correlated with the strain range. As for the starting material, tensile properties of the stretched material at room temperature are strongly dependent on texture. (orig.)
International Nuclear Information System (INIS)
Document available in extended abstract form only. In Switzerland, the international research project Mont Terri investigates the Opalinus Clay (Jurassic formation) in the underground rock laboratory (URL) Mont Terri. The Opalinus Clay is subdivided into different facies (sandy, shaly, and carbonate rich facies). In the Mont Terri URL the sandy facies is less abundant and only a relatively thin layer of the carbonate rich facies is present. The currently favored HLRW repository site in Switzerland, however, is supposed to be in the sandy facies of the Opalinus Clay. Yet, most of the investigations focused on the shaly facies. Generally the understanding of the relation of properties and performances of clays and clay-stones is poor which is relevant for mineralogical micro fabric but also mechanical processes. For the safety assessment of the repository models describing both chemical and mechanical processes are required. Such models have to be based on a solid understanding of the mechanisms behind the processes considered. With respect to the understanding of the deformation behavior of different Opalinus Clay samples, Klinkenberg et al. (2009) found the carbonates to play a major role. For different samples of the shaly facies they found carbonate to represent a kind of predetermined breaking planes. Therefore, carbonate rich materials showed lower mechanical strengths. Interestingly, they also observed the opposite when considering samples of the Callovo-Oxfordian clay, which is investigated in France. Considering the micro fabric of all samples suggests that the carbonate - mechanical strength relation depends on the type and amount of carbonates. Therefore, Kaufhold et al. investigated the micro fabric - mechanical strength relation of the sandy facies. They concluded that the sandy facies is comparable with the investigated samples of the Callovo-Oxfordian clay. The mechanical behavior of the shaly facies was already investigated. A detailed comparison of samples from both main facies of the Opalinus clay, however, is missing. In this study, therefore, the investigation of the sandy facies and shaly facies with focus on the relation between micro fabric, mineralogical composition, and mechanical deformation behavior is presented. The sandy and the shaly facies both show the same mineral inventory but different contents. The shaly facies has a clay mineral content between 60 to 70 wt% (within 10-15 wt% swellable phases), whereas the sandy facies only has a clay mineral content of 15-25% (within dev.peak approximately twice as high as it was found for the shaly facies. The results are supposed to improve the understanding of the mechanical properties of clays, particularly with respect to the variability of mineral composition, micro fabric, and mechanical behavior. (authors)
Butet, J; Bachelier, G; Russier-Antoine, I; Jonin, C; Benichou, E; Brevet, P-F
2010-08-13
Optical second-harmonic generation from gold nanoparticles is investigated both experimentally and theoretically. The contribution of octupoles is reported for the first time in the second-harmonic emission pattern, by using an harmonic polarization in the scattering plane. The experimental results presented here for particle sizes up to 100 nm are in excellent agreement with finite element method simulations involving the normal surface term only in the nonlinear polarization source. In addition, analytical calculations based on nonlinear Mie scattering theory clearly evidence the constructive and destructive interferences occurring between the dipolar and octupolar responses selected with this polarization configuration. PMID:20868074
Measurements of octupole collectivity in $^{220,222}$Rn and $^{222,224}$Ra using Coulomb excitation
Kruecken, R; Larsen, A; Hurst, A M; Voulot, D; Grahn, T; Clement, E; Wadsworth, R; Gernhaeuser, R A; Siem, S; Van duppen, P L E; Page, R; Barton, C J; Wenander, F J C; Huyse, M L; Iwanicki, J S; Warr, N V
2008-01-01
We propose to exploit the unique capability of ISOLDE to provide post-accelerated $^{220,222}$Rn and $^{222,224}$Ra ion beams from the REX facility to enable the Coulomb excitation of the first 3$^{-}$ states in these nuclei. By measuring the $\\gamma$-ray yields of the E1 decays from the 3$^{-}$ state using the MINIBALL array we can obtain the transition matrix elements. This will give quantitative information about octupole correlations in these nuclei. We require 22 shifts to fulfil the aims of the experiment.
Energy Technology Data Exchange (ETDEWEB)
Chen, A.Y.; Shi, S.S.; Tian, H.L. [School of Material Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China); Ruan, H.H. [Department of Mechanical Engineering, Hong Kong University of Science and Technology, Hong Kong (China); Li, X. [School of Material Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China); Pan, D., E-mail: feiyu.dpan@gmail.com [School of Material Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China); Lu, J. [College of Science and Engineering, City University of Hong Kong, Hong Kong (China)
2014-02-10
A layered and nanostructured (LN) stainless steel was fabricated by surface mechanical attrition treatment (SMAT) combined with warm co-rolling (WCR) in order to improve the low ductility of nanostructured metallic materials. The influences of rolling temperature and strain on the microstructure are investigated. The microstructure of LN steel is characterized by methods of transmission electron microscopy (TEM), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The experimental results reveal that the microstructure of LN steels presents a periodic distribution of nanocrystalline layer, ultra-fine grained layer and coarse grained layer with graded transition of grain size. The integrated effects of SMAT and WCR on the refinement of grain size, involving in dislocation subdivision, twinning and dynamic recrystallization, are discussed. The tensile properties of LN steels exhibit both high strength and good ductility resulting from good work hardening behavior. The strengthening mechanisms by grain size refinement, ??-martensite transformation and twinning are explored.
Deformed Mittag-Leffler Polynomials
Stankovic, Miomir S; Rajkovic, Predrag M
2010-01-01
The starting point of this paper are the Mittag-Leffler polynomials introduced by H. Bateman [1]. Based on generalized integer powers of real numbers and deformed exponential function, we introduce deformed Mittag-Leffler polynomials defined by appropriate generating function. We investigate their recurrence relations, differential properties and orthogonality. Since they have all zeros on imaginary axes, we also consider real polynomials with real zeros associated to them.
International Nuclear Information System (INIS)
Mechanical properties and TEM microstructure studies have been carried out of nanocrystalline titanium, Ti10Nb10Ta and Ti10Nb obtained by various technological routes, including: powder metallurgy (ball milling and hot pressing), Equal Channel Angular Pressing (ECAP), hydroextrusion (HE) and high pressure torsion (HPT). The HE processed material in the form of 20 mm rods was extruded at a strain rate of 2.5 x 102 s-1 to a diameter of 3 mm, which corresponds to the true strain of 3.8. Resulting Yield Strength (YS) at the crystal size below 80 nm exceeded 1000 MPa, i.e. attained a value of 3 times more than the initial material. Equal-Channel Angular Pressing (ECAP) at 723 K was applied to produce nanostructured titanium. Grain refinement was observed already after one pass (considerable number of grains with d 20=1000. The additions of Nb and Ta resulted in a similar grain refinement but lower hardness. Uniaxial hot pressing at 650 C, followed by vacuum annealing resulted in similar microhardness as for powders. TEM studies performed using quantitative metallography allowed to estimate mean grain size at 150 nm. HPT technique at the pressure of 5 GPa resulted in finest grain size as compared to other preparation techniques leading to nanoscale grain refinement in Ti samples. The mean crystal size was estimated at about 30 nm. (Abstract Copyright [2005], Wiley Periodicals, Inc.)
Energy Technology Data Exchange (ETDEWEB)
Semiatin, S.L.; Delo, D.P.; Shell, E.B.
2000-05-11
The effects of material constitutive behavior, tooling design, and friction conditions on metal flow, stress fields, and the tendency for tensile fracture during equal channel angular extrusion (ECAE) were established using a finite element modeling (FEM) technique. Three different material behaviors, typical of those encountered during cold and hot working, were investigated; these comprised (1) string hardening, (2) rigid, perfectly plastic, and (3) flow softening types of behavior. The tooling geometries consisted of a so-called simple design with no moving channel members and a complex design with a sliding bottom floor. The FEM results indicated that the most uniform flow was obtained during ECAE of a strain-hardening material having a low strain-rate sensitivity in tolling with a sharp inner corner (front leg) radius. The ECAE of materials with other constitutive behaviors or in tooling with a radiused front leg showed some degree of flow nonuniformity, even away from the head and tail of the extrusion. Tooling design and material properties were also predicted to have an important influence on the tensile stresses and hence tensile damage developed during ECAE. The FEM results were validated using visioplasticity and fracture observations for AISI 4340 steel and a near-gamma titanium aluminide alloy.
Mao, W. G.; Luo, J. M.; Dai, C. Y.; Shen, Y. G.
2015-05-01
The effect of thermal treatment on the elasto-plastic transition and mechanical properties of air plasma-sprayed 8 mol% Y2O3-stabilized ZrO2 (8YSZ) thermal barrier coatings was studied by nanoindentation test at ultra-low loads with a Berkovich indenter. The area contact function of the indenter was calibrated repeatedly under nano-scales, and the indenter tip radius was estimated under different indentation depths, respectively. Owing to the heterogeneous and porous microstructure, the scatter of all collected experimental data was analyzed by Weibull statistic method. It is interesting to observe that the hardness exhibits an apparent reverse indentation size effect under very small depths. The Young's modulus of 8YSZ varies with ranging from 213 to 246 GPa due to the sintering effect. True hardness of 8YSZ increases from as-received 72.9 GPa to a top value 79.7 GPa under 100 thermal cycles, and then slightly decreases from this value to 75.5 GPa under 175 thermal cycles. The pure elastic and elasto-plastic indentation curves were obtained by adjusting the indentation load magnitude. The elasto-plastic transition and resolved shear stress fields were discussed carefully from the use of energetic models and Hertzian contact theory.
International Nuclear Information System (INIS)
Repetitive hot deformation has been demonstrated as a new approach to obtain high-performance n-type bismuth–telluride-based alloys, benefiting from the deformation-induced lattice defects and texture enhancement. X-ray diffraction measurement showed that the oriented textures were greatly enhanced after repetitive hot deformation of the alloys with a quasi-layered crystal structure. The electrical conductivity was remarkably improved by the deformation-induced donor-like defect and texture enhancement, while the Seebeck coefficient remained almost unchanged, and consequently the room temperature power factor was significantly increased from 1.3 W m?1 K2, before hot deformation, to 2.9 W m?1 K2 after four hot deformations. The in-plane lattice thermal conductivity was also largely reduced by the generated high-density lattice defects during the hot-deformation process. The maximum ZT value for the repetitively hot-deformed samples reached 1.0 at 513 K, suggesting that the simple new top-down method is very promising for large-scale production of high-performance bismuth–telluride-based polycrystalline bulk materials.
We propose to study excited states in isotopes north-east of the doubly-magic $^{132}$Sn by $\\gamma$-ray spectroscopy following "safe" Coulomb excitation. The experiment aims to the determine B(E2) and B(E3) values to follow the evolution of quadrupole and octupole collectivity when going away from the shell closures at Z = 50 and N = 82. The B(E2; 0$^+_{gs}$ $\\rightarrow$ 2$^+_{1}$) values in the even isotopes $^{138-144}$Xe have been measured at REX-ISOLDE and the systematic trend towards neutron-rich nuclei is well described even by an empirical Grodzins-type formula. An increasing dipole moment observed for $^{140;142}$Xe is interpreted as indirect signature of increasing octupole correlations peaking at N = 88. So far, no B(E3) values are known. In contrast to the Xe isotopes, the Te ones, in particular $^{136}$Te, are known for their notoriously irregular behaviour. In order to understand the nuclear structure also on a microscopic basis, the isotope $^{136}$Te with just one pair of protons and neutrons...
2000-01-01
This document concerns the award of a contract for the supply of 168 MO superconducting octupole corrector magnet assemblies for the LHC. Following a market survey (MS-2594/LHC/LHC) carried out among 39 firms in thirteen Member States, two firms in Japan and one firm in the USA, a call for tenders (IT-2595/LHC/LHC) was sent on 15 February 2000 to 11 firms in seven Member States. By the closing date, CERN had received seven tenders. The Finance Committee is invited to agree to the negotiation of a contract with the firm ANTEC (ES), the lowest bidder, for the supply of 168 MO superconducting octupole corrector magnet assemblies for the LHC for a total amount of 2 075 935 Swiss francs, subject to revision for contractual deliveries after 31 December 2001, with an option for the supply of up to 50 additional MO corrector magnet assemblies, for a total amount of 526 400 Swiss francs, subject to revision for contractual deliveries after 31 December 2001, bringing the total amount to a maximum of 2 602 335 Swiss fra...
Energy Technology Data Exchange (ETDEWEB)
Hwang, J.K.; Hamilton, J.H.; Ramayya, A.V. [Vanderbilt University, Physics Department, Nashville, TN (United States)
2013-12-15
Excited high spin states in {sup 211}At, {sup 212}Rn, {sup 213}Fr and {sup 214}Ra with N = 126 are reorganized and interpreted in terms of the stretched weak coupling of an octupole 3{sup -} phonon. Nearly identical sequences of levels with {Delta}I = 3 and the parity change are found, for the first time, up to 25{sup -} for 20 states of {sup 214}Ra, up to 35{sup -} for 36 states of {sup 212}Rn and up to 53/2{sup +} for 16 states of {sup 213}Fr. The stretched weak coupling of an octupole phonon is extended up to the highest excitation energy of 11355 keV for {sup 212}Rn which has the largest experimental B(E3) value of 44.1(88) W.u. for the 11{sup -} {yields} 8{sub 2}{sup +} transition. The stretched weak coupling of an octupole 3{sup -} phonon needs to be considered when single particle configurations are assigned to high spin states. Average octupole excitation energies of 657(51) keV for {sup 211}At, 1101(28) keV for {sup 212}Rn, 667(25) keV for {sup 213}Fr, and 709(25) keV for {sup 214}Ra are obtained. The calculated level energies are in a good agreement with the experimental level energies within the error limit of 4.3%. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Regle, H.
1994-12-31
The ferritic oxide dispersion strengthened alloys are promising candidates for high temperature application materials, in particular for long life core components of advanced nuclear reactors. The aim of this work is to control the microstructure, in order to optimise the mechanical properties. The two ferritic alloys examined here, MA956 and MA957, are obtained by Mechanical Alloying techniques. They are characterised by quite anisotropic microstructure and mechanical properties. We have investigated the influence of hot and cold working processes (hot extrusion, swaging and cold-drawing) and recrystallization heat treatments on deformation textures, microstructures and tensile properties. The aim was to control the size of the grains and their anisotropic shape, using recrystallization heat treatments. After consolidation and hot extrusion, as-received materials present a extremely fine microstructure with elongated grains and a very strong (110) deformation texture with single-crystal character. At that stage of processing, recrystallization temperature are very high (1450 degrees C for MA957 alloy and 1350 degrees C for MA956 alloy) and materials develop millimetric recrystallized grains. Additional hot extrusion induce a fibre texture. Cold-drawing maintains a fibre texture, but the intensity decreases with increasing cold-work level. For both materials, the decrease of texture intensities correspond to a decrease of the recrystallization temperatures (from 1350 degrees C for a low cold-work level to 750 degrees C for 60 % cold-deformation, case of MA956 alloy) and a refinement of the grain size (from a millimetric size to less than an hundred of micrometer). Swaging develop a cyclic component where the intensity increases with increasing deformation in this case, the recrystallization temperature remains always very high and the millimetric grain size is slightly modified, even though cold-work level increases. (Abstract Truncated)
One-phonon octupole vibrational states in 136Xe, 137Cs, 138Ba, 140Ce and 142Nd with N = 82
International Nuclear Information System (INIS)
Excited high spin states in 136Xe, 137Cs, 138Ba, 140Ce and 142Nd with N = 82 are reorganized and interpreted in terms of the weak coupling mode of an octupole 3- phonon. Nearly identical sequences of levels with ?I = 3 and ?? = yes built on 17/2+ and 23/2- states are found, for the first time, up to 29/2+ and 35/2-, respectively, for 22 states of 137Cs. Also, nearly identical sequences of levels with ?I = 3 and ?? = yes built on the 6+ and 9- states are found, for the first time, up to 14+ and 17-, respectively, for 18 states of 136Xe, up to 14+ and 17-, respectively, for 24 states of 138Ba and up to 11+ and 14-, respectively, for 14 states of 140Ce. New spins and parities are assigned, tentatively, to the high spin states of these nuclei based on the weak coupling mode of an octupole 3- phonon. The weak coupling of an octupole 3- phonon needs to be considered when single particle configurations are assigned to high spin states. Neutron particle-hole states (?h11/2-1 f7/2+1) with weak coupling of an octupole 3- phonon are proposed, for the first time. The ?h11/2-1 f7/2+1 excitation energies (Eext(1p1h)) are nearly constant with increasing of Z. One-phonon excited states in 136Xe, 137Cs, 138Ba and 140Ce have the stretched weak coupling configurations of ?I = 3. But one-phonon excited states in 142Nd show the non-stretched weak coupling configurations of an octupole phonon with ?I = 3 and 2. (orig.)
Petrov, V. A.; Andreeva, O. V.; Poluektov, V. V.
2014-03-01
The development of vertical zoning of wall-rock metasomatic alteration is considered with the Mesozoic Strel'tsovka caldera as an example. This caldera hosts Russia's largest uranium ore field. Metasomatic rocks with the participation of various phyllosilicates, carbonates, albite, and zeolites are widespread in the ore field. In the eastern block of the caldera, where the main uranium reserves are accommodated, hydromica metasomatic alteration gives way to beresitization with depth. Argillic alteration, which is typical of the western block, is replaced with hydromica and beresite alteration only at a significant depth. Postore argillic alteration is superposed on beresitized rocks in the lower part of the section. Two styles of vertical metasomatic zoning are caused by different modes of deformation in the western and eastern parts of the caldera. Variations of the most important petrophysical properties of host rocks—density, apparent porosity, velocities of P- and S-waves, dynamic Young's modulus, and Poisson coefficient—have been determined by sonic testing of samples taken from different depths. It is suggested that downward migration of the brittle-ductile transition zone could have been a factor controlling facies diversity of metasomatic rocks. Such a migration was caused by a new phase of tectonothermal impact accompanied by an increase in the strain rate or by emplacement of a new portion of heated fluid. Transient subsidence of the brittle-ductile boundary increases the depth of the hydrodynamically open zone related to the Earth's surface and accelerates percolation of cold meteoric water to a greater depth. As a result, the temperature of the hydrothermal solution falls down, increasing the vertical extent of argillic alteration. High-grade uranium mineralization is also localized more deeply than elsewhere.
Milyukov, V.; Myasnikov, A.
2012-04-01
The Elbrus volcanic center is located on the northern slope of the main ridge of the Greater Caucasus. It includes Mount Elbrus, a double-top stratovolcano, and a number of small volcanic centers concentrated on its western flank. According to present understandings, the Elbrus volcano falls into the category of the so-called dormant volcanoes that become reactivated. It is a typical volcano of a continental type. During a number of years to study magmatic structures of the Elbrus volcano, their resonant properties and dynamics the new resonant method has been used. The idea of method is simple enough. Magmatic structures, being a resonator, upon incidence of a broadband powerful seismic signal generate the secondary seismic waves, having a set of resonant modes and containing information about physical and mechanical properties of structure inhomogeneities. These resonant modes are determined by geometrical parameters and elastic properties of the magma chamber as well as by magma properties. Estimation of the resonant parameters is based on the analysis of lithosphere deformations recorded by the wide-band Baksan laser interferometer-strainmeter with a 75-m armlength which is installed in the underground tunnel of the Baksan Neutrino Observatory, 20 km apart from Mt. Elbrus. Here we report the analysis of the teleseismic signals excited by seven mean-power earthquakes (the magnitude, as a rule, didn't exceed 6), that occurred within 2005-2010 in so-called "a near zone» of the volcano Elbrus (Elbrus resonant structures (magma chambers), at the same time, the energies of these moderate-power earthquakes are not enough to excite the free oscillations of the Earth. Spectral analysis revealed quite confidently 10 groups of resonance modes in the range of periods of 30 -150 s. In this group of the resonant modes, three modes are stand out with the periods of 62.1 s, 64.3 s, and 67.9 s, which are excited in 100% of seismic events. The intensities of these modes in the spectra are maximal, or close to the maximum. Estimates of Q-factor of the selected regional resonant modes lie in the range 250-300, that assumes that the revealed modes are generated by the structures containing magmatic fluids with a large gas component. The resonant parameters (frequencies and Q-factors of the resonant modes) we have found were interpreted in the framework of contemporary models of magma resonators. We estimated the depth and dimensions of the shallow magma chamber, as well as the properties of the magma fluid which are corroborated by available geological and geophysical evidence. Our interpretation of observational materials suggests that the intrachamber pressure seems to be rising owing to the advent of new portions of hot lava from a deep magma source. The stated approach provides a window to volcano dynamics and lays a foundation of the new "resonant" method for monitoring the state of volcano. This work is supported by the Russian Foundation for Basic Research.
Directory of Open Access Journals (Sweden)
Fernando Faria Correia
2013-10-01
Full Text Available PURPOSE: To study the deformation response of three distinct contact lenses with known structures, which served as corneal models, under different chamber pressures using ultra-high-speed (UHS Scheimpflug imaging. METHODS: Three hydrophilic contact lenses were mounted on a sealed water chamber with precisely adjustable pressure: TAN-G5X (41% hydroxyethylmethacrylate/glycolmethacrylate, 550 µm thick, TAN-40 (62% hydroxyethylmethacrylate, 525 µm thick and TAN-58 (42% methylmethacrylate, 258 µm thick. Each model was tested five times under different pressures (5, 15, 25, 35 and 45 mmHg, using ultra-high-speed Scheimpflug imaging during non-contact tonometry. 140 Scheimpflug images were taken with the UHS camera in each measurement. The deformation amplitude during non-contact tonometry was determined as the highest displacement of the apex at the highest concavity (HC moment. RESULTS: At each pressure level, the deformation amplitude was statistically different for each lens tested (p<0.001, ANOVA. Each lens had different deformation amplitudes under different pressure levels (p<0.001; Bonferroni post-hoc test. The thicker lens with less polymer (TAN-G5X had a higher deformation (less stiff behavior than the one that was thinner but with more polymer (TAN-40, when measured at the same internal pressure. The thinnest lens with less polymers (TAN-58 had a lower deformation amplitude (stiffer behavior at higher pressures than the thicker ones with more polymer (TAN-40 and TAN-G5X at lower pressures. CONCLUSIONS: UHS Scheimpflug imaging allowed for biomechanical assessment through deformation characterization of corneal models. Biomechanical behavior was more influenced by material composition than by thickness. Chamber pressure had a significant impact on deformation response of each lens.
The deformed exponential functions of two variables
Stankovi?, Miomir S.; Marinkovi?, Sladjana D.; Rajkovi?, Predrag M.
2010-01-01
In the recent development in a various disciplines of physics, it is noted the need for including the deformed versions of the exponential functions. In this paper, we consider the deformations which have two purposes: to have them like special cases, and, even more, to acquit their inauguration from mathematical point of view. Really, we will show interesting differential and difference properties of our deformations which are important in forming and explanation of continu...
The deformed exponential functions of two variables
Stankovi?, Miomir S; Rajkovi?, Predrag M
2010-01-01
In the recent development in a various disciplines of physics, it is noted the need for including the deformed versions of the exponential functions. In this paper, we consider the deformations which have two purposes: to have them like special cases, and, even more, to acquit their inauguration from mathematical point of view. Really, we will show interesting differential and difference properties of our deformations which are important in forming and explanation of continuous and discrete models of numerous phenomena.
Deformed aerogels in the superfluid 3He
Fomin, I. A.; Surovtsev, E. V.
2015-01-01
Deformed aerogels induce a global anisotropy in the superfluid 3He and orient the orbital part of its order parameter. Here a phenomenological theory of the orientational effect of elastic deformations of aerogels on the superfluid phases of 3He in the spirit of conventional theory of elasticity is formulated. Phenomenological coefficients, entering basic relations, depend on properties of given aerogel in the non-deformed state. Examples of originally isotropic silica aerog...
International Nuclear Information System (INIS)
A metastable ?-Ti alloy, Ti–10V–3Fe–3Al (wt.%), was subjected to thermomechanical processing (TMP), where the temperature of isothermal holding in the ? + ? phase field was varied in order to change the volume fraction of the ? phase and, correspondingly, the ? phase stability. Following TMP, compression tests were performed at room temperature to evaluate the deformation mode. Microstructural features induced by compression were identified using transmission electron microscopy. It was found that {3 3 2}?1 1 3?? deformation twinning along with stress-induced products (?? martensite and ? lamellae) and slip were operational in the least stable ?. The co-existence of {3 3 2}?1 1 3?? and {1 1 2}?1 1 1?? twinning was found at intermediate ? stability along with other deformation products. With further increasing of ? phase stability, no {3 3 2}?1 1 3?? twinning was detected whereas other deformation modes remained unchanged. In stable ? phase, dislocation glide was the only deformation mode to be found. It was revealed that triggering stress required inducing the deformation products increases with the ? phase stability. Based on the findings, a modification of the lower portion of the Bo?–Md? phase stability diagram is proposed
?-deformed gauge theory and ?-deformed gravity
International Nuclear Information System (INIS)
Noncommutative (deformed, quantum) spaces are deformations of the usual commutative space-time. They depend on parameters, such that for certain values of parameters they become the usual space-time. The symmetry acting on them is given in terms of a deformed quantum group symmetry. In this work we discuss two special examples, the ?-deformed space and the ?-deformed space. In the case of the ?-deformed space we construct a deformed theory of gravity. In the first step the deformed diffeomorphism symmetry is introduced. It is given in terms of the Hopf algebra of deformed diffeomorphisms. The algebra structure is unchanged (as compared to the commutative diffeomorphism symmetry), but the comultiplication changes. In the commutative limit we obtain the Hopf algebra of undeformed diffeomorphisms. Based on this deformed symmetry a covariant tensor calculus is constructed and concepts such as metric, covariant derivative, curvature and torsion are defined. An action that is invariant under the deformed diffeomorphisms is constructed. In the zeroth order in the deformation parameter it reduces to the commutative Einstein-Hilbert action while in higher orders correction terms appear. They are given in terms of the commutative fields (metric, vierbein) and the deformation parameter enters as the coupling constant. One special example of this deformed symmetry, the ?-deformed global Poincar e symmetry, is also discussed. In the case of the ?-deformed space our aim is the construction of noncommutative gauge theories. Starting from the algebraic definition of the ?-deformed space, derivatives and the deformed Lorentz generators are introduced. Choosing one particular set of derivatives, the ?-Poincar e Hopf algebra is defined. The algebraic setting is then mapped to the space of commuting coordinates. In the next step, using the enveloping algebra approach and the Seiberg-Witten map, a general nonabelian gauge theory on this deformed space is constructed. As a consequence of the deformed Leibniz rules for the derivatives used in the construction, the gauge field is derivative-valued. As in the ?-deformed case, in the zeroth order of the deformation parameter the theory reduces to its commutative analog and the higher order corrections are given in terms of the usual (commutative) fields. In this way the field content of the theory is unchanged, but new interactions appear. The deformation parameter takes the role of the coupling constant. For the special case of U(1) gauge theory the action for the gauge field coupled to fermionic matter is formulated and the equations of motion and the conserved current(s) are calculated. The ambiguities in the Seiberg-Witten map are discussed and partially fixed, and an effective action (up to first order in the deformation parameter) which is invariant under the usual Poincar e symmetry is obtained. (Orig.)
Plastic deformation mechanism in Mg--2%Be
Energy Technology Data Exchange (ETDEWEB)
Haslingerova, I.; Saxl, I.; Cech, B.
1973-09-01
Results of tensile tests in the range 20 to 500 deg C on magnesium composite rods are described. After mechanical treatment and recrystallization, a pronounced texture was discovered. Deformation mechanism and its relation to the preferred orientation were investigated. Mechanical properties were found to be affected by working and recrystallization textures. Nonbasal slip is proposed as the major operating deformation mechanism. (auth)
Bojowald, Martin; Paily, George M.
2012-01-01
Deformed special relativity is embedded in deformed general relativity using the methods of canonical relativity and loop quantum gravity. Phase-space dependent deformations of symmetry algebras then appear, which in some regimes can be rewritten as non-linear Poincare algebras with momentum-dependent deformations of commutators between boosts and time translations. In contrast to deformed special relativity, the deformations are derived for generators with an unambiguous ph...
Properties of the distorted Kerr black hole
Abdolrahimi, Shohreh; Nedkova, Petya; Tzounis, Christos
2015-01-01
We investigate the properties of the ergoregion and the location of the curvature singularities for the Kerr black hole distorted by the gravitational field of external sources. The particular cases of quadrupole and octupole distortion are studied in detail. We also investigate the scalar curvature invariants of the horizon and compare their behaviour with the case of the isolated Kerr black hole. In a certain region of the parameter space the ergoregion consists of a compact region encompassing the horizon and a disconnected part extending to infinity. The curvature singularities in the domain of outer communication, when they exist, are always located on the boundary of the ergoregion. We present arguments that they do not lie on the compact ergosurface. For quadrupole distortion the compact ergoregion size is negatively correlated with the horizon angular momentum when the external sources are varied. For octupole distortion infinitely many ergoregion configurations can exist for a certain horizon angular...
Developing a Virtual Rock Deformation Laboratory
Zhu, W.; Ougier-simonin, A.; Lisabeth, H. P.; Banker, J. S.
2012-12-01
Experimental rock physics plays an important role in advancing earthquake research. Despite its importance in geophysics, reservoir engineering, waste deposits and energy resources, most geology departments in U.S. universities don't have rock deformation facilities. A virtual deformation laboratory can serve as an efficient tool to help geology students naturally and internationally learn about rock deformation. Working with computer science engineers, we built a virtual deformation laboratory that aims at fostering user interaction to facilitate classroom and outreach teaching and learning. The virtual lab is built to center around a triaxial deformation apparatus in which laboratory measurements of mechanical and transport properties such as stress, axial and radial strains, acoustic emission activities, wave velocities, and permeability are demonstrated. A student user can create her avatar to enter the virtual lab. In the virtual lab, the avatar can browse and choose among various rock samples, determine the testing conditions (pressure, temperature, strain rate, loading paths), then operate the virtual deformation machine to observe how deformation changes physical properties of rocks. Actual experimental results on the mechanical, frictional, sonic, acoustic and transport properties of different rocks at different conditions are compiled. The data acquisition system in the virtual lab is linked to the complied experimental data. Structural and microstructural images of deformed rocks are up-loaded and linked to different deformation tests. The integration of the microstructural image and the deformation data allows the student to visualize how forces reshape the structure of the rock and change the physical properties. The virtual lab is built using the Game Engine. The geological background, outstanding questions related to the geological environment, and physical and mechanical concepts associated with the problem will be illustrated on the web portal. In addition, some web based data collection tools are available to collect student feedback and opinions on their learning experience. The virtual laboratory is designed to be an online education tool that facilitates interactive learning.; Virtual Deformation Laboratory
Ultrasonic plastic deformation of steels
Zaitsev, K.; Klimenov, V.; Loshchilova, M.; Polovnikov, C.
2015-09-01
In the work we demonstrate the possibility of forming thin surface and near-surface layers with submicrocrystalline structure under ultrasonic plastic deformation of machined steels. Formation of fine gradient textures up to nanocrystalline allows significant changing physical and mechanical properties of machined steels. Ensures improvement of microstructure, produces internal compressive strains which improves the cyclic strength of machine parts.
International Nuclear Information System (INIS)
Severe plastic deformation via equal-channel angular pressing was shown to induce characteristic ultra-fast diffusion paths in Ni (Divinski et al., 2011). The effect of heat treatment on these paths, which were found to be represented by deformation-modified general high-angle grain boundaries (GBs), is investigated by accurate radiotracer self-diffusion measurements applying the 63Ni isotope. Redistribution of free volume and segregation of residual impurities caused by the heat treatment triggers relaxation of the diffusion paths. A correlation between the GB diffusion kinetics, internal friction, microstructure evolution and microhardness changes is established and analyzed in detail. A phenomenological model of diffusion enhancement in deformation-modified GBs is proposed
Deformations of three-dimensional metrics
Pugliese, Daniela; Stornaiolo, Cosimo
2015-03-01
We examine three-dimensional metric deformations based on a tetrad transformation through the action the matrices of scalar field. We describe by this approach to deformation the results obtained by Coll et al. (Gen. Relativ. Gravit. 34:269, 2002), where it is stated that any three-dimensional metric was locally obtained as a deformation of a constant curvature metric parameterized by a 2-form. To this aim, we construct the corresponding deforming matrices and provide their classification according to the properties of the scalar and of the vector used in Coll et al. (Gen Relativ Gravit 34:269, 2002) to deform the initial metric. The resulting causal structure of the deformed geometries is examined, too. Finally we apply our results to a spherically symmetric three geometry and to a space sector of Kerr metric.
International Nuclear Information System (INIS)
Preforms made by filling silver tubes with YBa2Cu3O7-x (YBCO) powder were drawn to obtain wires with diameters in the 0.25mm to 1.00mm range. Straight samples of these wires were sintered and oxygenated. The observed changes in Tc and Jc while the samples were thermally cycled or mechanically deformed are reported
Singh, Alok K; Natarajan, Vasant
2015-01-01
We measure hyperfine structure in the metastable ${^3P}_2$ state of $^{173}$Yb and extract the nuclear magnetic octupole moment. We populate the state using dipole-allowed transitions through the ${^3P}_1$ and ${^3S}_1$ states. We measure frequencies of hyperfine transitions of the ${^3P}_2 \\rightarrow {^3S}_1$ line at 770 nm using a Rb-stabilized ring cavity resonator with a precision of 200 kHz. Second-order corrections due to perturbations from the nearby ${^3P}_1$ and ${^1P}_1$ states are below 30 kHz. We obtain the hyperfine coefficients as: $A=-742.11(2)$ MHz, $B=1339.2(2)$ MHz, which represent two orders-of-magnitude improvement in precision, and $C=0.54(2)$ MHz. From atomic structure calculations, we obtain the nuclear moments: quadrupole $Q=2.46(12)$ b and octupole $\\Omega=-34.4(21)$ b\\,$\\times \\mu_N$.
International Nuclear Information System (INIS)
The interrelation between the octupole phonon and the low-lying proton-neutron mixed-symmetry quadrupole in near-spherical nuclei is investigated. The one-phonon states decay by collective E3 and E2 transitions to the ground state and by relatively strong E1 and M1 transitions to the isoscalar 2+1 state. We apply the proton-neutron version of the Interacting Boson Model including quadrupole and octupole bosons (sdf-IBM-2). Two F-spin symmetric dynamical symmetry limits of the model, namely the vibrational and the ?-unstable ones, are considered. We derived analytical formulae for excitation energies as well as B(E1), B(M1), B(E2), and B(E3) values for a number of transitions between low-lying states. The model well reproduces many known transition strengths in the near spherical nuclei 142Ce and 94Mo. (authors)
Geometric Total Variation for Texture Deformation
DEFF Research Database (Denmark)
Bespalov, Dmitriy; Dahl, Anders Lindbjerg
2010-01-01
In this work we propose a novel variational method that we intend to use for estimating non-rigid texture deformation. The method is able to capture variation in grayscale images with respect to the geometry of its features. Our experimental evaluations demonstrate that accounting for geometry of features in texture images leads to significant improvements in localization of these features, when textures undergo geometrical transformations. Accurate localization of features in the presense of unkown deformations is a crucial property for texture characterization methods, and we intend to expoit this property for estimation of non-rigid deformations in our future work.
Kourov, N. I.; Pushin, V. G.; Korolev, A. V.; Marchenkov, V. V.; Marchenkova, E. B.; Kazantsev, V. A.; Weber, H. W.
2011-01-01
The effect of one-percent substitution of iron for manganese on the physical (magnetic, electrical, thermal, and galvanomagnetic) properties and the crystal structure of the Ni54Mn21Ga25 alloy has been investigated. It has been demonstrated that the deviation of the alloy composition from the stoichiometric composition Ni50Mn25Ga25 leads to the formation of a mixed ferromagnetic-antiferromagnetic state. The atomic disordering and nanostructuring of the alloys under investigation due to the severe plastic deformation by torsion in Bridgman anvils to sizes of 10-20 nm result in the suppression of reversible magnetically controlled shape memory effects.
Kanada-Enyo, Y
2005-01-01
Systematic analysis of deformations in neutron-rich N=14 isotones was done based on the method of antisymmetrized molecular dynamics. The property of the shape coexistence in $^{28}$Si, which is known to have the oblate ground state and the prolate excited states, was successfully described. The results suggest that the shape coexistence may occur also in neutron-rich N=14 nuclei as well as $^{28}$Si. It was found that the oblate neutron shapes are favored because of the spin-orbit force in most of N=14 isotones. $Q$ moments and $E2$ transition strengths in the neutron-rich nuclei were discussed in relation to the intrinsic deformations, and a possible difference between the proton and neutron deformations in $^{24}$Ne was proposed.
Plastic deformation: Shearing mountains atom by atom
Energy Technology Data Exchange (ETDEWEB)
Müllner, Peter, E-mail: petermullner@boisestate.edu [Department of Materials Science and Engineering, Boise State University, Boise, ID 83725 (United States)
2013-11-15
Highlights: ? Rocks, wood, ceramics, semiconductors, and metals all deform in the same way, namely by heterogeneous shear banding via hierarchical orthogonal shear modes. ? While the governing principles of deformation are the same for rocks, wood, ceramics, semiconductors, and metals, these materialsdiffer in their microscopic deformation mechanisms and in the width of the shear band, which covers twelve orders of magnitude from angstroms to hundreds of meters. ? Microscopic deformation mechanisms couple to macroscopic deformation mechanisms, i.e. shear banding, through the collective properties of defect groups on the mesoscale. -- Abstract: Conventional wisdom established atomistic defects, dislocations, as agents of plastic deformation. On macroscopic scale, rock, wood, steel, tough ceramics, fiber reinforced composites, and silicon all deform in the same way and produce the same pattern; shear bands. The argumentation presented here, starts on the largest length scale of the problem at hand and leads through a number of hierarchical levels down to the atomistic mechanism. Shear bands develop discontinuously by the motion of a process zone. Locally, i.e. in the process zone, deformation proceeds perpendicularly to the macroscopic shear, in combination with a rotation. The microscopic shear itself may occur again in a discontinuous manner and again orthogonally to the intermediate level and so on at ever smaller scale. Material properties come into play at the highest hierarchical level, i.e. at the smallest length scale where they control the well-known micromechanisms.
Shimizu, Yousuke; Tomota, Yo; Onuki, Jin; Khoo, Khyou Pin; Kurosu, Toshiki
2009-06-01
The deformation behaviors of Al-Si films and the strength change of Al wire bonds on Al-Si films during heating and cooling cycles have been investigated as a function of substrate temperature of the sputtering process; the purpose was to clarify reliability of both Al wire bonds and Al-Si films for use in insulated gate bipolar transistor (IGBT) modules. The extent of deformation in Al-Si films sputtered at 593 K during heating and cooling cycles was the smallest among films sputtered at room temperature (RT), 473 K, and 593 K. The strength of Al wire bonds on Al-Si films sputtered at the three temperatures was the highest for Al-Si films sputtered at 593 K. The reliability of Al wire bonds on Al-Si films formed at 593 K was about two times higher than the bond reliability on Al-Si films formed at RT and 473 K.
International Nuclear Information System (INIS)
In the development, by the method of mechanical and heat treatment, of strenghening conditions for tubes from steel 12Kh1MF cold drawing and cold reducing are used at a uniform deformation factor of 11% but with materially different schemes of stress-strain state (different distributions and signs of strains and stresses). The greatest strenthening effect as regards to the ultimate stress and yield stress at a uniform deformation is obtained in the drawing. The poligonizing annealing makes for the levelling out of the drawn and reduced metal, the strength characteristics deteriorate to a greater degree for the drawn metal. The heat resisting characteristics of metal of drawn and reduced tubes at a test temperature of 540degC and high stresses (20-24kgs/mm2) are similar, the plasticity, however, being higher with then drawn tubes. At stresses close to the working ones, metal of the reduced tubes features longer time periods before failure. (author)
International Nuclear Information System (INIS)
Investigations performed under conditions of uniaxial tension have shown that the values of proof stress and elongation of N26J2T3Nb steel with an initially metastable austenitic structure diminish when the deformation temperature approaches the M4 temperature which, in turn, is lowered with the increasing deformation rate. The increase in stability of austenite, resulting from strain hardening as well as from a decrease in activity of twin boundaries which act as sources of martensitic shear, leads gradually to the confinement of the strain-induced martensitic transformation to slip bands. it has been shown that it is not be twin mechanism of the strain-induced transformation, but is mainly responsible for the integranular cracking and decrease in the ductility of the steel. (author). 26 refs, 9 figs, 1 tab
Energy Technology Data Exchange (ETDEWEB)
Hwang, J.K.; Hamilton, J.H.; Ramayya, A.V. [Vanderbilt University, Physics Department, Nashville, TN (United States)
2013-10-15
Excited high spin states in {sup 136}Xe, {sup 137}Cs, {sup 138}Ba, {sup 140}Ce and {sup 142}Nd with N = 82 are reorganized and interpreted in terms of the weak coupling mode of an octupole 3{sup -} phonon. Nearly identical sequences of levels with {Delta}I = 3 and {Delta}{pi} = yes built on 17/2{sup +} and 23/2{sup -} states are found, for the first time, up to 29/2{sup +} and 35/2{sup -}, respectively, for 22 states of {sup 137}Cs. Also, nearly identical sequences of levels with {Delta}I = 3 and {Delta}{pi} = yes built on the 6{sup +} and 9{sup -} states are found, for the first time, up to 14{sup +} and 17{sup -}, respectively, for 18 states of {sup 136}Xe, up to 14{sup +} and 17{sup -}, respectively, for 24 states of {sup 138}Ba and up to 11{sup +} and 14{sup -}, respectively, for 14 states of {sup 140}Ce. New spins and parities are assigned, tentatively, to the high spin states of these nuclei based on the weak coupling mode of an octupole 3{sup -} phonon. The weak coupling of an octupole 3{sup -} phonon needs to be considered when single particle configurations are assigned to high spin states. Neutron particle-hole states ({nu}h{sub 11/2} {sup -1} f{sub 7/2} {sup +1}) with weak coupling of an octupole 3{sup -} phonon are proposed, for the first time. The {nu}h{sub 11/2} {sup -1} f{sub 7/2} {sup +1} excitation energies (E{sub ext}(1p1h)) are nearly constant with increasing of Z. One-phonon excited states in {sup 136}Xe, {sup 137}Cs, {sup 138}Ba and {sup 140}Ce have the stretched weak coupling configurations of {Delta}I = 3. But one-phonon excited states in {sup 142}Nd show the non-stretched weak coupling configurations of an octupole phonon with {Delta}I = 3 and 2. (orig.)
Shell structures and chaos in deformed nuclei and large metallic clusters
Heiss, W D; Radu, S; Heiss, W D; Nazmitdinov, R G; Radu, S
1994-01-01
A reflection-asymmetric deformed oscillator potential is analysed from the classical and quantum mechanical point of view. The connection between occurrence of shell structures and classical periodic orbits is studied using the ''removal of resonances method'' in a classical analysis. In this approximation, the effective single particle potential becomes separable and the frequencies of the classical trajectories are easily determined. It turns out that the winding numbers calculated in this way are in good agreement with the ones found from the corresponding quantum mechanical spectrum using the particle number dependence of the fluctuating part of the total energy. When the octupole term is switched on it is found that prolate shapes are stable against chaos whereas spherical and oblate cases become chaotic. An attempt is made to explain this difference in the quantum mechanical context by looking at the distribution of exceptional points which results from the matrix structure of the respective Hamiltonian...
Feldman, Hume A; Hudson, Michael J
2009-01-01
The low order moments of the large scale peculiar velocity field are sensitive probes of the matter density fluctuations on very large scales. However, peculiar velocity surveys have varying spatial distributions of tracers, and so the moments estimated are hard to model and thus are not directly comparable between surveys. In addition, the sparseness of typical proper distance surveys can lead to aliasing of small scale power into what is meant to be a probe of the largest scales. Here we extend our previous optimization analysis of the bulk flow to include the shear and octupole moments where velocities are weighted to give an optimal estimate of the moments of an idealized survey, with the variance of the difference between the estimate and the actual flow being minimized. These "minimum variance" (MV) estimates can be designed to calculate the moments on a particular scale with minimal sensitivity to small scale power, and thus different surveys can be directly compared. The MV moments were also designed ...
Deformations of crystal frameworks
Borcea, Ciprian S.; Streinu, Ileana
2011-01-01
We apply our deformation theory of periodic bar-and-joint frameworks to tetrahedral crystal structures. The deformation space is investigated in detail for frameworks modelled on quartz, cristobalite and tridymite.
Deformations of chiral algebras
Tamarkin, Dimitri
2003-01-01
We start studying chiral algebras (as defined by A. Beilinson and V. Drinfeld) from the point of view of deformation theory. First, we define the notion of deformation of a chiral algebra on a smooth curve $X$ over a bundle of local artinian commutative algebras on $X$ equipped with a flat connection (whereas `usual' algebraic structures are deformed over a local artinian algebra) and we show that such deformations are controlled by a certain *-Lie algebra $\\mathfrak g$. The...
Totonchi, Ali; Guyuron, Bahman
2016-01-01
The alar rim plays an important role in nasal harmony. Alar rim flaws are common following the initial rhinoplasty. Classification of the deformities helps with diagnosis and successful surgical correction. Diagnosis of the deformity requires careful observation of the computerized or life-sized photographs. Techniques for treatment of these deformities can easily be learned with attention to detail. PMID:26616701
PT-symmetrically deformed shock waves
International Nuclear Information System (INIS)
We investigate for a large class of nonlinear wave equations, which allow for shock wave formations, how these solutions behave when they are PT-symmetrically deformed. For real solutions we find that they are transformed into peaked solutions with a discontinuity in the first derivative instead. The systems we investigate include the PT-symmetrically deformed inviscid Burgers equation recently studied by Bender and Feinberg, for which we show that it does not develop any shocks, but peaks instead. In this case we exploit the rare fact that the PT-deformation can be provided by an explicit map found by Curtright and Fairlie together with the property that the undeformed equation can be solved by the method of characteristics. We generalise the map and observe this type of behaviour for all integer values of the deformation parameter ?. The peaks are formed as a result of mapping the multi-valued self-avoiding shock profile to a multi-valued self-crossing function by means of the PT-deformation. For some deformation parameters we also investigate the deformation of complex solutions and demonstrate that in this case the deformation mechanism leads to discontinuities. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Quantum physics with non-Hermitian operators’. (paper)
Deformed aerogels in the superfluid 3He
Fomin, I. A.; Surovtsev, E. V.
2015-08-01
Deformed aerogels induce a global anisotropy in the superfluid 3He and orient the orbital part of its order parameter. Here a phenomenological theory of the orientational effect of elastic deformations of aerogels on the superfluid phases of 3He in the spirit of conventional theory of elasticity is formulated. Phenomenological coefficients, entering basic relations, depend on properties of given aerogel in the nondeformed state. Examples of originally isotropic silica aerogel and axially symmetric "nematically ordered" aerogel are considered. Values of phenomenological coefficients are estimated with the aid of a simple microscopic model. An example of a nonuniform deformation of nematically ordered aerogel is discussed.
Thermal conductivity of deformed carbon nanotubes
Zhong, Wei-Rong; Zhang, Mao-Ping; Zheng, Dong-Qin; Ai, Bao-Quan
2011-01-01
We investigate the thermal conductivity of four types of deformed carbon nanotubes by using the nonequilibrium molecular dynamics method. It is reported that various deformations have different influence on the thermal properties of carbon nanotubes. For the bending carbon nanotubes, the thermal conductivity is independent on the bending angle. However, the thermal conductivity increases lightly with XY-distortion and decreases rapidly with Z-distortion. The thermal conducti...
A study of collective octupole states in barium in the interacting boson model
International Nuclear Information System (INIS)
We analyze low-lying collective negative parity states in 140-148Ba in terms of the interacting spdf boson model. We point out the crucial role played by p boson in describing E1 transitions. We discuss the rather unusual properties of the nucleus 146Ba. (orig.)
Deformations in quantum mechanics
International Nuclear Information System (INIS)
We consider deformations of quantum mechanical objects, and use the novel construction of warped convolutions for deformation. It turns out that through the deformation we are able to obtain several quantum mechanical effects where electromagnetic fields play a role. We understand the magnetic field as an object which is the outcome of strict mathematical deformation. Furthermore, we are able to obtain all magnetic fields by using this method of deformation. The results are used in quantum field theory to obtain an effective quantum plane.
Deformations in quantum physics
International Nuclear Information System (INIS)
We consider deformations of quantum mechanical objects, and use the novel construction of warped convolutions for deformation. It turns out that through the deformation we are able to obtain several quantum mechanical effects where electromagnetic fields play a role. We understand the magnetic field as an object which is the outcome of strict mathematical deformation. Furthermore, we are able to obtain all magnetic fields by using this method of deformation. The results are used in quantum field theory to obtain an effective quantum plane.
Konc, Z.; Garrido, C.; Tommasi, A.; Padrón-Navarta, J.; Hidas, K.; Szabo, C.
2011-12-01
The volcanic activity in the SE Iberian Volcanic Province is the surface expression of magmatism in a complex geodynamic setting during the Cenozoic development of a Mediterranean-type back-arc basin in the Alboran realm. The late stage of this geodynamical evolution was characterized by Neogene alkaline basalt volcanism erupted at 2-3 Ma in the Tallante and Los Perez (Murcia) volcanic centers. This volcanism entrained numerous mantle xenoliths that provide a snapshot of the structure and composition of the lithospheric mantle beneath this region. Xenoliths are spinel (± plagioclase ± amphibole) lherzolite, and minor harzburgite and wehrlite showing porphyroclastic to fine- to medium-grained granoblastic textures. Mantle xenoliths display a marked olivine crystal preferred orientation (CPO) that is similar in the two investigated volcanic centers. The dominant olivine CPO is [100]-fiber pattern characterized by a strong alignment of olivine [100] axes near or parallel to the peridotite lineation and a girdle distribution of [010] axes with a maximum normal to the peridotite foliation. This CPO is consistent with dominant activation of the high temperature [100]{0kl} slip systems of olivine and suggests simple shear or combinations of simple shear and pure shear with a transtensional component were the dominant deformation regimes. These olivine CPO contrast with those of Ronda peridotite -sampling the lithospheric mantle of the Alboran domain at 23 Ma- which are consistent with a transpressional deformation regime, indicating a temporal evolution of the deformation regime to transpressive to a transtensive in the Miocene. The seismic anisotropy calculated from xenolith's CPO and modal compositions is characterized by fast propagation of P-waves and polarization of fast S-waves parallel to the lineation. Highest delay times are observed for S-waves propagating within the foliation, but at high angle to the lineation, whereas S-waves propagating along the lineation sample an apparent isotropy direction. Based on these data, we interpret the recent SKS splitting measurements in the western Mediterranean as indicating dominant belt-parallel flow in the mantle beneath the Betic Cordillera.
International Nuclear Information System (INIS)
Long-term creep rupture strengths and the microstructural stability of ASME P92 and P122 pipes have been studied using creep testing at the temperatures from 550 to 700 deg. C and detailed scanning transmission electron microscopy. Creep rupture strength of P92 is found to be more stable than that of P122 at temperatures over 600 deg. C, which is mainly due to the difference in their Cr content. P122 type model steel with reduced Cr content, 9%Cr, has been prepared to explore the effect of Cr on the stability of MX and formation of Z-phase during creep deformation. MX in 9%Cr steel is found to be stable even after prolonged exposure at 650 deg. C, while Cr and Fe concentration to MX without marked coarsening has been observed in 10.5%Cr steel after aging for 10,000 h at 650 deg. C. This seems to lead to the transition of MX carbonitride into the Z-phase after aging for 23,000 h, which requires ordering in a M2N lattice to achieve a tetragonal Z-phase to be stable. Creep deformation behavior in the transient creep region of the steels is almost same up to about 7000 h, while in the acceleration creep region the creep rate of 10.5%Cr steel becomes much faster than that of 9%Cr steel, resulting in shorter rupture life. It is obvious that the creep rupture strength degradation starts prior to the formation of Z-phase in 10.5%Cr steel. It is thus concluded that Z-phase is not a necessary factor for degradation of creep rupture strength but the instability of the fine precipitates such as Cr2(C, N) caused by the compositions change like Cr supply to MX carbonitride is more essential.
We propose to exploit the unique capability of ISOLDE to provide intense post-accelerated $^{144}$Ba ion beams from the REX facility to enable the Coulomb excitation of the first 3 $^{-}$ state in this nucleus. By measuring the $\\gamma$-ray yields of the E1 decay connecting the 3$^{-}$ and 2$^{+}$ states using the MINIBALL array, we can obtain the interesting transition matrix element. The result will give quantitative information about octupole correlations in this nucleus. We require 27 shifts to fulfil the aims of the experiment. Requested shifts:
Energy Technology Data Exchange (ETDEWEB)
Trabert, E; Beiersdorfer, P; Brown, G V
2006-12-21
We present measurements of high statistical significance of the rate of the magnetic octupole (M3) decay in nickel-like ions of isotopically pure {sup 129}Xe and {sup 132}Xe. On {sup 132}Xe, an isotope with zero nuclear spin and therefore without hyperfine structure, the lifetime of the metastable level was established as (15.06 {+-} 0.24) ms. On {sup 129}Xe, an additional fast (2.7 {+-} 0.1 ms) decay component was established that represents hyperfine mixing with a level that decays by electric quadrupole (E2) radiation.
The ?h11/2-1?i13/2-2 three-hole isomeric state and octupole core excitation in the 205Tl nucleus
International Nuclear Information System (INIS)
New high-spin states were identified in the 205Tl isotope produced in deep-inelastic heavy-ion reactions. The expected 29/2+ yrast state and 35/2- isomeric state with 235 ns half-life were located above the 2.6 ?s isomer known from previous studies. Above this isomer a 7092 keV level was interpreted as a 41/2+ state arising from the coupling of the octupole vibration of the 208Pb core with the three-hole structure of the 35/2- isomer. (orig.)
We propose to exploit the unique capability of ISOLDE to provide intense post-accelerated $^{142}$Ba and $^{144}$Ba ion beams from the HIE-ISOLDE facility to enable the Coulomb excitation of the first 3$^-$ state in these nuclei. By measuring the $\\gamma$-ray yields of the E1 decays from the 3$^-$ state using the MINIBALL array, we can obtain the interesting transition matrix element. The results will give quantitative information about octupole correlations in these nuclei. We require 33 shifts to fulfil the aims of the experiment.
Review of Deformable Curves-A Retro Analysis
Directory of Open Access Journals (Sweden)
A. Prabhu Britto
2007-01-01
Full Text Available This study reviews Deformable curves (Active contours. The main strength of Deformable curves stems from their capability to provide to humans or higher processes, several interpretations of image data by supporting interactive mechanisms. Deformable curves offer a unique and powerful approach to segmentation. They are capable of accommodating variability of biological structures. The objective of this study is to study the frameworks of different active contour models, classify the methods according to several properties and compare their properties. This study is expected to yield a very good insight into Deformable curves.
Energy Technology Data Exchange (ETDEWEB)
Follin, Sven (SF GeoLogic AB (Sweden)); Stigsson, Martin (Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)); Rhen, Ingvar (Sweco Environment AB (Sweden)); Engstroem, Jon (Geologian tutkimuskeskus (Finland)); Klint, Knut Erik (De Nationale Geologiske Undersoegelser for Danmark og Groenland (Denmark))
2011-05-15
The database of the GAP site is under development. In order to meet the data needs of the different modelling teams working with groundwater flow modelling it has been decided to compile trial data sets comprising structural-hydraulic properties suitable for flow modelling on different scales. The properties provided in this report are based on data and groundwater flow modelling studies conducted for three sites located in the Fennoscandian Shield, two of which are studied by SKB, Forsmark and Laxemar, and one by Posiva, Olkiluoto. The provided hydraulic properties provided here are simplified to facilitate a readily usage together with the GAP Geomodel version 1.
Finite Element Analysis of Deformation of Saturated Soft Clay Foundation in Axisymmetric State
Xin Yan-Shao; Xian Zhang-Ling; Dong Ling-Liang
2013-01-01
Analysis of foundation deformation is an important part in geotechnical engineering research field. Saturated soft clay has the property of high compressibility and low permeability, therefore it has great academic value and application value to improve the method analyzing deformation of soft clay foundation. In this study, through analyzing the deformation mechanism of soft clay foundation, the interrelation of instantaneous deformation and consolidation deformation of saturated soft clay f...
Performance through Deformation and Instability
Bertoldi, Katia
2015-03-01
Materials capable of undergoing large deformations like elastomers and gels are ubiquitous in daily life and nature. An exciting field of engineering is emerging that uses these compliant materials to design active devices, such as actuators, adaptive optical systems and self-regulating fluidics. Compliant structures may significantly change their architecture in response to diverse stimuli. When excessive deformation is applied, they may eventually become unstable. Traditionally, mechanical instabilities have been viewed as an inconvenience, with research focusing on how to avoid them. Here, I will demonstrate that these instabilities can be exploited to design materials with novel, switchable functionalities. The abrupt changes introduced into the architecture of soft materials by instabilities will be used to change their shape in a sudden, but controlled manner. Possible and exciting applications include materials with unusual properties such negative Poisson's ratio, phononic crystals with tunable low-frequency acoustic band gaps and reversible encapsulation systems.
Scientific Electronic Library Online (English)
G. R. X., Souza; S. B., Gabriel; A. F., Ribeiro; L. H. de, Almeida.
Full Text Available A superliga de níquel X-750 pertence a classe das ligas níquel-cromo-alumínio-titânio e é indicada para aplicações em altas temperaturas e ambientes corrosivos. Entre outras aplicações é utilizada para a fabricação de molas helicoidais operando como componente estrutural de reatores nucleares. A pre [...] sença do titânio em teores da ordem de 2,5% em peso confere à liga elevada resistência mecânica pelo mecanismo de endurecimento por precipitação da fase coerente ?'. Por outro lado o controle das propriedades mecânicas finais é fortemente dependente do grau de encruamento prévio ao tratamento térmico de envelhecimento. Segundo a norma AMS 5698G, o fio da superliga X-750 a ser utilizado na fabricação de molas helicoidais deve ser submetido a um tratamento térmico de solubilização e em seguida deve ser reduzido a frio de aproximadamente 15% de sua área. Após a redução, a mola é conformada e submetida a um tratamento de precipitação e resfriada ao ar. No entanto, não se encontra na literatura cientifica dados suficientes para caracterizar as propriedades mecânicas, particularmente os níveis de resistência, em função dos mecanismos de endurecimento atuantes. O presente trabalho teve como objetivo estudar diferentes rotas de processamento para se obter fios da liga X-750 de forma a maximizar as propriedades para a aplicação na fabricação de molas helicoidais em função do grau de deformação do último passe de trefilação. As diferentes etapas de processamento foram caracterizadas por microscopia ótica e eletrônica de varredura e as propriedades mecânicas por ensaio de dureza Vickers e tração uniaxial. Observou-se, como esperado, que o ganho de resistência devido à deformação foi proporcional ao grau de deformação aplicado. Por outro lado, entretanto, o ganho de resistência devido ao tratamento térmico de envelhecimento é reduzida com o aumento do grau de deformação, ocasionando em uma tensão limite de escoamento cada vez mais dependente do grau de encruamento e, dessa forma, em prejuízo de tenacidade. Abstract in english The nickel base superalloy X-750 is a nickel-chromium-titanium-aluminum alloy that is suitable for high temperature applications and corrosive environments. Among others applications, it can be used in helical springs manufacturing acting as a structural component in nuclear reactors. The titanium p [...] resence at levels of about 2.5wt% gives the alloy high strength by precipitation of the coherent phase ?'. According to the standard AMS 5698G, the wire of X-750 alloy to be used in helical springs manufacturing must be subjected to a solution heat treatment and then be cold reduced by approximately 15% of its area. After the reduction, the spring is shaped as well as precipitation heat treated and air cooling. However, there is not enough data in the scientific literature to characterize the mechanical properties, particularly resistance levels as a function of these hardening mechanisms. This paper aimed to study different processing routes to obtain wires of X-750 alloy in order to maximize the properties for helical springs applications according to the last pass drawing deformation degree. The different processing steps were characterized by optical microscopy and scanning electron microscopy and mechanical properties by Vickers hardness and tensile. As expected, the resistance gain due to deformation was proportional to the deformation degree applied. On the other hand, however, the aging heat treatment contribution is reduced with the deformation degree increasing, resulting in a yield stress increasingly dependent on the hardening degree.
Deformable Simplicial Complexes
DEFF Research Database (Denmark)
Misztal, Marek Krzysztof
2010-01-01
In this dissertation we present a novel method for deformable interface tracking in 2D and 3D|deformable simplicial complexes (DSC). Deformable interfaces are used in several applications, such as fluid simulation, image analysis, reconstruction or structural optimization. In the DSC method, the interface (curve in 2D; surface in 3D) is represented explicitly as a piecewise linear curve or surface. However, the domain is also subject to discretization: triangulation in 2D; tetrahedralization in ...
Indian Academy of Sciences (India)
Ramaswamy Jaganathan; Sudeshna Sinha
2005-03-01
Motivated by studies on -deformed physical systems related to quantum group structures, and by the elements of Tsallis statistical mechanics, the concept of -deformed nonlinear maps is introduced. As a specific example, a -deformation procedure is applied to the logistic map. Compared to the canonical logistic map, the resulting family of -logistic maps is shown to have a wider spectrum of interesting behaviours, including the co-existence of attractors – a phenomenon rare in one-dimensional maps.
Diffeomorphic Statistical Deformation Models
DEFF Research Database (Denmark)
Hansen, Michael Sass; Hansen, Mads/Fogtman; Larsen, Rasmus
2007-01-01
In this paper we present a new method for constructing diffeomorphic statistical deformation models in arbitrary dimensional images with a nonlinear generative model and a linear parameter space. Our deformation model is a modified version of the diffeomorphic model introduced by Cootes et al. The modifications ensure that no boundary restriction has to be enforced on the parameter space to prevent folds or tears in the deformation field. For straightforward statistical analysis, principal compo...
Xue, W X; Hagino, K; Li, Z P; Mei, H; Tanimura, Y
2014-01-01
The impurity effect of hyperon on atomic nuclei has received a renewed interest in nuclear physics since the first experimental observation of appreciable reduction of $E2$ transition strength in low-lying states of hypernucleus $^{7}_\\Lambda$Li. Many more data on low-lying states of $\\Lambda$ hypernuclei will be measured soon for $sd$-shell nuclei, providing good opportunities to study the $\\Lambda$ impurity effect on nuclear low-energy excitations. We carry out a quantitative analysis of $\\Lambda$ hyperon impurity effect on the low-lying states of $sd$-shell nuclei at the beyond-mean-field level based on a relativistic point-coupling energy density functional (EDF), considering that the $\\Lambda$ hyperon is injected into the lowest positive-parity ($\\Lambda_s$) and negative-parity ($\\Lambda_p$) states. We adopt a triaxially deformed relativistic mean-field (RMF) approach for hypernuclei and calculate the $\\Lambda$ binding energies of hypernuclei as well as the potential energy surfaces (PESs) in $(\\beta, \\g...
Deformations of Quantum Field Theories on Curved Spacetimes
Morales, Eric Morfa
2012-01-01
The construction and analysis of deformations of quantum field theories by warped convolutions is extended to a class of globally hyperbolic spacetimes. First, we show that any four-dimensional spacetime which admits two commuting and spacelike Killing vector fields carries a family of wedge regions with causal properties analogous to the Minkowski space wedges. Deformations of quantum field theories on these spacetimes are carried out within the operator-algebraic framework - the emerging models share many structural properties with deformations of field theories on flat spacetime. In particular, deformed quantum fields are localized in the wedges of the considered spacetime. As a concrete example, the deformation of the free Dirac field is studied. Second, quantum field theories on de Sitter spacetime with global U(1) gauge symmetry are deformed using the joint action of the internal symmetry group and a one-parameter group of boosts. The resulting theories turn out to be wedge-local and non-isomorphic to t...
Mechanical Behavior of Knitted Fabrics under Bending and Shear Deformation
UÇAR, Mehmet
2003-01-01
It is very important to understand the mechanical response of fabrics under deformation since their aesthetic properties and performance are directly related to their mechanical properties, such as tensile, bending and shear. During use, fabric is always stressed by these kinds of deformations. Fabric properties such as drape, handle, and bagging are also affected by the bending and shear characteristics of the fabric. Thus, this study was carried out to gain a better understanding ...
Deformation mechanisms of experimentally deformed Salina Basin bedded salt
International Nuclear Information System (INIS)
Petrofabrics of deformed salt from the Cleveland area within the Salina Basin are presented. Quasi-static compression at room temperature and 1 MPa confining pressure is dominated by fracture. Incipient failure is evidenced by wide zones of coalesced fractures at an axial strain of 5%. Strain hardening, evidenced by photoelastic effects, abounds under these conditions. At 5 MPa far fewer fractures are found at axial strains of 13%. Photoelastic effects are appreciably diminished at 5 MPa, which must mean more homogeneous ductile flow ensues, perhaps owing to activation of many dislocation mills. Clearly, the brittle-to-ductile transition requires additional petrographic work for documentation. Because the dominant mechanism is very pressure sensitive at relative low mean stresses, it appears necessary to include confining pressure in the deformation mechanism map. Creep at 15 MPa and temperatures >1000C is dominated by thermally activated diffusion. Fracture and photoelastic effects are almost totally suppressed relative to quasi-static experiments at lower confining pressure and temperature. The mechanism of climb into stable polygons is fully documented by etch pit studies in samples that are deformed well into steady state. Creep properties of Cleveland and Avery Island salt are very similar under conditions of elevated temperature and intermediate stresses. As temperature is reduced the predicted flow stress of Cleveland becomes greater than that of Avery Island. However, extrapolation of either flow law to low temperature is not justified because the governing mechanisms change from climb to fracture and glide
Strengthening of HSLA steels by cool deformation
International Nuclear Information System (INIS)
In microalloyed steels, the refinement of ferrite grains together with a controlled amount of precipitation has key roles in the mechanical properties improvement. Applying small amounts of deformation, at very low hot working temperatures (i.e. coiling temperature), in the ferrite region (i.e. cool deformation) has an appreciable strengthening effect via controlling the final microstructure of the steel. One of the microstructural effects is thought to be the much finer and more uniformly dispersed precipitates in the steel matrix. In the present study, the effects of Nb and Cu on mechanical properties and corresponding microstructures in steels with different levels of cool deformation are investigated. The mechanical properties of the samples were determined using the shear punch test and the microstructure was examined by scanning and transmission electron microscopy. Thermodynamic simulations with FactSage were done to further analyze the precipitation possibility of different elements. It has been found that these alloying elements respond very well to cool deformation, with the strength being highest in steels containing both Nb and Cu. However, a cool deformation effect in the non-Nb and Cu bearing steel is also observed. In all cases, it was confirmed that precipitation plays a key role in the effect of cool deformation, with much of the precipitation taking place dynamically. Nevertheless, static processes also seem to have a measurable effect on room temperature properties. Even low amounts of copper (e.g. ?0.4 wt%) can contribute to strengthening of the steel. The Cu addition is found to affect the mechanical properties by affecting the precipitation and growth of Nb compounds.
International Nuclear Information System (INIS)
Copper-based high strength and high electrical conductivity nano-composite wires reinforced by Nb nano-tubes are prepared by severe plastic deformation, applied with an Accumulative Drawing and Bundling process (ADB), for the windings of high pulsed magnets. The ADB process leads to a multi-scale Cu matrix containing up to N = 854 (52.2.106) continuous parallel Nb tubes with diameter down to few tens nano-meters. After heavy strain, the Nb nano-tubes exhibit a homogeneous microstructure with grain size below 100 nm. The Cu matrix presents a multi-scale microstructure with multi-modal grain size distribution from the micrometer to the nano-meter range. The use of complementary characterization techniques at the microscopic and macroscopic level (in-situ tensile tests in the TEM, nano-indentation, in-situ tensile tests under high energy synchrotron beam) shed light on the interest of the multi-scale nature of the microstructure to achieve extreme mechanical properties, therefore allowing for design guidelines to further improve these properties. (authors)
International Nuclear Information System (INIS)
A compression test simulating heavy-reduction single-pass rolling was conducted to investigate the microstructural evolution based on the formation of a bimodal structure and the mechanical properties of 0.01% and 0.1% carbon steels and niobium steel. When thermomechanical processing was conducted near and above the critical transformation temperature (Ac3), microstructures of all steels were significantly refined and consisted of equiaxed grains without elongated grains. Nevertheless, these microstructures showed weak or no formation of the bimodal structure or coarse grains with decreasing carbon content, while they showed bimodal structure formation when 0.2% carbon steel was used in our previous research. The average grain size of Nb steel was about 2 ?m and its microstructure was uniformly refined. These may be attributed to a decrease in the number of nucleation sites with decreasing carbon content in low-carbon steels and the occurrence of nucleation at grain boundaries as well as in grain interiors in Nb steel during processing. Mechanical properties of all steels deformed above the critical transformation temperature exhibited high performance characteristics with superior strength and marked elongation. Their fractographs indicated ductile fracture, which was revealed by SEM observation after a tensile test
Resurgent deformation quantisation
International Nuclear Information System (INIS)
We construct a version of the complex Heisenberg algebra based on the idea of endless analytic continuation. The algebra would be large enough to capture quantum effects that escape ordinary formal deformation quantisation. -- Highlights: •We construct resurgent deformation quantisation. •We give integral formulæ. •We compute examples which show that hypergeometric functions appear naturally in quantum computations
Resurgent deformation quantisation
Energy Technology Data Exchange (ETDEWEB)
Garay, Mauricio, E-mail: garay91@gmail.com [Institut für Mathematik, FB 08 Physik, Mathematik und Informatik, Johannes Gutenberg-Universität, 55099 Mainz (Germany); Goursac, Axel de, E-mail: Axelmg@melix.net [Chargé de Recherche au F.R.S.-FNRS, IRMP, Université Catholique de Louvain, Chemin du Cyclotron, 2, B-1348 Louvain-la-Neuve (Belgium); Straten, Duco van, E-mail: straten@mathematik.uni-mainz.de [Institut für Mathematik, FB 08 Physik, Mathematik und Informatik, Johannes Gutenberg-Universität, 55099 Mainz (Germany)
2014-03-15
We construct a version of the complex Heisenberg algebra based on the idea of endless analytic continuation. The algebra would be large enough to capture quantum effects that escape ordinary formal deformation quantisation. -- Highlights: •We construct resurgent deformation quantisation. •We give integral formulæ. •We compute examples which show that hypergeometric functions appear naturally in quantum computations.
Kim, EunJung; Guilak, Farshid; Haider, Mansoor A.
2010-01-01
The pericellular matrix (PCM) is the narrow tissue region surrounding all chondrocytes in articular cartilage and, together, the chondrocyte(s) and surrounding PCM have been termed the chondron. Previous theoretical and experimental studies suggest that the structure and properties of the PCM significantly influence the biomechanical environment at the microscopic scale of the chondrocytes within cartilage. In the present study, an axisymmetric boundary element method (BEM) was developed for ...
Energy Technology Data Exchange (ETDEWEB)
Vasco, D.W.
2011-10-01
Using an asymptotic technique, valid when the medium properties are smoothly-varying, I derive a semi-analytic expression for the propagation velocity of a quasi-static disturbance traveling within a nonlinear-elastic porous medium. The phase, a function related to the propagation time, depends upon the properties of the medium, including the pressure-sensitivities of the medium parameters, and on pressure and displacement amplitude changes. Thus, the propagation velocity of a disturbance depends upon its amplitude, as might be expected for a nonlinear process. As a check, the expression for the phase function is evaluated for a poroelastic medium, when the material properties do not depend upon the fluid pressure. In that case, the travel time estimates agree with conventional analytic estimates, and with values calculated using a numerical simulator. For a medium with pressure-dependent permeability I find general agreement between the semi-analytic estimates and estimates from a numerical simulation. In this case the pressure amplitude changes are obtained from the numerical simulator.
Fréchet-algebraic deformation quantizations
International Nuclear Information System (INIS)
In this review I present some recent results on the convergence properties of formal star products. Based on a general construction of a Fréchet topology for an algebra with countable vector space basis I discuss several examples from deformation quantization: the Wick star product on the flat phase space m2n gives a first example of a Fréchet algebraic framework for the canonical commutation relations. More interesting, the star product on the Poincare disk can be treated along the same lines, leading to a non-trivial example of a convergent star product on a curved Kahler manifold.
Deformation retracts of Stein spaces
International Nuclear Information System (INIS)
If X is an n-dimensional Stein space, it was proved that X has the homotopy type of a CW-complex of dimension?n and in the algebraic case this was proved with the additional conclusion that the CW-complex is finite. In this paper the authors give an answer to the question if there exists a subset Q of X with the same topological properties as X, for instance Q is a strong deformation retract of X, and Q is a CW-complex of dimension?n. 15 refs
Cosmetic and Functional Nasal Deformities
... nasal complaints. Nasal deformity can be categorized as “cosmetic” or “functional.” Cosmetic deformity of the nose results in a less ... taste , nose bleeds and/or recurrent sinusitis . A cosmetic or functional nasal deformity may occur secondary to ...
q-Deformation of Lorentzian spin foam models
Fairbairn, Winston J
2011-01-01
We construct and analyse a quantum deformation of the Lorentzian EPRL model. The model is based on the representation theory of the quantum Lorentz group with real deformation parameter. We give a definition of the quantum EPRL intertwiner, study its convergence and braiding properties and construct an amplitude for the four-simplexes. We find that the resulting model is finite.
Intermetallic alloys: Deformation, mechanical and fracture behaviour
International Nuclear Information System (INIS)
The state of the art in intermetallic alloys development with particular emphasis on deformation, mechanical and fracture behaviour is documented. This review paper is prepared to lay the ground stones for a future work on mechanical property characterization and fracture behaviour of intermetallic alloys at GKSS. (orig.)
Abdyukhanov, I. M.; Vorobieva, A. E.; Alekseev, M. V.; Mareev, K. A.; Dergunova, E. A.; Peredkova, T. N.; Shikov, A. K.; Utkin, K. V.; Vorobieva, A. V.; Kharkovsky, D. N.
2014-01-01
From 2009 the mass production of the Nb3Sn strands for ITER with the yield of several tens of tons per year operates at JSC Chepetsky Mechanical Plant (Glazov, Russia). In order to enhance the stability of output characteristics of the produced Nb3Sn strands, to increase the Nb filaments dimensional homogeneity the manufacture regimes improvement of the used semiproducts such as Nb rods intended for the superconducting filaments formation in the finished strands has been carried out. In the work the investigations of the Nb rheological behavior, the influence of heat treatment in the wide temperature range from 700 to 1300 °C on the predeformed Nb rods structure and mechanical properties have been performed. Different production routes of the Nb rods, including such operations like forging, extrusion and drawing combined with the recrystallization annealings, were used. Composite Nb3Sn strands have been produced and their electrophysical properties have been tested. For the first time influence of the niobium rods manufacture regimes on the current carrying capacity of the industrial Nb3Sn strands has been investigated.
Electroplastic deformation of tungsten
International Nuclear Information System (INIS)
Electroplastic deformation of tungsten during elongation of wire 0.3 mm in diameter in flowing argon with simultaneous passing of electric current and sample heating from 300 to 700 deg C is investigated. Elongation diagrams are obtained, from which it follows that under the effect of current pulses the release of deforming effort takes place, its value depending on the time of pulse effect and voltage amplitude. It is ascertained that ductility of wire, deformed with current imposition by 40-45 % exceeds the values obtained without current. Simultaneously transverse structure refinement in the wire takes place. Texture parameters of tungsten wire after electroplastic treatment are determined
Deformation quantization: a survey
Energy Technology Data Exchange (ETDEWEB)
Bordemann, M [Laboratoire des Mathematiques et Applications, Universite de Haute Alsace, Mulhouse, 4, rue des Freres Lumiere, 68093 Mulhouse (France)], E-mail: Martin.Bordemann@uha.fr
2008-02-01
We give an introduction to deformation quantization with emphasis on explicit formulas and sketch some partial results on theory of morphisms and modules in that framework and their relation to Poisson geometry.
Universal deformation formulas.
Czech Academy of Sciences Publication Activity Database
Remm, E.; Markl, Martin
2015-01-01
Ro?. 43, ?. 11 (2015), s. 4711-4734. ISSN 0092-7872 Institutional support: RVO:67985840 Keywords : algebra * deformation * twisting Impact factor: 0.388, year: 2014 http://www.tandfonline.com/doi/abs/10.1080/00927872.2014.949729
Extremely deformable structures
2015-01-01
Recently, a new research stimulus has derived from the observation that soft structures, such as biological systems, but also rubber and gel, may work in a post critical regime, where elastic elements are subject to extreme deformations, though still exhibiting excellent mechanical performances. This is the realm of ‘extreme mechanics’, to which this book is addressed. The possibility of exploiting highly deformable structures opens new and unexpected technological possibilities. In particular, the challenge is the design of deformable and bi-stable mechanisms which can reach superior mechanical performances and can have a strong impact on several high-tech applications, including stretchable electronics, nanotube serpentines, deployable structures for aerospace engineering, cable deployment in the ocean, but also sensors and flexible actuators and vibration absorbers. Readers are introduced to a variety of interrelated topics involving the mechanics of extremely deformable structures, with emphasis on ...
Deformations of quantum field theories on curved spacetimes
International Nuclear Information System (INIS)
The construction and analysis of deformations of quantum field theories by warped convolutions is extended to a class of globally hyperbolic spacetimes. First, we show that any four-dimensional spacetime which admits two commuting and spacelike Killing vector fields carries a family of wedge regions with causal properties analogous to the Minkowski space wedges. Deformations of quantum field theories on these spacetimes are carried out within the operator-algebraic framework - the emerging models share many structural properties with deformations of field theories on flat spacetime. In particular, deformed quantum fields are localized in the wedges of the considered spacetime. As a concrete example, the deformation of the free Dirac field is studied. Second, quantum field theories on de Sitter spacetime with global U(1) gauge symmetry are deformed using the joint action of the internal symmetry group and a one-parameter group of boosts. The resulting theories turn out to be wedge-local and non-isomorphic to the initial one for a class of theories, including the free charged Dirac field. The properties of deformed models coming from inclusions of CAR-algebras are studied in detail. Third, the deformation of the scalar free field in the Araki-Wood representation on Minkowski spacetime is discussed as a motivating example. (author)
Kreuzer, Martin; Robbiano, Lorenzo
2007-01-01
Here we study the problem of generalizing one of the main tools of Groebner basis theory, namely the flat deformation to the leading term ideal, to the border basis setting. After showing that the straightforward approach based on the deformation to the degree form ideal works only under additional hypotheses, we introduce border basis schemes and universal border basis families. With their help the problem can be rephrased as the search for a certain rational curve on a bor...
Deformation through Transformations
Roytburd, A.
1996-01-01
Constitutive stress-strain relations for transformational deformation are discussed. A crystal which can be in two possible phase states is considered. A phase transformation begins during the deformation after a certain amount of elastic strain. For each fixed level of strain an equilibrium polydomain microstructure is established which corresponds to a minimum in the free energy of the crystal. The equilibrium microstructure consists of plane-parallel layers of a product phase separated by ...
Kinematics of deformable media
DasGupta, Anirvan; Nandan, Hemwati; Kar, Sayan
2007-01-01
We investigate the kinematics of deformations in two and three dimensional media by explicitly solving (analytically) the evolution equations (Raychaudhuri equations) for the expansion, shear and rotation associated with the deformations. The analytical solutions allow us to study the dependence of the kinematical quantities on initial conditions. In particular, we are able to identify regions of the space of initial conditions that lead to a singularity in finite time. Some...
Stevens, Jan
2003-01-01
These notes deal with deformation theory of complex analytic singularities and related objects. The first part treats general theory. The central notion is that of versal deformation in several variants. The theory is developed both in an abstract way and in a concrete way suitable for computations. The second part deals with more specific problems, specially on curves and surfaces. Smoothings of singularities are the main concern. Examples are spread throughout the text.
Quantum mechanics as a deformation of classical mechanics
International Nuclear Information System (INIS)
Mathematical properties of deformations of the Poisson Lie algebra and of the associative algebra of functions on a symplectic manifold are given. The suggestion to develop quantum mechanics in terms of these deformations is confronted with the mathematical structure of the latter. As examples, spectral properties of the harmonic oscillator and of the hydrogen atom are derived within the new formulation. Further mathematical generalization and physical applications are proposed. (Auth.)
Particle-Dependent Deformations of Lorentz Symmetry
Directory of Open Access Journals (Sweden)
Giovanni Amelino-Camelia
2012-07-01
Full Text Available I report results suggesting that it is possible to introduce laws of relativistic kinematics endowing different types of particles with suitably different deformed-Lorentz-symmetry properties. I also consider some possible applications of these results, among which I highlight those relevant for addressing a long-standing challenge in the description of composite particles, such as atoms, within quantum-gravity-inspired scenarios with Planck-scale deformations of Lorentz symmetry. Some of the new elements here introduced in the formulation of relativistic kinematics appear to also provide the starting point for the development of a correspondingly novel mathematical formulation of spacetime-symmetry algebras.
Energy Technology Data Exchange (ETDEWEB)
Trabert, E; Beiersdorfer, P; Brown, G V; Boyce, K; Kelley, R L; Kilbourne, C A; Porter, F S; Szymkowiak, A
2005-11-11
A microcalorimeter with event mode capability for time-resolved soft-x-ray spectroscopy, and a high-resolution flat-field EUV spectrometer have been employed at the Livermore EBIT-I electron beam ion trap for observations and wavelength measurements of M1, E2, and M3 decays of long-lived levels in the Ni-like ions Xe{sup 26+}, Cs{sup 27+}, and Ba{sup 28+}. Of particular interest is the lowest excited level, 3d{sup 9}4s {sup 3}D{sub 3}, which can only decay via a magnetic octupole (M3) transition. For this level in Xe an excitation energy of (590.40 {+-} 0.03eV) and a level lifetime of (11.5 {+-} 0.5 ms) have been determined.
Directory of Open Access Journals (Sweden)
Trémolières P.
2006-11-01
Full Text Available Cet article présente les principaux résultats d'une étude menée en commun par l'Institut Français du Pétrole (IFP et la Société Nationale Elf Aquitaine (Production (SNEA (P, étude qui avait pour but de rechercher l'influence des contraintes tectoniques sur les propriétés pétrophysiques matricielles des réservoirs calcaires. Ces travaux, ayant porté principalement surle Burdigalien des Alpilles (Provence et accessoirement sur le Turonien de Mareuil (Aquitaine et la « Scaglia bianca » du Monte Conero (Ancàne-Itatie, ont permis de mettre en évidence - des variations importantes de la porosité et de la perméabilité en fonction de la position structurale du matériau et, à plus petite échelle, de la courbure des couches; - un double processus de la réduction des porosité et perméabilité : soit par tassement mécanique, soit par cristallisation dans les pores d'une calcite provenant probablement d'une dissolution le long de joints stylolithiques d'origine tectonique. On montre enfin qu'en certaines zones particulières (dans les périclinaux ou à l'aplomb d'accidents profonds jouant en faille inverse les effets des contraintes tectoniques sur les qualités matricielles peuvent être très importants et survenir avant la structuration des couches par plissement. This article describes the main results of a joint Institut Français du Pétrole (IFP-Société Nationale Elf Aquitaine (Production (SNEA (P research project on the influence of tectonic stresses on thé petrophysical matrix properties of limestone reservoirs. Research mainly concentrated on the Burdigalien from the Alpilles mountains in ihe Provence région and accessorily on the Turonian from Mareuil in the Aquitaine region and Scaglia Bianca from Monte Conero in Anconia, Italy. The following findings were made: - considerable variations in porosity and permeability can be found, depending on the structural position of the material and, on a smaller scale, on the curve of the loyers; - there is a double porosity and permeability réduction process, either by mechanical settling or by thé crystallization in thé pores of a calcite probably coming from a dissolution occurring along stylolitic joints of tectonic origin. It is also shown that in some specific zones (in periclines or directly underneath deep accidents in thé form of thrust faults thé effects of tectonic stresses on matrix qualities may be very great and may occur prior to the folding structuration of the loyers.
Molybdenum recrystallization deformed by forging and hydropressing
International Nuclear Information System (INIS)
Certain pecularities are studied and recrystallization diagrams of MChVP mark 1 type molybdenum, processed under commercial conditions according to two deformation regimes-forging and hydropressing are constructed. It is shown that in molybdenum subjected both to forging an hydropressing a relatively fine grain is contained under the deformation degrees exceeding 50% and annealings of up to 1600-1700 deg C. Annealing at higher temperatures leads to producing a large-grain structure under all deformation degrees. Hydropressing provides for a more homogeneous structure (as compared to forging) in recrystallized molybdenum, as well as for improvement of strength properties within Tann=800-1500 deg C interval by 20% and elastic properies (Tann=1400-1500 deg C) by 30-50%
Quantum reference frames and deformed symmetries
International Nuclear Information System (INIS)
In the context of constrained quantum mechanics, reference systems are used to construct relational observables that are invariant under the action of the symmetry group. Upon measurement of a relational observable, the reference system undergoes an unavoidable measurement ''back-action'' that modifies its properties. In a quantum-gravitational setting, it has been argued that such a back-action may produce effects that are described at an effective level as a form of deformed (or doubly) special relativity. We examine this possibility using a simple constrained system that has been extensively studied in the context of quantum information. While our conclusions support the idea of a symmetry deformation, they also reveal a host of other effects that may be relevant to the context of quantum gravity, and could potentially conceal the symmetry deformation
Deformation Behavior of Nanoporous Metals
Energy Technology Data Exchange (ETDEWEB)
Biener, J; Hodge, A M; Hamza, A V
2007-11-28
Nanoporous open-cell foams are a rapidly growing class of high-porosity materials (porosity {ge} 70%). The research in this field is driven by the desire to create functional materials with unique physical, chemical and mechanical properties where the material properties emerge from both morphology and the material itself. An example is the development of nanoporous metallic materials for photonic and plasmonic applications which has recently attracted much interest. The general strategy is to take advantage of various size effects to introduce novel properties. These size effects arise from confinement of the material by pores and ligaments, and can range from electromagnetic resonances to length scale effects in plasticity. In this chapter we will focus on the mechanical properties of low density nanoporous metals and how these properties are affected by length scale effects and bonding characteristics. A thorough understanding of the mechanical behavior will open the door to further improve and fine-tune the mechanical properties of these sometimes very delicate materials, and thus will be crucial for integrating nanoporous metals into products. Cellular solids with pore sizes above 1 micron have been the subject of intense research for many years, and various scaling relations describing the mechanical properties have been developed.[4] In general, it has been found that the most important parameter in controlling their mechanical properties is the relative density, that is, the density of the foam divided by that of solid from which the foam is made. Other factors include the mechanical properties of the solid material and the foam morphology such as ligament shape and connectivity. The characteristic internal length scale of the structure as determined by pores and ligaments, on the other hand, usually has only little effect on the mechanical properties. This changes at the submicron length scale where the surface-to-volume ratio becomes large and the effect of free surfaces can no longer be neglected. As the material becomes more and more constraint by the presence of free surfaces, length scale effects on plasticity become more and more important and bulk properties can no longer be used to describe the material properties. Even the elastic properties may be affected as the reduced coordination of surface atoms and the concomitant redistribution of electrons may soften or stiffen the material. If, and to what extend, such length scale effects control the mechanical behavior of nanoporous materials depends strongly on the material and the characteristic length scale associated with its plastic deformation. For example, ductile materials such as metals which deform via dislocation-mediated processes can be expected to exhibit pronounced length scale effects in the sub-micron regime where free surfaces start to constrain efficient dislocation multiplication. In this chapter we will limit our discussion to our own area of expertise which is the mechanical behavior of nanoporous open-cell gold foams as a typical example of nanoporous metal foams. Throughout this chapter we will review our current understanding of the mechanical properties of nanoporous open-cell foams including both experimental and theoretical studies.
About deformation and rigidity in relativity
International Nuclear Information System (INIS)
The notion of deformation involves that of rigidity. In relativity, starting from Born's early definition of rigidity, some other ones have been proposed, offering more or less interesting aspects but also accompanied of undesired or even pathological properties. In order to clarify the origin of these difficulties presented by the notion of rigidity in relativity, we analyze with some detail significant aspects of the unambiguous classical, Newtonian, notion. In particular, the relative character of its kinetic definition is pointed out, allowing to predict and to understand the limitations imposed by Herglotz-Noether theorem. Also, its equivalent dynamic definition is obtained and, in contrast, its absolute character is shown. But in spite of this absolute character, the dynamic definition is shown to be not extensible to relativity. The metric deformation of Minkowski space by the presence of a gravitational field is interpreted as a universal deformation, and it is shown that, under natural conditions, only a simple deformation law is possible, relating locally, but in an one-to-one way, gravitational fields and gauge classes of two-forms. We argue that fields of unit vectors associated to the internal gauge class of two-forms of every space-time (and, in particular, of Minkowski space-time) are the relativistic analogues of the classical accelerated observers, i.e. of the classical rigid motions. Some other consequences of the universal law of gravitational deformation are commented
PT-symmetrically deformed shock waves
Cavaglia, Andrea
2012-01-01
We investigate for a large class of nonlinear wave equations, which allow for shock wave formations, how these solutions behave when they are PT-symmetrically deformed. For real solutions we find that they are transformed into peaked solutions with a discontinuity in the first derivative instead. The systems we investigate include the PT-symmetrically deformed inviscid Burgers equation recently studied by Bender and Feinberg, for which we show that it does not develop any shocks, but peaks instead. In this case we exploit the rare fact that the PT-deformation can be provided by an explicit map found by Curtright and Fairlie together with the property that the undeformed equation can be solved by the method of characteristics. We generalise the map and observe this type of behaviour for all integer values of the deformation parameter epsilon. The peaks are formed as a result of mapping the multi-valued self-avoiding shock profile to a multi-valued self-crossing function by means of the PT-deformation. For some...
Deformation and fracture of emulsion-filled gels: Effect of oil content and deformation speed
Sala, G.; Vliet, T.; Cohen Stuart, M.A.; Aken, G.A., van; van de Velde, F.
2009-01-01
The large deformation properties of gelatine, ¿-carrageenan and whey protein isolate (WPI) gels filled with bound and unbound oil droplets were studied as a function of compression speed. The rheological properties of the gel matrices controlled the compression speed-dependency of the gels containing oil droplets. Polymer gels (gelatine and ¿-carrageenan gels) showed a predominantly elastic behaviour. Their Young's modulus was not affected by the compression speed. The increase of fracture st...
Deformation Theory ( Lecture Notes ).
Czech Academy of Sciences Publication Activity Database
Doubek, M.; Markl, Martin; Zima, P.
2007-01-01
Ro?. 43, ?. 5 (2007), s. 333-371. ISSN 0044-8753. [Winter School Geometry and Physics/27./. Srní, 13.01.2007-20.01.2007] R&D Projects: GA ?R GA201/05/2117 Institutional research plan: CEZ:AV0Z10190503 Keywords : deformation * Mauerer-Cartan equation * strongly homotopy Lie algebra Subject RIV: BA - General Mathematics
Deformable Simplicial Complexes
DEFF Research Database (Denmark)
Misztal, Marek Krzysztof
2010-01-01
In this dissertation we present a novel method for deformable interface tracking in 2D and 3D|deformable simplicial complexes (DSC). Deformable interfaces are used in several applications, such as fluid simulation, image analysis, reconstruction or structural optimization. In the DSC method, the interface (curve in 2D; surface in 3D) is represented explicitly as a piecewise linear curve or surface. However, the domain is also subject to discretization: triangulation in 2D; tetrahedralization in 3D. This way, the interface can be alternatively represented as a set of edges/triangles separating triangles/tetrahedra marked as outside from those marked as inside. Such an approach allows for robust topological adaptivity. Among other advantages of the deformable simplicial complexes there are: space adaptivity, ability to handle and preserve sharp features, possibility for topology control. We demonstrate those strengths in several applications. In particular, a novel, DSC-based fluid dynamics solver has been developed during the PhD project. A special feature of this solver is that due to the fact that DSC maintains an explicit interface representation, surface tension is more easily dealt with. One particular advantage of DSC is the fact that as an alternative to topology adaptivity, topology control is also possible. This is exploited in the construction of cut loci on tori where a front expands from a single point on a torus and stops when it self-intersects.
Transfer involving deformed nuclei
International Nuclear Information System (INIS)
Results are reviewed of 1- and 2-neutron transfer reactions at near-barrier energies for deformed nuclei. Rotational angular momentum and excitation patterns are examined. A strong tendency to populating high spin states within a few MeV of the yrast line is noted, and it is interpreted as preferential transfer to rotation-aligned states. 16 refs., 12 figs
Optically Driven Deformable Mirrors
Hemmati, Hamid
2006-01-01
Optically driven deformable mirrors may eventually supplant electrically driven deformable mirrors in some adaptive-optics and active-optics applications. Traditionally, the mirror facets in electrically driven deformable mirrors are actuated, variously, by means of piezoelectric, electrostrictive, microelectromechanical, liquid-crystal, or thermal devices. At least one such device must be dedicated to each facet, and there must be at least one wire carrying a control or drive signal to the device. If a deformable mirror comprises many (e.g., thousands) of facets, then wiring becomes a major problem for design, and the problem is compounded in cases of piezoelectric or other actuators for which high drive voltages are required. In contrast, in optically driven mirrors, the wiring problem is eliminated. The basic principle of actuation of an optically driven deformable mirror is to use a laser beam to actuate a material. For example, a laser beam can be used to heat a material to make the material thermally expand to displace a mirror facet. In an experiment to demonstrate this principle, the actuator was a Golay cell having a diameter of approximately equal to 6 mm and a length of approximately equal to 10 mm. The beam from a laser diode was aimed at an absorber in the cell, thereby heating the gas in the cell. A mirror mounted on a 12.5-micron-thick polyethylene terephthalate diaphragm at one end of the cell became displaced as the gas expanded against the diaphragm. In one representative pair of experiments at a laser beam power of 0.23 W, the beam was mechanically chopped at frequencies of 1 and 5 Hz. The mirror exhibited corresponding oscillating displacements having amplitudes of 373 and 83 micron, respectively
Deformed "Commutative" Chern - Simons System
Zhang, Jian-zu
2009-01-01
Noncommutative Chern - Simons' system is non-perturbatively investigated at a full deformed level. A deformed "commutative" phase space is found by a non-canonical change between two sets of deformed variables of noncommutative space. It is explored that in the "commutative" phase space all calculations are similar to the case in commutative space. Spectra of the energy and angular momentum of the Chern - Simons' system are obtained at the full deformed level. The noncommuta...
Symmetric $q$-deformed KP hierarch
Tian, Kelei; He, Jingsong; Su, Yucai
2014-01-01
Based on the analytic property of the symmetric $q$-exponent $e_q(x)$, a new symmetric $q$-deformed Kadomtsev-Petviashvili ($q$-KP) hierarchy associated with the symmetric $q$-derivative operator $\\partial_q$ is constructed. Furthermore, the symmetric $q$-CKP hierarchy and symmetric $q$-BKP hierarchy are defined. Here we also investigate the additional symmetries of the symmetric $q$-KP hierarchy.
Deformation quantization of bosonic strings
International Nuclear Information System (INIS)
Deformation quantization of bosonic strings is considered. We show that the light-cone gauge is the most convenient classical description to perform the quantization of bosonic strings in the deformation quantization formalism. Similar to the field theory case, the oscillator variables greatly facilitates the analysis. The mass spectrum, propagators and the Virasoro algebra are finally described within this deformation quantization scheme. (author)
International Nuclear Information System (INIS)
The q-deformed kink of the ??4 -model is obtained via the normalisable ground state eigenfunction of a fluctuation operator associated with the q-deformed hyperbolic functions. The kink mass, the bosonic zero-mode and the q-deformed potential in 1+1 dimensions are found. (author)
Thermostatistics of the multi-dimensional q-deformed fermionic Newton oscillators
International Nuclear Information System (INIS)
The algebraic and representative properties of the multi-dimensional q-deformed fermionic Newton oscillator algebra are discussed. This algebra is covariant under the undeformed group U(n). The high- and low-temperature thermostatistical properties of a gas of the multi-dimensional q-deformed fermionic Newton oscillators are obtained
Quantum deformation of two four-dimensional spin foam models
Fairbairn, Winston J; Meusburger, Catherine(Department Mathematik, FAU Erlangen-Nürnberg, Cauerstr. 11, D-91058 Erlangen, Germany)
2010-01-01
We construct the q-deformed version of two four-dimensional spin foam models, the Euclidean and Lorentzian versions of the EPRL model. The q-deformed models are based on the representation theory of two copies of U_q(su(2)) at a root of unity and on the quantum Lorentz group with a real deformation parameter. For both models we give a definition of the quantum EPRL intertwiners, study their convergence and braiding properties and construct an amplitude for the four-simplexes...
Deformation inequivalent complex conjugated complex structures and applications
Kharlamov, V M; Kulikov, Vik.
2001-01-01
Here, we resume and broaden the results concerned which appeared in math.AG/0101098 and math.AG/0104021. We start from summing up our example of a complex algebraic surface which is not deformation equivalent to its complex conjugate and which, moreover, has no homeomorphisms reversing the canonical class. Then, we construct several series of higher dimensional compact complex manifolds having the same property. We end with discussing applications to the Dif=Def problems, to the existence of diffeomorphic plane cuspidal curves non equivalent under equisingular deformations and to the existence of (deformation) non equivalent symplectic structures with opposite canonical classes.
Characteristics of aluminum alloy microplastic deformation in different structural states
Energy Technology Data Exchange (ETDEWEB)
Seregin, G.V.; Efimenko, L.L.; Leonov, M.V. [Novosibirsk Pedagogical Inst. (Russian Federation)
1995-07-01
The solution to the problem of improving the mechanical properties (including cyclic strength) of structural materials is largely dependent on our knowledge of the laws governing the development of microplastic deformations in them. The effect of heat and mechanical treatment on the elastoplastic properties and fatigue resistance of the commercial aluminum alloys AK4-1 and D16 is analyzed.
Austenite-martensite transformation in ADI by plastic deformation
International Nuclear Information System (INIS)
In this article, retained austenite-martensite transformation occurred after plastic deformation and parameters that affect martensitic transformation in ADI is observed. Beside the technical and commercial advantages of ADI, martensitic transformation provides lower production costs and superior mechanical properties such as hardness and wearing resistance. In order to study this phenomenon, austempered GGG60 specimens are subjected to a fatigue test that causes plastic deformation. Afterward the specimens are investigated with metallography, mechanical testing and x-ray diffraction techniques. (Original)
Cell Migration Driven by Cooperative Substrate Deformation Patterns
Angelini, Thomas E.; Hannezo, Edouard; Trepat, Xavier; Fredberg, Jeffrey J.; Weitz, David A
2010-01-01
Most eukaryotic cells sense and respond to the mechanical properties of their surroundings. This can strongly influence their collective behavior in embryonic development, tissue function, and wound healing. We use a deformable substrate to measure collective behavior in cell motion due to substrate mediated cell-cell interactions. We quantify spatial and temporal correlations in migration velocity and substrate deformation, and show that cooperative cell-driven patterns of substrate deformat...
Modeling the behavior of inclusions in plastic deformation of steels
Luo, Chunhui
2001-01-01
This doctoral thesis presents a modeling method fordemonstrating the behavior of inclusions and their surroundingmatrix during plastic deformation of steels. Inclusions are inescapable components of all steels. Moreknowledge about their behavior in processes such as rolling andforging is necessary for carrying out the forming processes ina more proper way so that the properties of the final productare improved. This work is focussed on deformation ofinclusions together with void formation at ...
An investigation into the water retention behaviour of deformable soils
Salager, Simon; Nuth, Mathieu; Ferrari, Alessio; Laloui, Lyesse
2013-01-01
The paper presents an experimental and modelling approach for the soil water retention behaviour of two deformable soils. The objective is to investigate the physical mechanisms that govern the soil water retention properties and to propose a constitutive framework for the soil water retention curve accounting for the initial state of compaction and deformability of soils. A granular soil and a clayey soil were subjected to drying over a wide range of suctions so that the residual state of sa...
Deformed hyperbolic black holes
Chen, Yu; Lim, Yen-Kheng; Teo, Edward
2015-08-01
Black holes with planar or hyperbolic horizons are known to exist in anti-de Sitter (AdS) space, alongside the usual ones with spherical horizons. In this paper, we consider a one-parameter generalization of these black holes that is contained in the AdS C-metric. In terms of the domain-structure analysis recently developed for such solutions, these black holes have a domain in the shape of a triangle. It is shown that the horizons of these black holes are deformed hyperbolic spaces, with the new parameter controlling the amount of deformation. The space-times are static and completely regular outside the horizons. We argue that these black holes are hyperbolic analogues of the "slowly accelerating" spherical black holes known to exist in AdS space.
Deformed hyperbolic black holes
Chen, Yu; Teo, Edward
2015-01-01
Black holes with planar or hyperbolic horizon topology are known to exist in AdS space, alongside the usual ones with spherical topology. In this paper, we consider a one-parameter generalisation of these black holes that is contained in the AdS C-metric. In terms of the domain-structure analysis recently developed for such solutions, these black holes have a domain in the shape of a triangle. It is shown that the horizons of these black holes are deformed hyperbolic spaces, with the new parameter controlling the amount of deformation. The space-times are static and completely regular outside the horizons. We argue that these black holes are hyperbolic analogues of the "slowly accelerating" spherical black holes known to exist in AdS space.
Marginally Deformed Starobinsky Gravity
DEFF Research Database (Denmark)
Codello, A.; Joergensen, J.; Sannino, Francesco; Svendsen, O.
2015-01-01
We show that quantum-induced marginal deformations of the Starobinsky gravitational action of the form $R^{2(1 -\\alpha)}$, with $R$ the Ricci scalar and $\\alpha$ a positive parameter, smaller than one half, can account for the recent experimental observations by BICEP2 of primordial tensor modes. We also suggest natural microscopic (non) gravitational sources of these corrections and demonstrate that they lead generally to a nonzero and positive $\\alpha$. Furthermore we argue, that within this f...
Joining by plastic deformation
DEFF Research Database (Denmark)
Mori, Ken-ichiro; Bay, Niels; Fratini, Livan; Micari, Fabrizio; Tekkaya, A. Erman
2013-01-01
As the scale and complexity of products such as aircraft and cars increase, demand for new functional processes to join mechanical parts grows. The use of plastic deformation for joining parts potentially offers improved accuracy, reliability and environmental safety as well as creating opportunities to design new products through joining dissimilar materials. This paper aims to provide an overview of the state of the art in such joining processes, including cold welding, friction stir welding, ...
Cold deformation of ADI castings: Martensitic transformation
International Nuclear Information System (INIS)
Research and applications in austempered ductile iron (ADI castings) have recently undergone noticeable progress in the industrialized world, becoming a highly competitive engineering material. The notable properties of these castings derive from their austenitic matrix stabilized by carbon, a thermally stable austenite during the austenizing process but possibly turning into martensite when undergoing plastic deformation. This work aims to study the changing structure of an ADI casting caused by one directional cold lamination. The samples that were studied were obtained from two nodular castings, one without alloying and the other alloyed with Cu, Ni and Mo. The samples were austenized in the first stage of the austempering process at 910oC for 80 min. Then in the second stage the unalloyed samples were austempered at 410oC for 10 min and the alloyed samples for 120 min. After the thermal treatment, the test pieces were deformed 0% to 25% by cold lamination. The quantification of the phases was performed using x-ray diffraction and the metallographic study using optic and Scanning Electronic Microscopy. The results show that the martensitic phase obtained by deformation is a very fine structure that evolves into a thicker one when the deformation of the samples increases (CW)
Lu, Bing-Nan; Zhao, En-Guang; Zhou, Shan-Gui
2013-01-01
We have developed multi-dimensional constrained covariant density functional theories (MDC-CDFT) for finite nuclei in which the shape degrees of freedom \\beta_{\\lambda\\mu} with even \\mu, e.g., \\beta_{20}, \\beta_{22}, \\beta_{30}, \\beta_{32}, \\beta_{40}, etc., can be described simultaneously. The functional can be one of the following four forms: the meson exchange or point-coupling nucleon interactions combined with the non-linear or density-dependent couplings. For the pp channel, either the BCS approach or the Bogoliubov transformation is implemented. The MDC-CDFTs with the BCS approach for the pairing (in the following labelled as MDC-RMF models with RMF standing for "relativistic mean field") have been applied to investigate multi-dimensional potential energy surfaces and the non-axial octupole $Y_{32}$-correlations in N=150 isotones. In this contribution we present briefly the formalism of MDC-RMF models and some results from these models. The potential energy surfaces with and without triaxial deformatio...
Application of deformation-mechanism maps to the study of in-reactor behavior of carbide fuels
International Nuclear Information System (INIS)
Deformation-mechanism maps have been constructed to describe in- and out-of-reactor deformation behavior of carbide nuclear fuels. Maps were generated from basic physical-property data using the approach of Ashby. Applications of the maps to description of the in-reactor deformation behaviour of carbide fuels are discussed. (Auth.)
A generalized anisotropic deformation formulation for geomaterials
Lei, Z.; Rougier, Esteban; Knight, E. E.; Munjiza, A.; Viswanathan, H.
2015-10-01
In this paper, the combined finite-discrete element method (FDEM) has been applied to analyze the deformation of anisotropic geomaterials. In the most general case geomaterials are both non-homogeneous and non-isotropic. With the aim of addressing anisotropic material problems, improved 2D FDEM formulations have been developed. These formulations feature the unified hypo-hyper elastic approach combined with a multiplicative decomposition-based selective integration for volumetric and shear deformation modes. This approach is significantly different from the co-rotational formulations typically encountered in finite element codes. Unlike the co-rotational formulation, the multiplicative decomposition-based formulation naturally decomposes deformation into translation, rotation, plastic stretches, elastic stretches, volumetric stretches, shear stretches, etc. This approach can be implemented for a whole family of finite elements from solids to shells and membranes. This novel 2D FDEM based material formulation was designed in such a way that the anisotropic properties of the solid can be specified in a cell by cell basis, therefore enabling the user to seed these anisotropic properties following any type of spatial variation, for example, following a curvilinear path. In addition, due to the selective integration, there are no problems with volumetric or shear locking with any type of finite element employed.
Anomalously Large Deformation in Some Medium and Heavy Nuclei
International Nuclear Information System (INIS)
We investigate the properties of the Ce isotopes with neutron number N = 60-90 and the properties of the heavy nuclei near 242Am within the framework of deformed relativistic mean-field (RMF) theory. A systematic comparison between theoretical results and experimental data is made. The calculated binding energies, two-neutron separation energies, and two-proton separation energies are in good agreement with experimental ones. The variation trend of experimental quadrupole deformation parameters on the Ce isotopes can be approximately reproduced by the RMF model. It is found that there exists an abnormally large deformation in the ground state of proton-rich Ce isotopes. This phenomenon can be the general behavior of proton-rich nuclei on the neighboring isotopic chains such as Nd and Sm isotopes. For the heavy nuclei near 242Am the properties of the ground state and superdeformed isomeric state can be approximately reproduced by the RMF model. The mechanism of the appearance of anomalously large deformation or superdeformation is analyzed and its influence on nuclear properties is discussed. Further experiments to study the anomalously large deformation in some proton-rich nuclei are suggested.
Dynamics, Defects and Deformation in Solid Helium
Beamish, John
2011-03-01
The shear modulus of solid 4 He shows remarkable softening above 100 mK, the same temperature range in which the apparent supersolid disappears in torsional oscillator experiments. We have measured helium's shear modulus and dissipation at frequencies from 0.5 to 8500 Hz. The onset temperature for softening/stiffening is broad, frequency dependent, and is accompanied by a dissipation peak - features typical of a dynamical crossover in a disordered system rather than a true phase transition. This behavior can be qualitatively explained if dislocations are mobile at high temperatures but are pinned by 3 He impurities below 100 mK. To better understand the role of dislocations, we have plastically deformed crystals by rapid thermal quenching and used pressure gradient measurements to study subsequent annealing. In our most recent experiments we have sheared solid helium mechanically and looked at the effect of large deformations on the helium's elastic properties. This work was supported by NSERC.
Layered Structures in Deformed Metals and Alloys
DEFF Research Database (Denmark)
Hansen, Niels; Zhang, Xiaodan
2014-01-01
Layered structures characterize metals and alloys deformed to high strain. The morphology is typical lamellar or fibrous and the interlamellar spacing can span several length scales down to the nanometer dimension. The layered structures can be observed in bulk or in surface regions, which is shown by the way of examples of different processing routes: friction, wire drawing, shot peening, high pressure torsion and rolling. The interlamellar spacing reaches from 5-10 nanometers to about one micrometer and the analysis will cover structural evolution, strengthening parameters and strength-structure relationships. Finally, the results will be discussed based on universal principles for the evolution of microstructure and properties during plastic deformation of metals and alloys from low to high strain.
Marginally Deformed Starobinsky Gravity
DEFF Research Database (Denmark)
Codello, A.; Joergensen, J.
2015-01-01
We show that quantum-induced marginal deformations of the Starobinsky gravitational action of the form $R^{2(1 -\\alpha)}$, with $R$ the Ricci scalar and $\\alpha$ a positive parameter, smaller than one half, can account for the recent experimental observations by BICEP2 of primordial tensor modes. We also suggest natural microscopic (non) gravitational sources of these corrections and demonstrate that they lead generally to a nonzero and positive $\\alpha$. Furthermore we argue, that within this framework, the tensor modes probe theories of grand unification with a large scalar field content.
Quantizing Earth surface deformations
Directory of Open Access Journals (Sweden)
C. O. Bowin
2015-03-01
Full Text Available The global analysis of Bowin (2010 used the global 14 absolute Euler pole set (62 Myr history from Gripp and Gordon (1990 and demonstrated that plate tectonics conserves angular momentum. We herein extend that analysis using the more detailed Bird (2003 52 present-day Euler pole set (relative to a fixed Pacific plate for the Earth's surface, after conversion to absolute Euler poles. Additionally, new analytical results now provide new details on upper mantle mass anomalies in the outer 200 km of the Earth, as well as an initial quantizing of surface deformations.
Pseudospin and nuclear deformation
International Nuclear Information System (INIS)
An operator which effects the transformation to the pseudospin representation within the oscillator shell model at arbitrary triaxial deformation is constructed as a special projection of the momentum helicity operator. Since the exact transformation of many important operators cannot be performed in a closed analytical form, a procedure of approximate transformation is developed. In the spherical and asymptotic prolate limits the transforms thus derived reduce to the known exact results. The approximate transform of a modified Nilsson Hamiltonian is found to be almost indistinguishable from the ''pseudo'' Hamiltonian with the strongly reduced spin-orbit strength. (orig.)
Kuriki, R.; Ogushi, S.; Sugamoto, A.
1998-01-01
We attempt to construct new superstring actions with a $D$-plet of Majorana fermions $\\psi^{\\cal B}_A$, where ${\\cal B}$ is the $D$ dimensional space-time index and $A$ is the two dimensional spinor index, by deforming the Schild action. As a result, we propose three kinds of actions: the first is invariant under N=1 (the world-sheet) supersymmetry transformation and the area-preserving diffeomorphism. The second contains the Yukawa type interaction. The last possesses some ...
Deformed hyperbolic black holes
Chen, Yu; Lim, Yen-Kheng; Teo, Edward
2015-01-01
Black holes with planar or hyperbolic horizons are known to exist in AdS space, alongside the usual ones with spherical horizons. In this paper, we consider a one-parameter generalisation of these black holes that is contained in the AdS C-metric. In terms of the domain-structure analysis recently developed for such solutions, these black holes have a domain in the shape of a triangle. It is shown that the horizons of these black holes are deformed hyperbolic spaces, with th...
Joining by plastic deformation
DEFF Research Database (Denmark)
Mori, Ken-ichiro; Bay, Niels
2013-01-01
As the scale and complexity of products such as aircraft and cars increase, demand for new functional processes to join mechanical parts grows. The use of plastic deformation for joining parts potentially offers improved accuracy, reliability and environmental safety as well as creating opportunities to design new products through joining dissimilar materials. This paper aims to provide an overview of the state of the art in such joining processes, including cold welding, friction stir welding, self-pierce riveting, mechanical clinching and joining by forming. The paper includes description of the mechanism of joint formation, and analysis of joint performance and applicability. © 2013 CIRP.
Deformations of holomorphic Lagrangian fibrations
Sawon, J
2005-01-01
Let $X\\to\\P^n$ be a $2n$-dimensional projective holomorphic symplectic manifold admitting a Lagrangian fibration over $\\P^n$. Matsushita proved that the fibration can be deformed in a codimension one family in the moduli space $\\mathrm{Def}(X)$ of deformations of $X$. We extend his result by proving that if the Lagrangian fibration admits a section, then there is a codimension two family of deformations which also preserve the section.
Deformation behaviour of dispersion hardened nanocrystalline copper
Directory of Open Access Journals (Sweden)
J.P. Stobrawa
2006-04-01
Full Text Available Purpose: The aim of this work was to describe deformation behaviour of nanocrystalline copper dispersion-hardened with nanoparticles of tungsten carbide and yttria.Design/methodology/approach: Tests were made with the Cu, Cu-WC and Cu-Y2O3 micro-composites containing up to 3 % of a hardening phase. These were obtained by powder metallurgy techniques, i.e. milling the input powders in the planetary ball mills, compacting and sintering. The mechanical properties (hardness, 0,2 YS, elongation during compression test and microstructure were examined by the optical, scanning and transmission electron microscopy.Findings: Analysis of the initial nanocrystalline structure of these materials was made, and its evolution during deformation process was investigated with an account of the hardening effect and the changes in the mechanical and plastic properties. Results of this analysis have been discussed based on the existing theories related to hardening of nanocrystalline materials.Research limitations/implications: The powder metallurgy techniques make it possible to obtain copper-based bulk materials by means of milling input powders in the planetary ball, followed by compacting and sintering. Additional operations of hot extrusion are also often used. There is some threat, however, that during high-temperature processing or using these materials at elevated or high temperatures this nanometric structure may become unstable. The studies have shown the importance of “flows” in the consolidated materials such as pores or regions of poor powder particles joining which significantly deteriorate mechanical properties of compacted and sintered powder micro composites.Practical implications: A growing trend to use new copper-based functional materials is observed recently world-wide. Within this group of materials particular attention is drawn to those with nanometric grain size of a copper matrix, which exhibit higher mechanical properties than microcrystalline copper.Originality/value: The paper contributes to the elucidation of deformation behaviour of high-porosity nanocrystalline copper dispersion hardened with tungsten carbide and yttria.
Work-Hardening and Deformation Mechanism of Cold Rolled Low Carbon Steel
Wang Su-Fen; Peng Yan; Li Zhi-Jie
2013-01-01
The study reports the mechanical property and microstructure of cold rolled low carbon steel and its work-hardening behavior in the deformation process. The tensile test in room temperature of low carbon steel was implemented for the different cold rolling deformation, the stress-strain curve was draught according to the relationship between strength and deformation and fitted for the polynomial fitting, the strain hardening exponent (n) of test steel was calculated by the Hollomon method. In...
The two-parameter deformation of GL(2), its differential calculus, and Lie algebra
International Nuclear Information System (INIS)
The Yang-Baxter equation is solved in two dimensions giving rise to a two-parameter deformation of GL(2). The transformation properties of quantum planes are briefly discussed. Non-central determinant and inverse are constructed. A right-invariant differential calculus is presented and the role of the different deformation parameters investigated. While the corresponding Lie algebra relations are simply deformed, the comultiplication exhibits both quantization parameters. (orig.)
Chan, Deva D.; Neu, Corey P
2012-01-01
Characterization of spatiotemporal deformation dynamics and material properties requires non-destructive methods to visualize mechanics of materials and biological tissues. Displacement-encoded magnetic resonance imaging (MRI) has emerged as a noninvasive and non-destructive technique used to quantify deformation and strains. However, the techniques are not yet applicable to a broad range of materials and load-bearing tissues. In this paper, we visualize transient and internal material deform...
Transition in the deformation mode of nanocrystalline tantalum processed by high-pressure torsion
International Nuclear Information System (INIS)
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.
Deformation Expression for Elements of Algebra
Omori, H.; Maeda, Y.; Miyazaki, N.; Yoshioka, A.
2011-01-01
The purpose of this paper is to give a notion of deformation of expressions for elements of algebra. Deformation quantization (cf.[BF]) deforms the commutative world to a non-commutative world. However, this involves deformation of expression of elements of algebras even from a commutative world to another commutative world. This is indeed a deformation of expressions for elements of algebra.
Shear stress-induced improvement of red blood cell deformability.
Meram, Ece; Yilmaz, Bahar D; Bas, Ceren; Atac, Nazl?; Yalcin, O; Meiselman, Herbert J; Baskurt, Oguz K
2013-01-01
Classically, it is known that red blood cell (RBC) deformability is determined by the geometric and material properties of these cells. Experimental evidence accumulated during the last decade has introduced the concept of active regulation of RBC deformability. This regulation is mainly related to altered associations between membrane skeletal proteins and integral proteins, with the latter serving to anchor the skeleton to the lipid matrix. It has been hypothesized that shear stress induces alterations of RBC deformability: the current study investigated the dynamics of the transient improvement in deformability induced by shear stress at physiologically-relevant levels. RBC were exposed to various levels of shear stress (SS) in a Couette type shearing system that is part of an ektacytometer, thus permitting the changes in RBC deformability during the application of SS to be monitored. Initial studies showed that there is an increase in deformability of the RBC subjected to SS in the range of 5-20 Pa, with kinetics characterized by time constants of a few seconds. Such improvement in deformability, expressed by an elongation index (EI), was faster with higher levels of SS and hence yielded shorter time constants: absolute values of EI increased by 3-8% of the starting level. Upon the removal of the shear stress, this response by RBC was reversible with a slower time course compared to the increase in EI during application of SS. Increased calcium concentration in the RBC suspending medium prevented the improvement of deformability. It is suggested that the improvement of RBC deformability by shear forces may have significant effects on blood flow dynamics, at least in tissues supplied by blood vessels with impaired vasomotor reserve, and may therefore serve as a compensating mechanism for the maintenance of adequate microcirculatory perfusion. PMID:23863281
Energy Technology Data Exchange (ETDEWEB)
Wrzesinski, J.; Broda, R.; Fornal, B.; Krolas, W.; Pawlat, T. [Niewodniczanski Institute of Nuclear Physics, PL-31-342, Krakow (Poland); Carpenter, M.P.; Janssens, R.V.F.; Seweryniak, D. [Physics Division, Argonne National Laboratory, IL 60439, Argonne (United States); Lunardi, S.; Ur, C.A.; Viesti, G. [Dipartimento di Fisica dell' Universita and INFN Sezione di Padova, I-35131, Padova (Italy); Cinausero, M.; Marginean, N. [INFN Laboratori Nazionali di Legnaro, I-35020, Legnaro (Italy); Maier, K.H. [Hahn-Meitner Institute, D-14109, Berlin (Germany)
2004-04-01
New high-spin states were identified in the {sup 205}Tl isotope produced in deep-inelastic heavy-ion reactions. The expected 29/2{sup +} yrast state and 35/2{sup -} isomeric state with 235 ns half-life were located above the 2.6 {mu}s isomer known from previous studies. Above this isomer a 7092 keV level was interpreted as a 41/2{sup +} state arising from the coupling of the octupole vibration of the {sup 208}Pb core with the three-hole structure of the 35/2{sup -} isomer. (orig.)
Baxter operators with deformed symmetry
Chicherin, D; Karakhanyan, D; Kirschner, R
2012-01-01
Baxter operators are constructed for quantum spin chains with deformed $s\\ell_2$ symmetry. The parallel treatment of Yang-Baxter operators for the cases of undeformed, trigonometrically and elliptically deformed symmetries presented earlier and relying on the factorization regarding parameter permutations is extended to the global chain operators following the scheme worked out recently in the undeformed case.
Baxter operators with deformed symmetry
Chicherin, D.; Derkachov, S.; Karakhanyan, D.; Kirschner, R.
2013-03-01
Baxter operators are constructed for quantum spin chains with deformed s?2 symmetry. The parallel treatment of Yang-Baxter operators for the cases of undeformed, trigonometrically and elliptically deformed symmetries presented earlier and relying on the factorization regarding parameter permutations is extended to the global chain operators following the scheme worked out recently in the undeformed case.
Baxter operators with deformed symmetry
Energy Technology Data Exchange (ETDEWEB)
Chicherin, D., E-mail: chicherin@pdmi.ras.ru [Chebyshev Laboratory, St. Petersburg State University, 14th line 29b, 199178 St. Petersburg (Russian Federation); St. Petersburg Department of Steklov Mathematical Institute of Russian Academy of Sciences, Fontanka 27, 191023 St. Petersburg (Russian Federation); Derkachov, S., E-mail: derkach@pdmi.ras.ru [St. Petersburg Department of Steklov Mathematical Institute of Russian Academy of Sciences, Fontanka 27, 191023 St. Petersburg (Russian Federation); Karakhanyan, D., E-mail: karakhan@lx2.yerphi.am [Yerevan Physics Institute, Br. Alikhanian st. 2, Yerevan, 0036 (Armenia); Yerevan State University, 1 Alex Manoogian st., Yerevan, 0025 (Armenia); Kirschner, R., E-mail: Roland.Kirschner@itp.uni-leipzig.de [Institut fuer Theoretische Physik, Universitaet Leipzig, PF 100 920, 04009 Leipzig (Germany)
2013-03-21
Baxter operators are constructed for quantum spin chains with deformed s Script-Small-L {sub 2} symmetry. The parallel treatment of Yang-Baxter operators for the cases of undeformed, trigonometrically and elliptically deformed symmetries presented earlier and relying on the factorization regarding parameter permutations is extended to the global chain operators following the scheme worked out recently in the undeformed case.
Baxter operators with deformed symmetry
International Nuclear Information System (INIS)
Baxter operators are constructed for quantum spin chains with deformed s?2 symmetry. The parallel treatment of Yang–Baxter operators for the cases of undeformed, trigonometrically and elliptically deformed symmetries presented earlier and relying on the factorization regarding parameter permutations is extended to the global chain operators following the scheme worked out recently in the undeformed case.
Fraktalnist deformational relief polycrystalline aluminum
Directory of Open Access Journals (Sweden)
?.?. ??????????
2006-02-01
Full Text Available The possibility of the fractal geometry method application for the analisys of surface deformation structures under cyclic loading is presented.It is shown, that deformation relief of the alclad aluminium alloyes meets the criteria of the fractality. For the fractal demention estimation the method of “box-counting”can be applied.
[Rheumatic forefoot deformities].
Fuhrmann, R
2014-11-01
The frequency and extent of rheumatic forefoot deformities have been greatly reduced since the introduction of disease-modifying antirheumatic drugs (DMARD). The accompanying reduction in arthritic destruction of joints opens up new treatment options whereby priority is given to joint preservation. This is true for the first middle foot ray as well as for the small toe rays. Whereas resection arthroplasty of the metatarsophalangeal joints II-V was previously considered the gold standard treatment, joint-preserving operative procedures (e.g. metatarsal osteotomy and periarticular soft tissue interventions) are now being increasingly more propagated. Resection arthroplasty of the first midfoot ray has major biomechanical disadvantages so that it is not surprising that reconstructive procedures are given priority. In patients with severe arthritic destruction of the first metatarsophalangeal joint, arthrodesis has substantial biomechanical advantages compared to resection arthroplasty. Nevertheless, it has not yet been confirmed that fusion leads to superior clinical results. PMID:25269874
Identification of timber deformations
Francini, Franco; Longobardi, Giuseppe; Sansoni, Paola; Euzzor, Stefano; Ciamberlini, Claudio
2002-11-01
A system to assess timber deformations has been developed using an array of optical distance sensors (ODS), each of which controls a strip of the timber determining how it deviates from flatness. The main characteristics of the ODS system are compactness, modularity and real-time elaboration software. The shape of the timber is reconstructed by sampling the distance between the timber and the ODS while the timber is running in the wood plant. The working principle of the ODS is based on the triangulation of a light spot. A low-power laser diode projects a light spot on the timber surface. The image of the spot moves on a position-sensitive detector (PSD) according to the distance between the optical system and the timber. Suitable software for computer-aided operation was developed at an industrial plant producing wood cutting systems. A prototype of the ODS system has been constructed and tested under real operating conditions.
International Nuclear Information System (INIS)
Load relaxation properties of unirradiated Zircaloy nuclear fuel claddings were measured at 648 K. Deformation paths preceding the relaxation were altered in order to study the factors affecting relaxation properties. The histories chosen were constant strain rate tensile deformation, constant load creep deformation, and biaxial followed by uniaxial creep. Stress versus time records were obtained from the relaxation runs. Stress versus strain rate curves were further derived and effects of prior strain rate, strain, transient deformation and strain hardening on relaxation properties are discussed. It was found from the experimental results that after strain hardening and transient deformation saturates, the strain rate just prior to relaxation has a major effect on the stress versus strain rate characteristics. This finding holds both for the relaxation after tension and creep. Existing models could not describe these findings
Near real-time skin deformation mapping
Kacenjar, Steve; Chen, Suzie; Jafri, Madiha; Wall, Brian; Pedersen, Richard; Bezozo, Richard
2013-02-01
A novel in vivo approach is described that provides large area mapping of the mechanical properties of the skin in human patients. Such information is important in the understanding of skin health, cosmetic surgery[1], aging, and impacts of sun exposure. Currently, several methods have been developed to estimate the local biomechanical properties of the skin, including the use of a physical biopsy of local areas of the skin (in vitro methods) [2, 3, and 4], and also the use of non-invasive methods (in vivo) [5, 6, and 7]. All such methods examine localized areas of the skin. Our approach examines the local elastic properties via the generation of field displacement maps of the skin created using time-sequence imaging [9] with 2D digital imaging correlation (DIC) [10]. In this approach, large areas of the skin are reviewed rapidly, and skin displacement maps are generated showing the contour maps of skin deformation. These maps are then used to precisely register skin images for purposes of diagnostic comparison. This paper reports on our mapping and registration approach, and demonstrates its ability to accurately measure the skin deformation through a described nulling interpolation process. The result of local translational DIC alignment is compared using this interpolation process. The effectiveness of the approach is reported in terms of residual RMS, image entropy measures, and differential segmented regional errors.
Deformation of Man Made Objects
Ibrahim, Mohamed
2012-07-01
We introduce a framework for 3D object deformation with primary focus on man-made objects. Our framework enables a user to deform a model while preserving its defining characteristics. Moreover, our framework enables a user to set constraints on a model to keep its most significant features intact after the deformation process. Our framework supports a semi-automatic constraint setting environment, where some constraints could be automatically set by the framework while others are left for the user to specify. Our framework has several advantages over some state of the art deformation techniques in that it enables a user to add new features to the deformed model while keeping its general look similar to the input model. In addition, our framework enables the rotation and extrusion of different parts of a model.
Transverse deformations of extreme horizons
Li, Carmen
2015-01-01
We consider the inverse problem of determining all extreme black hole solutions to the Einstein equations with a prescribed near-horizon geometry. We investigate this problem by considering infinitesimal deformations of the near-horizon geometry along transverse null geodesics. We show that, up to a gauge transformation, the linearised Einstein equations reduce to an elliptic PDE for the extrinsic curvature of a cross-section of the horizon. We deduce that for a given near-horizon geometry there exists a finite dimensional moduli space of infinitesimal transverse deformations. We then establish a uniqueness theorem for transverse deformations of the extreme Kerr horizon. In particular, we prove that the only smooth axisymmetric transverse deformation of the near-horizon geometry of extreme Kerr, such that cross-sections of the horizon are marginally trapped surfaces, corresponds to that of the extreme Kerr black hole. Furthermore, we determine all smooth and biaxisymmetric transverse deformations of the near-...
Drop deformation by laser-pulse impact
Gelderblom, Hanneke; Klein, Alexander L; Bouwhuis, Wilco; Lohse, Detlef; Villermaux, Emmanuel; Snoeijer, Jacco H
2015-01-01
A free-falling absorbing liquid drop hit by a nanosecond laser-pulse experiences a strong recoil-pressure kick. As a consequence, the drop propels forward and deforms into a thin sheet which eventually fragments. We study how the drop deformation depends on the pulse shape and drop properties. We first derive the velocity field inside the drop on the timescale of the pressure pulse, when the drop is still spherical. This yields the kinetic-energy partition inside the drop, which precisely measures the deformation rate with respect to the propulsion rate, before surface tension comes into play. On the timescale where surface tension is important the drop has evolved into a thin sheet. Its expansion dynamics is described with a slender-slope model, which uses the impulsive energy-partition as an initial condition. Completed with boundary integral simulations, this two-stage model explains the entire drop dynamics and its dependance on the pulse shape: for a given propulsion, a tightly focused pulse results in a...
Deformation behaviour of dispersion hardened nanocrystalline copper
J.P. Stobrawa; Z.M. Rdzawski
2006-01-01
Purpose: The aim of this work was to describe deformation behaviour of nanocrystalline copper dispersion-hardened with nanoparticles of tungsten carbide and yttria.Design/methodology/approach: Tests were made with the Cu, Cu-WC and Cu-Y2O3 micro-composites containing up to 3 % of a hardening phase. These were obtained by powder metallurgy techniques, i.e. milling the input powders in the planetary ball mills, compacting and sintering. The mechanical properties (hardness, 0,2 YS, elongation du...
Phase strength effects on chemical mixing in extensively deformed alloys
International Nuclear Information System (INIS)
Forced chemical mixing during extensive straining requires that the constituent phases co-deform, and is therefore a sensitive function of their mechanical properties, particularly strength. To develop a quantitative understanding of such phase strength effects on co-deformation and steady-state chemical mixity during severe deformation processing, we studied several tungsten–transition metal couples with a range of differences in strength during a process of mechanical alloying in a high-energy ball mill. Changes in the powders’ microstructures, mechanical properties and chemical mixing revealed two distinct behaviors: alloys either chemically homogenized or remained dual phase, depending on the relative strengths of the base alloying elements. A kinetic Monte Carlo simulation of mechanical alloying that accounts for a phase strength mismatch reproduced the experimentally observed behaviors, and provides quantitative insight into the combination of material and processing parameters that control mechanical mixing
Shape Changing Nonlocal Molecular Deformations in a Nematic Liquid Crystal
International Nuclear Information System (INIS)
The nature of nonlinear molecular deformations in a homeotropically aligned nematic liquid crystal (NLC) is presented. We start from the basic dynamical equation for the director axis of a NLC with elastic deformation mapped onto an integro-differential perturbed Nonlinear Schroedinger equation which includes the nonlocal term. By invoking the modified extended tangent hyperbolic function method aided with symbolic computation, we obtain a series of solitary wave solutions. Under the influence of the nonlocality induced by the reorientation nonlinearity due to fluctuations in the molecular orientation, the solitary wave exhibits shape changing property for different choices of parameters. This intriguing property, as a result of the relation between the coherence of the solitary deformation and the nonlocality, reveals a strong need for deeper understanding in the theory of self-localization in NLC systems. (author)
Physical Significance of q Deformation and Many-Body Interactions in Nuclei
Sviratcheva, K D; Georgieva, A I; Draayer, J P
2004-01-01
The quantum deformation concept is applied to a study of pairing correlations in nuclei with mass 40properties and fine structure effects, the results show that the q deformation plays a significant role in understanding higher-order effects in the many-body interaction.
Physical significance of q deformation and many-body interactions in nuclei
International Nuclear Information System (INIS)
The quantum deformation concept is applied to a study of pairing correlations in nuclei with mass 40?A?100. While the nondeformed limit of the theory provides a reasonable overall description of certain nuclear properties and fine structure effects, the results show that the q deformation plays a significant role in understanding higher-order effects in the many-body interaction
MM97.48 Influence of multidirectional deformation mode on flow stress behaviour during cold forming
DEFF Research Database (Denmark)
Lindegren, Maria; Pavel, Huml
1997-01-01
In the present experimental investigation the influence of strain path on behaviour and final properties has been simulated in uni-, two- and three-directional deformation regimes. Pure iron and a low carbon steel have been investigated considering stress strain behaviour. Brass and copper specimens which have been undergoing alternate cyclic deformations have been evaluated by hardness measurements, grain size estimation and TEM.
Fluctuations and All-In-All-Out Ordering in Dipole-Octupole Nd_{2}Zr_{2}O_{7}.
Lhotel, E; Petit, S; Guitteny, S; Florea, O; Ciomaga Hatnean, M; Colin, C; Ressouche, E; Lees, M R; Balakrishnan, G
2015-11-01
By means of neutron scattering and magnetization measurements down to 90 mK, we determine the magnetic ground state of the spin-ice candidate Nd_{2}Zr_{2}O_{7}. We show that, despite ferromagnetic interactions, Nd_{2}Zr_{2}O_{7} undergoes a transition around 285 mK towards an all-in-all-out antiferromagnetic state, with a strongly reduced ordered magnetic moment. We establish the (H,T) phase diagram in the three directions of the applied field and reveal a metamagnetic transition around 0.1 T, associated with an unexpected shape of the magnetization curves. We propose that this behavior results from the peculiar nature of the Nd^{3+} doublet, a dipolar-octupolar doublet, different from the standard Kramers doublet studied to date, thus revealing the importance of multipolar correlations in the properties of pyrochlore oxides. PMID:26588409
Fluctuations and All-In-All-Out Ordering in Dipole-Octupole Nd2Zr2O7
Lhotel, E.; Petit, S.; Guitteny, S.; Florea, O.; Ciomaga Hatnean, M.; Colin, C.; Ressouche, E.; Lees, M. R.; Balakrishnan, G.
2015-11-01
By means of neutron scattering and magnetization measurements down to 90 mK, we determine the magnetic ground state of the spin-ice candidate Nd2Zr2O7. We show that, despite ferromagnetic interactions, Nd2Zr2O7 undergoes a transition around 285 mK towards an all-in-all-out antiferromagnetic state, with a strongly reduced ordered magnetic moment. We establish the (H ,T ) phase diagram in the three directions of the applied field and reveal a metamagnetic transition around 0.1 T, associated with an unexpected shape of the magnetization curves. We propose that this behavior results from the peculiar nature of the Nd3 + doublet, a dipolar-octupolar doublet, different from the standard Kramers doublet studied to date, thus revealing the importance of multipolar correlations in the properties of pyrochlore oxides.
International Nuclear Information System (INIS)
The role of different deformation mechanisms in controlling mechanical properties were studied in two low-Ni, Cr–Mn austenitic stainless steel grades (Types 201 and 201L) by tensile testing and microstructure examinations. Tensile tests were carried out at two different strain rates, 5×10?4 and 10?2 s?1, in the temperature range from ?80 °C to 200 °C. It was observed that the flow properties and work hardening rate are affected significantly by temperature and strain rate for the concerned steels through variation of deformation mechanism. Deformation-induced austenite-to-martensite transformation (TRIP effect) is the dominant mechanism at temperatures below room temperature. From 50 °C up to 200 °C, plastic deformation is controlled by mechanical twinning (TWIP effect) and dislocation glide. The electron backscattered diffraction (EBSD) technique and transmission electron microscopy (TEM) were employed to study the plastic deformation accommodation and identify the primary deformation mechanisms operating in the deformed steels.
Deformation of Laminar Round Liquid Jets in Uniform Fluid Crossflows
Aalburg, Christian; Faeth, Gerard M.; van Leer, Bram
2000-11-01
The deformation and drag properties of laminar round liquid jets in uniform crossflows of fluids having smaller densities were studied computationally. Effects of liquid-jet/ambient-fluid density ratio (in the range 2-64), liquid-viscous/surface-tension force ratio (Ohnesorge range of 0.001-10) and crossflow Reynolds numbers (up to 100) were emphasized in order to address conditions relevant to high-pressure combusting sprays. Predictions of deformation and drag properties were in good agreement with recent measurements. It was found that increased effects of liquid viscosity (increased Ohnesorge numbers) inhibited deformation and required progressively larger drag disturbances (larger Weber numbers) to initiate breakup, very similar to the secondary breakup properties of drops. The liquid-jet/ambient-fluid density ratio, and the presence of attached recirculation regions in the wake of the liquid jet (or Reynolds number) had surprisingly little effect on liquid jet deformation and breakup properties. Similar to drops, the liquid jets oscillated at small Ohnesorge numbers but this motion was damped as Ohnesorge numbers increased.
Deformation theory of objects in homotopy and derived categories I: general theory
Efimov, Alexander I.; Lunts, Valery A.; Orlov, Dmitri O.
2007-01-01
This is the first paper in a series. We develop a general deformation theory of objects in homotopy and derived categories of DG categories. Namely, for a DG module $E$ over a DG category we define four deformation functors $\\Def ^{\\h}(E)$, $\\coDef ^{\\h}(E)$, $\\Def (E)$, $\\coDef (E)$. The first two functors describe the deformations (and co-deformations) of $E$ in the homotopy category, and the last two - in the derived category. We study their properties and relations. Thes...
The q-deformed Jaynes-Cummings Model and its q-Supercoherent States
Hao, San-Ru; Wang, Lu-Ya
2001-01-01
In this paper, we have proposed a q-deformed Jaynes-Cummings(JC) model and constructed the q-SuperCoherent States(q-SCSs) for the q-deformed JC model. We have also discussed the properties of the q-supercoherent states and given the completeness relation expression. The representation of the q-supercoherent states for the q-deformed JC model is studied as well. PACS number(s): 03.65.Nk Key Works: q-deformed JC model, q-supercoherent states,q-SCSs representation.
International Nuclear Information System (INIS)
Experimental results of studying the characteristics of crystal defects in cold-deformed nickel prepared by the method of measuring residual specific electric resistance, are presented. Subgrain regions in nickel deformed at low temperatures at specific deformation degrees can be considered as a metastable phase close to amorphous one which has the highest density of dislocations. Violations of the monotonous alteration of residual specific electric resistance and other properties observed at specific deformation degrees can be explained by local phase transitions from a crystal state into that amorphous, and vice versa
Deformation theory of objects in homotopy and derived categories I: general theory
Lunts, V A; Lunts, Valery A.; Orlov, Dmitri
2007-01-01
This is the first paper in a series. We develop a general deformation theory of objects in homotopy and derived categories of DG categories. Namely, for a DG module $E$ over a DG category we define four deformation functors $\\Def ^{\\h}(E)$, $\\coDef ^{\\h}(E)$, $\\Def (E)$, $\\coDef (E)$. The first two functors describe the deformations (and co-deformations) of $E$ in the homotopy category, and the last two - in the derived category. We study their properties and relations. These functors are defined on the category of artinian (not necessarily commutative) DG algebras.
Deformation twinning in a creep-deformed nanolaminate structure.
Hsiung, Luke L
2010-10-01
The underlying mechanism of deformation twinning occurring in a TiAl-(?)/Ti(3)Al-(?(2)) nanolaminate creep deformed at elevated temperatures has been studied. Since the multiplication and propagation of lattice dislocations in both ? and ?(2) thin lamellae are very limited, the total flow of lattice dislocations becomes insufficient to accommodate the accumulated creep strains. Consequently, the movement of interfacial dislocations along the laminate interfaces, i.e., interface sliding, becomes an alternative deformation mode of the nanolaminate structure. Pile-ups of interfacial dislocations occur when interfacial ledges and impinged lattice dislocations act as obstacles to impede the movement of interfacial dislocations. Deformation twinning can accordingly take place to relieve a stress concentration resulting from the pile-up of interfacial dislocations. An interface-controlled twinning mechanism driven by the pile-up and dissociation of interfacial dislocations is accordingly proposed. PMID:21403216
Deformation techniques for sparse systems
Jeronimo, G; Solerno, P; Waissbein, A; Jeronimo, Gabriela; Matera, Guillermo; Solerno, Pablo; Waissbein, Ariel
2006-01-01
We exhibit a probabilistic symbolic algorithm for solving zero-dimensional sparse systems. Our algorithm combines a symbolic homotopy procedure, based on a flat deformation of a certain morphism of affine varieties, with the polyhedral deformation of Huber and Sturmfels. The complexity of our algorithm is quadratic in the size of the combinatorial structure of the input system. This size is mainly represented by the mixed volume of Newton polytopes of the input polynomials and an arithmetic analogue of the mixed volume associated to the deformations under consideration.
Structure of the copper under controlled deformation path conditions
Directory of Open Access Journals (Sweden)
G. Niewielski
2009-03-01
Full Text Available Purpose: One of the methods of plastic deformation under complex deformation path conditions is compression with oscillatory torsion. The observable effects in the form of changing force parameters and structure changes confirm the possibility of deformation to a value many times higher than in the case of methods traditionally applied for forming. This article presents the results of the influence of compression with oscillatory torsion on structural phenomena occurring in copper deformed in such a way.Design/methodology/approach: The examinations were conducted at a compression/oscillatory torsion test stand. The structural examinations were conducted with the use of light and electron microscopy.Findings: In experimental investigations, a reduction of unit pressures was observed when compared to conventional compression. The structural examinations indicated substantial differences in the mechanisms of plastic deformation conducted in both conventional and combined way.Research limitations/implications: There are premises which show that a metallic material of a nanometric structure can be obtained in this way (top-down method, by the accumulation of great plastic deformation. Metallic materials characterized by grain size below 100nm are distinguished by unconventional properties. Further examinations should focus on conducting experiments in a way that would enable grain size reduction to a nanometric size. This will enable the cumulation of greater deformation in the material.Originality/value: The method of compression with oscillatory torsion is an original method developed at the Silesian University of Technology, owing to which it is possible to obtain high deformation values (SPD without risking the loss of cohesion of the material. Thorough understanding of the changes taking place in the structure of metals subjected to compression with oscillatory torsion will allow the optimal choice of process parameters in order to achieve a gradual grain size reduction.
A study on laser welding deformation of 304 stainless steel
International Nuclear Information System (INIS)
In heavy industries, 304 austenitic stainless steel is the most popular material which is used for nuclear equipment, chemical vessels, vacuum vessels and so on. On the fabrication, not only a joint quality but also severe dimensional accuracy is required. To keep dimensional accuracy, considerable cost and efforts are requested, because the welding deformation of austenitic stainless steel is deeply depended on the physical properties of material itself. To decrease welding deformation, big jigs or water cooling method are commonly used which lead to the high cost. In general, the fusion welding by high energy density heat source results in less distortion. Today, laser welding technology has grown up to the stage that enables to weld thick plate with small deformation. The researches of welding deformation have been conducted intensively, but they are mainly concerned for arc welding, and studies for laser welding are very few. In this report, the authors will show the test results of deformation behavior in laser welding of 304 stainless steel. Also, they will discuss the deformation behavior comparing to that in arc welding. The main results of this study are as follows. 1. The angular distortion of laser welding can be unified by heat input parameter (Hp) which is used for arc welding deformation. 2. The angular distortion are same under the condition of Hp3 in spite of different welding method, however under the condition of Hp>6-9 J/mm3 the angular distortion is quite different depending on the power density of welding method. 3. Pure angular distortion seemed to complete just after welding, but following longitudinal distortion took place for long period. 4. The critical value of longitudinal distortion can be estimated from heat input parameter. The transverse deformation can be also estimated by heat input parameter. (author)
Carbon sequestration in coal-beds with structural deformation effects
International Nuclear Information System (INIS)
Carbon dioxide sequestration in a coal-bed is a profitable method to reduce the concentration of greenhouse gas in the atmosphere and to recover byproduct methane from the coal seam. The important factor to be considered is the stability of the coal-bed with the increased carbon dioxide injection. It is crucial to avoid carbon dioxide escaping from the coal seam caused by structural deformation. Meanwhile, structural deformation also depends on such properties of the geological coal basin as fracture state and phase equilibrium, especially the porosity, permeability and saturation of the coal seam. In this study, a structural deformation effect was simulated with the purpose of predicting carbon dioxide storage in the environment of a typical unmineable coal seam. As an example, Appalachian Basin is considered in the deformation analysis of carbon dioxide sequestration based on the variable saturation model. Moreover, the comparison between simulations with and without the account of structural deformation is given. The results indicate that modeling of structural deformation in carbon sequestration is feasible by directly coupling structure terms to a variable saturated model. Moreover, introducing structural deformation effects into carbon sequestration modeling is important because it affects the fluid flow and leads to a faster drop of the resulting capillary pressure and relative permeability of the gas phase. This faster drop directly results in the diminished carbon dioxide storage capacity in a coal-bed basin. In addition, structural deformation modeling in carbon sequestration simulations can provide important insights into how to avoid carbon leakage and seepage by monitoring the effective stress and displacement of coal-bed basin during carbon dioxide injection.
The role of crustal quartz in controlling Cordilleran deformation.
Lowry, Anthony R; Pérez-Gussinyé, Marta
2011-03-17
Large-scale deformation of continents remains poorly understood more than 40 years after the plate tectonic revolution. Rock flow strength and mass density variations both contribute to stress, so both are certain to be important, but these depend (somewhat nebulously) on rock type, temperature and whether or not unbound water is present. Hence, it is unclear precisely how Earth material properties translate to continental deformation zones ranging from tens to thousands of kilometres in width, why deforming zones are sometimes interspersed with non-deforming blocks and why large earthquakes occasionally rupture in otherwise stable continental interiors. An important clue comes from observations that mountain belts and rift zones cyclically form at the same locations despite separation across vast gulfs of time (dubbed the Wilson tectonic cycle), accompanied by inversion of extensional basins and reactivation of faults and other structures formed in previous deformation events. Here we show that the abundance of crustal quartz, the weakest mineral in continental rocks, may strongly condition continental temperature and deformation. We use EarthScope seismic receiver functions, gravity and surface heat flow measurements to estimate thickness and seismic velocity ratio, v(P)/v(S), of continental crust in the western United States. The ratio v(P)/v(S) is relatively insensitive to temperature but very sensitive to quartz abundance. Our results demonstrate a surprising correlation of low crustal v(P)/v(S) with both higher lithospheric temperature and deformation of the Cordillera, the mountainous region of the western United States. The most plausible explanation for the relationship to temperature is a robust dynamical feedback, in which ductile strain first localizes in relatively weak, quartz-rich crust, and then initiates processes that promote advective warming, hydration and further weakening. The feedback mechanism proposed here would not only explain stationarity and spatial distributions of deformation, but also lend insight into the timing and distribution of thermal uplift and observations of deep-derived fluids in springs. PMID:21412337
Surface processes and deformation in orogenic settings : quantification and modeling
Steer, Philippe
2010-01-01
Among erosion processes, river incision is classicaly described as a key process controlling erosion of landscapes. Incision efficiency is mainly influenced by climate and erodibility. This latter is not only dependent on the nature of the bedrock, but also on its past deformation, which affects its rheological effective properties, such as fracture density. The main objectives of this thesis are: (1) to better constrain the relationship between effective properties and erodibility, and (2) t...
International Nuclear Information System (INIS)
Dissimilar Channel Angular Pressing (DCAP) is a severe plastic deformation technique to improve the mechanical properties of flat products by producing ultrafine grains. In this study, the changes in the microstructure and mechanical properties of 6061 Al-alloy strips deformed by various numbers of DCAP passes were investigated. Some DCAPed samples were also held at 200 deg. C and 350 deg. C to investigate the effect of post-annealing. Mechanical properties were determined by hardness and tension tests; and microstructural changes were investigated by TEM analysis. Up to a critical level of plastic strain, remarkable improvements have been observed in the strength and hardness of the severely deformed strips; and the improvements have been explained by variations in grain size, dislocation structure, and formation of subgrains. - Research Highlights: ?Dissimilar Channel Angular Pressing (DCAP). ?Severe plastic deformation (SPD). ?Transmission Electron Microscopy of the 6061 Al alloy. ?Mechanical Properties of 6061 Al alloy.
Plastic Deformation of Metal Surfaces
DEFF Research Database (Denmark)
Hansen, Niels; Zhang, Xiaodan
2013-01-01
Plastic deformation of metal surfaces by sliding and abrasion between moving parts can be detrimental. However, when the plastic deformation is controlled for example by applying different peening techniques hard surfaces can be produced which can increase the fracture resistance and fatigue life of metal components. An optimization of processes and material parameters must be based on a quantification of stress and strain gradients at the surface and in near surface layer where the structural scale can reach few tens of nanometers. For such fine structures it is suggested to quantify structural parameters by TEM and EBSD and apply strength-structural relationships established for the bulk metal deformed to high strains. This technique has been applied to steel deformed by high energy shot peening and a calculated stress gradient at or near the surface has been successfully validated by hardness measurements as a function of distance from the surface.
Nonlinear Deformable-body Dynamics
Luo, Albert C J
2010-01-01
"Nonlinear Deformable-body Dynamics" mainly consists in a mathematical treatise of approximate theories for thin deformable bodies, including cables, beams, rods, webs, membranes, plates, and shells. The intent of the book is to stimulate more research in the area of nonlinear deformable-body dynamics not only because of the unsolved theoretical puzzles it presents but also because of its wide spectrum of applications. For instance, the theories for soft webs and rod-reinforced soft structures can be applied to biomechanics for DNA and living tissues, and the nonlinear theory of deformable bodies, based on the Kirchhoff assumptions, is a special case discussed. This book can serve as a reference work for researchers and a textbook for senior and postgraduate students in physics, mathematics, engineering and biophysics. Dr. Albert C.J. Luo is a Professor of Mechanical Engineering at Southern Illinois University, Edwardsville, IL, USA. Professor Luo is an internationally recognized scientist in the field of non...
Classification methods for ground deformation
Directory of Open Access Journals (Sweden)
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2007-03-01
Full Text Available Classification for unsafety categories defining of different variants of earth-deformative processes according to factual measurements was adduced. Nomograms of earth failure classification depending on conditions of underground mining were developed.
Numerical Modelling of Overburden Deformations
Directory of Open Access Journals (Sweden)
J. Barták
2002-01-01
Full Text Available This paper focuses on the application and verification of mathematical models of the effect of supporting measures on the reduction of overburden deformations. The study of the behaviour of the models is divided into three parts: reduction of the tunnelling effects on the Minorit monastery by means of a jet-grouting curtain; the behaviour of the Hvíž?alka backfilled tunnel and a numerical analysis of the supporting measures affecting the tunnel deformations of the Mrázovka tunnel in Prague.
International Nuclear Information System (INIS)
Using the techniques developed by Lunin and Maldacena we calculate the supergravity solutions of membranes and five-branes in the presence of a background C-field. All the distinct possible C-field configurations are explored. Decoupling limits for these branes are then described that preserve the deformation leading to families of M-theory brane deformation duals. The decoupled geometry is then explored using probe brane techniques and brane thermodynamics
Plastic Deformation of Metal Surfaces
DEFF Research Database (Denmark)
Hansen, Niels; Zhang, Xiaodan; Huang, Xiaoxu
2013-01-01
Plastic deformation of metal surfaces by sliding and abrasion between moving parts can be detrimental. However, when the plastic deformation is controlled for example by applying different peening techniques hard surfaces can be produced which can increase the fracture resistance and fatigue life of metal components. An optimization of processes and material parameters must be based on a quantification of stress and strain gradients at the surface and in near surface layer where the structural s...
Deterritorializing Drawing - transformation/deformation
DEFF Research Database (Denmark)
Brabrand, Helle
2012-01-01
Abstract The paper questions concepts of transformation and deformation in architectural becoming. Provoked by the role of diagram and transformation dominating actual discussions, I state the role of deformation as an equal category of composing. Deleuze, with Bacon, refers to transformation and deformation as two very different categories. Moves of transformation produce new places or singularities in a series, making a Figure emerge that switches between force and form and between transformation and deformation. Deformation is acted out by sensation, passing from one ‘order’ to another. Bacon criticises figurative as well as abstract painting as passing through the brain and not acting directly upon the senses. Figurative and abstract painting both fail to liberate the Figure, implementing transformation of form, but not attaining deformations of bodies. Bacon, then, is concerned about deformation, about painting the sensation, which is essentially rhythm, making Figure-rhythm relations appear as vibrations that flow through the body - making resonance. Deleuze, with Bergson, argues that art extracts ’a little time in a pure state’ from the everyday repetitions, and thereby opens the capacity of the body to be affected by change. The everyday and the ceremonial body, the ordinary and the aberrant movement – these poles generate a passage rather than a difference from the one to the other: from attitude or position to gesture or kinaesthetic twist. Known from without through perception but also from within by sensations, body ‘images’ are different to all other images. Twisting these body images make a mode of operation of art. The paper will address the above issues discussing modes of operation and appearance of my actual project. Acting in the reality of drawing, the project confront the body, situated in real time and depth, with drawing transforming and deforming time and depth.
Competitive Adsorption of a Two-Component Gas on a Deformable Adsorbent
Usenko, A. S.
2013-01-01
We investigate the competitive adsorption of a two-component gas on the surface of an adsorbent whose adsorption properties vary in adsorption due to the adsorbent deformation. The essential difference of adsorption isotherms for a deformable adsorbent both from the classical Langmuir adsorption isotherms of a two-component gas and from the adsorption isotherms of a one-component gas taking into account variations in adsorption properties of the adsorbent in adsorption is ob...
Non-Isothermal, Multi-phase, Multi-component Flows through Deformable Methane Hydrate Reservoirs
Gupta, Shubhangi; Helmig, Rainer; Wohlmuth, Barbara
2015-01-01
We present a hydro-geomechanical model for subsurface methane hydrate systems. Our model considers kinetic hydrate phase change and non-isothermal, multi-phase, multi-component flow in elastically deforming soils. The model accounts for the effects of hydrate phase change and pore pressure changes on the mechanical properties of the soil, and also for the effect of soil deformation on the fluid-solid interaction properties relevant to reaction and transport processes (e.g., ...
Cohomology theory and deformations of Z2-graded Lie algebras
International Nuclear Information System (INIS)
The algebraic cohomology and the spectral sequences for a Z2-graded Lie algebra are briefly reviewed. The reducibility property of a strongly semisimple Lie superalgebra is established. The role of second and third cohomologies in the deformation of a Lie superalgebra is discussed. Using spectral sequences, the second cohomology of full BRS algebra is shown to be F1 and the third cohomology being trivial implying that osp(1,2) is the only graded Lie algebra obtained by deformation of the full BRS algebra. (author). 12 refs
Microstructures and deformation mechanisms of experimentally deformed gabbro
Zhou, Yongsheng; He, Changrong
2015-04-01
The natural gabbro samples were deformed at temperature ranging from 700 to 1150 °C with strain rate steps of 1 × 10-4, 2.5 × 10-5, 6.3 × 10-6 s-1. The mechanical data show that sample experiences gradual transition from semi-brittle flow to plastic flow, corresponding to a systematically decreasing stress exponent n with the increasing temperature ranging from 16.5 to 4.1 (He et al. Sci China (D) 46(7):730-742, 2003). We investigate microstructures and deformation mechanisms of experimentally deformed gabbro under transmission electron microscope in this study. For low temperature of 700 °C to 950 °C, the deformation is mainly accommodated with dislocation glide and mechanical twinning, corresponding to stress exponent lager than 5, which means semi-brittle deformation. Whereas with higher temperature up to 1000 °C-1150 °C, the deformation is accommodated mainly with dislocation glide and climb corresponding to stress exponent of 4.1, which means plastic deformation. Evidence of dislocation climb has been found as dislocation walls in plagioclase. The observed slip system in plagioclase is (001)1/2[110] and that in clinopyroxene are (100)[001] and (010)[001]. The (010)[001] slip system in clinopyroxene is newly found in this work. Melt was found at temperature of 950 °C-1050 °C. The melt glass distributed both in melt thin film between two grain boundaries and melt tubules of triangular along three grain boundaries at temperature of 950 °C-1000 °C. The melt triangular interconnected to the melt film at temperature of 1050 °C-1150 °C, where the melt chemical composition differentiated into iron-rich dark dots and silicate-rich matrix.
Juang, Titania; Das, Shiva; Adamovics, John; Benning, Ron; Oldham, Mark
2013-01-01
Purpose Deformable image registration (DIR) algorithms may enable multi-fraction dose tracking and improved treatment response assessment, but the accuracy of these methods must be investigated. This study introduces and evaluates a novel deformable 3D dosimetry system (Presage-Def/Optical-CT) and its application toward investigating the accuracy of dose deformation in a commercial DIR package. Methods and Materials Presage-Def is a new dosimetry material consisting of an elastic polyurethane matrix doped with radiochromic leuco dye. Radiological and mechanical properties were characterized using standard techniques. Dose-tracking feasibility was evaluated by comparing dose distributions between dosimeters irradiated with and without 27% lateral compression. A checkerboard plan of 5 mm square fields enabled precise measurement of true deformation using 3D dosimetry. Predicted deformation was determined from a commercial DIR algorithm. Results Presage-Def exhibited a linear dose response with sensitivity of 0.0032 ?OD/(Gy·cm). Mass density is 1.02 g/cm3 and effective atomic number is within 1.5% of water over a broad (0.03–10 MeV) energy range, indicating good water-equivalence. Elastic characteristics were close to liver tissue, with Young’s modulus of 13.5–887 kPa over a stress range of 0.233–303 kPa, and Poisson’s ratio of 0.475 (SE=0.036). The Presage-Def/Optical-CT system successfully imaged the non-deformed and deformed dose distributions with isotropic resolution of 1 mm. Comparison with the predicted deformed 3D dose distribution identified inaccuracies in the commercial DIR algorithm. While external contours were accurately deformed (sub-millimeter accuracy), volumetric dose deformation was poor. Checkerboard field positioning and dimension errors of up to 9 and 14 mm respectively were identified, and the 3D DIR-deformed dose gamma passing rate was only ?3%/3mm=60.0%. Conclusions The Presage-Def/Optical-CT system shows strong potential for comprehensive investigation of DIR algorithm accuracy. Substantial errors in a commercial DIR were found in the conditions evaluated. This work highlights the critical importance of careful validation of DIR algorithms prior to clinical implementation. PMID:23886417
Time-resolved biofilm deformation measurements using optical coherence tomography.
Blauert, Florian; Horn, Harald; Wagner, Michael
2015-09-01
The interaction of shear stress with the biofilm leads to a dynamic deformation, which is related to the structural and material characteristics of biofilms. We show how optical coherence tomography can be used as an imaging technique to investigate the time-resolved deformation on the biofilm mesoscale as well as to estimate mechanical properties of the biofilm. For the first time time-resolved deformation from cross-sectional views of the inner biofilm structure could be shown. Changes in the biofilm structure and rheological properties were calculated from cross sections in real-time and time-lapsed measurements. Heterotrophic biofilms were grown in a flow cell set-up at low shear stress of ?w? =?0.01?Pa. By applying higher shear stress elastic and viscoelastic behavior of biofilms were quantified. Deformation led to a change in biofilm conformation and allowed to estimate rheological properties. Assuming an ideal wall shear stress calculation, the shear modulus G?=?29.7?±?1.7?Pa and the Young's modulus E?=?36.0?±?2.6?Pa were estimated. PMID:25786671
International Nuclear Information System (INIS)
A study is made into ultrasonic impact surface treatment effect on the nature of plastic deformation and mechanical properties of loaded specimens of polycrystalline titanium VT1-0 and low carbon steel St. 3. Using light, transmission electron, scanning electron and scanning tunnel microscopies it is shown that ultrafine-grained structure resulting in a material surface layer ultrasonic treatment induces localization of plastic flow at various scale levels. The fine structure and the nature of propagation of meso- and macrobands of localized plastic deformation are investigated. It is established that mechanical properties of materials studied are dependent on the nature of propagation of meso- and macrobands of localized deformation
Analysis of Mining Terrain Deformation Characteristics with Deformation Information System
Blachowski, Jan; Milczarek, Wojciech; Grzempowski, Piotr
2014-05-01
Mapping and prediction of mining related deformations of the earth surface is an important measure for minimising threat to surface infrastructure, human population, the environment and safety of the mining operation itself arising from underground extraction of useful minerals. The number of methods and techniques used for monitoring and analysis of mining terrain deformations is wide and increasing with the development of geographical information technologies. These include for example: terrestrial geodetic measurements, global positioning systems, remote sensing, spatial interpolation, finite element method modelling, GIS based modelling, geological modelling, empirical modelling using the Knothe theory, artificial neural networks, fuzzy logic calculations and other. The aim of this paper is to introduce the concept of an integrated Deformation Information System (DIS) developed in geographic information systems environment for analysis and modelling of various spatial data related to mining activity and demonstrate its applications for mapping and visualising, as well as identifying possible mining terrain deformation areas with various spatial modelling methods. The DIS concept is based on connected modules that include: the spatial database - the core of the system, the spatial data collection module formed by: terrestrial, satellite and remote sensing measurements of the ground changes, the spatial data mining module for data discovery and extraction, the geological modelling module, the spatial data modeling module with data processing algorithms for spatio-temporal analysis and mapping of mining deformations and their characteristics (e.g. deformation parameters: tilt, curvature and horizontal strain), the multivariate spatial data classification module and the visualization module allowing two-dimensional interactive and static mapping and three-dimensional visualizations of mining ground characteristics. The Systems's functionality has been presented on the case study of a coal mining region in SW Poland where it has been applied to study characteristics and map mining induced ground deformations in a city in the last two decades of underground coal extraction and in the first decade after the end of mining. The mining subsidence area and its deformation parameters (tilt and curvature) have been calculated and the latter classified and mapped according to the Polish regulations. In addition possible areas of ground deformation have been indicated based on multivariate spatial data analysis of geological and mining operation characteristics with the geographically weighted regression method.
DEFF Research Database (Denmark)
Ramsgaard Thomsen, Mette; Tamke, Martin; Deleuran, Anders Holden
2011-01-01
Recent advancements towards performance based material system characteristics as key drivers of design are currently challenging the role of representation and prototyping in architectural research and practice. This paper shares findings from a research project exploring the potential of a hybrid digital-material prototype capable of alleviating this challenge. The project aims to explore the possibility of incorporating material properties into digital models using respectively analytical and ...
Highly Deformable Graphene Kirigami
Qi, Zenan; Park, Harold S; Campbell, David K.
2014-01-01
Graphene's exceptional mechanical properties, including its highest-known stiffness (1 TPa) and strength (100 GPa) have been exploited for various structural applications. However, graphene is also known to be quite brittle, with experimentally-measured tensile fracture strains that do not exceed a few percent. In this work, we introduce the notion of graphene kirigami, where concepts that have been used almost exclusively for macroscale structures are applied to dramaticall...
Materials dependence of deformation texture development in various deformation modes
Energy Technology Data Exchange (ETDEWEB)
Stout, M.G.; Kallend, J.S.; Kocks, U.F.; Przystupa, M.A.; Rollett, A.D.
1987-01-01
Attempts to understand the development of deformation textures have long been hampered by the following dichotomy: in theory, one expects orientation changes to be governed entirely by the geometry of deformation and thus to be the same for all materials of the same lattice structure and the same deformation modes; yet in experiments, one observes differences between different materials of the same lattice structure. The current work represents an effort to address this problem anew. Four fcc single-phase materials (aluminium, copper, silver, and 70:30 brass) were deformed along three strain-paths (wire-drawing, compression, and torsion), with complete texture determinations before deformation and after strains of roughly 1.0 and 2.0. In parallel, 800 randomly oriented but weighted grains were subjected to simulation of these same tests by the Los Alamos polycrystal plasticity (LApp) code, taking account of the initial textures. An ancillary question which could be addressed in this way is how long initial textures can be remembered by the material; the answer depends on the circumstances and is not always small strains. 8 refs., 3 figs., 1 tab.
Galois deformation theory for norm fields and flat deformation rings
Kim, Wansu
2010-01-01
Let $K$ be a finite extension of $\\mathbb{Q}_p$, and choose a uniformizer $\\pi\\in K$, and put $K_\\infty:=K(\\sqrt[p^\\infty]{\\pi})$. We introduce a new technique using restriction to $\\Gal(\\ol K/K_\\infty)$ to study flat deformation rings. We show the existence of deformation rings for $\\Gal(\\ol K/K_\\infty)$-representations ``of height $\\leqslant h$'' for any positive integer $h$, and we use them to give a variant of Kisin's proof of connected component analysis of a certain flat deformation rings, which was used to prove Kisin's modularity lifting theorem for potentially Barsotti-Tate representations. Our proof does not use the classification of finite flat group schemes, so it avoids Zink's theory of windows and displays when $p=2$. This $\\Gal(\\ol K/K_\\infty)$-deformation theory has a good analogue in positive characteristics analogue of crystalline representations in the sense of Genestier-Lafforgue. In particular, we obtain a positive characteristic analogue of crystalline deformation rings, and can analyze ...
Preferred orientation in experimentally deformed stishovite: implications for deformation mechanisms
Kaercher, P. M.; Zepeda-Alarcon, E.; Prakapenka, V.; Kanitpanyacharoen, W.; Smith, J.; Sinogeikin, S. V.; Wenk, H. R.
2014-12-01
The crystal structure of the high pressure SiO2 polymorph stishovite has been studied in detail, yet little is known about its deformation mechanisms. Information about how stishovite deforms under stress is important for understanding subduction of quartz-bearing crustal rocks into the mantle. Particularly, stishovite is elastically anisotropic and thus development of crystallographic preferred orientation (CPO) during deformation may contribute to seismic anomalies in the mantle. We converted a natural sample of flint to stishovite in a laser heated diamond anvil cell and compressed the stishovite aggregate up to 38 GPa. Diffraction patterns were collected in situ in radial geometry at the Advanced Light Source (ALS) and the Advanced Photon Source (APS) to examine development of CPO during deformation. We find that (001) poles preferentially align with the compression direction and infer deformation mechanisms leading to the observed CPO with visco-plastic self consistent (VPSC) polycrystal plasticity models. Our results show pyramidal and basal slip are most likely active at high pressure and ambient temperature, in agreement with transmission electron microscopy (TEM) studies of rutile (TiO2) and paratellurite (TeO2), which are isostructural to stishovite. Conversely other TEM studies of stishovite done at higher temperature suggest dominant prismatic slip. This indicates that a variety of slip systems may be active in stishovite, depending on conditions. As a result, stishovite's contribution to the seismic signature in the mantle may vary as a function of pressure and temperature and thus depth.
Residual deformations in ocular tissues.
Wang, Ruoya; Raykin, Julia; Gleason, Rudolph L; Ethier, C Ross
2015-04-01
Residual deformations strongly influence the local biomechanical environment in a number of connective tissues. The sclera is known to be biomechanically important in healthy and diseased eyes, such as in glaucoma. Here, we study the residual deformations of the sclera, as well as the adjacent choroid and retina. Using freshly harvested porcine eyes, we developed two approaches of quantifying residual deformations in the spherically shaped tissues of interest. The first consisted of punching discs from the posterior wall of the eye and quantifying the changes in the area and eccentricity of these samples. The second consisted of cutting a ring from the equatorial sclera and making stress-relieving cuts in it. Measurements of curvature were made before and after the stress-relieving cuts. Using the first approach, we observed a 42% areal contraction of the choroid, but only modest contractions of the sclera and retina. The observed contractions were asymmetric. In the second approach, we observed an opening of the scleral rings (approx. 10% decrease in curvature). We conclude that residual bending deformations are present in the sclera, which we speculate may be due to radially heterogeneous growth and remodelling of the tissue during normal development. Further, residual areal deformations present in the choroid may be due to the network of elastic fibres in this tissue and residual deformations in the constituent vascular bed. Future studies of ocular biomechanics should attempt to include effects of these residual deformations into mechanical models in order to gain a better understanding of the biomechanics of the ocular wall. PMID:25740853