Microscopic study of octupole-deformations in even-even 226-230Th isotopes
International Nuclear Information System (INIS)
Study of octupole correlations in the actinides has attracted interest because of the predictions that octupole deformation would be present in the Z ? 88 and N ?134 region. These predictions have been explored through a series of experimental studies, which have centred on energy spectra and transition properties. In the present work, the octupole-octupole interaction is incorporated to the pairing plus quadrupole-quadrupole model. The microscopic Cranked Hartree Bogoliubov framework (CHB) is employed with pairing plus quadrupole-quadrupole plus octupole-octupole interaction to study the non-axial nature of 226-230Th.
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
% IS322 \\\\ \\\\ 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.
Bonatsos, Dennis; Minkov, N; Karampagia, S; Petrellis, D
2015-01-01
The analytic quadrupole octupole axially symmetric model, which had successfully predicted 226Ra and 226Th as lying at the border between the regions of octupole deformation and octupole vibrations in the light actinides using an infinite well potential (AQOA-IW), is made applicable to a wider region of nuclei exhibiting octupole deformation, through the use of a Davidson potential (AQOA-D). Analytic expressions for energy spectra and B(E1), B(E2), B(E3) transition rates are derived. The spectra of 222-226Ra and 224,226Th are described in terms of the two parameters phi_0 (expressing the relative amount of octupole vs. quadrupole deformation) and beta_0 (the position of the minimum of the Davidson potential), while the recently determined B(EL) transition rates of 224Ra, presenting stable octupole deformation, are successfully reproduced. A procedure for gradually determining the parameters appearing in the B(EL) transitions from a minimum set of data, thus increasing the predictive power of the model, is out...
The multiphonon method as a dynamical approach to octupole correlations in deformed nuclei
International Nuclear Information System (INIS)
The octupole correlations in nuclei are studied within the framework of the multiphonon method which is mainly the exact diagonalization of the total Hamiltonian in the space spanned by collective phonons. This treatment takes properly into account the Pauli principle. It is a microscopic approach based on a reflection symmetry of the potential. The spectroscopic properties of double even and odd-mass nuclei are nicely reproduced. The multiphonon method appears as a dynamical approach to octupole correlations in nuclei which can be compared to other models based on stable octupole deformation. 66 refs
Experimental tests for stable octupole deformation in actinium-227
International Nuclear Information System (INIS)
The question of intrinsic reflection asymmetry or stable-octupole deformation in 227Ac was studied by the single-proton stripping reactions 226Ra(3He,d)227Ac with E/sub 3He/ = 30 MeV and 226Ra(?,t)227Ac with E/sub ?/ = 30 MeV and by measuring the magnetic moment of the first excited 3/2+ state at 27.38 keV by a differential perturbed angular correlation (DPAC) experiment. Theoretical differential cross sections were determined using calculated nuclear structure factors with and without octupole-deformed Woods-Saxon model wave functions. Theoretical values for the magnetic moments of the ground state and first excited state with and without octupole deformation were determined using calculated intrinsic g-factors from folded Yukawa model wave functions. The results of the proton-stripping cross sections are inconclusive. No how comparison of the measured values for the magnetic moment of the first excited state with a previous measurement for the ground state seems to support stable octupole deformation in 227Ac. Therefore, the energy ordering of orbitals and the magnetic moment results are consistent and they seem to support a stable-octupole deformed shape for the ground state parity doublet in 227Ac. Furthermore, the results are consistent with the branching ratio determination of the magnetic moment of the first excited state in 227Ac which is in agreement with the stable-octupole model prediction
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. \\...
Fast nuclear rotation and octupole deformation
Urban, W; Nyberg, J
2001-01-01
The 150Sm nucleus has been studied to high spins in a measurement of gamma radiation following the 136Xe(18O,4n)150Sm, compound-nucleus reaction at beam energy of 76 MeV. The measurement was performed at NBI Riso using the NORDBALL array. Alternating parity, s=+1 band in 150Sm has been observed up to spin I=22. This band is crossed by two aligned bands, corresponding to a reflection-symmetric shape. After the second crossing the s=+1 band ends abruptly, suggesting that the octupole shape vanishes in 150Sm above spin I=22, as predicted by calculations. Other explanations, assuming continuation of the s=+1 band past the two alignments are also discussed.
Bonatsos, Dennis; Martinou, Andriana; Minkov, N.; Karampagia, S.; Petrellis, D.
2015-05-01
The analytic quadrupole octupole axially symmetric model, which had successfully predicted 226Ra and 226Th as lying at the border between the regions of octupole deformation and octupole vibrations in the light actinides using an infinite well potential (AQOA-IW), is made applicable to a wider region of nuclei exhibiting octupole deformation, through the use of a Davidson potential, ?2+?04/?2 (AQOA-D). Analytic expressions for energy spectra and B (E 1 ),B (E 2 ),B (E 3 ) transition rates are derived. The spectra of Ra-226222 and Th,226224 are described in terms of the two parameters ?0 (expressing the relative amount of octupole vs quadrupole deformation) and ?0 (the position of the minimum of the Davidson potential), while the recently determined B (E L ) transition rates of 224Ra, presenting stable octupole deformation, are successfully reproduced. A procedure for gradually determining the parameters appearing in the B (E L ) transitions from a minimum set of data, thus increasing the predictive power of the model, is outlined.
Nuclear fusion as a probe for octupole deformation in $^{224}$Ra
Kumar, Raj; Vitturi, A
2015-01-01
$\\textit{Background}$: Nuclear fusion has been shown to be a perfect 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 stactic octupole deformation in nuclei will enhanced a possible permanent electric dipole moment, leading to a possible demonstration of parity violation. $\\textit{Purpose}$: To check whether static octupole deformation or octupole vibration in fusion give qualitatively different results so that both situations can be experimentally disentangled. $\\textit{Method}$: Fusion cross sections are computed in the Coupled-Channels formalism making use of the Ingoing-Wave Boundary Conditions (IWBC) for the systems $^{16}$O+$^{144}$Ba and $^{16}$O+$^{224}$Ra. $\\textit{Results}$: Barrier distributions of the two considered schemes show different patterns. For the $^{224}$Ra case, the octupole deformation parameter is large enough to create a sizeable difference. $\\textit{Con...
Self-consistent calculation of the quadrupole-octupole deformation energy surface of 222Ra
International Nuclear Information System (INIS)
The Hartree-Fock + BCS quadrupole-octupole deformation energy surface of 223Ra, calculated with the Skyrme SIII interaction, presents a minimum for a non-zero value of the octupole moment. Our results suggest the existence of a quadrupole coupling which may account for the observed differences between the moments of inertia of the positive- and negative-parity bands. (orig.)
Microscopic and semi-classical treatments of octupole deformation in the light actinides
International Nuclear Information System (INIS)
Microscopic and semi-classical descriptions of octupole deformation are compared. New semi-classical results, obtained with the use of a Woods-Saxon potential are presented. Comparisons with experiment are made. 21 references
Effect of the coriolis and centrifugal forces for nuclei with a stable octupole deformation
International Nuclear Information System (INIS)
Effects of the Coriolis and centrifugal forces for nuclei with a stable octupole deformation are examined in the frame of a schematic collective model. It is found that these effects are by no means attenuated with a rise of the octupole deformation. Taking them into account seems to allow for a consistent description of a strong anharmonization and differences in the moments of inertia of the positive- and negative-parity bands. (orig.)
Energy displacement function as a signature for octupole deformation in excited states
Raduta, A A; Ursu, I I
2003-01-01
Energies for three positive and three negative parity bands predicted by the extended coherent states model (ECSM) in sup 2 sup 2 sup 6 Ra are calculated and used to point out new signatures for octupole deformation in ground as well as in beta and gamma bands. A beat pattern is found by using a new displacement energy function which is more appropriate for a spectrum which exhibits large deviation from a linear J(J+1) dependence. The stability against octupole deformation is revisited from a new point of view. (authors)
Mechanism of chaos induced by the periodic driving octupole deformation
International Nuclear Information System (INIS)
The eigen values of the linear equations near the reference solutions of Hamiltonian-canonical equation are given by autonomy the time factor. It is demonstrated that the periodic time factor in octupole potential provides the particle to have more opportunity to encounter the negative curvature of the potential surface. Therefore the particle will be easier to get chaos, according to the discrimination of the motions for regulation and chaos. (authors)
About collective states of even-even nuclei with quadrupole and octupole deformations
International Nuclear Information System (INIS)
The simple analytical expressions for energy levels, reduced probabilities E2-transitions inside levels of positive and negative parities, E1-transitions between contrary parities of deformable axial-symmetrical. even-even nuclei with ?2 quadrupole and ?3 octupole deformations for potential energy of surface vibrations v =(V0/?2)(?-?0)2 are obtained. Here ?2= (B2?22/(B2+B3))+(B3?32/(B2+B3) and B2 , B3 - mass parameters for quadrupole and octupole deformations, V0 and ?0 - parameters of potential energy. The ratio energy levels with positive parities of ground bands are determined by parameters ??+, and with negative parities of octupole bands are determined by two parameters ??+ and ??-, where always ??+ ?-. The reduced probabilities E2-transitions also are determined by parameters ??+ or ??-, and El-transitions are determined by two parameters ??+, ??-, also El-transitions direct proportional to polarization electric dipole moment (PEDM) D0 and inversely proportional to inside quadrupole moment Q00. At theoretical calculations of the energy levels quantum number of vibrations not integer number, but is a decision of the transcendental equation. At calculations of the reduced probabilities of E2 and E1-transitions is-an integer number. These calculations shows, which this theoretical model satisfactorily describes of the energy levels, reduced probabilities of E2 and El-transitions of deformable axial-symmetries even-even nuclei, including high spin states.
Influence of angular momentum in axially symmetric potentials with octupole deformation
International Nuclear Information System (INIS)
The chaotic classical single-particle motion in an oblate octupole deformed potential with a non-zero z-component of angular momentum Lz is investigated. The stability analysis of the trajectories shows that with increasing rotation of the system, the unstable negative curvature regions of the effective potential surface decrease, which converts the chaotic motion of the system into a regular one. (authors)
Competition between axial and non-axial octupole deformations in heavy nuclei
International Nuclear Information System (INIS)
The macroscopic-microscopic method is applied to calculate the energies of heavy nuclei (A>220) in a multidimensional deformation space (??,?) including axial and non-axial quadrupole (?=2,?=0,2), axial and non-axial octupole (?=3,?=0,2) and axial hexadecapole (?=4,?=0) degrees of freedom. Shell and pairing corrections are calculated from the single-particle energies of the Woods-Saxon potential with the universal parameters and added to the macroscopic energy of the newest Lublin-Strasbourg Drop (LSD) model to obtain the total deformation energy. (author)
Accuracy of the multipole expansion of density distribution in the presence of octupole deformation
International Nuclear Information System (INIS)
The accuracy of multipole expansion of density distribution for deformed nuclei is tested. The interaction potential for a deformed-spherical pair of nuclei was calculated using the folding model derived from zero-range nucleon–nucleon (NN) interaction. We considered two spherical projectiles Ca40 and Pb208 scattered on U238 deformed target nucleus. The error in the heavy ion (HI) potential resulting from using a truncated multipole density expansion is evaluated for each case in the presence of octupole deformation ?3 besides quadrupole ?2. We are interested in the value of error for R ? RT (touching distance). We found that for values of |?3|?0.1 the error at R = RT reaches reasonable values when six terms expansion is used. For |?3| = 0.2, we calculated the Coulomb barrier parameters using realistic NN force and found that the large error present in six terms for zero range force decreases strongly to less than 1% when the zero range is added to finite range forces and Coulomb interaction to form the Coulomb barrier. It is noted that the negative value of octupole deformation parameters ?3 = -0.1 produce error at orientation angle ? equal in value to that produced at angle (180°-?) for the positive values ?3 = 0.1. We also found that the error decreases as the mass number of the projectile nucleus increases. (author)
Measurements of multipolarities in 227Ra as tests of evidence for stable octupole deformation
International Nuclear Information System (INIS)
Multipolarities of ?30 transitions in 227Ra have been established by measuring conversion electrons following the ?- decay of 227Fr. For this purpose a 'mini-orange'-type electron spectrometer has been constructed. The 227Fr isotopes were produced by the ISOLDE on-line separator at the CERN Synchro-cyclotron. Internal conversion coefficients were obtained from singles spectra and also from simultaneous ?e- and ?? coincidence measurements. The new results support the placement of levels and transitions in the earlier level scheme but require changes in the previously assigned parities for four of the levels. Also, one E0 transition was identified. The results are consistent with previous interpretations for most of the levels that have been used to argue in favour of a small permanent octupole deformation for 227Ra. (orig.)
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.
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
Octupole correlations in the heavy elements
International Nuclear Information System (INIS)
The effects of octupole correlations on the nuclear structure of the heavy elements are discussed. The cluster model description of the heavy elements is analyzed. The relevance of 26-pole deformation and fast El transitions to an octupole model is considered. 30 refs., 21 figs., 1 tab
Microscopic analysis of the octupole phase transition in Th isotopes
Nomura, K; Lu, B -N
2013-01-01
A shape phase transition between stable octupole deformation and octupole vibrations in Th nuclei is analyzed in a microscopic framework based on nuclear density functional theory. The relativistic functional DD-PC1 is used to calculate axially-symmetric quadrupole-octupole constrained energy surfaces. Observables related to order parameters are computed using an interacting-boson Hamiltonian, with parameters determined by mapping the microscopic energy surfaces to the expectation value of the Hamiltonian in the boson condensate. The systematics of constrained energy surfaces and low-energy excitation spectra point to the occurrence of a phase transition between octupole-deformed shapes and shapes characterized by octupole-soft potentials.
Simultaneous quadrupole and octupole shape phase transitions in Thorium
Li, Z. P.; Song, B. Y.; Yao, J. M.; Vretenar, D.; Meng, J.
2013-01-01
The evolution of quadrupole and octupole shapes in Th isotopes is studied in the framework of nuclear Density Functional Theory. Constrained 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 neutron number. The nucleus $^{224}$Th is closest to...
Time invariance violating nuclear electric octupole moments
Flambaum, V V; Orton, S R
1997-01-01
The existence of a nuclear electric octupole moment (EOM) requires both parity and time invariance violation. The EOMs of odd $Z$ nuclei that are induced by a particular T- and P-odd interaction are calculated. We compare such octupole moments with the collective EOMs that can occur in nuclei having a static octupole deformation. A nuclear EOM can induce a parity and time invariance violating atomic electric dipole moment, and the magnitude of this effect is calculated. The contribution of a nuclear EOM to such a dipole moment is found, in most cases, to be smaller than that of other mechanisms of atomic electric dipole moment production.
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
Giant Octupole Resonance Simulation
Walke, Rainer; Morawetz, Klaus
1998-01-01
Using a pseudo-particle technique we simulate large-amplitude isoscalar giant octupole excitations in a finite nuclear system. Dependent on the initial conditions we observe either clear octupole modes or over-damped octupole modes which decay immediately into quadrupole ones. This shows clearly a behavior beyond linear response. We propose that octupole modes might be observed in central collisions of heavy ions.
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
Non-axial Octupole Deformations of $N=Z$ Nuclei in $A \\sim 60-80$ Mass Region
Matsuo, M; Yabana, K
1998-01-01
By performing a fully three dimensional Hartree-Fock calculation with use of the Skyrm forces, we demonstrate possibility of exotic deformations violating both the reflection and the axial symmetries of N=Z nuclei in $A \\sim 60-80$ mass region. The \\Ytwo tetrahedral shape predicted in excited \\Zr arises from a shell gap at $N,Z = 40$ which is enhanced for the tetrahedron deformation. Softness toward the \\Ythree triangular deformation of the oblate state in \\Se is also predicted.
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.
Simultaneous quadrupole and octupole shape phase transitions in Thorium
Energy Technology Data Exchange (ETDEWEB)
Li, Z.P.; Song, B.Y.; Yao, J.M. [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China); Vretenar, D. [Physics Department, Faculty of Science, University of Zagreb, 10000 Zagreb (Croatia); Kavli Institute for Theoretical Physics China, CAS, Beijing 100190 (China); Meng, J., E-mail: mengj@pku.edu.cn [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China); Department of Physics, University of Stellenbosch, Stellenbosch (South Africa)
2013-11-04
The evolution of quadrupole and octupole shapes in Th isotopes is studied in the framework of nuclear Density Functional Theory. Constrained 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 neutron number. The nucleus {sup 224}Th is closest to the critical point of a double phase transition. A microscopic mechanism of this phenomenon is discussed in terms of the evolution of single-nucleon orbitals with deformation.
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
Buchmann, A. J.; Henley, E. M.
2008-01-01
We report on a calculation of higher electromagnetic multipole moments of baryons in a non-covariant quark model approach. The employed method is based on the underlying spin-flavor symmetry of the strong interaction and its breaking.We present results on magnetic octupole moments of decuplet baryons and discuss their implications.
Global systematics of octupole excitations in even-even nuclei
International Nuclear Information System (INIS)
We present a computational methodology for a theory of the lowest axially symmetric octupole excitations applicable to all even-even nuclei beyond the lightest. The theory is the well-known generator-coordinate extension (GCM) of the Hartree-Fock-Bogoliubov (HFB) self-consistent mean field theory. We use the discrete-basis Hill-Wheeler (HW) method to compute the wave functions with an interaction from the Gogny family of Hamiltonians. Comparing to the compiled experimental data on octupole excitations, we find that the performance of the theory depends on the deformation characteristics of the nucleus. For nondeformed nuclei, the theory reproduces the energies to about ±20% apart from an overall scale factor of ?1.6. The performance is somewhat poorer for (quadrupole) deformed nuclei, and for both together the dispersion of the scaled energies about the experimental values is about ±25%. This compares favorably with the performance of similar theories of the quadrupole excitations. Nuclei having static octupole deformations in HFB theory form a special category. These nuclei have the smallest measured octupole excitation energies as well as the smallest predicted energies. However, in these cases the energies are seriously underpredicted by the theory. We find that a simple two-configuration approximation, the minimization after projection (MAP) method, is almost as accurate as the full HW treatment, provided that the octupole-deformed nuclei are omitted from the -deformed nuclei are omitted from the comparison. This article is accompanied by a tabulation of the predicted octupole excitations for 818 nuclei extending from drip-line to drip-line, computed with several variants of the Gogny interaction.
Chromaticity dependence on octupole strength
Herr, W; Metral, E; Mounet, N; Papotti, G; Tomas Garcia, R; Wenninger, J
2012-01-01
The first measurements of the dependence of the chromaticity on the lattice octupole strength were performed at the LHC in a machine development session on Wednesday 20 June 2012. This chromaticity change is non negligible and needs to be taken into account when changing the octupole strength, e.g. for beam stabilization purposes. We report on the results of such measurements and later ones, along with some predictions and some first estimates of systematic horizontal and vertical misalignments of the octupoles.
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.
Octupole correlation effects in nuclei
International Nuclear Information System (INIS)
Octupole correlation effects in nuclei are discussed from the point of view of many-body wavefunctions as well as mean-field methods. The light actinides, where octupole effects are largest, are considered in detail. Comparisons of theory and experiment are made for energy splittings of parity doublets; E1 transition matrix elements and one-nucleon transfer reactions
Non-yrast quadrupole-octupole spectra
Directory of Open Access Journals (Sweden)
Lenske H.
2012-12-01
Full Text Available A model of strongly coupled quadrupole and octupole vibrations and rotations is applied to describe non-yrast alternating-parity sequences in even-even nuclei and split parity-doublet spectra in odd-mass nuclei. In even-even nuclei the yrast alternating-parity sequence includes the ground-state band and the lowest negative-parity levels with odd angular momenta, while the non-yrast sequences include excited ?-bands and higher negative-parity levels. In odd-mass nuclei the yrast levels are described as low-energy rotation-vibration modes coupled to the ground single-particle (s.p. state, while the non-yrast parity-doublets are obtained as higher-energy rotation-vibration modes coupled to excited s.p. configurations. We show that the extended model scheme describes the yrast and non-yrast quadrupole-octupole spectra in both even-even and odd-A nuclei. The involvement of the reflection-asymmetric deformed shell model to explain the single-particle motion and the Coriolis interaction in odd nuclei is discussed.
Stable and Vibrational Octupole Modes in Mo, Xe, Ba, La, Ce and Nd
International Nuclear Information System (INIS)
Evidence is presented for stable octupole deformation in neutron-rich nuclei, bounded by Z = 54-58 and N = 85-92. To either side of this region negative parity bands built on more vibrational type octupole modes are observed in 140Ba and 152,154Nd. The largest stable octupole deformation (?s ? 0.1) is found in 144Baas. The theoretically predicted quenching (?s ? 0) of stable octupole deformation at higher spins is found in 140Ba. There is good agreement between theory and experiment for the strongly varying electric dipole moments as a function of mass for 142-141Ba. In odd-A 142Ba and odd-Z 140La, we observe parity doublets, two pairs of positive and negative parity bands with opposite spins. In 145La a strong coupled ground band with symmetric shape coexists with the asymmetric octupole shape which stabilizes above about spin 19/2. In 145,147La a strong reduction in E2 strength around 25/2 from band crossing is observed. The isotope 109Mo was identified and a new region of stable uctpole deformation is identified in 107,108Mo centered around N = 64-66 as earlier predicted. This is the first case of stable uctpole deformation involving only one pair of orbitals
Global systematics of octupole excitations in even-even nuclei
Robledo, L M
2011-01-01
We present a computational methodology for a theory of the lowest octupole excitations applicable to all even-even nuclei beyond the lightest. The theory is the well-known generator-coordinate extension (GCM) of the Hartree-Fock-Bogoliubov self-consistent mean field theory (HFB). We use the discrete-basis Hill-Wheel method (HW) to compute the wave functions with an interaction from the Gogny family of Hamiltonians. Comparing to the compiled experimental data on octupole excitations, we find that the performance of the theory depends on the deformation characteristics of the nucleus. For nondeformed nuclei, the theory reproduces the energies to about 20 % apart from an overall scale factor of about 1.6. The performance is somewhat poorer for (quadrupole) deformed nuclei, and for both together the dispersion of the scaled energies about the experimental values is about 25 %. This compares favorably with the performance of similar theories of the quadrupole excitations. Nuclei having static octupole deformations...
Investigation of micro de-formative properties of irradiated polymers
International Nuclear Information System (INIS)
Using the methods of X-ray investigation and mechanical load of samples we investigated micro de-formative properties of irradiated polymers. We showed that with increase of irradiation dose of linking polymers all types of heterogeneous micro de-formation and slipping gradually suppress and, finally, we see homogeneous micro de-formation of the system
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.
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...
Structure and properties of copper deformed by severe plastic deformation methods
Directory of Open Access Journals (Sweden)
M. Richert
2011-01-01
Full Text Available Purpose: The main object of this study is to establish the influence of severe plastic deformation on the microstructure evolution and properties of polycrystalline copper Cu99.99.Design/methodology/approach: Polycrystalline copper Cu99.99 was deformed by cyclic extrusion compression (CEC, equal channel angular pressing (ECAP and hydrostatic extrusion (HE. Additionally the combination of these methods were applying to the sample deformations. The microstructure and properties of samples after different kinds of severe mode of deformations (SPD were examined and compared as well as their properties. The microstructure was investigated by optical (MO and transmission electron microscopy (TEM. The microhardness was measured by PMT3 microhardness tester.Findings: It was found that increase of deformation diminishing the microstructure and leads to the increase of microhardness of samples.Practical implications: The results may be utilized for determination of a relation between microstructure and properties of the copper deformed in the severe plastic deformation process.Originality/value: The results contribute to evaluation properties of the polycrystalline copper deformed to very large strains exerting the typical range of deformations.
International Nuclear Information System (INIS)
The systematics of differences of levels of ground-state ?1 and ?1 bands in medium and heavy nuclei are shown to be smooth, even in cases in which the corresponding band heads show irregular behaviour. Deviations from these smooth systematics are shown to be signs of the presence of intruder bands, for which a new criterion is found. The systematics of differences of levels of octupole bands are used as parameter independent tests for the versions of the interacting boson model suitable for the description of octupole deformations as well as octupole vibrations. Examples of the usefulness of the present systematics in testing the predictions of various microscopic calculations are given. (author)
Deformation bands in porous sandstones, their microstructure and petrophysical properties
Torabi, Anita
2008-01-01
Deformation bands are commonly thin tabular zones of crushed or reorganized grains that form in highly porous rocks and sediments. Unlike a fault, typically the slip is negligible in deformation bands. In this dissertation the microstructure and petrophysical properties of deformation bands have been investigated through microscopy and numerical analysis of experimental and natural examples. The experimental work consists of a series of ring-shear experiments performed on porou...
Cluster (quadrupole-octupole) phonon model: Application to 89Y
International Nuclear Information System (INIS)
A cluster-phonon model is proposed for odd-mass nuclei to describe simultaneously positive- and negative-parity states, in which octupole as well as quadrupole vibrations of the core are allowed. The cluster states include one-particle and two-particle-one-hole excitations. The residual interaction is of the quadrupole-quadrupole plus pairing type. The model is applied to 89Y, whose energy levels, eigenvectors, spectroscopic factors, and electromagnetic properties are computed and compared with experiment
Nuclear collective motion with a coherent coupling interaction between quadrupole and octupole modes
Minkov, N; Drenska, S B; Scheid, W; Bonatsos, D; Lenis, D; Petrellis, D
2006-01-01
A collective Hamiltonian for the rotation-vibration motion of nuclei is considered, in which the axial quadrupole and octupole degrees of freedom are coupled through the centrifugal interaction. The potential of the system depends on the two deformation variables $\\beta_2$ and $\\beta_3$. The system is considered to oscillate between positive and negative $\\beta_3$-values, by rounding an infinite potential core in the $(\\beta_2,\\beta_3)$-plane with $\\beta_2>0$. By assuming a coherent contribution of the quadrupole and octupole oscillation modes in the collective motion, the energy spectrum is derived in an explicit analytic form, providing specific parity shift effects. On this basis several possible ways in the evolution of quadrupole-octupole collectivity are outlined. A particular application of the model to the energy levels and electric transition probabilities in alternating parity spectra of the nuclei $^{150}$Nd, $^{152}$Sm, $^{154}$Gd and $^{156}$Dy is presented.
Some properties of deformed q-numbers
Scientific Electronic Library Online (English)
Thierry C. Petit, Lobão; Pedro G. S., Cardoso; Suani T. R., Pinho; Ernesto P., Borges.
2009-08-01
Full Text Available Nonextensive statistical mechanics has been a source of investigation in mathematical structures such as deformed algebraic structures. In this work, we present some consequences of q-operations on the construction of q-numbers for all numerical sets. Based on such a construction, we present a new p [...] roduct that distributes over the q-sum. Finally, we present different patterns of q-Pascal's triangles, based on q-sum, whose elements are q-numbers.
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.
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.
Nanomechanical properties of poly(l-lactide) nanofibers after deformation.
Shao, Jundong; Wang, Yingjun; Chen, Xiaofeng; Hu, Xiaomeng; Du, Chang
2014-08-01
Atomic force microscopy (AFM) technique was used to investigate the nanomechanical properties of poly(l-lactide) (PLLA) nanofibers produced by the thermally induced phase separation (TIPS) method. Firstly, AFM-based nanolithography was employed to produce localized deformations on the surface of single PLLA nanofiber, in which the AFM tip served as a nanoscale burin to draw a scratch longitudinally along the nanofiber. Secondly, the morphology and physical properties of the nanofiber before and immediately after the deformation were characterized with AFM and force spectroscopy measurement. During the initial stage of TIPS process, the crystallization of PLLA resulted in a regular arrangement of crystalline domains along the thinner fibrils which then assembled laterally into larger nanofibers. The deformation due to the nanoindentation and plowing with the probe induced structural variation of PLLA nanofibers and led to a functional consequence in their nanomechanical properties. The region after deformation had a higher adhesion force and elastic modulus, probably because the polymer chains became more compact and ordered under both compression and shear stresses. PMID:24905683
Deformation bands in porous sandstones their microstructure and petrophysical properties
Energy Technology Data Exchange (ETDEWEB)
Torabi, Anita
2007-12-15
Deformation bands are commonly thin tabular zones of crushed or reorganized grains that form in highly porous rocks and sediments. Unlike a fault, typically the slip is negligible in deformation bands. In this dissertation the microstructure and petrophysical properties of deformation bands have been investigated through microscopy and numerical analysis of experimental and natural examples. The experimental work consists of a series of ring-shear experiments performed on porous sand at 5 and 20 MPa normal stresses and followed by microscopic examination of thin sections from the sheared samples. The results of the ring-shear experiments and comparison of them to natural deformation bands reveals that burial depth (level of normal stress in the experiments) and the amount of shear displacement during deformation are the two significant factors influencing the mode in which grains break and the type of shear zone that forms. Two end-member types of experimental shear zones were identified: (a) Shear zones with diffuse boundaries, which formed at low levels of normal stress and/or shear displacement; and (b) Shear zones with sharp boundaries, which formed at higher levels of normal stress and/or shear displacement. Our interpretation is that with increasing burial depth (approximately more than one kilometer, simulated in the experiments by higher levels of normal stress), the predominant mode of grain fracturing changes from flaking to splitting; which facilitates the formation of sharp-boundary shear zones. This change to grain splitting increases the power law dimension of the grain size distribution (D is about 1.5 in sharp boundary shear zones). Based on our observations, initial grain size has no influence in the deformation behavior of the sand at 5 MPa normal stresses. A new type of cataclastic deformation band is described through outcrop and microscopic studies; here termed a 'slipped deformation band'. Whereas previously reported cataclastic deformation bands are characterized by strain hardening, these new bands feature a central slip surface, which indicates late strain softening. They lack the characteristic compaction envelop, and are typified by higher porosity and lower permeability than previously-described cataclastic deformation bands. Intense background fracturing of the host rock and significant initial porosity are considered to be important in creating these newly-discovered deformation bands. In a related study, we investigate, for millimeter- wide deformation bands, the scale limitation inherent in laboratory measurements of porosity and permeability. The scale limitations imposed by the deformation band relative to the physical sample size motivated us to develop a new method for determining porosity and permeability based on image processing. While plug measurements measure the effective permeability across a 25.4 mm (1 inch) long sample, which includes both host rock and deformation band, the method presented here provides a means to estimate porosity and permeability of deformation band on microscale. This method utilizes low-order (one- and two orders) spatial correlation functions to analyze high-resolution, high-magnification backscatter images, to estimate the porosity and specific surface area of the pore-grain interface in the deformed sandstones. Further, this work demonstrates the use of a modified version of the Kozeny-Carmen relation to calculate permeability by using porosity and specific surface area obtained through the image processing. The result shows that permeability difference between the band and the host rock is up to four orders of magnitude. Moreover, the porosities and permeabilities estimated from image processing are lower than those obtained from their plug measurements; hence the traditional laboratory measurements have been overestimating permeability because of the previously-unrecognized scale problem. In addition, the image processing results clearly show that, as a result of microstructural variation, both porosity and permeability vary along the leng
Microscopic description of octupole shape-phase transitions in light actinides and rare-earth nuclei
Nomura, K; Niksic, T; Lu, Bing-Nan
2014-01-01
A systematic analysis of low-lying quadrupole and octupole collective states is presented, 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 condensate state, the Hamiltonian parameters are determined. The study is based on the global relativistic energy density functional DD-PC1. The resulting IBM Hamiltonian is used to calculate excitation spectra and transition rates for the positive- and negative-parity collective states in four isotopic chains characteristic for two regions of octupole deformation and collectivity: Th, Ra, Sm and Ba. Consistent with the empirical trend, the microscopic calculation based on the systematics of $\\beta_{2}$-$\\beta_{3}$ energy maps, the resulting low-lying negative-parity bands and transition rates show evidence of a shape transition be...
Radial damping by octupole for ZGS beam
International Nuclear Information System (INIS)
Landau damping by the octupolar tune spread is used to prevent the radial blowup of the beam during the acceleration cycle. The octupole field is produced by a set of pole face windings in the ring magnets. The strength of the octupole field, which is controlled by the Zero Gradient Synchrotron (ZGS) programmer, is set to give a tune profile of ?/sub x/ = 0.83 + 0.008 x a2, where a is the radial coordinate of the aperture in unit of cm. The radial damper feedback system, which has been operating for some years, has been replaced by this octupole, and the radial stability is remarkably improved by the new system
The electrochemical properties of the cyclic deformed passive metals
International Nuclear Information System (INIS)
It has been investigated the influence of chloride environment on corrosion fatigue fracture of different classes stainless steels. The change of electrochemical properties of deformed corrosion resistance steels and alloys during the initial stage of corrosion fatigue fracture has been studied. It has been determined the influence of micro-deformation processes of surface at different tensions on the electrochemical activating of stainless steels. The critical values of electrochemical parameters of the deformed metal has been established, at which probability of corrosion fatigue fracture grows sharply. The features of character change polarization current of stainless steels at loadings even to corrosion fatigue limit has been shown. It served by basis for development of method speed-up determination of corrosion fatigue limit without destruction of specimens. It has been established possibility of decline corrosion currents of stainless steels as a result of deformation at tensions which do not cause destruction. It was revealed the reason of this effect: different acceleration by mechanical tensions of dissolution of alloys separate components, that results in enrichment of surface by a chrome and nickel. It is instrumental in the improvement of protective properties of passive tapes. The analysis of results of the conducted researches allowed to set that corrosion endurance of stainless steels is determined by intensity of their electrochemical activating at tensions of even to corrosive fatigue limit. (authors)
Parametrization of the octupole degrees of freedom
Wexler, C
1999-01-01
A simple parametrization for the octupole collective variables is proposed and the symmetries of the wave functions are discussed in terms of the solutions corresponding to the vibrational limit. [PACS: 21.60Ev, 21.60.Fw, 21.10.Re
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.
Fission fragment properties at scission with the Gogny force
Energy Technology Data Exchange (ETDEWEB)
Dubray, N.; Goutte, H.; Berger, J.F.; Delaroche, J.P. [CEA Bruyeres-le-Chatel, 91 (France)
2008-07-01
Two-dimensional Hartree-Fock-Bogoliubov (HFB) calculations have been performed from spherical shapes to large deformations with constraints on axial quadrupole and octupole deformations in U-238, Fm-256-260 and Th-226 actinides. Scission configurations have then been identified in this subspace of collective coordinates and many nuclear properties of the nascent fragments have been derived, such as deformation, deformation energy or prompt neutron multiplicity. The HFB states have then served as basis states for time-dependent collective calculations based on the Time-Dependent Generator Coordinate Method and the Gaussian Overlap Approximation to derive fission fragment yields. (authors)
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.
Chiral symmetry restoration and pion properties in a q-deformed NJL model
Scientific Electronic Library Online (English)
V. S., Timóteo; C. L., Lima.
2006-03-01
Full Text Available We review the implementation of a q-deformed fermionic algebra in the Nambu-Jona-Lasinio model (NJL). The gap equations obtained from a deformed condensate as well as from the deformation of the NJL Hamiltonian are discussed. The effect of both temperature and deformation in the chiral symmetry rest [...] oration process as well as in the pion properties is studied.
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
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
Quadrupole and octupole correlations in normal, superdeformed and hyperdeformed states of 194Pb
International Nuclear Information System (INIS)
Quadrupole and octupole correlations in 194Pb are investigated by means of the generator coordinate method. Static microscopic wave functions are obtained by constrained Hartree-Fock+BCS calculations using the effective interaction SkM*. Quadrupole deformations from ground state to hyperdeformation region are included. Superdeformed band heads of both parities are predicted. The depopulation of the even superdeformed band is calculated. The odd-parity superdeformed band slowly decays to the ground even-parity superdeformed band over many E1 transitions. ((orig.))
Octupole focusing in transport and acceleration systems
International Nuclear Information System (INIS)
The radio-frequency quadrupole (RFQ) linac is capable of accelerating high-current, low-velocity ion beams. In accelerator systems comprising an RFQ and higher velocity accelerating structures, the current bottleneck still typically occurs within the RFQ. This limiting current is quite high in most cases, but linacs with even higher currents may be required in the future. We have begun a study of higher multipole systems to determine their capability for focusing and accelerating very high currents. We have chosen first to examine a radio-frequency octupole (RFO) transport system, and have developed a smooth-approximation analytical description that includes the conditions for input radial matching of a zero space-charge beam. Further, we have constructed a multiparticle beam-dynamics simulation program that accepts the low-current matched beam and gradually increases the beam current as it is transported. This results in a matched high-current beam, and the procedure can be used to determine the saturation-current limit of a periodic octupole system. As expected, at high currents the beam develops a hollow radial distribution that reduces the space-charge defocusing; initial results show that high currents can be transported. For acceleration, we have formulated the design parameters for a section of RFO linac, including the potential function, acceleration, and focusing efficiencies, and the geometry of the radially modulated pole tips
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...
High ? studies in the Wisconsin Toroidal OctupoleHigh ? studies in the Wisconsin Toroidal Octupole
International Nuclear Information System (INIS)
A wide range of MHD stable high ? plasmas is produced in the Wisconsin Levitated Octupole. At or near the single fluid regime we obtain, in the bad curvature region, ? = nk(T/sub e/ + T/sub i/)8?/B2 approx. = 8%, twice the theoretical single fluid ballooning instability limit of 4%. We also obtain stable plasmas at ? approx. = 35%, 9 times the theoretical limit, in a regime in which both finite ion gyroradius and gyroviscosity effects are importantA wide range of MHD stable high ? plasmas is produced in the Wisconsin Levitated Octupole. At or near the single fluid regime we obtain, in the bad curvature region, ? = nk(T/sub e/ + T/sub i/)8?/B2 approx. = 8%, twice the theoretical single fluid ballooning instability limit of 4%. We also obtain stable plasmas at ? approx. = 35%, 9 times the theoretical limit, in a regime in which both finite ion gyroradius and gyroviscosity effects are important
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.
Intrinsic structure effects in the octupole bands of 152Sm
International Nuclear Information System (INIS)
Collective octupole bands with Ksup(?) = 0-, 1- have been observed to high spin in 152Sm. The difference in their level spacings is interpreted to be a consequence of the contributing quasiparticle configuration. (orig.)
Deformation effect on properties and fine structure of invar
International Nuclear Information System (INIS)
Determined is deformation effect (with degrees of 10, 30, 50 %) before standard heat treatment (hardening from 830 deg C + tempering at 315 deg C + ageing at 95 deg C 48 hrs) on the temperature coefficient of linear expansion ?, coercive force, hardness and fine invar structure (the region of coherent scattering and microdistortions). It is found that the degree of deformation considerably affects Hsub(c), HV and substructural invar characteristics, the 10% reduction decreases ? in the course of standard heat treatment
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: 4.198, year: 2013
Dubray, N.; Goutte, H.; Delaroche, J.-P.
2007-01-01
The constrained Hartree-Fock-Bogoliubov method is used with the Gogny interaction D1S to calculate potential energy surfaces of fissioning nuclei ${}^{226}$Th and ${}^{256,258,260}$Fm up to very large deformations. The constraints employed are the mass quadrupole and octupole moments. In this subspace of collective coordinates, many scission configurations are identified ranging from symmetric to highly asymmetric fragmentations. Corresponding fragment properties at scission...
Dubray, N; Delaroche, J -P
2007-01-01
The constrained Hartree-Fock-Bogoliubov method is used with the Gogny interaction D1S to calculate potential energy surfaces of fissioning nuclei ${}^{226}$Th and ${}^{256,258,260}$Fm up to very large deformations. The constraints employed are the mass quadrupole and octupole moments. In this subspace of collective coordinates, many scission configurations are identified ranging from symmetric to highly asymmetric fragmentations. Corresponding fragment properties at scission are derived yielding fragment deformations, deformation energies, energy partitioning, neutron binding energies at scission, neutron multiplicities, charge polarization and total fragment kinetic energies.
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.
String field theory. Algebraic structure, deformation properties and superstrings
Energy Technology Data Exchange (ETDEWEB)
Muenster, Korbinian
2013-07-23
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.
Effect of deformation rate on the mechanical properties of arteries
Directory of Open Access Journals (Sweden)
Savvas G. Hatzikiriakos
2010-03-01
Full Text Available Pig aorta samples were tested uniaxially and equi- biaxially at deformation rates from 10 to 200 %/s. Under uniaxial and biaxial testing, loading forces were reduced up to 20% when the deformation rate was increased from 10 to 200 %/s, which is the opp- osite to the behaviour seen in other biological tissues. A rate-dependent isotropic hyperelastic constitutive equation, derived from the Mooney-Rivlin model, was fitted to the experimental results (e.g. aorta specimens using an inverse finite element technique. In the proposed model, one of the material par- ameters is a linear function of the deformation rate. The inverse relationship between stiffness and defo- rmation rate raises doubts on the hypothesized rel- ationship between intramural stress, arterial injury, and restenosis.
Mechanical properties of hot deformed Inconel 718 and X750
Directory of Open Access Journals (Sweden)
A. Nowotnik
2012-02-01
Full Text Available Purpose: Variations of a flow stress vs. true strain illustrate behavior of material during plastic deformation. Stress-strain relationship is generally evaluated by a torsion, compression and tensile tests.Design/methodology/approach: Compression tests were carried out on precipitations hardenable nickel based superalloys of Inconel 718 and X750 at constant true strain rates of 10-4, 4x10-4s-1 within temperature through which precipitation hardening phases process occurred (720-1150°C using thermomechanical simulator Gleeble and dilatometer Baehr 850D/L equipped with compression unit. True stress-true strain curves analysis of hot deformed alloys were described.Findings: On the basis of received flow stress values activation energy of a high-temperature deformation process was estimated. Mathematical dependences (?pl -T i ?pl - ? and compression data were used to determine material’s constants. These constants allow to derive a formula that describes the relationship between strain rate (?, deformation temperature (T and flow stress ?pl.Research limitations/implications: Study the flow stress will be continued on the samples after the aging process.Practical implications: The results of high-temperature deformation of the examined Inconel alloys may possibly find some practical use in the workshop practice to predict a flow stress values, but only within particular temperature and strain rate ranges. The results of the study can be used in the aerospace industry to produce blades for jet engines.Originality/value: The results of the study can be used in the aerospace industry to produce blades for jet engines.
International Nuclear Information System (INIS)
The constrained Hartree-Fock-Bogoliubov method is used with the Gogny interaction D1S to calculate potential energy surfaces of fissioning nuclei 226Th and 256,258,260Fm up to very large deformations. The constraints employed are the mass quadrupole and octupole moments. In this subspace of collective coordinates, many scission configurations are identified ranging from symmetric to highly asymmetric fragmentations. Corresponding fragment properties at scission are derived yielding fragment deformations, deformation energies, energy partitioning, neutron binding energies at scission, neutron multiplicities, charge polarization, and total fragment kinetic energies
International Nuclear Information System (INIS)
Low-alloyed tungsten alloys were obtained by melting with subsequent thermomechanical treatment under different conditions. The structure and substructure were studied by optical and electron microscopy methods. The width of X-ray diffraction lines was also determined to characterize microdistortions of the crystal lattice. The strength properties, plastic characteristics and ductile brittle transition temperature were determined in a 100-600 deg C temperature range under mechanical tensile tests. It is shown that in a high-deformed metal (degree of reduction approximately equal to 80% and more) the dislocation cell size governs some mechanical properties as well as the grain size determines there properties in a recrystallized state. It is shown that the structure parameters and mechanical properties of different tungsten alloys vary in dependence on t (deformation) in a similar way. The investigation also shows that the dispersed particle presence in a deformed tungsten alloy induces an indirect rather than direct strengthening
Mechanical properties of hot deformed Inconel 718 and X750
Nowotnik, A.; Pe?drak, P.; Sieniawski, J.; Go?ral, M.
2012-01-01
Purpose: Variations of a flow stress vs. true strain illustrate behavior of material during plastic deformation. Stress-strain relationship is generally evaluated by a torsion, compression and tensile tests.Design/methodology/approach: Compression tests were carried out on precipitations hardenable nickel based superalloys of Inconel 718 and X750 at constant true strain rates of 10-4, 4x10-4s-1 within temperature through which precipitation hardening phases process occurred (720-1150°C) usin...
Mathematical description of properties of a weakly deformed Gauss peak. 1
International Nuclear Information System (INIS)
The properties of the weakly deformed Gaussian peak are described by given formulas. The moment generating function and all the higher moments of this weakly deformed Gaussian peak density function are calculated by closed integrations. The density function is useful for the design of Maximum-Likelihood peak shape parameter estimators and the application of spectral techniques with multi-channel spectra. Numerical calculations use the well known Gaussian error integral and can be done by programmable microcomputers or programmable pocket calculators. (author)
Trumi? B.; Stankovi? D.; Ivanovi? A.
2010-01-01
In order to form the necessary data base on platinum and platinum metals, certain tests were carried out on platinum samples of different purity of 99.5%, 99.9% and 99.99%. The degree of cold deformation, annealing temperature and chemical assays were tested as well as their impact on the mechanical properties of platinum. The Vickers hardness (HV) values were determined with different deformation degree, starting from annealing temperatures for platinum of different purity and tensile streng...
DEFF Research Database (Denmark)
Huang, Xiaoxu
2009-01-01
The presence of a dislocation structure associated with low-angle dislocation boundaries and interior dislocations is a common and characteristic feature in nanostructured metals produced by plastic deformation, and plays an important role in determining both the strength and ductility of the nanostructured metals. The dislocation structure can be modified by post-process annealing and deformation which points to new ways of optimizing the mechanical properties. Such ways are demonstrated and discussed
Mechanical property of superplastic-deformed ceramics by micro-indentation method
International Nuclear Information System (INIS)
A neutron irradiation test on superplastic ceramic materials at high temperature has been proposed as an innovative basic research on high-temperature engineering using the High Temperature Engineering Test Reactor (HTTR). We investigated mechanical properties, such as the hardness and Young's modulus, of ceramic specimens after superplastic deformation. The tested material was 3Y-TZP (3mol% Yttria stabilized Tetragonal Zirconia Polycrystal) which is one of the representative superplastic ceramics. The properties were measured by a microindentation method. We also studied the relationship between crystal microstructures and the mechanical properties of deformed 3Y-TZP by scanning electron microscope (SEM). The indentation test showed that the mechanical properties of the specimens were reduced to about 1/2 by 30% deformation and to about 1/4 by 150% deformation. The SEM images showed that average grain size and deviation of grain size of each specimen increased with increasing deformation. From both the results, it was analytically shown that the increasing of the grain size was thought to be one of the causes of the reduction of the mechanical properties. (author)
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The stable structures and melting properties of ion clouds in isotropic octupole traps are investigated using a combination of semianalytical 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 follows the rule expected for three-dimensional dense particles, with a depression scaling linearly with the inverse radius.
Estimating the mechanical properties of the brittle deformation zones at Olkiluoto
International Nuclear Information System (INIS)
In rock mechanics modelling to support repository design and safety assessment for the Olkiluoto site, it is necessary to obtain the relevant rock mechanics parameters, these being an essential pre-requisite for the modelling. The parameters include the rock stress state, the properties of the intact rock and the rock mass, and the properties of the brittle deformation zones which represent major discontinuities in the rock mass continuum. However, because of the size and irregularity of the brittle deformation zones, it is not easy to estimate their mechanical properties, i.e. their deformation and strength properties. Following Section 1 explaining the motivation for the work and the objective of the Report, in Sections 2 and 3, the types of fractures and brittle deformation zones that can be encountered are described with an indication of the mechanisms that lead to complex structures. The geology at Olkiluoto is then summarized in Section 4 within the context of this Report. The practical aspects of encountering the brittle deformation zones in outcrops, drillholes and excavations are described in Sections 5 and 6 with illustrative examples of drillhole core intersections in Section 7. The various theoretical, numerical and practical methods for estimating the mechanical properties of the brittle deformation zones are described in Section 8, together with a Table summarizing each method's advantages, disadvantages and utility in estimating the mechanical properties of the zones. We emphasise that the optimal approach to estimating the mechanical properties of the brittle deformation zones cannot be determined without a good knowledge, not only of each estimation method's capabilities and idiosyncrasies, but also of the structural geology background and the specific nature of the brittle deformation zones being characterized. Finally, in Section 9, a Table is presented outlining each method's applicability to the Olkiluoto site. A flowchart is included to indicate the proposed structure for a brittle deformation zone mechanical property estimation campaign, noting that the exact nature of future work will depend on the results of the ONKALO Prediction-Outcome studies and decisions on the rock mechanics work required to support the repository design. (orig.)
Landau damping dynamic aperture and octupole in LHC
Gareyte, Jacques; Ruggiero, F
1997-01-01
Maximization of the dynamic aperture and Landau damping of the collective instabilities are partly conflicting requirements. On the one hand, the non-linearities of the lattice must be minimized at large oscillation amplitude to guarantee the stability of the single particle motion. On the other hand, a spread of the betatron frequencies is necessary to guarantee the stability of the collective motion of bunches of particles; this requires the introduction of non-linearities effective at small amplitudes. We show in this note that the `natural' spread of betatron tunes due to the field imperfections is inadequate or Landau damping. An octupole scheme is required to provide collective stability at high energy. At low energy it may be used to find the optimum between the correction of the octupolar field imperfections and Landau damping. The solution of the stability problem taking into account the two degrees of freedom of the transverse motion allows a significant saving in octupole strength: 144 octupoles wi...
High-spin states in sup(224,226,228)Th and the systematics of octupole effects in even Th isotopes
International Nuclear Information System (INIS)
High-spin states in sup(224,226,228)Th were investigated using conversion-electron and ?-ray spectroscopic methods following 226Ra(?,xn) reactions. The Ksup(?)=0+ and 0- rotational bands are observed, which in sup(224,226)Th merge into a single band characteristic for reflection asymmetric shape. The systematics of the level energies and E1 transition rates of 220-230Th are discussed in terms of a stable octupole deformation. (orig.)
Cyclic deformation and dynamic compressive properties of copper bicrystals
Energy Technology Data Exchange (ETDEWEB)
Yang, R.Q. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)], E-mail: rqyang@imr.ac.cn; Li, S.X.; Zhang, Z.F. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)
2007-09-25
Cyclic deformation and dynamic compressive tests of three copper bicrystals were carried out on a Shimadzu servo-hydraulic testing machine and a split Hopkinson pressure bar (SHPB) apparatus respectively. The post-deformation dislocation structures, grain boundary (GB) serrations and adiabatic shear bands (ASBs) were examined using electron channeling contrast (ECC) imaging in a scanning electron microscope (SEM). After cyclic straining the secondary slip bands were activated near the GB forming a GB affected zone (GBAZ). Microstructures beneath it are dislocation labyrinth or irregular persistent slip bands (PSBs). The saturation stress at GBAZ was calculated to be higher than that in the grain interior. In dynamic compression, the formation of ASBs, was found to be promoted by the GB. Dynamic stress-strain curves were compared with each other for single crystals, bicrystals and polycrystals. Microstructures were also characterized with orientation imaging microscopy (OIM) by electron backscattering diffraction (EBSD) technique. It was found that relatively larger lattice rotations occurred across the ASBs than in the other regions, which can be deduced by the localization of simple shear along ASBs. No recrystallization was found in the ASBs or along GBs in the present circumstance.
Gadenne, Leslie; Raimbourg, Hugues; Champallier, Rémi; Yamamoto, Yuzuru
2014-12-01
better constrain the mechanical behavior of sediments accreted to accretionary prism, we conducted triaxial mechanical tests on natural samples from the Miura-Boso paleo-accretionary prism (Japan) in drained conditions with confining pressures up to 200 MPa as well as postexperiments P-wave velocity (Vp) measurements. During experiments, deformation is principally noncoaxial and accommodated by two successive modes of deformation, both associated with strain-hardening and velocity-strengthening behavior: (1) compaction-assisted shearing, distributed in a several mm-wide shear zone and (2) faulting, localized within a few tens of ?m-wide, dilatant fault zone. Deformation is also associated with (1) a decrease in Young's modulus all over the tests, (2) anomalously low Vp in the deformed samples compared to their porosity and (3) an increase in sensitivity of Vp to effective pressure. We interpret this evolution of the poroelastic properties of the material as reflecting the progressive breakage of intergrain cement and the formation of microcracks along with macroscopic deformation. When applied to natural conditions, these results suggest that the deformation style (localized versus distributed) of shallow (z accretionary prisms by seismic imaging between 2 and 4 km depth could reflect sediment deformation rather than porosity anomalies.
International Nuclear Information System (INIS)
An excited superdeformed band in 194Hg , observed to decay directly to both normal-deformed and superdeformed yrast states, is proposed to be a K?=2- octupole vibrational band, based on its excitation energies, spins, and likely parity. The transition energies are identical to those of the yrast superdeformed band in 192Hg , but originate from levels with different spins and parities. The evolution of transition energies with spin suggests that cancellations between pairing and particle alignment are partly responsible for the identical transition energies. copyright 1997 The American Physical Society
Octupole correlations in the structure of 02+ bands in the N=88 nuclei 150Sm and 152Gd
Bvumbi, S. P.; Sharpey-Schafer, J. F.; Jones, P. M.; Mullins, S. M.; Nyakó, B. M.; Juhász, K.; Bark, R. A.; Bianco, L.; Cullen, D. M.; Curien, D.; Garrett, P. E.; Greenlees, P. T.; Hirvonen, J.; Jakobsson, U.; Kau, J.; Komati, F.; Julin, R.; Juutinen, S.; Ketelhut, S.; Korichi, A.; Lawrie, E. A.; Lawrie, J. J.; Leino, M.; Madiba, T. E.; Majola, S. N. T.; Maine, P.; Minkova, A.; Ncapayi, N. J.; Nieminen, P.; Peura, P.; Rahkila, P.; Riedinger, L. L.; Ruotsalainen, P.; Saren, J.; Scholey, C.; Sorri, J.; Stolze, S.; Timar, J.; Uusitalo, J.; Vymers, P. A.
2013-04-01
Knowledge of the exact microscopic structure of the 01+ ground state and first excited 02+ state in 150Sm is required to understand the branching of double ? decay to these states from 150Nd. The detailed spectroscopy of 150Sm and 152Gd has been studied using (?,xn) reactions and the ?-ray arrays AFRODITE and JUROGAM II. Consistently strong E1 transitions are observed between the excited K? = 02+ bands and the lowest negative parity bands in both nuclei. These results are discussed in terms of the possible permanent octupole deformation in the first excited K? = 02+ band and also in terms of the “tidal wave” model of Frauendorf.
The influence of plastic deformation on the magnetoelastic properties of the CSN12021 grade steel
Energy Technology Data Exchange (ETDEWEB)
Piotrowski, Leszek [Gdansk University of Technology, Faculty of Applied Physics and Mathematics, Narutowicza 11/12, 80-952 Gdansk (Poland)], E-mail: lesio@mif.pg.gda.pl; Augustyniak, Boleslaw; Chmielewski, Marek [Gdansk University of Technology, Faculty of Applied Physics and Mathematics, Narutowicza 11/12, 80-952 Gdansk (Poland); Tomas, Ivan [Institute of Physics, ASCR, Na Slovance 1, 18221 Praha 8 (Czech Republic)
2009-08-15
Magnetoelastic properties of materials are strongly influenced by changes of the dislocation structure that take place during the process of plastic deformation. Such changes can be used as a basis for a method of nondestructive evaluation (NDE) of the deformation level. So far, various methods, based on magnetic hysteresis loop properties as well as on the Barkhausen effect (BE), have been proposed. In the paper, the results obtained with the help of the abovementioned methods are compared with the results of the magnetoacoustic emission (MAE) signal measurements. The MAE signal is relatively easy to implement as a nondestructive method and unlike the BE effect signal gives information about the whole magnetized volume.
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.
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. 26 refs., 5 figs., 4 tabs
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.
Cryogenically cooled octupole ion trap for spectroscopy of biomolecular ions.
Boyarkin, Oleg V; Kopysov, Vladimir
2014-03-01
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. PMID:24689562
Cryogenically cooled octupole ion trap for spectroscopy of biomolecular ions
Boyarkin, Oleg V.; Kopysov, Vladimir
2014-03-01
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.
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.
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.
Effects of Dehydration on the Viscoelastic Properties of Vocal Folds in Large Deformations
Miri, Amir K.; Barthelat, François; Mongeau, Luc
2012-01-01
Dehydration may alter vocal fold viscoelastic properties, which may hamper phonation. The effects of water loss induced by an osmotic-pressure potential on vocal fold tissue viscoelastic properties were investigated. Porcine vocal folds were dehydrated by immersion in a hypertonic solution, and quasi-static and low-frequency dynamic traction tests were performed for elongations of up to 50%. Digital image correlation was used to determine local strains from surface deformations. The elastic m...
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.
Effects of deformation rates on mechanical properties of PP/SEBS blends
Balkan, O.; H. Demirer; E. Sabri Kayal?
2011-01-01
Purpose: The goal of this study is to examine effects of tensile deformation rates ( ) on tensile properties of polypropylene/poly(styrene-b-ethylene-co-butylene-b-styrene) copolymer (PP/SEBS) blends and to determine suitable for accurate and reliable evaluation of mechanical properties of the blends in accordance with the results of Izod impact tests.Design/methodology/approach: PP/SEBS blends containing ?e = 0, 2.5, 5 and 10 volume % of SEBS thermoplastic elastomer were compounded using...
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.
Mechanical Properties of Copper Processed by Severe Plastic Deformation.
Czech Academy of Sciences Publication Activity Database
Kunz, Ludvík
Rijeka : InTech, 2012 - (Collini, L.), s. 93-126 ISBN 978-953-51-0160-4 R&D Projects: GA ?R GAP108/10/2001 Keywords : copper * ultrafinegrained structure * fatigue properties * localization of cyclic plasticity Subject RIV: JL - Materials Fatigue, Friction Mechanics
An extended deformation model of 24Mg, 2
International Nuclear Information System (INIS)
Four rotational bands (K sup(?) = 0+, 2+, 0-, 3-) in the low-energy region of 24Mg are investigated with an extended deformation model which treats quadrupole (Y2) and octupole (Y3) deformations of the intrinsic one-body field and single-particle modes in it. The K sup(?) = 0+- bands are described as the inversion doublet with the lowest configuration in the deformed field and the K sup(?) = 2+ and 3- bands are constituted by their respective 1p-1h excited configurations. The Y2 + Y3-deformation which has been proposed through energy variation is well-substantiated by the electromagnetic properties pertaining to the four band. The present model successfully reproduces the enhanced E3-transition data between the K sup(?) = 0+- bands. The enhancement of these transitions is basically that of the Q3-moment of the intrinsic state which is caused by a collective correlation, i.e., the Y3-type of the deformation in the intrinsic state. The model also gives a good representation of the observed rotational character, i.e., the strong intra-band E2-transitions as well as the J(J + 1) rule in the energy spectrum both in the K sup(?) = 0+- bands and in the K sup(?) = 2+, 3- bands with the 1p-1h configurations. (author)
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...
Using octupoles for background control in linear colliders -- An exploratory conceptual study
International Nuclear Information System (INIS)
If one adds a suited Octupole (or an even higher multipole) lattice to linear collider Quadrupole FODO lattices, the amplifying properties of the combined lattice drive particles in the tails, but not those in the core, into resonant losses. This approach is quite different in concept and beam dynamics impact from past proposed use of non-linear elements for collimation. This non-traditional scheme for background control has the added advantage that most, or maybe all, of the Halo collimation can be done using the lever arm of the real estate of the main accelerators, thus reducing the costly length of a separate dedicated collimation section and also unifying machine protection and background control. Simulations of particle distributions are presented. This approach requires cooperation by the designers of the accelerators, the beam delivery system, and the Detector, because a careful balance between sometimes conflicting requirements has to be found. As a second component of this approach the use of Octupoles right before the final focusing Quadrupoles is proposed in order to enlarge the effective beam stay clear by a factor of 2--3, thus reducing the requirements for collimation. This concept would reduce the requirement for collimation but simulation have not been carried out here in detail. To further explore and implement this concept will require a considerable effort in manpower, possibly comparable to, although less in scope, than the effort to develop the Nin scope, than the effort to develop the NLC RF or the CLIC RF schemes
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
International Nuclear Information System (INIS)
The low-temperature internal friction Q-1, thermal conductivity ?, specific heat cp and heat release of plastically deformed, high-purity aluminum polycrystals have been investigated and have been compared with measurements on an amorphous SiO2 specimen. Plastic deformation has a pronounced effect on both internal friction Q-1 and thermal conductivity ? in the superconducting state. The magnitude of the internal friction Q-1 can be increased over two orders by plastic deformation over that observed on an annealed sample, and approaches a value approximately equal to that of the amorphous SiO2 specimen. The lattice thermal conductivity ? of the deformed specimens also has a magnitude which is of the same order as that of amorphous SiO2, it is, however, nearly independent of the amount of deformation. No ''glass-like'' anomalies could be observed in the specific heat cp and heat release measurements. The specific heat cp approaches a T3-relationship at the lowest temperatures investigated, and heat release experiments clearly show no long-time energy relaxation effects. Thus, it must be concluded that the defects introduced into deformed aluminum cannot be described with the tunneling model which had been proposed to describe the low temperature elastic and thermal properties of amorphous solids and which is based on the assumption of a constant spectral dens assumption of a constant spectral density of tunneling states. The phonon scattering mechanism observed in the deformed aluminum is tentatively related to the interaction of phonons with geometrical kinks in dislocations. (orig.)
Microstructure, Properties and Atomic Level Strain in Severely Deformed Rare Metal Niobium
Directory of Open Access Journals (Sweden)
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
Directory of Open Access Journals (Sweden)
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.
Effect of Nb content on deformation behavior and shape memory properties of Ti–Nb alloys
International Nuclear Information System (INIS)
Highlights: ? Reorientation of martensite variants occurred by the deformation of the {1 1 1} type I and ?2 1 1? type II twins. ? Magnitude of twinning shear in Ti–20Nb is larger than that in Ti–23Nb. ? Ti–20Nb exhibited a higher stress for the reorientation of martensite variants when compared with Ti–23Nb. -- Abstract: Deformation behavior and shape memory properties of Ti–(20, 23) at.% Nb alloys in a single ?? martensite state were investigated. The Ti–20Nb alloy exhibited a higher stress for the reorientation of martensite variants when compared with the Ti–23Nb alloy. The recovery strain due to the shape memory effect in the Ti–20Nb alloy was smaller than that in the Ti–23Nb alloy. Transmission electron microscope (TEM) observation revealed that the reorientation of martensite variants occurred by the deformation of {1 1 1} type I and ?2 1 1? type II twins. The Nb content dependence of the deformation behavior and shape memory properties was discussed considering the magnitude of twinning shear of the twins
Effect of Nb content on deformation behavior and shape memory properties of Ti–Nb alloys
Energy Technology Data Exchange (ETDEWEB)
Tobe, H. [Division of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Kim, H.Y., E-mail: heeykim@ims.tsukuba.ac.jp [Division of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Inamura, T.; Hosoda, H. [Precision and Intelligence Laboratory, Tokyo Institute of Technology, Yokohama 226-8503 (Japan); Nam, T.H. [School of Materials Science and Engineering and ERI, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of); Miyazaki, S., E-mail: miyazaki@ims.tsukuba.ac.jp [Division of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); School of Materials Science and Engineering and ERI, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of); Center of Excellence for Advanced Materials Research, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia)
2013-11-15
Highlights: ? Reorientation of martensite variants occurred by the deformation of the {1 1 1} type I and ?2 1 1? type II twins. ? Magnitude of twinning shear in Ti–20Nb is larger than that in Ti–23Nb. ? Ti–20Nb exhibited a higher stress for the reorientation of martensite variants when compared with Ti–23Nb. -- Abstract: Deformation behavior and shape memory properties of Ti–(20, 23) at.% Nb alloys in a single ?? martensite state were investigated. The Ti–20Nb alloy exhibited a higher stress for the reorientation of martensite variants when compared with the Ti–23Nb alloy. The recovery strain due to the shape memory effect in the Ti–20Nb alloy was smaller than that in the Ti–23Nb alloy. Transmission electron microscope (TEM) observation revealed that the reorientation of martensite variants occurred by the deformation of {1 1 1} type I and ?2 1 1? type II twins. The Nb content dependence of the deformation behavior and shape memory properties was discussed considering the magnitude of twinning shear of the twins.
Farh, Hichem; Guemini, Rebai; Serradj, Fares; Djemmal, Karim
2010-01-01
An investigation has been done to study the effect of deformation ratio and two-step ageing treatment on the microstructure and the mechanical properties in an Al-Mg-Si aluminum alloy. Transmission electron microscopy is used in order to follow the distribution and the morphology of the hardening precipitates. The hardness of the alloy increases with the increasing deformation ratio. The maximum of hardness increases and is shifted to low time with an increase of the deformation ratio...
Effects of deformation rates on mechanical properties of PP/SEBS blends
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O. Balkan
2011-07-01
Full Text Available Purpose: The goal of this study is to examine effects of tensile deformation rates ( on tensile properties of polypropylene/poly(styrene-b-ethylene-co-butylene-b-styrene copolymer (PP/SEBS blends and to determine suitable for accurate and reliable evaluation of mechanical properties of the blends in accordance with the results of Izod impact tests.Design/methodology/approach: PP/SEBS blends containing ?e = 0, 2.5, 5 and 10 volume % of SEBS thermoplastic elastomer were compounded using a twin-screw extruder, and then moulded with an injection moulding machine. Morphology of PP/SEBS blends were analysed by scanning electron microscopy (SEM. Mechanical properties of the blends were investigated tensile and Izod impact tests. Tensile deformation rates 1= 1.67 ms–1 and 2 = 16.67 ms–1 were used to determine ultimate tensile properties.Findings: Morphological analyses revealed that SEBS elastomer particles were well-dispersed throughout PP matrix in irregular forms with a narrow size distribution and evidenced a two-phase system formation. At low deformation rate ( 1, PP and PP/SEBS blends did not fail during tensile tests despite maximum tensile deformation, ?max = 600%; therefore, tensile toughness (UT, stress and strain values at break point (?b and ?b of the blends were not determined. However, at high deformation rate ( 2, all specimens tested in this study failed; a slight decrease in ?b of the blends with SEBS elastomer was associated with a significant increase in ?b and UT. Strain-rate-sensitivity of PP/SEBS blends was promoted with SEBS elastomer.Research limitations/implications: Mechanical properties determined through high-velocity tests are beyond the scope of this study.Practical implications: of tensile testing machines is readily adjustable, while ?max of tensile testing machines is limited. Consequently, in order to evaluate reliably mechanical properties of ductile materials like PP/SEBS blends, must be so high that ductile materials can fail during tensile tests.Originality/value: Tensile testing at high strain rate 2 was concluded to be more suitable for evaluation of mechanical properties of PP/SEBS blends than that of at low strain rate.
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
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
Influence of plastic deformation on the properties of ferritic corrosion-resistant steels
Energy Technology Data Exchange (ETDEWEB)
Sorokina, N.A.; Andrushova, N.V.; Gal`tsova, V.I.; Kaputkin, I.I.
1992-01-01
As the result of features of their crystalline structure with a body-centered cubic lattice ferritic chromium corrosion-resistant steels, used primarily in the form of thin cold-rolled sheets for formed parts of industrial and domestic machinery, are very sensitive to a change in mechanical properties under the influence of plastic deformation. Three groups of corrosion resistant steels were investigated. 3 figs., 1 tab.
Variation of hydraulic properties on sedimentary rock due to shear deformation
International Nuclear Information System (INIS)
In order to investigate the variation of hydraulic properties on soft rock due to shear deformation, permeability tests were performed on hard shale of the Wakkanai formation by axial flow and radial flow techniques under triaxial compression. The experimental results showed that the axial direction permeability increased to approximately 10 times larger than the initial one in residual strength zone. On the other hand, the radial direction permeability increased remarkably in strain softening zone. (author)
Yang, Xiaoping; Dong, Jinming
2007-01-01
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 l...
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.
Haidar, B.; Vidal, A.
1996-01-01
The physical aging concept is generally used to explain the typical behavior of amorphous glassy materials such as amorphous polymers after different annealing or temperature quenching . In this work it is evidenced by measuring, on already aged specimens, the effect of deformation on the dynamic mechanical properties of several amorphous polymers (polycarbonate, polyetherimide and a styrene butadiene copolymer). For a static extension of 3 %, E' at an amplitude of ? 0.01 % was determined f...
Astafurova, E. G.; Tukeev, M. S.; Chumlyakov, Yu. I.
2007-10-01
The role of aluminum alloying on strength properties and deformation mechanisms (slip, twinning) of single crystals of Hadfield steel under tensile loading at T = 300 K is demonstrated. It is found out that aluminum alloying suppresses twinning deformation in the single crystals and, during slip, results in a dislocation structure change from a uniform dislocation distribution to a planar dislocation structure.
Fatigue properties of magnesium alloy AZ91 processed by severe plastic deformation.
Fintová, Stanislava; Kunz, Ludvík
2015-02-01
Fatigue properties of cast AZ91 magnesium alloy processed by severe plastic deformation were investigated and compared with the properties of the initial cast state. The severe plastic deformation was carried out by equal channel angular pressing (ECAP). The ECAP treatment resulted in a bimodal structure. The bimodality consists in a coexistence of fine grained areas with higher content of Mg17Al12 particles and areas exhibiting larger grains and lower density of Mg17Al12 particles. Improvement of the basic mechanical properties of AZ91 (yield stress, tensile strength and ductility) by ECAP was significant. Also the improvement of the fatigue life in the low-cycle fatigue region was substantial. However the improvement of the fatigue strength in the high-cycle fatigue region was found to be negligible. The endurance limit based on 10(7) cycles for the cast alloy was 80 MPa and for the alloy processed by ECAP 85 MPa. The cyclic plastic response in both states was qualitatively similar; initial softening was followed by a long cyclic hardening. Fatigue cracks in cast alloy initiate in cyclic slip bands which were formed in areas of solid solution. In the case of severe plastic deformed material with bimodal structure two substantially different mechanisms of crack initiation were observed. Crack initiation in slip bands was a preferred process in the areas with large grains whereas the grain boundaries cracking was a characteristic mechanism in the fine grained regions. PMID:25498295
The petrophysical properties of deformation bands in relation to their microstructure
Ogilvie, Steven R.; Glover, Paul W. J.
2001-11-01
Deformation bands are significant discontinuities in reservoir sandstones providing baffles to the migration of fluids and acting as seals for hydrocarbon accumulations. Their contribution to these processes is dependent upon a range of inter-related factors including lateral continuity, relative displacement, reservoir geohistories and rock microstructure. Deformation bands have millimetre-scale displacements, which are smaller than the seismic resolution, and hence the study of their microstructure from reservoir cores is a necessary tool in the prediction of their fault seal potential. The latter is only achieved if detailed petrophysical measurements of fault microstructure are carried out using techniques, which are suitable for measurement of very low permeability fault rock at the relevant scale. Conventional techniques of fault rock porosity and permeability determination invite host rock bias in measurement and inevitably underestimate the potential of these structures as fluid barriers. Pressure decay probe permeametry used in this study has the advantage of measuring small volumes of rock at finer spatial resolutions and detailed permeability distributions around common types of deformation bands are obtained. Together with supporting data provided by conventional core analysis techniques, these measurements show that the greatest differences in petrophysical properties relative to host rock occur in those bands, which have experienced cataclasis. These results provide valuable input into reservoir simulation models and help reduce much of the uncertainty regarding the role of different types of deformation bands in fault seal.
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 Retrasse 10, D-8520 Erlangen, Federal Republic of Germany). Details of the measurements are described in the paper. (orig.)
1986-01-01
Skeletal proteins play an important role in determining erythrocyte membrane biophysical properties. To study whether membrane deformability and stability are regulated by the same or different skeletal protein interactions, we measured these two properties, by means of ektacytometry, in biochemically perturbed normal membranes and in membranes from individuals with known erythrocyte abnormalities. Treatment with 2,3-diphosphoglycerate resulted in membranes with decreased deformability and de...
International Nuclear Information System (INIS)
This paper addresses a new characterization of (R,p,q)-deformed Rogers–Szegö polynomials by providing their three-term recurrence relation and the associated quantum algebra built with corresponding creation and annihilation operators. The whole construction is performed in a unified way, generalizing all known relevant results which are straightforwardly derived as particular cases. Continuous (R,p,q)-deformed Hermite polynomials and their recurrence relation are also deduced. Novel relations are provided and discussed. (paper)
Property optimization of nanostructured ARB-processed Al by post-process deformation
DEFF Research Database (Denmark)
Huang, Xiaoxu; Kamikawa, Naoya
2008-01-01
The effect of post-process deformation on the mechanical properties of nanostructured aluminum (99.2% purity) has been investigated by cold rolling of samples which have been processed by accumulative roll bonding (ARB) to a strain of epsilon(vM) = 4.8. Samples have been cold rolled to 10, 15, and 50% reductions and ultimate tensile strength (UTS), yield stress and elongation have been determined by tensile testing at room temperature. The mechanical testing shows that cold rolling to low strains (10% and 15%) leads to softening and increase in elongation compared to the as-processed ARB material. In contrary, cold rolling to large strain (50%) results in significant strengthening. This leads to the suggestion of a transition strain within the range of 25-35% reduction by rolling. The microstructural evolution during post-process deformation has been followed by transmission electron microscopy showing a significant change in the dislocation structure when the strain is increased. Based on the experimental observations the mechanical behavior is related to the structural changes focusing on the characteristics of the dislocation structure present between the narrowly spaced lamellar boundaries in the deformed 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.
Klein, Emilie; Fleitout, Luce; Vigny, Christophe
2015-04-01
The interseismic and postseismic deformations preceding and following the large subduction earthquake of Maule (Chile, Mw8.8, 2010) have been closely monitored with GPS from 70 km up to 2000 km away from the trench. Post-seismic deformations exhibit a behavior generally similar to that already observed after the Aceh and Tohoku-Oki earthquakes: vertical uplift is observed on the oceanward side of the volcanic arc. A moderate large scale subsidence is associated with sizeable horizontal deformation in the far-field (500-2000km from the trench). In addition, near-field data (70-200km from the trench) feature a rather complex deformation pattern. A 3D FE code (Zebulon Zset) is used to relate these deformations to the mechanical properties of the mantle and of the subduction interface. The mesh features a spherical shell-portion from the core-mantle boundary to the Earth's surface, extending over more than 60 degrees in latitude and longitude. The overridding and subducting plates are elastic, and the asthenosphere is viscoelastic. We test the presence and shape of two low viscosity areas in the mantle : a low viscosity wedge (LVW) above the subducting plate extending beneath the volcanic arc, and a narrow low viscosity channel (LVCh) along the lower part of the subduction interface, and potentially deeper. All the viscoelastic regions feature a Burgers rheology and we invert for their mechanical properties and geometrical characteristics. Our best fitting models present, (i) an asthenosphere extending down to 270km, with a 'long-term' viscosity of the order of 3.1018Pa.s; (ii) a LVCh along the plate interface extending from depths of 50 to 150 km with viscosities slightly below 1018 Pa.s; (iii) a LVW restricted to the base of the lithosphere below the volcanic arc, with viscosities of a few 1018 Pa.s. Increased horizontal velocities are due to relaxation in both the asthenosphere and the LVCh. A deep channel is necessary to produce enough uplift in the middle-field (200-500km from the trench). Some additional slip on the plate interface, at shallow depth, is also necessary to explain all the characteristics of the near-field displacements.
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.
International Nuclear Information System (INIS)
The effect of plastic deformation and subsequent annealing on the magnetic properties and microstructure of a grain-oriented (GO) electrical steel has been studied. True strain (?) from 0.002 to 0.23 was applied by rolling in two directions, rolling (RD) and transverse (TD). The deterioration of power losses varies according to the direction of deformation. Annealing the strained material-at 800 deg. C/2 h-leads to a recrystallization and restored magnetic properties. The main components of annealed-textures are around 15-35o from those of deformed-textures for both RD and TD. Rolling along {1 1 0} direction leads to the development of deformation twins
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.
International Nuclear Information System (INIS)
Mechanical, magnetic and thermal properties of quenched (1150 deg C, water) alloys N36K10T3, N36K10Kh5T2, N36K5T2 are investigated after age hardening (650 deg C) and high temperature deformation (1100-800 deg C) with subsequent ageing. It is shown that supersaturated solid solution decomposition in invar alloys studied results in an increase of strength properties and coercive force but decreases ductility and saturation magnetization. Plastic deformation of invars is revealed to enhance ultimate strength, yield strength and coercive force. Additional ageing of deformed materials increases strength properties and decreases plastic ones. Saturation magnetization correlates best with mechanical properties compared to other magnetic parameters
Structure and properties of deformed alloys of tungsten-rich corner of W-Mo-Re-Hf-C system
International Nuclear Information System (INIS)
Main regularities of structure formation and mechanical properties changing are established for deformation of vacuum-melted low alloys in W-Mo-Re-Hf-C system. It is shown that during hot deformation a fibrous structure is formed which provides a dec-- crease of ductile-brittle transition temperature. All the alloys investigated after a 95% reduction are ductile at room temperature. Hot deformation in the range 1450-1350 deg C with 92-93% re-- duction in area does not result in a visible increase of alloy ultimate strength
Microstructure and properties of ceramics and composites joined by plastic deformation
International Nuclear Information System (INIS)
A review is presented of the design of suitable materials systems for joining by high-temperature plastic deformation, details of the joining techniques, microstructures and properties of the resulting composite bodies, and prospects and limitation for this type of joining technology. Joining parameters and resulting forms are discussed for Al2O3/mullite particulate composites, Y2O3-stabilized ZrO2 particulate/Al2O3 particulate and whisker-reinforced composites, hydroxyapatite bioceramics, La0.85Sr0.15MnO3 electronic ceramics, MgF2 optical ceramics, and Ni3Al intermetallics. Results are contrasted with those obtained by other methods of joining brittle, high-temperature materials, with special focus on durability and mechanical properties
Energy Technology Data Exchange (ETDEWEB)
Dudek, J.
1987-01-01
Mechanisms influencing the behavior of superdeformed nuclei are studied using several well established nuclear structure techniques. In particular: pairing, thermal excitation, shell and liquid-drop mechanisms are considered. The effects of quadrupole and hexadecapole (both axial and non-axial), and octupole deformation degrees of freedom are studied. Most of the results are illustrated using the case of /sup 152/Dy nucleus in which a superdeformed band extending up to I approx. 60 h-bar has been found in experiment. Some comparisons between /sup 152/Dy and the nuclei in the neighborhood are given. Calculations show that pairing ''de-aligns'' typically 6 to 8 units of angular momentum, as compared to the corresponding rigid rotation. This takes place for spins extending up to the highest limit, and thus diminishes the effective moments of inertia. Predicted octupole shape susceptibility is extremely large, significantly stronger than the susceptibilities known in the ground-states of many Actinide nuclei. Consequences of this result for the near-constancy of the dynamical moments of inertia are pointed out. Nuclear level densities calculated in function of spin, excitation energy and deformation explain the ''unusual'' side feeding pattern of the /sup 152/Dy superdeformed states. Predictions of super-superdeformed nuclear states (axis ratio varying between 2:1 and 3:1 or more) are given and exemplified for Erbium nuclei. Finally, the problem of superdeformation stability and the influence of increased collective inertia on a barrier penetration are examined. An analytical expression for the effective inertia parameter is obtained and its derivation outlined. 35 refs., 9 figs.
International Nuclear Information System (INIS)
Mechanisms influencing the behavior of superdeformed nuclei are studied using several well established nuclear structure techniques. In particular: pairing, thermal excitation, shell and liquid-drop mechanisms are considered. The effects of quadrupole and hexadecapole (both axial and non-axial), and octupole deformation degrees of freedom are studied. Most of the results are illustrated using the case of 152Dy nucleus in which a superdeformed band extending up to I ? 60 h-bar has been found in experiment. Some comparisons between 152Dy and the nuclei in the neighborhood are given. Calculations show that pairing ''de-aligns'' typically 6 to 8 units of angular momentum, as compared to the corresponding rigid rotation. This takes place for spins extending up to the highest limit, and thus diminishes the effective moments of inertia. Predicted octupole shape susceptibility is extremely large, significantly stronger than the susceptibilities known in the ground-states of many Actinide nuclei. Consequences of this result for the near-constancy of the dynamical moments of inertia are pointed out. Nuclear level densities calculated in function of spin, excitation energy and deformation explain the ''unusual'' side feeding pattern of the 152Dy superdeformed states. Predictions of super-superdeformed nuclear states (axis ratio varying between 2:1 and 3:1 or more) are given and exemplified for Erbium nuclei. Finally, the problem of superdeformation stability and the influence of increased collective inertia on a barrier penetration are examined. An analytical expression for the effective inertia parameter is obtained and its derivation outlined. 35 refs., 9 figs
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Cu–Ge alloys with different stacking fault energies (SFEs) were prepared by induction melting and processed by severe plastic deformation (SPD) using three different deformation techniques, including rolling at room temperature (RTR), rolling at the liquid nitrogen temperature (LNR), and Split Hopkinson Pressure Bar (SHPB) impact followed by room temperature rolling (HK+RTR). The effects of SFE, strain rate and deformation temperature on the microstructures and mechanical properties were systematically investigated by X-ray diffraction analyses and tensile tests. It was found that the dislocation density and twin density of all the Cu alloys after the SPD processing increased with decreasing SFE, increasing strain rate or reducing deformation temperature, which led to simultaneously enhanced strength and improved ductility due to effective grain refinement. The mechanical properties of the Cu alloys can be optimized to a combination of high strength and excellent ductility by lowering the SFE, the intrinsic property of metals, or manipulating the extrinsic deformation conditions, that is, increasing strain rate, and/or decreasing deformation temperature
On the relationship between forearc deformation, frictional properties and megathrust earthquakes
Cubas, Nadaya; Singh, Satish
2014-05-01
A better understanding of the relation between the structural geology and the morphology of forearc wedges with frictional properties could provide insights on earthquake mechanics. Therefore, we study, with simple mechanical analysis allowing for inverse studies, the three subduction zones that produced the major earthquakes of the 21st century : Central Chile (Maule 2010 Mw 8.8), NE Japan (Tohoku-Oki 2011 Mw 9.0) and Sumatra (Sumatra-Andaman 2004 Mw 9.1, Nias 2005 Mw 8.7). We first apply the critical taper theory that yields the effective friction of the subduction interface, the wedge internal friction and pore fluid pressure. We then apply the limit analysis approach to constrain variations of frictional properties along the megathrust from the location and style of forearc faulting. We show that seismic ruptures most often coincide with the mechanically stable part of the wedge whereas regions undergoing aseismic slip are at critical state, consistent with evidence for active deformation. In the rupture area, we found a low effective dynamic friction, probably reflecting strong dynamic weakening. Where no frontal rupture was observed, we obtain intermediate values of long-term effective friction along the frontal aseismic zone, implying hydrostatic pore pressure. On the contrary, where the rupture reached the seafloor (Tohoku-Oki earthquake, parts of the Sumatra-Andaman 2004 earthquake), a very low long-term effective friction and a high pore pressure are observed. The difference of properties of the frontal wedge might reflect differences in permeability. A lower permeability would enhance dynamic weakening and allow for frontal propagation of ruptures. We also show that spatial variations of frictional properties between aseismic and seismogenic zones can lead to the activation of splay faults. We also show that a high pore pressure along accretionary wedges can change the vergence of frontal thrusts. As a consequence, wedge morphology and deformation can be used to improve seismic and tsunamigenic risk assessment.
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.
Structure and properties of deformed 15Kh1M1F steel after long-term aging
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The structure and mechanical properties of 15Kh1M1F steel tubes were studied at 20 and 570 deg C following deformation and long-term aging at 600-620 deg C during 2200-7000 h, that is equivalent to 100 and 200 th.h. exposure at 540-570 deg C. It has been established that steel with the ferrite-carbide structure is less heat resistant as compared to the bainite structure. No visible changes in the bainite colony structure are observed after long-term aging. Tempering after deformation considerably weakens the effect of aging on the mechanical properties. Aging during 100 th.h. at operation temperature levels off the differences in tempered and nontempered deformed metal properties
Effects of dehydration on the viscoelastic properties of vocal folds in large deformations.
Miri, Amir K; Barthelat, François; Mongeau, Luc
2012-11-01
Dehydration may alter vocal fold viscoelastic properties, thereby hampering phonation. The effects of water loss induced by an osmotic pressure potential on vocal fold tissue viscoelastic properties were investigated. Porcine vocal folds were dehydrated by immersion in a hypertonic solution, and quasi-static and low-frequency dynamic traction tests were performed for elongations of up to 50%. Digital image correlation was used to determine local strains from surface deformations. The elastic modulus and the loss factor were then determined for normal and dehydrated tissues. An eight-chain hyperelastic model was used to describe the observed nonlinear stress-stretch behavior. Contrary to the expectations, the mass history indicated that the tissue absorbed water during cyclic extension when submerged in a hypertonic solution. During loading history, the elastic modulus was increased for dehydrated tissues as a function of strain. The response of dehydrated tissues was much less affected when the load was released. This observation suggests that hydration should be considered in micromechanical models of the vocal folds. The internal hysteresis, which is often linked to phonation effort, increased significantly with water loss. The effects of dehydration on the viscoelastic properties of vocal fold tissue were quantified in a systematic way. A better understanding of the role of hydration on the mechanical properties of vocal fold tissue may help to establish objective dehydration and phonotrauma criteria. PMID:22483778
FlexyDos3D: a deformable anthropomorphic 3D radiation dosimeter: radiation properties
De Deene, Y.; Skyt, P. S.; Hil, R.; Booth, J. T.
2015-02-01
Three dimensional radiation dosimetry has received growing interest with the implementation of highly conformal radiotherapy treatments. The radiotherapy community faces new challenges with the commissioning of image guided and image gated radiotherapy treatments (IGRT) and deformable image registration software. A new three dimensional anthropomorphically shaped flexible dosimeter, further called ‘FlexyDos3D’, has been constructed and a new fast optical scanning method has been implemented that enables scanning of irregular shaped dosimeters. The FlexyDos3D phantom can be actuated and deformed during the actual treatment. FlexyDos3D offers the additional advantage that it is easy to fabricate, is non-toxic and can be molded in an arbitrary shape with high geometrical precision. The dosimeter formulation has been optimized in terms of dose sensitivity. The influence of the casting material and oxygen concentration has also been investigated. The radiophysical properties of this new dosimeter are discussed including stability, spatial integrity, temperature dependence of the dosimeter during radiation, readout and storage, dose rate dependence and tissue equivalence. The first authors Y De Deene and P S Skyt made an equivalent contribution to the experimental work presented in this paper.
Ansari, R.; Rouhi, S.; Ajori, S.
2014-01-01
This paper aims to compute the elastic properties and large deformation of two-dimensional silicene, a low buckled honeycomb structure of silicon, under uniaxial and biaxial tension by implementing molecular dynamics simulations in canonical ensemble (NVT). The results demonstrate that Young's and bulk moduli and ultimate stress of silicene nanosheet are lower than those of graphene. Ultimate strain is found to be higher than that of graphene for armchair silicene, unlike the zigzag one. Moreover, Poisson's ratio of silicene is found to be greater than that of its carbon counterpart due to longer Si-Si bond length and its low buckled honeycomb structure. Further, it is observed that bulk modulus is strongly size-dependent and it decreases by increasing the length of nanosheet. Finally, the silicene behavior under large deformation and fracture pattern are investigated and the formation of topological defects and silicon chains are observed. It is further revealed that the silicene is noticeably weaker than graphene in zigzag direction.
FlexyDos3D: a deformable anthropomorphic 3D radiation dosimeter: radiation properties.
De Deene, Y; Skyt, P S; Hil, R; Booth, J T
2015-02-21
Three dimensional radiation dosimetry has received growing interest with the implementation of highly conformal radiotherapy treatments. The radiotherapy community faces new challenges with the commissioning of image guided and image gated radiotherapy treatments (IGRT) and deformable image registration software.A new three dimensional anthropomorphically shaped flexible dosimeter, further called 'FlexyDos3D', has been constructed and a new fast optical scanning method has been implemented that enables scanning of irregular shaped dosimeters. The FlexyDos3D phantom can be actuated and deformed during the actual treatment. FlexyDos3D offers the additional advantage that it is easy to fabricate, is non-toxic and can be molded in an arbitrary shape with high geometrical precision.The dosimeter formulation has been optimized in terms of dose sensitivity. The influence of the casting material and oxygen concentration has also been investigated. The radiophysical properties of this new dosimeter are discussed including stability, spatial integrity, temperature dependence of the dosimeter during radiation, readout and storage, dose rate dependence and tissue equivalence. PMID:25615261
Energy Technology Data Exchange (ETDEWEB)
Farbaniec, Lukasz; Dirras, Guy [Universite Paris 13, Sorbonne Paris Cite LSPM-CNRS, 99, Avenue J. B. Clement, 93430 Villetaneuse (France); Abdul-Latif, Akrum [Laboratoire d' Ingenierie des Systemes Mecaniques et des Materiaux 3, Rue Fernand Hainaut, 93407 St. Ouen Cedex (France); Gubicza, Jeno [Department of Materials Physics, Eoetvoes Lorand University Budapest, P.O. Box 32, H-1518 (Hungary)
2012-11-15
Bulk ultrafine-grained samples are processed by dynamic plastic deformation at an average strain rate of 3.3 x 10{sup 2} s{sup -1} from bulk coarse-grained nickel with purity higher than 98.4 wt.%. The obtained microstructure is investigated by electron backscattering diffraction, transmission electron microscopy and X-ray line profile analysis. After dynamic deformation the microstructure evolves into submicron-size lamellar and subgrain structures. Evaluation of average grain size shows a heterogeneous microstructure along both the diameter and the thickness of the sample. X-ray line profile analysis reveals high dislocation density of about 13 {+-} 2 x 10{sup 14} m{sup -2} in the impacted material. The mechanical properties are investigated by means of uniaxial quasi-static compression tests conducted at room temperature. The stress-strain behavior of the impacted Ni depends on the location in the impacted disk and on the orientation of the compression axis relative to the impact direction. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Strength and deformational properties of concrete at elevated temperatures up to 5000C
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Mechanical property tests of concrete at elevated temperatures had been performed. The experimental results obtained by the strength tests, were shown at each strength test. Compressive strength: sigmacu(T)/sigmacu, room = 1.00(normal temp. 0C), sigmacu(T)/sigmacu, room = -0.00195T + 1.544(280 0C -6T2 + 4.813 x 10-5T + 1.0(normal temp. 0C); Modulus of Rupture: sigmabu(T)/sigmabu, room = -0.0021T + 1.402(100 0C 0C); Young's Modulus: Esub(c)(T)/Esub(c), room = -0.00124T + 0.802(100 0C 0C); Relationship between Decrease rates of Young's Modulus(W) and Weight of Test Specimen(G): W = 0.047G + 2.88(100 0C 0C); compressive Strain at the Maximum Stress: R strain = 0.00263T + 0.932(normal temp. 0C), which means the ratio of the compressive strain at maximum stress at high temperature to that at normal temperature. It was made clear by the past researches that the thermal expansion coefficients of deformed bars increase according to temperature rise. The experimental results obtained by the free expansion tests using D16 deformed bars in Civil Engineering Laboratory supported the general tendency described above. Further, the strengths as well as Young's modulus of concrete at es well as Young's modulus of concrete at elevated temperatures were discussed. (Kubozono, M.)
Phase composition and properties of the deformed 12Kh18N10T steel after long-term heatings
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Studied is the change of the 12Kh18N10T steel properties, the steel being subjected to cold, warm and high temperature deformation in the process of long-term heatings at 550-850 deg C. The methods of chemical and differential phase analyses are used. The data of investigation show that plastic deformation considerably increases the precipitation of the ? phase and TiC, and (Ti, Ni)6C carbides in the 12Kh18N10T steel, its intensifying effect being considerably decreased at the increase of rolling temperature from 20 up to 1000 deg C. The deformation decreases the steel impact strength after the long-term holdings at 650 deg C. The structure produced at high-temperature deformation posess the higher stability under long-term heating at 650 deg C
Roy, Indranil
The mechanisms of deformation and fracture evolution in fully dense bulk Ni specimens as a function of its grain size, micro to nanocrystalline (nc) were determined from results of uniaxial tensile tests. Transmission electron micrographs of fractured gauge sections indicated that the deformation mechanism in specimens having an average grain size of 20 nm to be generally dictated by nanovoid formation at grain boundaries (GBs), collective motion of grains, grain rotation, and some twinning. With increase in the grain size the primary mechanism of fracture changed to twinning deformation and some dislocation activity, subsequently to a complete dislocation accommodated deformation in microcrystalline specimens. Bulk electrodeposited (ED) nc-Ni having an average grain size of 100 nm was selected as a model material to investigate salient mechanical properties/physical attributes because of its important attributes. First, it was observed to have better stability as compared to its finer grained counterparts; second, it had a grain size in the transition region between nanocrystalline and ultrafine grained (UFG) materials. The effect of strain rate on strength and ductility, corresponding strain rate sensitivity and activation volume were determined from uniaxial tensile tests and strain jump tests conducted selectively at 393 and 413 K. Results indicated that while there is an increase in strength with increasing strain rate at a constant temperature, ductility followed a negative correlation with increasing strain rate. It is clear that strengthening materials through grain refinement often results in reduced ductility necessitating means to augment their elongation to failure. An approach to simultaneously enhance both strength and ductility by engineering its grains through introduction of annealing twins and increasing the volume fraction of coherent low sigma boundaries was invented. Corrosion resistance has been demonstrated to be significantly superior in several ED nc-metals and alloys as compared to their coarse grained counterparts. Based on orientation imaging microscopy (OIM) performed to produce electron backscatter diffraction (EBSD) maps, it was observed that GBs in ED nc-Ni are predominantly Sigma3s. The superior corrosion resistance of ED nc-Ni is attributed to this large volume fraction of naturally occurring coherent low sigma coincidence site lattice (CSL) boundaries.
Deformation mechanisms, length scales and optimizing the mechanical properties of nanotwinned metals
International Nuclear Information System (INIS)
Refinement of microstructural length scales and modification of interface character offer opportunities for optimizing material properties. While strength and ductility are commonly inversely related, nanotwinned polycrystalline copper has been shown to possess simultaneous ultrahigh strength and ductility. Interestingly, a maximum strength is found at a small, finite twin spacing. We study the plastic deformation of nanotwinned polycrystalline copper through large-scale molecular dynamics simulations. The simulations show that plastic deformation is initiated by partial dislocation nucleation at grain boundary triple junctions. Both pure screw and 60o dislocations cutting across twin boundaries and dislocation-induced twin boundary migration are observed in the simulation. Following twin boundary cutting, 60o dislocations frequently cross-slip onto {0 0 1} planes in twin grains and form Lomer dislocations. We further examine the effect of twin spacing on this Lomer dislocation mechanism through a series of specifically designed nanotwinned copper samples over a wide range of twin spacings. The simulations show that a transition in the deformation mechanism occurs at a small, critical twin spacing. While at large twin spacings, cross-slip and dissociation of the Lomer dislocations create dislocation locks that restrict and block dislocation motion and thus enhance strength, at twin spacings below the critical size, cross-slip does not occur, stepical size, cross-slip does not occur, steps on the twin boundaries form and deformation is much more planar. These twin steps can migrate and serve as dislocation nucleation sites, thus softening the material. Based on these mechanistic observations, a simple, analytical model for the critical twin spacing is proposed and the predicted critical twin spacing is shown to be in excellent agreement both with respect to the atomistic simulations and experimental observations. In addition, atomistic reaction pathway calculations show that the activation volume of this dislocation crossing twin boundary process is consistent with experimental values. This suggests that the dislocation mechanism transition reported here for the first time can be a source of the observed transition in nanotwinned copper strength.
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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.)
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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
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/
Plasma resistivity measurements in the Wisconsin levitated octupole
Energy Technology Data Exchange (ETDEWEB)
Brouchous, D. A.
1980-11-01
Resistivity measurements parallel to the magnetic field were made on gun injected plasmas ranging in density from 10/sup 9/cm/sup -3/ to 10/sup 1/parallelcm/sup -3/ in the Wisconsin levitated octupole with toroidal and poloidal magnetic fields. The 10/sup 9/cm/sup -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 = ..sqrt..T/sub e//n/sub e/ when E/sub parallel/ > E/su c/ is the Dreicer critical field. The 10/sup 12/cm/sup -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/.
Electric octupole contribution to the angular distribution of the krypton 4p photoelectrons
Holste, K.; Borovik, A. A., Jr.; Buhr, T.; Ricz, S.; Kövér, Á.; Bernhardt, D.; Schippers, S.; Varga, D.; Müller, A.
2014-04-01
The angular distribution of Kr 4p photoelectrons was measured with linearly polarized synchrotron radiation in the function of the photon energy. The shape of the measured angular distributions indicates the presence of octupol interaction.
Maclean, E H; Persson, T; Tomas, R; Wenninger, J
2013-01-01
During the 2012 LHC run several observations were made of shifts to tune, coupling and chromaticity which were correlated with changes in the powering of Landau octupoles. Understanding the chromaticity dependence is of particular importance given its influence on instabilities. This note briefly summarizes the observations and describes our understanding to-date of the relationship between Q, Q?, |C?| and the Landau octupole powering.
Improvement of LHC dynamic aperture via octupole spool pieces for the nominal tunes
Jin, L; Schmidt, F
1998-01-01
The dynamic aperture of the LHC optics version 5 at injection energy has been calculated for an opti-mistic error table, the so called target error table, in which erect and/or skew octupolar components were increased up to values close to realistic estimates. Correction strategies, using octupole spool pieces or the lattice octupoles, have been tested so as to recover, as much as possible, the loss in dynamic aperture.
Mixed-symmetry octupole and hexadecapole excitations in the N=52 isotones
Hennig, A.; Spieker, M.; 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
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-scat...
Properties of $2\\times 2$ h-deformed quantum (super)matrices
Yun LI; Jing, Sicong
2003-01-01
We investigate the $h$-deformed quantum (super)group of $2\\times 2$ matrices and use a kind of contraction procedure to prove that the $n$-th power of this deformed quantum (super)matrix is quantum (super)matrix with the deformation parameter $nh$.
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This paper presents an experimental study on dynamic compressive properties of rigid urethane foams under high deformation velocities realized by means of an impulsive shock device. Two kind of rigid foams are studied within the impulse range: 500 pa. s to 1.200 pa.s. Experimental results are analysed and a comparison between static and dynamic behaviour is made
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.
An extended deformation model of 24Mg
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A quadrupole- and octupole-deformed field is realized in the K sup(?) = 0+-, 2+, 3- rotational bands of 24Mg. The K sup(?) = 0+- bands make the inversion doublet with the lowest configuration. the K sup(?) = 2+ and 3- bands are built upon their respective single 1p-1h configurations. The deformed-shell character dominates in the low-lying states of 24Mg, particularly in the K sup(?) = 0+, 2+, 3- bands. The effects of the one-body and two-body spin-orbit forces are discussed. (author)
International Nuclear Information System (INIS)
Ratio of the subgrain boundary dislocations to those contributing to creep deformation was found to be independent of applied stress and creep strain after the steady-state creep stage is reached. The observed cell or subgrain sizes are correlated with flow stress in Type 304 ss, and the deformation rate-stress relation obeys the equation epsilon =? lambda3 (sigma/sub T//E)/sub n/ exp (-Q/sub c//RT), where lambda = subgrain size, sigma/sub T/ = effective true stress, E = Young modulus, and Q/sub c/ = 85 kcal/mole. Well-developed subgrains were observed in TEM on 304 ss tested in creep at 7040C. Role of twin boundary-grain boundary intersections in microcracking behavior of 304 ss deformed in slow tension and creep at 6500C was investigated. Grain shape analysis show that intragranular deformation becomes more predominant in the grains with the larger intercept distances, and that grain boundary sliding becomes important as the strain rate decreases. RT mechanical properties of austenitic ss are enhanced by subgrains formed during high-temperature deformation. The substructural development during high-temperature low-cycle fatigue of 304 ss was studied using TEM. Fatigue properties of Incoloy 800 tested in bend and push-pull modes are being compared. Effects of hold time on fatigue substructure and fracture of 304 ss are being studied. 31 figures, 53 references
Boakye-Yiadom, Solomon; Khan, Abdul Khaliq; Bassim, Nabil
2014-11-01
Impacting hardenable steel such as 4340, results in the formation of adiabatic shear bands (ASBs). Previous studies have shown that the presence of carbides/second-phase particles in the pre-deformation microstructures of 4340 steel increases their susceptibility to the formation of ASBs. The current study examines the role of carbides on the microstructure and properties within evolved ASBs in 4340 steel after impact. Geometric phase analysis was used to map local deformation fields within the evolved ASBs. It was observed that carbide fragmentation due to plastic deformation of carbides produces both residual carbides and residual carbide particles in regions away from the shear bands. Extensive carbide fragmentation produces fine residual carbide particles which are redistributed within the ASBs. This is attributed to strain localization within the ASBs which result in higher local strain and strain rates within the shear bands than in regions outside the bands. In addition, it is observed that the residual carbide particles trap and pin dislocations within the shear bands and contribute to an increase in local hardening. A more homogenous distribution of narrower and shorter rotational and shear-strain fields were revealed by the local deformation maps within the evolved ASBs. Lattice deformation mapping revealed that the ferrite matrix, prior to impact, had broader and longer rotational and shear-strain fields perpendicular to the direction of impact. This is attributed to lattice-invariant deformation and shape deformation processes that occur on specific crystallographic planes during martensitic transformation. It is concluded that strain localization during high strain rate deformations does not occur on specific crystallographic planes. This results in a more regular distribution of internal lattice rotational and strain fields within the evolved ASBs.
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
Phase stability, deformation mechanisms, and mechanical properties of Nb-Al-Ti alloys
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The phase stability, deformation mechanisms and mechanical properties of two alloys based on Nb3Al containing additions of Ti have been studied. These two alloys, with nominal compositions (in at.%) of Nb-15Al-10Ti (alloy 1) and Nb-15Al-40Ti (alloy 2), have the B2 crystal structure in as cast form. The ALCHEMI technique has been employed to assess qualitatively the distribution of atom types over the two sublattices of the B2 compounds. It is found that Ti and Al occupy different sublattices in alloy 2. Heat-treatment of alloy 1 at 1,100 C results in the precipitation of an A15 phase in the B2 matrix. Annealing at 900 C for short time introduces an w-phase. Prolonged annealing of alloy 1 at 700 C reveals the presence of an orthorhombic phase. The same orthorhombic phase is also found to exist between 800 and 1,000 C in alloy 2. Specific orientation relationships exist between the matrix phase and precipitates. The yield strength in compression of Alloy 1 and 2 were determined at various temperatures. Alloy 1 is strong compared to superalloy IN 718 over a range of temperatures up to 950 C. Both alloys with the B2 crystal structure are deformed by one or more of the following slip systems, namely (110), (112) and (123). Dislocations with Burgers vector, b, given by b= are present in the form of dissociated superpartial pairs, each with b=1/2. The inherent ductility of both alloys is indicated by the active slip systems and illustratedby the active slip systems and illustrated by 20% elongation to failure obtained in alloy 2 under room temperature tensile test. A trend of increasing tensile yield stress with increasing antiphase domain size was found. No evidence of interaction between dislocations and antiphase boundaries has been found to account for this increase of strength
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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
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.
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.
Effect of cold deformation on structure and properties of aluminium alloy 1441 sheets
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The influence of tensile deformation on the 1441 alloy (Al-Cu-Mg-Li-Zr) in four states: quenched; quenched, straightened and naturally aged; annealed; quenched, straightened and artificially aged one, has been studied. It has been ascertained that deformation after quenching results in a considerable growth of yield strength. Artificial aging makes an insignificant contribution to stregthening of deformed sheet. 2 refs.; 4 figs
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.
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.
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This paper investigated the effect of high-rate deformation on the change of mechanical properties on the surface of metallic materials during a peening as a surface modification of metallic materials. Especially, we focused on the introduced compressive residual stress and the yield stress increase on the surface, which brings about the improvement of fatigue strength of the materials after peening. For this purpose, we compared the results using two different peening. One is a static indentation with a steel ball, and the other is a dynamic peening with high velocity. The residual stresses were obtained through the comparison with experimental depths using an elastic-viscoplastic finite element model for the peening, and the variation in yield stress was also obtained using indentation tests and numerical analysis of indentation tests. As a result, we clarified the effect of strain-rate on the variation in yield stress and induced residual stress. Especially, the compressive residual stress and the increments of yield stress of the surface layer within 600?m depth after dynamic peening was larger than that after static peening. (author)
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.
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+.
High power ICRH experiments on the Wisconsin levitated octupole
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Preliminary ICRH experiments have begun on the Wisconsin Levitated Octupole. In order to study heating, energy confinement, and high ? plasmas, a 1.8 to 3 MHz oscillator and antenna have been installed. The oscillator and antenna have been installed. The oscillator is capable of delivering 2 MW of RF power for 10 msec, and to date up to 0.5 MW has been coupled into the plasma. At a density of approx. 6 x 1012 cm-3, T/sub e/ reaches a maximum of 30 eV as measured by Langmuir probes and VUV spectroscopy. Charge exchange measurements of T/sub i/ show Maxwellian components at 95 and 190 eV, with an energy confinement time of approx. 1 msec. Electron energy confinement is limited by impurity radiation, and several methods of impurity control are being tested. Current experiments also include direct measurement of the RF electric field, antenna loading measurements, variation of the oscillator frequency, and ohmic heating of the electrons
Influence of sensitizing additives on deformation-strength properties of radiation vulcanized rubber
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Full text: Expanding the practical use of products of radiation-vulcanized elastopolymers (RVEP) makes it necessary to increase their operational properties. Applied to the exploitation of polymers in the field of the ionizing radiation does not always meet shown requirements to them. In the present report the influence of sensitizer of disulpho chloride aromatic compounds on deformation-strength and their ageing under the influence of radiation exposure is being examined. The serial produced aromatic compounds of disulpho chloride bezene (DSCB) were used as sensitizers. It is established that, during the sensitization of radiation chemical vulcanization the mixture of butadiene-nitrile rubber with PVC with other ingredients affect the density of the spatial grid which determines the mechanical properties of vulcanized rubber. Two processes simultaneously run in the presence of sensitizing additives: inhibition of radiation oxidation which causes cross-linking and formation of the spatial grid in BNC. The role of sensitizer in the process of radiation vulcanization is defined first of all by reducing the doze of irradiation in the vulcanization process; simultaneously accelerate the cross-linking of the polymer chains. On the base of physical mechanical and structure of DSCB, can be judged that the influence of ionizing radiation leads the polar groups to ionization besides, their excited potential during ionization is very high which provides material with radiation gh which provides material with radiation resistance. Considering the resistance of DSCB to radiation, its practical value is high and can conduct vulcanization at low doses (150-300 kGy). (authors)
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A systematic analysis of microhardness variation is performed to study structural-mechanical heterogeneity in 14-layer titanium-steel (titanium VT1-0 + steel 08kp) composite specimens, produced by explosion welding with subsequent rolling at 700 deg C. The specimens studied are subjected to bending under a symmetrical three-point loading. Substantial changes in microhardness are revealed depending on the value and the sign of deformation. Tensile deformation of 15-17 % gives rise to partial softening of both titanium and steel layers. In a range of 1-2 % of compressive load deformation the steel layers are softened. At deformation above 4 % the steel is prone to hardening. In the titanium layers the microhardness monotonically increases with deformation
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...
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Research highlights: ? Fine ? hindered dislocation slip and crack nucleation and decreased crack propagation velocity. ? ? lamellae decided the type and amount of slip system and the crack propagation. ? Fine ? lamellae promoted the deformation coordination and the start of new slip systems. ? The fracture model of the samples with bimodal microstructure was not sensitive to ? lamellae. ? Fracture model with the bimodal microstructures was a mixture fracture at room temperature. - Abstract: The tensile properties at room temperature and 600 deg. C of TG6 titanium alloy with different microstructures {bi-modal microstructures with thick ? lamella (BTL) and fine ? lamella (BFL), and a mixed microstructure with different morphologies of ? phase} were obtained. It was found that the BFL microstructure possessed the highest tensile strength, and the elongations of the BTL and BFL microstructures were almost the same of about 13% at room temperature and 17% at 600 deg. C, respectively. In addition, the mixed microstructure had the lowest plasticity. The tensile deformation mechanisms of ? lamella (?L), primary ? phase (?p), equiaxed ? phase (?e) and ? colonies were researched by the analysis of respective dislocation morphologies. Notably, the accommodative deformations through grain/phase boundaries sliding determined the deformation models of ?L, ?p, and ?e. Compared to the thick d to the thick ?L and ? colony, the fine ?L and ? colony activated more slip systems due to their excellent accommodative deformation capability. Furthermore the deformation mechanisms at room temperature and 600 deg. C were different from each other. Scanning electron microscope (SEM), energy-dispersive spectrometer (EDS) and transmission electron microscopy (TEM) were used to research the crack propagation paths and fracture models. Crack propagation path crossing ? colonies and ?p were discussed, respectively. The colonies boundaries, ?p/colonies boundaries, ?e/?e boundaries and silicide were found to be the stress concentration locations. The micro-plasticity of tensile specimens determined the fracture morphologies and fracture models.
Structural changes and properties of molybdenum upon cold and cryogenic deformation under pressure
Gapontseva, T. M.; Pilyugin, V. P.; Degtyarev, M. V.; Voronova, L. M.; Chashchukhina, T. I.; Patselov, A. M.
2014-10-01
The structure and hardness of a molybdenum single crystal with an (110) orientation, which was deformed by high pressure torsion at 290 and 80 K, are investigated. Such deformation mechanism as dislocation slip that is characteristic of materials with a high stacking fault energy works also during cryogenic deformation: twinning does not occur. At both temperatures, the single crystal transforms into a polycrystalline state at a true strain e ? 2. Up to the maximum achievable true strains, no uniform-in-size submicrocrystalline structure forms in molybdenum.
Accretion onto Stars with Octupole Magnetic Fields: Matter Flow, Hot Spots and Phase Shifts
Long, Min; Lamb, Frederick K
2009-01-01
Recent measurements of the surface magnetic fields of classical T Tauri stars (CTTSs) and magnetic cataclysmic variables show that their magnetic fields have a complex structure. The magnetic field associated with the octupole moment may dominate the magnetic field associated with other moments in some stars, such as the CTTS V2129 Oph. Previously, we studied disc accretion onto stars with magnetic fields described by a superposition of aligned or misaligned dipole and quadrupole moments. In this paper, we present results of the first simulations of disc accretion onto stars with an \\textit {octupole} field. As examples, we consider stars with a superposition of octupole and dipole fields of different strengths and investigate matter flow around them, the shapes of hot spots on their surfaces, and the light curves produced by their rotation. We investigate two possible mechanisms for producing phase shifts in the light curves of stars with complex fields: (1) change of the star's intrinsic magnetic field and ...
Thermo-mechanical properties of a deformable mirror with screen printed actuator
Bruchmann, C.; Appelfelder, M.; Beckert, E.; Eberhardt, R.; Tünnermann, A.
2012-03-01
This paper reports on the thermo-mechanical modeling and characterization of a screen printed deformable mirror. The unimorph mirror offers a ceramic LTCC substrate with screen printed PZT layers on its rear surface and a machined copper layer on its front surface. We present the thermo-mechanical model of the deformable mirror based on Ansys multiphysics. The developed mirror design is practically characterized. The homogeneous loading of the optimized design results in a membrane deformation with a rate of -0.2 ?m/K, while a laser loading causes a change with a rate of 1.3 ?m/W. The proposed mirror design is also suitable to pre-compensate laser generated mirror deformations by homogeneous thermal loading (heating). We experimentally show that a 35 K pre-heating of the mirror assembly could compensate an absorbed laser power of 1.25 W.
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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
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.
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Deformed microstructure and mechanical properties of AM60B magnesium alloy under hypervelocity impact at a speed of 4 km s-1 were studied through optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and indenter technique. The results show that the deformed microstructure below the crater can be classified as three zones, i.e. dynamic recrystallization zone, high density deformation twin zone and low density deformation twin zone. The refined and equiaxed recrystallized grains adjacent to the crater were formed, which should be attributed to the twining-induced dynamic recrystallization mechanism. The {101-bar 2}, {101-bar 1} deformation twins are confirmed through selected area electron diffraction (SAED) technique. The microhardness and yield strength in the deformed microstructure zone near the crater are much higher than that of the matrix, which should be attributed to strain hardening and grain refining.
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Axial and non-axial octupole excitations built on superdeformed states of zero spin in 192,194Hg and 194Pb nuclei are studied within the fully microscopic generator-coordinate method using selfconsistent Hartree-Fock BCS states as a basis. Results with the effective interaction SkM* predict vibration energies of 1.9-2.5 MeV, B(E3) values of 15-37 single-particle units and unusually large B(E1) transition rates up to 0.02 W.u. Calculations including both octupole modes with K=0 and K=2 indicate that these modes couple weakly. (orig.)
Specifications of the octupole magnets required for the ATF2 ultra-low ß* lattice
Energy Technology Data Exchange (ETDEWEB)
Marin, E.; /SLAC; Modena, M.; /CERN; Tauchi, T.; Terunuma, N.; /KEK, Tsukuba; Tomas, R.; /CERN; White, G.R.; /SLAC
2014-05-28
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 ß* 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.
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Highlights: ? Precipitation of Ni4Ti3 during aging at 450 °C is hindered after severe cold work. ? Nanostructure formation improves the superelastic behavior of Ni-rich NiTi. ? Deformations less than 0.4 result in work hardening and reduce plateau strain. ? Deformations more than 0.4 yield in high stress and strain values of upper plateau. -- Abstract: Superelastic properties of Ni50.9Ti shape memory wires were studied after cold drawing and post-deformation annealing at 450 °C. Characteristic transformation temperatures were determined using differential scanning calorimetry. Microstructural investigations were performed using optical and transmission electron microscopy. Results indicate that deformations more than 0.4 of true strain yield in high stress and high strain values of upper plateau. On the other hand, deformations less than 0.4 result in work hardening and reduce plateau strain. Post-deformation heat treatment at 450 °C leads to precipitation of Ni4Ti3 particles and development of recovered microstructure in slightly cold drawn wires. Post-deformation annealing of wires with cold work value of 0.6 in true strain develop nanocrystalline microstructure and hindered the formation of Ni4Ti3 precipitates. Precipitation of Ni4Ti3 particles improves the superelastic properties of not cold drawn wires. However, in comparison with annealed and aged wires, severely deformed wires attain better superelastic properties after annealing at 450 °C without any Ni4Ti3 precipitates
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Hyperfine structures and isotope shifts of sup(207-213,220-228)Fr have been measured by high-resolution laser spectroscopy. Nuclear moments and changes in the mean-square charge radii are deduced. They are compared with analogous data for radium and discussed in terms of the octupole deformation mode. (orig.)
Deformation and energy absorption properties of powder-metallurgy produced Al foams
International Nuclear Information System (INIS)
Highlights: ? Porous Al fabricated via a dissolution and sintering method using raw cane sugar. ? Different deformation mode depending on the relative density of the foams. ? Enhanced energy absorption by reducing pore size and relative density of the foam. ? Pore size uniformity and sintering temperature affect energy absorption. - Abstract: Al-foams with relative densities ranging from 0.30 to 0.60 and mean pore sizes of 0.35, 0.70 and 1.35 mm were manufactured by a powder metallurgy technology, based on raw cane sugar as a space-holder material. Compressive tests were carried out to investigate the deformation and energy absorbing characteristics and mechanisms of the produced Al-foams. The deformation mode of low density Al-foams is dominated by the bending and buckling of cell walls and the formation of macroscopic deformation bands whereas that of high density Al-foams is predominantly attributed to plastic yielding. The energy absorbing capacity of Al-foams rises for increased relative density and compressive strength. The sintering temperature of Al-foams having similar relative densities has a marked influence on both, energy absorbing efficiency and capacity. Pore size has a marginal effect on energy efficiency aside from Al-foams with mean pore size of 0.35 which exhibit enhanced energy absorption as a result of increased friction during deformation at lower strain levels.
Properties of heterogeneous energetic materials under high strain, high strain rate deformation
Cai, Jing
Heterogeneous energetic materials have many applications. Their dynamic behavior and microstructural evolution upon plastic deformation have remained not fully understood. The following heterogeneous materials were investigated in the this study: the pure PTFE (usually a mixture of crystalline and amorphous phases), PTFE-Sn, PTFE-Al, PTFE-Al-W, and carbon fibers filled Al alloy. Sample manufacturing processes involving ball milling and Cold Isostatic Pressing were employed. Quasi-static and Hopkinson bar tests were carried out to obtain the compressive strengths of composites. The Conventional Thick-walled Cylinder (TWC) method and newly developed small-scale Hopkinson bar based TWC experiments were conducted to investigate single shear bands and their assembly. Conventional and "soft" drop-weight tests were performed to examine the mechanical properties and the initiation of chemical reactions. Scanning Electron Microscopy was used to detect the details of the microstructures and failure mechanisms of heterogeneous materials. New features in the dynamic behavior of heterogeneous materials were observed. They include the following: (1) Strain softening, instead of thermal softening, is the main mechanism in the initiation of shear bands in explosively driven TWC tests of solid PTFE. (2) Cold isostatically pressed PTFE-Sn samples were more stable with respect to shear localization than solid PTFE. (3) The dynamic collapse of solid PTFE-Al samples with different particle sizes was accomplished with the shear localization bands and cracks. (4) Force chains in the fine W and Al particles were attributed to the high strength of the porous PTFE-Al-W composite containing fine W particles in comparison with composites with coarse W particles. (5) Debonding of metal particles from the PTFE matrix and the fracture of the matrix were identified to be two major mechanisms for the failure of the PTFE-Al-W composites. (6) The formation of PTFE nano-fibers during high strain flow was detected. (7) The orientation of carbon fibers did not influence the strength and reaction of carbon fibers filled Al alloys, but the strength of carbon fibers did.
International Nuclear Information System (INIS)
In this paper, we introduce two new classes of nonlinear squeezed states that we name as f-deformed squeezed vacuum state |?, f?even and f-deformed squeezed first excited state |?, f?odd, which according to their production processes, essentially include only even and odd bases of Fock space, respectively. In the continuation, we introduce the superposition of these two distinct nonlinear squeezed states with a respective phase ?. Then, some of the criteria which imply the nonclassicality of the states, such as Mandel parameter, second-order correlation function, quadrature squeezing, amplitude-squared squeezing, Husimi and Wigner–Weyl quasi-distribution functions, are numerically examined. At last, by considering a well-known nonlinearity function associated with a nonlinear physical system, we present our results which outcome from the numerical calculations. It is shown that, the introduced f-deformed states can reveal high nonclassical features
New level schemes and octupole correlations of light neutron-rich lanthanum isotopes 143,144La
International Nuclear Information System (INIS)
The yrast and near-yrast level scheme of light neutron-rich 143La (Z=57, N=86) is reinvestigated and expanded and that of 144La (N=87) is proposed for the first time by measuring prompt ? rays from the spontaneous fission of 252Cf at Gammasphere. Spins/parities are assigned to the lowest-lying levels of 143,144La based on the early studies of ?- decay, and the assignments for high-spin levels of 143,144La are made by measuring internal conversion coefficients and following the level systematics of the neighboring heavier La isotopes and even-even Ba and Ce nuclei. The B(E1)/B(E2) ratios, energy displacements ?E(I) and rotational frequency ratios ?-(I)/?+(I) of the new parity-doublets of 143,144La indicate that octupole deformations/correlations also develop in these nuclei. The band-crossings observed in a rotational frequency range of 0.31 to 0.34 MeV for the two even-parity bands in 143La but being absent in 144La are interpreted as due to alignment of a pair of i13/2 neutrons in 143La
On supersymmetry and other properties of a class of marginally deformed backgrounds
International Nuclear Information System (INIS)
We summarize our recent work on supergravity backgrounds dual to part of the Coulomb branch of N=1 theories constructed as marginal deformations of N=4 Yang-Mills. In particular, we present a summary of the behaviour of the heavy quark-antiquark potential which shows confining behaviour in the IR as well as of the spectrum of the wave equation. The reduced supersymmetry is due to the implementation of T-duality in the construction of the deformed supergravity solutions. As a new result we analyze and explicitly solve the Killing spinor equations of the N=1 background in the superconformal limit. (Abstract Copyright [2006], Wiley Periodicals, Inc.)
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
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
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.
International Nuclear Information System (INIS)
The methods are compared of electroslag welding and of arc welding with a view to their possible application in welding the Bohunice A-1 reactor pressure vessel. Considered are the thermal deformation effects of welding on the physical properties and the stress present in welded joints. For testing, plates were used having the dimensions of 1100x2300x200 mm and rings with 4820 mm outer diameter, 1800 mm height and 170 mm thickness made of steel CSN 413O30 modified with Ni, Al+Ti. The deformation effect of welding on the residual surface and triaxial stress, the specific stored energy, the initiation temperature of brittle crack and the critical size of the initiation defect corresponding to the thermal deformation effect of welding were determined. It was found that for electroslag welding, there is a low probability of crack formation in the joints, a low level of residual stress and a low level of specific stored energy in a relatively wide joint zone. For arc welding there is a considerable probability of defect formation in the vicinity of the sharp boundary of the joint, a high level of the triaxial state of stress in the tensile region, and a high level of specific stored energy concentrated in the narrow zone of weld joints. The recommended thermal process is given for welding pressure vessels made of the CSN 413030 steel modified with Ni, Al+Ti, and 150 to 200 mm in thickness. (J.P.)
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Wang Tao, E-mail: wangtao8206@163.com [School of Material Science and Engineering, Northwestern Polytechnical University, 127 West Youyi Road, Xi' an 710072 (China); Guo Hongzhen; Wang Yanwei; Peng Xiaona; Zhao Yan; Yao Zekun [School of Material Science and Engineering, Northwestern Polytechnical University, 127 West Youyi Road, Xi' an 710072 (China)
2011-03-15
Research highlights: {yields} Fine {alpha} hindered dislocation slip and crack nucleation and decreased crack propagation velocity. {yields} {alpha} lamellae decided the type and amount of slip system and the crack propagation. {yields} Fine {alpha} lamellae promoted the deformation coordination and the start of new slip systems. {yields} The fracture model of the samples with bimodal microstructure was not sensitive to {alpha} lamellae. {yields} Fracture model with the bimodal microstructures was a mixture fracture at room temperature. - Abstract: The tensile properties at room temperature and 600 deg. C of TG6 titanium alloy with different microstructures {l_brace}bi-modal microstructures with thick {alpha} lamella (BTL) and fine {alpha} lamella (BFL), and a mixed microstructure with different morphologies of {alpha} phase{r_brace} were obtained. It was found that the BFL microstructure possessed the highest tensile strength, and the elongations of the BTL and BFL microstructures were almost the same of about 13% at room temperature and 17% at 600 deg. C, respectively. In addition, the mixed microstructure had the lowest plasticity. The tensile deformation mechanisms of {alpha} lamella ({alpha}{sub L}), primary {alpha} phase ({alpha}{sub p}), equiaxed {alpha} phase ({alpha}{sub e}) and {alpha} colonies were researched by the analysis of respective dislocation morphologies. Notably, the accommodative deformations through grain/phase boundaries sliding determined the deformation models of {alpha}{sub L}, {alpha}{sub p}, and {alpha}{sub e}. Compared to the thick {alpha}{sub L} and {alpha} colony, the fine {alpha}{sub L} and {alpha} colony activated more slip systems due to their excellent accommodative deformation capability. Furthermore the deformation mechanisms at room temperature and 600 deg. C were different from each other. Scanning electron microscope (SEM), energy-dispersive spectrometer (EDS) and transmission electron microscopy (TEM) were used to research the crack propagation paths and fracture models. Crack propagation path crossing {alpha} colonies and {alpha}{sub p} were discussed, respectively. The colonies boundaries, {alpha}{sub p}/colonies boundaries, {alpha}{sub e}/{alpha}{sub e} boundaries and silicide were found to be the stress concentration locations. The micro-plasticity of tensile specimens determined the fracture morphologies and fracture models.
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...
Grydin, O.; Stolbchenko, M.; Nürnberger, F.; Schaper, M.
2014-03-01
Thin strips of medium- and high-strength age-hardening aluminium alloys are widely used in the automotive industry. Reducing their production costs caused by high energy consumption is an actual challenge. The implementation of the twin-roll casting technology is promising. However, mechanical properties of directly cast high-alloyed thin aluminium strips are oftentimes inadequate to standard specifications. In this work, the influence of a hot deformation following a twin-roll cast strip process on the mechanical properties and microstructure is investigated. For this study strips of age-hardening aluminium alloy EN AW-6082—manufactured at a laboratory scaled twin-roll caster—were single-pass rolled at temperatures of 420 °C and true strains of up to 0.5. The mechanical properties of the as-cast and by different strains hot deformed material in the soft-annealed and age-hardened states were characterized by tensile tests. The results reveal that the twin-roll cast material features the necessary strength properties, though it does not meet the standard requirements for ductility. Furthermore, the required minimum strain during hot rolling that is necessary to ascertain the standard specifications has been determined. Based on micrographs, the uniformity of the mechanical properties and of the microstructure as a result of recrystallization due to hot metal forming and heat treatment were determined. A fine-grain microstructure and satisfactory material ductility after prior rolling with a true strain above 0.41 for the age-hardened state T6 and above 0.1 for the soft-annealed state O have been established.
International Nuclear Information System (INIS)
Mechanical and thermal properties of invar 20N34K5F are studied after various heat and thermomechanical treatments including plastic deformation and carbide aging. The mechanical properties obtained are compared with analogous ones for invar N36K10T3 hardened in aging by dispersed intermetallics. Invars 20N34K5F and N36K10T3 have practically the same thermal properties. It is shown that three hardening treatments result in a higher strength for the last material. The one exception is a more high growth of ultimate strength and yield strength in alloy 20N34K5 due to cold plastic deformation
Belyakov, A.; Odnobokova, M.; Kipelova, A.; Tsuzaki, K.; Kaibyshev, R.
2014-08-01
The development of nanocrystalline structures in austenitic stainless steels during large strain cold rolling and their tensile behavior were studied. The cold rolling to total equivalent strains above 2 was accompanied by the evolution of nanocrystalline structures with the transverse grain size of about 100 nm. The development of deformation twinning and martensitic transformation during cold working promoted the fast kinetics of structural changes. The development of nanocrystalline structures resulted in significant strengthening. More than fourfold increase in the yield strength was achieved. The strengthening of nanocrystalline steels after severe plastic deformation was considered as a concurrent operation of two strengthening mechanisms, which were attributed to grain size and internal stress. The contribution of internal stresses to the yield strength is comparable with that from grain size strengthening.
Effect of vacuum-treatment on deformation properties of PMMA bone cement.
Zivic, Fatima; Babic, Miroslav; Grujovic, Nenad; Mitrovic, Slobodan; Favaro, Gregory; Caunii, Mihaela
2012-01-01
Deformation behavior of polymethyl methacrylate (PMMA) bone cement is explored using microindentation. Two types of PMMA bone cement were prepared. Vacuum treated samples were subjected to the degassing of the material under vacuum of 270 mbar for 35 s, followed by the second degassing under vacuum of 255 mbar for 35 s. Air-cured samples were left in ambient air to cool down and harden. All samples were left to age for 6 months before the test. The samples were then subjected to the indentation fatigue test mode, using sharp Vickers indenter. First, loading segment rise time was varied in order to establish time-dependent behavior of the samples. Experimental data showed that viscous part of the deformation can be neglected under the observed test conditions. The second series of microindentation tests were realized with variation of number of cycles and indentation hardness and modulus were obtained. Approximate hardness was also calculated using analysis of residual impression area. Porosity characteristics were analyzed using CellC software. Scanning electron microscopy (SEM) analysis showed that air-cured bone cement exhibited significant number of large voids made of aggregated PMMA beads accompanied by particles of the radiopaque agent, while vacuum treated samples had homogeneous structure. Air-cured samples exhibited variable hardness and elasticity modulus throughout the material. They also had lower hardness values (approximately 65-100 MPa) than the vacuum treated cement (approximately 170 MPa). Porosity of 5.1% was obtained for vacuum treated cement and 16.8% for air-cured cement. Extensive plastic deformation, microcracks and craze whitening were produced during indentation of air-cured bone cement, whereas vacuum treated cement exhibited no cracks and no plastic deformation. PMID:22100087
Yurkova A.I.; Byakova A.V.
2012-01-01
By using nanoindentation technique relationship between microstructure and mechanical parameters such as nanohardness Hh, plasticity characteristic A, and Young’s modulus E were found to be dependent on the grain size of the -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...
Antonova, O. V.; Novikova, O. S.; Antonov, B. D.; Volkov, A. Yu.
2015-04-01
The possibility of severe plastic deformation of the Cu-47Pd (at %) alloy by room temperature rolling to high degrees without intermediate anneals has been shown. The microstructure and physicomechanical properties of ribbons 100 and 4.5 ?m thick in the initial strongly deformed state (the true degree of deformation ? ? 4.4 and ? ? 7.5, respectively), as well as after thermal treatments of various durations have been studied. High alloy plasticity during rolling is explained by recovery processes, which occur in the material during SPD. The formation of single-phase B2-type ordered state, which diverges with the phase diagram, is found.
International Nuclear Information System (INIS)
A study is made into the effect of decomposition of deformed supersaturated solid solution on hardness, electric conductivity, magnetic susceptibility and linear thermal expansion in N30K10T3 invar on aging. It is shown that cold plastic deformation increases hardness by 30-50 %, has no effect on electric conductivity and decreases magnetic susceptibility of the material. Deformed invar has low value of thermal expansion coefficient at the room temperature but it increases with aging temperature. Phase studies revealed a number of crystal-phase transformations in the invar under strain aging which are responsible for variations of physical and mechanical properties
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.
International Nuclear Information System (INIS)
The time-dependent phenomena which can affect the strength and deformation properties of hard crystal line rock are clarified. Suitable measuring methods for field conditions are also summarized. The significance of time is evaluated around a shaft in a high level nuclear waste repository. According to the investigation it is generally held that creep and cyclic fatigue are the most important phenomena. They arise from subcritical crack growth which is most affected by stress intensity, chemical environment, temperature, and microstructure. There are many theoretical models, which can be used to analyse creep and cyclic fatigue, but they are defective in describing the triaxial stress condition and strength criteria. Additionally, the required parameters are often too difficult to determine with adequate accuracy. The joint creep rate depends on the affecting stress regime, on the water conditions, and on the properties of filling material. The acoustic emission method is suited to observe long-term microcrack development in field conditions. The computer program developed by Atomic Energy of Canada Limited (AECL) is used to evaluate the time-dependent de-formation around a main shaft. According to the model the enlargement of the shaft radius by 30 cm takes millions of years. The possible reduction of shaft radius by 3 mm will happen during 200 years. The model is very sensitive to changes in stress state, in the uniaxial compressive strength, and in the stress corrosion index
Theory and measurement of properties of two-phase materials in the plastic-viscous deformation range
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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)
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The effect of tsub(A) austenitization temperature in heating for quenching as well as in the cycle of high-temperature thermomechanical treatment (HTMT) on structure, mechanical properties and fracture mode of 40KhN2MA structural steel is investigated. It is shown that heating up to 1200 deg C does not affect essentially ?sub(b) and ?sub(0.2) of a quenched material but increases fracture toughness of 200 deg C - tempered precracked specimens and is accompanied by a decrease of impact strength and plasticity of vee-notched specimens. The optimum complex of mechanical properties is attained upon combined treatment comprising heating up to 1200 deg C and HTMT with deformation at 850 deg C
Barmouz, Mohsen; Besharati Givi, Mohammad Kazem; Jafari, Jalal
2014-01-01
In this work, the tensile behavior of pure copper including ultimate tensile stress, yield stress, and elongation in the specimens friction stir processed under different processing parameters and pass adding was investigated in detail. The effect of strain hardening, grain refinement, and heat input on the tensile properties of these specimens was explained as well. It was observed that, regarding the aforementioned factors, the processing parameters and pass number could have considerable effects on the tensile deformation properties of the pure copper such as 300 and 47% enhancements in elongation and ultimate strength, respectively. It was demonstrated that higher passes resulted in the development of ultrafine grains (up to 700-800 nm) in the specimens. The fracture surface morphology was also used to further support the elongation results.
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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.)
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This paper presents a detailed characterization of the microstructural evolution of quenching and partitioning (Q and P) steel by dilatometer, X-ray diffraction and scanning electron microscopy. Influence of partitioning time on mechanical properties was investigated and the relationship between microstructures and mechanical properties was established. The results indicate that bainite transformation occurs at the preliminary stage of partitioning and the amount is proportional to quenching temperature. Martensite softening, bainite transformation kinetics, amount and stability of retained austenite collaboratively have effects on mechanical properties. The purpose of the EBSD investigation is to study the changes in the microstructure of the Q and P steel during deformation and obtain a better understanding of collaborative deformation-transformation behavior. During deformation, plastic deformation preferentially occurred in the vicinity of ferrite–martensite interfaces and spread to the interior of ferrite grain with strain increasing. Plastic deformation started to occur in martensite after large strain. Furthermore, grain rotation occurred in some austenite grains or divided into subgrains during deformation
Energy Technology Data Exchange (ETDEWEB)
Sun, Jing; Yu, Hao, E-mail: yhzhmr@126.com; Wang, Shaoyang; Fan, Yongfei
2014-02-24
This paper presents a detailed characterization of the microstructural evolution of quenching and partitioning (Q and P) steel by dilatometer, X-ray diffraction and scanning electron microscopy. Influence of partitioning time on mechanical properties was investigated and the relationship between microstructures and mechanical properties was established. The results indicate that bainite transformation occurs at the preliminary stage of partitioning and the amount is proportional to quenching temperature. Martensite softening, bainite transformation kinetics, amount and stability of retained austenite collaboratively have effects on mechanical properties. The purpose of the EBSD investigation is to study the changes in the microstructure of the Q and P steel during deformation and obtain a better understanding of collaborative deformation-transformation behavior. During deformation, plastic deformation preferentially occurred in the vicinity of ferrite–martensite interfaces and spread to the interior of ferrite grain with strain increasing. Plastic deformation started to occur in martensite after large strain. Furthermore, grain rotation occurred in some austenite grains or divided into subgrains during deformation.
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.)
Chaussard, E.; Burgmann, R.; Shirzaei, M.; Fielding, E. J.; Baker, B.
2014-12-01
Space geodesy has demonstrated its potential in detecting ground deformation associated with exploitation of aquifers. However, because geodetic data remain rarely integrated with hydrologic data, ground deformation observations are not typically used for water management purposes. Here, we characterize ground deformation of the Santa Clara Valley in the southern San Franciso Bay Area, an aquifer undergoing water extraction and recharge with over 50 multi-decadal monitoring wells. We perform Interferometric Synthetic Aperture Radar (InSAR) time-series analysis of ERS, Envisat, and ALOS SAR data to resolve the 1992-2011 ground deformation. Using T-mode Principal Component Analysis we isolate temporally and spatially variable deformation signals embedded in multi-decadal InSAR time series. The longer-term signal reveals uplift at 0.4 cm/yr between 1992-2000 and SCF). We integrate the deformation with hydraulic head data to characterize the aquifer-system properties at the scale of the basin, and show that after calibration we can accurately predict hydraulic head levels from deformation alone. Finally, by modeling the deformation partitioning across the SCF we constrain the time of the fault's last tectonic activity, hydraulic conductivity, and material composition. The SCF cuts the shallow confining clays and was last active since ~140 ka, it has a horizontal hydraulic conductivity several orders of magnitude lower than the surrounding aquifer system, and it is likely composed of clays, making it an effective barrier to across-fault fluid flow. Our results demonstrate that space-derived ground deformation, when combined with hydrological data, enables characterization of basin-wide aquifer-system and fault properties and could help characterize hydraulic heads in areas with sparse temporal well monitoring.
International Nuclear Information System (INIS)
A direct-chill (DC) cast magnesium alloys ZK60 has been forward-extruded at 300 deg. C in a single pass at two extrusion ratios (ER) 12 and 44, which correspond to a total degree of deformation (f) of 2.5 and 3.8, respectively. The as-extruded microstructure in both cases consists of two colonies of grain sizes, i.e. about 15 mu m and 25 mu m) at higher extrusion ratios give significantly weaker strength differential effect (difference in tensile yield stress and compressive yield stress). (author)
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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 anmod behavior of ductile and brittle fracture whereas incorporation of SiC particles and increasing the strain rate promoted ductile fracture mode.
Some deformation properties of the even–even ytterbium, hafnium and tungsten nuclei
International Nuclear Information System (INIS)
The deformation structure of the even–even ytterbium, hafnium and tungsten nuclei is investigated in framework of the collective model, the single-particle Schroedinger fluid model and the cranked Nilsson model. Accordingly, we have calculated the rotational and vibrational energies, the nuclear moments of inertia, the total ground-state energy, the quadrupole moment, the liquid drop (LD) energy, the Strutinsky inertia, the LD inertia, the volume conservation factor ?0/?0°, the smoothed energy, the Bardeen, Cooper and Schrieffer (BCS) energy and the G-value of the ytterbium: 170Yb, 172Yb and 174Yb, hafnium: 176Hf, 178Hf and 180Hf and tungsten: 182W, 184W and 186W nuclei as functions of the deformation parameters ?, ?, which are assumed to vary in the ranges (-0.50 ? ? ? 0.50) and (0° ? ? ? 60°). Also, two polynomials in ? are obtained to produce results in good agreement with the corresponding results for the total ground-state energy and the quadrupole moment of the mentioned nine nuclei. (author)
Some Deformation Properties of the Even-Even Ytterbium, Hafnium and Tungsten Nuclei
Doma, S. B.; El-Gendy, H. S.
2012-09-01
The deformation structure of the even-even ytterbium, hafnium and tungsten nuclei is investigated in framework of the collective model, the single-particle Schrödinger fluid model and the cranked Nilsson model. Accordingly, we have calculated the rotational and vibrational energies, the nuclear moments of inertia, the total ground-state energy, the quadrupole moment, the liquid drop (LD) energy, the Strutinsky inertia, the LD inertia, the volume conservation factor ? 0/? o_0, the smoothed energy, the Bardeen, Cooper and Schrieffer (BCS) energy and the G-value of the ytterbium: 170Yb, 172Yb and 174Yb, hafnium: 176Hf, 178Hf and 180Hf and tungsten: 182W, 184W and 186W nuclei as functions of the deformation parameters ?, ?, which are assumed to vary in the ranges (-0.50 ? ? ? 0.50) and (0° ? ? ? 60°). Also, two polynomials in ? are obtained to produce results in good agreement with the corresponding results for the total ground-state energy and the quadrupole moment of the mentioned nine nuclei.
Thermal Stability and Properties of Deformation-Processed Cu-Fe In Situ Composites
Liu, Keming; Jiang, Zhengyi; Zhao, Jingwei; Zou, Jin; Lu, Lei; Lu, Deping
2015-05-01
This paper investigated the thermal stability, tensile strength, and conductivity of deformation-processed Cu-14Fe in situ composites produced by thermo-mechanical processing. The thermal stability was analyzed using scanning electronic microscope and transmission electron microscope. The tensile strength and conductivity were evaluated using tensile-testing machine and micro-ohmmeter, respectively. The Fe fibers in the deformation-processed Cu-14Fe in situ composites undergo edge recession, longitudinal splitting, cylinderization, break-up, and spheroidization during the heat treatment. The Cu matrix experiences recovery, recrystallization, and precipitation phase transition. The tensile strength and conductivity first increase with increasing temperature of heat treatment, reach peak values at different temperatures, and then decrease at higher temperatures. The value of parameter Z of the in situ composite reaches the peak of 2.86 × 107 MPa2 pct IACS after isothermal heat treatment at 798 K (525 °C) for 1 hour. The obtained tensile strength and conductivity of the in situ composites are 907 MPa and 54.3 pct IACS; 868 MPa and 55.2 pct IACS; 810 MPa and 55.8 pct IACS; or 745 MPa and 57.4 pct IACS, at ? = 7.8 after isochronal heat treatment for 1 hour.
Cyclic deformation property and microstructure study of HT-9 ferritic steel at elevated temperatures
International Nuclear Information System (INIS)
In this study, cyclic deformation tests were carried out on HT-9 steel at room temperature, 300, 400, 500 and 600 C with a diametral strain range of ±0.5%, ±0.25% respectively. Transmission electron microscopy was presented to describe the micromechanisms of HT-9 steel under cyclic straining. The mechanical test results showed that cyclic softening behavior was observed at each testing temperature. The softening was attributed to the rearrangement of the high dislocation density structure into subgrain. In cyclically strained HT-9 specimens, carbides distributed along the subgrain boundaries. These carbides were considered to be the barriers against the subgrain to grow. The resistance of dislocation slip by carbides decreased to a less or extent at higher testing temperatures. The sharp subgrain boundaries observed in the specimens tested at higher temperatures showed a large decreasing rate in internal stress during cycling. HT-9 steel cyclically softened rapidly at testing temperatures higher than 500 C. In the case of HT-9 steel cyclically deformed at lower strain range, cyclic plastic strain was essentially accommodated by the ferrite region and strain cycling did not have obvious effects on the substructure of lath martensite. ((orig.))
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...
Antiferroquadrupole order and magnetic field induced octupole in CeB6
Matsumura, Takeshi; Yonemura, Takumi; Kunimori, Keisuke; Sera, Masafumi; Iga, Fumitoshi; Nagao, Tatsuya; Igarashi, Jun-ichi
2012-05-01
We have studied the antiferroquadrupole ordered phase of CeB6 in magnetic fields by resonant x-ray diffraction. By analyzing the significant change in the energy spectrum on reversing the field direction along [1¯10], we have deduced field dependencies of the antiferro components of magnetic dipole, electric quadrupole, and magnetic octupole moments which are simultaneously induced in the Ce 4f orbital with a propagation vector ((1)/(2),(1)/(2),(1)/(2)). The data treatments are based on theoretically calculated spectral functions. The existence of the field-induced octupole is also concluded for other field directions. We also show direct evidence for the formation of a linear-combination-type antiferroquadrupole order parameter in magnetic fields, which is expressed as and changes continuously with the field direction (?,?,?). A possibility of observing the quadrupolar fluctuation is also pointed out.
Octupole excitations in vibrational nuclei and the sdf interacting boson model
International Nuclear Information System (INIS)
Proton and deuteron inelastic scattering experiments, performed with an energy resolution of 12-15 keV, have been used to study negative-parity states of vibrational and transitional nuclei with mass between 98 and 150. The analysis has been focussed on the isovector components, on the quadrupole-octupole two-phonon states and on the fragmentation of the octupole strength. This latter displays a regular dependence on the product of proton and neutron valence particle numbers and is satisfactorily reproduced by IBM-1+f-boson calculations. Other features of the experimental spectra, as the relative positions of the 3- states, exhibit a dependence on the ratio of valence particle numbers and indicate that a IBM-2 approach might be more appropriate. (orig.)
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 predomina long-term use. This seems to be predominantly important in benign bronchial collapse
Progress Towards A Permanent Octupole Magnetic Ultra-Cold Neutron Trap for Lifetime Measurements
Leung, Kent; Zimmer, Oliver
2008-01-01
The current knowledge of the neutron $\\beta$-decay lifetime has come under scrutiny as of late due to large disagreements between recent precise measurements. Measurements using magnetically trapped Ultra-Cold Neutrons (UCNs) offer the possibility of storage without spurious losses which can provide a reliable value for the neutron lifetime. The progress towards realizing a neutron lifetime measurement using a Ioffe-type trap made with a Halbach-type permanent octupole magne...
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
Muon Knight shift measurements in possible octupole ordering system SmRu4P12
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We performed muon Knight shift measurements on randomly aligned single crystalline samples of SmRu4P12 in a magnetic field of 6 T. A marked increase in the muon spin relaxation rate was observed below a metal-insulator transition temperature, interpreted as an occurrence of finite local fields due to a dipole and/or octupole ordering. An expected magnetic anomaly at around 14 K in high fields was still obscure in a field of 6 T
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.
Zakharova, E. G.; Kireeva, I. V.; Chumlyakov, Y. I.; Shul'Mina, A. A.; Sehitoglu, H.; Karaman, I.
2004-06-01
On single crystals of Hadfield steel (Fe-13Mn-1.3C, Fe-13Mn-2.7Al-1.3C, wt.%) the systematical investigations of deformation mechanisms - slip and twinning, stages of plastic flow, strain hardening coefficient depending on orientation of tensile axis have been carried out by methods of optical and electron microscopy, x-ray analysis. Is has been shown that the combination of low stacking fault energy (?{SF}=0.03J/m^2) with high concentration of carbon atoms in aluminium-free steel results in development of the mechanical twinning at room temperature in all crystal orientations. The new type of twinning with formation of extrinsic stacking fault has been found out in [001] single crystals. Experimentally it has been established that alloying with aluminium leads to increase of stacking fault energy of Hadfield steel and suppresses twinning in all orientations of crystals at preservation of high values of strain-hardening coefficients ?.
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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.
Bulk crustal properties in NE Tibet and its implication for deformation model
Tian, Xiaobo
2014-05-01
The crust beneath the northeastern (NE) Tibetan Plateau records far field effects of collision and convergence occurring between the Indian and Eurasian plates. A better structural understanding of the crust beneath NE Tibet can improve our understanding of Cenozoic deformation resulting from the India-Eurasia collision. Taking advantage of the relatively dense coverage in most areas in NE Tibet except for the Qaidam basin by regional seismic networks of Gansu and Qinghai Provinces, we isolate receiver functions from the teleseismic P wave data recorded from 2007 to 2009 and resolve the spatial distribution of crustal thickness and Vp/Vs ratio beneath NE Tibet from H-K scanning. Our results can be summarized as: (1) NE Tibet is characterized by ~ 60-km-thick crust beneath the Nan Shan, Qilian Shan thrust belts and the Anyemaqen Shan, and 45-50 km-thick crust beneath the Tarim basin, the Alashan depression and the Ordos basin; the crust thins gradually from west to east in addition to the previously observed pronounced thinning from south to north; (2) the crust of NE Tibet exhibits a relatively lower Vp/Vs ratio of 1.72 than the north China block and a decrease in average crustal Vp/Vs ratio with increasing crustal thickness; and (3) the crustal thicknesses are less than the values predicted by the simple isostatic model of throughout Tibetan plateau in where the elevation is larger than 3.0 km. Our observations can be explained by the hypothesis that deformation occurring in NE Tibet is predominated by upper-crustal thickening or lower-crust extrusion.
Effect of the Spinning Deformation Processing on Mechanical Properties of Al-7Si-0.3Mg Alloys
Cheng, Yin-Chun; Lin, Chih-Kuang; Tan, An-Hung; Hsu, Shih-Yuan; Lee, Sheng-Long
2012-09-01
This study investigates the mechanical properties of Al-7Si-0.3Mg (A356) alloy affected by the spinning deformation processing (SDP). The cast structure of the A356 alloy becomes elongated with increasing reduction in thickness. This leads to reduction of casting defects, and refines and distributes the eutectic silicon phase throughout the Al-matrix. The hardness tends to reach a steady value due to the uniformity of the microstructure with the reduction in thickness. The SDP leads to a re-arrangement in the eutectic region, which forces the propagation of cracks through the ductile ?-Al phase. The tensile strength and elongation increases accordingly. The improvement on tensile strength and elongation produces the best quality index for A356 alloy.
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The 500 keV Xe2+ irradiation-induced anisotropic deformation of ordered colloidal silica nanoparticulate masks is followed using 2 MeV 4He+ Rutherford Backscattering Spectrometry (RBS) with different measurement geometries and the improved data analysis capabilities of the RBS-MAST spectrum simulation code. The three-dimensional (3D) geometrical transformation from spherical to oblate ellipsoidal and polygonal shape and the decrease of the mask's hole size is described. The masking properties of the silica monolayer and the depth distribution of Xe in the underlying Si substrate vs. the irradiated Xe2+ fluence are discussed. Field Emission Scanning Electron Microscopy (FESEM) is applied as complementary characterization tool. Our results give contribution to clarify the impact of ion-nanoparticle interactions on the potentials and limits of nanosphere lithography. We also show the capability of the conventional RBS technique to characterize laterally ordered submicron-sized three-dimensional structures.
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.
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Highlights: ? Mechanical properties and microstructural evolution of cryorolled + warm rolled (WR) Al 5083 alloy were investigated. ? WR samples showed a significant improvement in tensile strength and ductility (6.8%) than CR samples. ? WR sample is thermally stable up to 250 °C. ? YS and UTS of WR sample annealed at 250 °C are 270 MPa and 330 MPa, respectively, and elongation to failure is 13%. - Abstract: Aluminum–Magnesium (Al 5083) alloy was subjected to cryorolling (CR) and cryorolling followed by warm rolling (WR) in order to investigate the changes in mechanical behavior and microstructure evolution in the present work. Al alloy specimens were first cryorolled up to 50% thickness reduction followed with warm rolling at 100 °C, 145 °C, 175 °C and 200 °C till to achieve total 90% thickness reduction. The final microstructure of all conditions were analyzed and compared through transmission electron microscopy (TEM), Electron back scattered diffraction (EBSD), and X-ray diffraction (XRD) techniques to investigate the effect of WR deformation temperatures on mechanical properties. The mechanical behavior of the processed samples were evaluated through hardness and tensile tests performed at room temperature. An increase in yield strength (522 MPa), ultimate tensile strength (539 MPa) and ductility (6.8%) was observed in WR specimens at 175 °C, hardness also increases to (146 HV) as compared to CR samples. These samples were annealed in temperature range from 150 °C to 300 °C to investigate their thermal stability. The CR samples exhibited severely deformed structure with high dislocation density network while cryorolled followed by warm rolled (WR) samples has shown formation of ultrafine grains associated with dynamic recovery. At elevated temperature of 200 °C, WR samples showed decrease in strength accompanied with increase in elongation due to dominant dynamic recovery effect led to reduction in dislocation density
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Research highlights: ? New renewable and biodegradable Agave americana fibre. ? Environmentally free materials. ? Good mechanical properties of Agave fibre reinforced epoxy composite materials. ? Surface modification of the fibre (Alkali treatment) imported good mechanical properties. ? Future scope in light weight materials manufacture. -- Abstract: The mechanical properties such as tensile, compressive, flexural, impact strength and water absorption of the alkali treated continuous Agave fibre reinforced epoxy composite (TCEC) and untreated continuous Agave fibre reinforced epoxy composite (UTCEC) were analysed. A comparison of the surfaces of TCEC and UTCEC composites was carried out by dynamic mechanical analysis (DMA), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The thermomechanical properties of the composite reinforced with sodium hydroxide (NaOH) treated Agave fibres were considerably good as the shrinkage of the fibre during alkali treatment had facilitated more points of fibre resin interface. The SEM micrograph and FTIR spectra of the impact fracture surfaces of TCEC clearly demonstrate the better interfacial adhesion between fibre and the matrix. In both analyses the TCEC gave good performance than UTCEC and, thus, there is a scope for its application in light weight manufacture in future.
Annealing behaviour and mechanical properties of severely deformed interstitial free steel
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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 anical properties depend on both, grain size and area fraction of HAGBs.
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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)
Enhanced magnetic properties and bending strength of hot deformed Nd-Fe-B magnets with Cu additions
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Commercial rapidly-quenched Nd-Fe-B ribbons blended with fine Cu powders (10-30 ?m) were hot pressed to obtain fully dense magnets and then die upset into highly anisotropic, oriented magnets. The effects of Cu addition on the magnetic properties and bending strength of hot deformed Nd-Fe-B magnets were investigated. It was found that the coercivity (Hcj) and maximum energy product (BH)max as well as the bending strength were enhanced significantly by Cu addition. Detailed microstructural investigations were carried out by transmission electron microscopy/high-resolution transmission electron microscopy (TEM/HRTEM). It shows that there are two types of grain boundaries in Cu-doped magnet, one is parallel and the other is trigonal. However, energy dispersive X-rays (EDX) analyses indicate that the two type intergranular phases are NdCu2. Analyses indicate that the enhanced texture of Cu-doped magnet is due to the lower melting point of the intergranular phase, leading to the enhancement in magnetic properties. Improvement of bending stress in Cu-doped magnet is related to the trigonal grain boundaries and the rheology of the intergranular phase.
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V. I. Semenov
2011-06-01
Full Text Available This paper presents the results of tribological investigations conducted on steel 20 with the carbon content of up to 0.2%. The steel was studied in the three conditions: initial (hot-rolled, after heat-treatment (quenching+tempering and after heat treatment with subsequent severe plastic deformation (SPD performed by equal channel angular pressing technique (ECAP. It was stated that after various treatments the material acquires various structural conditions and possesses various strength properties and has a considerable difference in oxygen content in the surface layer. This influences the tribological properties during the contact with tool steel. The lowest values of adhesive bond shear strength, friction coefficient and wear rate are demonstrated in the material after martempering with subsequent SPD by ECAP technique. The surface of the investigated material after SPD treatment by the ECAP technique possesses a highest bearing capacity and requires more time for wearing-in in friction assemblies. Oxygen content increase in the form of metal oxides on the surface of low-carbon steels is accompanied by a decrease of the adhesive component of friction coefficien.
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.
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Knee meniscus is a hydrated tissue; it is a fibrocartilage of the knee joint composed primarily of water. We present results of interferometric surface monitoring by which we measure physical properties of human knee meniscal cartilage. The physical response of biological tissue to a short laser pulse is primarily thermomechanical. When the pulse is shorter than characteristic times (thermal diffusion time and acoustic relaxation time) stresses build and propagate as acoustic waves in the tissue. The tissue responds to the laser-induced stress by thermoelastic expansion. Solving the thermoelastic wave equation numerically predicts the correct laser-induced expansion. By comparing theory with experimental data, we can obtain the longitudinal speed of sound, the effective optical penetration depth and the Grueneisen coefficient. This study yields information about the laser-tissue interaction and determines properties of the meniscus samples that could be used as diagnostic parameters. (author)
Corneal Viscoelastic Properties from Finite-Element Analysis of In Vivo Air-Puff Deformation
Sabine Kling; Nandor Bekesi; Carlos Dorronsoro; Daniel Pascual; Susana Marcos.
2014-01-01
Biomechanical properties are an excellent health marker of biological tissues, however they are challenging to be measured in-vivo. Non-invasive approaches to assess tissue biomechanics have been suggested, but there is a clear need for more accurate techniques for diagnosis, surgical guidance and treatment evaluation. Recently air-puff systems have been developed to study the dynamic tissue response, nevertheless the experimental geometrical observations lack from an analysis that addresses ...
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...
Mobility of vacancies under deformation and their effect on the elastic properties of graphene
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The effect of isolated vacancies on the elastic properties of a graphene sheet has been investigated by the ab initio density functional method. An almost inverse linear dependence of the Young’s modulus on the concentration of vacancies has been revealed. The height of potential barriers for the motion of vacancies in various directions has been calculated as a function of various independent applied strains. The velocity of vacancies at various temperatures has been calculated as a function of applied strains using the transition state theory.
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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.)
Magnetic Field Induced 4f Octupole in CeB6 Probed by Resonant X-Ray Diffraction
Matsumura, Takeshi; Yonemura, Takumi; Kunimori, Keisuke; Sera, Masafumi; Iga, Fumitoshi
2009-07-01
A mysterious antiferroquadrupolar ordered phase of CeB6 is considered as originating from the Txyz-type magnetic octupole moment in magnetic fields. By resonant x-ray diffraction, we have verified that the Txyz-type octupole is indeed induced in the 4f orbital of Ce with a propagation vector ((1)/(2),(1)/(2),(1)/(2)), thereby supporting the theory. We observed an asymmetric field dependence of the intensity for an electric quadrupole (E2) resonance when the field was reversed and extracted a field dependence of the octupole by utilizing the interference with an electric dipole (E1) resonance. The result is in good agreement with that of the NMR-line splitting, which reflects the transferred hyperfine field at the boron nucleus from the anisotropic spin distribution of Ce with an Oxy-type quadrupole.
Mechanical and service properties of low carbon steels processed by severe plastic deformation
Directory of Open Access Journals (Sweden)
J. Zrnik
2009-07-01
Full Text Available The structure and properties of the 0,09% C-Mn-Si-Nb-V-Ti, 0,1% C-Mn-V-Ti and 0,09% C-Mo-V-Nb low-carbon steels were studied after cold equal-channel angular pressing (ECAP. ECAP leads to the formation of partially submicrocrystalline structure with a grain size of 150 – 300 nm. The submicrocrystalline 0,09% C-Mn-Si-Nb-V-Ti steel compared with the normalized steel is characterized by Re higher more than by a factor of 2 and by the impact toughness higher by a factor of 3,5 at a test temperature of -40°C. The plasticity in this case is somewhat lower. The high-strength state of the submicrocrystalline 0,1% C-Mn-V-Ti and 0,09% C-Mo-V-Nb steels after ECAP is retained up to a test temperature of 500°C. The strength properties at 600°C (i.e. the fire resistance of these steels are higher by 20-25% as compared to those of the undeformed steels. The strength of the 0,09% C-Mo-V-Nb steel at 600°C is substantially higher than that of the 0,1% C-Mn-V-Ti steel.
Thermomechanical properties and deformation of coarse-grained models of hard-soft block copolymers.
Cui, Zhiwei; Brinson, L Catherine
2013-08-01
In this paper, we investigate the enhancement mechanism of the mechanical properties for hard-soft block copolymers by using molecular dynamics simulations at various temperatures. A coarse-grained approach is adopted to study sufficiently generic models. Our numerical experiments demonstrate that the nonbond potential plays a more significant role in mechanical properties compared to the bond potential. This finding serves as a cornerstone to understand the hard-soft materials. To explore the effect of hard segments, four copolymers with different concentrations and energy factors that describe the interaction between hard beads are conducted. Simulation results show that the mechanical performances of the system with large attractive force and small concentration of hard segments could be improved dramatically in conjunction with a moderate increment of the glass transition temperature. In particular, the energy factor shows a substantial influence in determining the microphase separation as well as the morphology of hard domains. These observations are believed to provide design guidelines for polymeric materials in engineering practice. PMID:24032857
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)
The generalized oscillator strengths (GOS's) of discrete excitations np?nd and np?(n+1)s,d, both dipole (L=1) and octupole (L=3), are studied. We demonstrate that although the relevant transitions in the same atom are closely located in energy, the dependence of their GOS's on the momentum transfer squared q2 is remarkably different; viz., the GOS's corresponding to L=3 have at least one extra maximum as a function of q2 and dominate over those of the L=1, starting from about q2=1.5 a.u. Peculiarities are noted in the GOS of only the Ne dipole 2p?3s transition in contrast to the rest of the atoms; viz., the characteristic minimum and the maximum are not obliterated by the dominance of 2p?3d GOS dipole and octupole sum as in the other atoms. The depth of the minimum of the GOS for the dipole 2p?3s transition is reduced considerably by the 2p?3d dipole and octupole GOS sums, while the corresponding maximum is enhanced. In the GOS sum both the minimum and maximum are still identifiable, permitting experimental observation. The calculations were performed in the one particle Hartree-Fock (HF) approximation and with account of many-electron correlations via the random phase approximation with exchange (RPAE). The GOS's are studied for values of q2 up to 50 a.u. Our calculated RPAE GOS's for the Ar 3p?4s dipole transition compare very well with the recently measured data of Zhu et al. [Phys. Rev. A 73, 042703 (2006)]s. Rev. A 73, 042703 (2006)
International Nuclear Information System (INIS)
From experiments, see e.g. [W. Wiese, D. Kelleher, and D. Paquette, Phys. Rev. A 6, 1132 (1972); V. Helbig and K. Nich, J. Phys. B 14, 3573 (1981).; J. Halenka, Z. Phys. D 16, 1 (1990); . Djurovic, D. Nikolic, I. Savic, S. Sorge, and A.V. Demura, Phys. Rev. E 71, 036407 (2005)], results that the hydrogen lines formed in plasma with Ne ? 1016 cm-3 are asymmetrical. The inhomogeneity of ionic micro field and the higher order corrections (quadratic and next ones) in perturbation theory are the reason for such asymmetry. So far, the ion-emitter quadrupole interaction and the quadratic Stark effect have been included in calculations. The recent work shows that a significant discrepancy between calculations and measurements occurs in the wings of H-beta line in plasmas with cm-3. It should be stressed here that e.g. for the energy operator the correction raised by the quadratic Stark effect is proportional to (where is the emitter-perturber distance) similarly as the correction caused by the emitter-perturber octupole interaction and the quadratic correction from emitter-perturber quadrupole interaction. Thus, it is obvious that a model of the profile calculation is consistent one if all the aforementioned corrections are simultaneously included. Such calculations are planned in the future paper. A statistics of the octupole inhomogeneity tensor in a plasma is necessarily needed in the first step of such calculations. For the first time the distribution functions of the octupole inhomogeneity have been calculated in this paper using the Mayer-Mayer cluster expansion method similarly as for the quadrupole function in the paper [J. Halenka, Z. Phys. D 16, 1 (1990)]. The quantity is the reduced scale of the micro field strength, where is the Holtsmark normal field and is the mean distance defined by the relationship, that is approximately equal to the mean ion-ion distance; whereas is the screening parameter, where is the electronic Debye radius. (author)
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.
Amusia, M. Ya; Chernysheva, L. V.; Felfli, Z.; Msezane, A. Z.
2007-01-01
The generalized oscillator strengths (GOS) of discrete excitations np-nd, both dipole (L=1) and octupole (L=3) are studied, the latter for the first time. We demonstrate that although the relevant transitions in the same atom are closely located in energy, the dependence of their GOS on the momentum transfer q squared, is remarkably different, so that the GOS corresponding to L=3 have at least one extra maximum as a function of q squared and dominate over those of the L=1, s...
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)
Location of the missing octupole state in magic nucleus 134Te
International Nuclear Information System (INIS)
The lowest negative parity state in all spherical even-even nuclei is found to have spin-parity 1? = 3- ; its decay transition to the 0+ ground state has the E3 (octupole) character. The global survey, and the more recent systematics of the N = 82 isotonic sequence, revealed that in this sequence the 31- remains as yet unidentified only in one case, namely the two-proton neutron-rich nucleus 134Te. It is estimated that the excitation energy of this missing state in 134Te using four different approaches and also suggest specific examination of the experimental data to identify it
Lifetimes of excited states in octupole-collective 142,144Ba nuclei
International Nuclear Information System (INIS)
Lifetimes of excited states have been measured for the positive-parity rotational bands in neutron-rich 142,144Ba as well as the 7- and 9- states of the negative-parity band in 144Ba using the differential Doppler shift method. The deduced quadrupole moment, Qt, of the positive-parity band decreases with angular momentum and overall shows good agreement with earlier measurements. The measured lifetimes of 7- and 9- states are used to determine the electric dipole moment, D0=0.17(3) and 0.09(1) e fm, respectively, in the negative-parity octupole band of 144Ba
Anisotropic Form Factors of Neutron Scattering by Magnetic Octupole in CeB6
Shiina, Ryousuke
2012-12-01
The form factor of elastic neutron scattering is calculated for the quadrupole order phase of CeB6 in magnetic fields. It is shown that the dependence of the form factor on the direction of neutron momentum transfer is very small for the Bragg reflections, whereas the scattering due to field-induced octupoles gives rise to a significant anisotropy of the form factor for the super-lattice reflections. These results are discussed in quantitative comparison with recent exprimental results. The similarity and dissimilarity with the results for phase IV in Ce1-xLaxB6 is also discussed.
Electrical and optical properties of stacking faults introduced by plastic deformation in 4H-SiC
International Nuclear Information System (INIS)
The electrical and optical properties of stacking faults (SFs) introduced by plastic deformation in 4H-SiC were studied by Electron Beam Induced Current (EBIC) and cathodoluminescence (CL) methods. Partial dislocations and stacking faults in the (0001) glide planes perpendicular to the surface were introduced in n-type 4H-SiC under a well-controlled state of stress by cantilever bending at 550°C. CL measurements allow determining the multiplicity of the SFs (single or double). It is observed that the overwhelming majority of stacking faults are double Shockley type SFs (CL emission at 504 nm) that correlates well with previously published high resolution transmission electron microscopy (HRTEM) investigations. However, single Shockley type SFs (CL emission at 422 nm) of much smaller lengths are also observed in some areas near the scratched region from where the defects are nucleated. This suggests that the velocity of partial dislocation pairs under a given applied stress could be higher than that of single partial dislocations. It is also shown that in the EBIC mode, SFs produce a strong bright contrast, which can be explained by considering the SFs in 4H-SiC to be quantum wells of II type
Wang, Haopeng
With the recent advances in processing and catalyst technology, novel morphologies have been created in crystalline polymers and they are expected to substantially impact the properties. To reveal the structure-property relationships of some of these novel polymeric systems becomes the primary focus of this work. In the first part, using an innovative layer-multiplying coextrusion process to obtain assemblies with thousands of polymer nanolayers, dominating "in-plane" lamellar crystals were created when the confined poly(ethylene oxide) (PEO) layers were made progressively thinner. When the thickness was confined to 25 nanometers, the PEO crystallized as single, high-aspect-ratio lamellae that resembled single crystals. This crystallization habit imparted more than two orders of magnitude reduction in the gas permeability. The dramatic decrease in gas permeability was attributed to the reduced diffusion coefficient, because of the increase in gas diffusion path length through the in-plane lamellae. The temperature dependence of lamellar orientation and the crystallization kinetics in the confined nanolayers were also investigated. The novel olefinic block copolymer (OBC) studied in the second part consisted of long crystallizable sequences with low comonomer content alternating with rubbery amorphous blocks with high comonomer content. The crystallizable blocks formed lamellae that organized into space-filling spherulites even when the fraction of crystallizable block was so low that the crystallinity was only 7%. These unusual spherulites were highly elastic and recovered from strains as high as 300%. These "elastic spherulites" imparted higher strain recovery and temperature resistance than the conventional random copolymers that depend on isolated, fringed micellar-like crystals to provide the junctions for the elastomeric network. In the third part, positron annihilation lifetime spectroscopy (PALS) was used to obtain the temperature dependence of the free volume hole size in propylene/ethylene copolymers over a range in comonomer content. Above the glass transition temperature (Tg), the reduced free volume hole size and the densification of the amorphous phase were attributed to constraint imposed on rubbery amorphous chain segments by attached chain segments in crystals. However constant free volume fraction was found at Tg, across the crystallinity range of the copolymers, in agreement with the iso-free volume concept of glass transition.
Hamiel, Y.; Fialko, Y.
2007-12-01
We study the structure and mechanical properties of faults in the North Anatolian Fault system by observing near- fault deformation induced by the 1999 Mw7.4 Izmit earthquake (Turkey). We use interferometeric Synthetic Aperture Radar (InSAR) and Global Positioning System (GPS) observations to analyze the coseismic surface deformation in the near field of the Izmit rupture. The overall observed coseismic deformation is consistent with deformation predicted by a dislocation model assuming a uniform elastic crust. Previous InSAR studies revealed small-scale changes in the radar range across the nearby faults of the North Anatolian fault system. We demonstrate that these anomalous range changes are consistent with an elastic response of compliant fault zones to the stress perturbation induced by the Izmit earthquake. We examine the spatial variations and mechanical properties of fault zones around the Mudurnu Valley and Iznik faults using three-dimensional finite element models. In these models, we include compliant fault zones having various geometries and elastic properties, and apply stress changes deduced from a kinematic slip model of the Izmit earthquake. The best- fitting models suggest that the inferred fault zones have a characteristic width of a few kilometers, depth in excess of 10 km, and reductions in the effective shear modulus of about a factor of 3 compared to the surrounding rocks. The characteristic width of the best-fitting fault zone models is consistent with field observations along the North Anatolian Fault system [Ambraseys, 1970]. Our results are also in agreement with InSAR observations of small- scale deformation on faults in the Eastern California Shear Zone in response to the 1992 Landers and 1999 Hector Mine earthquakes [Fialko et al., 2002; Fialko, 2004]. The inferred compliant fault zones likely represent intense damage and may be quite commonly associated with large crustal faults.
Hamiel, Yariv; Fialko, Yuri
2007-07-01
We study the structure and mechanical properties of faults in the North Anatolian Fault system by observing near-fault deformation induced by the 1999 Mw 7.4 Izmit earthquake (Turkey). We use interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System observations to analyze the coseismic surface deformation in the near field of the Izmit rupture. The overall observed coseismic deformation is consistent with deformation predicted by a dislocation model assuming a uniform elastic crust. Previous InSAR studies revealed small-scale changes in the radar range across the nearby faults of the North Anatolian fault system (in particular, the Mudurnu Valley and Iznik faults) (e.g., Wright et al., 2001). We demonstrate that these anomalous range changes are consistent with an elastic response of compliant fault zones to the stress perturbation induced by the Izmit earthquake. We examine the spatial variations and mechanical properties of fault zones around the Mudurnu Valley and Iznik faults using three-dimensional finite element models. In these models, we include compliant fault zones having various geometries and elastic properties and apply stress changes deduced from a kinematic slip model of the Izmit earthquake. The best fitting models suggest that the inferred fault zones have a characteristic width of a few kilometers, depth in excess of 10 km, and reductions in the effective shear modulus of about a factor of 3 compared to the surrounding rocks. The characteristic width of the best fitting fault zone models is consistent with field observations along the North Anatolian Fault system (Ambraseys, 1970). Our results are also in agreement with InSAR observations of small-scale deformation on faults in the Eastern California Shear Zone in response to the 1992 Landers and 1999 Hector Mine earthquakes (Fialko et al., 2002; Fialko, 2004). The inferred compliant fault zones likely represent intense damage and may be quite commonly associated with large crustal faults.
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.)
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
Tetrahedral and Triangular Deformations of $Z=N$ Nuclei in Mass Region $A \\sim 60-80$
Takami, S; Matsuo, M
1998-01-01
We study static non-axial octupole deformations in proton-rich $Z=N$ nuclei, $^{64}$Ge, $^{68}$Se, $^{72}$Kr, $^{76}$Sr, $^{80}$Zr and $^{84}$Mo, by using the Skyrme Hartree-Fock plus BCS calculation with no restrictions on the nuclear shape. The calculation predicts that the oblate ground state in $^{68}$Se is extremely soft for the $Y_{33}$ triangular deformation, and that in $^{80}$Zr the low-lying local minimum state coexisting with the prolate ground state has the $Y_{32}$ tetrahedral deformation.
Construction and Operational Experience with a Superconducting Octupole Used to Trap Antihydrogen
Energy Technology Data Exchange (ETDEWEB)
Wanderer P.; Escallier, J.; Marone, A.; Parker, B.
2011-09-06
A superconducting octupole magnet has seen extensive service as part of the ALPHA experiment at CERN. ALPHA has trapped antihydrogen, a crucial step towards performing precision measurements of anti-atoms. The octupole was made at the Direct Wind facility by the Superconducting Magnet Division at Brookhaven National Laboratory. The magnet was wound with a six-around-one NbTi cable about 1 mm in diameter. It is about 300 mm long, with a radius of 25 mm and a peak field at the conductor of 4.04 T. Specific features of the magnet, including a minimal amount of material in the coil and coil ends with low multipole content, were advantageous to its use in ALPHA. The magnet was operated for six months a year for five years. During this time it underwent about 900 thermal cycles (between 4K and 100K). A novel operational feature is that during the course of data-taking the magnet was repeatedly shut off from its 950 A operating current. The magnet quenches during the shutoff, with a decay constant of 9 ms. Over the course of the five years, the magnet was deliberately quenched many thousands of times. It still performs well.
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.
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)
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...
Sarriguren, P
2015-01-01
Beta-decay properties of even and odd-A neutron-rich Ge, Se, Kr, Sr, Ru, and Pd isotopes involved in the astrophysical rapid neutron capture process are studied within a deformed proton-neutron quasiparticle random-phase approximation. The underlying mean field is described self-consistently from deformed Skyrme Hartree-Fock calculations with pairing correlations. Residual interactions in the particle-hole and particle-particle channels are also included in the formalism. The isotopic evolution of the various nuclear equilibrium shapes and the corresponding charge radii are investigated in all the isotopic chains. The energy distributions of the Gamow-Teller strength as well as the beta-decay half-lives are discussed and compared with the available experimental information. It is shown that nuclear deformation plays a significant role in the description of the decay properties in this mass region. Reliable predictions of the strength distributions are essential to evaluate decay rates in astrophysical scenari...
Amusia, M Ya; Felfli, Z; Msezane, A Z
2007-01-01
The generalized oscillator strengths (GOS) of discrete excitations np-nd, both dipole (L=1) and octupole (L=3) are studied, the latter for the first time. We demonstrate that although the relevant transitions in the same atom are closely located in energy, the dependence of their GOS on the momentum transfer q squared, is remarkably different, so that the GOS corresponding to L=3 have at least one extra maximum as a function of q squared and dominate over those of the L=1, starting from about q=1.25$ atomic unit (a.u.). The calculations were performed in the one particle Hartree-Fock approximation and with account of many-electron correlations via the Random Phase Approximation with Exchange. The GOS are studied for values of q squared up to 30 a.u.
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
Octupole magnet for soft X ray magnetic dichroism experiments: Design and performance
International Nuclear Information System (INIS)
An octupole magnet endstation for soft x-ray magnetic dichroism measurements has been developed at the Advanced Light Source. The system consists of an eight pole electromagnet that surrounds a small vacuum chamber. The magnet provides fields up to 0.9 T that can be applied in any direction relative to the incoming x-ray beam. High precision magnetic circular and linear dichroism spectra can be obtained reversing the magnetic field for each photon energy in an energy scan. Moreover, the field dependence of all components of the magnetization vector can be studied in detail by choosing various angles of x-ray incidence while keeping the relative orientation of magnetic field and sample fixed
International Nuclear Information System (INIS)
Boron nitride nanotubes (BNNT) reinforced aluminum based composites are synthesized by spark plasma sintering (SPS). The concentration of BNNT is varied as 0, 2 and 5 vol% in the aluminum matrix. Micro-pillar compression testing revealed that Al–5 vol% BNNT has yield strength and compressive strength as 88 MPa and 216 MPa respectively, which is more than 50% improvement over unreinforced Al. BNNT play an active role in strengthening Al matrix through effective load bearing and transfer by crack bridging and sword in sheath mechanisms. Cold rolling of Al–5 vol% BNNT with 75% thickness reduction in a single pass exhibited high deformability without cracking or disintegration. The deformation is dominated by slip signifying ductile behavior in sintered Al with and without BNNT. BNNT survives the extreme temperature and pressure conditions during SPS processing and heavy deformation during cold rolling
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)
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.
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.
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.
International Nuclear Information System (INIS)
For a conformal theory it is natural to seek the conformal moduli space, Mc to which it belongs, generated by the exactly marginal deformations. By now we should have the tools to determine Mc in the presence of enough supersymmetry. Here it is shown that its dimension is determined in terms of a certain index. Moreover, the D-term of the global group is an obstruction for deformation, in presence of a certain amount of preserved supersymmetry. As an example we find that the deformations of the membrane (3d) field theory, under certain conditions, are in 35/SL(4,C). Other properties including the local geometry of Mc are discussed. (author)
International Nuclear Information System (INIS)
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.
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.
Directory of Open Access Journals (Sweden)
Shao-Yi Lin
2013-12-01
Full Text Available In this study multi-component (AlCrTaTiZrNxSiy high-entropy coatings were developed by co-sputtering of AlCrTaTiZr alloy and Si in an Ar/N2 mixed atmosphere with the application of different substrate biases and Si-target powers. Their nanomechanical properties and deformation behaviors were characterized by nanoindentation tests. Because of the effect of high mixing entropies, all the deposited multi-component (AlCrTaTiZrNxSiy high-entropy coatings exhibited a simple face-centered cubic solid-solution structure. With an increased substrate bias and Si-target power, their microstructures changed from large columns with a [111] preferred orientation to a nanocomposite form with ultrafine grains. The hardness, H/E ratio and H3/E2 ratio of (AlCrTaTiZrN1.07Si0.15 coating reached 30.2 GPa, 0.12 and 0.41 GPa, respectively, suggesting markedly suppressed dislocation activities and a very high resistance to wear and plastic deformation, attributable to grain refinements and film densification by the application of substrate bias, a nanocomposite structure by the introduction of silicon nitrides, and a strengthening effect induced by severe lattice distortions. In the deformed regions under indents, stacking faults or partial dislocations were formed, while in the stress-released regions, near-perfect lattices recovered.
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.
International Nuclear Information System (INIS)
Program package and numerical solution of the problem for a system of coupled equations used in optical model to solve a problem on low and mean energy neutron scattering on deformed nuclei, is considered. With these programs differnet scattering cross sections depending on the incident neutron energy on even-even and even-odd nuclei were obtained. The programm permits to obtain different scattering cross sections (elastic, inelastic), excitation cross sections of the first three energy levels of rotational band depending on the energy, angular distributions and neutron polarizations including excited channels. In the program there is possibility for accounting even-even nuclei octupole deformation
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.
International Nuclear Information System (INIS)
The octupole degree of freedom of the nuclei 218-230Ra and 222-230Th is investigated in a microscopic way. Our analysis is based on the constrained Hartree-Fock plus BCS theory as well as on the adiabatic time-dependent Hartree-Fock in the cranking approximation (and generator coordinate method plus mean field). In the numerical applications we use the Gogny forces. From the mean field calculations we show octupole barrier heights, dipole moments as well as the values of ?2, ?4, ?5, ?6 and ?7 along the constrained path. From the symmetry conserving calculations we display the 0+-1- splitting, wave functions as well as the E1 and E3 transition probabilities. The overall agreement with the available experimental data is very good. (orig.)
International Nuclear Information System (INIS)
An evaluation of data obtained in (n,n'?) experiments reveals strong M1 3-i ? 3-1 transitions in nuclei near the N=50 (92Zr, 94Mo and 96Mo), Z=50 (112Cd and 114Cd) and N=82 (144Nd) shell closures. The observed left angle 31- M1 3i- right angle matrix elements scale with the left angle 21+ parallel M1 parallel 2+ms right angle matrix elements, and the energy difference between the initial 3-i state and the 3-1 octupole phonon is proportional to the left angle 3-1 parallel E3 parallel 0+gs right angle matrix element. The possibility of assigning the states of interest as octupole mixed-symmetry states is discussed.
International Nuclear Information System (INIS)
An evaluation of data obtained in (n,n'?) experiments reveals strong M1 3i-?31- transitions in nuclei near the N=50 (92Zr, 94Mo, and 96Mo), Z=50 (112Cd and 114Cd), and N=82 (144Nd) shell closures. The observed 1-||M1||3i-> matrix elements scale with the 1+||M1||2ms+> matrix elements connecting the mixed-symmetric and symmetric quadrupole excitations. In accordance with a picture of a mixed two-component quantum system, the energy difference between the initial 3i- state and the 31- octupole phonon is proportional to the |1-||E3||0gs+>| matrix element. The possibility of assigning the 3- states of interest as octupole isovector states is discussed.
Smirnova, N A; Mizusaki, T; Van Isacker, P; Smirnova, Nadya A.; Pietralla, Norbert; Mizusaki, Takahiro; Isacker, Piet Van
2000-01-01
The interrelation between the octupole phonon and the low-lyingproton-neutron mixed-symmetry quadrupole phonon in near-spherical nuclei isinvestigated. The one-phonon states decay by collective E3 and E2 transitionsto the ground state and by relatively strong E1 and M1 transitions to theisoscalar 2^+ state. We apply the proton-neutron version of the InteractingBoson Model including quadrupole and octupole bosons (sdf-IBM-2). Two F-spinsymmetric dynamical symmetry limits of the model, namely the vibrational andthe $\\gamma$-unstable ones, are considered. We derive analytical formulae forexcitation energies as well as B(E1), B(M1), B(E2) and B(E3) values for anumber of transitions between low-lying states. The model well reproduces manyknown transition strengths in the near spherical nuclei ^{142}Ce and ^{94}Mo.
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
International Nuclear Information System (INIS)
We study null 1/4 BPS deformations of flat domain wall solutions (NDDW) in N = 2, d = 5 gauged supergravity with hypermultiplets and vector multiplets coupled. These are uncharged time-dependent configurations and contain as special case, 1/2 supersymmetric flat domain walls (DW), as well as 1/2 BPS null solutions of the ungauged supergravity. Combining our analysis with the classification method initiated by Gauntlett et al., we prove that all the possible deformations of the DW have origin in the hypermultiplet sector or/and are null. Here, we classify all the null deformations: we show that they naturally organize themselves into 'gauging' (v-deformation) and 'non gauging' (u-deformation). They have different properties: only in presence of v-deformation is the solution supported by a time-dependent scalar potential. Furthermore we show that the number of possible deformations equals the number of matter multiplets coupled. We discuss the general procedure for constructing explicit solutions, stressing the crucial role taken by the integrability conditions of the scalars as spacetime functions. Two analytical solutions are presented. Finally, we comment on the holographic applications of the NDDW, in relation to the recently proposed time-dependent AdS/CFT
Celi, A
2007-01-01
We study null 1/4 BPS deformations of flat Domain Wall solutions (NDDW) in N=2, d=5 gauged supergravity with hypermultiplets and vector multiplets coupled. These are uncharged timedependent configurations and contain as special case, 1/2 supersymmetric flat domain walls (DW) and, as well, 1/2 BPS null solutions of the ungauged supergravity. Combining our analysis with the classification method initiated by Gauntlett et al., we prove that all the possible deformations of the DW have origin in the hypermultiplet sector or/and are null. Here, we classify all the null deformations: we show that they naturally organize in "gauging" (v-deformation) and "non gauging" (u-deformation). They have different properties: only in presence of v-deformation the solution is supported by a timedependent scalar potential. Furthermore we show that u-deformation forces the number of multiplets coupled to be different by one. We discuss the general procedure for constructing explicit solutions, stressing the crucial role taken by ...
Guo, Xiaodong; Helseth, Lars Egil
2015-01-01
We demonstrate that nanostructured fluorinated ethylene propylene (FEP) polymer films undergo a non-reversible structural transition when exposed to an applied force. While reactive ion etching (RIE) treatment creates FEP films with well-defined nanostructures, applied stress causes a permanent deformation which alters the optical reflectance spectrum. The structural changes of the FEP films also altered the contact angles of water droplets. It was found that the contact angles changed from 109° before to 139° after RIE treatment, and plastic deformation reduced the contact angles to 111°. Scanning electron microscopy images revealed freshly formed homogeneous surfaces, with nanostructures hidden below, which correlated with the macroscopic changes in optical reflectance. Interestingly, the contact electrification between FEP and aluminum did not change when the nanostructures were deformed, and we propose that the nanostructured FEP surface can be used to both optically monitor the state of the nanostructure as well as functioning as a part of an energy harvesting system. At an average power of about 22 ?W with an area of 4 cm2, the energy harvester is able to light up a large number of light emitting diodes.
Search for two-phonon octupole vibrational bands in 88,89,92,93,94,96Sr and 95,96,97,98Zr
International Nuclear Information System (INIS)
Several new gamma transitions were identified in 94Sr, 93Sr, 92Sr, 96Zr and 97Zr from the spontaneous fission of 252Cf. Excited states in 88,89,92,94,96Sr and 95,96,97,98Zr were reanalyzed and reorganized to propose the new two-phonon octupole vibrational states and bands. The spin and parity of 6+ are assigned to a 4034.5 keV state in 94Sr and 3576.4 keV state in 98Zr. These states are proposed as the two-phonon octupole vibrational states along with the 6+ states at 3483.4 keV in 96Zr, at 3786.0 keV in 92Sr and 3604.2 keV in 96Sr. The positive parity bands in 88,94,96Sr and 96,98Zr are the first two-phonon octupole vibrational bands based on a 6+ state assigned in spherical nuclei. It is thought that in 94,96Sr and 96,98Zr a 3- octupole vibrational phonon is weakly coupled to an one-phonon octupole vibrational band to make the two-phonon octupole vibrational band. Also, the high spin states of odd-A95Zr and 97Zr are interpreted to be generated by the neutron 2d5/2 hole and neutron 1g7/2 particle, respectively, weakly coupled to one- and two-phonon octupole vibrational bands of 96Zr. The high spin states of odd-A87Sr are interpreted to be caused by the neutron 1g9/2 hole weakly coupled to 3- and 5- states of 88Sr. New one- and two-POV bands in 95,97Zr and 87,89Sr are proposed, for the first time, in the present work. (author)
Petrova, A.; Brodova, I.; Shorokhov, E.; Plekhov, O.; Naimark, O.
2014-08-01
This paper presents experimental results on the thermodynamics of deformation process and mechanical behavior of the ultrafine grained aluminum alloys under dynamic compression. Dynamic compression tests were performed on a Hopkinson-Kolsky split bar at the strain rate of 103 s'1 with simultaneously recording the surface temperature of samples by an infrared camera. Energy dissipation ability was determined for ultrafine-grained alloys. An inverse strain rate dependency of dynamic yield strength was observed in the ultrafine-grained Al-Zn-Mg-Cu alloy (A7075).
Timescales of Kozai-Lidov oscillations at quadrupole and octupole order in the test particle limit
Antognini, Joseph M O
2015-01-01
Kozai-Lidov (KL) oscillations in hierarchical triple systems have found application to many astrophysical contexts, including planet formation, type Ia supernovae, and supermassive black hole dynamics. The period of these oscillations is known at the order-of-magnitude level, but dependences on the initial mutual inclination or inner eccentricity are not typically included. In this work I calculate the period of KL oscillations ($t_{\\textrm{KL}}$) exactly in the test particle limit at quadrupole order (TPQ). I explore the parameter space of all hierarchical triples at TPQ and show that except for triples on the boundary between libration and rotation, the period of KL oscillations does not vary by more than a factor of a few. The exact period may be approximated to better than 2 per cent for triples with mutual inclinations between 60$^{\\circ}$ and 120$^{\\circ}$ and initial eccentricities less than $\\sim$0.3. In addition, I derive an analytic expression for the period of octupole-order oscillations due to the...
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.
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.
Delta I = 1 staggering in octupole bands of light actinides "Beat" patterns
Bonatsos, Dennis; Drenska, S B; Karoussos, N; Minkov, N; Raychev, P P; Roussev, R P
2001-01-01
The Delta I = 1 staggering (odd--even staggering) in octupole bands of light actinides is found to exhibit a ``beat'' behaviour as a function of the angular momentum I, forcing us to revise the traditional belief that this staggering decreases gradually to zero and then remains at this zero value. Various algebraic models (spf-Interacting Boson Model, spdf-IBM, Vector Boson Model, Nuclear Vibron Model) are shown to predict in their su(3) limits constant staggering for this case, being thus unable to describe the ``beat'' behaviour. An explanation of the ``beat'' behaviour is given in terms of two Dunham expansions (expansions in terms of powers of I(I+1)) with slightly different sets of coefficients for the ground state band and the negative parity band, the difference in the values of the coefficients being attributed to Coriolis couplings to other negative parity bands. Similar ``beat'' patterns have already been seen in rotational bands of some diatomic molecules, like AgH.
International Nuclear Information System (INIS)
The aims of the paper are: 1) an investigation of the influence of the parameters k, ? of the modified oscillator potential on the calculation of the surface of the total potential energy (PE) of the nuclei Tl, Au, Ir, Re, and on the energy of the lowest level 9/2- of these nuclei; 2) a comparison of the experimental and calculated parameters of the quadrupole deformation of such nuclides in the ground and single-particle states with negative parity. A comparison of the experimental excitation energies of the levels 9/2- in odd isotopes of Tl, Au, Ir and Re, taking into account data on the PE, calculated from the Nilsson microscopic model for different sets of the parameters ksub(p), ?sub(p), tells in favour of the ''standard'' set (ksub(p)(N)=0.0618 and ?sub(p)(N)=0.616. Agreement is established between the calculated values of the parameters of quadrupole deformation, based on an analysis of the surface of the PE and the corresponding semi-empirical values obtained from the reduced transition probabilities. Noticeable divergence is found for light isotopes of iridium and heavy isotopes of thallium
Choi, Chulmin; Hong, Soonkook; Chen, Li-Han; Liu, Chin-Hung; Choi, Duyoung; Kuru, Cihan; Jin, Sungho
2014-05-01
Vertically anisotropically conductive composites with aligned chain-of-spheres of 20-75 mm Ni particles in an elastomer matrix have been prepared by curing the mixture at 100°C-150°C under an applied magnetic field of ˜300-1000 Oe. The particles are coated with a ˜120 nm thick Au layer for enhanced electrical conductivity. The resultant vertically aligned but laterally isolated columns of conductive particles extend through the whole composite thickness and the end of the Ni columns protrude from the surface, contributing to enhanced electrical contact on the composite surface. The stress-strain curve on compressive deformation exhibits a nonlinear behavior with a rapidly increasing Young's modulus with stress (or pressure). The electrical contact resistance Rc decreases rapidly when the applied pressure is small and then more gradually after the applied pressure reaches 500 psi (˜3.4 MPa), corresponding to a 30% deformation. The directionally conductive elastomer composite material with metal pads and conductive electrodes on the substrate surface can be used as a convenient tactile shear sensor for applications involving artificial limbs, robotic devices, and other visual communication devices such as touch sensitive screens.
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 (Russian Foundation for Basic Research.
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.)
International Nuclear Information System (INIS)
The influences of deformation, heat treatment temperature and holding time on morphology and size distribution of Si containing eutectic phases of Thixocast Al-7Si-0.4 Mg alloy were investigated. The novel thermo-mechanical treatment consisted of initial cold working practice followed by a solution heat treatment at 540 deg. C for durations ranging from 2 min to 120 min followed by water quenching. Optical and scanning electron microscopes were used to study the influence of process parameters on microstructure evolution. Also, final mechanical properties were investigated using hardness test. The results indicate that, under appropriate conditions it is possible to achieve an ultrafine grain microstructure with the eutectic Si fibers fragmented and spheroidized in the entire microstructure. It was also found that, an agglomeration of sphrodized particles occurs and is governed by Ostwald ripening mechanism.
Deformed logarithms and entropies
Kaniadakis, G; Scarfone, A M
2004-01-01
By solving a differential-functional equation inposed by the MaxEnt principle we obtain a class of two-parameter deformed logarithms and construct the corresponding two-parameter generalized trace-form entropies. Generalized distributions follow from these generalized entropies in the same fashion as the Gaussian distribution follows from the Shannon entropy, which is a special limiting case of the family. We determine the region of parameters where the deformed logarithm conserves the most important properties of the logarithm, and show that important existing generalizations of the entropy are included as special cases in this two-parameter class.
Rumin, Tamanna; Hagino, Kouichi; Takigawa, Noboru
1999-01-01
We study fusion reactions of $^{16}$O with $^{154}$Sm, $^{186}$W and $^{238}$U at sub-barrier energies by a coupled-channels framework. We focus especially on the effects of $\\beta_{6}$ deformation and low-lying vibrational excitations of the target nucleus. It is shown that the inclusion of $\\beta_{6}$ deformation leads to a considerable improvement of the fit to the experimental data for all of these reactions. For the $^{154}$Sm and $^{238}$U targets, the octupole vibrati...
Construction of Miniversal Deformations of Lie Algebras
Fialowski, A; Fialowski, Alice; Fuchs, Dmitry
1999-01-01
We consider deformations of finite or infinite dimensional Lie algebras over a field of characteristic 0. There is substantial confusion in the literature if one tries to describe all the non-equivalent deformations of a given Lie algebra. It is known that there is in general no "universal" deformation of the Lie algebra L with a commutative algebra base A with the property that for any other deformation of L with base B there exists a unique homomorphism f: A -> B that induces an equivalent deformation. Thus one is led to seek a "miniversal" deformation. For a miniversal deformation such a homomorphism exists, but is unique only at the first level. If we consider deformations with base spec A, where A is a local algebra, then under some minor restrictions there exists a miniversal element. In this paper we give a construction of a miniversal deformation.
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.
A comparison of two magnetic ultra-cold neutron trapping concepts using a Halbach-octupole array
Leung, K; Martin, F; Rosenau, F; Simson, M; Zimmer, O
2015-01-01
This paper describes a new magnetic trap for ultra-cold neutrons (UCNs) made from a 1.2 m long Halbach-octupole array of permanent magnets with an inner bore radius of 47 mm combined with an assembly of superconducting end coils and bias field solenoid. The use of the trap in a vertical, magneto-gravitational and a horizontal setup are compared in terms of the effective volume and ability to control key systematic effects that need to be addressed in high precision neutron lifetime measurements.
Di-neutron correlation in soft octupole excitations of neutron-rich Ni isotopes beyond N=50
International Nuclear Information System (INIS)
We investigate the 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 that it strongly influences the di-neutron correlation. (author)
International Nuclear Information System (INIS)
A commercial purity aluminum was highly deformed by the accumulative roll-bonding (ARB) process and subsequently annealed. The specimens having various grain size distributions were obtained. In case of the specimen ARB-processed with lubrication, the specimens with mean grain size larger than 3?m showed continuous yielding. On the other hand, in case of the specimen ARB-processed without lubrication, the specimens with mean grain size larger than 3?m showed discontinuous yielding. It suggests that appearance of the yield-drop phenomena can not be decided by the mean grain size. In order to consider effect of grain size distribution, the volume fraction of grains was summed from coarser grains, and the grain size when the summed volume fraction reached 70%, d70% was estimated from the grain size distribution. it was found that d70% of specimens which showed continuous yielding were larger than 8 ?m while the specimens which showed discontinuous yielding were smaller than 6 ?m, regardless of the lubrication condition in the ARB process. The result suggests that the appearance of the yield-drop phenomena depend on d70%.
International Nuclear Information System (INIS)
The influence of austenization temperature on characteristics of hardness, ductility and magnetic properties of non-irradiated and irradiated with neutrons 12Cr18Ni10Ti steel was investigated. It was shown that a decrease in austenization temperature from 1150 to 1050 oC results in a negative impact on martensitic ???' transformation at cold deformation.
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.
Hamiel, Y.; Fialko, Y.
2005-12-01
We use interferometeric Synthetic Aperture Radar (InSAR) and Global Positioning System (GPS) observations to investigate the coseismic deformation induced by the 17 August 1999 Mw7.4 Izmit earthquake (Turkey). The InSAR data reveal small surface deformation anomalies away from the Izmit rupture, along nearby faults of the North Anatolian Shear Zone (Mudurnu Valley and Iznik faults). These deformation anomalies were interpreted as being due to retrograde triggered slip along these faults (Wright et al., 2001). We demonstrate that the inferred small-scale deformation is consistent with an elastic response of compliant fault zones to the stress field induced by the earthquake. The existence of such mechanically softened fault zones has been suggested based on field observations and studies of fault zone trapped waves as well as theoretical modeling of the fracturing process. We examine the spatial variations and the mechanical properties of the fault-zone using three-dimensional finite element models. In these models, we include compliant fault zones having various geometries and elastic properties, and apply stress changes deduced from the kinematic slip model of the Izmit earthquake. We find that the inferred fault zones have a characteristic width of a few kilometers, similar to fault zones discovered in the Eastern California Shear Zone using InSAR observations of coseismic deformation due to the 1992 Landers and 1999 Hector Mine Earthquakes. Our results suggest that such damage zones may be quite commonly associated with large crustal faults.
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.
International Nuclear Information System (INIS)
The deformation behavior at 25-300 C of rapidly solidified Al-3Li-0.6Co and Al-3Li-0.3Zr alloys was studied by tensile property measurements and transmission electron microscopic examination of dislocation substructures. In binary Al-3Li and Al-3Li-Co alloys, the modulus normalized yield stress increases with an increase in temperature up to 150 C and then decreases. The yield stress at 25 C of Al-3Li-0.3Zr alloys is 180-200 MPa higher than that of Al-3Li alloys. However, the yield stress of the Zr-containing alloy decreases drastically with increasing temperatures above 75 C. The short-term yield stresses at 100-200 C of the Al-3Li-based alloys are higher than that of the conventional high-temperature Al alloys. The temperature dependences of the flow stresses of the alloys were analyzed in terms of the magnitudes and temperature dependences of the various strengthening contributions in the two alloys. The dislocation substructures at 25-300 C were correlated with mechanical properties. 19 references
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.
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...
Magnetic octupole order in Ce0.7La0.3B6: A polarized neutron diffraction study
International Nuclear Information System (INIS)
Recently, in phase IV of CexLa1-xB6, weak but distinct superlattice reflections from the order parameter of phase IV have been detected by our unpolarized neutron scattering experiment [K. Kuwahara, K. Iwasa, M. Kohgi, N. Aso, M. Sera, F. Iga, J. Phys. Soc. Japan 76 (2007) 093702]. The scattering vector dependence of the intensity of superlattice reflections is quite unusual; the intensity is stronger for high scattering vectors. This result strongly indicates that the order parameter of phase IV is the magnetic octupole. However, the possibility that the observed superlattice reflections are due to lattice distortions could not be completely ruled out only on the basis of the unpolarized neutron scattering experiment. To confirm that the superlattice reflections are magnetic, therefore, we have performed a single crystal polarized neutron diffraction experiment on Ce0.7La0.3B6. The obtained result has clearly shown that the time reversal symmetry is broken by the order parameter of phase IV. This is further evidence for the magnetic octupole order in CexLa1-xB6.
International Nuclear Information System (INIS)
CERN is preparing for the construction of the Large Hadron Collider (LHC) to be installed in the LEP tunnel. The magnetic lattice of the LHC will consist of a ring of twin aperture dipoles and quadrupoles, connected electrically in series. To adjust the working point of the machine, so called tuning quadrupoles will be installed in pairs in each regular cell, next to the main quadrupoles. Also, to correct multipolar field errors in the LHC, an octupole correction winding is required near each lattice quadrupole. A nested construction of these two magnets is foreseen. As part of the LHC R and D program, CERN and ACICA (a group of five Spanish industries: Abengoz, Canzler, Indar, Cenemesa and AME; since June 1990 Cenemesa is part of ABB Spain), signed a common development agreement for the design, fabrication and testing of a prototype tuning quadrupole and octupole corrector. This paper describes the design of these magnets, giving details of magnetic and mechanical calculations, including results from existing and specially developed computer codes, and model work. Further, the construction procedures are described, including the facilities and tooling developed by ACICA for this work
Anisotropic Hydraulic Permeability Under Finite Deformation
ATESHIAN, GERARD A.; Weiss, Jeffrey A.
2010-01-01
The structural organization of biological tissues and cells often produces anisotropic transport properties. These tissues may also undergo large deformations under normal function, potentially inducing further anisotropy. A general framework for formulating constitutive relations for anisotropic transport properties under finite deformation is lacking in the literature. This study presents an approach based on representation theorems for symmetric tensor-valued functions and provides conditi...
Timothy Heaton
This site contains 24 questions on the topic of crustal deformation, which covers folding and faulting, rock behavior, geologic structures, and types of stress. This is part of the Principles of Earth Science course at the University of South Dakota. Users submit their answers and are provided immediate feedback.
Glukhova, Olga; Slepchenkov, Michael
2012-06-01
Electronic and adsorptive properties of deformed graphene are investigated in the current work. Armchair and zigzag nanoribbons are the subject of the study. The axial compression was a deforming load. A calculation method for the local stress field was developed. This method was based on the quantum model of the finite graphene nanoribbon and empirical calculation method of the single atom energy. The stress field of the deformed ribbon was calculated by means of the suggested methodology. The effects of the atomic grid curvature on the adsorptive capacity of graphene and the hydrogenation process was investigated by means of the developed method. The prediction of the appearance of defects on covalent C-C bond breakdown is also performed. PMID:22543701
Glukhova, Olga; Slepchenkov, Michael
2012-05-01
Electronic and adsorptive properties of deformed graphene are investigated in the current work. Armchair and zigzag nanoribbons are the subject of the study. The axial compression was a deforming load. A calculation method for the local stress field was developed. This method was based on the quantum model of the finite graphene nanoribbon and empirical calculation method of the single atom energy. The stress field of the deformed ribbon was calculated by means of the suggested methodology. The effects of the atomic grid curvature on the adsorptive capacity of graphene and the hydrogenation process was investigated by means of the developed method. The prediction of the appearance of defects on covalent C-C bond breakdown is also performed.
Cyclic Plastic Deformation and Welding Simulation:
Ten Horn, C. H. L. J.
2003-01-01
One of the concerns of a fitness for purpose analysis is the quantification of the relevant material properties. It is known from experiments that the mechanical properties of a material can change due to a monotonic plastic deformation or a cyclic plastic deformation. For a fitness for purpose analysis to be accurate in these cases, it has to take into account the current mechanical properties of the material. The problem is that the current properties may not always be known and retrieving ...
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.
International Nuclear Information System (INIS)
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.
Blinov, V. M.; Bannykh, O. A.; Lukin, E. I.; Kostina, M. V.; Blinov, E. V.
2014-11-01
The effect of the conditions of heat treatment and plastic deformation on the structure and the mechanical properties of low-carbon martensitic nickel steel (9 wt % Ni) with an overequilibrium nitrogen content is studied. The limiting strain to failure of 04N9Kh2A steel is found to be 40% at a rolling temperature of 20°C and 80% at a rolling temperature of 900°C. Significant strengthening of the steel (?0.2 = 1089 MPa) is obtained after rolling at a reduction of 40% at 20°C. The start and final temperatures of the ? ? ? transformation on heating and those of the ? ? ? transformation on cooling are determined by dilatometry. The specific features of the formation of the steel structure have been revealed as functions of the annealing and tempering temperatures. Electron-microscopic studies show that, after quenching from 850°C and tempering at 600°C for 1 h, the structure contains packet martensite with thin interlayers of retained austenite between martensite crystals. The strength of the nitrogen-bearing 04N9Kh2A steel after quenching from 850 and 900°C, cooling in water, and subsequent tempering at 500°C for 1 h is significantly higher than that of carboncontaining 0H9 steel used in cryogenic engineering.
Lefèvre, Victor; Lopez-Pamies, Oscar
2014-10-01
A solution is constructed for the homogenization problem of the elastic dielectric response of rubber filled with a random isotropic distribution of polydisperse spherical particles in the classical limit of small deformations and moderate electric fields. In this limit, the overall elastic dielectric response is characterized by five (two elastic, one dielectric, and two electrostrictive) effective constants. Explicit formulas are derived for these constants directly in terms of the corresponding constants describing the elastic dielectric response of the underlying rubber and the filler particles, as well as the concentration of particles. By means of comparisons with finite-element simulations, these formulas are shown to also be applicable to isotropic suspensions of monodisperse spherical particles, provided that the particle concentration is sufficiently away from percolation. With the aim of gaining physical insight into the extreme enhancement in electrostrictive properties displayed by emerging dielectric elastomer composites, specific results are examined for the case of suspensions wherein the rubber is incompressible and the particles are mechanically rigid and of infinite permittivity.
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.
Orlov, Dmitry; Pougis, Arnaud; Lapovok, Rimma; Toth, Laszlo S.; Timokhina, Ilana B.; Hodgson, Peter D.; Haldar, Arunansu; Bhattacharjee, Debashish
2013-09-01
IF steel sheets were processed by conventional symmetric and asymmetric rolling (ASR) at ambient temperature. The asymmetry was introduced in a geometric way using differential roll diameters with a number of different ratios. The material strength was measured by tensile testing and the microstructure was analyzed by optical and transmission electron microscopy as well as electron backscatter diffraction (EBSD) analysis. Texture was also successfully measured by EBSD using large surface areas. Finite element (FE) simulations were carried out for multiple passes to obtain the strain distribution after rolling. From the FE results, the velocity gradient along selected flow lines was extracted and the evolution of the texture was simulated using polycrystal plasticity modeling. The best mechanical properties were obtained after ASR using a roll diameter ratio of 2. The textures appeared to be tilted up to 12 deg around the transverse direction, which were simulated with the FE-combined polycrystal plasticity modeling in good agreement with measurements. The simulation work revealed that the shear component introduced by ASR was about the same magnitude as the normal component of the rolling strain tensor.
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)
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...
Lie algebras Classification, Deformations and Rigidity
Goze, M
2006-01-01
In the first section we recall some basic notions on Lie algebras. In a second time we study the algebraic variety of complex $n$-dimensional Lie algebras. We present different notions of deformations : Gerstenhaber deformations, pertubations, valued deformations and we use these tools to study some properties of this variety. Finaly we introduce the concept of rigidity and we present some results on the class of rigid Lie algebras.
Gbenebor, O. P.; Fayomi, O. S. I.; Popoola, A. P. I.; Inegbenebor, A. O.; Oyawale, F.
The response of 6063-type Al-Mg-Si alloy to deformation via extrusion was studied using tool steel dies with 15°, 30°, 45°, 60° and 75° entry angles. Compressive loads were subjected to each sample using the AVERY DENISON machine, adapted to supply a compressive load on the punch. The ability of the extrudate to absorb energy before fracture was calculated by integrating numerically the polynomial relationship between the compressive stress and sample strains. Strain rate was calculated for each specimen and the deformation zone length was mathematically derived from the die geometry to decipher its influence on both lateral and axial deformations. Results showed that extruding with a 15° die was the fastest as a result of the low flow stress encountered. Outstanding compressive strength, plastic deformation, strain rate and energy absorbing capacity were observed for the alloy extruded with a 75° die angle. Increase in die angles led to a decrease in deformation zone length and samples deformed more in the axial direction than in the lateral except for the 45o die which showed the opposite; the sample also showed the least ductility.
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)
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\\,$\\times \\mu_N$.
Distributed actuator deformable mirror
Bonora, Stefano
2010-01-01
In this paper we present a Deformable Mirror (DM) based on the continuous voltage distribution over a resistive layer. This DM can correct the low order aberrations (defocus, astigmatism, coma and spherical aberration) using three electrodes with nine contacts leading to an ideal device for sensorless applications. We present a mathematical description of the mirror, a comparison between the simulations and the experimental results. In order to demonstrate the effectiveness of the device we compared its performance with the one of a multiactuator DM of similar properties in the correction of an aberration statistics. At the end of the paper an example of sensorless correction is shown.
Regularized Harmonic Surface Deformation
Kozlov, Yeara; Esturo, Janick Martinez; Seidel, Hans-peter; Weinkauf, Tino
2014-01-01
Harmonic surface deformation is a well-known geometric modeling method that creates plausible deformations in an interactive manner. However, this method is susceptible to artifacts, in particular close to the deformation handles. These artifacts often correlate with strong gradients of the deformation energy.In this work, we propose a novel formulation of harmonic surface deformation, which incorporates a regularization of the deformation energy. To do so, we build on and e...
International Nuclear Information System (INIS)
Single-crystal aluminium nanowires under torsion are studied using molecular dynamics simulations based on the many-body tight-binding potential. The effects of temperature, loading rate and nanowire length are evaluated in terms of atomic trajectories, potential energy, von Mises stress, a centrosymmetry parameter, torque, shear modulus and radial distribution function. Simulation results clearly show that torsional deformation begins at the surface, extends close to the two ends and finally diffuses to the middle part. The critical torsional angle which represents the beginning of plastic deformation varies with different conditions. Before the critical torsional angle is reached, the potential energy and the torque required for the deformation of a nanowire significantly increase with the torsional angle. The critical torsional angle increases with increasing nanowire length and loading rate and decreasing temperature. The torque required for the deformation decreases and the shear modulus increases with increasing nanowire length. For higher temperatures and higher loading rates, torsional buckling more easily occurs at the two ends of a nanowire, whereas it occurs towards the middle part at or below room temperature with lower loading rates. Geometry instability occurs before material instability (buckling) for a long nanowire. (paper)
International Nuclear Information System (INIS)
Structure, microhardness and electrical resistivity of the Cu–0.18% Zr alloy after high pressure torsion (HPT) were investigated for different initial states (hot-pressed, annealed, quenched) and deformation schedules. It is shown that HPT leads to formation of submicrocrystalline structure with the grain size of 200–250 nm. Studying of electrical resistivity of the Cu–0.18% Zr alloy showed that during HPT it increases with increasing the strain in comparison with initial not deformed state. It can be connected with changes of grain and subgrain structure, and also with processes of dissolution of particles of the second phase Cu5Zr during deformation. Decreasing of electrical resistivity values of Cu–0.18% Zr alloy after HPT during heating in the temperatures range of 250–400 °C and preservation or increase of microhardness values in this temperature interval reveal aging processes with allocation of Cu5Zr particles and confirm the fact of partial supersaturation of solid solution of copper with zirconium during deformation. Application of quenching, HPT and subsequent aging allows to achieve the maximum strengthening of the alloy
Xue, W. X.; Yao, J. M.; Hagino, K.; Li, Z. P.; Mei, H.; Tanimura, Y.
2015-02-01
Background: The impurity effect of hyperons on atomic nuclei has received a renewed interest in nuclear physics since the first experimental observation of appreciable reduction of E 2 transition strength in low-lying states of the hypernucleus ?7Li . Many more data on low-lying states of ? hypernuclei will be measured soon for s d -shell nuclei, providing good opportunities to study the ? impurity effect on nuclear low-energy excitations. Purpose: We carry out a quantitative analysis of the ? hyperon impurity effect on the low-lying states of s d -shell nuclei at the beyond-mean-field level based on a relativistic point-coupling energy density functional (EDF), considering that the ? hyperon is injected into the lowest positive-parity (?s) and negative-parity (?p) states. Method: We adopt a triaxially deformed relativistic mean-field (RMF) approach for hypernuclei and calculate the ? binding energies of hypernuclei as well as the potential-energy surfaces (PESs) in the (? ,? ) deformation plane. We also calculate the PESs for the ? hypernuclei with good quantum numbers by using a microscopic particle rotor model (PRM) with the same relativistic EDF. The triaxially deformed RMF approach is further applied in order to determine the parameters of a five-dimensional collective Hamiltonian (5DCH) for the collective excitations of triaxially deformed core nuclei. Taking 25,27Mg ? and Si31? as examples, we analyze the impurity effects of ?s and ?p on the low-lying states of the core nuclei. Results: We show that ?s increases the excitation energy of the 21+ state and decreases the E 2 transition strength from this state to the ground state by 12 %to17 % . On the other hand, ?p tends to develop pronounced energy minima with larger deformation, although it modifies the collective parameters in such a way that the collectivity of the core nucleus can be either increased or decreased. Conclusions: The quadrupole deformation significantly affects the ? binding energies of deformed hypernuclei. A beyond-mean-field approach with the dynamical correlations due to restoration of broken symmetries and shape fluctuation is essential in order to study the ? impurity effect in a quantitative way.
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.
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 ...
Garkushin, G. V.; Razorenov, S. V.; Krasnoveikin, V. A.; Kozulin, A. A.; Skripnyak, V. A.
2015-02-01
The elastic limit and tensile strength of deformed magnesium alloys Ma2-1 with different structures and textures were measured with the aim of finding a correlation between the spectrum of defects in the material and the resistance to deformation and fracture under quasi-static and dynamic loading conditions. The studies were performed using specimens in the as-received state after high-temperature annealing and specimens subjected to equal-channel angular pressing at a temperature of 250°C. The anisotropy of strength characteristics of the material after shock compression with respect to the direction of rolling of the original alloy was investigated. It was shown that, in contrast to the quasi-static loading conditions, under the shock wave loading conditions, the elastic limit and tensile strength of the magnesium alloy Ma2-1 after equal-channel angular pressing decrease as compared to the specimens in the as-received state.
International Nuclear Information System (INIS)
Highlights: ? ECAP to four passes via route BC is combined with plane strain compression for 1050AA. ? Two loading schemes are employed in plane strain compression (PSC). ? Strain path change is employed to study microstructure and micro-texture. ? Prior texture to PSC influences the intensity of the developed rolling texture. ? Texture can be manipulated to produce a brass type texture in high SFE materials. -- Abstract: Electron back scattered diffraction (EBSD) was used to document the microstructure and microtexture developed due to cross deformation of commercial purity 1050 aluminum alloy. The material was first deformed in an equal channel angular pressing die (ECAP) to one up to four passes, via route Bc and then deformed in plane strain compression (PSC), in two different directions, to two axial true plastic strain values of 0.5 and 1.0. The study provides a documentation of the evolution of microstructure parameters namely; cell size, average misorientation angle, fraction of submicron cell size and fraction of high angle grain boundaries. These microstructure parameters were investigated on the plane normal to the loading direction in PSC (plane constituted by the rolling and transverse directions). These microstructure parameters were compared to those achieved due to the ECAP process only. The ideal rolling texture orientations are depicted and crystal orientation maps were generated. The spatial distribution of grains having these orientations are revealed through these maps. The fraction of the main texture components for a 15o spread around the specified orientations was experimentally calculated and a quantitative idea on the evolution of microtexture was also presented. Deformation path change was shown to be an effective tool for manipulating texture as well as microstructure.
Smirnova, N A; Mizusaki, T; Van Isacker, P
2000-01-01
The interrelation between the octupole phonon and the low-lying proton-neutron mixed-symmetry quadrupole phonon 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 sup + sub 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 gamma -unstable ones, are considered. We derive 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.
Third harmonic generation in organic octupole molecules with small absorption at 3?
International Nuclear Information System (INIS)
The nonlinear optical properties of 1,3,5-tricyano-2,4,6-tri (p-diethylaminostyryl) benzene (TTB) thin films have been measured by using third-harmonic generation (THG) at the fundamental wavelength of 1064 nm. By comparing the THG intensity with that of fused silica, we estimated the third-order electrical susceptibility of the organic film to be 1.2 X10-11 esu, which is about 400 times larger than that of fused silica glass. Due to the unique properties of the TTB films, such as anomalous dispersion and small re-absorption of the third harmonic wave, a thick film is expected to give a more efficient THG, which can be applied to ultrafast optical correlators.
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.
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:
Bojowald, Martin
2013-01-01
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 physical role, following from the relationship between canonical constraints of gravity with stress-energy components. The original deformation does not appear in momentum space and does not give rise to non-locality issues or problems with macroscopic objects. Contact with deformed special relativity may help to test loop quantum gravity or restrict its quantization ambiguities.
Deformation of Algebra Factorisations
Brzezinski, T
1999-01-01
A deformation theory of algebras which factorise into two subalgebras is studied. It is shown that the classification of deformations is related to the cohomology of a certain double complex reminiscent of the Gerstenhaber-Schack complex of a bialgebra.
Kommel, L.; Pokatilov, A.
2014-08-01
As-cast Cu-0.7wt% Cr and Cu-1.0wt% Cr alloys were subjected to equal-channel angular pressing (ECAP), hard cyclic viscoplastic (HCV) deformation and post deformation heat treatment for receiving an ultrafine grained material with a combination of high strength, good wear resistance and high electric conductivity. Samples from Cu-0.7wt% Cr alloy were processed up to six passes and Cu-1wt% Cr alloy samples were processed up to four passes of ECAP via Bc route. HCV deformation of samples was conducted by frequency of 0.5 Hz for 20 cycles at tension-compression strain amplitudes of +/-0.05%, +/-0.1%, +/-0.5%, +/-1% and +/-1.5%, respectively. During HCV deformation, as-cast Cu-0./wt% Cr alloy show fully viscoelastic behavior at strain/stress amplitude of +/-0.05% while ECAP processed material show the same behavior at strain amplitude of +/-0.1%. The Young modulus was increased from ~120 GPa up to ~150 GPa. The results illustrated that specific volume wear decrease with increasing of hardness but the measured coefficient of friction (COF ~ 0.6) was approximately the same for all samples at the end of wear testing. The hardness after ECAP for 6 passes by Bc route was 192HV0.1 and electric conduction 74.16% IACS, respectively. By this the as-cast Cu-0./wt% Cr alloy (heat treated at 1000 °C for 2h) has microhardness ~70HV0.1 and electrical conductivity of ~40% IACS. During aging at the temperatures in the interval of 250-550 °C for 1h the hardness and electrical conductivity were stabilized to mean values of 120+/-5HV0.1 and to 93.4+/-0.3% IACS, respectively. The hardness and electric conductivity took decrease by temperature increase over ~550 °C, respectively. The results of present experimental investigation show that UFG Cu- 0.7wt% Cr alloy with compare to Cu-1.0% Cr alloy is a highly electrical conductive and high temperature wear resistant material for using in electrical industry.
Nanoscale near-surface deformation in polymer nanocomposites
Energy Technology Data Exchange (ETDEWEB)
Yuan, Q. [Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504-4130 (United States); Ramisetti, N. [Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504-4130 (United States); Department of Chemical Engineering, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504-4130 (United States); Misra, R.D.K. [Center for Structural and Functional Materials, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504-4130 (United States); Department of Chemical Engineering, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70504-4130 (United States)], E-mail: dmisra@louisiana.edu
2008-05-15
The objective of the study is to understand the nanoscale near-surface deformation response of two polymer nanocomposite systems with significant differences in ductility during nanoscratching with a Berkovich indenter using a load of 1 mN and a scratch velocity of 1 {mu}m s{sup -1}. An accompanying objective is to investigate the commonality in surface deformation behavior between nano- and microscale deformation to reinforce the underlying fundamental principles governing surface deformation. An understanding of surface deformation response is accomplished through determination of physical and mechanical properties, structural characterization and electron microscopy analysis of surface deformation tracks and residual plastically deformed structures. The study suggests for the first time that the understanding derived from microscale surface deformation studies can be extended to nanoscale surface deformation. The microscale response in a polypropylene-based system is characterized by periodic multiple ripple-type deformation tracks that form via a mechanism identical to the periodic single-ripple-type tracks during nanoscale deformation. Similarly, in a less ductile polyethylene-based system, the periodic parabolic tracks and ironing mode of deformation during microscale deformation tend to be significantly reduced in intensity, with ironing being the primary deformation mechanism at the nanoscale. The surface deformation topography suggests that both micro- and nanoscale response is material specific. Additionally, the study suggests that reinforcement of polymers with nanoclay is a viable route to significantly decrease the susceptibility of polymeric materials to micro- and nanoscale deformation and can be discussed in terms of physical and mechanical properties of materials notably percentage crystallinity and elastic recovery.
Low-lying band structure and the onset of octupole collectivity in 150Nd
International Nuclear Information System (INIS)
Lying in a transitional region, the nucleus 150Nd is surprisingly poorly studied in comparison to the other neighboring isotones, such as 152Sm and 154Gd. There are serious discrepancies in the published work for states in 150Nd above 1150 keV in excitation. Also, a leading issue for the stable N=90 isotones is whether they are a manifestation of a critical-point phase transition or shape co-existence. A complete knowledge of the low-lying non-yrast states often plays a vital role in differentiating one phenomenon from the other. Thus, with the aim of obtaining a comprehensive picture of the properties of low-spin levels in 150Nd, a series of ?-ray spectroscopic experiments involving measurements of excitation functions, angular distributions, and ??? coincidences have been performed using the (n,n'?) reaction
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...
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.
Faye, Guillaume; Iyer, Bala R
2014-01-01
This paper is motivated by the need to improve the post-Newtonian (PN) amplitude accuracy of waveforms for gravitational waves generated by inspiralling compact binaries, both for use in data analysis and in the comparison between post-Newtonian approximations and numerical relativity computations. It presents: (i) the non-linear couplings between multipole moments of general post-Newtonian matter sources up to order 3.5PN, including all contributions from tails, tails-of-tails and the non-linear memory effect; and (ii) the source mass-type octupole moment of (non-spinning) compact binaries up to order 3PN, which permits to complete the expressions of the octupole modes (3,3) and (3,1) of the gravitational waveform to order 3.5PN. At this occasion we reconfirm by means of independent calculations our earlier results concerning the source mass-type quadrupole moment to order 3PN. Related discussions on factorized resummed waveforms and the occurence of logarithmic contributions to high order are also included.
Faye, Guillaume; Blanchet, Luc; Iyer, Bala R.
2015-02-01
This paper is motivated by the need to improve the post-Newtonian (PN) amplitude accuracy of waveforms for gravitational waves generated by inspiralling compact binaries, both for use in data analysis and in the comparison between post-Newtonian approximations and numerical relativity computations. It presents (i) the non-linear couplings between multipole moments of general post-Newtonian matter sources up to order 3.5PN, including all contributions from tails, tails-of-tails and the non-linear memory effect; and (ii) the source mass-type octupole moment of (non-spinning) compact binaries up to order 3PN, which permits completion of the expressions of the octupole modes (3,3) and (3,1) of the gravitational waveform to order 3.5PN. On this occasion we reconfirm by means of independent calculations our earlier results concerning the source mass-type quadrupole moment to order 3PN. Related discussions on factorized resummed waveforms and the occurence of logarithmic contributions to high order are also included.
International Nuclear Information System (INIS)
The structure and characteristic properties and predictions of the IBA in deformed nuclei are reviewed, and compared with experiment, in particular for 168Er. Overall, excellent agreement, with a minimum of free parameters (in effect, two, neglecting scale factors on energy differences), was obtained. A particularly surprising, and unavoidable, prediction is that of strong ? ? ? transitions, a feature characteristically absent in the geometrical model, but manifest empirically. Some discrepancies were also noted, principally for the K=4 excitation, and the detailed magnitudes of some specific B(E2) values. Considerable attention is paid to analyzing the structure of the IBA states and their relation to geometric models. The bandmixing formalism was studied to interpret both the aforementioned discrepancies and the origin of the ? ? ? transitions. The IBA states, extremely complex in the usual SU(5) basis, are transformed to the SU(3) basis, as is the interaction Hamiltonian. The IBA wave functions appear with much simplified structure in this way as does the structure of the associated B(E2) values. The nature of the symmetry breaking of SU(3) for actual deformed nuclei is seen to be predominantly ?K=0 mixing. A modified, and more consistent, formalism for the IBA-1 is introduced which is simpler, has fewer free parameters (in effect, one, neglecting scale factors on energy differences), is in at least as good agreement with experiment as the earlier formalism, contains a special case of the 0(6) limit which corresponds to that known empirically, and appears to have a close relationship to the IBA-2. The new formalism facilitates the construction of contour plots of various observables (e.g., energy or B(E2) ratios) as functions of N and chi/sub Q/ which allow the parameter-free discussion of qualitative trajectories or systematics
International Nuclear Information System (INIS)
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
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.
International Nuclear Information System (INIS)
Results of the first calculations aiming at determination of the exotic shape effects at large elongations are presented. After discussing some formal aspects of our generalised approach based on the deformed Woods-Saxon potential, the overall trends in the quantal (shell) effects leading to the deformation driving forces in terms of Y?=3,? multipole components are presented. Finally, the nuclei are identified in which (at least at a low spin limit) the predicted exotic shape effects should manifest themselves in the most pronounced way. 10 figs
Local and end deformation theorems for uniform embeddings
Yagasaki, Tatsuhiko
2013-01-01
A local deformation property for uniform embeddings in metric manifolds (LD) is formulated and its behaviour is studied in a formal view point. It is shown that any metric manifold with a geometric group action, typical metric spaces (Euclidean space, hyperbolic space and cylinders) and for \\kappa \\leq 0 the \\kappa-cone ends over any compact Lipschitz metric manifolds, all of them have the property (LD). We also formulate a notion of end deformation property for uniform embe...
Extended deformation functors, 1
Manetti, M
1999-01-01
We introduce a precise notion, in terms of few Schlessinger's type conditions, of extended deformation functors which is compatible with most of recent ideas in the Derived Deformation Theory (DDT) program and with geometric examples. With this notion we develop the (extended) analogue of Schlessinger and obstruction theories. The inverse mapping theorem holds for natural transformations of extended deformation functors and all such functors with finite dimensional tangent space are prorepresentable in the homotopy category.
Haghshenas-Haghighi, M.; Motagh, M.; Heim, B.; Sachs, T.; Kohnert, K.; Streletskiy, D. A.
2014-12-01
In this study, we assess seasonal subsidence/heaving due to thawing/freezing of the permafrost in Barrow (71.3 N, 156.5 W) at the northernmost point of Alaska. The topographic relief in this area is low. Thick Permafrost underlies the entire area, with large ice volumes in its upper layer. With a large collection of field measurements during the past decades at the Barrow Environmental Observatory (BEO), it is an ideal site for permafrost investigation. There are long term systematic geocryological investigations within the Global Terrestrial Network (GTN-P) of the Circumpolar Active Layer Monitoring (CALM) programme. We use 28 TerraSAR-X images, acquired between December 2012 and December 2013 and analyze them using the Small BAseline Subset (SBAS) technique to extract time-series of ground surface deformation. We also analyze hyperspectral images acquired by the airborne AISA sensor over Barrow area, within the AIRMETH2013 programme, to assess physical characteristics such as vegetation biomass and density, surface moisture, and water bodies. Finally, we combine the information derived from both InSAR and hyperspectral analysis, with field measurements to investigate the link between physical characteristics of the permafrost and surface displacement.
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...
International Nuclear Information System (INIS)
The waste packages, which Japan Atomic Energy Agency plans to dispose of, must be satisfied the technical standard specified by the Ordinance of Ministry of Economy, Trade and Industry. One of the technical standards is that the waste package must have enough strength to withstand the load when it is disposed of finally by burial method. Japan Atomic Energy Agency is required to prove the compliance of the waste package with the technical standard quantitatively because we shall obtain the confirmation of the regulatory authority. Accordingly the static load test was conducted to evaluate compressive strength and deformation performance of waste containers. The targets were 200 liter drum, concrete reinforced 200 liter drum, 200 liter drum containing cement solidified product and 1m3 cubic container which are expected to emplace into a concrete pit type disposal facility. Compression apparatuses which can imitate a loading condition in the facility were used. Based on the test result, 200 liter drum(M-class) has a minimum strength of 18kN and 1m3 cubic container has a maximum strength of 400kN. (author)
Nuclear deformation effects in the cluster radioactivity
International Nuclear Information System (INIS)
We investigate the influence of the nuclear deformation on the decay rates of some cluster emission processes. The interaction between the daughter and the cluster is given by a double folding potential including quadrupole and hexadecapole deformed densities of both fragments. The nuclear part of the nucleus-nucleus interaction is density dependent and at small distances a repulsive core in the potential will occur. In the frame of the WKB-approximation the assault frequency of the cluster will depend on the geometric properties of the potential pocket whereas the penetrability will be sensitive to changes in the barrier location. The results obtained in this paper point out that various combinations of cluster and daughter deformations may account for the measured values of the decay rate. The decay rates are however more sensitive to the changes in the daughter deformation due to the large mass asymmetry of the process. (author)
Deformation mechanisms of stable austenitic steels
International Nuclear Information System (INIS)
The presented thesis aims to give a contribution to the understanding of the basic mechanisms of plasticity in austenitic steel and of the outstanding mechanical properties. Structure analysis of deformed stable austenitic steel shows that it is deformation twinning which is an important mechanism of plasticity. The influence of deformation twinning increases with increased nitrogen content. Strength as well as work hardening rate increase strongly whereas toughness and ductility remain high. However, there is a transition from ductile to brittle behaviour which can be observed at low temperature, what in fact is atypical for face-centered cubic alloys. As a connection between experimentally (TEM) observed microstructures and the mechanical properties, simple structural models are developed. The main feature of the model is the disclination dipole representation of a deformation twin. The results are as follows: 1. It is the intersection of glide bands being the nucleation site of a deformation twin due to the local stress accumulation. 2. The accuracy of the disclination representation of a twin is satisfactory with respect to the presented analysis: the relative error of the stress fields is assumed to be less than 20 percent. 3. It is the cooperation between deformation twinning and glide which is responsible for high ductility. 4. The contribution of deformation twinning to the work hardening rate is controlled by the intersection of twins. Particularly, the work rsection of twins. Particularly, the work hardening rate increases with decreasing twin thickness. 5. Brittle fracture occurs whenever the stress field of a blocked deformation twin cannot be screened by other defects, i.e. if the density of mobile dislocations is low. With increasing nitrogen content the stacking fault energy decreases. (author) figs., tabs., refs
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
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.
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
Waldmann, S.
2014-09-01
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.
Directory of Open Access Journals (Sweden)
B. Chatterjee
2011-12-01
Full Text Available The present study considers finite element based contact analysis of an elastic-plastic axisymmetric hemisphere using ANSYS to study the effect of material properties under full stick contact condition. Results are compared with previous elastic-plastic models for perfect slip and full stick contact conditions. It is found that materials with modulus of elasticity to yield strength (E/Y ratio less than and greater than 300 show strikingly different contact behavior. When E/Y ratio is less than 300, contact load increases with the increase in modulus of elasticity whereas in elastic-plastic range, contact load decreases with the increase in yield strength.
International Nuclear Information System (INIS)
Metallographic analysis of the defects of the ''oblique cracks'' type on the surface of hot-rolled tubes of the 12Kh18N10T steel has been carried out. Recommended is the complex of mechanical properties and the structure factors (grain size) of conversion hot-rolled tubes, providing the combination of ductility and high rapture strength during rolling at pilger mills. At a grain size not coarser than number 5, a billet must have ?sub(T) 5>=40 %. Hot-rolled coarse-grained billet is not recommended for warm rolng because of high strain hardening
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.)
Deformation Investigation of Weld Based Rapid Prototyping
Directory of Open Access Journals (Sweden)
Abdul Samee
2014-05-01
Full Text Available This study investigates the deformation produced in the weld-based prototype and to optimize the welding parameters to minimize this deformation. Weld-based prototyping is a method to produce form-fit and near-net-shape or net shape prototypes. However, the large amount of heat exposure for the substrate plate and for previously built layers is one of the limitations of weld based prototyping. This causes high temperature gradient which results in deformation, residual stresses, warpage and poor surface quality. In this study a part is made by using welding by incremental layer buildup method. This yielded anisotropic material properties in the part with the non-homogeneous structure and porosity. In present study above mentioned problems were minimized by proper selection and optimizing the deposition parameters such as inter-pass cooling time, heat sink size, deposition speed, applying mechanical constraints and preheating. For analysis of present weld based prototype, experimental approach is adopted. In such developments, the phenomenon of deformation is very crucial to control. In this study a focus has been made on investigation of deformation produced and the parameters effecting this deformation.
Sonboli, Ali; Toroghinejad, Mohammad Reza; Edris, Hossein; Szpunar, Jerzy A.
2015-07-01
In the present work the influence of intermediate annealing and the strain path during a two-stage cold rolling on the microstructure and texture of a 1 wt% Si non-oriented electrical steel was investigated. Different processing conditions were tasted to develop favorable texture and better understand the relation between texture and important magnetic properties. The texture parameter (TP) was defined as "theta fiber/gamma fiber" ratio. The results showed that the samples with the highest TP have the lowest magnetic anisotropy. Also average magnetocrystalline energy was calculated and it was demonstrated that the lowest energy can be correlated with the highest "theta fiber/gamma fiber" ratio. Regardless of the condition of intermediate annealing process, the uni-directional rolling produced very similar texture parameter (~2). However, the cross rolled samples have very different texture parameters upon intermediate annealing. The cross rolled samples after intermediate annealing at 650 °C have the highest texture parameter (~3). The proposed thermo-mechanical processing allow diminishing gamma fiber which is deleterious for magnetic properties of non-oriented electrical steels.
International Nuclear Information System (INIS)
Molecular dynamics (MD) together with the modified analytical embedded atom method (MAEAM) is employed to study the alloying elements (Re, Ru, Co, and Ta) dependence of the elastic properties of L12-Ni3Al. The investigations indicate that the calculated elastic properties of Ni3Al are in reasonable agreement with the previous results. The substituting formation energies of the alloying elements in Ni3Al are calculated to determine the site preference. It is found out that Re, Ru, and Ta atoms prefer to occupy the Al sites, and the Co atom prefers to occupy the Ni site. Based on Re, Ru, and Ta substituting the 1st, 2nd, 3rd, and 4th nearest-neighbor atoms, we ascertain that the substituting manners of these alloying elements have a decisive effect on the bulk modulus and the local crystal lattice of Ni3Al. Moreover, for Re, the bonding interaction plays a predominant role in the improvement in the bulk modulus of Ni3Al, whereas the size effect of Ru and Ta on the improvement in the bulk modulus is more obvious. Finally, the potential reasons of which the alloying elements enhance the bulk modulus are discussed in details
International Nuclear Information System (INIS)
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
Deformational characteristics of thermoplastic elastomers
Indukuri, Kishore K.
This thesis focuses primarily on the structure-property relationships of poly (styrene-ethylene-butylene-styrene) triblock copolymer TPEs. First evidence for strain-induced crystallization occurring in certain SEBS block copolymers has been established using unique techniques like deformation calorimetry, combined in-situ small angle X-ray and wide angle X-ray diffraction (SAXD/WAXD). Also the ramifications of such strain-induced crystallization on the mechanical properties like cyclic hysteresis, stress relaxation/creep retention of these SEBS systems have been studied. In addition, the structural changes in the morphology of these systems on deformation have been investigated using combined SAXD/WAXD setup. Small angle X-ray diffraction probed the changes at the nano-scale of polystyrene (PS) cylinders, while wide angle X-ray diffraction probed the changes at molecular length scales of the amorphous/crystalline domains of the elastomeric mid-block in these systems. New structural features at both these length scales have been observed and incorporated into the overall deformation mechanisms of the material. Continuous processing techniques like extrusion have been used to obtain ultra long-range order and orientation in these SEBS systems. Thus well ordered crystal like hexagonal packing of cylinders, where in each element in this hexagonal lattice can be individually addressed without any grain boundaries can be realized using these robust techniques. The effect of long-range order/orientation on the mechanical properties has been studied. In addition, these well ordered systems serve as model systems for evaluating deformation mechanisms of these SEBS systems, where the relative contributions of each of the phases can be estimated. EPDM/i-PP thermoplastic vulcanizates (TPVs) have micron size scale phase separated morphologies of EPDM rubber dispersed in a semicrystalline i-PP matrix as a result of the dynamic vulcanization process. Confocal microscopy studies, along with scanning electron microscopy (SEM) studies show that the morphology of these EPDM/i-PP systems resembles a microcellular "filled" foam in which i-PP occupies the strut regions and EPDM the inner core. Based on this, an analytical model has been developed that takes into account composition information, molecular weight, cure state and morphology into account.
Kanada-En'yo, Y.
2004-01-01
Systematic analysis of the deformations of proton and neutron densities in even-even C isotopes was done based on the method of antisymmetrized molecular dynamics. The $E2$ transition strength was discussed in relation to the deformation. We analyze the $B(E2;2^+_1\\to 0^+_1)$ in $^{16}$C, which has been recently measured to be abnormally small. The results suggest the difference of the deformations between proton and neutron densities in the neutron-rich C isotopes. It was f...
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)
Impact between deformable bodies
International Nuclear Information System (INIS)
The bodies are represented by constant strain finite elements so that the element internal forces can most easily be calculated, especially after yielding has taken place when the stress and strain increments are related in accordance with the Prandtl-Reuss theory. In the case of axisymmetrical problems triangular axisymmetrical elements are used whose properties are approximately calculated by sampling at the centroid of the cross-section. The external applied forces arise from the impact and contact forces at the interfaces, and the inertia forces are obtained from lumped mass matrices. The equation of motion is solved by a central difference explicit scheme in small incremental time steps. This enables the stress propagation as well as the history of plastic deformation in the bodies to be traced throughout the duration of impact. The material law is idealised to be piecewise linear, with an initial elastic portion followed by one linear hardening segment. Perfect plasticity (zero hardening) can also be allowed. A simple procedure deals with the case of loading from an elastic initial state to a final plastic state in one time step. The program has been applied to the investigation of a number of axisymmetrical problems. The three dimensional version of the program is now being coded. Examples: impact of a falling fuel stringer in a storage tube; impact of a cylinder on a rigid boundary; supported circular plate loaded by uniformly distributed impulses; impact of aniformly distributed impulses; impact of a non-return valve in a pipe rupture; impact of a cylindrical fuel-waste flask; impact of a conical missile on a rigid surface. (orig./HP)
Deformations of the antibracket
Konstein, S. E.; Tyutin, I. V.
2005-01-01
We consider antiPoisson superalgebras realized on the smooth Grassmann-valued functions with compact supports in R^n and with the grading inverse to Grassmanian parity. The deformations of these superalgebras and their central extensions are found.
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 ...
Shirzad, Khalid; Kiesau, Carter D; DeOrio, James K; Parekh, Selene G
2011-08-01
Lesser toe deformities are caused by alterations in normal anatomy that create an imbalance between the intrinsic and extrinsic muscles. Causes include improper shoe wear, trauma, genetics, inflammatory arthritis, and neuromuscular and metabolic diseases. Typical deformities include mallet toe, hammer toe, claw toe, curly toe, and crossover toe. Abnormalities associated with the metatarsophalangeal (MTP) joints include hallux valgus of the first MTP joint and instability of the lesser MTP joints, especially the second toe. Midfoot and hindfoot deformities (eg, cavus foot, varus hindfoot, valgus hindfoot with forefoot pronation) may be present, as well. Nonsurgical management focuses on relieving pressure and correcting deformity with various appliances. Surgical management is reserved for patients who fail nonsurgical treatment. Options include soft-tissue correction (eg, tendon transfer) as well as bony procedures (eg, joint resection, fusion, metatarsal shortening), or a combination of techniques. PMID:21807918
Directory of Open Access Journals (Sweden)
W. Ozgowicz
2009-09-01
Full Text Available Purpose: The aim of the paper is to determine the influence of temperature of plastic deformation on the structure and mechanical properties of copper alloy of the CuCo2Be and CuCo1Ni1Be during a tensile test applied on electrodes to welders.Design/methodology/approach: The tensile test of the investigated copper alloys was realized in the temperature range of 20-800°C with a strain rate of 1.2•10-3s–1 on the universal testing machine. Metallographic observations of the structure were carried out on a light microscope and the fractographic investigation of fracture on an electron scanning microscope.Findings: The mechanical properties of alloys as well as the range of occurrence of the Portevin - Le Chatelier (PLC phenomenon was determined on the basis of F-?L curves formed by tensile tests; however the character of fracture during the break of the samples was defined on the basis of fractographic investigations.Research limitations/implications:Practical implications: In result of tensile tests of copper alloys it has been found that the PLC effect occurs in both alloys in the temperature range of 150-350°C. However, the ductility minimum temperature of the alloys equals about 500°C. At the temperature of stretching of about 450°C the investigated copper alloys show maximum strength values.Originality/value: The type of ”teething” on the load - displacement curves was defined, according to the classification received in literature. The dependence ?kr = f(t was marked too.
Arratia, Oscar; Martin, Miguel A; Olmo, Mariano A.
1998-01-01
We review several procedures of quantization formulated in the framework of (classical) phase space M. These quantization methods consider Quantum Mechanics as a "deformation" of Classical Mechanics by means of the "transformation" of the commutative algebra of smooth functions on M in a new non-commutative algebra. These ideas lead in a natural way to Quantum Groups as deformation (or quantization, in a broad sense) of Poisson-Lie groups, which is also analysed here.
Deformed logarithms and entropies
Kaniadakis, G.; M. Lissia; Scarfone, A. M.
2004-01-01
By solving a differential-functional equation inposed by the MaxEnt principle we obtain a class of two-parameter deformed logarithms and construct the corresponding two-parameter generalized trace-form entropies. Generalized distributions follow from these generalized entropies in the same fashion as the Gaussian distribution follows from the Shannon entropy, which is a special limiting case of the family. We determine the region of parameters where the deformed logarithm co...
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.
Versal deformations of Leibniz algebras
Fialowski, A; Mukherjee, G; Fialowski, Alice; Mandal, Ashis; Mukherjee, Goutam
2007-01-01
In this work we consider deformations of Leibniz algebras over a field of characteristic zero. The main problem in deformation theory is to describe all non-equivalent deformations of a given object. We give a method to solve this problem completely, namely work out a construction of a versal deformation for a given Leibniz algebra, which induces all non-equivalent deformations and is unique on the infinitesimal level.
Highly deformable liquid-state heterojunction sensors
Ota, Hiroki; Chen, Kevin; Lin, Yongjing; Kiriya, Daisuke; Shiraki, Hiroshi; Yu, Zhibin; Ha, Tae-Jun; Javey, Ali
2014-09-01
Mechanically deformable devices and sensors enable conformal coverage of electronic systems on curved and soft surfaces. Sensors utilizing liquids confined in soft templates as the sensing component present the ideal platform for such applications, as liquids are inherently more deformable than solids. However, to date, liquid-based devices have been limited to metal lines based on a single-liquid component given the difficulty in the fabrication of liquid-based junctions due to intermixing. Here, we demonstrate a robust platform for the fabrication of liquid–liquid ‘heterojunction’ devices, presenting an important advancement towards the realization of liquid-state electronic systems. The device architecture and fabrication scheme we present are generic for different sensing liquids, enabling demonstration of sensors responsive to different stimuli. As a proof of concept, we demonstrate temperature, humidity and oxygen sensors by using different ionic liquids, exhibiting high sensitivity with excellent mechanical deformability arising from the inherent property of the liquid phase.
Deformed relativistic Hartree Bogoliubov theory in continuum
Li, Lulu; Ring, P; Zhao, En-Guang; Zhou, Shan-Gui
2012-01-01
A deformed relativistic Hartree Bogoliubov (RHB) theory in continuum is developed aiming at a proper description of exotic nuclei, particularly those with a large spatial extension. In order to give an adequate consideration of both the contribution of the continuum and the large spatial distribution in exotic nuclei, the deformed RHB equations are solved in a Woods-Saxon (WS) basis in which the radial wave functions have a proper asymptotic behavior at large distance from the nuclear center. This is crucial for the proper description of a possible halo. The formalism of deformed RHB theory in continuum is presented. A stable nucleus, 20Mg and a weakly-bound nucleus, 42Mg, are taken as examples to present numerical details and to carry out necessary numerical checks. In addition, the ground state properties of even-even magnesium isotopes are investigated. The generic conditions of the formation of a halo in weakly bound deformed systems and the shape of the halo in deformed nuclei are discussed. We show that...
Deformation texture in Fe-Co-V magnetic alloy
International Nuclear Information System (INIS)
The texture produced during cold rolling of Fe-49Co-8V magnetic alloy was studied by X-ray diffraction technique. The alloy contains 34% FCC austenite and 66% BCC martensite phase. The austenite phase was mechanically unstable and can be transformed to the martensite phase by 30% deformation. The austenite show the cube (001) and shear (001) texture components prior to deformation which become weak with the degree of deformation due to decrease in volume percentage of the austenite content. The martensite phase produced the weak (001), (100) and (111) orientations in un-deformed state that remains stable and become strong after 90% cold rolling due to strain hardening of the alloy. The microstructural studies reveled that deformation bands appeared in 30% deformed samples. The severity of these deformation bands increases with the degree of cold rolling and reaches to maximum in 90% deformed samples. The maximum magnetic properties obtained in 90% cold deformed sample were as: H/sub c/= 30.70e, B/sub r/4.8kG and B/sub s/ 5.6kG . (author)
Autogenous Deformation of Concrete
DEFF Research Database (Denmark)
2004-01-01
Autogenous deformation of concrete can be defined as the free deformation of sealed concrete at a constant temperature. A number of observed problems with early age cracking of high-performance concretes can be attributed to this phenomenon. During the last 10 years , this has led to an increased focus on autogenous deformation both within concrete practice and concrete research. Since 1996 the interest has been significant enough to hold international, yearly conferences entirely devoted to this subject. The papers in this publication were presented at two consecutive half-day sessions at the American Concrete Institute’s Fall Convention in Phoenix, Arizona, October 29, 2002. All papers have been reviewed according to ACI rules. This publication, as well as the sessions, was sponsored by ACI committee 236, Material Science of Concrete. The 12 presentations from 8 different countries indicate the broad, global research efforts dealing with autogenous deformation, and the good attendance at the convention – an audience of up to 90 people – shows that this interest is shared by the general concrete community. Attendees left with an understanding of the complexity of the autogenous deformation of concrete – the sessions showed that cooperation and more research are needed. At the ACI 2002 Fall Convention, the international materials research organization, RILEM, took steps to promote further research and cooperation within this area. Two technical committees held initial meetings with the involvement of many ACI members. More collaborative research will be carried out!
Crustal deformation and earthquakes
Cohen, S. C.
1984-01-01
The manner in which the Earth's surface deforms during the cycle of stress accumulation and release along major faults is investigated. In an investigation of the crustal deformation associated with a thin channel asthenosphere displacements are reduced from those computed for a half space asthenosphere. A previous finding by other workers that displacements are enhanced when flow is confined to a thin channel is based on several invalid approximations. The major predictions of the finite element model are that the near field postseismic displacements and strain rates are less than those for a half space asthenosphere and that the postseismic strain rates at intermediate distances are greater (in magnitude). The finite width of the asthenosphere ceases to have a significant impact on the crustal deformation pattern when its magnitude exceeds about three lithosphere thicknesses.
Deformations and Geometric Cosets
Petropoulos, P. Marios
2004-01-01
I review some marginal deformations of SU(2) and SL(2,R) Wess-Zumino-Witten models, which are relevant for the investigation of the moduli space of NS5/F1 brane configurations. Particular emphasis is given to the asymmetric deformations, triggered by electric or magnetic fluxes. These exhibit critical values, where the target spaces become exact geometric cosets such as S2 = SU(2)/U(1) or AdS2 = SL(2,R)/U(1)-space. I comment about further generalizations towards the appearan...
Deformation in nanocrystalline metals
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Helena Van Swygenhoven
2006-05-01
Full Text Available It is now possible to synthesize polycrystalline metals made up of grains that average less than 100 nm in size. Such nanocrystalline metals contain a significant volume fraction of interfacial regions separated by nearly perfect crystals. The small sizes involved limit the conventional operation of dislocation sources and thus a fundamental question arises: how do these materials deform plastically? We review the current views on deformation mechanisms in nanocrystalline, face-centered cubic metals based on insights gained by atomistic computer simulations. These insights are discussed with reference to recent striking experimental observations that can be compared with predictions made by the simulations.
Deformation in the continental lithosphere
The Physical Properties of Earth Materials Committee, a technical committee of AGU's Tectonophysics Section, is organizing a dinner/colloquium as part of the Fall Meeting in San Francisco, Calif. This event will be held Monday, December 3rd, in the Gold Rush Room of the Holiday Inn Golden Gateway Hotel at 1500 Van Ness St. There will be a no-host bar from 6:30 to 7:30 P.M., followed by dinner from 7:30 to 8:30 P.M. Paul Tapponnier will deliver the after-dinner talk, “Large-Scale Deformation Mechanisms in the Continental Lithosphere: Where Do We Stand?” It will start at 8:30 P.M. and a business meeting will follow at 9:30 P.M.
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...
Unimorph-type deformable mirror for cryogenic telescopes
Reinlein, Claudia; Goy, Matthias; Lange, Nicolas; Kinast, Jan
2014-07-01
Deformable mirrors can be used in cryogenic instruments to compensate for temperature-induced deformations. A unimorph-type deformable mirror consists of a mirror substrate and a piezoelectric layer bonded on substrates rear surface. A challenge in the design of the deformable mirror is the lack of knowledge about material properties. Therefore, we measured the coefficient of thermal expansion (CTE) of the substrate material TiAl6V4 between 295 K and 86 K. The manufactured mirror is characterized by an adaptive optical measurement setup in front of a test cryostat. The measured mirror deformations are feedback into a finite element model to calculate the CTE of the piezoelectric layer. We compare our obtained results to other published CTE-values for the piezoelectric material PIC151.
Deformed Covariant Quantum Phase Spaces as Hopf Algebroids
Lukierski, Jerzy
2015-01-01
We consider the general D=4 (10+10)-dimensional kappa-deformed quantum phase space as given by Heisenberg double \\mathcal{H} of D=4 kappa-deformed Poincare-Hopf algebra H. The standard (4+4) -dimensional kappa - deformed covariant quantum phase space spanned by kappa - deformed Minkowski coordinates and commuting momenta generators ({x}_{\\mu },{p}_{\\mu }) is obtained as the subalgebra of \\mathcal{H}. We study further the property that Heisenberg double defines particular quantum spaces with Hopf algebroid structure. We calculate by using purely algebraic methods the explicite Hopf algebroid structure of standard kappa - deformed quantum covariant phase space in Majid-Ruegg bicrossproduct basis. The coproducts for Hopf algebroids are not unique, determined modulo the coproduct gauge freedom. Finally we consider the interpretation of the algebraic description of quantum phase spaces as Hopf bialgebroids.
A Theoretical Study of the Magnetically Deformed Inner Crust Matter of Magnetars
Ghosh, Arpita
2011-01-01
We have studied various physical properties of magnetically deformed atoms and the associated matter, replacing the atoms by the deformed Wigner-Seitz (WS) cells at the crustal region of strongly magnetized neutron stars (magnetars). A relativistic version of Thomas-Fermi (TF) model in presence of strong magnetic field in cylindrical coordinates is used to study the properties of such matter.
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
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
Rapid collision detection for deformable objects using inclusion-fields applied to cloth simulation
Directory of Open Access Journals (Sweden)
Asma A. ElBadrawy
2012-07-01
Full Text Available We introduce an inclusion-field technique for fast detection of collisions between a highly deformable object and another object with limited deformations. We mainly target the cloth simulation application where cloth (highly deformable collides with deforming skin of a moving human model (has limited deformation as skin stretches and compacts within finite spacial and temporal limits specified by the bending angle and speed. Our technique intermixes concepts from space voxelization and distance fields to make use of the limited deformation nature of human skin. The technique works by discretizing the space containing the object into cells, and giving each cell an inclusion property. This property specifies whether this cell lies inside, outside, or on the surface of the deforming object. As the object deforms, the cells’ inclusion properties are updated to maintain the correctness of the collision detection process. We tested our technique on a generally deforming Bezier surface, and on cloth simulation to detect collisions between cloth and several articulated and deforming human body parts. Results showed that the inclusion field allows real-time collision detection between cloth and limited deformable objects on a standard PC. The technique is simple and easy to implement.
Nonperturbative effects in deformation quantization
Periwal, V
2000-01-01
The Cattaneo-Felder path integral form of the perturbative Kontsevich deformation quantization formula is used to explicitly demonstrate the existence of nonperturbative corrections to na\\"\\i ve deformation quantization.
$\\kappa$-deformed Dirac Equation
Harikumar, E.; Sivakumar, M.; Srinivas, N.
2009-01-01
We construct a Dirac equation in $\\kappa$-Minkowski spacetime and analyse its implications. This $\\kappa$-deformed Dirac equation is expanded as a power series involving derivatives with respect to commutative coordinates and the deformation parameter, $a$. We show that the $\\kappa$-deformation breaks the charge conjugation invariance but preserves parity and time reversal. We then study how the Hydrogen atom spectrum is modified due to the $\\kappa$-deformation, applying per...
Deformations of Lie 2-algebras
Liu, Zhangju; Sheng, Yunhe; Zhang, Tao
2014-12-01
In this paper, we consider deformations of Lie 2-algebras via the cohomology theory. We prove that a 1-parameter infinitesimal deformation of a Lie 2-algebra g corresponds to a 2-cocycle of g with the coefficients in the adjoint representation. A Nijenhuis operator on a Lie 2-algebra is introduced to describe trivial deformations. We also study abelian extensions of Lie 2-algebras from the viewpoint of deformations of semidirect product Lie 2-algebras.
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)
Deformed exterior algebra, quons and their coherent states
El-Baz, M
2002-01-01
We review the notion of the deformation of the exterior wedge product. This allows us to construct the deformation of the algebra of exterior forms over a vector space and also over an arbitrary manifold. We relate this approach to the generalized statistics and we study quons, as a particular case of these generalized statistics. We also give their statistical properties. A large part of the work is devoted to the problem of constructing coherent states for the deformed oscillators. We give a review of all the approaches existing in the literature concerning this point and enforce it with many examples.
Deformed exterior algebra, Quons and related Coherent States
Baz, M E
2003-01-01
We review the notion of the deformation of the exterior wedge product. This allows us to construct the deformation of the algebra of exterior forms over a vector space and also over an arbitrary manifold. We relate this approach to the generalized statistics. we study quons, as a particular case of these generalized statistics. We also give their statistical properties. A large part of the work is devoted to the problem of constructing coherent states for the deformed oscillators. we give a review of all the approaches existing in the literature concerning this point and enforce it with many examples.
Deformed exterior algebra, quons and their coherent states
International Nuclear Information System (INIS)
We review the notion of the deformation of the exterior wedge product. This allows us to construct the deformation of the algebra of exterior forms over a vector space and also over an arbitrary manifold. We relate this approach to the generalized statistics and we study quons, as a particular case of these generalized statistics. We also give their statistical properties. A large part of the work is devoted to the problem of constructing coherent states for the deformed oscillators. We give a review of all the approaches existing in the literature concerning this point and enforce it with many examples. (author)
Deformation of MgO by Vickers microindentation tests
Giberteau, F.; Dominguez-rodriguez, A.; Ma?rquez, R.; Castaing, J.
1982-01-01
Vickers microhardness tests have been performed at room temperature on (100), (110), and (111) MgO faces for various orientations of the pyramid diagonal. The indentations may be deformed probably because of cracking. Comparisons have been made with NiO and CoO which have the same crystal structure, but different plastic and fracture properties. One must be cautious when considering hardness anisotropy which is usually explained by plastic deformation. Dislocation rosette anisotropy is small,...
Deformation and scattering in graphene over substrate steps
Low, Tony; Perebeinos, Vasili; Tersoff, Jerry; Avouris, Phaedon
2012-01-01
The electrical properties of graphene depend sensitively on the substrate. For example, recent measurements of epitaxial graphene on SiC show resistance arising from steps on the substrate. Here we calculate the deformation of graphene at substrate steps, and the resulting electrical resistance, over a wide range of step heights. The elastic deformations contribute only a very small resistance at the step. However, for graphene on SiC(0001) there is strong substrate-induced ...
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)
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...
Deformation, Vibration, Buckling of Continuum Nanotorus
International Nuclear Information System (INIS)
A nanotorus is theoretically described as carbon nanotube bent into a torus (doughnut shape). Nanotori are predicted to have many unique properties, such as magnetic moments 1000 times larger than previously expected for certain specific radii. Its properties vary widely depending on radius of the torus and radius of the tube. Here, we developed a continuum model of nanotorus and obtained a closed form solutions for nanotorus deformation, vibration, and buckling and embedded in an elastic medium. The nanotorus is considered as a continuum model.
Towards noncommutative ?-deformed field theory
International Nuclear Information System (INIS)
The ?-deformation of local quantum free fields originates from two sources: noncommutativity of space-time (?* product) and the ?-deformation of field oscillators algebra (?-statistics). We introduce new ?-deformed algebra of field oscillators and we relate it with ?* product of space-time fields. We obtain as the field commutator the deformed Pauli-Jordan function, with ?-deformed mass-shell, which provides the model of ?-causal function. We show that in ?-Fock space one can introduce the basis describing n-particle states with four momenta added in accordance with classical Abelian addition law. (author)
Cathodoluminescence of natural, plastically deformed pink diamonds.
Gaillou, E; Post, J E; Rose, T; Butler, J E
2012-12-01
The 49 type I natural pink diamonds examined exhibit color restricted to lamellae or bands oriented along {111} that are created by plastic deformation. Pink diamonds fall into two groups: (1) diamonds from Argyle in Australia and Santa Elena in Venezuela are heavily strained throughout and exhibit pink bands alternating with colorless areas, and (2) diamonds from other localities have strain localized near the discrete pink lamellae. Growth zones are highlighted by a blue cathodoluminescence (CL) and crosscut by the pink lamellae that emit yellowish-green CL that originates from the H3 center. This center probably forms by the recombination of nitrogen-related centers (A-aggregates) and vacancies mobilized by natural annealing in the Earth's mantle. Twinning is the most likely mechanism through which plastic deformation is accommodated for the two groups of diamonds. The plastic deformation creates new centers visible through spectroscopic methods, including the one responsible for the pink color, which remains unidentified. The differences in the plastic deformation features, and resulting CL properties, for the two groups might correlate to the particular geologic conditions under which the diamonds formed; those from Argyle and Santa Elena are deposits located within Proterozoic cratons, whereas most diamonds originate from Archean cratons. PMID:23217341
Modelling Prostate Deformation: SOFA versus Experiments
Directory of Open Access Journals (Sweden)
Pedro Moreira
2013-07-01
Full Text Available Needle insertion procedures are commonly used to treat and to diagnose prostate cancer. Surgical simulation systems can be used to estimate prostate deformation during pre- and intra-operative needle insertion planning. Such systems require a model that can accurately predict the prostate deformation in real time. In this study, we present a prostate model that incorporates the anatomy of the male pelvic region. The model is used to predict the prostate deformation during needle insertion and it is implemented in the Simulation Open Framework Architecture (SOFA. SOFA simulations are compared with experimental results for two scenarios: indentation and needle insertion. An experimental phantom is developed using anatomically accurate magnetic resonance images and populated with elasticity properties obtained from ultrasound-based Acoustic Radiation Force Impulse imaging technique. Markers are placed on the phantom surface to identify the deformation during indentation experiments. The root mean square error (RMSE obtained in indentation experiments is 0.36 mm. During the needle insertion, the needle tip position is used to validate the model. The SOFA simulation resulted in a RMSE of 0.14 mm. The results of this study demonstrate that SOFA is a feasible option to be used in surgical simulations for pre-operative planning and training.
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.
de Miranda, Joachim R; Genersch, Elke
2010-01-01
Deformed wing virus (DWV; Iflaviridae) is one of many viruses infecting honeybees and one of the most heavily investigated due to its close association with honeybee colony collapse induced by Varroadestructor. In the absence of V.destructor DWV infection does not result in visible symptoms or any apparent negative impact on host fitness. However, for reasons that are still not fully understood, the transmission of DWV by V.destructor to the developing pupae causes clinical symptoms, including pupal death and adult bees emerging with deformed wings, a bloated, shortened abdomen and discolouration. These bees are not viable and die soon after emergence. In this review we will summarize the historical and recent data on DWV and its relatives, covering the genetics, pathobiology, and transmission of this important viral honeybee pathogen, and discuss these within the wider theoretical concepts relating to the genetic variability and population structure of RNA viruses, the evolution of virulence and the development of disease symptoms. PMID:19909976
Deformed Supersymmetric Mechanics
Ivanov, E
2013-01-01
Motivated by a recent interest in curved rigid supersymmetries, we construct a new type of N=4, d=1 supersymmetric systems by employing superfields defined on the cosets of the supergroup SU(2|1). The relevant worldline supersymmetry is a deformation of the standard N=4, d=1 supersymmetry by a mass parameter m. As instructive examples we consider, at the classical and quantum levels, the models associated with the supermultiplets (1,4,3) and (2,4,2) and find out interesting interrelations with some previous works on non-standard d=1 supersymmetry. In particular, the d=1$ systems with "weak supersymmetry" are naturally reproduced within our SU(2|1) superfield approach as a subclass of the (1,4,3) models. A generalization to the N=8, d=1$ case implies the supergroup SU(2|2) as the candidate deformed worldline supersymmetry.
Energy Technology Data Exchange (ETDEWEB)
Winn, E.J.; Chen, I.-W. [Pennsylvania Univ., Philadelphia, PA (United States). Dept. of Materials Science and Engineering
2000-07-01
The inherent instability, under deformation, of the interface between two materials with dissimilar flow stresses is exploited in the production of composites with structures ranging from laminar to wood-like in texture. Conventional tape-casting is used to give materials with a flow stress controlled only by the binder/plasticiser ratio and the temperature. Repeated deformation of layered materials, by folding and warm-pressing, causes the harder phase to break up into discrete, elongated regions. Composites with a dense ZrO{sub 2} matrix and porous Al{sub 2}O{sub 3} inter layers exhibited graceful failure and crack deflection. (orig.)
Deformation of wrinkled graphene.
Li, Zheling; Kinloch, Ian A; Young, Robert J; Novoselov, Kostya S; Anagnostopoulos, George; Parthenios, John; Galiotis, Costas; Papagelis, Konstantinos; Lu, Ching-Yu; Britnell, Liam
2015-04-28
The deformation of monolayer graphene, produced by chemical vapor deposition (CVD), on a polyester film substrate has been investigated through the use of Raman spectroscopy. It has been found that the microstructure of the CVD graphene consists of a hexagonal array of islands of flat monolayer graphene separated by wrinkled material. During deformation, it was found that the rate of shift of the Raman 2D band wavenumber per unit strain was less than 25% of that of flat flakes of mechanically exfoliated graphene, whereas the rate of band broadening per unit strain was about 75% of that of the exfoliated material. This unusual deformation behavior has been modeled in terms of mechanically isolated graphene islands separated by the graphene wrinkles, with the strain distribution in each graphene island determined using shear lag analysis. The effect of the size and position of the Raman laser beam spot has also been incorporated in the model. The predictions fit well with the behavior observed experimentally for the Raman band shifts and broadening of the wrinkled CVD graphene. The effect of wrinkles upon the efficiency of graphene to reinforce nanocomposites is also discussed. PMID:25765609
Deformation of Wrinkled Graphene
2015-01-01
The deformation of monolayer graphene, produced by chemical vapor deposition (CVD), on a polyester film substrate has been investigated through the use of Raman spectroscopy. It has been found that the microstructure of the CVD graphene consists of a hexagonal array of islands of flat monolayer graphene separated by wrinkled material. During deformation, it was found that the rate of shift of the Raman 2D band wavenumber per unit strain was less than 25% of that of flat flakes of mechanically exfoliated graphene, whereas the rate of band broadening per unit strain was about 75% of that of the exfoliated material. This unusual deformation behavior has been modeled in terms of mechanically isolated graphene islands separated by the graphene wrinkles, with the strain distribution in each graphene island determined using shear lag analysis. The effect of the size and position of the Raman laser beam spot has also been incorporated in the model. The predictions fit well with the behavior observed experimentally for the Raman band shifts and broadening of the wrinkled CVD graphene. The effect of wrinkles upon the efficiency of graphene to reinforce nanocomposites is also discussed. PMID:25765609
Interaction buckling - Progressive deformation
International Nuclear Information System (INIS)
Progressive deformation due to ratchetting may lead to the failure of structure in two different manners: by local fracture of the material when the strain is greater than an admissible limit or by a global destabilization of the loaded structure. This second mecanism will be considered here and corresponds to the principal interaction between buckling and progressive deformation. Under additional loading over a given dead load P, a structure initially in equilibrium will have an associated displacement u(t). Its failure by instability may occur if this displacement is great enough so that the response attains an instable branch of the load - displacement curve. Under cyclic additional loading of thermal or mechanical nature, this situation happens if there is ratchetting. The progressive plastic deformation which increases after each cycle, will produce greater and greater displacement and then perhaps failure by instability before local fracture by excessive local strain. In this paper, we present a theoretical and numerical analysis of this phenomena in function of the material characteristics and of the amplitude of the loads. (orig./RW)
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.
International Nuclear Information System (INIS)
By asymptotically matching a post-Newtonian (PN) metric to two perturbed Schwarzschild metrics, we generate approximate initial data (in the form of an approximate 4-metric) for a nonspinning black hole binary in a circular orbit. We carry out this matching through O(v4) in the binary's orbital velocity v, and thus the resulting data, like the O(v4) PN metric, are conformally curved. The matching procedure also fixes the quadrupole and octupole tidal deformations of the holes, including the 1PN corrections to the quadrupole fields. Far from the holes, we use the appropriate PN metric that accounts for retardation, which we construct using the highest-order PN expressions available to compute the binary's past history. The data set's uncontrolled remainders are thus O(v5) throughout the time slice; we also generate an extension to the data set that has uncontrolled remainders of O(v6) in the purely PN portion of the time slice (i.e., not too close to the holes). This extension also includes various other readily available higher-order terms. The addition of these terms decreases the constraint violations in certain regions, even though it does not increase the data's formal accuracy. The resulting data are smooth, since we join all the metrics together by smoothly interpolating between them. We perform this interpolation using transition functions constructed to avoid introducing excessive additional constraint violations. Bessive additional constraint violations. Because of their inclusion of tidal deformations and outgoing radiation, these data should substantially reduce both the high- and low-frequency components of the initial spurious ('junk') radiation observed in current simulations that use conformally flat initial data. Such reductions in the nonphysical components of the initial data will be necessary for simulations to achieve the accuracy required to supply Advanced LIGO and LISA with the templates necessary for parameter estimation.
Microstructural Analysis of Welding: Deformation and Strain
Quane, S. L.; Russell, K.
2003-12-01
Welding in pyroclastic deposits involves the sintering, compaction and flattening of hot glassy particles and is attended by systematic changes in physical properties. Welded materials contain implicit information regarding the total accumulated strain as well as the mechanisms of deformation. Here, we use detailed microstructural analysis of synthetic and natural welded materials to make quantitative estimates of strain and constrain the rheology of these materials during the welding process. Part one of our study comprises microstructural analysis of end products from unconfined high temperature deformation experiments on sintered cores of soda-lime silica glass spheres. This analogue material has relatively simple and well-characterized starting properties. Furthermore, the initially spherical shapes of particles provide excellent strain markers. Experiments were run at a variety of temperatures, strain rates and stresses resulting in end products with varying degrees of total strain. The nature of strain partitioning and accumulation are evaluated using image analysis techniques on scanned images and photomicrographs of thin sections cut perpendicular to the loading direction of each experimental product. Shapes of the individual deformed particles (e.g., oblate spheroids) were determined and the Scion image analysis program was used to create a best-fit ellipse for each particle. Statistics collected on each particle include: axial dimension (a), vertical dimension (c) and angle from the horizontal. The data are used to calculate the oblateness of each particle (1-c/a) and the angle of deformation induced foliation. Furthermore, the relative proportions of visible blue epoxy in the sample scans determine bulk porosity. The average oblateness of the particles is a direct, independent measure of the accumulated strain in each sample. Results indicate that these measured values are equal to calculated theoretical values of oblateness for spheroids undergoing the amount of constant-volume strain as determined by machine displacement. This information, combined with the near horizontal foliation angle for all samples strongly suggests that, in these experiments, all deformation is coaxial. Total strain in these experiments is accommodated by both longitudinal strain (calculated from porosity loss) and axial strain ("bulging" of the sample). A goal of ongoing analysis is to determine the role and proportion of each type of strain with increasing deformation. Furthermore, we are micro-analyzing products from experiments performed on natural pyroclastic materials for comparison with our dataset of results from similar analyses of naturally occurring samples.
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.
Rotary deformity in degenerative spondylolisthesis
Energy Technology Data Exchange (ETDEWEB)
Kang, Sung Gwon; Kim, Jeong; Kho, Hyen Sim; Yun, Sung Su; Oh, Jae Hee; Byen, Ju Nam; Kim, Young Chul [Chosun University College of Medicine, Gwangju (Korea, Republic of)
1994-05-15
We studied to determine whether the degenerative spondylolisthesis has rotary deformity in addition to forward displacement. We have made analysis of difference of rotary deformity between the 31 study groups of symptomatic degenerative spondylolisthesis and 31 control groups without any symptom, statistically. We also reviewed CT findings in 15 study groups. The mean rotary deformity in study groups was 6.1 degree(the standard deviation is 5.20), and the mean rotary deformity in control groups was 2.52 degree(the standard deviation is 2.16)(p < 0.01). The rotary deformity can be accompanied with degenerative spondylolisthesis. We may consider the rotary deformity as a cause of symptomatic degenerative spondylolisthesis in case that any other cause is not detected.
Rotary deformity in degenerative spondylolisthesis
International Nuclear Information System (INIS)
We studied to determine whether the degenerative spondylolisthesis has rotary deformity in addition to forward displacement. We have made analysis of difference of rotary deformity between the 31 study groups of symptomatic degenerative spondylolisthesis and 31 control groups without any symptom, statistically. We also reviewed CT findings in 15 study groups. The mean rotary deformity in study groups was 6.1 degree(the standard deviation is 5.20), and the mean rotary deformity in control groups was 2.52 degree(the standard deviation is 2.16)(p < 0.01). The rotary deformity can be accompanied with degenerative spondylolisthesis. We may consider the rotary deformity as a cause of symptomatic degenerative spondylolisthesis in case that any other cause is not detected
Lorentz deformation of the Bethe-Salpeter wave function
International Nuclear Information System (INIS)
Lorentz deformation properties of the covariant Bethe-Salpeter wave function are studied and compared with those of the covariant harmonic oscillator wave function. Space-time and momentum-energy diagrams are constructed and compared with those of the oscillator wave function. It is pointed out that the Lorentz deformation property of the Bethe-Salpeter wave function shown on these diagrams is strikingly similar to that of the oscillator wave function from which a physical interpretation can be derived for the time-separation variable between constituent quarks inside the hadron
Advanced deformation process modeling
Energy Technology Data Exchange (ETDEWEB)
Kocks, U.F.; Embury, J.D. [Los Alamos National Lab., NM (United States); Beaudoin, A.J. [Reynolds Metals (United States); Dawson, P.R. [Cornell Univ., Ithaca, NY (United States); MacEwen, S.R. [Alcan (Canada); Mecking, H.J. [Hamburg Technic (Germany)
1997-08-01
Progress was made in achieving a comprehensive and coherent description of material behavior in deformation processing. The materials included were metals, alloys, intermetallic compounds, arbitrary lattice structure, and metal matrix composites. Aspects of behavior modeled included kinetics of flow and strain hardening, as well as recrystallization and the various anisotropies of strength and compliance. Highlights include a new prediction of the limiting strength of materials at high temperature, a new understanding of the generation of new grain boundaries during forming operations, and a quantitatively verified computer simulation of texture development and the resulting behavioral anisotropies.
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.
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.
Quantizing Earth surface deformations
Bowin, C. O.; Yi, W.; Rosson, R. D.; Bolmer, T. S.; Sass, W. J.
2015-03-01
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.
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.
Radiologic evaluation of foot deformities
International Nuclear Information System (INIS)
In order to analyze foot deformities, the foot is divided into three compartments. Their normal and pathological positions are defined by the alignment of the bones' axes. The various foot deformities can be put down to a malalignment of the particular compartments. X-ray analysis of the malalignment allows a diagnosis to be made. The most important congenital and acquired foot deformities are discussed. (orig.)
Deformation processes in polycrystalline Zr by molecular dynamics simulations
Lu, Zizhe; Noordhoek, Mark J.; Chernatynskiy, Aleksandr; Sinnott, Susan B.; Phillpot, Simon R.
2015-07-01
Molecular dynamics simulation is used to characterize the deformation behavior of polycrystalline Zr. The predictions of two different potentials, an embedded atom method potential and a charge optimized many body potential are compared. The experimentally observed prismatic dislocations, pyramidal dislocations and twinning behaviors are produced in the simulations of [ 1 1 2 bar 0 ] and [0 0 0 1] textured structures and in fully 3D structure simulations. The relationship between the generalized stacking fault energy and the mechanical properties is discussed. In particular we find that the different shapes of the generalized stacking-fault energy curve for the two different interatomic descriptions of Zr have a significant effect on the deformation mechanisms. The deformation behavior of Zr is compared with analogous simulations of deformation of polycrystalline Mg.
Deformation-induced internal stresses in multiphase titanium aluminide alloys
International Nuclear Information System (INIS)
Long-range internal back stresses developed during room temperature tensile deformation of titanium aluminide alloys have been determined. Dip tests were implemented during the strain-controlled tensile deformation and the resulting sample deformation was monitored in the relaxation regime of the machine. The internal stress was determined as the critical stress at which the inelastic sample relaxation is reversed, i.e. going from the tensile direction to the compression direction. The investigation involves a wide range of alloy compositions with a corresponding variation in the strength properties. For the alloys investigated, the internal stress is about 80% of the yield stress. The mechanical tests were coupled with electron microscopy examination of the defect structure in order to assess the strain accommodation occurring during deformation. Possible sources for the built up internal stresses are discussed
Atomic-scale modeling of the deformation of nanocrystalline metals
Schiøtz, J; Jacobsen, K W
1998-01-01
Nanocrystalline metals, i.e. metals with grain sizes from 5 to 50 nm, display technologically interesting properties, such as dramatically increased hardness, increasing with decreasing grain size. Due to the small grain size, direct atomic-scale simulations of plastic deformation of these materials are possible, as such a polycrystalline system can be modeled with the computational resources available today. We present molecular dynamics simulations of nanocrystalline copper with grain sizes up to 13 nm. Two different deformation mechanisms are active, one is deformation through the motion of dislocations, the other is sliding in the grain boundaries. At the grain sizes studied here the latter dominates, leading to a softening as the grain size is reduced. This implies that there is an ``optimal'' grain size, where the hardness is maximal. Since the grain boundaries participate actively in the deformation, it is interesting to study the effects of introducing impurity atoms in the grain boundaries. We study ...
Guang-Wei, Fan; Fukuda, M; Ti-Fei, Han; Xue-Chao, Li; Zhong-Zhou, Ren; Wang, Xu
2013-01-01
Reaction- and interaction cross sections of 17C on a carbon target have been reanalyzed by use of the modified Glauber model. The analysis with a deformed Woods-Saxon density/potential suggests a big deformation structure for 17C. The existence of a tail in the density distribution supports its possibility of being a one-neutron halo structure. Under a deformed core plus single-particle assumption, analysis shows a dominant d-wave of the valence neutron in 17C. Key words Cross section, Glauber model, Density distribution, Halo, Deformation.
Shape Determination for Deformed Cavities
Energy Technology Data Exchange (ETDEWEB)
Lee, Lie-Quan; Akcelik, Volkan; Chen, Sheng; Ge, Lixin; Li, Zenghai; Ng, Cho; Xiao, Liling; Ko, Kwok; /SLAC; Ghattas, Omar; /Texas U.
2006-10-04
A realistic superconducting RF cavity has its shape deformed comparing to its designed shape due to the loose tolerance in the fabrication process and the frequency tuning for its accelerating mode. A PDE-constrained optimization problem is proposed to determine the deformation of the cavity. A reduce space method is used to solve the PDE-constrained optimization problem where design sensitivities were computed using a continuous adjoint approach. A proof-of-concept example is given in which the deformation parameters of a single cavity-cell with two different types of deformation were computed.
Computational investigation of plastic deformation in face-centered cubic materials
Semenov, Mikhail; Kolupaeva, Svetlana
2013-01-01
A mathematical model of plastic deformation in face-centered cubic (FCC) materials based on a balance model taking into account fundamental properties of deformation defects of a crystal lattice was developed. This model is based on a system of ordinary differential equations (ODE) accounting for various mechanisms of generation and annihilation of deformation defects for different external conditions. In-house developed software, SPFCC (Slip Plasticity of Face-Centered Cubi...
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.
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.)
Adsorption of n-Pentane on Mesoporous Silica and Adsorbent Deformation
Gor, G.Y.; Paris, O.; Prass, J.; P.A. Russo; Ribeiro Carrott, M.M.L.; Neimark, A.V.
2013-01-01
Development of quantitative theory of adsorption-induced deformation is important, e.g., for enhanced coalbed methane recovery by CO2 injection. It is also promising for the interpretation of experimental measurements of elastic properties of porous solids. We study deformation of mesoporous silica by n-pentane adsorption. The shape of experimental strain isotherms for this system differs from the shape predicted by thermodynamic theory of adsorption-induced deformation. We show that this dif...
The deformations of antibracket with even and odd deformation parameters
Konstein, S. E.; Tyutin, I. V.
2010-01-01
We consider antibracket superalgebras realized on the smooth Grassmann-valued functions with compact supports in n-dimensional space and with the grading inverse to Grassmanian parity. The deformations with even and odd deformation parameters of these superalgebras are presented for arbitrary n.
Micro-deformation and texture in engineering materials
Kiwanuka, Robert
This DPhil project is set in the context of single crystal elasticity-plasticity finite element modelling. Its core objective was to develop and implement a methodology for predicting the evolution of texture in single and dual-phase material systems. This core objective has been successfully achieved. Modelling texture evolution entails essentially modelling large deformations (as accurately as possible) and taking account of the deformation mechanisms that cause texture to change. The most important deformation mechanisms are slip and twinning. Slip has been modelled in this project and care has been taken to explore conditions where it is the dominant deformation mechanism for the materials studied. Modelling slip demands that one also models dislocations since slip is assumed to occur by the movement of dislocations. In this project a model for geometrically necessary dislocations has been developed and validated against experimental measurements.A texture homogenisation technique which relies on interpretation of EBSD data in order to allocate orientation frequencies based on representative area fractions has been developed. This has been coupled with a polycrystal plasticity RVE framework allowing for arbitrarily sized RVEs and corresponding allocation of crystallographic orientation. This has enabled input of experimentally measured initial textures into the CPFE model allowing for comparison of predictions against measured post-deformation textures, with good agreement obtained. The effect of texture on polycrystal physical properties has also been studied. It has been confirmed that texture indeed has a significant role in determining the average physical properties of a polycrystal.The thesis contributes to the following areas of micro-mechanics materials research: (i) 3D small deformation crystal plasticity finite element (CPFE) modelling, (ii) geometrically necessary dislocation modelling, (iii) 3D large deformation CPFE modelling, (iv) texture homogenisation methods, (v) single and dual phase texture evolution modelling, (vi) prediction of polycrystal physical properties, (vii) systematic calibration of the power law for slip based on experimental data, and (viii) texture analysis software development (pole figures and Kearns factors)..
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.
Fraktalnist deformational relief polycrystalline aluminum
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?.?. ??????????
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.
Static multipole deformations in nuclei
International Nuclear Information System (INIS)
The physics of static multipole deformations in nuclei is reviewed. Nuclear static moments result from the delicate balance between the vibronic Jahn-Teller interaction (particle-vibration coupling) and the residual interaction (pairing force). Examples of various permanent nuclear deformations are discussed
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)
Deformation of high-temperature superconductors
International Nuclear Information System (INIS)
Of the many families of high-temperature superconductors, only the properties of those discovered prior to 1989 - Y-Ba-Cu-O, Tl-Ba(Sr)-Ca-Cu-O, and Bi(Pb)-Sr-Ca-Cu-O - have been studied extensively. Deformation tests have been performed on YBa2Cu3Ox (Y-123), YBa2Cu4Ox (Y-124), TlBa2Ca2Cu3Ox (Bi-2223). The tests have revealed that plasticity is generally limited in these compounds and that the rate-controlling diffusional kinetics for creep are very slow. Nevertheless, hot forming has proved to be quite successful for fabrication of bulk high-temperature superconductors, so long as deformation rates are low or large hydrostatic stresses are applied. Steady-state creep data have proved to be useful in designing optimal heat treatments for superconductors and in support of more-fundamental diffusion experiments. The high-temperature superconductors are highly complex oxides, and it is a challenge to understand their deformation responses. In this paper, results of interest and operant creep mechanisms will be reviewed
Deformation induced martensite characterization in Fe-30%Ni-5%Cu alloy
Güler E.; Güler M.
2012-01-01
Deformation induced martensite properties were examined according to existing martensite morphology, crystallography and formation temperatures for different prior austenite homogenization conditions in Fe-30%Ni-5%Cu alloy. Scanning electron microscope (SEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques were employed to investigation. Scanning electron microscope observations showed elongated deformation induced martensite morphology in the austenite ph...
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.
Static and dynamic deformations of actinide nuclei
International Nuclear Information System (INIS)
The zero-point quadrupole-hexadecapole vibrations have been taken into account to calculate dynamical deformations for even-even actinide nuclei. The collective and intrinsic motions are separated according to the Born-Oppenheimer approximation. The collective Hamiltonian is constructed using the macroscopic-microscopic method in the potential energy part and the cranking model in the kinetic energy part. The BCS theory with a modified oscillator potential is applied to describe the intrinsic motion of nucleons. A new set of Nilsson potential parameters, which produces a much better description of the properties of light actinide nuclei, has also been found. (orig.)
Deformations of surface singularities
Szilárd, ágnes
2013-01-01
The present publication contains a special collection of research and review articles on deformations of surface singularities, that put together serve as an introductory survey of results and methods of the theory, as well as open problems, important examples and connections to other areas of mathematics. The aim is to collect material that will help mathematicians already working or wishing to work in this area to deepen their insight and eliminate the technical barriers in this learning process. This also is supported by review articles providing some global picture and an abundance of examples. Additionally, we introduce some material which emphasizes the newly found relationship with the theory of Stein fillings and symplectic geometry. This links two main theories of mathematics: low dimensional topology and algebraic geometry. The theory of normal surface singularities is a distinguished part of analytic or algebraic geometry with several important results, its own technical machinery, and several op...
Nuclear deformation at finite temperature
Alhassid, Y; Bertsch, G F
2014-01-01
Deformation, a key concept in our understanding of heavy nuclei, is based on a mean-field description that breaks the rotational invariance of the nuclear many-body Hamiltonian. We present a method to analyze nuclear deformations at finite temperature in a framework that preserves rotational invariance. The auxiliary-field Monte-Carlo method is used to generate the statistical ensemble and calculate the probability distribution associated with the quadrupole operator. Applying the technique to nuclei in the rare-earth region, we identify model-independent signatures of deformation and find that deformation effects persist to higher temperatures than the spherical-to-deformed shape phase-transition temperature of mean-field theory.
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.
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.
Deformations of the antibracket with Grassmann-valued deformation parameters
Konstein, S. E.; Tyutin, I. V.
2015-04-01
We consider the antibracket superalgebra realized on the space of smooth functions on ? 1 with values in the Grassmann algebra with one generator ? and consisting of elements of the form ?f 0 (x) + f 1 (x) with compactly supported f 0 . Any basis of the second cohomology space with coefficients in the adjoint representation of this superalgebra consists of three odd and infinitely many even elements. We describe a large class of deformations of this superalgebra with Grassmann-valued deformation parameters. In particular, we find all deformations of this superalgebra that have exactly three odd parameters.
Linkage between ? and ? vibrational excitations in deformed nuclei
International Nuclear Information System (INIS)
The consistent Q formalism of the interacting boson model (IBA) is systematically confronted with data on deformed vibrational states and found to be empirically supported. Exploiting this, we test a central IBA prediction, which is in stark contrast with traditional models, of an inherent linkage between the properties of the ? and ? vibrations, and find this linkage to be confirmed by the data
Electromagnetic method for definition of deformation martensite in stainless steels
International Nuclear Information System (INIS)
Mechanical and magnetic properties of tube specimens of OKh18N10T stainless steel depending on the degree of cold strain are studied. It is shown that the non-destructive eddy current testing can be applied for martensite determination in deformed samples
Deformation independent open brane metrics and generalized theta parameters
Berman, D S; Gran, U G; Larsson, H; Nielsen, M; Nilsson, B E W; Sundell, P; Berman, David S.; Cederwall, Martin; Gran, Ulf; Larsson, Henric; Nielsen, Mikkel; Nilsson, Bengt E. W.; Sundell, Per
2002-01-01
We investigate the consequences of generalizing certain well established properties of the open string metric to the conjectured open membrane and open Dp-brane metrics. By imposing deformation independence on these metrics their functional dependence on the background fields can be determined including the notorious conformal factor. In analogy with the non-commutativity parameter $\\Theta^{\\mu\
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.
Influence of soil conditioning on ground deformation during longitudinal tunneling
Jiang, Mingjing; Yin, Zhen-Yu
2014-03-01
Soil conditioning is often adopted to facilitate EPB shield tunneling. However, the resulting improvement of soil fluidity and the reduction of friction forces will also raise the ground deformation problem. This paper aims to investigate the influence of soil conditioning on the ground deformation during longitudinal tunneling. DEM is employed for this study due to its advantages in analyzing large deformations and discontinuous processes. Soil conditioning is modeled by reducing the interparticle friction of soils in a specific zone around the cutterhead of the tunnel. The tunnel advance with different soil-conditioning treatments is thus modeled. Comparisons are carried out on the ground deformation, i.e. ground surface settlement, vertical and horizontal displacements. The influence of soil conditioning on the ground deformation is clarified, and is associated with the fluidity from poor to favorite, and the mechanical properties from dilative to contractive are associated with the increase of soil conditioning. The results are helpful to determine the conditioned soils and control ground deformation for real constructions.
Rumin, T; Takigawa, N; Rumin, Tamanna; Hagino, Kouichi; Takigawa, Noboru
2000-01-01
We study fusion reactions of $^{16}$O with $^{154}$Sm, $^{186}$W and $^{238}$U at sub-barrier energies by a coupled-channels framework. We focus especially on the effects of $\\beta_{6}$ deformation and low-lying vibrational excitations of the target nucleus. It is shown that the inclusion of experimental data for all of these reactions. For the $^{154}$Sm and $^{238}$U targets, the octupole vibration significantly affects the fusion barrier distribution. The effect of $\\beta$ band is negligible in all the three reactions, while the $\\gamma$ band causes a non-negligible effect on the barrier distribution at energies above the main fusion barrier. We compare the optimum values of the deformation parameters obtained by fitting the fusion data with those obtained from inelastic scatterings and the ground state mass calculations. We show that the channel coupling of high multipolarity beyond the quadrupole coupling is dominated by the nuclear coupling and hence higher order Coulomb coupling does not much influence...
Deformation of phospholipid vesicles in an optical stretcher.
Delabre, Ulysse; Feld, Kasper; Crespo, Eleonore; Whyte, Graeme; Sykes, Cecile; Seifert, Udo; Guck, Jochen
2015-08-14
Phospholipid vesicles are common model systems for cell membranes. Important aspects of the membrane function relate to its mechanical properties. Here we have investigated the deformation behaviour of phospholipid vesicles in a dual-beam laser trap, also called an optical stretcher. This study explicitly makes use of the inherent heating present in such traps to investigate the dependence of vesicle deformation on temperature. By using lasers with different wavelengths, optically induced mechanical stresses and temperature increase can be tuned fairly independently with a single setup. The phase transition temperature of vesicles can be clearly identified by an increase in deformation. In the case of no heating effects, a minimal model for drop deformation in an optical stretcher and a more specific model for vesicle deformation that takes explicitly into account the angular dependence of the optical stress are presented to account for the experimental results. Elastic constants are extracted from the fitting procedures, which agree with literature data. This study demonstrates the utility of optical stretching, which is easily combined with microfluidic delivery, for the future serial, high-throughput study of the mechanical and thermodynamic properties of phospholipid vesicles. PMID:26135540
ASSESSMENT OF DEFORMATION AND STRENGTH OF SOILS STRENGTHENED BY CEMENTING
Directory of Open Access Journals (Sweden)
Sainov Mihail Petrovich
2014-09-01
Full Text Available Currently there are few studies of deformation and strength properties of loose soils strengthened by cementing. Based on the data of already arranged grout curtains it was determined that in cemented gravel-pebble soil there are 7...9 % of cement, which is less than in concrete. To assess deformation and strength of such soils it is possible to use the data of tests conducted by other authors, where the effect of cement contents on sand-cement mix properties was studied. Analysis of experimental data showed that cemented soil may be identified with concrete only with high content of cement (more than 10 %. At cement content 7...9 % in soil the strength deformation of cemented soil varies to a small extent. Its deformation becomes 2-3 times less. It greatly depends on compression stresses. The formulae are proposed which permit assessing the effect of compression and cement content on deformation of cemented soil. It is shown that strength of cemented soil is less than that even of the weakest concrete. It has a sufficiently high cohesion, but the friction angle is approximately the same as that of the initial soil.
Spacetimes for \\lambda-deformations
Sfetsos, Konstantinos
2014-01-01
We examine a recently proposed class of integrable deformations to two-dimensional conformal field theories. These {\\lambda}-deformations interpolate between a WZW model and the non-Abelian T-dual of a Principal Chiral Model on a group G or, between a G/H gauged WZW model and the non-Abelian T-dual of the geometric coset G/H. {\\lambda}-deformations have been conjectured to represent quantum group q-deformations for the case where the deformation parameter is a root of unity. In this work we show how such deformations can be given an embedding as full string backgrounds whose target spaces satisfy the equations of type-II supergravity. One illustrative example is a deformation of the Sl(2,R)/U(1) black-hole CFT. A further example interpolates between the $\\frac{SU(2)\\times SU(2)}{SU(2)}\\times\\frac{SL(2,R)\\times SL(2,R)}{SL(2,R)} \\times U(1)^4$ gauged WZW model and the non-Abelian T-dual of $AdS_3\\times S^3\\times T^4$ supported with Ramond flux.
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 c 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.
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.
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
Badique, Florent; Stamov, Dimitar R; Davidson, Patricia M; Veuillet, Matthieu; Reiter, Günter; Freund, Jean-Noël; Franz, Clemens M; Anselme, Karine
2013-04-01
We have recently demonstrated strong nuclear deformation of SaOs-2 osteosarcoma cells on poly-L-lactic acid (PLLA) micropillar substrates. In the present study, we first demonstrated that chemical and mechanical properties of the micropillar substrates have no dominant effect on deformation. However, SaOs-2 nucleus deformation could be strongly modulated by varying the pillar size and spacing, highlighting the importance of geometric constraints for shaping the nucleus. Furthermore, comparing the capacity for nuclear deformation in three different osteosarcoma cell lines (SaOs-2, MG-63 and OHS-4) revealed strong cell-type specific differences. Surprisingly, the highly-deformable SaOs-2 cell line displayed the highest cell stiffness as assessed by AFM-based colloidal force spectroscopy and featured a more prominent array of actin fibres above the nucleus, suggesting a link between actin-mediated cell stiffness and cell nucleus deformation. In contrast, in MG-63 and OHS-4 cells dense microtubule and vimentin networks seem to facilitate some nuclear deformation even in the absence of a prominent actin cytoskeleton. Together these results suggest that an interaction of all three cytoskeletal elements is needed for efficient nuclear deformation. In conclusion, the dominant parameters influencing nuclear deformation on micropillar substrates are not their material properties but the substrate geometry together with cell phenotype and cytoskeleton organization. PMID:23357373