Finite Amplitude Method for Charge-Changing Transitions in Axially-Deformed Nuclei
Mustonen, M T; Zenginerler, Z; Engel, J
2014-01-01
We describe and apply a version of the finite amplitude method for obtaining the charge-changing nuclear response in the quasiparticle random phase approximation. The method is suitable for calculating strength functions and beta-decay rates, both allowed and forbidden, in axially-deformed open-shell nuclei. We demonstrate the speed and versatility of the code through a preliminary examination of the effects of tensor terms in Skyrme functionals on beta decay in a set of spherical and deformed open-shell nuclei. Like the isoscalar pairing interaction, the tensor terms systematically increase allowed beta-decay rates. This finding generalizes previous work in semimagic nuclei and points to the need for a comprehensive study of time-odd terms in nuclear density functionals.
Khalaf A. M.
2015-04-01
Full Text Available The interacting boson model (sd-IBM1 with intrinsic coherent state is used to study the shape phase transitions from spherical U(5 to prolate deformed SU(3 shapes in Nd- Sm isotopic chains. The Hamiltonian is written in the creation and annihilation form with one and two body terms.For each nucleus a fitting procedure is adopted to get the best model parameters by fitting selected experimental energy levels, B(E2 transi- tion rates and two-neutron separation energies with the calculated ones.The U(5-SU(3 IBM potential energy surfaces (PES’s are analyzed and the critical phase transition points are identified in the space of model parameters.In Nd-Sm isotopic chains nuclei evolve from spherical to deformed shapes by increasing the boson number. The nuclei 150 Nd and 152 Sm have been found to be close to critical points.We have also studied the energy ratios and the B(E2 values for yrast band at the critical points.
Deforming Geometric Transitions
Rossi, Michele
2013-01-01
After a quick review of the wild structure of the complex moduli space of Calabi-Yau threefolds and the role of geometric transitions in this context (the Calabi-Yau web) the concept of "deformation equivalence" for geometric transitions is introduced to understand the arrows of the Gross-Reid Calabi-Yau web as deformation-equivalence classes of geometric transitions. Then the focus will be on some results and suitable examples to understand under which conditions it is possible to get "simpl...
On a selection rule for electric transitions in axially-symmetric nuclei
We consider many-body E-l transition matrix-elements between two nuclear states of different axially-symmetric deformations characterised by two different (mutually non-orthogonal) sets of single-particle wave-functions. Yet, when varying the deformations of the initial, final, or both these states one notices abrupt changes in the form of vanishing and possibly reappearance of the transition matrix elements calculated between the corresponding Slater determinants. The mechanism is explained in terms of the conservation of the |m| quantum number (absolute value of the projection of individual-nucleonic angular-momenta); consequences for the more general calculations of this type also without axial symmetry are discussed. (author)
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.
Computation of liquid drop deformation energy for axial symmetric nuclei
Computation methods for deformation dependent terms of the nuclear potential energy in the Myers-Swiatecki's and Krappe-Nix's variants of the liquid-drop model are presented. Also, an extension of the Krappe-Nix integral, surface and Coulomb energies formulas in case of reflection asymmetric deformations leading to fragments with different charge-to-mass ratio is introduced. (author)
Chaotic motion in axially symmetric potentials with oblate quadrupole deformation
By computing the Poincare's surfaces of section and Lyapunov exponents, we study the effect of introducing an oblate quadrupole in the dynamics associated with two generic spherical potentials of physical interest: the central monopole and the isotropic harmonic oscillator. In the former case we find saddle points in the effective potential, in contrast to the statements presented by Gueron and Letelier in [E. Gueron, P.S. Letelier, Phys. Rev. E 63 (2001) 035201]. The results we show in the second case have application in nuclear or atomic physics. In particular, we find values of oblate deformation leading to a disappearance of shell structure in the single-particle spectrum. -- Highlights: → We find chaotic motion around a monopole with oblate quadrupole deformation. → This corrects the statements introduced in [E. Gueron, P.S. Letelier, Phys. Rev. E 63 (2001) 035201]. → We present an alternative model for the potential due to an oblate deformed nuclei. → This leads to stochastic regions in the phase space of classical orbits. → It suggests that the shell structure of single-particle spectrum tends to disappear.
Chaotic motion in axially symmetric potentials with oblate quadrupole deformation
Letelier, Patricio S. [Departamento de Matematica Aplicada, IMECC, Universidade Estadual de Campinas, 13083-859, Campinas, SP (Brazil); Ramos-Caro, Javier, E-mail: javier@ime.unicamp.br [Departamento de Matematica Aplicada, IMECC, Universidade Estadual de Campinas, 13083-859, Campinas, SP (Brazil); Lopez-Suspes, Framsol, E-mail: framsol@gmail.com [Facultad de Telecomunicaciones, Universidad Santo Tomas and Escuela de Fisica, Universidad Industrial de Santander, Bucaramanga (Colombia)
2011-10-03
By computing the Poincare's surfaces of section and Lyapunov exponents, we study the effect of introducing an oblate quadrupole in the dynamics associated with two generic spherical potentials of physical interest: the central monopole and the isotropic harmonic oscillator. In the former case we find saddle points in the effective potential, in contrast to the statements presented by Gueron and Letelier in [E. Gueron, P.S. Letelier, Phys. Rev. E 63 (2001) 035201]. The results we show in the second case have application in nuclear or atomic physics. In particular, we find values of oblate deformation leading to a disappearance of shell structure in the single-particle spectrum. -- Highlights: → We find chaotic motion around a monopole with oblate quadrupole deformation. → This corrects the statements introduced in [E. Gueron, P.S. Letelier, Phys. Rev. E 63 (2001) 035201]. → We present an alternative model for the potential due to an oblate deformed nuclei. → This leads to stochastic regions in the phase space of classical orbits. → It suggests that the shell structure of single-particle spectrum tends to disappear.
A magnetic liquid deformable mirror for high stroke and low order axially symmetrical aberrations
Brousseau, D; Parent, J; Ruel, H J; Borra, Ermanno F.; Brousseau, Denis; Parent, Jocelyn; Ruel, Hubert-Jean
2006-01-01
We present a new class of magnetically shaped deformable liquid mirrors made of a magnetic liquid (ferrofluid). Deformable liquid mirrors offer advantages with respect to deformable solid mirrors: large deformations, low costs and the possibility of very large mirrors with added aberration control. They have some disadvantages (e.g. slower response time). We made and tested a deformable mirror, producing axially symmetrical wavefront aberrations by applying electric currents to 5 concentric coils made of copper wire wound on aluminum cylinders. Each of these coils generates a magnetic field which combines to deform the surface of a ferrofluid to the desired shape. We have carried out laboratory tests on a 5 cm diameter prototype mirror and demonstrated defocus as well as Seidel and Zernike spherical aberrations having amplitudes up to 20 microns, which was the limiting measurable amplitude of our equipment
SANCHO, Quasistatic Large Deformation Inelastic Response of Planar, Axial Solids
1 - Description of program or function: SANCHO is a finite element computer program designed to compute the quasistatic, large deformation, inelastic response of planar of axisymmetric solids. 2 - Method of solution: SANCHO uses finite strain constitutive theories for plasticity, volumetric plasticity, and metallic creep behavior. A constant bulk strain, bilinear displacement iso-parametric finite element is employed for the spatial discretization. The solution strategy used to generate the sequence of equilibrium solutions is a self-adaptive dynamic relaxation scheme which is based on explicit central difference pseudo-time integration and artificial damping. A master-slave algorithm for sliding interfaces is also implemented. 3 - Restrictions on the complexity of the problem: Large problems are easily accommodated and are limited only by the core storage available. With current dimensioning a maximum of twelve slide-lines is allowed
Wang, Y; Mao, N
2015-01-01
The influences of pre-tensions on the deformations of cylindrical shells made of various woven fabrics undergoing axial compression buckling process were studied. The fabric deformations were differentiated and quantified using the energy consumed to produce and recover them. Various types of deformation including elastic deformation, recoverable deformation and permanent deformation produced in the cyclic compression buckling-recovery processes were associated with their corresponding energy...
Skyrme random-phase-approximation description of lowest Kπ=2γ+ states in axially deformed nuclei
Nesterenko, V. O.; Kartavenko, V. G.; Kleinig, W.; Kvasil, J.; Repko, A.; Jolos, R. V.; Reinhard, P.-G.
2016-03-01
The lowest quadrupole γ -vibrational Kπ=2+ states in axially deformed rare-earth (Nd, Sm, Gd, Dy, Er, Yb, Hf, W) and actinide (U) nuclei are systematically investigated within the separable random-phase-approximation (SRPA) based on the Skyrme functional. The energies Eγ and reduced transition probabilities B (E 2 ) of 2γ+ states are calculated with the Skyrme forces SV-bas and SkM*. The energies of two-quasiparticle configurations forming the SRPA basis are corrected by using the pairing blocking effect. This results in a systematic downshift of Eγ by 0.3-0.5 MeV and thus in a better agreement with the experiment, especially in Sm, Gd, Dy, Hf, and W regions. For other isotopic chains, a noticeable overestimation of Eγ and too weak collectivity of 2γ+ states still persist. It is shown that domains of nuclei with low and high 2γ+ collectivity are related to the structure of the lowest two-quasiparticle states and conservation of the Nilsson selection rules. The description of 2γ+ states with SV-bas and SkM* is similar in light rare-earth nuclei but deviates in heavier nuclei. However SV-bas much better reproduces the quadrupole deformation and energy of the isoscalar giant quadrupole resonance. The accuracy of SRPA is justified by comparison with exact RPA. The calculations suggest that a further development of the self-consistent calculation schemes is needed for a systematic satisfactory description of the 2γ+ states.
Deformation twinning and the transition temperature of ferritic steels
The appearance of deformation twins in the wide temperature region of three structural ferritic steels was analyzed. It was found that the deformation twinning was associated with cleavage fracture. These results were verified in more detail on technically pure bcc Fe. For two grain sizes the tensile tests at two different strain rates and impact tests proved deformation twinning in the transition region of technically pure bcc Fe. In ductile specimens the deformation twinning was not observed. The fractographic analysis of cleaved specimens proved the reinitiation of cleavage on the twin boundary. Based on the experimental results, a linkage between the transition temperature and deformation twinning in ferritic steels can be assumed. (author)
Strength and Deformation of Axially Loaded Fiber-Reinforced Polymer Sheet Confined Concrete Columns
李静; 钱稼茹; 蒋剑彪
2004-01-01
Experimental results of 29 axially loaded fiber-reinforced polymer sheet (FS) confined concrete columns and two reference plain concrete columns are introduced. Twenty four column specimens were confined with carbon fiber sheet (CFS) and five column specimens were hybrid confined with both CFS and glass fiber sheet (GFS). The influence of aspect ratio, FS material, initial axial force ratio, and FS confinement degree on the strength and deformation of columns were studied. Based on the experimental results, the equations of complete stress-strain curve of CFS confined concrete are proposed. These equations are suitable for the nonlinear analysis of square and rectangular section columns. Suggestions of applying FS to confine concrete columns are presented.
Non-axial deformability of rotating atomic nuclei in the two-phase model
Basing on the generator-coordinate method a model is constructed representing a nucleus as a three-axis rotator having the coupled normal and superconducting phases. A variant of the model is calculated with phenomenological parameters for 156Er and 166Er. A considerable non-axial deformation appears in the 166Er transient nucleus for the states with angular momenta 0 < I < Isub(cr), where Isub(cr) is the value of the angular momentum at which the superconducting phase disappears. Effects resulting from difference in the nucleon momentum distributions in the two phases are considered
Watson's theorem and the $N\\Delta(1232)$ axial transition
Alvarez-Ruso, L; Nieves, J; Vacas, M J Vicente
2016-01-01
We present a new determination of the $N\\Delta$ axial form factors from neutrino induced pion production data. For this purpose, the model of Hernandez et al., Phys. Rev. D76, 033005 (2007) is improved by partially restoring unitarity. This is accomplished by imposing Watson's theorem on the dominant vector and axial multipoles. As a consequence, a larger $C_5^A(0)$, in good agreement with the prediction from the off-diagonal Goldberger-Treiman relation, is now obtained.
Yunqiang Liu; Jiuping Xu; Shize Wang; Bin Qi
2013-01-01
The axial stress and deformation of high temperature high pressure deviated gas wells are studied. A new model is multiple nonlinear equation systems by comprehensive consideration of axial load of tubular string, internal and external fluid pressure, normal pressure between the tubular and well wall, and friction and viscous friction of fluid flowing. The varied temperature and pressure fields were researched by the coupled differential equations concerning mass, momentum, and energy equatio...
Imole, O.I.; Kumar, N; Magnanimo, V.; S. Luding
2012-01-01
We compare element test experiments and simulations on the deformation of frictional, cohesive particles in a bi-axial box. We show that computer simulations with the Discrete Element Method qualitatively reproduce a uniaxial compression element test in the true bi-axial tester. We highlight the effects of friction and polydispersity on our simulations and present the second stress response namely the deviatoric stress as a function of the deviatoric strain.
Mott-superfluid transition of q-deformed bosons
The effect of q-deformation of the bosonic algebra on the Mott-superfluid transition for interacting lattice bosons described by the Bose–Hubbard model is studied using mean-filed theory. It has been shown that the Mott state proliferates and the initial periodicity of the Mott lobes as a function of the chemical potential disappears as the q-deformation increases. The ground state phase diagram as a function of the q-parameter exhibits superfluid order, which intervenes in narrow regions between Mott lobes, demonstrating the new concept of statistically induced quantum phase transition. - Highlights: • We study the effect of q-deformed bosons on superfluid transition. • A mean-field theory is employed. • Bosons can change statistics due to deformation of the commutation rules. • Statistically induced quantum phase transition is found
Mott-superfluid transition of q-deformed bosons
Kopeć, T.K., E-mail: kopec@int.pan.wroc.pl
2015-10-16
The effect of q-deformation of the bosonic algebra on the Mott-superfluid transition for interacting lattice bosons described by the Bose–Hubbard model is studied using mean-filed theory. It has been shown that the Mott state proliferates and the initial periodicity of the Mott lobes as a function of the chemical potential disappears as the q-deformation increases. The ground state phase diagram as a function of the q-parameter exhibits superfluid order, which intervenes in narrow regions between Mott lobes, demonstrating the new concept of statistically induced quantum phase transition. - Highlights: • We study the effect of q-deformed bosons on superfluid transition. • A mean-field theory is employed. • Bosons can change statistics due to deformation of the commutation rules. • Statistically induced quantum phase transition is found.
无
2001-01-01
The effect of the deformation condition on the axial compressive precision forming process of tube with curling die was investigated by using a rigid-plastic FEM. The results show that the forming accuracy depends mainly on geometric condition rρ/d0, little on tube material properties and friction condition; the relative gap Δ/2rρ of double-walled tubes obtained decreases with increasing rρ/d0, and there is a parameter k for a given t0/d0 or rρ/t0, when rρ,/d0＞k, Δ/2rρ＜1,otherwise Δ/2rρ＞1.
During normal operation, the collapsible CANDU® fuel sheath deforms, especially, it may deform into longitudinal ridges or collapse instantaneously into the axial gaps between the end pellet and endcap or between two neighbouring pellets. These phenomena occur under certain conditions, such as the coolant pressure exceeding critical pressures for longitudinal ridging or axial collapse. Both longitudinal ridging and axial collapse phenomena result from plastic instability in the sheath under coolant pressure. Longitudinal ridging features one or multiple lobes or 'ridges' (outward from the sheath surface) formed along the sheath in the longitudinal direction. Axial collapse features a 'valley' around the sheath circumference. Both phenomena can lead to sheath overstrain, which in turn potentially leads to sheath failure. The LONGER code, which contains empirical correlations, has been used to predict the critical pressures for these two sheath deformation phenomena. To study fuel behaviour outside of the application ranges of the LONGER empirical correlations, a mechanistic model is needed. FEAST (Finite Element Analysis for Stresses) is an AECL computer code used to assess the structural integrity of the CANDU fuel element. The FEAST code has recently been developed (to Version 3.1) to model processes occurring during longitudinal ridge formation and instantaneous collapse into the axial gap. The new models include those for geometric non-linearity (large deformation, large material rotation), non-linear stress-strain curve for plastic deformation, Zr-4 sheath creep law, and variable Young’s Modulus etc. This paper describes the mechanistic model (FEAST 3.1) development for analyses of longitudinal ridging and instantaneous collapse into axial gap, and the comparison with the results from empirical correlations in LONGER. (author)
Multi-axial load application and DIC measurement of advanced composite beam deformation behavior
Berggreen C.
2010-06-01
Full Text Available For the validation of a new beam element formulation, a wide set of experimental data consisting of deformation patterns obtained for a number of specially designed composite beam elements, have been obtained. The composite materials applied in the beams consist of glass-fiber reinforced plastic with specially designed layup configurations promoting advanced coupling behavior. Furthermore, the beams are designed with different cross-section shapes. The data obtained from the experiments are also used in order to improve the general understanding related to practical implementation of mechanisms of elastic couplings due to anisotropic properties of composite materials. The knowledge gained from these experiments is therefore essential in order to facilitate an implementation of passive control in future large wind turbine blades. A test setup based on a four-column MTS servo-hydraulic testing machine with a maximum capacity of 100 kN was developed, see Figure 1. The setup allows installing and testing beams of different cross-sections applying load cases such as axial extension, shear force bending, pure bending in two principal directions as well as pure torsion, see Figure 2. In order to apply multi-axial loading, a load application system consisting of three hydraulic actuators were mounted in two planes using multi-axial servo-hydraulic control. The actuator setup consists of the main actuator on the servo-hydraulic test machine working in the vertical axis (depicted on Figure 1 placed at the testing machine crosshead and used for application of vertical forces to the specimens. Two extra actuators are placed in a horizontal plane on the T-slot table of the test machine in different positions in order to apply loading at the tip of the specimen in various configurations. In order to precisely characterize the global as well as surface deformations of the beam specimens tested, a combination of different measurement systems were used during
Deformation Behavior and TExture Evolution of Steel Alloys under Axial-Torsional Loading
Siriruk, A.; Kant, M.; Penumadu, D.; Garlea, E.; Vogel, S.
2011-06-01
Using hollow cylinder samples with suitable geometry obtained from round bar stock, the deformation behavior of bcc Fe based 12L14 steel alloy is evaluated under multi-axial conditions. A stacked strain gage rosette and extensometer mounted on the cylindrical surface at the mid height of the specimen provided strain tensor as a function of applied stress for pure tensile and torsion tests prior to yielding. This study examines elastic and yield behavior and effects of these with respect to texture evolution. Hollow cylinder specimen geometry (tubes) with small wall thickness and relatively (to its thickness) large inner diameter is used. The variation of observed yield surface in deviatoric plane and the effect on mode of deformation (tension versus torsion versus its combination) on stress-strain behavior is discussed. Bulk texture was studied using neutron time-of-flight diffractometer at High-Pressure-Preferred Orientation (HIPPO) - Los Alamos Neutron Science Center (LANSCE) instrument and the evolution of texture and related anisotropy for pure tension versus torsion are also included.
Masafumi Noda
2011-01-01
Full Text Available Magnesium alloys can be used for reducing the weight of various structural products, because of their high specific strength. They have attracted considerable attention as materials with a reduced environmental load, since they help to save both resources and energy. In order to use Mg alloys for manufacturing vehicles, it is important to investigate the deformation mechanism and transition point for optimizing the material and vehicle design. In this study, we investigated the transition of the deformation mechanism during the high-temperature uniaxial tensile deformation of the AZ31 Mg alloy. At a test temperature of 523 K and an initial strain rate of 3×10−3 s-1, the AZ31 Mg alloy (mean grain size: ~5 μm exhibited stable deformation behavior and the deformation mechanism changed to one dominated by grain boundary sliding.
Nesterenko, V O; Kleinig, W; Jolos, R V; Kvasil, J; Reinhard, P -G
2015-01-01
The lowest quadrupole $\\gamma$-vibrational $K^{\\pi}=2^+$ states in axially deformed rare-earth (Nd, Sm, Gd, Dy, Er, Yb, Hf, W) and actinide (U) nuclei are systematically investigated within the fully self-consistent separable random-phase-approximation (SRPA) based on the Skyrme functional. The energies $E_{\\gamma}$ and reduced transition probabilities $B(E2)$ of $2^+_{\\gamma}$-states are calculated with the Skyrme forces SV-mas10 and SkM$^*$. We demonstrate that the blocking effect in pairing plays an important role. It leads to a systematic downshift of $E_{\\gamma}$ by 0.3-0.5 MeV and thus to a significant improvement of agreement with the experiment, especially in Sm, Gd, Dy, Hf, and W regions. For other isotopic chains, a noticeable overestimation of $E_{\\gamma}$ and too weak collectivity of $2^+_{\\gamma}$-states still persist. It is shown that domains of nuclei with a low and high $2^+_{\\gamma}$-collectivity are related with the structure of the lowest 2-quasiparticle states and maintenance of the Nilsso...
Sudhanshu Choudhary; S Qureshi
2012-10-01
We investigate electron transport properties in a deformed (8, 0) silicon carbide nanotube by applying self consistent non-equilibrium Green’s function formalism in combination with the density-functional theory to a two-probe molecular junction constructed from deformed nanotube. The results suggest significant reduction in threshold voltage in the case of both radially compressed and axially elongated (8, 0) SiCNTs, a large difference in current–voltage characteristics was observed. Analysis of frontier molecular orbitals (FMO) and transmission spectrum show bandgap reduction in deformed nanotubes. Deformation introduces electronic states near the Fermi level, enhancing the conduction properties of (8, 0) SiCNT. The FMOs and the orbitals corresponding to peaks in () around Fermi level obviously has some major contributions from the deformed site. However, localization of the electronic state near the Fermi level is weak in (8, 0) SiCNT, possibly because of its large bandgap.
Structure of collective modes in transitional and deformed nuclei
Caprio, M. A.
2005-01-01
The collective structure of atomic nuclei intermediate between spherical and quadrupole deformed structure presents challenges to theoretical understanding. However, models have recently been proposed in terms of potentials which are soft with respect to the quadrupole deformation variable beta. To test these models, information is needed on low-spin states of transitional nuclei. The present work involves measurement of electromagnetic decay properties of low-spin states for nuclei in the A=...
Eser, Jürgen; Rischke, Dirk H
2015-01-01
The transition in quantum chromodynamics (QCD) from hadronic matter to the quark-gluon plasma (QGP) at high temperatures and/or net-baryon densities is associated with the restoration of chiral symmetry and can be investigated in the laboratory via heavy-ion collisions. We study this chiral transition within the functional renormalization group (FRG) approach applied to the two-flavor version of the extended Linear Sigma Model (eLSM). The eLSM is an effective model for the strong interaction and features besides scalar and pseudoscalar degrees of freedom also vector and axial- vector mesons. We discuss the impact of the quark masses and the axial anomaly on the order of the chiral transition. We also confirm the degeneracy of the masses of chiral partners above the transition temperature. We find that the mass of the $a_1$ meson ($\\rho$ meson) decreases (increases) towards the chiral transition.
Eser, Jürgen; Grahl, Mara; Rischke, Dirk H.
2015-11-01
The transition in quantum chromodynamics from hadronic matter to the quark-gluon plasma at high temperatures and/or net-baryon densities is associated with the restoration of chiral symmetry and can be investigated in the laboratory via heavy-ion collisions. We study this chiral transition within the functional renormalization group approach applied to the two-flavor version of the extended linear sigma model (eLSM). The eLSM is an effective model for the strong interaction and features besides scalar and pseudoscalar degrees of freedom also vector and axial-vector mesons. We discuss the impact of the quark masses and the axial anomaly on the order of the chiral transition. We also confirm the degeneracy of the masses of chiral partners above the transition temperature. We find that the mass of the a1 meson (ρ meson) decreases (increases) towards the chiral transition.
The Deformation Behavior of TiNi Shape Memory Alloy under Axial Dynamic Compression
HUANG Xue-wen; DONG Guang-neng; ZHOU Zhong-rong; XIE You-bai
2004-01-01
The deformation behavior of Ti-50.9at%Ni shape memory alloy under axial compression dynamic loads was investigated by an MTS 858Mini Bionix test machine. The alloy were aged at 500℃ for an hour before being machined into specimens. The compression experiments were conducted at 20℃ and the variety of dynamic loads were controlled by the strain rate, which was 3mm/min, 15mm/min, 30mm/min and 50mm/min, respectively. The experimental results indicate that in the case of 3mm/min, stress-induced martensitic transformation occurs at about 350MPa when loading and reverse transformation at about 200MPa when unloading, during which the aged Ti-50.9at%Ni alloy shows the recoverable nonlinear pseudoelastic strain of 4.3% with the residual strain of 1.2% reserved. With the strain rate increasing, the area encloses by loading-curve and unloading-curve, i.e stress (strain) hysteresis becomes smaller and smaller and the residual strain also decreases, while critical stress for inducing martensitic transformation rises. At a higher strain rate the alloy exhibits linear-like pseudoelasticity, which is up to 4.5%.
C sub 6 sub 0 fullerene and its molecular complexes under axial and shear deformation
Spitsina, N G; Bashkin, I V; Meletov, K P
2002-01-01
We have studied the pristine C sub 6 sub 0 and its molecular complexes with the organic donors bis(ethylenedithio) tetrathiafulvalene (BEDT-TTF or ET) and tetramethyltetraselenafulvalene (TMTSF) by means of ESR and Raman spectroscopy at high pressure. The important changes in the ESR signal of C sub 6 sub 0 were observed under axial pressure combined with shear deformation. It is shown that the treatment at a anisotropic pressure of 4 GPa results in a reduction in the symmetry of the C sub 6 sub 0 molecule and the formation of radicals. Treatment of the molecular complex of (ET) sub 2 centre dot C sub 6 sub 0 at a pressure of approx 4.5 GPa and a temperature of 150 deg. C leads to the formation of C sub 6 sub 0 dimers. The Raman spectra of the molecular complex C sub 6 sub 0 centre dot TMTSF centre dot 2(CS sub 2) were measured in situ at ambient temperature and pressures up to 9.5 GPa. The pressure behaviour of the Raman peaks reveals singularity at 5.0 +- 0.5 GPa related to the softening and splitting of so...
Walker, G. J.; Solomon, W. J.
2007-01-01
Quantitative observations of transitional boundary layers in regions of strong flow deceleration on an axial compressor stator blade are reported. Measurements are obtained at a fixed chordwise position, and the blade incidence was varied by changing the compressor throughflow so as to move the transition region relative to the stationary probe. It was thus possible to observe typical boundary layer behavior at various stages of transition in the turbomachine environment. The range of observations covers separating laminar flow at transition onset, and reattachment of intermittently turbulent periodically separated shear layers.
Transitional DDES computations of the NREL Phase-VI rotor in axial flow conditions
Sørensen, Niels N.; Schreck, Scott
2014-01-01
In the present article we describe CFD simulations of the well known NREL Phase-VI rotor in axial flow conditions using a newly developed technique of combining turbulence modeling by the Delayed Detached Eddy Simulation (DDES) technique with laminar/turbulent transition modeling by a correlation...
Ring, P; Lalazissis, G A
1997-01-01
A Fortran program for the calculation of the ground state properties of axially deformed even-even nuclei in the relativistic framework is presented. In this relativistic mean field (RMF) approach a set of coupled differential equations namely the Dirac equation with potential terms for the nucleons and the Glein-Gordon type equations with sources for the meson and the electromagnetic fields are to be solved self-consistently. The well tested basis expansion method is used for this purpose. Accordingly a set of harmonic oscillator basis generated by an axially deformed potential are used in the expansion. The solution gives the nucleon spinors, the fields and level occupancies, which are used in the calculation of the ground state properties.
In this paper, the ratio of the mass coefficients for the γ-vibrational and rotational motion for the well deformed axially symmetric nuclei is calculated. Calculations are performed based on the cranking model approach. The results obtained show that the microscopic model based on the Woods–Saxon nuclear mean field potential and the pairing forces with a constant strength coefficient qualitatively explain the existing experimental data on the ratio of the mass coefficients. (author)
Correction of the axial and appendicular deformities in a patient with Silver-Russel syndrome
Ali Al Kaissi
2015-01-01
Full Text Available Background: Scoliosis and limb length discrepancy are the major orthopaedic abnormalities in patients with Silver-Russel syndrome (SRS. In this paper, we describe a series of orthopaedic interventions in an attempt to overcome the progressive pathologic mechanism in a 7-year-old girl who manifested the full phenotypic features of SRS. Materials and Methods: Unilateral hip dislocation, progressive scoliosis and limb length discrepancy have been dealt with through Pemberton osteotomy, spinal fusion and Taylor-Spatial-Frame respectively. Results: In order to correct the axial and the appendicular deformities a sum of seven operations were performed (between the age of 7 years and 13 years. Pemberton osteotomy was performed to treat dislocation of her right hip because of developmental dysplasia of the hip. Spinal fusion (spondylodesis of segments Th3-L5 was done to correct her scoliosis. And, to overcome the limb length discrepancy of 15-cm we used Taylor-Spatial-Frame with percutaneous distal corticotomy of the femur, and the proximal tibia, as well as the foot, were performed. We were able to minimize the limb length discrepancy to 5 cm. The girl became able to walk with the aid of a below knee orthosis and through lifting the left limb with 5-cm height shoe. Conclusion: Limb lengthening surgery in patients with multiple malformation complex as in SRS is associated with high recurrence risk because of; muscular hypotonia, overtubulation of the long bones, and the poor bone regenerative quality. Our interventions were principally directed towards improving the cosmetic outlook, functions and the biomechanics.
Influence of axial deformation of pipe string on down-hole operation%管柱轴向变形对井下作业的影响
李旭阳
2016-01-01
This paper reviews the impact of axial deformation of string on different down-hole operating conditions along with the importance of the calculation on axial deformation for the establishment of calculation model of down-hole string axial deformation theory.%综合分析了管柱轴向变形对井下不同作业工况的影响，阐述了计算井下作业管柱轴向变形的重要性，为建立井下作业管柱轴向变形理论计算模型做了很好的铺垫。
Guo, Huilong; Wang, Jiayi; Zhou, Chengbo;
2015-01-01
Deformation and yield induced structure transitions of polyamide 6 (PA6) were detected with the combination of the wide- and small-angle X-ray scattering (WAXS and SAXS) at 30 degrees C below glass transition temperature (T-g) of PA6. During deformation, gamma-alpha phase transition was found at ...
Contribution to the study of electromagnetic transitions in deformed nuclei
This work deals with the interaction between the nucleus and the electromagnetic field. We have adapted the Nilsson formalism to deformed uneven-uneven nuclei. We have studied the probability of gamma transitions and energy levels. In the first chapter we have recalled the improvements brought successively in nuclear models to describe electromagnetic transitions, we begin with the spherical shell model, then present the rotational model and end with the unified model. We have applied the unified model to deformed uneven-uneven nuclei in order to compute probability transitions and energy levels. We have set an experiment to compare computed values and experimental data. Our gamma spectrometry equipment is composed of NaI(Tl) crystals and EMI-1954 photomultipliers. We have tested our method by studying the gamma rays appearing during the decay reaction: 233Pa → 233U. We have measured the energy levels of 234Pa and the Nilsson formalism appears to give good results for low energy levels. We have also studied the decay reaction: 231Pa → 227Ac, we give detailed gamma spectra and a preliminary energy level scheme but the interpretation of the energy levels with the unified model is all the more complicated because of the high density of levels between 0 and 130 KeV
Hydrogen induced deformational effects in some transition metals
Investigation into regularities and nature of acceleration of creep, relaxation of stress ete under hydrogen absortion of (Fe, Pd, Nb, Ta, V) transition metals is carried out. It is shown, that under combined effect of internal or external fields of stress one can observe manifold acceleration of microplastic deformation of mechanical aftereffect (MAE). Mechanisms responsible for MAE initiated by hydrogen absorption are suggested on the ground of observation of elastic constants, internal friction and electrical conductivity and of data obtained by means of X-ray diffraction, metallographic and fractographic analyses
Concrete-Filled-Large Deformable FRP Tubular Columns under Axial Compressive Loading
Omar I. Abdelkarim; Mohamed A. ElGawady
2015-01-01
The behavior of concrete-filled fiber tubes (CFFT) polymers under axial compressive loading was investigated. Unlike the traditional fiber reinforced polymers (FRP) such as carbon, glass, aramid, etc., the FRP tubes in this study were designed using large rupture strains FRP which are made of recycled materials such as plastic bottles; hence, large rupture strain (LRS) FRP composites are environmentally friendly and can be used in the context of green construction. This study performed finite...
Mustonen, M T
2015-01-01
We use the finite amplitude method for computing charge-changing Skyrme-QRPA transition strengths in axially-deformed nuclei together with a modern Skyrme energy-density functional to fit several previously unconstrained parameters in the charge-changing time-odd part of the functional. With the modified functional we then calculate rates of beta-minus decay for all medium-mass and heavy even-even nuclei between the valley of stability and the neutron drip line. We fit the Skyrme parameters to a limited set of beta-decay rates, a set of Gamow-Teller resonance energies, and a set of spin-dipole resonance energies, in both spherical and deformed nuclei. Comparison to available experimental beta-decay rates shows agreement at roughly the same level as in other global QRPA calculations. We estimate the uncertainty in our rates all the way to the neutron drip line through a construction that extrapolates the errors of known beta-decay rates in nuclei with intermediate Q values to less stable isotopes with higher Q...
Concrete-Filled-Large Deformable FRP Tubular Columns under Axial Compressive Loading
Omar I. Abdelkarim
2015-10-01
Full Text Available The behavior of concrete-filled fiber tubes (CFFT polymers under axial compressive loading was investigated. Unlike the traditional fiber reinforced polymers (FRP such as carbon, glass, aramid, etc., the FRP tubes in this study were designed using large rupture strains FRP which are made of recycled materials such as plastic bottles; hence, large rupture strain (LRS FRP composites are environmentally friendly and can be used in the context of green construction. This study performed finite element (FE analysis using LS-DYNA software to conduct an extensive parametric study on CFFT. The effects of the FRP confinement ratio, the unconfined concrete compressive strength ( , column size, and column aspect ratio on the behavior of the CFFT under axial compressive loading were investigated during this study. A comparison between the behavior of the CFFTs with LRS-FRP and those with traditional FRP (carbon and glass with a high range of confinement ratios was conducted as well. A new hybrid FRP system combined with traditional and LRS-FRP is proposed. Generally, the CFFTs with LRS-FRP showed remarkable behavior under axial loading in strength and ultimate strain. Equations to estimate the concrete dilation parameter and dilation angle of the CFFTs with LRS-FRP tubes and hybrid FRP tubes are suggested.
Axial vector transition form factors of N \\rightarrow \\Delta in QCD
Kucukarslan, A; Ozpineci, A
2015-01-01
The isovector axial vector form factors of N \\rightarrow \\Delta transition are calculated by employing Light-cone QCD sum rules. The analytical results are analysed by both the conventional method, and also by a Monte Carlo based approach which allows one to scan all of the parameter space. The predictions are also compared with the results in the literature, where available. Although the Monte Carlo analysis predicts large uncertainties in the predicted results, the predictions obtained by the conventional analysis are in good agreement with other results in the literature.
Deformation transition of intact coal induced by gas injection
Wang Chunguang; Wang Changsheng; Wei Mingyao; Gong Bin; Tan Yuling
2014-01-01
Gas migration in coal bed is a multiple-physical process, of which not only includes gas desorption/diffusion through coal matrix and gas Darcy flow through the cleat system, but also results in deforma-tion of solid coal. Especially for enhanced coal bed methane (ECBM) and CO2 capture and sequestration (CCS), gas injection is mainly controlled by the gas diffusivity in the coal matrix and coal permeability. Although the relevant coal permeability models have been frequently developed, how the dual-porosity system of coal affects gas adsorption/diffusion is still poorly understood. In this paper, a series of experiments were carried out in order to investigate deformation evolution of intact coal subjected to hydrostatic pressure of different gases (including pure H2, N2 and CO2) under isotherm injection. In the testing process, the coal strain and injected gas pressure were measured simultaneously. The results show that the pressure of non-adsorptive helium remained unchanged throughout the isothermal injection process, in which the volumetric strain of the coal shrinked firstly and maintained unchanged at lower isobaric pressure. With the injected pressure increasing, the coal volume underwent a transition from shrinking to recovery (still less than initial volume of the coal). In contrast, N2 injection caused the coal to shrink firstly and then recover with decreasing gas pressure. The recovery volume was larger than the initial volume due to adsorption-induced swelling. For the case of CO2 injection, although the stronger adsorption effect could result in swelling of the solid coal, the presence of higher gas pressure appears to contribute the swelling coal to shrink. These results indicate that the evolution of coal defor-mation is time dependent throughout the migration of injected gas. From the mechanical characteristics of poroelastical materials, distribution of pore pressure within the coal is to vary with the gas injection, during which the pore pressure
Hot strength of Ti and Ti6Al4V deformed in axial compression
Plastic deformation of Ti and Ti6Al4V have been extensively studied in the literature. Sargent and Ashby, for instance, have assembled a deformation map for α and β-Ti using data available in the literature. Other authors have investigated the dependence of the stress at constant strain on the temperature and the strain rate. Few workers have published expressions which are useful to calculate mean flow stresses. however, none of the reported equations can be used to simulate full stress-strain curves. the purpose of this paper is to present equations suitable to describe stress-strain curves as a function of strain and Z, the Zener-Hollomon parameter for α and β Ti as well as for α + β Ti6Al4V
Large strain bulk deformation and brittle tough transitions in polyethylenes
Hillmansen, S
2001-01-01
Some tough, crystalline polymers can fail by fast brittle fracture. This thesis explores the role of ductile 'shear lips', which form at the fracture surface verges, in brittle-tough transitions. A new laboratory method was used to isolate this region, and to test its ability to draw rapidly, in polyethylenes. The test uses a conventional Charpy type specimen that is deeply notched and impact loaded in three-point bending by a single striker. The ligament, rapidly loaded in almost pure tension, first yields, and then necks down until failure. Initial results are encouraging and correlate well with the in-service performance. A fundamental study of large strain deformation, that avoids the complexity associated with impact tests, was then conducted with the aim of isolating the dominating influences that furnish a polymer with the ability to sustain rapid large strain deformation. True stress vs. true strain curves have been interpreted using the one dimensional spring dashpot model of Haward and Thackray (H-T...
Cook, M. J.; Sasagawa, G. S.; Zumberge, M. A.
2015-12-01
A geodetic pressure gauge, the Self-Calibrating Pressure Recorder (SCPR), was deployed on Axial Seamount on September 7, 2013. The device performs in situ pressure calibrations every 10 days by applying a time-invariant reference pressure from a piston gauge (also known as a deadweight calibrator) to continuously recording quartz pressure gauges through a hydraulic valve. The reference pressure measurements are then used to estimate and correct for the inherent drift in the quartz resonant seafloor pressure gauges. Pressure data are collected at 100 s integration intervals. A small subset of a year-long data set was recovered via an acoustic modem in August 2014. Using three epoch measurements, the pressure rate of change from September 2013 to August 2014 was -4.1 to -4.2 kPa/year, equivalent to uplift of 41- 42 cm/year. Other pressure time series and micro-bathymetric repeat surveys are in rough agreement with this SCPR rate. The instrument is scheduled for recovery in August 2015; the anticipated data collection interval spans the eruption on April 24, 2015. We present the drift-corrected pressure series and constraints estimated for magma supply rates during the inflation, eruption, and post-eruptive phases.
Comparison between formulas of rotational band for axially symmetric deformed nuclei
WU Xi; LEI Yi-An
2008-01-01
The experimental rotational spectra of the deformed nuclei available in even-even and odd-A nuclei in the rare-earth and actinide regions are systematically analyzed with several rotational spectra formulas,including Bohr-Mottelson's I(I+l)-expansion,Harris'w2-expansion,ab and abc formulas.It is shown that the simple 2-parameter ab formula is much better than the widely used 2-parameter Bohr-Mottelson's AB formula and Harris'αβ formula.The available data of the rotational spectra of both ground-state band in even-even nuclei and one-quaasiparticle band in odd-A nuclei can be conveniently and rather accurately reproduced by ab formula and abc formula.The moment of inertia and the variation with rotational frequency of angular momentum can be satisfactorily reproduced by ab and abc formulas.
Liu, Yunqiang; Xu, Jiuping; Wang, Shize; Qi, Bin
2013-01-01
The axial stress and deformation of high temperature high pressure deviated gas wells are studied. A new model is multiple nonlinear equation systems by comprehensive consideration of axial load of tubular string, internal and external fluid pressure, normal pressure between the tubular and well wall, and friction and viscous friction of fluid flowing. The varied temperature and pressure fields were researched by the coupled differential equations concerning mass, momentum, and energy equations instead of traditional methods. The axial load, the normal pressure, the friction, and four deformation lengths of tubular string are got ten by means of the dimensionless iterative interpolation algorithm. The basic data of the X Well, 1300 meters deep, are used for case history calculations. The results and some useful conclusions can provide technical reliability in the process of designing well testing in oil or gas wells. PMID:24163623
Yunqiang Liu
2013-01-01
Full Text Available The axial stress and deformation of high temperature high pressure deviated gas wells are studied. A new model is multiple nonlinear equation systems by comprehensive consideration of axial load of tubular string, internal and external fluid pressure, normal pressure between the tubular and well wall, and friction and viscous friction of fluid flowing. The varied temperature and pressure fields were researched by the coupled differential equations concerning mass, momentum, and energy equations instead of traditional methods. The axial load, the normal pressure, the friction, and four deformation lengths of tubular string are got ten by means of the dimensionless iterative interpolation algorithm. The basic data of the X Well, 1300 meters deep, are used for case history calculations. The results and some useful conclusions can provide technical reliability in the process of designing well testing in oil or gas wells.
Chabab, M; Lahbas, A; Oulne, M
2016-01-01
In this paper, we present a theoretical study of a conjonction of $\\gamma$-rigid and $\\gamma$-stable collective motions in critical point symmetries of the phase transitions from spherical to deformed shapes of nuclei using exactly separable version of the Bohr Hamiltonian with deformation-dependent mass term. The deformation-dependent mass is applied simultaneously to $\\gamma$-rigid and $\\gamma$-stable parts of this famous collective Hamiltonian. Moreover, the $\\beta$ part of the problem is described by means of Davidson potential, while the $\\gamma$-angular part corresponding to axially symmetric shapes is treated by a Harmonic Osillator potential. The energy eigenvalues and normalized eigenfunctions of the problem are obtained in compact forms by making use of the asymptotic iteration method. The combined effect of the deformation-dependent mass and rigidity as well as harmonic oscillator stiffness parameters on the energy spectrum and wave functions is duly investigated. Also, the electric quadrupole tran...
The influence of biquadratic exchange on the Heisenberg model with strong axial anisotropy is examined for the case of spins on a body-centered tetragonal lattice with competing bilinear exchange interactions along the c axis. Contrary to the usual axial next-nearest-neighbor Ising model with third-neighbor exchange also included, a low-temperature spin-wave calculation reveals that biquadratic exchange can stabilize the sequence of phases period 3→period 2. Mean-field analysis, with support from Monte Carlo simulations, suggests a higher-temperature transition to an incommensurate state. This sequence of phase transitions has recently been observed in UNi2Si2. The importance of fluctuations is emphasized
Chandra, R; Rath, P K; Raina, P K; Hirsch, J G
2009-01-01
The two neutrino and neutrinoless double beta decay of $^{94,96}$Zr, $^{98,100}$Mo, $^{104}$Ru, $^{110}$Pd, $^{128,130}$Te and $^{150}$Nd isotopes for the $0^{+}\\to 0^{+}$ transition is studied within the PHFB framework along with an effective two-body interaction consisting of pairing, quadrupole-quadrupole and hexadecapole-hexadecapole correlations. It is found that the effect of hexadecapolar correlations can be assimilated substantially as a renormalization of the quadrupole-quadrupole interaction. The effect of deformation on nuclear transition matrix elements is investigated by varying the strength of quadrupolar correlations in the parent and daughter nuclei independently. The variation of the nuclear transition matrix elements as a function of the difference in deformation parameters of parent and daughter nuclei reveals that in general, the former tend to be maximum for equal deformation and they decrease as the difference in deformation parameters increases, exhibiting a very similar trend for the $...
Yamada, Taishi; Takamuku, Shota; Matsui, Hiroshi; Champagne, Benoît; Nakano, Masayoshi
2014-07-01
We investigate the axial ligand effects on the diradical character (y) dependences of the second hyperpolarizabilities (γ) of transition-metal dinuclear complexes, Mo(I)2(CO)2, with different bond lengths (R) using the spin-unrestricted coupled-cluster method. Mo(I)2(CO)2 exhibits intrinsic y-γ correlation and dominant dσ-electron contribution to the maximum γ (γmax), which are also observed in the bare dinuclear analogs. The axial-ligand coordination to Mo(I)2 is found to cause the increase of the diradical character of the dσ orbital, the emergence of large negative γ for small R, and an enhancement of |γmax| by a factor of ∼30 as compared to the bare analogs.
A polycrystal finite element (FE) model describing the temperature evolution of low carbon steel is proposed in order to forecast the local mechanical fields as a function of temperature, for bainitic microstructure submitted to tri-axial loading. The model is designed for finite strains, large lattice rotations and temperatures ranging into the brittle-ductile transition domain. The dislocation densities are the internal variables. At low temperature in Body Centred Cubic (BCC) materials, plasticity is governed by double kink nucleation of screw dislocations, whereas at high temperature, plasticity depends on interactions between mobile dislocations and the forest dislocations. In this paper, the constitutive law and the evolution of the dislocation densities are written as a function of temperature and describe low and high temperature mechanisms. The studied aggregates are built from Electron Back Scattering Diffraction (EBSD) images of real bainitic steel. The aggregate is submitted to a tri-axial loading in order to describe the material at a crack tip. Mechanical parameters are deduced from mechanical tests. The local strain and stress fields, computed for different applied loadings, present local variations which depend on temperature and on tri-axial ratio. The distribution curves of the maximal principal stresses show that heterogeneities respectively increase with temperature and decrease with tri-axial ratio. A direct application of this model provides the evaluation of the rupture probability within the aggregate, which is treated as the elementary volume in the weak link theory. A comparison with the Beremin criterion calibrated on experimental data, shows that the computed fracture probability dispersion induced by the stress heterogeneities is of the same order than the measured dispersion. Temperature and stress tri-axiality ratio effects are also investigated. It is shown that these two parameters have a strong effect on fracture owing to their
Ouyang, Bin; Lan, Guoqiang; Guo, Yinsheng; Mi, Zetian; Song, Jun
2015-11-01
First-principles calculations were performed to investigate the phase stability and transition within four monolayer transition-metal dichalcogenide (TMD) systems, i.e., MX2 (M = Mo or W and X = S or Se) under coupled electron doping and lattice deformation. With the lattice distortion and electron doping density treated as state variables, the energy surfaces of different phases were computed, and the diagrams of energetically preferred phases were constructed. These diagrams assess the competition between different phases and predict conditions of phase transitions for the TMDs considered. The interplay between lattice deformation and electron doping was identified as originating from the deformation induced band shifting and band bending. Based on our findings, a potential design strategy combining an efficient electrolytic gating and a lattice straining to achieve controllable phase engineering in TMD monolayers was demonstrated.
Ouyang, Bin; Lan, Guoqiang; Song, Jun, E-mail: jun.song2@mcgill.ca [Department of Mining and Materials Engineering, McGill University, Montreal, Quebec H3A 0C5 (Canada); Guo, Yinsheng [Department of Chemistry, Columbia University, New York, New York 10027 (United States); Mi, Zetian [Department of Electrical and Computer Engineering, McGill University, Montreal, Quebec H3A 0E9 (Canada)
2015-11-09
First-principles calculations were performed to investigate the phase stability and transition within four monolayer transition-metal dichalcogenide (TMD) systems, i.e., MX{sub 2} (M = Mo or W and X = S or Se) under coupled electron doping and lattice deformation. With the lattice distortion and electron doping density treated as state variables, the energy surfaces of different phases were computed, and the diagrams of energetically preferred phases were constructed. These diagrams assess the competition between different phases and predict conditions of phase transitions for the TMDs considered. The interplay between lattice deformation and electron doping was identified as originating from the deformation induced band shifting and band bending. Based on our findings, a potential design strategy combining an efficient electrolytic gating and a lattice straining to achieve controllable phase engineering in TMD monolayers was demonstrated.
Commensurate-incommensurate phase transition in the deformed crystal
Using simple orthorhombic microscopic model the commensurate-incommensurate phase transition has been studied. Coupling of the order parameter with spontaneous strain may lead to process which uses the ferroelastic domain walls to introduce the discommensurations to the incommensurate phase. (author). 4 refs, 1 fig
Liquid-solid phase transitions in a deformable container
Krejčí, Pavel; Rocca, E.; Sprekels, J.
1. Berlin: Springer, 2010 - (Albers, B.), s. 285-300 ISBN 978-3-642-11444-1 Institutional research plan: CEZ:AV0Z10190503 Keywords : phase transition * energy balance * equilibrium state Subject RIV: BA - General Mathematics http://link.springer.com/chapter/10.1007%2F978-3-642-11445-8_22
Stoitsov, M. V.; Dobaczewski, J.; Nazarewicz, W.; Ring, P.
2005-04-01
We describe the program HFBTHO for axially deformed configurational Hartree-Fock-Bogolyubov calculations with Skyrme-forces and zero-range pairing interaction using Harmonic-Oscillator and/or Transformed Harmonic-Oscillator states. The particle-number symmetry is approximately restored using the Lipkin-Nogami prescription, followed by an exact particle number projection after the variation. The program can be used in a variety of applications, including systematic studies of wide ranges of nuclei, both spherical and axially deformed, extending all the way out to nucleon drip lines. Program summaryTitle of the program: HFBTHO (v1.66p) Catalogue number: ADUI Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADUI Licensing provisions: none Computers on which the program has been tested: Pentium-III, Pentium-IV, AMD-Athlon, IBM Power 3, IBM Power 4, Intel Xeon Operating systems: LINUX, Windows Programming language used: FORTRAN-95 Memory required to execute with typical data: 59 MB when using N=20 No. of bits in a word: 64 No. of processors used: 1 Has the code been vectorized?: No No. of bytes in distributed program, including test data, etc.: 195 285 No. of lines in distributed program: 12 058 Distribution format: tar.gz Nature of physical problem: The solution of self-consistent mean-field equations for weakly bound paired nuclei requires a correct description of the asymptotic properties of nuclear quasiparticle wave functions. In the present implementation, this is achieved by using the single-particle wave functions of the Transformed Harmonic Oscillator, which allows for an accurate description of deformation effects and pairing correlations in nuclei arbitrarily close to the particle drip lines. Method of solution: The program uses the axially Transformed Harmonic Oscillator (THO) single-particle basis to expand quasiparticle wave functions. It iteratively diagonalizes
Systematics of Absolute Gamma Ray Transition Probabilities in Deformed Odd-A Nuclei
Malmskog, S.G.
1965-11-15
All known experimentally determined absolute gamma ray transition probabilities between different intrinsic states of deformed odd-A nuclei in the rare earth, region (153 < A < 181) and in the actinide region (A {>=} 227) are compared with transition probabilities (Weisskopf and Nilsson estimate). Systematic deviations from the theoretical values are found. Possible explanations for these deviations are given. This discussion includes Coriolis coupling, {delta}K ={+-}2 band-mixing effects and pairing interaction.
Systematics of Absolute Gamma Ray Transition Probabilities in Deformed Odd-A Nuclei
All known experimentally determined absolute gamma ray transition probabilities between different intrinsic states of deformed odd-A nuclei in the rare earth, region (153 < A < 181) and in the actinide region (A ≥ 227) are compared with transition probabilities (Weisskopf and Nilsson estimate). Systematic deviations from the theoretical values are found. Possible explanations for these deviations are given. This discussion includes Coriolis coupling, ΔK =±2 band-mixing effects and pairing interaction
Defect structures and phase transitions of FeRh alloys deformed at high speed deformation
Oshima, Ryuichiro; Hori, Fuminobu; Kibata, Yasunori; Komatsu, Masao; Kiritani, Michio
2003-06-15
Fe-Rh alloys of Rh concentrations ranging from 40 to 50at.% and of B2 phase were deformed by use of a compression machine capable of running tests at high speeds of impact. Induced complicated substructures and phases were examined by X-ray diffraction (XRD), transmission electron microscopy (TEM), and positron annihilation spectroscopy (PAS). A characteristic arrangement of L1{sub 0} domains was observed, along with very small transformed A1 domains and dispersed in the residual B2 matrix. On the basis of the experimental results, we suggest a coupling of a pair of shears along {l_brace}112{r_brace}<11-1>{sub B2} for the transformation mechanisms from B2 to L1{sub 0} and A1 phases.
Xie, Hua; Liu, Zhiling; Zhao, Zhi; Kong, Xiangtao; Fan, Hongjun; Tang, Zichao; Jiang, Ling
2016-06-01
A series of yttrium oxide-carbonyls are prepared via a laser vaporization supersonic cluster source in the gas phase and identified by mass-selected infrared photodissociation (IRPD) spectroscopy in the C-O stretching region and by comparing the observed IR spectra with those from quantum chemical calculations. For YO(CO)4(+), all four CO ligands prefer to occupy the equatorial site of the YO(+) unit, leading to a quadrangular pyramid with C4v symmetry. Two energetically nearly degenerate isomers are responsible for YO(CO)5(+), in which the fifth CO ligand is either inserted into the equatorial plane of YO(CO)4(+) or coordinated opposite the oxygen on the C4 axis. YO(CO)6(+) has a pentagonal bipyramidal structure with C5v symmetry, which includes five equatorial CO ligands and one axial CO ligand. The present IRPD spectroscopic and theoretical study of YO(CO)n(+) extends the first shell coordination number of CO ligands in metal monoxide carbonyls to six. The transition from equatorial to axial CO chemisorption in these yttrium oxide-carbonyls is fortunately observed at n = 5, providing new insight into ligand interactions and coordination for the transition metal oxides. PMID:27158889
The off-shell axial anomaly via the γ*π0 → γ transition
The γ*π0 → γ form factor, including the extension off the pion mass-shell, is obtained from a generalized impulse approximation within a QCD-based model field theory known to provide an excellent description of the pion charge form factor. This approach implements dressing of the vertex functions and propagators consistent with dynamical chiral symmetry breaking, gauge invariance, quark confinement and perturbative QCD. Soft nonperturbative behavior, dictated by the axial anomaly, is found to evolve to the perturbative QCD limit only for Q2 ≥ 20 GeV2
Paraska, Peter J.
1993-01-01
This report documents an analytical study of the response of unsymmetrically laminated cylinders subjected to thermally-induced preloading effects and compressive axial load. Closed-form solutions are obtained for the displacements and intralaminar stresses and recursive relations for the interlaminar shear stress were obtained using the closed-form intralaminar stress solutions. For the cylinder geometries and stacking sequence examples analyzed, several important and as yet undocumented effects of including thermally-induced preloading in the analysis are observed. It should be noted that this work is easily extended to include uniform internal and/or external pressure loadings and the application of strain and stress failure theories.
Jones, K E; Pierce, S E
2016-03-01
Ecological diversification into new environments presents new mechanical challenges for locomotion. An extreme example of this is the transition from a terrestrial to an aquatic lifestyle. Here, we examine the implications of life in a neutrally buoyant environment on adaptations of the axial skeleton to evolutionary increases in body size. On land, mammals must use their thoracolumbar vertebral column for body support against gravity and thus exhibit increasing stabilization of the trunk as body size increases. Conversely, in water, the role of the axial skeleton in body support is reduced, and, in aquatic mammals, the vertebral column functions primarily in locomotion. Therefore, we hypothesize that the allometric stabilization associated with increasing body size in terrestrial mammals will be minimized in secondarily aquatic mammals. We test this by comparing the scaling exponent (slope) of vertebral measures from 57 terrestrial species (23 felids, 34 bovids) to 23 semi-aquatic species (pinnipeds), using phylogenetically corrected regressions. Terrestrial taxa meet predictions of allometric stabilization, with posterior vertebral column (lumbar region) shortening, increased vertebral height compared to width, and shorter, more disc-shaped centra. In contrast, pinniped vertebral proportions (e.g. length, width, height) scale with isometry, and in some cases, centra even become more spool-shaped with increasing size, suggesting increased flexibility. Our results demonstrate that evolution of a secondarily aquatic lifestyle has modified the mechanical constraints associated with evolutionary increases in body size, relative to terrestrial taxa. PMID:26679743
The model, introduced in a previous paper, for the description of the octupole and quadrupole degrees of freedom in conditions close to the axial symmetry is used to describe the negative-parity band based on the first octupole vibrational state in nuclei close to the critical point of the U(5)-to-SU(3) phase transition. The situation of 150Nd and 152Sm is discussed in detail. The positive-parity levels of these nuclei, and also the in-band E2 transitions, are reasonably accounted for by the X(5) model. With simple assumptions on the nature of the octupole vibrations, it is also possible to describe the negative-parity sector with comparable accuracy without changing the description of the positive-parity part.
The deformation units in metallic glasses revealed by stress-induced localized glass transition
Huo, L. S.; Ma, J.; Ke, H. B.; Bai, H. Y.; Zhao, D. Q.; Wang, W. H.
2012-06-01
We report that even in quasi-static cyclic compressions in the apparent elastic regimes of the bulk metallic glasses, the precisely measured stress-strain curve presents a mechanical hysteresis loop, which is commonly perceived to occur only in high-frequency dynamic tests. A phenomenological viscoelastic model is established to explain the hysteresis loop and demonstrate the evolutions of the viscous zones in metallic glasses during the cyclic compression. The declining of the viscosity of the viscous zones to at least 1 × 1012 Pa s when stress applied indicates that stress-induced localized glass to supercooled liquid transition occurs. We show that the deformation units of metallic glasses are evolved from the intrinsic heterogeneous defects in metallic glasses under stress and the evolution is a manifestation of the stress-induced localized glass transition. Our study might provide a new insight into the atomic-scale mechanisms of plastic deformation of metallic glasses.
Search for linking transitions between the superdeformed and normal deformed states in 152Dy
The Eurogam I γ-ray array has been used to search for the linking transitions between the superdeformed (SD) and normal deformed states in 152Dy. Triple γ-ray coincidence data were analysed by employing the technique of summation of discrete γ-rays observed in coincidence with the transitions in the lowest energy (yrast) SD band in 152Dy. Several high energy peaks have been observed in the spectrum of the summed γ-rays and these are consistent with decay paths between the two structures. Analysis of these data and of single γ-ray spectra confirm that the decay is highly fragmented and that decays occur through a quasi-continuum of states between the SD and normal deformed minima. (author). Letter-to-the-editor
Search for linking transitions between the superdeformed and normal deformed states in {sup 152}Dy
Bentley, M.A.; Beausang, C.W.; Twin, P.J.; Dagnall, P.J.; Atac, A.; Beck, F.A.; Byrski, T.; Clarke, S.; Curien, D.M.; Duchene, G.; France, G. de; Forsyth, P.D.; Herskind, B.; Haas, B.; Lisle, J.C.; Nyako, B.M.; Nyberg, J.; Paul, E.S.; Simpson, J.; Styczen, J.; Vivien, J.P.; Zuber, K. [Sch. of Sci., Staffordshire Univ., Stoke-on-Trent (United Kingdom)
1995-04-01
The Eurogam I {gamma}-ray array has been used to search for the linking transitions between the superdeformed (SD) and normal deformed states in {sup 152}Dy. Triple {gamma}-ray coincidence data were analysed by employing the technique of summation of discrete {gamma}-rays observed in coincidence with the transitions in the lowest energy (yrast) SD band in {sup 152}Dy. Several high energy peaks have been observed in the spectrum of the summed {gamma}-rays and these are consistent with decay paths between the two structures. Analysis of these data and of single {gamma}-ray spectra confirm that the decay is highly fragmented and that decays occur through a quasi-continuum of states between the SD and normal deformed minima. (author). Letter-to-the-editor.
This paper deals with investigation of characteristics properties of thermopower, resistance and Shubnikov de Haas oscillations at electronic topological transition induced by anisotropic deformation in Bi1-xSbx thin wires (authors)
Combined fast reversible liquidlike elastic deformation with topological phase transition in Na3Bi
Cheng, Xiyue; Li, Ronghan; Li, Dianzhong; Li, Yiyi; Chen, Xing-Qiu
2015-10-01
By means of first-principles calculations, we identified the structural phase transition of Na3Bi from the hexagonal ground state to the cubic c F 16 phase above 0.8 GPa, in agreement with the experimental findings. Upon the releasing of pressure, the cF 16 phase of Na3Bi is mechanically stable at ambient condition. The calculations revealed that the c F 16 phase is topological semimetal (TS), similar to well-known HgTe, and it even exhibits an unusually low C' modulus (only about 1.9 GPa) and a huge anisotropy Au of as high as 11, which is the third-highest value among all known cubic crystals in their elastic behaviors. These facts render cF 16 -type Na3Bi very soft with a liquidlike elastic deformation in the (110) slip system. Importantly, accompanying this deformation, Na3Bi shows a topological phase transition from a TS state at its strain-free cubic phase to a topological insulator (TI) at its distorted phase. Because the C' elastic deformation has almost no energy cost in a reversible and liquidlike soft manner, cF 16 -type Na3Bi would potentially provide a fast on/off switching method between TS and TI, which would be beneficial to quantum electronic devices for practical applications.
Böhm, Harald; Stief, Felix; Sander, Klaus; Hösl, Matthias; Döderlein, Leonhard
2015-09-01
Malaligned knees are predisposed to the development and progression of unicompartmental degenerations because of the excessive load placed on one side of the knee. Therefore, guided growth in skeletally immature patients is recommended. Indication for correction of varus/valgus deformities are based on static weight bearing radiographs. However, the dynamic knee abduction moment during walking showed only a weak correlation to malalignment determined by static radiographs. Therefore, the aim of the study was to measure the effects of guided growth on the normalization of frontal plane knee joint moments during walking. 15 legs of 8 patients (11-15 years) with idiopathic axial varus or valgus malalignment were analyzed. 16 typically developed peers served as controls. Instrumented gait analysis and clinical assessment were performed the day before implantation and explantation of eight-plates. Correlation between static mechanical tibiofemoral axis angle (MAA) and dynamic frontal plane knee joint moments and their change by guided growth were performed. The changes in dynamic knee moment in the frontal plane following guided growth showed high and significant correlation to the changes in static MAA (R=0.97, p<0.001). Contrary to the correlation of the changes, there was no correlation between static and dynamic measures in both sessions. In consequence two patients that had a natural knee moment before treatment showed a more pathological one after treatment. In conclusion, the changes in the dynamic load situation during walking can be predicted from the changes in static alignment. If pre-surgical gait analysis reveals a natural load situation, despite a static varus or valgus deformity, the intervention must be critically discussed. PMID:26159802
M1 transitions in even-even deformed nuclei and the IBA
It is shown that the Interacting Boson Approximation can produce essentially identical results for M1 transitions in deformed even-even nuclei as can be obtained from the geometrical approach, and many comparisons with experiment are already available for the latter in the literature. Since no physical constants are involved in the IBA-1 formalism, it would be useful to use the similarity of the two approaches to obtain a physical description of the IBA constants. Use of the IBA-2 approach might also prove illuminating, since it should identify the contributions of the neutron and proton degrees of freedom, analogous to the method of Greiner
Zhernov, A A; Zhernov, An A
2012-03-01
Experience of treatment of 24 patients, suffering neck deformity and contracture, using stretched flaps with axial type of blood circulation, was summarized. In total 43 expanders were implanted. The cutaneo-fascial flaps stretching was performed in the neck and thorax. In all the flaps a nutrition artery was included. The neck-brachial flaps, including supraclavicular artery, were applied in 25 (58.1%) patients, the neck-thoracic flaps, using superficial neck artery--in 12 (27.91%), the occipital-neck flaps on a musculocutaneous perforating vessels of occipital artery--in 6 (13.95%). The methods of the expander implantation, the stretching, transposition regimes of plastic material and its fixation were elaborated. The donor sites were closed using stretched tissues, left in place after formation of flaps. Flaps were fixed, using mechanical method of the tissues connection with duplicature formation from deepidermized portion of cicatrix or with polypropylene mesh, which played a role of a dense framework. Then a strong connective tissue bolt was formed, securely fixing transposedstretched tissues. While application of a complex-component vascularized flaps a suppuration have occurred in 3 (6.97%), partial necrosis--in 2 (4.64%) observations. Inclusion of nutritive vessels permit to form large size flaps with a small risk of necrosis occurrence. The stretched perforant flaps application permits to achieve positive result in 95.3% of observations--in immediate and in 81.82%--in far remote period. PMID:22702123
DEFORMATION SUBSTRUCTURES AND THEIR TRANSITIONS IN LASER SHOCK-COMPRESSED COPPER-ALUMINUM ALLOYS
Meyers, M A; Schneider, M S; Jarmakani, H; Kad, B; Remington, B A; Kalantar, D H; McNaney, J; Cao, B; Wark, J
2007-10-17
It is shown that the short pulse durations (0.1-10 ns) in laser shock compression ensure a rapid decay of the pulse and quenching of the shocked sample in times that are orders of magnitude lower than in conventional explosively driven plate impact experiments. Thus, laser compression, by virtue of a much more rapid cooling, enables the retention of a deformation structure closer to the one existing during shock. The smaller pulse length also decreases the propensity for localization. Copper and copper aluminum (2 and 6 wt% Al) with orientations [001] and [{bar 1}34] were subjected to high intensity laser pulses with energy levels of 70 to 300 J delivered in an initial pulse duration of approximately 3 ns. The [001] and [{bar 1}34] orientations were chosen since they respectively maximize and minimize the number of slip systems with highest resolved shear stresses. Systematic differences of the defect substructure were observed as a function of pressure, stacking-fault energy and crystalline orientation. The changes in the mechanical properties for each condition were compared using micro- and nano-hardness measurements and correlated well with observations of the defect substructure. Three regimes of plastic deformation were identified and their transitions modeled: dislocation cells, stacking-faults, and twins. An existing constitutive description of the slip to twinning transition, based on the critical shear stress, was expanded to incorporate the effect of stacking-fault energy. A new physically-based criterion accounting for stacking-fault energy was developed that describes the transition from perfect loop to partial loop homogeneous nucleation, and consequently from cells to stacking-faults. These calculations predict transitions that are in qualitative agreement with the effect of SFE.
Unlike most intermetallic compounds, polycrystalline YCu, a B2 (CsCl-type) intermetallic, is ductile at room temperature. The mechanisms for this behavior are not fully understood. In situ neutron diffraction was used to investigate whether a stress-induced phase transformation or twinning contribute to the ductility; however, neither mechanism was found to be active in YCu. Surprisingly, this study revealed that the intensities of the diffraction peaks increased after plastic deformation. It is thought that annealing the samples created nearly perfect crystallinity, and subsequent deformation reduced this high degree of lattice coherency, resulting in a modified mosaic structure that decreased or eliminated the extinction effect. Analysis of changes in diffraction peak intensity showed a region of primary plasticity that exhibits significant changes in diffraction behavior. Fully annealed samples initially contain diffracting volumes large enough to follow the dynamical theory of diffraction. When loaded beyond the yield point, dislocation motion disrupts the lattice perfection, and the diffracting volume is reduced to the point that diffraction follows the kinematic theory of diffraction. Since the sample preparation and deformation mechanisms present in this study are common in numerous material systems, this dynamical to kinematic diffraction transition should also be considered in other diffraction experiments. These measurements also suggest the possibility of a new method of investigating structural characteristics
Mailhot, A.; Plumer, M.L.; Caille, A. (Centre de Recherche en Physique du Solide et Departement de Physique, Universite de Sherbrooke, Sherbrooke, Quebec, J1K 2R1 (Canada)); Azaria, P. (Laboratoire de Physique Theorique des Liquides, Universite Pierre et Marie Curie, 4 place Jussieu, 75252 Paris CEDEX 05 (France))
1992-05-01
The influence of biquadratic exchange on the Heisenberg model with strong axial anisotropy is examined for the case of spins on a body-centered tetragonal lattice with competing bilinear exchange interactions along the {ital c} axis. Contrary to the usual axial next-nearest-neighbor Ising model with third-neighbor exchange also included, a low-temperature spin-wave calculation reveals that biquadratic exchange can stabilize the sequence of phases period 3{r arrow}period 2. Mean-field analysis, with support from Monte Carlo simulations, suggests a higher-temperature transition to an incommensurate state. This sequence of phase transitions has recently been observed in UNi{sub 2}Si{sub 2}. The importance of fluctuations is emphasized.
Figiel, Łukasz; Dunne, Fionn P. E.; Buckley, C. Paul
2010-01-01
Layered-silicate nanoparticles offer a cost-effective reinforcement for thermoplastics. Computational modelling has been employed to study large deformations in layered-silicate/poly(ethylene terephthalate) (PET) nanocomposites near the glass transition, as would be experienced during industrial forming processes such as thermoforming or injection stretch blow moulding. Non-linear numerical modelling was applied, to predict the macroscopic large deformation behaviour, with morphology evolution and deformation occurring at the microscopic level, using the representative volume element (RVE) approach. A physically based elasto-viscoplastic constitutive model, describing the behaviour of the PET matrix within the RVE, was numerically implemented into a finite element solver (ABAQUS) using an UMAT subroutine. The implementation was designed to be robust, for accommodating large rotations and stretches of the matrix local to, and between, the nanoparticles. The nanocomposite morphology was reconstructed at the RVE level using a Monte-Carlo-based algorithm that placed straight, high-aspect ratio particles according to the specified orientation and volume fraction, with the assumption of periodicity. Computational experiments using this methodology enabled prediction of the strain-stiffening behaviour of the nanocomposite, observed experimentally, as functions of strain, strain rate, temperature and particle volume fraction. These results revealed the probable origins of the enhanced strain stiffening observed: (a) evolution of the morphology (through particle re-orientation) and (b) early onset of stress-induced pre-crystallization (and hence lock-up of viscous flow), triggered by the presence of particles. The computational model enabled prediction of the effects of process parameters (strain rate, temperature) on evolution of the morphology, and hence on the end-use properties.
Alpha decay and nuclear deformation: the case for favoured alpha transitions of even-even emitters
Alpha decay half-life for ground-state to ground-state transitions of 174 even-even alpha emitters has been calculated from a simple, Gamow-like model in which the quadrupole deformation of the product nucleus (assumed to have an ellipsoidal shape) is taken into account. The assumption made is that before tunnelling through a purely Coulomb potential barrier the two-body system oscillates isotropically, thus giving rise to an equivalent, average polar direction θ0 (referred to the symmetry axis of the ellipsoid) for alpha emission. It is shown that the experimental half-life data are much better reproduced by the present description than in the spherical shaped approximation for the daughter nucleus. (author)
Finck, C; Stezowski, O; Kintz, N; Vivien, JP; Zuber, K; Nourreddine, A; Appelbe, DE; Beausang, CW; Beck, FA; Byrski, T; Courtin, S; Curien, D; de France, G; Duchene, G; Erturk, S; Gall, BJP; Haas, B; Khadiri, N; Pachoud, E; Rigollet, C; Smith, M; Theisen, C; Twin, PJ
1999-01-01
Double step resolved gamma-ray transitions linking the yrast superdeformed (SD) band of Gd-149 to the normal deformed (ND) level scheme have been observed using the EUROGAM phase II spectrometer. The excitation energy of the 47/2(-) SD state above the 7/2(-) ground state has thus been determined to
Chen, Long
2016-01-01
Anomaly-free perturbations of loop quantum cosmology with holonomy corrections reveal a $\\Omega$ -deformed space-time structure, $\\Omega:=1-2\\rho/\\rho_c$, where $\\Omega0$ means a Lorentz-like space. It would be reasonable to give the initial value at the space-time transition point, $\\rho=\\rho_c/2$, but we find it is impossible to define a Minkowski-like vacuum even for large $k$-modes at that time. However if we loose the condition and give the initial value near after $\\Omega=0$, e.g. $\\Omega\\simeq 0.2$, the vacuum state can be well defined and furthermore the slow roll approximation also works well in that region. Both scalar and tensor spectra are considered in the framework of loop quantum cosmology with holonomy corrections. We find that if the energy density is not too small compared with $\\rho_c/2$ when the considered $k$-mode crossing the horizon, effective theory can give a much smaller scalar power spectrum than classical theory and the spectrum of tensor perturbations could blue shift. But when co...
Schubnel, A.; Walker, E.; Thompson, B. D.; Fortin, J.; Guéguen, Y.; Young, R. P.
2006-09-01
Two triaxial compression experiments were performed on Carrara marble at high confining pressure, in creep conditions across the brittle-ductile transition. During cataclastic deformation, elastic wave velocity decrease demonstrated damage accumulation (microcracks). Keeping differential stress constant and reducing normal stress induced transient creep events (i.e., fast accelerations in strain) due to the sudden increase of microcrack growth. Tertiary creep and brittle failure followed as damage came close to criticality. Coalescence and rupture propagation were slow (60-200 seconds with ~150 MPa stress drops and millimetric slips) and radiated little energy in the experimental frequency range (0.1-1 MHz). Microstructural analysis pointed out strong interactions between intra-crystalline plastic deformation (twinning and dislocation glide) and brittle deformation (microcracking) at the macroscopic level. Our observations highlight the dependence of acoustic efficiency on the material's rheology, at least in the ultrasonic frequency range, and the role played by pore fluid diffusion as an incubation process for delayed failure triggering.
Magnetic transition induced by mechanical deformation in Fe60Al40−xSix ternary alloys
Highlights: • Fe60Al40−xSix alloys were disordered by means of planetary ball milling technique. • Paramagnetic to ferromagnetic transition is observed with disordering. • Si addition hinders the disordering process and the increase of the lattice parameter. • Si addition promotes the paramagnetic to ferromagnetic transition. -- Abstract: We have used Mössbauer spectroscopy and X-ray diffraction to study the influence of different Al/Si ratios on the structural and magnetic properties of the mechanically deformed Fe60Al40−xSix alloys. The results indicate that ternary alloys also present the magnetic transition with disordering observed in binary Fe60Al40 alloys. Besides, Si introduction has two opposite contributions. From a structural point of view, hinders the disordering process, but, from a magnetic point of view promotes the magnetic transition
An expression of reduced probability of electrical transitions in deformed odd-A nuclei is obtained within the quasiparticle-phonon model. The commutation relations between quasiparticle and phonon operators, taking into account the quasiparticle structure of phonons, are used. It is shown that corrections arising in such approach can result in a significant change in the reduced probability value (1.5-2 times)
Moon, Chang-Bum
2016-01-01
We study a global nuclear structure in the framework of experimental observables. With the aid of large nuclear structure data at the national nuclear data center, NNDC, we present the distinctive systematic patterns emerged in the first 2+ excited energies, E(2+) and their energy ratios to the first 4+ levels, R = E(4+)/E(2+), in the even-even nuclei, over 50 < Z < 82 for protons, and 50 < N < 126 for neutrons. We introduce the so-called pseudo-shell configurations from the subshells mixture in order to explain a semi-double shell closure, a shape phase transition, and a reinforced deformation. It is found that the reinforced deformation arises when Z = 64 or 66 correlates with N = 90 and reaches its maximum, indicating R = 3.3. Such a saturated reinforced deformation spans over Z = 58 to 72 and N = 100 to 106 as showing its center at Z = 64 or 66 and at N = 102 or 104. We define this reinforced deformation 'a ferro-deformation' like a ferro-magnetism in condensed matter physics. The shape coexis...
Chabab, M.; Batoul, A. El; Lahbas, A.; Oulne, M.
2016-01-01
In this paper, we present a theoretical study of a conjonction of $\\gamma$-rigid and $\\gamma$-stable collective motions in critical point symmetries of the phase transitions from spherical to deformed shapes of nuclei using exactly separable version of the Bohr Hamiltonian with deformation-dependent mass term. The deformation-dependent mass is applied simultaneously to $\\gamma$-rigid and $\\gamma$-stable parts of this famous collective Hamiltonian. Moreover, the $\\beta$ part of the problem is ...
Vattré, A.; Denoual, C.
2016-07-01
A thermodynamically consistent framework for combining nonlinear elastoplasticity and multivariant phase-field theory is formulated at large strains. In accordance with the Clausius-Duhem inequality, the Helmholtz free energy and time-dependent constitutive relations give rise to displacive driving forces for pressure-induced martensitic phase transitions in materials. Inelastic forces are obtained by using a representation of the energy landscape that involves the concept of reaction pathways with respect to the point group symmetry operations of crystal lattices. On the other hand, additional elastic forces are derived for the most general case of large strains and rotations, as well as nonlinear, anisotropic, and different elastic pressure-dependent properties of phases. The phase-field formalism coupled with finite elastoplastic deformations is implemented into a three-dimensional Lagrangian finite element approach and is applied to analyze the iron body-centered cubic (α-Fe) into hexagonal close-packed (ɛ-Fe) phase transitions under high hydrostatic compression. The simulations exhibit the major role played by the plastic deformation in the morphological and microstructure evolution processes. Due to the strong long-range elastic interactions between variants without plasticity, a forward α → ɛ transition is energetically unfavorable and remains incomplete. However, plastic dissipation releases considerably the stored strain energy, leading to the α ↔ ɛ ↔α‧ (forward and reverse) polymorphic phase transformations with an unexpected selection of variants.
Stoitsov, M V; Kortelainen, M; Michel, N; Nam, H; Olsen, E; Sarich, J; Wild, S
2012-01-01
We describe the new version 2.00c of the code HFBTHO that solves the nuclear Skyrme Hartree-Fock (HF) or Skyrme Hartree-Fock-Bogolyubov (HFB) problem by using the cylindrical transformed deformed harmonic-oscillator basis. In the new version, we have implemented the following features: (i) the modified Broyden method for non-linear problems, (ii) optional breaking of reflection symmetry, (iii) calculation of axial multipole moments, (iv) finite temperature formalism for the HFB method, (v) linear constraint method based on the approximation of the Random Phase Approximation (RPA) matrix for multi-constraint calculations, (vi) blocking of quasi-particles in the Equal Filling Approximation (EFA), (vii) framework for generalized energy density with arbitrary density-dependences, and (viii) shared memory parallelism via OpenMP pragmas.
张麒蛰; 卓卫东; 范立础
2013-01-01
In order to obtain the axial bearing capacity of a batter pile , the calculation formula for the axially bearing capacity of a batter pile was deduced based on the non-uniform distribution char-acteristics of the friction resistance around the batter pile shaft and the mechanism of pile -soil deformation compatibility .The results calculated by the proposed formula and the method given by the design code of pile were compared to explore the influence of the factors , such as pile inclina-tion, diameter, length and utmost friction resistance around pile shaft , on axial bearing capacity. The calculated results showed that the value of the pile axially bearing capacity calculated by the proposed formula decreased with the increase of pile inclination .For different pile diameters , the pile axially bearing capacity was 7%smaller than that calculated by the code's formula.The shorter of the pile length or the lesser of the utmost friction resistance of the pile was , the smaller bearing capacity calculated by the code's formula was than the values calculated by the proposed formula . Finally , with the increase of the pile length or utmost friction resistance , the value of bearing capaci-ty calculated by this proposed formula was greater than the value calculated by the code's formula. The proposed formula also takes into account of the influence of pile inclination and the mechanism of pile-soil deformation compatibility .It can be a reference to calculate axial bearing capacity of bat-ter piles.%为进一步研究斜桩轴向承载力计算方法，基于斜桩的桩周摩阻力不均匀分布的特性和桩-土受力变形协调的原则，推导了斜桩轴向承载力计算公式，通过对比本文公式与规范公式的计算结果，揭示了桩身倾角、桩径、桩长和桩侧极限摩阻力等因素对斜桩轴向容许承载力的影响规律。结果表明：鉴于规范公式未考虑斜桩桩身倾角对承载力的影响，本文公式计算得
Robin, J
2003-12-01
While the superdeformation phenomenon has been observed many times in different mass regions, the excitation energy and angular momentum are not known for most of the superdeformed bands, mainly in the A {approx} 150 mass region. We have thus undertaken the search for and study of linking transitions between super and normal deformed potential wells in the Tb{sup 151} nucleus with the EUROBALL-IV spectrometer based at the subatomic research institute of Strasbourg. This nucleus presents the peculiarity of having an excited superdeformed band identical to the yrast one of Dy{sup 152}, which has recently been linked to normal deformed states. As the Dy{sup 152} nucleus exhibits a shape coexistence in the first potential well, we have also searched for collective rotational bands with prolate but moderate shape, coexisting with the oblate structure of Tb{sup 151}. The discovery of new superdeformed bands in the Tb{sup 151,152} isotopes, the extension to lower and higher spins of the previously known bands, and mean field calculations with a deformed Woods-Saxon potential have contributed to improve our knowledge as well as raise new questions on the orbitals configuration assignments of these bands. (author)
无
2007-01-01
OM (optical microscope)/TEM (transmission electron microscope) micro- and submicrostructural analysis of hornblende rocks sheared at high temperatures from the Diancangshan area, western Yunnan reveals evidence for deformation in the brittle-ductile transition of hornblende at middle crustal level (about 637℃ and 0.653 GPa) and mechanisms of deformation in the transitional regime are further discussed. Sheared hornblende rocks at middle crustal level have typical mylonitic microstructures, shown by coarse porphyroclasts and fine matrix grains. Different mineral phases in the rocks show distinct deformation characteristics. Hornblende and feldspar grains are intensely deformed with obvious grainsize reduction, but quartz grains are recrystallized dominantly by grain growth. Hornblende grains show typical brittle-ductile transition nature. Initial crystallographic orientations of porphyroclasts have strong effects on the behavior of grains during deformation. There are mainly two types of porphyroclasts, type I "hard" porphyroclasts and type II "soft" porphyroclasts, with [001] perpendicular and parallel to external shear stresses respectively. "Hard" porphyroclasts generally occur as competent grains that are rarely deformed or sometimes deformed by fracturing and dislocation tangling. "Soft" porphyroclasts are highly deformed primarily by dislocation tangling (as shown in the cores of the porphyroclasts), but twinning, dislocation glide and climb probably due to hydrolytic weakening also contribute to dynamic recrystallization of the porphyroclasts into fine grains in the matrix. The micro- and submicrostructures of the two types of porphyroclasts and fine-grained matrix provide powerful evidence for the behavior of brittle-ductile transition of hornblende grains. It is concluded that twinning nucleation is one of the most important processes that operate during dynamic recrystallization of hornblende crystals at the brittle-ductile transition. (100) [001] twin
Quantum phase transitions in odd-nuclei are investigated within the framework of the interacting boson-fermion model with a description based on the concept of intrinsic states. We consider the case of a single j=9/2 odd-particle coupled to an even-even boson core that performs a transition from spherical to deformed prolate and to deformed gamma-unstable shapes varying a control parameter in the boson Hamiltonian. The effect of the coupling of the odd particle to this core is discussed along the shape transition and, in particular, at the critical point. (authors)
While the superdeformation phenomenon has been observed many times in different mass regions, the excitation energy and angular momentum are not known for most of the superdeformed bands, mainly in the A ∼ 150 mass region. We have thus undertaken the search for and study of linking transitions between super and normal deformed potential wells in the Tb151 nucleus with the EUROBALL-IV spectrometer based at the subatomic research institute of Strasbourg. This nucleus presents the peculiarity of having an excited superdeformed band identical to the yrast one of Dy152, which has recently been linked to normal deformed states. As the Dy152 nucleus exhibits a shape coexistence in the first potential well, we have also searched for collective rotational bands with prolate but moderate shape, coexisting with the oblate structure of Tb151. The discovery of new superdeformed bands in the Tb151,152 isotopes, the extension to lower and higher spins of the previously known bands, and mean field calculations with a deformed Woods-Saxon potential have contributed to improve our knowledge as well as raise new questions on the orbitals configuration assignments of these bands. (author)
Lajnef, N.; Burgueño, R.; Borchani, W.; Sun, Y.
2014-05-01
A major obstacle limiting the development of deployable sensing and actuation solutions is the scarcity of power. Converted energy from ambient loading using piezoelectric scavengers is a possible solution. Most of the previously developed research focused on vibration-based piezoelectric harvesters which are typically characterized by a response with a narrow natural frequency range. Several techniques were used to improve their effectiveness. These methods focus only on the transducer’s properties and configurations, but do little to improve the stimuli from the source. In contrast, this work proposes to focus on the input deformations generated within the structure, and the induction of an amplified amplitude and up-converted frequency toward the harvesters’ natural spectrum. This paper introduces the concept of using mechanically-equivalent energy converters and frequency modulators that can transform low-amplitude and low-rate service deformations into an amplified vibration input to the piezoelectric transducer. The introduced concept allows energy conversion within the unexplored quasi-static frequency range (≪1 Hz). The post-buckling behavior of bilaterally constrained columns is used as the mechanism for frequency up-conversion. A bimorph cantilever polyvinylidene fluoride (PVDF) piezoelectric beam is used for energy conversion. Experimental prototypes were built and tested to validate the introduced concept and the levels of extractable power were evaluated for different cases under varying input frequencies. Finally, finite element simulations are reported to provide insight into the scalability and performance of the developed concept.
SiC/SiC composites are candidate materials for in-core components of future nuclear reactors. The analysis of these structures using numerical simulations requires material constitutive laws. The present work focuses on understanding the deformation mechanisms of these materials in order to build a constitutive model able to predict their stress-strain response under complex loadings. An extensive characterization of the mechanical behaviour of SiC/SiC multi-layered tubes - similar to fuel cladding concepts - was carried out, using tension internal pressure, tension-torsion and bending tests, that allowed to build an important experimental basis for the understanding of the mechanisms and the identification of constitutive laws. In-situ and post-failure observations have allowed quantifying the orientation of surface matrix cracks as a function of the loading type. Full-field measurements using Digital Image Correlation at the tow scale brought precise information on the composite surface kinematics, such as the crack opening or the deformation of the matrix fragments. These measurements also evidence the importance of the tow reorientation, that could explain specific features of the macroscopic behaviour because of its coupling with matrix cracking. Finally, these experimental data allowed to build a constitutive model, identified on only four uniaxial tests, able to predict satisfactorily the macroscopic behaviour under several biaxial loadings. The correct prediction of local quantities, such as the characteristics of the matrix cracking in tension, has also been verified. (author)
A major obstacle limiting the development of deployable sensing and actuation solutions is the scarcity of power. Converted energy from ambient loading using piezoelectric scavengers is a possible solution. Most of the previously developed research focused on vibration-based piezoelectric harvesters which are typically characterized by a response with a narrow natural frequency range. Several techniques were used to improve their effectiveness. These methods focus only on the transducer’s properties and configurations, but do little to improve the stimuli from the source. In contrast, this work proposes to focus on the input deformations generated within the structure, and the induction of an amplified amplitude and up-converted frequency toward the harvesters’ natural spectrum. This paper introduces the concept of using mechanically-equivalent energy converters and frequency modulators that can transform low-amplitude and low-rate service deformations into an amplified vibration input to the piezoelectric transducer. The introduced concept allows energy conversion within the unexplored quasi-static frequency range (≪1 Hz). The post-buckling behavior of bilaterally constrained columns is used as the mechanism for frequency up-conversion. A bimorph cantilever polyvinylidene fluoride (PVDF) piezoelectric beam is used for energy conversion. Experimental prototypes were built and tested to validate the introduced concept and the levels of extractable power were evaluated for different cases under varying input frequencies. Finally, finite element simulations are reported to provide insight into the scalability and performance of the developed concept. (paper)
CAI Ying-Xiang; XU Rui
2010-01-01
@@ A new transition path(γangle deformation path)is put forward and used to characterize the wurtzite-rocksalt transition in AlN.The enthalpy surface and the contour plot of enthalpy difference at equilibrium pressure are obtained by first-principles pseudopotential method within the generalized gradient approximation.The phase transition is needed to overcome two barriers and a metaphase arises between them.The total barrier height is0.26eV.
Nucleus /sup 136/Sm and the transition to a deformed regime at N = 76--74
Using γ-ray spectroscopy methods, excited states up to spin 14+ have been identified in the neutron-deficient nucleus /sub <1//sub 62//sup 36/Sm/sub 74/. Mean lifetime measurements give β = 0.30 showing that the N = 74 = 82-8 neutron number marks the limit of strong nuclear deformation, similarly to the symmetric N = 90 = 82+8
Nucleus /sup 136/Sm and the transition to a deformed regime at N = 76--74
Soramel, F.; Lunardi, S.; Beghini, S.; Morando, M.; Signorini, C.; Meczynski, W.; Fortuna, G.; Montagnoli, G.; Stefanini, A.M.
1988-07-01
Using ..gamma..-ray spectroscopy methods, excited states up to spin 14/sup +/ have been identified in the neutron-deficient nucleus /sub <1//sub 62//sup 36/Sm/sub 74/. Mean lifetime measurements give ..beta.. = 0.30 showing that the N = 74 = 82-8 neutron number marks the limit of strong nuclear deformation, similarly to the symmetric N = 90 = 82+8.
Sébille-Schück, C; Genevey-Rivier, J; Höglund, A; Huck, A; Knipper, A; Richard-Serre, Claude; Walter, G
1976-01-01
A level scheme is proposed for neutron deficient /sup 185/Ir obtained by the decay of /sup 185/Pt produced with the ISOLDE on-line separator (CERN). This level scheme is compared to those of heavier mass iridium nuclei where the negative parity levels had been interpreted in the asymmetric-rotor-plus-particle model. In /sup 185/Ir similar systems of levels appear with a stronger prolate deformation of the nucleus. They seem correctly described by coupling an odd-particle (or a hole) to a symmetric rotor.
Low temperature irradiation of crystalline materials is known to result in hardening and loss of ductility, which limits the usefulness of candidate materials in harsh nuclear environments. In body-centered cubic (bcc) metals, this mechanical property degradation is caused by the interaction of in-grown dislocations with irradiation defects, particularly small dislocation loops resulting from the microstructural evolution of displacement cascades. In this paper, we perform dislocation dynamics simulations of bcc Fe containing various concentrations of dislocation loops produced by irradiation in an attempt to gain insight into the processes that lead to hardening and embrittlement. We find that a transition from homogenous to highly localized deformation occurs at a critical loop density. Above it, plastic flow proceeds heterogeneously, creating defect-free channels in its wake. We find that channel initiation and size are mediated by loop coalescence resulting from elastic interactions with moving dislocations.
Phase transitions in the $sdg$ interacting boson model
P. Van Isacker(Ganil, Caen, France;); Bouldjedri, A.; Zerguine, S.
2010-01-01
19 pages, 5 figures, submitted to Nuclear Physics A A geometric analysis of the $sdg$ interacting boson model is performed. A coherent-state is used in terms of three types of deformation: axial quadrupole ($\\beta_2$), axial hexadecapole ($\\beta_4$) and triaxial ($\\gamma_2$). The phase-transitional structure is established for a schematic $sdg$ hamiltonian which is intermediate between four dynamical symmetries of U(15), namely the spherical ${\\rm U}(5)\\otimes{\\rm U}(9)$, the (prolate and ...
Heineck, James; Schairer, Edward; Ramasamy, Manikandan; Roozeboom, Nettie
2016-01-01
This paper describes simultaneous optical measurements of a sub-scale helicopter rotor in the U.S. Army Hover Chamber at NASA Ames Research Center. The measurements included thermal imaging of the rotor blades to detect boundary layer transition; retro-reflective background-oriented schlieren (RBOS) to visualize vortices; and stereo photogrammetry to measure displacements of the rotor blades, to compute spatial coordinates of the vortices from the RBOS data, and to map the thermal imaging data to a three-dimensional surface grid. The test also included an exploratory effort to measure flow near the rotor tip by tomographic particle image velocimetry (tomo PIV)an effort that yielded valuable experience but little data. The thermal imaging was accomplished using an image-derotation method that allowed long integration times without image blur. By mapping the thermal image data to a surface grid it was possible to accurately locate transition in spatial coordinates along the length of the rotor blade.
Haerinck, Tom; Hirt, Ann M.; Debacker, Timothy N.; Sintubin, Manuel
2014-05-01
The anisotropy of magnetic susceptibility (AMS) of progressively deformed, fine-grained sedimentary rocks is determined for different tectonometamorphic settings in Central Armorica (Brittany, France). Low-temperature AMS and high-field torque magnetometry on a representative selection of samples indicate that the magnetic fabric is dominantly paramagnetic and the ferromagnetic (s.l.) contribution can be neglected. The AMS documents a progressive transition of intermediate fabrics to tectonic fabrics and increasingly stronger developed tectonic fabrics. An integrated magnetic-mineralogical approach is performed in order to assess whether we can use this evolution as a quantitative indicator for the intensity of cleavage development in Central Armorica. During the magnetic fabric transition, the maximum susceptibility axis (K1) remains stationary oriented parallel to the bedding - cleavage intersection, whereas the minimum susceptibility axis (K3) orientation distribution changes from a moderate girdle distribution in the intermediate fabric types, to a strongly clustered distribution parallel to the cleavage pole for the tectonic fabric types. A Woodcock two-axis ratio plot is used to evaluate this change in K3 distribution. This shows a regional pattern with intermediate fabrics in the southern part of Central Armorica and tectonic fabrics in the northern part of Central Armorica. Quantitative analysis of the observed magnetic fabrics shows that the fabric transition described above is accompanied by an evolution from prolate susceptibility ellipsoids with a relatively low degree of anisotropy to oblate ellipsoid with an increasingly higher degree of anisotropy. In a graph of the shape parameter T against the corrected degree of anisotropy PJ, this evolution has a hockey-stick shaped pattern with the vertical branch reflecting the actual transition from intermediate to tectonic fabric type and the horizontal branch reflecting progressively stronger developed
Stoitsov, M. V.; Schunck, N.; Kortelainen, M.; Michel, N.; Nam, H.; Olsen, E.; Sarich, J.; Wild, S.
2013-06-01
We describe the new version 2.00d of the code HFBTHO that solves the nuclear Skyrme-Hartree-Fock (HF) or Skyrme-Hartree-Fock-Bogoliubov (HFB) problem by using the cylindrical transformed deformed harmonic oscillator basis. In the new version, we have implemented the following features: (i) the modified Broyden method for non-linear problems, (ii) optional breaking of reflection symmetry, (iii) calculation of axial multipole moments, (iv) finite temperature formalism for the HFB method, (v) linear constraint method based on the approximation of the Random Phase Approximation (RPA) matrix for multi-constraint calculations, (vi) blocking of quasi-particles in the Equal Filling Approximation (EFA), (vii) framework for generalized energy density with arbitrary density-dependences, and (viii) shared memory parallelism via OpenMP pragmas. Program summaryProgram title: HFBTHO v2.00d Catalog identifier: ADUI_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADUI_v2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public License version 3 No. of lines in distributed program, including test data, etc.: 167228 No. of bytes in distributed program, including test data, etc.: 2672156 Distribution format: tar.gz Programming language: FORTRAN-95. Computer: Intel Pentium-III, Intel Xeon, AMD-Athlon, AMD-Opteron, Cray XT5, Cray XE6. Operating system: UNIX, LINUX, WindowsXP. RAM: 200 Mwords Word size: 8 bits Classification: 17.22. Does the new version supercede the previous version?: Yes Catalog identifier of previous version: ADUI_v1_0 Journal reference of previous version: Comput. Phys. Comm. 167 (2005) 43 Nature of problem: The solution of self-consistent mean-field equations for weakly-bound paired nuclei requires a correct description of the asymptotic properties of nuclear quasi-particle wave functions. In the present implementation, this is achieved by using the single-particle wave functions
Barnhoorn, Auke; Verheij, Jeroen; Frehner, Marcel; Zhubayev, Alimzhan; Houben, Maartje
2016-04-01
The transition from elastic to inelastic deformation occurs at the yield point in a stress-strain diagram. This yield point expresses the moment when a material undergoes permanent deformation and is marked by the onset of fracturing in the brittle field at relatively low pressures and temperatures or the onset of dislocation and/or diffusional creep processes in the ductile field at higher temperatures and pressures. Detection of this transition in materials under stress using an indirect measurement technique is crucial to predict imminent failure, loss of material integrity, or of approaching release of energy by seismic rupture. Here we use a pulse transmission method at ultrasonic frequencies to record the change in acoustic wave form across the transition from elastic to inelastic deformation in a rock-fracturing experiment. In particular, we measure both the acoustic wave velocity and attenuation with increasing strain from the elastic regime all the way to macroscopic failure. Our results show that the transition from elastic to inelastic deformation coincides with a minimum in attenuation. Below this minimum, pre-existing microfractures close, leading to a reduction of attenuation. Above this minimum, formation of new microfractures occurs and attenuation increases until peak stress conditions, at which larger fractures are formed and the rock starts to lose its strength and integrity. At the same time, the acoustic wave velocity continues to increase across the transition from elastic to inelastic deformation; hence the acoustic velocity is not a valid indicator for this elastic to inelastic transition. We propose that analysis of attenuation, not velocity, of acoustic waves through stressed materials may thus be used, for example, to detect imminent failure in materials, onset of crack formation in pipes or the cement casing in boreholes, or onset of fracturing in the near wellbore area. On a larger scale, attenuation monitoring may help predict the
Classes of β-γ mixing and E0 transitions in deformed nuclei
We investigate the effects of β-γ mixing using branching ratios between the 2γ+ level and the ground state band in well-deformed nuclei. We find that the deviations from the well-known Alaga rules vary as a function of the energy separation between the 2γ+ and 2β+ levels. For nuclei where these two intrinsic excitations are nearly degenerate, we find two classes of behavior. For one of those, the systematics can be reproduced in a simple bandmixing formalism but only with an anomalously strong interaction strength between the 2γ+ and 2β+ levels, on the order of tens of keV. This result is supported by X(E0/E2;2γ+→21+) values that are large for these nuclei (where measured), indicating significant K=0 components in the 2γ+ levels. In the other class, there is virtually no mixing. These nuclei have previously been associated with near-SU(3) structure
Hauschild, K.; Bernstein, L.A.; Becker, J.A. [Lawrence Livermore National Lab., CA (United States)] [and others
1996-12-31
The observation of one-step `primary` gamma-ray transitions directly linking the superdeformed (SD) states to the normal deformed (ND) low-lying states of known excitation energies (E{sub x}), spins and parities (J{sup {pi}}) is crucial to determining the E{sub x} and J{sup {pi}} of the SD states. With this knowledge one can begin to address some of the outstanding problems associated with SD nuclei, such as the identical band issue, and one can also place more stringent restrictions on theoretical calculations which predict SD states and their properties. Brinkman, et al., used the early implementation of the GAMMASPHERE spectrometer array (32 detectors) and proposed a single, candidate {gamma} ray linking the {sup 194}Pb yrast SD band to the low-lying ND states in {sup 194}Pb. Using 55 detectors in the GAMMASPHERE array Khoo, et al., observed multiple links between the yrast SD band in {sup 194}Hg and the low-lying level scheme and conclusively determined E{sub x} and J of the yrast SD states. Here the authors report on an experiment in which Gammasphere with 88 detectors was used and the E{sub x} and J{sup {pi}} values of the yrast SD states in {sup 194}Pb were uniquely determined. Twelve one-step linking transitions between the yrast SD band and low-lying states in {sup 194}Pb have been identified, including the transition proposed by Brinkman. These transitions have been placed in the level scheme of {sup 194}Pb using coincidence relationships and agreements between the energies of the primary transitions and the energy differences in level spacings. Furthermore, measurements of angular asymmetries have yielded the multipolarities of the primaries which have allowed J{sup {pi}} assignments of the {sup 194}Pb SD states to be unambiguously determined for the first time without a priori assumptions about the character of SD bands. A study performed in parallel to this work using the EUROGAM-II array reports similar, but somewhat less extensive, results.
Absolute El Transition Probabilities in the Deformed Nuclei {sup 177}Yb and {sup 1}
Malmskog, Sven G.
1964-08-15
The absolute E1-transition probabilities have been measured for two 7/2{sup -} (514) levels populated from the short-lived isomers {sup 177m}Yb (6.4 sec) and {sup 179m}Hf (18.6 sec), a delayed coincidence set up being used for the purpose. This gave a half life of T{sub 1/2} = (4.48 {+-} 0.08)x10{sup -9} sec for the 104 keV level in {sup 177}Yb and T{sub 1/2} = (1.86 {+-} 0.05)x10{sup -9} sec for the 217 keV level in {sup 179}Hf. The result has been compared with the calculations made by Nilsson. The effect of the pairing correlation has also been taken into account. An agreement with the experimental values to within a factor of three is obtained. An extrapolated estimate of the half life for the 408.9 keV 7/2{sup -} (514) level in {sup 181}W gives 3x10{sup -11} sec.
Absolute El Transition Probabilities in the Deformed Nuclei 177Yb and Hf179
The absolute E1-transition probabilities have been measured for two 7/2- (514) levels populated from the short-lived isomers 177mYb (6.4 sec) and 179mHf (18.6 sec), a delayed coincidence set up being used for the purpose. This gave a half life of T1/2 = (4.48 ± 0.08)x10-9 sec for the 104 keV level in 177Yb and T1/2 = (1.86 ± 0.05)x10-9 sec for the 217 keV level in 179Hf. The result has been compared with the calculations made by Nilsson. The effect of the pairing correlation has also been taken into account. An agreement with the experimental values to within a factor of three is obtained. An extrapolated estimate of the half life for the 408.9 keV 7/2- (514) level in 181W gives 3x10-11 sec
New flows and instabilities are presented for a ferrofluid drop contained in glass Hele-Shaw cells with simultaneously applied in-plane clockwise rotating and DC axial uniform magnetic fields. When a ferrofluid drop is stressed by a uniform DC axial magnetic field, up to ∼250 G in 0.9-1.4 mm gap Hele-Shaw cells, the drop forms a labyrinth pattern. With subsequent application of an in-plane uniform rotating magnetic field, up to ∼100 G rms at frequency 20-40 Hz, smooth spirals form from viscous shear due to ferrofluid flow. If the rotating magnetic field is applied first, the drop is held together without a labyrinth. Gradual increase of the DC axial magnetic field, to a critical magnetic field value, results in an abrupt phase transformation from a large drop to many small discrete droplets. A preliminary minimum magnetization and surface energy analysis is presented to model the phase transformation
Inverse problem for axial-deformed potentials
In the literature about Inverse Problems there are no tractable methods for construction of nonspherical potentials from the asymptotic wave function. This problem turned out to be solved in special cases. The methods of reconstruction from scattering data are given for the class of potentials admitting the separation of variables in spheroidal coordinates. This is the first case when the agorithms of the inverse problem solution for spherically-nonsymmetrical local potentials can practically be realised. The modifications of the formalisms of Regge-Newton-Sabatier and finite-difference approximation of Hooshyar-Rasavy are considered
Legarra, E., E-mail: estibaliz.legarra@ehu.es [Dpto. Electricidad y Electronica, Universidad del Pais Vasco (UPV/EHU), CP. 644, 48080 Bilbao (Spain); Apiñaniz, E. [Dpto. Fisica Aplicada I, Universidad del Pais Vasco, Alameda de Urquijo s/n, 48013 Bilbao (Spain); Plazaola, F. [Dpto. Electricidad y Electronica, Universidad del Pais Vasco (UPV/EHU), CP. 644, 48080 Bilbao (Spain); Jimenez, J.A. [Centro Nacional de Investigaciones Metalurgicas (CENIM), Avda. Gregorio del amo 8, 28040 Madrid (Spain)
2014-02-15
Highlights: • Fe{sub 60}Al{sub 40−x}Si{sub x} alloys were disordered by means of planetary ball milling technique. • Paramagnetic to ferromagnetic transition is observed with disordering. • Si addition hinders the disordering process and the increase of the lattice parameter. • Si addition promotes the paramagnetic to ferromagnetic transition. -- Abstract: We have used Mössbauer spectroscopy and X-ray diffraction to study the influence of different Al/Si ratios on the structural and magnetic properties of the mechanically deformed Fe{sub 60}Al{sub 40−x}Si{sub x} alloys. The results indicate that ternary alloys also present the magnetic transition with disordering observed in binary Fe{sub 60}Al{sub 40} alloys. Besides, Si introduction has two opposite contributions. From a structural point of view, hinders the disordering process, but, from a magnetic point of view promotes the magnetic transition.
Euclidean dynamical symmetry in nuclear shape phase transitions
The Euclidean dynamical symmetry hidden in the critical region of nuclear shape phase transitions is revealed by a novel algebraic F(5) description. With a nonlinear projection, it is shown that the dynamics in the critical region of the spherical–axial deformed and the spherical–γ-soft shape phase transitions can indeed be manifested by this description, which thus provides a unified symmetry-based interpretation of the critical phenomena in the region.
Lee, Subin; Im, Jiseong; Yoo, Youngdong; Bitzek, Erik; Kiener, Daniel; Richter, Gunther; Kim, Bongsoo; Oh, Sang Ho
2014-01-01
Mechanical response of metal nanowires has recently attracted a lot of interest due to their ultra-high strengths and unique deformation behaviours. Atomistic simulations have predicted that face-centered cubic metal nanowires deform in different modes depending on the orientation between wire axis and loading direction. Here we report, by combination of in situ transmission electron microscopy and molecular dynamic simulation, the conditions under which particular deformation mechanisms take place during the uniaxial loading of [110]-oriented Au nanowires. Furthermore, by performing cyclic uniaxial loading, we show reversible plastic deformation by twinning and consecutive detwinning in tension and compression, respectively. Molecular dynamics simulations rationalize the observed behaviours in terms of the orientation-dependent resolved shear stress on the leading and trailing partial dislocations, their potential nucleation sites and energy barriers. This reversible twinning-detwinning process accommodates large strains that can be beneficially utilized in applications requiring high ductility in addition to ultra-high strength. PMID:24398783
The energy levels and reduced probabilities of electric dipole, quadrupole and octupole transitions measured in the Coulomb excitation of 226Ra are analyzed in the framework of the soft axial-symmetric rotator model with quadrupole and octupole deformations. The calculated values are in good agreement with experimental data. (author). 11 refs., 2 figs
Kunle Adegoke; Helmut Büttner
2010-02-01
We have investigated the one-dimensional spin-1/2 axial next-nearest-neighbour Ising (ANNNI) model in two orthogonal magnetic fields at zero temperature. There are four different possible ground state configurations for the ANNNI model in a longitudinal field, in the thermodynamic limit. The inclusion of a transverse field introduces quantum fluctuations which destroy the existing spin order along certain critical lines. The effects of the fluctuations in three of the four ordered regions were investigated using the finite-size scaling technique. The phase boundaries of the ANNNI model in two orthogonal magnetic fields were thus determined numerically. For certain limits of the Hamiltonian we compared the obtained results with the existing literature and our results were in good agreement with the results in the existing literature.
V. D. Petrenko
2014-07-01
Full Text Available Purpose. In the section of changes geotechnical conditions of spondylov’s clay to buchatskiy sands may have significant structural deformation of running tunnels. It is necessary to identify the cause of deformities develop ways to minimize and based modeling and calculations to prove the effectiveness of measures to reduce deformation.Methodology. To solve the analysis problem of the stress-strain state (SSS of the system «structure array» it was conducted the numerical simulation using the finite element method (FEM. On the basis of the obtained results the graphs were constructed and the dependencies were determined. Findings. The presence of weak water-saturated soils in tray of the tunnel on an area of transition from spondylov’s clay to buchatskiy sand causes significant increasing in strain construction of tunnels and general vibration liquefaction in soil basis. Also change the physical and mechanical characteristics of soils within the frames of tunnels influences on the level of strain state of most frames. Improved strain state settings of tunnels in areas of change soil characteristics of the array (especially at the bottom of casing can be achieved by chemical consolidation of weak soils. Composition of solutions for fixing the weak soils should be determined based on the study of grain size, porosity, and other parameters of physical and mechanical and physical and chemical characteristics of soils.Originality.The basic cause significant strain on transition zone from spondylov’s clay to buchatskiy sands is found, that is explained by saturated phenomenon vibration liquefaction basis under the tunnel.Practical value.The approaches to reduce the strain in the construction of running tunnels in the transition zone from spondylov’s clay to buchatskiy sands are developed, as well as in the area ofthe station «Glybochytska»the Kyiv Metro.
Yang, Chao; Song, Min; Liu, Yong; Ni, Song; Sabbaghianrad, Shima; Langdon, Terence G.
2016-06-01
Nanocrystalline titanium with an average grain size of about 60-70 nm was prepared by high-pressure torsion. The results of hardness and structural evolutions indicate that a strain-induced hardening-softening-hardening-softening behaviour occurs. For coarse-grained titanium, -type dislocation multiplication, twinning and a high pressure-induced α-to-ω phase transformation play major roles to accommodate deformation, leading to a significant strain hardening. As deformation proceeds, dynamic recrystallisation leads to a decrease in dislocation density, especially for -type dislocations, leading to a slight strain softening. The -component dislocation multiplication dominates the deformation when the grain size decreases to 100 nm and -component dislocation multiplication, grain refinement and the α-to-ω phase transformation contribute to the second strain hardening. The following strain softening is attributed to dynamic recovery.
Sugiyama, Mayu; Saitou, Takashi; Kurokawa, Hiroshi; Sakaue-Sawano, Asako; Imamura, Takeshi; Miyawaki, Atsushi; Iimura, Tadahiro
2014-12-01
In multicellular organism development, a stochastic cellular response is observed, even when a population of cells is exposed to the same environmental conditions. Retrieving the spatiotemporal regulatory mode hidden in the heterogeneous cellular behavior is a challenging task. The G1/S transition observed in cell cycle progression is a highly stochastic process. By taking advantage of a fluorescence cell cycle indicator, Fucci technology, we aimed to unveil a hidden regulatory mode of cell cycle progression in developing zebrafish. Fluorescence live imaging of Cecyil, a zebrafish line genetically expressing Fucci, demonstrated that newly formed notochordal cells from the posterior tip of the embryonic mesoderm exhibited the red (G1) fluorescence signal in the developing notochord. Prior to their initial vacuolation, these cells showed a fluorescence color switch from red to green, indicating G1/S transitions. This G1/S transition did not occur in a synchronous manner, but rather exhibited a stochastic process, since a mixed population of red and green cells was always inserted between newly formed red (G1) notochordal cells and vacuolating green cells. We termed this mixed population of notochordal cells, the G1/S transition window. We first performed quantitative analyses of live imaging data and a numerical estimation of the probability of the G1/S transition, which demonstrated the existence of a posteriorly traveling regulatory wave of the G1/S transition window. To obtain a better understanding of this regulatory mode, we constructed a mathematical model and performed a model selection by comparing the results obtained from the models with those from the experimental data. Our analyses demonstrated that the stochastic G1/S transition window in the notochord travels posteriorly in a periodic fashion, with doubled the periodicity of the neighboring paraxial mesoderm segmentation. This approach may have implications for the characterization of the
Mayu Sugiyama
2014-12-01
Full Text Available In multicellular organism development, a stochastic cellular response is observed, even when a population of cells is exposed to the same environmental conditions. Retrieving the spatiotemporal regulatory mode hidden in the heterogeneous cellular behavior is a challenging task. The G1/S transition observed in cell cycle progression is a highly stochastic process. By taking advantage of a fluorescence cell cycle indicator, Fucci technology, we aimed to unveil a hidden regulatory mode of cell cycle progression in developing zebrafish. Fluorescence live imaging of Cecyil, a zebrafish line genetically expressing Fucci, demonstrated that newly formed notochordal cells from the posterior tip of the embryonic mesoderm exhibited the red (G1 fluorescence signal in the developing notochord. Prior to their initial vacuolation, these cells showed a fluorescence color switch from red to green, indicating G1/S transitions. This G1/S transition did not occur in a synchronous manner, but rather exhibited a stochastic process, since a mixed population of red and green cells was always inserted between newly formed red (G1 notochordal cells and vacuolating green cells. We termed this mixed population of notochordal cells, the G1/S transition window. We first performed quantitative analyses of live imaging data and a numerical estimation of the probability of the G1/S transition, which demonstrated the existence of a posteriorly traveling regulatory wave of the G1/S transition window. To obtain a better understanding of this regulatory mode, we constructed a mathematical model and performed a model selection by comparing the results obtained from the models with those from the experimental data. Our analyses demonstrated that the stochastic G1/S transition window in the notochord travels posteriorly in a periodic fashion, with doubled the periodicity of the neighboring paraxial mesoderm segmentation. This approach may have implications for the characterization of
High values of superconducting transition temperature in oxide superconductors are hypothetically attributed to the d-pairing of charge carriers in the Bose condensate. The order parameter of the superconducting state forms the basis for the same representation of the crystallographic symmetry group of the parent phase which is used to transform those components of the order parameter, which describe the spontaneous deformation of the parent phase and form a real crystal. The layering of the crystal is assumed to be an unessential factor, although it may govern the type of pairing in YBa2Cu3O7-δ. This hypothesis is supported by the model calculations which qualitatively agree with the experimental data on the temperatures of phase transitions in YBa2Cu3O7-δ-based solid solutions. 31 refs., 3 figs
Caspersen, K.; Lew, A.; Ortiz, M.; Carter, E.
2003-12-01
At a pressure of approximately 13 GPa iron undergoes a martensitic phase transition from ground state ferro-magnetic bcc to a non-magnetic hcp structure. The exact transformation varies between experiments and is postulated to have a strong dependence on shear stresses during the loading process. To study this shear dependence we have developed a multi-scale model of iron, in which we employ a quantum mechanics based free energy, a kinematically compatible spinodal decomposition of phases, and a dependence on the bcc{}hcp transition path(s). Using this model we see that that the predicted transformation pressure for pure hydrostatic compression is much higher than expected, however with the inclusion of small initial shear deformations we see the predicted transformation pressure drop considerably and into the experimentally determined pressure range.
Xing, Hui; Dong, Xianglei; Wu, Hongjing; Hao, Guanhua; Wang, Jianyuan; Chen, Changle; Jin, Kexin
2016-01-01
We report the results of a phase-field study of degenerate seaweed to tilted dendrite transition and their growth dynamics during directional solidification of a binary alloy. Morphological selection maps in the planes of (G, Vp) and (ε4, Vp) show that lower pulling velocity, weaker anisotropic strength and higher thermal gradient can enhance the formation of the degenerate seaweed. The tip undercooling shows oscillations in seaweed growth, but it keeps at a constant value in dendritic growth. The M-S instability on the tips and the surface tension anisotropy of the solid-liquid interface are responsible for the formation of the degenerate seaweed. It is evidenced that the place where the interfacial instability occurs determines the morphological transition. The transient transition from degenerate seaweed to tilted dendrite shows that dendrites are dynamically preferred over seaweed. For the tilted dendritic arrays with a large tilted angle, primary spacing is investigated by comparing predicted results with the classical scaling power law, and the growth direction is found to be less sensitive to the pulling velocity and the primary spacing. Furthermore, the effect of the initial interface wavelength on the morphological transition is investigated to perform the history dependence of morphological selection. PMID:27210816
Measurement of Local Deformations in Steel Monostrands Using Digital Image Correlation
Winkler, Jan; Fischer, Gregor; Georgakis, Christos T.
2014-01-01
The local deformation mechanisms in steel monostrands have a significant influence on their fatigue life and failure mode. However, the observation and quantification of deformations in monostrands experiencing axial and transverse deformations is challenging because of their complex geometry, di...
Phase transitions in the $sdg$ interacting boson model
Van Isacker, P; Zerguine, S
2009-01-01
A geometric analysis of the $sdg$ interacting boson model is performed. A coherent-state is used in terms of three types of deformation: axial quadrupole ($\\beta_2$), axial hexadecapole ($\\beta_4$) and triaxial ($\\gamma_2$). The phase-transitional structure is established for a schematic $sdg$ hamiltonian which is intermediate between four dynamical symmetries of U(15), namely the spherical ${\\rm U}(5)\\otimes{\\rm U}(9)$, the (prolate and oblate) deformed ${\\rm SU}_\\pm(3)$ and the $\\gamma_2$-soft SO(15) limits. For realistic choices of the hamiltonian parameters the resulting phase diagram has properties close to what is obtained in the $sd$ version of the model and, in particular, no transition towards a stable triaxial shape is found.
Axial force measurement for esophageal function testing.
Gravesen, Flemming H; Funch-Jensen, Peter; Gregersen, Hans; Drewes, Asbjørn Mohr
2009-01-14
The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the "golden standard" for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method. PMID:19132762
Axial force measurement for esophageal function testing
Flemming H Gravesen; Peter Funch-Jensen; Hans Gregersen; Asbjφrn Mohr Drewes
2009-01-01
The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the "golden standard" for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method.
Sternstein, S. S.; Yang, P.
1983-01-01
A new test geometry, referred to as centro-symmetric deformation (CSD), is proposed for characterizing the viscoelastic behavior of the matrix of carbon-epoxy laminates. The sample consists of a thin disk, typically 6-14 plies thick, having a nominal diameter of 30 mm. The disk is freely supported on a circular anvil; the load is applied to the center of the disk using an 8-mm-diameter ball bearing nosepiece. The CSD test geometry provides viscoelastic dispersion data which are independent of the angular orientation of the sample. The test geometry is sufficiently sensitive to matrix changes to allow its use for postcuring, humidity, crosslink density, and other matrix change studies. Test results are presented for a carbon-epoxy laminate.
The purpose of this calculation is to develop axial profiles for estimating the axial variation in burnup of a boiling water reactor (BWR) assembly spent nuclear fuel (SNF) given the average burnup of an assembly. A discharged fuel assembly typically exhibits higher burnup in the center and lower burnup at the ends of the assembly. Criticality safety analyses taking credit for SNF burnup must account for axially varying burnup relative to calculations based on uniformly distributed assembly average burnup due to the under-burned tips. Thus, accounting for axially varying burnup in criticality analyses is also referred to as accounting for the ''end effect'' reactivity. The magnitude of the reactivity change due to ''end effect'' is dependent on the initial assembly enrichment, the assembly average burnup, and the particular axial profile characterizing the burnup distribution. The set of bounding axial profiles should incorporate multiple BWR core designs and provide statistical confidence (95 percent confidence that 95 percent of the population is bound by the profile) that end nodes are conservatively represented. The profiles should also conserve the overall burnup of the fuel assembly. More background on BWR axial profiles is provided in Attachment I
J. Huffer
2004-09-28
The purpose of this calculation is to develop axial profiles for estimating the axial variation in burnup of a boiling water reactor (BWR) assembly spent nuclear fuel (SNF) given the average burnup of an assembly. A discharged fuel assembly typically exhibits higher burnup in the center and lower burnup at the ends of the assembly. Criticality safety analyses taking credit for SNF burnup must account for axially varying burnup relative to calculations based on uniformly distributed assembly average burnup due to the under-burned tips. Thus, accounting for axially varying burnup in criticality analyses is also referred to as accounting for the ''end effect'' reactivity. The magnitude of the reactivity change due to ''end effect'' is dependent on the initial assembly enrichment, the assembly average burnup, and the particular axial profile characterizing the burnup distribution. The set of bounding axial profiles should incorporate multiple BWR core designs and provide statistical confidence (95 percent confidence that 95 percent of the population is bound by the profile) that end nodes are conservatively represented. The profiles should also conserve the overall burnup of the fuel assembly. More background on BWR axial profiles is provided in Attachment I.
Quantum phase transitions in Bose-Fermi systems
Research highlights: → We study quantum phase transitions in a system of N bosons and a single-j fermion. → Classical order parameters and correlation diagrams of quantum levels are determined. → The odd fermion strongly influences the location and nature of the phase transition. → Experimental evidence for the U(5)-SU(3) transition in odd-even nuclei is presented. - Abstract: Quantum phase transitions in a system of N bosons with angular momentum L = 0, 2 (s, d) and a single fermion with angular momentum j are investigated both classically and quantum mechanically. It is shown that the presence of the odd fermion strongly influences the location and nature of the phase transition, especially the critical value of the control parameter at which the phase transition occurs. Experimental evidence for the U(5)-SU(3) (spherical to axially-deformed) transition in odd-even nuclei is presented.
Signatures for axial chromodynamics
Within the context of basic left-right symmetry and the hypothesis of unification of weak, electromagnetic and strong forces at a mass level approximately equal to 104-106 GeV, relatively light ''mass'' axial gluons, confined or liberated, must be postulated. The authors remark that the existence of such ''light'' axial gluons supplementing the familiar vector octet preserves the successes of QCD, both for deep inelastic processes and charmonium physics. Through the characteristic spin-spin force, generated by their exchange, they may even help resolve some of the discrepancies between vector QCD predictions and charmonium physics. The main remark of this note is that if colour is liberated, not only vector but also axial-vector gluons are produced in high-energy e-e+ experiments, e.g. at PETRA and PEP, with fairly large cross-section. Distinctive decay modes of such liberated axial gluons are noted
Surface nanoscale axial photonics
Sumetsky, M.; Fini, J. M.
2011-01-01
Dense photonic integration promises to revolutionize optical computing and communications. However, efforts towards this goal face unacceptable attenuation of light caused by surface roughness in microscopic devices. Here we address this problem by introducing Surface Nanoscale Axial Photonics (SNAP). The SNAP platform is based on whispering gallery modes circulating around the optical fiber surface and undergoing slow axial propagation readily described by the one-dimensional Schr\\"odinger e...
Triaxial projected shell model study of transition probabilities for 134Pr nucleus
The quest to establish stable triaxial shapes in nuclei is being pursued with keen interest during the last about half-a-century. In the initial phases for it, the structures of energy levels at relatively low angular momenta were considered. Generally, the deviations from axially symmetric shape are expected at high spins since the rotational effects are strong for high-j orbitals. The loss of axial symmetry affects a number of observables. For a nucleus having a stable triaxial shape, different moments of inertia are associated with each of the principal axes and the rotational motion is possible about all the three axes. Therefore, the rotational spectra are expected to be richer for stable triaxial nuclei as compared to that for axially symmetric deformed nuclei. There are several empirical observations indicating that axial symmetry is broken in transitional regions and therefore the nuclei in these regions have triaxial shapes
Kumaraswamidhas, L. A.; Rajak, Dipen Kumar; Das, S.
2016-06-01
The objective of this research is to produce superior quality aluminum alloy foam with low relative density and higher resistance against compression deformation. This investigation has studied crash energy capacities of unfilled and filled aluminum alloy foams in mild steel tubes. The foam has been prepared by the melt route process with an addition of 5wt.% silicon carbide particles. The fabricated aluminum alloy foams were characterized by field emission scanning electron microscopy, x-ray diffraction, Fourier transform infrared spectroscopy, and Material Pro analyzer. It was observed that the foam-filled tubes could absorb more energy as compared to the unfilled tubes before reaching the complete densification point. Also, the aluminum alloy foams had better energy absorption capacity during the crash or impact loading. This article demonstrates the excellent ability of aluminum alloy foam application in the field where there is a need to absorb crash energy. It is to be noted that the amount of energy absorption will be greater for low-density foam filled in thin-wall rectangular section tubes. We have seen an increasing trend in the application of aluminum foams inside the thin-wall mild steel tubes for maximum energy absorption.
The dynamical symmetry limit of the two-fluid Interacting Vector Boson Model (IVBM), defined through the chain Sp(12,R) contains U(3,3) contains Up(3) x Un(3) contains SU*(3) contains SO(3), is considered and applied for the description of nuclear collective spectra exhibiting axially asymmetric features. The effect of the introduction of a Majorana interaction to the SU*(3) model Hamiltonian on the γ-band energies is studied. The theoretical predictions are compared with the experimental data for 192Os, 190Os, and 112Ru isotopes. It is shown that by taking into account the full symplectic structures in the considered dynamical symmetry of the IVBM, the proper description of the energy spectra and the γ-band energy staggering of the nuclei under considerations can be achieved. The obtained results show that the potential energy surfaces for the following two nuclei 192Os and 112Ru, possess almost γ-flat potentials with very shallow triaxial minima, suggesting a more complex and intermediate situation between γ-rigid and γ-unstable structures. Additionally, the absolute B(E2) intraband transition probabilities between the states of the ground-state band and γ band, as well as the B(M1) interband transition probabilities between the states of the ground and γ bands for the two nuclei 192Os and 190Os are calculated and compared with experiment and for the B(E2) values with the predictions of some other collective models incorporating the γ-rigid or γ-unstable structures. The obtained results agree well with the experimental data and reveal the relevance of the used dynamical symmetry of IVBM in the description of nuclei exhibiting axially asymmetric features in their spectra. (orig.)
Tri-axial Shape Coexistence and a New Aligned Band in 178Os
Govil, I. M.
2009-03-01
The Os nuclei lie in the beginning of the transitional region between the well deformed rare earth and spherical lead isotopes. The nuclei in this region are believed to be soft to changes in gamma deformation due to the softness of nuclear potential which may result in the shape coexistence. The neutron Fermi levels in Os nuclei from A = 170 to A = 186 lie in the middle of i13/2 orbital so that their shape in the ground state tends to take an appreciable prolate deformation. Hence collective bands with the well defined moment of inertia occur and the effect of different proton orbitals is observed as a modulation of the prolate structure. The anomalies in the yrast sequence, an effect attributed to change in moment of inertia of the ground state rotational band and the band crossing phenomena, are very important and vary strongly with neutron number in case of Os nuclei. The nuclear structure of 178Os nucleus has been studied using the reaction 165Ho (20Ne, p6n) 178Os. Indian National Gamma Array (INGA) consisting of six Clover detectors with anti Compton shields was used for the detection of resulting gamma rays. The Direction Correlation of γ-rays de-exciting Oriented states (DCO) ratio and polarization of gamma rays were measured to assign spin, parity and multipolarity of transitions. Twenty one new transitions belonging to the 178Os nucleus have been identified. The sudden and rather strong gain in aligned angular momentum is observed in the yrast band of 178Os. A new aligned rotational band similar to 180Os is also discovered in this nucleus. This band exhibits a very complex decay pattern with a single linking transition of 1778 keV to the ground state band. The tri-axial shape co-existence is also observed in this nucleus at higher excitation. The experimental results are compared with the Microscopic Hartree-Fock model calculations.
FINITE ELEMENT ANALYSIS OF AXIAL FEED BAR ROLLING
C.G. Xu; G.H. Liu; G.S. Ren; Z. Shen; C.P. Ma; W. W. Ren
2007-01-01
A flexible technique of hot working of bars by axial feed rolling was introduced. The processdeformation, strain field, stress field, and temperature field of the parts are analyzed by finite elementmethod (FEM)-simulation software DEFORM-3D. The material flow rule and tool load have beeninvestigated.
On renormalization of axial anomaly
It is shown that multiplicative renormalization of the axial singlet current results in renormalization of the axial anomaly in all orders of perturbation theory. It is a necessary condition for the Adler - Bardeen theorem being valid. 10 refs.; 2 figs
Axial compressor stability enhancement
Houghton, Timothy Oliver.
2010-01-01
Aircraft jet engines must operate in a stable manner at all times. One source of instability is compressor stall. Stall problems can be reduced by machining cavities into the compressor casing adjacent to the rotor blades. This ?casing treatment? is the focus of the present work. Two treatment configurations are tested: circumferential grooves cut into the casing above the rotor blades, and axial slots cut into the casing adjacent to the rotor blade leading edges. The performance of a single ...
Fragmentation of an axially impacted slender rod
Ji, W.; Waas, A. M.
2010-02-01
Motivated by experimental results on the dynamic buckling and fragmentation of a vertical column impacted by a falling mass, results from an analytical model for dynamic buckling which considers the dynamic interaction between the axial column deformation and the out-of-plane buckling displacements are used to interpret the fragmentation process and the resulting fragment lengths. It is shown that a critical time exists for the rod to undergo fragmentation. At this critical time, the rod deforms in a modulated pattern of waves, setting up the stage for the ensuing fragmentation as a result of induced large curvatures that exceed the critical bending strain of the rod material. The resulting fragment length distributions, which show two characteristics peaks at \\frac{\\lambda}{2} and \\frac{\\lambda}{4} , where λ is a characteristic half-wavelength, are found to compare favorably with the experimental results.
Niwa, Ken; Miyajima, Nobuyoshi; Seto, Yusuke; Ohgushi, Kenya; Gotou, Hirotada; Yagi, Takehiko
2012-03-01
The perovskite (Pv) to post-perovskite (PPv) phase transition and the deformation texture of the PPv phase were investigated on the basis of a high-pressure X-ray diffraction (XRD) study of CaIrO3 using a diamond-anvil cell in a pressure range up to 31 GPa. The development of a crystallographic preferred orientation (CPO) in the PPv phase was observed after the plastic deformation from 8 or 9 GPa to 31 GPa at both room and high (˜1500 K) temperatures. The observed CPOs in the present study indicate that the (0 1 0) plane worked as an active slip plane in the PPv phase over the entire pressure and temperature range of the present experiment. We also confirmed that the Pv to PPv phase transition proceeds at room temperature under high-stress conditions. The phase transition under high-stress condition is in stark contrast to the results of a previous hydrostatic experiment in which the Pv-CaIrO3 remained stable in a helium media at 31 GPa and room temperature. This indicates that shear stress plays an important role in the Pv to PPv phase transition, and this effect should be taken into account when the thermal structure at the D″ layer is discussed on the basis of the high-pressure experiments.
Walt Wells
2008-01-01
Full Text Available Our objective in this paper is to solve a second order differential equation for a long, simply supported column member subjected to a lateral axial load using Heun's numerical method. We will use the solution to find the critical load at which the column member will fail due to buckling. We will calculate this load using Euler's derived analytical approach for an exact solution, as well as Euler's Numerical Method. We will then compare the three calculated values to see how much they deviate from one another. During the critical load calculation, it will be necessary to calculate the moment of inertia for the column member.
Variable focal length deformable mirror
Headley, Daniel; Ramsey, Marc; Schwarz, Jens
2007-06-12
A variable focal length deformable mirror has an inner ring and an outer ring that simply support and push axially on opposite sides of a mirror plate. The resulting variable clamping force deforms the mirror plate to provide a parabolic mirror shape. The rings are parallel planar sections of a single paraboloid and can provide an on-axis focus, if the rings are circular, or an off-axis focus, if the rings are elliptical. The focal length of the deformable mirror can be varied by changing the variable clamping force. The deformable mirror can generally be used in any application requiring the focusing or defocusing of light, including with both coherent and incoherent light sources.
Deformation and fracture of Berea sandstone
Bernabe, Yves; Brace, W. F.
Samples of Berea sandstone were deformed to failure at different values of the confining pressure, Pc (from 10 to 250 MPa), and the pore pressure, Pp (from 0 to 130 MPa), at different strain rates and with pore fluids of different viscosities. Axial stress and strain were recorded in all tests. In addition, volumetric strain was measured in tests run at a strain rate of 2×10-5 s-1. The microstructure of several deformed samples was observed using the SEM. When the pore fluid was distilled water, the tests were performed in truly drained conditions at all strain rates. Results indicated that Pc and Pp had roughly opposite effects. With increasing Pc-Pp the samples showed a smooth transition from localized brittle fracture to uniformly distributed cataclastic flow. The data collected agreed well with a theoretical model in which strain localization is considered as an instability in the material constitutive relations. In Berea sandstone the stabilizing mechanism appeared to be the compaction caused by fragmentation of grains and the rearrangement of these fragments in the preexisting pore space. When the pore fluid was a highly viscous silicone fluid and the strain rate was 2×10-3 s-1, the sample behavior was not consistent with truly drained conditions. In the brittle regime a decrease in pore pressure within the sample due to dilation produced dilatancy-hardening. The samples deformed in the ductile regime, on the other hand, showed a loss of strength and signs of embrittlement. This weakening/embrittiement was caused by an increase in pore pressure within the sample due to compaction.
Axial-symmetrical domain structures in ferrite-garnet films
Applying the improved technique of double ultrahigh-speed photography one studied occurrence and progress of domain structure upon magnetization of a small section of (BiLaTm)3(FeGa)5O12 ferrite-garnet film prior to saturation. The radial deformation affecting the specimen on the magnetized coil side was determined to break single-axis anisotropy resulting in occurrence of axial-oriented band domain structure inside the magnetized range. That structure period reduced with growth of the pulse field amplitude. Band axial-oriented domain structure is formed under the effect of the magnetostatic axisymmetric field
Axial Deformation of Monolayer Graphene under Tension and Compression
Papagelis, K.; Frank, Otakar; Tsoukleri, G.; Parthenios, J.; Novoselov, K. S.; Galiotis, C.
Heidelberg: Springer, 2012 - (Ottaviano, L.; Morandi, V.), s. 87-97 ISBN 978-3-642-20643-6. [GraphITA 2011. L´Aquila (IT), 15.05.2011-18.05.2011] Institutional research plan: CEZ:AV0Z40400503 Keywords : monolayer graphene * Raman spectroscopy Subject RIV: CG - Electrochemistry
Axial skeletal CT densitometry
Since the discovery of the Roentgen ray a precise and accurate assessment of bone mineral content has been a challenge to many investigators. A number of methods have been developed but no one satisfied. Considering its technical possibilities computed tomography is very promising in determination of bone mineral content (BMC). The new modality enables BMC estimations in the axial skeletal trabecular bone. CT densitometry can be performed on a normal commercially available third generation whole body CT scanner. No dedicated device in a special clinical set-up is necessary. In this study 106 patients, most of them clinically suspected of osteoporosis, were examined. The new method CT densitometry has been evaluated. The results have been correlated to alternative BMC determination methods. (Auth.)
Mechanisms for spin suppression and orbital enhancement in M1 transitions: Critical assessment
We discuss different nuclear structure properties that may lead to spin suppression in magnetic dipole excitations (as well as in Gamow-Teller transitions). We especially compare the triaxial and the axial asymptotic deformation limits and show that the summed B(M1) strength can be quite different in the two cases. A connection between triaxial deformation and spin suppression is established. It is known, however, that modern Hartree-Fock calculations yield axially symmetric solutions for several nuclei which were previously thought to be triaxial. We show that taking into account the effects of higher shells can lead to an enhanced orbital contribution to M1 excitations without affecting ground-state magnetic moments
Large deformation dynamic bending of composite beams
Derian, Edward J.
1985-01-01
The large deformation response of composite beams subjected to a dynamic axial load was studied. The beams were loaded with a moderate amount of eccentricity to promote bending. The study was primarily experimental but some finite element results were obtained. Both the deformation and the failure of the beams were of interest. The static response of the beams was also studied in order to determine the difference between the static and dynamic failure. Twelve different la...
Axial anomaly in nonrenormalizable theories
The anomaly for the axial current in nonrenormalizable theories with electromagnetic coupling is considered. The spinor electrodynamics with Pauli term is examined in detail using the Feynman graph technique and the point-splitting method. The same finite value for the axial anomaly emerges. (author)
Shen, Yu; Ren, Zhongming; Li, Xi; Ren, Weili; Xi, Yan
2011-12-01
Effect of a low axial magnetic field on the growth behavior of the primary Al 2Cu phase in the Al-40 wt% Cu hypereutectic alloy during directional solidification at a low growth speed has been investigated experimentally. The results show that the application of a low magnetic field (≤1 T) causes the primary Al 2Cu phase to become deformed and irregular opposed to the well developed strip-like primary phase in the absence of the field. The deformation of the primary phase is maximum when a 0.5 T magnetic field is applied. Moreover, it has been found that the magnetic field promotes a transition of the primary phase morphology from faceted growth to irregular cellular structure and makes the primary phase spacing decrease with the increase of the magnetic field intensity. From the macroscopic scale, the magnetic field causes the occurrence of a considerable radial macrosegregation. These experimental results may be attributed to the effects of thermoelectric magnetic force (TEMF) in the solid and thermoelectromagnetic convection (TEMC) in the liquid. Further, the model of these effects is presented and evaluated numerically. The results indicate that the numerical magnitude of the TEMF during directional solidification under a 0.5 T low axial magnetic field can be of the order of 10 3 N/m 3. The force causes TEMC at different scales to modify the distribution of solute at the interface and should be responsible for the deformation, fracture and deflection of the primary phase.
Electric quadrupole transitions of the Bohr Hamiltonian with Manning-Rosen potential
Chabab, M; Lahbas, A; Oulne, M
2016-01-01
Analytical expressions of the wave functions are derived for a Bohr Hamiltonian with the Manning{Rosen potential in the cases of {\\gamma}-unstable nuclei and axially symmetric prolate deformed ones with {\\gamma}=0. By exploiting the results we have obtained in a recent work on the same theme Ref. [1], we have calculated the B(E2) transition rates for 34 {\\gamma}-unstable and 38 rotational nuclei and compared to experimental data, revealing a qualitative agreement with the experiment and phase transitions within the ground state band and showing also that the Manning-Rosen potential is more appropriate for such calculations than other potentials.
Rapalino, Otto; Smirniotopoulos, James G
2016-01-01
Extra-axial brain tumors are the most common adult intracranial neoplasms and encompass a broad spectrum of pathologic subtypes. Meningiomas are the most common extra-axial brain tumor (approximately one-third of all intracranial neoplasms) and typically present as slowly growing dural-based masses. Benign meningiomas are very common, and may occasionally be difficult to differentiate from more aggressive subtypes (i.e., atypical or malignant varieties) or other dural-based masses with more aggressive biologic behavior (e.g., hemangiopericytoma or dural-based metastases). Many neoplasms that typically affect the brain parenchyma (intra-axial), such as gliomas, may also present with primary or secondary extra-axial involvement. This chapter provides a general and concise overview of the common types of extra-axial tumors and their typical imaging features. PMID:27432671
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...
Build Axial Gradient Field by Using Axial Magnetized Permanent Rings
无
2002-01-01
Axial magnetic field produced by an axial magnetized permanent ring was studied. For two permanent rings, if they are magnetized in the same directions, a nearly uniform axial field can be produced. If they are magnetized in opposite direction,an axial gradient magnetic field can be generated, with the field range changing from -B0 to B0. A permanent magnet with a high axial gradient field was fabricated, the measured results agree with the PANDIRA calculation very well. For wider usage,it is desirable for the field gradient to be changed. Some methods to produce the variable gradient field are presented. These kinds of axial gradient magnetic field can also be used as a beam focusing for linear accelerator if the periodic field can be produced along the beam trajectory. The axial magnetic field is something like a solenoid, large stray field will leak to the outside environment if no method is taken to control them. In this paper, one method is illustrated to shield off the outside leakage field.
Notari, Alessio
2016-01-01
We analyze in detail the background cosmological evolution of a scalar field coupled to a massless abelian gauge field through an axial term $\\frac{\\phi}{f_\\gamma} F \\tilde{F}$, such as in the case of an axion. Gauge fields in this case are known to experience tachyonic growth and therefore can backreact on the background as an effective dissipation into radiation energy density $\\rho_R$, which which can lead to inflation without the need of a flat potential. We analyze the system, for momenta $k$ smaller than the cutoff $f_\\gamma$, including numerically the backreaction. We consider the evolution from a given static initial condition and explicitly show that, if $f_\\gamma$ is smaller than the field excursion $\\phi_0$ by about a factor of at least ${\\cal O} (20)$, there is a friction effect which turns on before that the field can fall down and which can then lead to a very long stage of inflation with a generic potential. In addition we find superimposed oscillations, which would get imprinted on any kind of...
Bode, Hans R.
2009-01-01
Morphogen gradients play an important role in pattern formation during early stages of embryonic development in many bilaterians. In an adult hydra, axial patterning processes are constantly active because of the tissue dynamics in the adult. These processes include an organizer region in the head, which continuously produces and transmits two signals that are distributed in gradients down the body column. One signal sets up and maintains the head activation gradient, which is a morphogenetic gradient. This gradient confers the capacity of head formation on tissue of the body column, which takes place during bud formation, hydra's mode of asexual reproduction, as well as during head regeneration following bisection of the animal anywhere along the body column. The other signal sets up the head inhibition gradient, which prevents head formation, thereby restricting bud formation to the lower part of the body column in an adult hydra. Little is known about the molecular basis of the two gradients. In contrast, the canonical Wnt pathway plays a central role in setting up and maintaining the head organizer. PMID:20066073
Hansen, N.; Huang, X.; Hughes, D.A.
2004-01-01
Microstructural characterization and modeling has shown that a variety of metals deformed by different thermomechanical processes follows a general path of grain subdivision, by dislocation boundaries and high angle boundaries. This subdivision has been observed to very small structural scales...
Deformation mechanisms in experimentally deformed Boom Clay
Desbois, Guillaume; Schuck, Bernhard; Urai, Janos
2016-04-01
Bulk mechanical and transport properties of reference claystones for deep disposal of radioactive waste have been investigated since many years but little is known about microscale deformation mechanisms because accessing the relevant microstructure in these soft, very fine-grained, low permeable and low porous materials remains difficult. Recent development of ion beam polishing methods to prepare high quality damage free surfaces for scanning electron microscope (SEM) is opening new fields of microstructural investigation in claystones towards a better understanding of the deformation behavior transitional between rocks and soils. We present results of Boom Clay deformed in a triaxial cell in a consolidated - undrained test at a confining pressure of 0.375 MPa (i.e. close to natural value), with σ1 perpendicular to the bedding. Experiments stopped at 20 % strain. As a first approximation, the plasticity of the sample can be described by a Mohr-Coulomb type failure envelope with a coefficient of cohesion C = 0.117 MPa and an internal friction angle ϕ = 18.7°. After deformation test, the bulk sample shows a shear zone at an angle of about 35° from the vertical with an offset of about 5 mm. We used the "Lamipeel" method that allows producing a permanent absolutely plane and large size etched micro relief-replica in order to localize and to document the shear zone at the scale of the deformed core. High-resolution imaging of microstructures was mostly done by using the BIB-SEM method on key-regions identified after the "Lamipeel" method. Detailed BIB-SEM investigations of shear zones show the following: the boundaries between the shear zone and the host rock are sharp, clay aggregates and clastic grains are strongly reoriented parallel to the shear direction, and the porosity is significantly reduced in the shear zone and the grain size is smaller in the shear zone than in the host rock but there is no evidence for broken grains. Comparison of microstructures
Role of cranking frequency in hot rotating deformed nuclei
A comparative study between the cranking method and Lagrangian Multiplier method of generating angular momentum reveals that the rotational frequency ω and Lagrangian Multiplier γ are identically equal for axially symmetric shapes, while for triaxially deformed nuclei γ ≠ ω. In this paper the role of the cranking frequency in hot rotating deformed nuclei is studied
Study of axial magnetic effect
The Axial Magnetic Effect manifests itself as an equilibrium energy flow of massless fermions induced by the axial (chiral) magnetic field. Here we study the Axial Magnetic Effect in the quenched SU(2) lattice gauge theory with massless overlap fermions at finite temperature. We numerically observe that in the low-temperature hadron phase the effect is absent due to the quark confinement. In the high-temperature deconfinement phase the energy flow is an increasing function of the temperature which reaches the predicted asymptotic T2 behavior at high temperatures. We find, however, that energy flow is about one order of magnitude lower compared to a theoretical prediction
Characterization of Multiflux Axial Compressors
In the present work the results of analytical models of performance are compared with experimental data acquired in the multi flux axial compressor test facility, built in The Pilcaniyeu Technological Complex for the SIGMA project.We describe the experimental circuit and the data of the dispersion inside the axial compressor obtained using a tracer gas through one of the annular inlets.The attained results can be used to validate the design code for the multi flux axial compressors and SIGMA industrial plant
Axial gap rotating electrical machine
None
2016-02-23
Direct drive rotating electrical machines with axial air gaps are disclosed. In these machines, a rotor ring and stator ring define an axial air gap between them. Sets of gap-maintaining rolling supports bear between the rotor ring and the stator ring at their peripheries to maintain the axial air gap. Also disclosed are wind turbines using these generators, and structures and methods for mounting direct drive rotating electrical generators to the hubs of wind turbines. In particular, the rotor ring of the generator may be carried directly by the hub of a wind turbine to rotate relative to a shaft without being mounted directly to the shaft.
Two samples of polycrystalline naturally deformed hexagonal Pyrrhotite were deformed experimentally in axial compression tests with different temperatures and strain. The texture of the naturally deformed ore was investigated both by X-ray and neutron texture analyses. Texture measurements on the experimentally deformed ore were carried out by neutron diffraction. (orig.)
Quadrupole Deformation of Barium Isotopes
Sugita, M; Furuno, K
1998-01-01
The B(E2:0_1^+ -> 2_1^+) values of the Ba isotopes (Z=56) exhibit a sharp increase in deformation as the neutron numbers approach the mid-shell value of N=66. This behavior is anomalous because the 2_1^+ level energies are very similar to those of the neighboring isotopes. By means of the axially-symmetric deformed Woods-Saxon (WS) hamiltonian plus the BCS method, we investigated the systematics of B(E2) of the Ba isotopes. We showed that 15% of the B(E2) values at N=66 was due to the level crossing, occurring at the deformation with beta being nearly 0.3, between the proton orbits originating from the orbits Omega=1/2^-(h11/2) and 9/2^+(g9/2) at zero deformation. The latter of these two was an intruder orbit originating from below the energy gap at Z=50, rising higher in energy with the deformation and intruding the Z=50-82 shell. These two orbits have the largest magnitude of the quadrupole moment with a different sign among the orbits near and below the Fermi surface. Occupancy and non-occupancy of these o...
Picazo, S. M.; Cannat, M.; Manatschal, G.
2012-12-01
The exhumation of mantle-derived rocks is widespread at slow and ultraslow Mid-Ocean Ridges and at the Ocean-Continent Transition (OCT) of rifted continental margins. It occurs along large offset normal faults also called detachment faults. Thermo-mechanical models indicate that significant strain softening of the fault rocks in the footwall is required in order to produce such large fault offsets. Our work focuses on actual deformation textures, and the associated mineralogy in ultramafic rocks sampled in the upper levels of the footwall next to the exhumation fault at two contrasted exhumation settings: the Mid-Atlantic Ridge (MAR) at lat. 13°N and 15°N (next to the Ashadze and Logatchev vent sites); and two OCT examples, the Totalp relict of a paleo-Tethys OCT exposed in SE Switzerland, and the Iberian distal margin (ODP Leg 173 Site 1070). These two settings differ by a number of characteristics, most notably the nature of the exhumed mantle (sub-continental mantle at OCTs, oceanic mantle at the ridge) and the extent of magmatic activity during exhumation (extensive magmatism at the MAR, few magmatic rocks at OCTs). Our comparative approach aims at identifying possible differences in the deformation processes during exhumation. We show that in both settings the ultramafic rocks in the upper levels of the footwall next to the detachment fault undergo a series of plastic to semi-brittle and brittle deformations. In samples from OCT settings, we find a cataclasites to gouges-sequence that affects the serpentinized peridotites. It involves a component of plastic deformation of serpentine following pronounced brittle grain-size reduction responsible for matrix-supported gouges formation in the most highly strained intervals. In this case the rheology of serpentine therefore controls the detachment fault. A similar sequence of serpentinite cataclasites and gouges is found in a few samples at one of the studied MAR locations, but in most samples from the MAR we find
Aiming to conduct a measurement under further higher resolution, a TOF measurement of the fission fragment of 235U(nth,f) was conducted by using a thin-film scintillator excellent in time responsibility. By TOF measurement, the fission fragment mass after emitting the prompt neutron and the numbers of the prompt neutron could be obtained. And, double energy measurement at the different incident proton energy was conducted for 238U(p,f) to investigate the to investigate the energy dependency of the nuclear fission. As a result of investigating the nuclear fission mechanism in multi face and due to the obtained data, it was found that degree of deformation of the fission fragment played an important role. However, as data on the prompt neutron numbers was not obtained this time, more detailed investigation could not be conducted. (G.K.)
Takamiya, Koichi; Inoue, Takakazu; Nakanishi, Kiyoshi [Osaka Univ., Toyonaka (Japan). Faculty of Science] [and others
1997-03-01
Aiming to conduct a measurement under further higher resolution, a TOF measurement of the fission fragment of {sup 235}U(n{sub th},f) was conducted by using a thin-film scintillator excellent in time responsibility. By TOF measurement, the fission fragment mass after emitting the prompt neutron and the numbers of the prompt neutron could be obtained. And, double energy measurement at the different incident proton energy was conducted for {sup 238}U(p,f) to investigate the to investigate the energy dependency of the nuclear fission. As a result of investigating the nuclear fission mechanism in multi face and due to the obtained data, it was found that degree of deformation of the fission fragment played an important role. However, as data on the prompt neutron numbers was not obtained this time, more detailed investigation could not be conducted. (G.K.)
Evaluation of various Deformable Image Registrations for Point and Volume Variations
Han, Su Chul; Park, Seungwoo; Lee, Soon Sung; Jung, Haijo; Kim, Mi-Sook; Yoo, Hyung Jun; Ji, Young Hoon; Yi, Chul Young; Kim, Kum Bae
2015-01-01
The accuracy of deformable image registration (DIR) has a significant dosimetric impact in radiation treatment planning. We evaluated accuracy of various DIR algorithms using variations of the deformation point and volume. The reference image (Iref) and volume (Vref) was first generated with virtual deformation QA software (ImSimQA, Oncology System Limited, UK). We deformed Iref with axial movement of deformation point and Vref depending on the types of deformation that are the deformation1 is to increase the Vref (relaxation) and the deformation 2 is to decrease . The deformed image (Idef) and volume (Vdef) acquired by ImSimQA software were inversely deformed to Iref and Vref using DIR algorithms. As a result, we acquired deformed image (Iid) from Idef and volume (Vid) from Vdef. The DIR algorithms were the Horn Schunk optical flow (HS), Iterative Optical Flow (IOF), Modified Demons (MD) and Fast Demons (FD) with the Deformable Image Registration and Adaptive Radiotherapy Toolkit (DIRART) of MATLAB. The imag...
Vectorial versus axial goldstone bosons
The Yukawa interactions of fermions with Goldstone bosons are given in closed form for an arbitrary renormalizable field theory to all orders of perturbation theory or for a general effective Lagrangian. Although the diagonal couplings are always pseudoscalar there is an important difference between spontaneously broken vector and axial-vector global symmetries. Compared to the axial case, the diagonal douplings of 'vectorial' Goldstone bosons to charged fermions are suppressed by mixing angles or appear only via radiative corrections involving gauge fields. This general result may be relevant for the problem of flavour symmetry breaking in composite models. (Author)
Simulation of an Axial Vircator
Tikhomirov, V V
2013-01-01
An algorithm of particle-in-cell simulations is described and tested to aid further the actual design of simple vircators working on axially symmetric modes. The methods of correction of the numerical solution, have been chosen and jointly tested, allow the stable simulation of the fast nonlinear multiflow dynamics of virtual cathode formation and evolution, as well as the fields generated by the virtual cathode. The selected combination of the correction methods can be straightforwardly generalized to the case of axially nonsymmetric modes, while the parameters of these correction methods can be widely used to improve an agreement between the simulation predictions and the experimental data.
Elastic vibrational approach to giant resonances of deformed nuclei
Isoscalar giant resonances of arbitrary multipolarity in deformed nuclei are studied with the help of the variational principle within the framework of the nuclear elastic vibration. A particular attention is given to the fragmentation of the giant monopole and quadrupole resonances. It is shown how the nuclear surface deformation contributes to the fragmentation through the coupling between the monopole and quadrupole modes of oscillation. Simple formulas for the giant resonance energies of deformed nuclei are obtained for both axial and non-axial deformations. Surface tension and Coulomb repulsion are included in the course of formulation but practical evaluations are made without them. Most numerical results are concerned with well-deformed nuclei such as those around A=150
Relativistic description of deformed nuclei
The author has shown that relativistic Hartree calculations using parameters that have been fit to the properties of nuclear matter can provide a good description of both spherical and axially deformed nuclei. The quantitative agreement with experiment is equivalent to that which was obtained in non-relativistic calculations using Skyrme interactions. The equilibrium deformation is strongly correlated with the size of the spin-orbit splitting, and that parameter sets which give roughly the correct value for this splitting provide the best agreement with the quadrupole moments in the s-d shell. Finally, for closed shell +/- 1 nuclei, it was shown that the self-consistent calculations are able to reproduce the experimental magnetic moments. This was not possible in relativistic calculations which include only the effects of the valence orbital
Axial structure of the nucleon
Veronique Bernard; Latifa Elouadrhiri; Ulf-G Meissner
2002-01-01
We review the current status of experimental and theoretical understanding of the axial nucleon structure at low and moderate energies. Topics considered include (quasi)elastic (anti)neutrino-nucleon scattering, charged pion electroproduction off nucleons and ordinary as well as radiative muon capture on the proton.
Rudigier, M; Dannhoff, M; Gerst, R-B; Jolie, J; Saed-Samii, N; Stegemann, S; Régis, J-M; Robledo, L M; Rodríguez-Guzmán, R; Blazhev, A; Fransen, Ch; Warr, N; Zell, K O
2015-01-01
The available data for E2 transition strengths in the region between neutron-deficient Hf and Pt isotopes are far from complete. More and precise data are needed to enhance the picture of structure evolution in this region and to test state-of-the-art nuclear models. In a simple model, the maximum collectivity is expected at the middle of the major shell. However, for actual nuclei, this picture may no longer be the case, and one should use a more realistic nuclear-structure model. We address this point by studying the spectroscopy of Hf. We remeasure the 2^+_1 half-lives of 172,174,176Hf, for which there is some disagreement in the literature. The main goal is to measure, for the first time, the half-lives of higher-lying states of the rotational band. The new results are compared to a theoretical calculation for absolute transition strengths. The half-lives were measured using \\gamma-\\gamma and conversion-electron-\\gamma delayed coincidences with the fast timing method. For the determination of half-lives i...
Morgan, Julia K.; McGovern, Patrick J.
2005-01-01
We have carried out two-dimensional particle dynamics simulations of granular piles subject to frictional Coulomb failure criteria to gain a first-order understanding of different modes of gravitational deformation within volcanoes. Under uniform basal and internal strength conditions, granular piles grow self-similarly, developing distinctive stratigraphies, morphologies, and structures. Piles constructed upon cohesive substrates exhibit particle avalanching, forming outward dipping strata and angle of repose slopes. Systematic decreases in basal strength lead to progressively deeper and steeper internal detachment faults and slip along a basal decollement; landslide forms grade from shallow slumps to deep-seated landslide and, finally, to axial subsidence and outward flank displacements, or volcanic spreading. Surface slopes decrease and develop concave up morphologies with decreasing decollement strength; depositional layers tilt progressively inward. Spatial variations in basal strength cause lateral transitions in pile structure, stratigraphy, and morphology. This approximation of volcanoes as Coulomb granular piles reproduces the richness of deformational structures and surface morphologies in many volcanic settings. The gentle slopes of Hawaiian volcanoes and Olympus Mons on Mars suggest weak basal decollements that enable volcanic spreading. High-angle normal faults, favored above weak decollements, are interpreted in both settings and may explain catastrophic sector collapse in Hawaii and broad aureole deposits surrounding Olympus Mons. In contrast, steeper slopes and shallow detachment faults predominate in the Canary Islands, thought to lack a weak decollement, favoring smaller, more frequent slope failures than predicted for Hawaii. The numerical results provide a useful predictive tool for interpreting dynamic behavior and associated geologic hazards of active volcanoes.
Axial compression physical testing of traditional and bird beak SHS T-joints
陈誉; 王江
2015-01-01
The static tests of nine traditional and bird beak square hollow structure (SHS) T-joints with differentβ values and connection types under axial compression at brace end were carried out. Experimental test schemes, failure modes of specimens, jack load−vertical displacement curves, jack load−deformation of chord and strain intensity distribution curves of joints were presented. The effects ofβ and connection types on axial compression property of joints were studied. The results show that the ultimate axial compression capacity of common bird beak SHS T-joints and diamond bird beak SHS T-joints is larger than that of traditional SHS T-joint specimens with big values ofβ. The ultimate axial compression capacity of diamond bird beak SHS T-joints is larger than that of common bird beak SHS T-joints. Asβ increases, the increase of the ultimate axial compression capacity of diamond bird beak SHS T-joints over that of common bird beak joints grows. The ultimate axial compression capacity and the initial axial stiffness of all kinds of joints increase asβincreases, and the initial axial stiffness of the diamond bird beak SHS T-joints is the largest. The ductilities of common bird beak and diamond bird beak SHS T-joints increase asβ increases, but the ductility of the traditional SHS T-joints decreases asβ increases.
Deformation induced martensitic transformation in stainless steels
Deformation induced martensitic transformation was investigated in metastable austenitic stainless steel. This steel can present a microstructure of austenite (γ), α' martensite and non magnetic ε martensite. Uni-axial tensile test was used for loading at different temperatures below room temperature (from -120 to 20 deg. C). During the deformation the transformation takes place at certain places in an anisotropic way and texture also develops. Quantitative phase analysis was done by X-ray diffraction (XRD) and magnetic methods while the texture was described by X-ray diffraction using a special inverse pole figure. The quantitative phase analysis has shown that the formation of α' and ε martensite from austenite is the function of deformation rate, and deformation temperature. The transformation of the textured austenite takes place in an anisotropic way and a well defined crystallographic relationship between the parent and α' martensite phase has been measured
Experimental investigation of the electromechanical phase transition in a dielectric elastomer tube
A membrane of dielectric elastomer undergoes a large deformation when it is subjected to a voltage through the thickness. Due to the attributes of light weight and high energy density, dielectric elastomers are suitable for electromechanical actuators and generators. In this work, the phenomenon of electromechanical phase transition is demonstrated experimentally in a tube of dielectric elastomer subjected to an internal pressure, an axial force and a voltage. When the voltage exceeds a critical value, the homogeneous deformation becomes unstable, and the tube deforms into coexistent states of bulged and unbulged sections. At the transition voltage the unbulged sections gradually bulge up and propagate. Two stable states are observed at the end of the phase transition process: one is coexistent states of the bulged and unbulged sections; the other is the wholly bulged tube. The achieved maximum voltage-induced deformation of the tube is 2200% in area, and the electromechanical energy conversion density is estimated to be 1.13 J g−1. These results are beyond the largest values reported in the literature. A theoretical analysis based on thermodynamics is carried out to qualitatively explain the observed experimental phenomenon. (paper)
Developing a Virtual Rock Deformation Laboratory
Zhu, W.; Ougier-simonin, A.; Lisabeth, H. P.; Banker, J. S.
2012-12-01
Experimental rock physics plays an important role in advancing earthquake research. Despite its importance in geophysics, reservoir engineering, waste deposits and energy resources, most geology departments in U.S. universities don't have rock deformation facilities. A virtual deformation laboratory can serve as an efficient tool to help geology students naturally and internationally learn about rock deformation. Working with computer science engineers, we built a virtual deformation laboratory that aims at fostering user interaction to facilitate classroom and outreach teaching and learning. The virtual lab is built to center around a triaxial deformation apparatus in which laboratory measurements of mechanical and transport properties such as stress, axial and radial strains, acoustic emission activities, wave velocities, and permeability are demonstrated. A student user can create her avatar to enter the virtual lab. In the virtual lab, the avatar can browse and choose among various rock samples, determine the testing conditions (pressure, temperature, strain rate, loading paths), then operate the virtual deformation machine to observe how deformation changes physical properties of rocks. Actual experimental results on the mechanical, frictional, sonic, acoustic and transport properties of different rocks at different conditions are compiled. The data acquisition system in the virtual lab is linked to the complied experimental data. Structural and microstructural images of deformed rocks are up-loaded and linked to different deformation tests. The integration of the microstructural image and the deformation data allows the student to visualize how forces reshape the structure of the rock and change the physical properties. The virtual lab is built using the Game Engine. The geological background, outstanding questions related to the geological environment, and physical and mechanical concepts associated with the problem will be illustrated on the web portal. In
A study of friction and axial effects in pellet-clad mechanical interaction
An analysis is made of the effect of friction and axial forces along the fuel rod in the pellet-cladding mechanical interaction in a commercial reactor under a power-up ramp. The effect of different pellet and rod shapes on their behaviour was also determined. A linear thermoelastic computer program was used in order to obtain the stiffness matrix of a compound structure from the stiffness of its components. Pellet-cladding displacements, localized deformations of the cladding in the interfaces between pellets, as well as pellet and cladding axial deformations were determined for different power axial profiles as well as for pellets with and without dishing and with height/diameter ratios of 1.7, 1 and 0.5. (M.E.L.)
Strong crystal size effect on deformation twinning
Yu, Qian; Shan, Zhi-Wei; Li, Ju;
2010-01-01
find that the stress required for deformation twinning increases drastically with decreasing sample size of a titanium alloy single crystal7, 8, until the sample size is reduced to one micrometre, below which the deformation twinning is entirely replaced by less correlated, ordinary dislocation...... plasticity. Accompanying the transition in deformation mechanism, the maximum flow stress of the submicrometre-sized pillars was observed to saturate at a value close to titanium’s ideal strength9, 10. We develop a ‘stimulated slip’ model to explain the strong size dependence of deformation twinning. The...
Axially symmetric rotating traversable wormholes
Kuhfittig, P K F
2003-01-01
This paper generalizes the static and spherically symmetric traversable wormhole geometry to a rotating axially symmetric one with a time-dependent angular velocity by means of an exact solution. It was found that the violation of the weak energy condition, although unavoidable, is considerably less severe than in the static spherically symmetric case. The radial tidal constraint is more easily met due to the rotation. Similar improvements are seen in one of the lateral tidal constraints. The magnitude of the angular velocity may have little effect on the weak energy condition violation for an axially symmetric wormhole. For a spherically symmetric one, however, the violation becomes less severe with increasing angular velocity. The time rate of change of the angular velocity, on the other hand, was found to have no effect at all. Finally, the angular velocity must depend only on the radial coordinate, confirming an earlier result.
View of the Axial Field Spectrometer
1980-01-01
The Axial Field Spectrometer, with the vertical uranium/scintillator calorimeter and the central drift chamber retracted for service. One coil of the Open Axial Field Magnet is just visible to the right.
Simulation of an Axial Vircator
Tikhomirov, V. V.; Siahlo, S. E.
2013-01-01
An algorithm of particle-in-cell simulations is described and tested to aid further the actual design of simple vircators working on axially symmetric modes. The methods of correction of the numerical solution, have been chosen and jointly tested, allow the stable simulation of the fast nonlinear multiflow dynamics of virtual cathode formation and evolution, as well as the fields generated by the virtual cathode. The selected combination of the correction methods can be straightforwardly gene...
Quantum fluctuations and stability of tetrahedral deformations in atomic nuclei
Zberecki, K; Magierski, P; Schunck, N
2006-01-01
The possible existence of stable axial octupole and tetrahedral deformations is investigated in $^{80}$Zr and $^{98}$Zr. HFBCS calculations with parity projection have been performed for various parametrizations of the Skyrme energy functional. The correlation and excitation energies of negative parity states associated with shape fluctuations have been obtained using the generator coordinate method (GCM). The results indicate that in these nuclei both the axial octupole and tetrahedral deformations are of dynamic character and possess similar characteristics. Various Skyrme forces give consistent results as a function of these two octupole degrees of freedom both at the mean-field level as well as for configuration mixing calculations.
Quantum fluctuations and stability of tetrahedral deformations in atomic nuclei
The possible existence of stable axial octupole and tetrahedral deformations is investigated in 80Zr and 98Zr. HFBCS calculations with parity projection have been performed for various parametrizations of the Skyrme energy functional. The correlation and excitation energies of negative parity states associated with shape fluctuations have been obtained using the generator coordinate method (GCM). The results indicate that in these nuclei both the axial octupole and tetrahedral deformations are of dynamic character and possess similar characteristics. Various Skyrme forces give consistent results as a function of these two octupole degrees of freedom both at the mean-field level as well as for configuration mixing calculations. (author)
Hot Quark Matter with an Axial Chemical Potential
Gatto, Raoul
2011-01-01
We analyze the phase diagram of hot quark matter in presence of an axial chemical potential, $\\mu_5$. The latter is introduced to mimic the chirality transitions induced, in hot Quantum Chromodynamics, by the strong sphaleron configurations. In particular, we study the curvature of the critical line at small $\\mu_5$, the effects of a finite quark mass and of a vector interaction. Moreover, we build the mixed phase at the first order phase transition line, and draw the phase diagram in the chiral density and temperature plane. We finally compute the full topological susceptibility in presence of a background of topological charge.
An exact dynamic stiffness matrix for axially loaded double-beam systems
Li Xiaobin; Xu Shuangxi; Wu Weiguo; Li Jun
2014-06-01
An exact dynamic stiffness method is presented in this paper to determine the natural frequencies and mode shapes of the axially loaded double-beam systems,which consist of two homogeneous and prismatic beams with a distributed spring in parallel between them.The effects of the axial force, shear deformation and rotary inertia are considered, as shown in the theoretical formulation. The dynamic stiffness influence coefficients are formulated from the governing differential equations of the axially loaded double-beam system in free vibration by using the Laplace transform method. An example is given to demonstrate the effectiveness of this method, in which ten boundary conditions are investigated and the effect of the axial force on the natural frequencies and mode shapes of the double-beam system are further discussed.
Operating limits for subassembly deformation in EBR-II
The deformation of a subassembly in response to the core environment is frequently the life limiting factor for that component in an LMFBR. Deformation can occur as diametral and axial growth or bowing of the subassembly. Such deformation has caused several handling problems in both the core and the storage basket of EBR-II and may also have contributed to reactivity anomalies during reactor operation. These problems generally affect plant availability but the reactivity anomalies could lead to a potential safety hazard. Because of these effects the deformation mechanisms must be understood and modeled. Diametral and axial growth of subassembly ducts in EBR-II is due to swelling and creep and is a function of temperature, neutron fluence and stress. The source of stress in a duct is the hydraulic pressure difference across the wall. By coupling the calculated subassembly growth rate to the available clearance in the core or storage basket a limiting neutron fluence, or exposure, can be established
Axial Force at the Vessel Bottom Induced by Axial Impellers
I. Fořt; P. Hasal; A. Paglianti; F. Magelli
2008-01-01
This paper deals with the axial force affecting the flat bottom of a cylindrical stirred vessel. The vessel is equipped with four radial baffles and is stirred with a four 45° pitched blade impeller pumping downwards. The set of pressure transducers is located along the whole radius of the flat bottom between two radial baffles. The radial distribution of the dynamic pressures indicated by the transducers is measured in dependence on the impeller off-bottom clearance and impeller speed.It fol...
Prediction of Axial and Radial Creep in CANDU 6 Pressure Tubes
Status and proposals: 1. A review of literature concerning on the in-reactor deformation of PTs has been carried ouţ. 2. A model based on MFNN has been proposed to assess the radial and axial creep of CANDU 6 PTs. 3. Preliminary discussion with Cernavoda NPP (Romania) has been lunched, and now the preparation of official documents (collaboration in providing the inspection data from fuel channel in Unit 1 and 2) are in progress. 4. Further activities: • Improvement MFNN to accommodate complex data base (eventually with many variables) for radial and axial in-reactor deformation PT, and to satisfy the requirements from NPP Cernavoda and hopefully from present CRP database; • To build-up a database by running the creep equations (if the creep constants are provided by AECL); training of MFNN on them and to qualify it as a tool for PT in-reactor deformation prediction
Skyrme RPA for spherical and axially symmetric nuclei
Repko, Anton; Nesterenko, V O; Reinhard, P -G
2015-01-01
Random Phase Approximation (RPA) is the basic method for calculation of excited states of nuclei over the Hartree-Fock ground state, suitable also for energy density functionals (EDF or DFT). We developed a convenient formalism for expressing densities and currents in a form of reduced matrix elements, which allows fast calculation of spectra for spherical nuclei. All terms of Skyrme functional were taken into account, so it is possible to calculate electric, magnetic and vortical/toroidal/compression transitions and strength functions of any multipolarity. Time-odd (spin) terms in Skyrme functional become important for magnetic M1 and isovector toroidal E1 transitions. It was also found that transition currents in pygmy region (low-lying part of E1 resonance) exhibit isoscalar toroidal flow, so the previously assumed picture of neutron-skin vibration is not the only mechanism present in pygmy transitions. RPA calculations with heavy axially-symmetric nuclei now become feasible on ordinary PC. Detailed formul...
The strange axial-vector mesons K1 (1270) and K1 (1400) are reanalyzed in the light of the updated experimental information and compared with the recent result on the Kππ production in τ decay. The mixing angle between the strange mesons of 3P1 and 1P1 is determined by the partial decay rates, and, independently, by the masses. They lead to θK∼33 degree or 57 degree. The observed K1 (1400) production dominance in the τ decay favors θK∼33 degree. Flavor-SU(3) breaking of 20% or so in the production amplitudes can explain quantitatively the observed production ratio
PWR AXIAL BURNUP PROFILE ANALYSIS
The purpose of this activity is to develop a representative ''limiting'' axial burnup profile for pressurized water reactors (PWRs), which would encompass the isotopic axial variations caused by different assembly irradiation histories, and produce conservative isotopics with respect to criticality. The effect that the low burnup regions near the ends of spent fuel have on system reactivity is termed the ''end-effect''. This calculation will quantify the end-effects associated with Pressurized Water Reactor (PWR) fuel assemblies emplaced in a hypothetical 21 PWR waste package. The scope of this calculation covers an initial enrichment range of 3.0 through 5.0 wt% U-235 and a burnup range of 10 through 50 GWd/MTU. This activity supports the validation of the process for ensuring conservative generation of spent fuel isotopics with respect to criticality safety applications, and the use of burnup credit for commercial spent nuclear fuel. The intended use of these results will be in the development of PWR waste package loading curves, and applications involving burnup credit. Limitations of this evaluation are that the limiting profiles are only confirmed for use with the B andW 15 x 15 fuel assembly design. However, this assembly design is considered bounding of all other typical commercial PWR fuel assembly designs. This calculation is subject to the Quality Assurance Requirements and Description (QARD) because this activity supports investigations of items or barriers on the Q-list (YMP 2001)
PWR AXIAL BURNUP PROFILE ANALYSIS
J.M. Acaglione
2003-09-17
The purpose of this activity is to develop a representative ''limiting'' axial burnup profile for pressurized water reactors (PWRs), which would encompass the isotopic axial variations caused by different assembly irradiation histories, and produce conservative isotopics with respect to criticality. The effect that the low burnup regions near the ends of spent fuel have on system reactivity is termed the ''end-effect''. This calculation will quantify the end-effects associated with Pressurized Water Reactor (PWR) fuel assemblies emplaced in a hypothetical 21 PWR waste package. The scope of this calculation covers an initial enrichment range of 3.0 through 5.0 wt% U-235 and a burnup range of 10 through 50 GWd/MTU. This activity supports the validation of the process for ensuring conservative generation of spent fuel isotopics with respect to criticality safety applications, and the use of burnup credit for commercial spent nuclear fuel. The intended use of these results will be in the development of PWR waste package loading curves, and applications involving burnup credit. Limitations of this evaluation are that the limiting profiles are only confirmed for use with the B&W 15 x 15 fuel assembly design. However, this assembly design is considered bounding of all other typical commercial PWR fuel assembly designs. This calculation is subject to the Quality Assurance Requirements and Description (QARD) because this activity supports investigations of items or barriers on the Q-list (YMP 2001).
李世荣; 万泽青; 张静华
2014-01-01
The free vibration of functionally graded material (FGM) beams is studied based on both the classical and the first-order shear deformation beam theories. The equations of motion for the FGM beams are derived by considering the shear deforma-tion and the axial, transversal, rotational, and axial-rotational coupling inertia forces on the assumption that the material properties vary arbitrarily in the thickness direction. By using the numerical shooting method to solve the eigenvalue problem of the coupled ordinary differential equations with different boundary conditions, the natural frequen-cies of the FGM Timoshenko beams are obtained numerically. In a special case of the classical beam theory, a proportional transformation between the natural frequencies of the FGM and the reference homogenous beams is obtained by using the mathematical similarity between the mathematical formulations. This formula provides a simple and useful approach to evaluate the natural frequencies of the FGM beams without dealing with the tension-bending coupling problem. Approximately, this analogous transition can also be extended to predict the frequencies of the FGM Timoshenko beams. The numerical results obtained by the shooting method and those obtained by the analogous transformation are presented to show the effects of the material gradient, the slenderness ratio, and the boundary conditions on the natural frequencies in detail.
Purpose: The accuracy of deformable image registration (DIR) has a significant dosimetric impact in radiation treatment planning. We evaluated accuracy of various DIR algorithms using virtual deformation QA software (ImSimQA, Oncology System Limited, UK). Methods: The reference image (Iref) and volume (Vref) was first generated with IMSIMQA software. We deformed Iref with axial movement of deformation point and Vref depending on the type of deformation that are the deformation1 is to increase the Vref (relaxation) and the deformation 2 is to decrease the Vref (contraction) .The deformed image (Idef) and volume (Vdef) were inversely deformed to Iref and Vref using DIR algorithms. As a Result, we acquired deformed image (Iid) and volume (Vid). The DIR algorithms were optical flow (HS, IOF) and demons (MD, FD) of the DIRART. The image similarity evaluation between Iref and Iid was calculated by Normalized Mutual Information (NMI) and Normalized Cross Correlation (NCC). The value of Dice Similarity Coefficient (DSC) was used for evaluation of volume similarity. Results: When moving distance of deformation point was 4 mm, the value of NMI was above 1.81 and NCC was above 0.99 in all DIR algorithms. Since the degree of deformation was increased, the degree of image similarity was decreased. When the Vref increased or decreased about 12%, the difference between Vref and Vid was within ±5% regardless of the type of deformation. The value of DSC was above 0.95 in deformation1 except for the MD algorithm. In case of deformation 2, that of DSC was above 0.95 in all DIR algorithms. Conclusion: The Idef and Vdef have not been completely restored to Iref and Vref and the accuracy of DIR algorithms was different depending on the degree of deformation. Hence, the performance of DIR algorithms should be verified for the desired applications
Han, S; Kim, K; Kim, M; Jung, H; Ji, Y [University of Science and Technology, Daejeon (Korea, Republic of); Korea institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Choi, S; Park, S [Korea institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)
2015-06-15
Purpose: The accuracy of deformable image registration (DIR) has a significant dosimetric impact in radiation treatment planning. We evaluated accuracy of various DIR algorithms using virtual deformation QA software (ImSimQA, Oncology System Limited, UK). Methods: The reference image (Iref) and volume (Vref) was first generated with IMSIMQA software. We deformed Iref with axial movement of deformation point and Vref depending on the type of deformation that are the deformation1 is to increase the Vref (relaxation) and the deformation 2 is to decrease the Vref (contraction) .The deformed image (Idef) and volume (Vdef) were inversely deformed to Iref and Vref using DIR algorithms. As a Result, we acquired deformed image (Iid) and volume (Vid). The DIR algorithms were optical flow (HS, IOF) and demons (MD, FD) of the DIRART. The image similarity evaluation between Iref and Iid was calculated by Normalized Mutual Information (NMI) and Normalized Cross Correlation (NCC). The value of Dice Similarity Coefficient (DSC) was used for evaluation of volume similarity. Results: When moving distance of deformation point was 4 mm, the value of NMI was above 1.81 and NCC was above 0.99 in all DIR algorithms. Since the degree of deformation was increased, the degree of image similarity was decreased. When the Vref increased or decreased about 12%, the difference between Vref and Vid was within ±5% regardless of the type of deformation. The value of DSC was above 0.95 in deformation1 except for the MD algorithm. In case of deformation 2, that of DSC was above 0.95 in all DIR algorithms. Conclusion: The Idef and Vdef have not been completely restored to Iref and Vref and the accuracy of DIR algorithms was different depending on the degree of deformation. Hence, the performance of DIR algorithms should be verified for the desired applications.
Classical studies of the ellipsoidal shapes for dynamical deformation theories of the nucleus
The shape-dependent functions of the Liquid Drop and the Droplet Models are analytically calculated for an ellipsoid. Using the ellipsoidal symmetries, these functions (including the curvature function) are written in terms of three basic expressions. The nuclear deformation energy can be calculated in a simple way for axially symmetric and asymmetric ellipsoidal nuclei whatever the magnitude of the deformation is
Mass Effect on Axial Charge Dynamics
Guo, Er-dong
2016-01-01
We studied effect of finite quark mass on the dynamics of axial charge using the D3/D7 model in holography. The mass term in axial anomaly equation affects both the fluctuation (generation) and dissipation of axial charge. We studied the dependence of the effect on quark mass and external magnetic field. For axial charge generation, we calculated the mass diffusion rate, which characterizes the helicity flipping rate. The rate is a non-monotonous function of mass and can be significantly enhanced by the magnetic field. The diffusive behavior is also related to a divergent susceptibility of axial charge. For axial charge dissipation, we found that in the long time limit, the mass term dissipates all the charge effectively generated by parallel electric and magnetic fields. The result is consistent with a relaxation time approximation. The rate of dissipation through mass term is a monotonous increasing function of both quark mass and magnetic field.
Axial Vector $Z'$ and Anomaly Cancellation
Ismail, Ahmed; Tsao, Kuo-Hsing; Unwin, James
2016-01-01
Whilst the prospect of new $Z'$ gauge bosons with only axial couplings to the Standard Model (SM) fermions is widely discussed, examples of anomaly-free renormalisable models are lacking in the literature. We look to remedy this by constructing several motivated examples. Specifically, we consider axial vectors which couple universally to all SM fermions, as well as those which are generation-specific, leptophilic, and leptophobic. Anomaly cancellation typically requires the presence of new coloured and charged chiral fermions, and we argue that the masses of these new states must generally be comparable to that of the axial vector. Finally, an axial vector mediator could provide a portal between SM and hidden sector states, and we also consider the possibility that the axial vector couples to dark matter. If the dark matter relic density is set due to freeze-out via the axial vector, this strongly constrains the parameter space.
An Assessment of Cumulative Axial and Torsional Fatigue in a Cobalt-Base Superalloy
Kalluri, Sreeramesh; Bonacuse, Peter J.
2010-01-01
Cumulative fatigue under axial and torsional loading conditions can include both load-order (higMow and low/high) as well as load-type sequence (axial/torsional and torsional/axial) effects. Previously reported experimental studies on a cobalt-base superalloy, Haynes 188 at 538 C, addressed these effects. These studies characterized the cumulative axial and torsional fatigue behavior under high amplitude followed by low amplitude (Kalluri, S. and Bonacuse, P. J., "Cumulative Axial and Torsional Fatigue: An Investigation of Load-Type Sequance Effects," in Multiaxial Fatigue and Deformation: Testing and Prediction, ASTM STP 1387, S. Kalluri, and P. J. Bonacuse, Eds., American Society for Testing and Materials, West Conshohocken, PA, 2000, pp. 281-301) and low amplitude followed by high amplitude (Bonacuse, P. and Kalluri, S. "Sequenced Axial and Torsional Cumulative Fatigue: Low Amplitude Followed by High Amplitude Loading," Biaxial/Multiaxial Fatigue and Fracture, ESIS Publication 31, A. Carpinteri, M. De Freitas, and A. Spagnoli, Eds., Elsevier, New York, 2003, pp. 165-182) conditions. In both studies, experiments with the following four load-type sequences were performed: (a) axial/axial, (b) torsional/torsional, (c) axial/torsional, and (d) torsional/axial. In this paper, the cumulative axial and torsional fatigue data generated in the two previous studies are combined to generate a comprehensive cumulative fatigue database on both the load-order and load-type sequence effects. This comprehensive database is used to examine applicability of the Palmgren-langer-Miner linear damage rule and a nonlinear damage curve approach for Haynes 188 subjected to the load-order and load-type sequencing described above. Summations of life fractions from the experiments are compared to the predictions from both the linear and nonlinear cumulative fatigue damage approaches. The significance of load-order versus load-type sequence effects for axial and torsional loading conditions
Axial velocity in decaying swirl flow
Algifri, A. H.; Bhardwaj, R. K.; Rao, Y. V. N.
1988-09-01
Experiments were carried out on turbulent swirling flow with variable initial swirl at different flow rates to study the effect of swirl on axial velocity. A correlation was made between the defect in the swirling flow axial velocity and the swirl number which locally defines the swirl intensity. An expression which can be used to predict the axial velocity distribution of turbulent swirling flow in a pipe is presented.
Sensorless Control of Axial Magnetic Bearings
Atsumo, Daichi; Yoshida, Toshiya; Ohniwa, Katsumi
This paper describes a sensorless control method of axial active magnetic bearings (AMBs). At high frequencies, inductance of the axial electromagnets is hardly dependent on the airgap because of the eddy current effects of the non-laminated core. Therefore the carrier frequency should be 3 kHz below to improve the sensitivity to the airgap. In the experiment, Sensorless controll of the axial AMBs have been achieved.
Single Crystal Deformation Experiments for Validation of Dislocation Dynamics Simulations
Lassila, D H; LeBlanc, M M; Rhee, M
2003-11-04
A new experimental apparatus has been developed for performing compression deformation experiments on high-purity Mo single crystals. These experiments provide data that can validate 3-D dislocation dynamics (DD) simulations. The experiments are performed under conditions that allow unconstrained deformation; thus, a relatively uniform state of axial stress is maintained during deformation. In the following sections, we describe the new experimental apparatus and our results from experiments performed at ambient temperature at a strain rate of s{sup -1}. Validation criteria based on the Mo experiments may include comparing the stress-strain response using 3-D strain information, the predicted slip-system yield, and work-hardening behavior.
Effective quantum number for axially symmetric problems
Trunov, N. N.
2014-01-01
We generalize the universal effective quantum number introduced earlier for centrally symmetric problems. The proposed number determines the semiclassical quantization condition for axially symmetric potentials.
Origin of axial current in scyllac
The origin of the axial current observed in Scyllac (a high beta stellarator experiment) is discussed. A shaped coil and/or helical winding produce rotational transform which links magnetic lines of force to the plasma column and the axial current is induced electromagnetically. This phenomenon is inherent in a pulsed high-beta stellarator. The rotational transform produced by the induced axial current is much smaller than that associated with the l = 1, 0 equilibrium fields. The effect of the axial current on the equilibrium and stability of the plasma column is thus small. It is also shown that the magnetic field shear near a plasma surface is very strong
Soft deformable self-propelled particles
Menzel, Andreas M.; Ohta, Takao
2012-01-01
In this work we investigate the collective behavior of self-propelled particles that deform due to local pairwise interactions. We demonstrate that this deformation alone can induce alignment of the velocity vectors. The onset of collective motion is analyzed. Applying a Gaussian-core repulsion between the particles, we find a transition to disordered non-collective motion under compression. We here explain that this reflects the reentrant fluid behavior of the general Gaussian-core model now...
Service stresses in expansion transitions of heat-exchanger U-tube joints
The purpose of this paper is to present and discuss the results of stress analyses within the expansion transition zones including the local discontinuity and transition geometry effects mainly from the operating stress point of view. The local stress calculations were simplified by assuming axisymmetric loads and axisymmetric geometry; these stresses were superimposed on the non-axisymmetric bending stresses due to the overall (global) structural deformations resulting in peak stress values. The local stress evaluation consisted of elasto-static, thermal-structural analysis using finite elements; four models were analyzed to examine the effects of (a) proximity of transition zone relative to the top of the tubesheet and (b) the profile of transition zone itself (including thickness variations). Pressure and thermal conditions included (a) hot leg and cold leg, (b) fouled and clean surfaces, and (c) sludge-pile effect. The local stresses are mainly of the wall bending type with comparable magnitudes in both the hoop and the axial directions and with steep gradients in axial as well as through-wall directions. Generally, the secondary side stress magnitudes were found to be higher than on the primary side. The tube-to-tubesheet discontinuity effect was found to dominate the resultant stresses more than either the effect of zone profile or zone location (from the point of view of operating loads). Significance of these factors and the resultant stresses are briefly discussed in relation to the local corrosion failures of the tubes. (orig.)
Roccaz, J
2006-07-15
The atomic nucleus can adopt a very elongated shape with an axis ratio 2:1, this is the superdeformation phenomenon. Nowadays more than 300 superdeformed bands have been identified at high spin, but the determination of excitation energies, spins and parities of the associated states have been established for only one tenth of these bands. The former quantities (E{sup *}, I, {pi}) can only be determined via the linking gamma-transitions between the superdeformed (sd) and the normally deformed (nd) states. Within the framework of this thesis, we have investigated the Hg{sup 192} nucleus in order to establish E{sup *}, I and {pi}. This nucleus is predicted to be doubly magic at superdeformation and hence is taken as a reference in the mass {approx} 190 region. The experiment was carried out at Strasbourg using the Euroball-IV array and the vivitron accelerator. The obtained results are not convincing and seem to be at the limit of the performances of Euroball. Next generation of arrays will abandon the Compton-shields and use tracking concept to reconstruct the trajectories of incident photons, and therefore we expect a huge increase of efficiency. The second part of this work was focused on the research and development work for the AGATA (Advanced GAmma Tracking Array) project. We have performed simulations with the GEANT-4 code and developed tracking methods to reconstruct pair-creation events. The full AGATA will be operational around 2015 and will enhance by around two orders of magnitude the observational limits. (author)
Axial range of conjugate adaptive optics in two-photon microscopy
Paudel, Hari P; Mertz, Jerome; Bifano, Thomas
2015-01-01
We describe an adaptive optics technique for two-photon microscopy in which the deformable mirror used for aberration compensation is positioned in a plane conjugate to the plane of the aberration. We demonstrate in a proof-of-principle experiment that this technique yields a large field of view advantage in comparison to standard pupil-conjugate adaptive optics. Further, we show that the extended field of view in conjugate AO is maintained over a relatively large axial translation of the deformable mirror with respect to the conjugate plane. We conclude with a discussion of limitations and prospects for the conjugate AO technique in two-photon biological microscopy.
Shimada, Mitsuhiro; Watanabe, Shin; Tagami, Shingo; Matsumoto, Takuma; Shimizu, Yoshifumi R.; Yahiro, Masanobu
2016-06-01
We perform simultaneous analysis of (1) matter radii, (2) B (E 2 ;0+→2+) transition probabilities, and (3) excitation energies, E (2+) and E (4+) , for Mg-4024 by using the beyond-mean-field (BMF) framework with angular-momentum-projected configuration mixing with respect to the axially symmetric β2 deformation with infinitesimal cranking. The BMF calculations successfully reproduce all of the data for rm,B (E 2 ) , and E (2+) and E (4+) , indicating that it is quite useful for data analysis; particularly for low-lying states. We also discuss the absolute value of the deformation parameter β2 deduced from measured values of B (E 2 ) and rm. This framework makes it possible to investigate the effects of β2 deformation, the change in β2 due to restoration of rotational symmetry, β2 configuration mixing, and the inclusion of time-odd components by infinitesimal cranking. Under the assumption of axial deformation and parity conservation, we clarify which effect is important for each of the three measurements and propose the kinds of BMF calculations that are practical for each of the three kinds of observables.
Shimada, Mitsuhiro; Tagami, Shingo; Matsumoto, Takuma; Shimizu, Yoshifumi R; Yahiro, Masanobu
2016-01-01
We perform simultaneous analysis of (1) matter radii, (2) $B(E2; 0^+ \\rightarrow 2^+ )$ transition probabilities, and (3) excitation energies, $E(2^+)$ and $E(4^+)$, for $^{24-40}$Mg by using the beyond mean-field (BMF) framework with angular-momentum-projected configuration mixing with respect to the axially symmetric $\\beta_2$ deformation with infinitesimal cranking. The BMF calculations successfully reproduce all of the data for $r_{\\rm m}$, $B(E2)$, and $E(2^+)$ and $E(4^+)$, indicating that it is quite useful for data analysis, particularly for low-lying states. We also discuss the absolute value of the deformation parameter $\\beta_2$ deduced from measured values of $B(E2)$ and $r_{\\rm m}$. This framework makes it possible to investigate the effects of $\\beta_2$ deformation, the change in $\\beta_2$ due to restoration of rotational symmetry, $\\beta_2$ configuration mixing, and the inclusion of time-odd components by infinitesimal cranking. Under the assumption of axial deformation and parity conservation,...
Polyakov, P. I.; Kucherenko, S. S.
2004-07-01
The paper deals with a generalizing analysis of elastically deforming regularities by examining the experimental results for magnetic semiconductors and dielectrics. The role of anisotropically deforming elastic (EAD) stresses, determined from the influence of temperature ( T), magnetic field ( H) and hydrostatic pressure ( P), in the formation and changes of the structural phase transitions (PTs) and properties has been estimated. From the analysis of investigations of the resistive and magnetostrictive properties and of PTs in La 0.7Ca 0.3MnO 3, LaMnO 3 the role of EAD in baro-, magneto-, and baromagnetoresistive effects has been determined and it has been deduced that their maximum temperature TPP is equal to the temperature of metal-semiconductor PT Tms. It is noted that the action of EAD stresses in the "cooling", "heating" effects of Tms( H), Tms( P) and Hg( T) change, and in T- H- P (5.1 K-2.42 kOe-1 kbar) influence on the resistive properties, and T- H (5.2 K-2.5 kOe) influence on the magnetostrictive properties is regular. Changes in properties, PT, and T- H- P-induced effects were found to be of the alternating-sign character. From the results of studies of the resonance properties and PTs in CuCl 2·2H 2O the role of EAD stresses has been determined and a correspondence in the T- H- P (1 K-4 kOe-3 kbar) effect on PT change has been revealed. Thermomagnetic and thermobaromagnetic effects have been revealed with the peaks corresponding to TPP=0 K, the temperature which coincides with that of the structural PT TST. The regularities in "cooling" and "heating" effects of H and P influence have been grounded, as well as those in TP( H), TP( H, P) change going on with sign alternation. The location of point P( HP, TP), where elastic and magnetoelastic anisotropies become conformable to each other at TP=9.2 K, has been found. It considerably differs from the known TN=4.3 K. The results of magnetization and of the field-temperature and field
Dávila, A.; Márquez, S.; Landgrave, E.; Vázquez, Z.; Vera, K.; Caudillo, C.
2015-06-01
A computerized system for real-time displacement visualization using carrier fringes in an electronic speckle in-plane sensitive interferometer allows force calibration for micro-displacement analysis of rat bones and verification of axial loading conditions. Once the force has been calibrated and the load is applied along the bone axis, the difference-of-phase method is used to obtain the phase map, which after phase unwrapping, allows the evaluation of the displacements produced by the bone deformation. The proposed method avoids common loading mistakes using first carrier fringes to assure that the loads are within the measuring capabilities of the in-plane interferometer and the Carré phase-stepping method to compensate for linear phase step miscalibration. The experimental results obtained with the calibration of loading forces and axial loading verification show the advantages of the system proposed here over a system which uses a cantilever configuration to make a similar bone deformation analysis.
Survey of Reflection-Asymmetric Nuclear Deformations
Olsen, Erik; Birge, Noah; Erler, Jochen; Nazarewicz, Witek; Perhac, Alex; Schunck, Nicolas; Stoitsov, Mario; Nuclei Collaboration
2015-10-01
Due to spontaneous symmetry breaking it is possible for a nucleus to have a deformed shape in its ground state. It is theorized that atoms whose nuclei have reflection-asymmetric or pear-like deformations could have non-zero electric dipole moments (EDMs). Such a trait would be evidence of CP-violation, a feature that goes beyond the Standard Model of Physics. It is the purpose of this project to predict which nuclei exhibit a reflection-asymmetric deformation and which of those would be the best candidates for an EDM measuring experiment. Using nuclear Density Functional Theory along with the new computer code AxialHFB and massively parallel computing we calculated ground state nuclear properties for thousands of even-even nuclei across the nuclear chart: from light to superheavy and from stable to short-lived systems. Six different Energy Density Functionals (EDFs) were used to assess systematic errors in our calculations. Overall, 140 even-even nuclei (near and among the lantanides and actinides and in the superheavy region near N = 184) were predicted by all 6 EDFs to have a pear-like deformation. The case of 112Xe also proved curious as it was predicted by 5 EDFs to have a pear-like deformation despite its proximity to the two-proton drip line. Deceased.
Collective models for quadrupole and octupole degrees of freedom and complex nuclear deformations
We review current advances in the theoretical study of nuclear quadrupole and octupole collectivity and complex shape deformations. We present a collective model formalism which consistently describes the strong parity shift effect observed in low-lying spectra of nuclei with octupole deformations together with the fine rotational band structure developed at higher angular momenta. The parity effect is obtained by the Schroedinger equation for oscillations of the reflection asymmetric (octupole) shape between two opposite orientations in an angular momentum dependent double-well potential. The rotational structure is obtained by the collective quadrupole-octupole rotation Hamiltonian (QORM). The unified model scheme reproduces the complicated beat staggering patterns observed in the octupole bands of light actinide nuclei. It explains the angular momentum evolution of octupole spectra as the interplay between the octupole shape oscillation (parity shift) mode and the stable quadrupole-octupole rotation mode. We also discuss an analytic collective model in which the relative presence of the quadrupole and octupole deformations is determined by a parameter (ψ0), while axial symmetry is obeyed. The model, called the Analytic Quadrupole Octupole Axially Symmetric model (AQOA), involves an infinite well potential, provides predictions for energy and B(EL) ratios which depend only on (ψ0), draws the border between the regions of octupole deformation and octupole vibrations in an essentially parameter-independent way, and describes well 226Th and 226Ra, for which experimental energy data are shown to suggest that they lie close to this border. The similarity of the AQOA results with ψ0=450 for ground state band spectra and B(E2) transition rates to the predictions of the X(5) model is pointed out. Analytic solutions are also obtained for Davidson potentials of the form β2+β4/β2, leading to the AQOA spectrum through a variational procedure. Also, we present results
Clinical observation of micro-coaxial phacoemulsification for axial high myopia with cataract
Rui-Fan Zhang
2014-11-01
Full Text Available AIM: To observe the clinical effect of micro-coaxial phacoemulsification combined with intraocular lens implantation in axial high myopia with cataract.METHODS: Fifty-three patients(74 eyeswith axial high myopia and cataract underwent micro-coaxial phacoemulsification combined with intraocular lens implantation between April 2013 and December 2013. The best corrected visual acuity(BCVAwas observed at 1 and 3mo after operation, and the complications were recorded.RESULTS: Compared with the preoperative, BCVA was improved at 1 and 3mo after operation, and the differences were statistically significant(PP>0.05. There was no incidence of complications, such as retinal detachment, iris damage, pupil deformation, cystoid macular edema, endophthalmitis after operation in all patients.CONCLUSION:Micro-coaxial phacoemulsification combined with intraocular lens implantation is an effective and safe method for axial high myopia with cataract.
A microscopic derivation of nuclear collective rotation-vibration model, axially symmetric case
Gulshani, Parviz
2015-01-01
We derive a microscopic version of the successful phenomenological hydrodynamic model of Bohr-Davydov-Faessler-Greiner for collective rotation-vibration motion of an axially symmetric deformed nucleus. The derivation is not limited to small oscillation amplitude. The nuclear Schrodinger equation is canonically transformed the to collective co-ordinates, which is then linearized using a constrained variational method. The associated constraints are imposed on the wavefunction rather than on th...
Modeling particulate self-healing materials and application to uni-axial compression
Herbst, Olaf; Luding, Stefan
2008-01-01
Using an advanced history dependent contact model for DEM simulations, including elasto-plasticity, viscosity, adhesion, and friction, pressure-sintered tablets are formed from primary particles. These tablets are subjected to unconfined uni-axial compression until and beyond failure. For fast and slow deformation we observe ductile-like and brittle softening, respectively. We propose a model for local self-healing that allows damage to heal during loading such that the material strength of t...
Numerical investigation of blade dynamic characteristics in an axial flow pump
Zhang Desheng; Pan Dazhi; Xu Yan; Shao Peipei; Wang Guotao
2013-01-01
The unsteady numerical simulation of fluid field and structural transient dynamic analysis of axial flow pump were carried out at three operating conditions based on fluid-structure interaction method. Numerical results show that the maximum equivalent stress of impeller occurs at the joint region of the impeller blade root and the hub, and the maximum deformation of impeller occurs at the tips of blade leading edges. The frequency-domain of the maximum equ...
Plasticity around an Axial Surface Crack in a Cylindrical Shell
Krenk, Steen
1979-01-01
field in an axially cracked cylindrical shell arising from use of classical eighth order shallow shell theory is removed when use is made of a tenth order shell theory which accounts for transverse shear deformations. Although the membrane stresses are only moderately affected, the influence on the...... Ratwani,3–5 it generalises Dugdale's assumption of a concentrated yield zone in the plane of the crack but, contrary to that model, transverse shear effects are included and a continuous stress distribution is assumed in the yield zone. The inherent difficulties arising from the use of shell theory to...... model a three-dimensional problem can be overcome when the crack is sufficiently deep and the material is so ductile that full yield of the section around the crack develops before failure. In that case the calculations confirm the initial assumption of separation of the crack surfaces and the sides of...
Energy harvesting efficiency of piezoelectric flags in axial flows
Michelin, Sebastien
2012-01-01
Self-sustained oscillations resulting from fluid-solid instabilities, such as the flutter of a flexible flag in axial flow, can be used to harvest energy if one is able to convert the solid energy into electricity. Here, this is achieved using piezoelectric patches attached to the surface of the flag that convert the solid deformation into an electric current powering purely resistive output circuits. Nonlinear numerical simulations in the slender-body limit, based on an explicit description of the coupling between the fluid-solid and electric systems, are used to determine the harvesting efficiency of the system, namely the fraction of the flow kinetic energy flux effectively used to power the output circuit, and its evolution with the system's parameters. The role of the tuning between the characteristic frequencies of the fluid-solid and electric systems is emphasized, as well as the critical impact of the piezoelectric coupling intensity. High fluid loading, classically associated with destabilization by ...
Nonlinear flap-lag axial equations of a rotating beam
Kaza, K. R. V.; Kvaternik, R. G.
1977-01-01
It is possible to identify essentially four approaches by which analysts have established either the linear or nonlinear governing equations of motion for a particular problem related to the dynamics of rotating elastic bodies. The approaches include the effective applied load artifice in combination with a variational principle and the use of Newton's second law, written as D'Alembert's principle, applied to the deformed configuration. A third approach is a variational method in which nonlinear strain-displacement relations and a first-degree displacement field are used. The method introduced by Vigneron (1975) for deriving the linear flap-lag equations of a rotating beam constitutes the fourth approach. The reported investigation shows that all four approaches make use of the geometric nonlinear theory of elasticity. An alternative method for deriving the nonlinear coupled flap-lag-axial equations of motion is also discussed.
Axial dependence of optical weak measurements in the critical region
Araujo, Manoel P; Maia, Gabriel G
2015-01-01
The interference between optical beams of different polarizations plays a fundamental role in reproducing the optical analog of the electron spin weak measurement. The extraordinary point in optical weak measurements is represented by the possibility to estimate with great accuracy the Goos-Haenchen (GH) shift by measuring the distance between the peak of the outgoing beams for two opposite rotation angles of the polarizers located before and after the dielectric block. Starting from the numerical calculation of the GH shift, which clearly shows a frequency crossover for incidence near to the critical angle, we present a detailed study of the interference between s and p polarized waves in the critical region. This allows to determine in which conditions it is possible to avoid axial deformations and reproduce the GH curves. In view of a possible experimental implementation, we give the expected weak measurement curves for Gaussian lasers of different beam waist sizes propagating through borosilicate (BK7) an...
Axially-symmetric Neutron stars: Implication of rapid rotation
Sharma, B K
2009-01-01
Models of relativistic rotating neutron star composed of hyperon rich matter is constructed in the framework of an effective field theory in the mean-field approach. The gross properties of compact star is calculated at both static and the mass-shedding limit in the axially symmetric basis. The effect of appearance and abundance of hyperons on equation of state of dense matter and stellar properties is lineated with particular emphasis on the underlying nuclear interactions. We find that the models can explain fast rotations, which supports the existence of millisecond pulsars. An important offshoot of the present investigation is that, irrespective of the model parameters and interaction taken, the star seems to sustain faster rotations (an increase in rotational frequency up to $\\approx$ 50%) without any further deformation.
No spreading across the southern Juan de Fuca ridge axial cleft during 1994-1996
Chadwell, C.D.; Hildebrand, J.A.; Spiess, Fred N.; Morton, J.L.; Normark, W.R.; Reiss, C.A.
1999-01-01
Direct-path acoustic measurements between seafloor transponders observed no significant extension (-10 ?? 14 mm/yr) from August 1994 to September 1996 at the southern Juan de Fuca Ridge (44??40' N and 130??20' W). The acoustic path for the measurement is a 691-m baseline straddling the axial cleft, which bounds the Pacific and Juan de Fuca plates. Given an expected full-spreading rate of 56 mm/yr, these data suggest that extension across this plate boundary occurs episodically within the narrow (~1 km) region of the axial valley floor, and that active deformation is occurring between the axial cleft and the plate interior. A cleft-parallel 714-m baseline located 300 m to the west of the cleft on the Pacific plate monitored system performance and, as expected, observed no motion (+5??7 mm/yr) between the 1994 and 1996 surveys.Direct-path acoustic measurements between seafloor transponders observed no significant extension (-10 ?? 14 mm/yr) from August 1994 to September 1996 at the southern Juan de Fuca Ridge (44??40 minutes N and 130??20 minutes W). The acoustic path for the measurement is a 691-m baseline straddling the axial cleft, which bounds the Pacific and Juan de Fuca plates. Given an expected full-spreading rate of 56 mm/yr, these data suggest that extension across this plate boundary occurs episodically within the narrow (approx. 1 km) region of the axial valley floor, and that active deformation is occurring between the axial cleft and the plate interior. A cleft-parallel 714-m baseline located 300 m to the west of the cleft on the Pacific plate monitored system performance and, as expected, observed no motion (+5 ?? 7 mm/yr) between the 1994 and 1996 surveys.
Computational Study of Axial Fatigue for Peripheral Nitinol Stents
Meoli, Alessio; Dordoni, Elena; Petrini, Lorenza; Migliavacca, Francesco; Dubini, Gabriele; Pennati, Giancarlo
2014-07-01
Despite their success as primary treatment for vascular diseases, Nitinol peripheral stents are still affected by complications related to fatigue failure. Hip and knee movements during daily activities produce large and cyclic deformations of the superficial femoral artery, that concomitant to the effects of pulsatile blood pressure, may cause fatigue failure in the stent. Fatigue failure typically occurs in cases of very extended lesions, which often require the use of two or more overlapping stents. In this study, finite element models were used to study the fatigue behavior of Nitinol stents when subjected to cyclic axial compression in different conditions. A specific commercial Nitinol stent was chosen for the analysis and subjected to cyclic axial compression typical of the femoral vascular region. Three different configurations were investigated: stent alone, stent deployed in a tube, and two overlapping stents deployed in a tube. Results confirm that stent oversizing has an influence in determining both the mean and amplitude strains induced in the stent and plays an important role in determining the fatigue response of Nitinol stents. In case of overlapping stents, numerical results suggest higher amplitude strains concentrate in the region close to the overlapping portion where the abrupt change in stiffness causes higher cyclic compression. These findings help to explain the high incidence of stent fractures observed in various clinical trials located close to the overlapping portion.
Axial length variability in cataract surgery
To determine the mean axial length and biometric measures in patients undergoing cataract surgery and further compare the variability of axial length between the gender and with age. Study Design: Cross-sectional observational study. Place and Duration of Study: Eye Unit I, Department of Ophthalmology, Liaquat University of Medical and Health Sciences, Hyderabad, Pakistan from January 2010 to December 2012. Methodology: All patients referred for cataract surgery were assessed. The study included 886 eyes which were straightforward cataract cases with no other ocular problem. The data was collected for axial length, keratometric values and Intra-Ocular Lens (IOL) power prior to cataract surgery. The collected data was then analyzed using SPSS version 19 for windows software. Results: Gender based comparison showed significant difference in age, axial length, keratometric values and IOL power between the two groups (p=0.000). 86% of the eyes had an axial length between 21.00 mm and 23.99 mm. In univariate analysis there was significant (p=0.000) relation between overall age and axial length. The keratometric values ranged between 36.75 D and 52.50 D. Majority of the IOL powers ranged between 20.00 D and 23.00 D. Conclusion: The mean axial length of patients undergoing cataract surgery was 22.96 +- 1.04 mm, was comparable to Indian and Chinese population but shorter than the Western population. Females had shorter axial lengths, similar to other studies. Axial length was positively associated with age among the females, the cause of which is yet to be determined. (author)
Auchter, Neal C.; Romans, Brian W.; Hubbard, Stephen M.
2016-07-01
Slope sediments on passive and active margins deform and fail across a broad range of scales ranging from loading and sediment remobilization near the sediment-water interface to submarine landslides and mass movements that incorporate significant volumes of slope deposits. Deformational styles are characterized by updip extension and downdip compressional features that occur above a detachment surface. Conditions for failure and deformation include the presence of weak layer(s) that serve as a detachment surface, competency contrasts that allow for detachment and downslope movement, deformation above a detachment surface, and a triggering mechanism(s) that initiates failure. Slope failure processes and products are well documented at scales resolvable by seismic-reflection surveys and in instances of extensive downslope failure, but the processes and products associated with intermediate-scale slope deformation are poorly understood. Intrastratal deformation is defined as stratigraphically isolated zones of deformation bounded above and below by concordant and undeformed strata. In this study, outcrop examples of intrastratal deformation from the Upper Cretaceous Tres Pasos Formation are used to elucidate the influence of depositional architecture on slope deformation. The facies distribution associated with compensational stacking of lobe deposits is shown to have a first-order control on the location and style of deformation. Detachment planes that form in mudstone deposits associated with lobe fringe and interlobe deposits are spatially limited and deformation is restricted to interbedded sandstone and mudstone associated with off-axial lobe positions. Downslope translation was arrested by stratigraphic buttresses associated with more sandstone-prone axial deposits. Emplacement of a regionally extensive mass transport deposit is interpreted as the triggering mechanism for contemporaneous intrastratal deformation of > 60 m of underlying stratigraphy. A vertical
Wobbling excitations in strongly deformed Hf nuclei?
Two Gammasphere experiments have been performed in order to establish the possible triaxial nature of strongly deformed (SD) bands in 174Hf. A lifetime measurement, using the Doppler-shift attenuation method, confirmed the large deformation of the four previously observed bands in this nucleus with transition quadrupole moments ranging from 12.6 to 13.8 b. These values are significantly larger than those predicted for triaxial minima by ultimate cranker (UC) calculations. A thin-target, high-statistics experiment was also carried out to search for linking transitions between the SD bands. No such transitions, which represent an experimental signature for wobbling modes, were observed. Four additional SD bands were found in 174Hf together with a single SD band in 173Hf. These results indicate that the strongly deformed sequences of N∼102 Hf isotopes behave differently than the triaxial strongly deformed (TSD) bands found in Lu nuclei near N=92. The interpretation of these bands in terms of possible stable triaxial deformation is confronted with the experimental findings and UC predictions
New Anomaly of the Axial-Vector Current
HE Han-Xin
2001-01-01
By computing the axial-vector current operator equation, we find the anomalous axial-vector curl equation besides the well-known anomalous axial-vector divergence equation (the Adler-Bell-Jackiw anomaly) and discuss its implication.``
Growth-induced axial buckling of a slender elastic filament embedded in an isotropic elastic matrix
O'Keeffe, Stephen G.
2013-11-01
We investigate the problem of an axially loaded, isotropic, slender cylinder embedded in a soft, isotropic, outer elastic matrix. The cylinder undergoes uniform axial growth, whilst both the cylinder and the surrounding elastic matrix are confined between two rigid plates, so that this growth results in axial compression of the cylinder. We use two different modelling approaches to estimate the critical axial growth (that is, the amount of axial growth the cylinder is able to sustain before it buckles) and buckling wavelength of the cylinder. The first approach treats the filament and surrounding matrix as a single 3-dimensional elastic body undergoing large deformations, whilst the second approach treats the filament as a planar, elastic rod embedded in an infinite elastic foundation. By comparing the results of these two approaches, we obtain an estimate of the foundation modulus parameter, which characterises the strength of the foundation, in terms of the geometric and material properties of the system. © 2013 Elsevier Ltd. All rights reserved.
NUMERICAL PREDICTION OF COMPOSITE BEAM SUBJECTED TO COMBINED NEGATIVE BENDING AND AXIAL TENSION
MAHESAN BAVAN
2013-08-01
Full Text Available The present study has investigated the finite element method (FEM techniques of composite beam subjected to combined axial tension and negative bending. The negative bending regions of composite beams are influenced by worsen failures due to various levels of axial tensile loads on steel section especially in the regions near internal supports. Three dimensional solid FEM model was developed to accurately predict the unfavourable phenomenon of cracking of concrete and compression of steel in the negative bending regions of composite beam due to axial tensile loads. The prediction of quasi-static solution was extensively analysed with various deformation speeds and energy stabilities. The FEM model was then validated with existing experimental data. Reasonable agreements were observed between the results of FEM model and experimental analysis in the combination of vertical-axial forces and failure modes on ultimate limit state behaviour. The local failure modes known as shear studs failure, excess yielding on steel beam and crushing on concrete were completely verified by extensive similarity between the numerical and experimental results. Finally, a proper way of modelling techniques for large FEM models by considering uncertainties of material behaviour due to biaxial loadings and complex contact interactions is discussed. Further, the model is suggested for the limit state prediction of composite beam with calibrating necessary degree of the combined axial loads.
Axial Thermal Rotation of Slender Rods
Li, Dichuan; Fakhri, Nikta; Pasquali, Matteo; Biswal, Sibani Lisa
2011-05-01
Axial rotational diffusion of rodlike polymers is important in processes such as microtubule filament sliding and flagella beating. By imaging the motion of small kinks along the backbone of chains of DNA-linked colloids, we produce a direct and systematic measurement of axial rotational diffusivity of rods both in bulk solution and near a wall. The measured diffusivities decrease linearly with the chain length, irrespective of the distance from a wall, in agreement with slender-body hydrodynamics theory. Moreover, the presence of small kinks does not affect the chain’s axial diffusivity. Our system and measurements provide insights into fundamental axial diffusion processes of slender objects, which encompass a wide range of entities including biological filaments and linear polymer chains.
Relationship between water activity, deformation speed, and crispness characterization
Castro Prada, E.M.; Primo Martin, C.; Meinders, M.B.J.; Hamer, R.J.; Vliet, van T.
2009-01-01
Very little is known on the rate dependency of the fracture behavior of crispy products as a function of water activity (Aw). Therefore, the effect of deformation speed on instrumental and sensory crispness was studied as a function of Aw. Deformation speed clearly affects the transition Aw range fr
Deformable Nanolaminate Optics
Olivier, S S; Papavasiliou, A P; Barbee, T W; Miles, R R; Walton, C C; Cohn, M B; Chang, K
2006-05-12
We are developing a new class of deformable optic based on electrostatic actuation of nanolaminate foils. These foils are engineered at the atomic level to provide optimal opto-mechanical properties, including surface quality, strength and stiffness, for a wide range of deformable optics. We are combining these foils, developed at Lawrence Livermore National Laboratory (LLNL), with commercial metal processing techniques to produce prototype deformable optics with aperture sizes up to 10 cm and actuator spacing from 1 mm to 1 cm and with a range of surface deformation designed to be as much as 10 microns. The existing capability for producing nanolaminate foils at LLNL, coupled with the commercial metal processing techniques being used, enable the potential production of these deformable optics with aperture sizes of over 1 m, and much larger deformable optics could potentially be produced by tiling multiple deformable segments. In addition, based on the fabrication processes being used, deformable nanolaminate optics could potentially be produced with areal densities of less than 1 kg per square m for applications in which lightweight deformable optics are desirable, and deformable nanolaminate optics could potentially be fabricated with intrinsically curved surfaces, including aspheric shapes. We will describe the basic principles of these devices, and we will present details of the design, fabrication and characterization of the prototype deformable nanolaminate optics that have been developed to date. We will also discuss the possibilities for future work on scaling these devices to larger sizes and developing both devices with lower areal densities and devices with curved surfaces.
Computer axial tomography in geosciences
Computer Axial Tomography (CAT) is one of the most adequate non-invasive techniques for the investigation of the internal structure of a large category of objects. Initially designed for medical investigations, this technique, based on the attenuation of X- or gamma-ray (and in some cases neutrons), generates digital images which map the numerical values of the linear attenuation coefficient of a section or of the entire volume of the investigated sample. Shortly after its application in medicine, CAT has been successfully used in archaeology, life sciences, and geosciences as well as for the industrial materials non-destructive testing. Depending on the energy of the utilized radiation as well as on the effective atomic number of the sample, CAT can provide with a spatial resolution of 0.01 - 0.5 mm, quantitative as well as qualitative information concerning local density, porosity or chemical composition of the sample. At present two types of axial Computer Tomographs (CT) are in use. One category, consisting of medical as well as industrial CT is equipped with X-ray tubes while the other uses isotopic gamma-ray sources. CT provided with intense X-ray sources (equivalent to 12-15 kCi or 450-550 TBq) has the advantage of an extremely short running time (a few seconds and even less) but presents some disadvantages known as beam hardening and absorption edge effects. These effects, intrinsically related to the polychromatic nature of the X-rays generated by classical tubes, need special mathematical or physical corrections. A polychromatic X-ray beam can be made almost monochromatic by means of crystal diffraction or by using adequate multicomponent filters, but these devices are costly and considerably diminish the output of X-ray generators. In the case of CT of the second type, monochromatic gamma-rays generated by radioisotopic sources, such as 169 Yb (50.4 keV), 241 Am (59 keV), 192 Ir (310.5 and 469.1 keV ) or 137 Cs (662.7 keV), are used in combination with
Nonperturbative features of the axial current
Kopeliovich, B Z; Siddikov, M
2013-01-01
In this paper we study the nonperturbative structure of the axial current and evaluate the two-point distribution amplitudes $\\int d\\xi\\, e^{-iq...\\xi}$ in the framework of the instanton vacuum model in the leading order in $\\mathcal{O}(N_{c})$. We perform a direct numerical test of the relations between the axial current and the pion distribution amplitudes, imposed by PCAC, and found excellent agreement.
Axial Vircator for Electronic Warfare Applications
L. Drazan; R. Vrana
2009-01-01
This paper deals with a high power microwave generator with virtual cathode – vircator in axial release for electronic warfare applications. The classification of directed energy weapons microwave (DEWM) is introduced together with basic block diagrams of a particular class of DEWM. In the paper, methods for designing vircator pulsed power supply, axial vircator structure, measurement methods and experimental results are presented. The vircator in electromagnetic ammunition is powered b...
Nonperturbative Aspects of Axial Vector Vertex
ZONG Hong-Shi; CHEN Xiang-Song; WANG Fan; CHANG Chao-Hsi; ZHAO En-Guang
2002-01-01
It is shown how the axial vector current of current quarks is related to that of constituent quarks within the framework of the global color symmetry model.Gluon dressing of the axial vector vertex and the quark self-energy functions are described by the inhomogeneous Bethe-Salpeter equation in the ladder approximation and the Schwinger Dyson equation in the rainbow approximation,respectively.
An Unbroken Axial Vector Current Conservation Law
Sharafiddinov, Rasulkhozha S
2015-01-01
The mass, energy and momentum of the neutrino of a true flavor have an axial-vector nature. As a consequence, the left-handed truly neutral neutrino in an axial-vector field of emission can be converted into a right-handed one and vice versa. This predicts the unidenticality of masses, energies and momenta of neutrinos of the different components. Recognizing such a difference in masses, energies, momenta and accepting that the left-handed axial-vector neutrino and the right-handed antineutrino of true neutrality refer to long-lived C-odd leptons, and the right-handed truly neutral neutrino and the left-handed axial-vector antineutrino are of short-lived fermions of C-oddity, we would write a new CP-even Dirac equation taking into account the flavor symmetrical axial-vector mass, energy and momentum matrices. Their presence explains the spontaneous mirror symmetry violation, confirming that an axial-vector current conservation law has never violated. They reflect the availability of a mirror Minkowski space i...
Permanent Deformation of Highway Subgrade Soils
无
1999-01-01
Based on a comprehensive review of the literature and preliminary testing performed on a subgrade soil, a testing methodology for repeated load testing was established. This testing protocol was verified using data from subgrade soil. The successful application of this testing protocol on the two subgrade soils proves that it can provide consistent, reliable results. A power model was used to fit the accumulated axial strain over load repetitions with the first hundred cycles excluded from the data set. A number of factors influencing the accumulation of permanent deformation were investigated. The results indicate that confining pressure, load frequency and density are relatively minor contributors to deformation accumulation. Moisture content, deviator stress and first cycle freeze-thaw are major factors governing permanent deformation. The effects of stress history resulting from staged loading are dependent upon the level of applied deviator stress. The interpretation of the rich and consistent deformation data derived from this testing protocol provide valuable insights for transportation engineers relative to the design, construction, operation and maintenance strategy of highway subgrades as well as railway roadbeds.