WorldWideScience

Sample records for partial dislocation dipoles

  1. Formation of dislocation dipoles in irradiated graphite

    International Nuclear Information System (INIS)

    Niwase, Keisuke

    2005-01-01

    Recently, we have proposed a dislocation dipole accumulation model to explain the irradiation-induced amorphization of graphite. However, the structure of dislocation dipole in the hexagonal networks is still an open question at the atomic-level. In this paper, we propose a possible formation process of the dislocation dipole

  2. Dislocation dipole annihilation in diamond and silicon

    Energy Technology Data Exchange (ETDEWEB)

    Rabier, J; Pizzagalli, L, E-mail: jacques.rabier@univ-poitiers.fr [Institut PPRIMME, Departement de Physique et Mecanique des Materiaux - UPR 3346 CNRS, Universite de Poitiers, ENSMA - SP2MI, BP 30179, F-86962 Chasseneuil Futuroscope Cedex (France)

    2011-02-01

    The mechanism of dislocation dipole annihilation has been investigated in C and Si using atomistic calculations with the aim of studying their annihilation by-products. It is shown, in C as well as in Si, that dipole annihilation yields debris that can be depicted as a cluster of vacancies, or alternately by two internal free surfaces. These defects have no strain field and can hardly be seen using usual TEM techniques. This suggests that the brown colouration of diamond could be due to microstructures resulting from deformation mechanisms associated with dipole formation and their annihilation rather than to a climb mechanism and vacancy aggregation. In silicon where a number of dipoles have been evidenced by TEM when dislocation trails are found, such debris could be the missing link responsible for the observation of strong chemical reactivity and electrical activity in the wake of moving dislocations.

  3. Epitaxial strain relaxation by provoking edge dislocation dipoles

    Science.gov (United States)

    Soufi, A.; El-Hami, K.

    2018-02-01

    Thin solid films have been used in various devices and engineering systems such as rapid development of highly integrated electronic circuits, the use of surface coatings to protect structural materials in high temperature environments, and thin films are integral parts of many micro-electro-mechanical systems designed to serve as sensors, actuators. Among techniques of ultra-thin films deposition, the heteroepitaxial method becomes the most useful at nanoscale level to obtain performed materials in various applications areas. On the other hand, stresses that appeared during the elaboration of thin films could rise deformations and fractures in materials. The key solution to solve this problem at the nanoscale level is the nucleation of interface dislocations from free surfaces. By provoking edge dislocation dipoles we obtained a strain relaxation in thin films. Moreover, the dynamic of nucleation in edge dislocations from free lateral surfaces was also studied.

  4. Cyclic softening in annealed Zircaloy-2: Role of edge dislocation dipoles and vacancies

    Science.gov (United States)

    Sudhakar Rao, G.; Singh, S. R.; Krsjak, Vladimir; Singh, Vakil

    2018-04-01

    The mechanism of cyclic softening in annealed Zircaloy-2 at low strain amplitudes under strain controlled fatigue at room temperature is rationalized. The unusual softening due to continuous decrease in the phenomenological friction stress is found to be associated with decrease in the resistance against movement of dislocations because of the formation and easy glide of pure edge dislocation dipoles and consequent decrease in friction stress from reduction in the shear modulus. Positron annihilation spectroscopy data strongly support the increase in edge dislocation density containing jogs, from increased positron trapping and increase in annihilation lifetime.

  5. Dislocation self-organization under single slip straining and dipole properties

    International Nuclear Information System (INIS)

    Chiu, Y.-L.; Veyssiere, Patrick

    2008-01-01

    Spontaneous microstructural organization under single slip is investigated by transmission electron microscopy. The formation and the structure of dislocation entanglements are analyzed on three types of fcc-based systems, Al, Cu and TiAl, all deformed by {1 1 1} slip. Differences are found that depend on stacking fault energy and lattice friction. The importance of dipolar configurations is outlined. Selected properties of dipoles are analyzed theoretically under isotropic and anisotropic elasticity in cubic systems. At variance from screw and near-screw dipoles, the stress-free equilibrium angle of an edge dipole is little dependent on the material's elastic anisotropy. In Cu, for instance, a screw dipole is at equilibrium at around 59 deg. from the slip plane, and this angle is unchanged over a range of dislocation characters of approximately ±20 deg. On the other hand, given a dipole height, the passing stress is a maximum in the screw orientation. It is, however, not a minimum in the edge orientation. Static and dynamic dipole properties are but little affected by dissociation down to a dipole height of the order of a few times the dissociation distance

  6. The equilibrium structures of the 900 partial dislocation in silicon

    International Nuclear Information System (INIS)

    Valladares, Alexander; Sutton, A P

    2005-01-01

    We consider the free energies of the single-period (SP) and double-period (DP) core reconstructions of the straight 90 0 partial dislocation in silicon. The vibrational contributions are calculated with a harmonic model. It is found that it leads to a diminishing difference between the free energies of the two core reconstructions with increasing temperature. The question of the relative populations of SP and DP reconstructions in a single straight 90 0 partial dislocation is solved by mapping the problem onto a one-dimensional Ising model in a magnetic field. The model contains only two parameters and is solved analytically. It leads to the conclusion that for the majority of the published energy differences between the SP and DP reconstructions the equilibrium core structure is dominated by the DP reconstruction at all temperatures up to the melting point. We review whether it is possible to distinguish between the SP and DP reconstructions experimentally, both in principle and in practice. We conclude that aberration corrected transmission electron microscopy should be able to distinguish between these two core reconstructions, but published high resolution micrographs do not allow the distinction to be made

  7. Emission of partial dislocations from triple junctions of grain boundaries in nanocrystalline materials

    International Nuclear Information System (INIS)

    Gutkin, M Yu; Ovid'ko, I A; Skiba, N V

    2005-01-01

    A theoretical model is suggested that describes emission of partial Shockley dislocations from triple junctions of grain boundaries (GBs) in deformed nanocrystalline materials. In the framework of the model, triple junctions accumulate dislocations due to GB sliding along adjacent GBs. The dislocation accumulation at triple junctions causes partial Shockley dislocations to be emitted from the dislocated triple junctions and thus accommodates GB sliding. Ranges of parameters (applied stress, grain size, etc) are calculated in which the emission events are energetically favourable in nanocrystalline Al, Cu and Ni. The model accounts for the corresponding experimental data reported in the literature

  8. Structures of glide-set 90 deg. partial dislocation cores in diamond cubic semiconductors

    International Nuclear Information System (INIS)

    Beckman, S.P.; Chrzan, D.C.

    2003-01-01

    Two core reconstructions of the 90 deg. partial dislocations in diamond cubic semiconductors, the so-called single- and double-period structures, are often found to be nearly degenerate in energy. This near degeneracy suggests the possibility that both core reconstructions may be present simultaneously along the same dislocation core, with the domain sizes of the competing reconstructions dependent on temperature and the local stress state. To explore this dependence, a simple statistical mechanics-based model of the dislocation core reconstructions is developed and analyzed. Predictions for the temperature-dependent structure of the dislocation core are presented

  9. The influence of anisotropy on the core structure of Shockley partial dislocations within FCC materials

    Science.gov (United States)

    Szajewski, B. A.; Hunter, A.; Luscher, D. J.; Beyerlein, I. J.

    2018-01-01

    Both theoretical and numerical models of dislocations often necessitate the assumption of elastic isotropy to retain analytical tractability in addition to reducing computational load. As dislocation based models evolve towards physically realistic material descriptions, the assumption of elastic isotropy becomes increasingly worthy of examination. We present an analytical dislocation model for calculating the full dissociated core structure of dislocations within anisotropic face centered cubic (FCC) crystals as a function of the degree of material elastic anisotropy, two misfit energy densities on the γ-surface ({γ }{{isf}}, {γ }{{usf}}) and the remaining elastic constants. Our solution is independent of any additional features of the γ-surface. Towards this pursuit, we first demonstrate that the dependence of the anisotropic elasticity tensor on the orientation of the dislocation line within the FCC crystalline lattice is small and may be reasonably neglected for typical materials. With this approximation, explicit analytic solutions for the anisotropic elasticity tensor {B} for both nominally edge and screw dislocations within an FCC crystalline lattice are devised, and employed towards defining a set of effective isotropic elastic constants which reproduce fully anisotropic results, however do not retain the bulk modulus. Conversely, Hill averaged elastic constants which both retain the bulk modulus and reasonably approximate the dislocation core structure are employed within subsequent numerical calculations. We examine a wide range of materials within this study, and the features of each partial dislocation core are sufficiently localized that application of discrete linear elasticity accurately describes the separation of each partial dislocation core. In addition, the local features (the partial dislocation core distribution) are well described by a Peierls-Nabarro dislocation model. We develop a model for the displacement profile which depends upon

  10. Partial lifetime test of an SSC Collider dipole

    International Nuclear Information System (INIS)

    Wanderer, P.; Anerella, M.; Ganetis, G.

    1993-01-01

    Over a period of ten months, a 15 m-long, 50 mm-aperture superconducting SSC Collider dipole was taken through a series of thermal and power cycles to check for changes in performance. One quench below operating current was experienced during this period. Small changes in the coil preload and certain harmonics were observed

  11. Dislocations

    Science.gov (United States)

    ... Fitness Diseases & Conditions Infections Drugs & Alcohol School & Jobs Sports Expert Answers (Q&A) Staying Safe Videos for Educators Search English Español First Aid: ... bones become separated. Dislocations are caused by falls and hard impacts, such as in sports injuries, and are more common in teens than ...

  12. Spontaneous bilateral anterior partial in-the-bag intraocular lens dislocation following routine annual eye examination.

    Science.gov (United States)

    Ford, Joshua R; Werner, Liliana; Owen, Leah; Vasavada, Shail A; Crandall, Alan

    2014-09-01

    We present the case of an 81-year-old man with pseudoexfoliation syndrome (PXF) in whom spontaneous bilateral anterior partial in-the-bag intraocular lens (IOL) dislocation was diagnosed following a routine dilated examination that demonstrated only mild pseudophacodonesis with no evidence of subluxation. Uneventful cataract surgery with placement of single-piece hydrophobic acrylic posterior chamber IOLs had been performed in both eyes 7 years previously. Bilateral IOL repositioning with scleral fixation was performed to correct the dislocation. Postoperative examinations showed remarkable improvement in visual acuity and IOL stability. We hypothesize that zonular weakness secondary to PXF predisposed the patient to bilateral IOL partial dislocation. Pupil dilation in the setting of mild pseudophacodonesis at the time of routine examination may have been a precipitating factor. To our knowledge, bilateral IOL subluxation/dislocation has been described in a limited number of case reports. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  13. First principles simulations of antiphase defects on the SP 90{sup 0} partial dislocation in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Valladares, Alexander; Sutton, A P [Materials Modelling Laboratory, Department of Materials, University of Oxford, OX1 3PH (United Kingdom)

    2006-04-19

    We study the structure and energies of formation of antiphase defects on the single period (SP) 90{sup 0} partial dislocation in silicon using a first principles density functional method. We consider two types of antiphase defect, the type first proposed by Hirsch (1980 J. Microsc. 118 3) wholly inside the dislocation core, and another type that lies partly outside the core. Both types are stable and contain one atom which is threefold coordinated. Each of these atoms has a dangling hybrid which lies in a direction perpendicular to the dislocation line on the slip plane. We obtain values of 1.39 {+-} 0.03 eV and 1.41 {+-} 0.03 eV for the average formation energy of single antiphase defects of the inside and outside types, respectively. We have obtained, using a tight binding scheme, band structures corresponding to these two types of defect, and we find both of them to be associated with states in the gap and each dangling hybrid to contain one electron.

  14. First principles simulations of antiphase defects on the SP 900 partial dislocation in silicon

    International Nuclear Information System (INIS)

    Valladares, Alexander; Sutton, A P

    2006-01-01

    We study the structure and energies of formation of antiphase defects on the single period (SP) 90 0 partial dislocation in silicon using a first principles density functional method. We consider two types of antiphase defect, the type first proposed by Hirsch (1980 J. Microsc. 118 3) wholly inside the dislocation core, and another type that lies partly outside the core. Both types are stable and contain one atom which is threefold coordinated. Each of these atoms has a dangling hybrid which lies in a direction perpendicular to the dislocation line on the slip plane. We obtain values of 1.39 ± 0.03 eV and 1.41 ± 0.03 eV for the average formation energy of single antiphase defects of the inside and outside types, respectively. We have obtained, using a tight binding scheme, band structures corresponding to these two types of defect, and we find both of them to be associated with states in the gap and each dangling hybrid to contain one electron

  15. The equilibrium structures of the 90{sup 0} partial dislocation in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Valladares, Alexander; Sutton, A P [Materials Modelling Laboratory, Department of Materials, University of Oxford, OX1 3PH (United Kingdom)

    2005-12-07

    We consider the free energies of the single-period (SP) and double-period (DP) core reconstructions of the straight 90{sup 0} partial dislocation in silicon. The vibrational contributions are calculated with a harmonic model. It is found that it leads to a diminishing difference between the free energies of the two core reconstructions with increasing temperature. The question of the relative populations of SP and DP reconstructions in a single straight 90{sup 0} partial dislocation is solved by mapping the problem onto a one-dimensional Ising model in a magnetic field. The model contains only two parameters and is solved analytically. It leads to the conclusion that for the majority of the published energy differences between the SP and DP reconstructions the equilibrium core structure is dominated by the DP reconstruction at all temperatures up to the melting point. We review whether it is possible to distinguish between the SP and DP reconstructions experimentally, both in principle and in practice. We conclude that aberration corrected transmission electron microscopy should be able to distinguish between these two core reconstructions, but published high resolution micrographs do not allow the distinction to be made.

  16. rf Wien filter in an electric dipole moment storage ring: The “partially frozen spin” effect

    Directory of Open Access Journals (Sweden)

    William M. Morse

    2013-11-01

    Full Text Available An rf Wien filter (WF can be used in a storage ring to measure a particle’s electric dipole moment (EDM. If the WF frequency equals the spin precession frequency without WF, and the oscillating WF fields are chosen so that the corresponding transverse Lorentz force equals zero, then a large source of systematic errors is canceled but the EDM signal is not. This effect, discovered by simulation, can be called the “partially frozen spin” effect.

  17. Atomistic simulations of dislocation processes in copper

    DEFF Research Database (Denmark)

    Vegge, T.; Jacobsen, K.W.

    2002-01-01

    We discuss atomistic simulations of dislocation processes in copper based on effective medium theory interatomic potentials. Results on screw dislocation structures and processes are reviewed with particular focus on point defect mobilities and processes involving cross slip. For example......, the stability of screw dislocation dipoles is discussed. We show that the presence of jogs will strongly influence cross slip barriers and dipole stability. We furthermore present some new results on jogged edge dislocations and edge dislocation dipoles. The jogs are found to be extended, and simulations...

  18. Expansion of Shockley stacking fault observed by scanning electron microscope and partial dislocation motion in 4H-SiC

    Science.gov (United States)

    Yamashita, Yoshifumi; Nakata, Ryu; Nishikawa, Takeshi; Hada, Masaki; Hayashi, Yasuhiko

    2018-04-01

    We studied the dynamics of the expansion of a Shockley-type stacking fault (SSF) with 30° Si(g) partial dislocations (PDs) using a scanning electron microscope. We observed SSFs as dark lines (DLs), which formed the contrast at the intersection between the surface and the SSF on the (0001) face inclined by 8° from the surface. We performed experiments at different electron-beam scanning speeds, observing magnifications, and irradiation areas. The results indicated that the elongation of a DL during one-frame scanning depended on the time for which the electron beam irradiated the PD segment in the frame of view. From these results, we derived a formula to express the velocity of the PD using the elongation rate of the corresponding DL during one-frame scanning. We also obtained the result that the elongation velocity of the DL was not influenced by changing the direction in which the electron beam irradiates the PD. From this result, we deduced that the geometrical kink motion of the PD was enhanced by diffusing carriers that were generated by the electron-beam irradiation.

  19. Nucleation of dislocations from [0 0 1] bicrystal interfaces in aluminum

    International Nuclear Information System (INIS)

    Spearot, Douglas E.; Jacob, Karl I.; McDowell, David L.

    2005-01-01

    It is well established from molecular dynamics simulations that grain boundaries in nanocrystalline samples serve as sources of dislocations. In this work, we use molecular dynamics simulations to study the mechanisms associated with dislocation nucleation from bicrystal [0 0 1] interfaces in aluminum. Three interface misorientations are studied, including the Σ5 (3 1 0) boundary, which has a high density of coincident atomic sites. Molecular dynamics simulations show that full dislocation loops are nucleated from each interface during uniaxial tension. After the second partial dislocation is emitted, a ledge remains within the interface at the intersection of the slip plane and the bicrystal boundary. A disclination dipole model is proposed for the structure of the distorted interface accounting for local lattice rotations and the ledge at the nucleation site

  20. Results from a partial lifetime test of a 40 mm-aperture 17 mm SSC model dipole

    International Nuclear Information System (INIS)

    Radusewicz, P.; Devred, A.; Bush, T.; Coombes, R.; DiMarco, J.; Goodzeit, C.; Kuzminski, J.; Ogitsu, T.; Potter, J.; Puglisi, M.; Sanger, P.; Schermer, R.; Tompkins, J.; Yu, Y.; Zhao, Y.; Zheng, H.; Anerella, M.; Cottingham, J.; Ganetis, G.; Garber, M.; Ghosh, A.; Greene, A.; Gupta, R.; Jain, A.; Kahn, S.; Kelly, E.; Morgan, G.; Muratore, J.; Prodell, A.; Rehak, M.; Roher, E.P.; Sampson, W.; Shutt, R.; Thomas, R.; Thompson, P.; Wanderer, P.; Willen, E.; Bleadon, M.; Hanft, R.; Kuchnir, M.; Mantsch, P.; Mazur, P.O.; Orris, D.; Peterson, T.; Strait, J.; Royett, J.; Scanlan, R.; Taylor, C.

    1992-03-01

    A 40-mm-aperture, 17-m-long Superconducting Super Collider (SSC) model dipole was assembled at Brookhaven National Laboratory (BNL) and tested initially at Fermi National Accelerator Lab (FNAL) and later at BNL. At BNL an extended cycle test was devised to examine the magnet's performance through numerous cold tests and thermal cycles. This paper discusses the magnet's mechanical and quench performance and magnet field measurements during the tests

  1. [Elbow dislocation].

    Science.gov (United States)

    de Pablo Márquez, B; Castillón Bernal, P; Bernaus Johnson, M C; Ibañez Aparicio, N M

    Elbow dislocation is the most frequent dislocation in the upper limb after shoulder dislocation. Closed reduction is feasible in outpatient care when there is no associated fracture. A review is presented of the different reduction procedures. Copyright © 2017 Sociedad Española de Médicos de Atención Primaria (SEMERGEN). Publicado por Elsevier España, S.L.U. All rights reserved.

  2. Subtalar dislocation

    International Nuclear Information System (INIS)

    El-Khoury, G.Y.; Yousefzadeh, D.K.; Mulligan, G.M.; Moore, T.E.

    1982-01-01

    Over a period of three years we have seen nine patients with subtalar dislocation, all of whom sustained violent trauma to the region of the ankle and hind foot. All but one patient were males. Clinically a subtalar dislocation resembles a complicated fracture dislocation of the ankle but a definitive diagnosis can only be made radiographically. The mechanism of injury and radiographic features of this injury are discussed. (orig.)

  3. Nature of Dislocations in Silicon

    DEFF Research Database (Denmark)

    Hansen, Lars Bruno; Stokbro, Kurt; Lundqvist, Bengt

    1995-01-01

    Interaction between two partial 90 degrees edge dislocations is studied with atomic-scale simulations using the effective-medium tight-binding method. A large separation between the two dislocations (up to 30 Angstrom), comparable to experimental values, is achieved with a solution of the tight-b...

  4. ACOL dipoles

    International Nuclear Information System (INIS)

    Vlogaert, J.

    1987-01-01

    This paper describes the general design of ACOL dipoles, including the special injection area dipole. A list of mechanical, electrical and magnetic parameters and results of magnetic measurements are presented. Particular attention is paid to the proximity effects between quadrupoles and dipoles

  5. Atomistic simulation of hydrogen dynamics near dislocations in vanadium hydrides

    International Nuclear Information System (INIS)

    Ogawa, Hiroshi

    2015-01-01

    Highlights: • Hydrogen–dislocation interaction was simulated by molecular dynamics method. • Different distribution of H atoms were observed at edge and screw dislocation. • Planner distribution of hydrogen may be caused by partialized edge dislocation. • Hydrogen diffusivity was reduced in both edge and screw dislocation models. • Pipe diffusion was observed for edge dislocation but not for screw dislocation. - Abstract: Kinetics of interstitial hydrogen atoms near dislocation cores were analyzed by atomistic simulation. Classical molecular dynamics method was applied to model structures of edge and screw dislocations in α-phase vanadium hydride. Simulation showed that hydrogen atoms aggregate near dislocation cores. The spatial distribution of hydrogen has a planner shape at edge dislocation due to dislocation partialization, and a cylindrical shape at screw dislocation. Simulated self-diffusion coefficients of hydrogen atoms in dislocation models were a half- to one-order lower than that of dislocation-free model. Arrhenius plot of self-diffusivity showed slightly different activation energies for edge and screw dislocations. Directional dependency of hydrogen diffusion near dislocation showed high and low diffusivity along edge and screw dislocation lines, respectively, hence so called ‘pipe diffusion’ possibly occur at edge dislocation but does not at screw dislocation

  6. Structure of the Dislocation in Sapphire

    DEFF Research Database (Denmark)

    Bilde-Sørensen, Jørgen; Thölen, A. R.; Gooch, D. J.

    1976-01-01

    Experimental evidence of the existence of 01 0 dislocations in the {2 0} prism planes in sapphire has been obtained by transmission electron microscopy. By the weak-beam technique it has been shown that the 01 0 dislocations may dissociate into three partials. The partials all have a Burgers vector...... of ⅓ 01 0 and are separated by two identical faults. The distance between two partials is in the range 75-135 Å, corresponding to a fault energy of 320±60 mJ/m2. Perfect 01 0 dislocations have also been observed. These dislocations exhibited either one or two peaks when imaged in the (03 0) reflection...

  7. Perilunate Dislocation

    Directory of Open Access Journals (Sweden)

    John Jiao

    2016-09-01

    Full Text Available History of present illness: A 25-year-old female presented to the emergency department with left wrist pain following a fall off a skateboard. The patient fell on her outstretched left wrist with the wrist dorsiflexed and reported immediate sharp pain to her left wrist that was worse with movement. She denied other trauma. Significant findings: In the left lateral wrist x-ray, the lunate (outlined in blue is dislocated from the rest of the wrist bones (yellow line but still articulates with the radius (red line. The capitate (yellow line does not sit within the distal articulation of the lunate and is displaced dorsally. Additionally, a line drawn through the radius and lunate (green line fails to intersect with the capitate. This is consistent with a perilunate dislocation. This is compared to a lunate dislocation, where the lunate itself is displaced and turned ventrally (spilled teacup and the proximal aspect does not articulate with the radius. Discussion: A perilunate dislocation is a significant closed wrist injury that is easily missed on standard anterior-posterior imaging. These dislocations are relatively rare, involving only 7% of all carpal injuries and are associated with high-energy trauma onto a hyperextended wrist, such as falls from a height, motor vehicle accidents, and sports injuries.1 An untreated perilunate dislocation is associated with high risk of chronic carpal instability and post-traumatic arthritis. If the mechanism of injury is sufficient to suspect perilunate dislocation, multiple radiographic views of the wrist should be ordered. Patients should receive prompt orthopedic consultation for open reduction and ligamentous repair. Even after successful identification and subsequent surgical repair, median nerve neuropathy and post-traumatic arthritis are frequent.2-3

  8. Internal stresses, dislocation mobility and ductility

    Science.gov (United States)

    Saada, G.

    1991-06-01

    The description of plastic deformation must take into account individual mechanisms and heterogeneity of plastic strain. Influence of dislocation interaction with forest dislocations and of cross slip are connected with the organization of dipole walls. The latter are described and their development is explained as a consequence of edge effects. Applications are discussed. La description de la déformation plastique doit prendre en compte les interactions individuelles des dislocations et l'hétérogénéité à grande échelle de la déformation plastique. Les interactions des dislocations mobiles avec la forêt de dislocations, le glissement dévié, ont pour effet la création de parois dipolaires. Celles-ci sont décrites et leur développement est appliqué à partir des effets de bord.

  9. [Classification and Treatment of Sacroiliac Joint Dislocation].

    Science.gov (United States)

    Tan, Zhen; Huang, Zhong; Li, Liang; Meng, Wei-Kun; Liu, Lei; Zhang, Hui; Wang, Guang-Lin; Huang, Fu-Guo

    2017-09-01

    % fracture healing. Two cases were identified as type Ⅰ sacroiliac joint dislocation,including one with coexistence of nerve injury. Patients recovered completely 12 months after surgery. Eight cases were identified as type Ⅱ sacroiliac joint dislocation; none had obvious nerve injury during treatments. Twelve cases were identified as type Ⅲ sacroiliac joint dislocation,including one with coexistence of nerve injury. Patients recovered completely 12 months after surgery. Three cases were identified as type Ⅳ sacroiliac joint dislocation with coexistence of nerve injury. Two patients fully recovered 12 months after surgery. One had partial recovery of neurological function. The classification and treatment regimen for sacroiliac joint dislocation have achieved better therapeutic effect,which is worth promoting.

  10. Dislocation Arrangements in Deformed and Neutron Irradiated Zirconium and Zircaloy-2

    International Nuclear Information System (INIS)

    Roy, R.B.

    1963-12-01

    Dislocation arrangements in deformed and neutron irradiated Zr and Zircaloy-2 have been studied by thin film transmission electron microscopy. Results indicate that the prominent slip system, in both Zr and Zircaloy-2, is the {1010} 1/3 type; no evidence for basal slip was observed. Attractive and repulsive dislocation interactions seem to be more important than the intersection jog reactions. Elongated loops and dipoles were seen at higher deformations and it is suspected that such loops or dipoles are formed due to interactions between dislocations lying in parallel planes. Stacking fault ribbons lying in {1010} plane have been found in 15% cold rolled Zircaloy-2: a rough estimate of stacking fault energy indicates that it is ∼ 65 ergs/cm 2 . Calculations show that the equilibrium separation of partials is ∼ 60 A and a stress as high as 19x10 -3 μ acting along {0010} direction is needed to separate them. It has been suggested that O 2 and N 2 in addition to their solid solution hardening effect may also cause a lowering of the stacking fault energy and Suzuki hardening

  11. Dislocation Arrangements in Deformed and Neutron Irradiated Zirconium and Zircaloy-2

    Energy Technology Data Exchange (ETDEWEB)

    Roy, R B

    1963-12-15

    Dislocation arrangements in deformed and neutron irradiated Zr and Zircaloy-2 have been studied by thin film transmission electron microscopy. Results indicate that the prominent slip system, in both Zr and Zircaloy-2, is the {l_brace}1010{r_brace} 1/3 <1210> type; no evidence for basal slip was observed. Attractive and repulsive dislocation interactions seem to be more important than the intersection jog reactions. Elongated loops and dipoles were seen at higher deformations and it is suspected that such loops or dipoles are formed due to interactions between dislocations lying in parallel planes. Stacking fault ribbons lying in {l_brace}1010{r_brace} plane have been found in 15% cold rolled Zircaloy-2: a rough estimate of stacking fault energy indicates that it is {approx} 65 ergs/cm{sup 2}. Calculations show that the equilibrium separation of partials is {approx} 60 A and a stress as high as 19x10{sup -3} {mu} acting along {l_brace}0010{r_brace} direction is needed to separate them. It has been suggested that O{sub 2} and N{sub 2} in addition to their solid solution hardening effect may also cause a lowering of the stacking fault energy and Suzuki hardening.

  12. Dislocation morphology in deformed and irradiated niobium

    International Nuclear Information System (INIS)

    Chang, C.P.

    1977-06-01

    Niobium foils of moderate purity were examined for the morphology of dislocations or defect clusters in the deformed or neutron-irradiated state by transmission electron microscopy. New evidence has been found for the dissociation of screw dislocations into partials on the (211) slip plane according to the Crussard mechanism: (a/2) [111] → (a/3) [111] + (a/6) [111

  13. Effect of collision cascades on dislocations in tungsten: A molecular dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Fu, B.Q., E-mail: bqfu@scu.edu.cn [Key Laboratory for Radiation Physics and Technology, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610065 (China); Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Fitzgerald, S.P. [Department of Applied Mathematics, University of Leeds, Leeds LS2 9JT (United Kingdom); Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Hou, Q.; Wang, J.; Li, M. [Key Laboratory for Radiation Physics and Technology, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610065 (China)

    2017-02-15

    Highlights: • A cascde near a dislocation promotes climb motion. • Kinks induced by cascade facilitate the dipoles motion toward the cascade. • Shearing of dipole is dependent on PKA energy, position, direction, and dipole width. - Abstract: Tungsten (W) is the prime candidate material for the divertor and other plasma-facing components in DEMO. The point defects (i.e. vacancies and self-interstitials) produced in collision cascades caused by incident neutrons aggregate into dislocation loops (and voids), which strongly affect the mechanical properties. The point defects also interact with existing microstructural features, and understanding these processes is crucial for modelling the long term microstructural evolution of the material under fusion conditions. In this work, we performed molecular dynamics simulations of cascades interacting with initially straight edge dislocation dipoles. It was found that the residual vacancy number usually exceeds the residual interstitial number for cascades interacting with vacancy type dipoles, but for interstitial type dipoles these are close. We observed that a cascade near a dislocation promotes climb, i.e. it facilitates the movement of point defects along the climb direction. We also observed that the dislocations move easily along the glide direction, and that kinks are formed near the centre of the cascade, which then facilitate the movement of the dipoles. Some dipoles are sheared off by the cascade, and this is dependent on PKA energy, position, direction, and the width of dipole.

  14. Dissociated dislocations in Ni: a computational study

    International Nuclear Information System (INIS)

    Szelestey, P.; Patriarca, M.; Kaski, K.

    2005-01-01

    A systematic computational study of the behavior of a (1/2) dissociated screw dislocation in fcc nickel is presented, in which atomic interactions are described through an embedded-atom potential. A suitable external stress is applied on the system, both for modifying the equilibrium separation distance d and moving the dislocation complex. The structure of the dislocation and its corresponding changes during the motion are studied in the framework of the two-dimensional Peierls model, for different values of the ratio d/a', where a' is the period of the Peierls potential. The distance between the edge and screw components of the partials, as well as their widths, undergo a modulation with period a', as the dislocation moves, and the amplitudes of such oscillations are shown to depend on d/a'. The stress profile acting on the dislocation complex is analyzed and the effective Peierls stress is estimated for different values of d/a'

  15. Dipole defects in beryl

    International Nuclear Information System (INIS)

    Holanda, B A; Cordeiro, R C; Blak, A R

    2010-01-01

    Dipole defects in gamma irradiated and thermally treated beryl (Be 3 Al 2 Si 6 O 18 ) samples have been studied using the Thermally Stimulated Depolarization Currents (TSDC) technique. TSDC experiments were performed in pink (morganite), green (emerald), blue (aquamarine) and colourless (goshenite) natural beryl. TSDC spectra present dipole peaks at 190K, 220K, 280K and 310K that change after gamma irradiation and thermal treatments. In morganite samples, for thermal treatments between 700K and 1100K, the 280K peak increase in intensity and the band at 220K disappears. An increase of the 280K peak and a decrease of the 190K peak were observed in the TSDC spectra of morganite after a gamma irradiation of 25kGy performed after the thermal treatments. In the case of emerald samples, thermal treatments enhanced the 280K peak and gamma irradiation partially destroyed this band. The goshenite TSDC spectra present only one band at 280K that is not affected either by thermal treatments or by gamma irradiation. All the observed peaks are of dipolar origin because the intensity of the bands is linearly dependent on the polarization field, behaviour of dipole defects. The systematic study, by means of TSDC measurements, of ionizing irradiation effects and thermal treatments in these crystals makes possible a better understanding of the role played by the impurities in beryl crystals.

  16. Electron-dislocation interaction at low temperatures. Progress report

    International Nuclear Information System (INIS)

    1976-01-01

    Studies of the interaction of mobile dislocations with electrons have shown that dislocation motion can be, in part, described by treating the dislocation as an underdamped oscillator. In particular, studies in lead alloys have shown tht dislocation motion can be considered as the motion of string, slightly damped by electrons, without regard for any other lattice friction. In addition we have shown that silver solutes, in lead crystals, occupy, partially, interstitial sites. Finally, we have shown that dislocations in copper interact, unexpectedly, with electrons. This is shown by measuring the influence of a magnetic field on the flow stress of copper crystals at 4.2 0 K

  17. Dislocation-dynamics method

    International Nuclear Information System (INIS)

    Van Brutzel, L.

    2015-01-01

    Dislocation-Dynamics (DD) technique is identified as the method able to model the evolution of material plastic properties as a function of the microstructural transformation predicted at the atomic scale. Indeed, it is the only simulation method capable of taking into account the collective behaviour of a large number of dislocations inside a realistic microstructure. DD simulations are based on the elastic dislocation theory following rules inherent to the dislocation core structure often call 'local rules'. All the data necessary to establish the local rules for DD have to come directly from experiment or alternatively from simulations carried out at the atomic scale such as molecular dynamics or ab initio calculations. However, no precise information on the interaction between two dislocations or between dislocations and defects induced by irradiation are available for nuclear fuels. Therefore, in this article the DD technique will be presented and some examples are given of what can be achieved with it. (author)

  18. Primary traumatic patellar dislocation

    Directory of Open Access Journals (Sweden)

    Tsai Chun-Hao

    2012-06-01

    Full Text Available Abstract Acute traumatic patellar dislocation is a common injury in the active and young adult populations. MRI of the knee is recommended in all patients who present with acute patellar dislocation. Numerous operative and non-operative methods have been described to treat the injuries; however, the ideal management of the acute traumatic patellar dislocation in young adults is still in debate. This article is intended to review the studies to the subjects of epidemiology, initial examination and management.

  19. Transition pathways in the unfaulting of dislocation loops

    International Nuclear Information System (INIS)

    Kubota, Alison; Wolfer, W.G.

    2005-01-01

    In order to study the dynamic mechanism of loop unfaulting, we performed large-scale classical molecular dynamics simulations involving computational cells with several millions of atoms. To induce dislocation loop unfaulting, we launched 1 ps duration traction stress pulses at a free surface of the computational box. In many cases, we observe unfaulting to involve both intuitive and complex dislocation processes with multiple Shockley partial dislocations. However, in some instances, we observe unfaulting to occur by a sudden instability of the stacking fault without clear traces of dislocation reactions

  20. Dependence of dislocation structure on orientation and slip systems in highly oriented nanotwinned Cu

    DEFF Research Database (Denmark)

    Lu, Qiuhong; You, Zesheng; Huang, Xiaoxu

    2017-01-01

    slip Mode I and II are active with dominance of Mode II. In structures deformed at 45° dislocations from slip Modes I, II and III are identified, where Mode III dislocations consist of partial dislocations moving along the TBs and full dislocations inside the twin lamellae gliding on the slip planes...... parallel to the twin plane. The analysis of the dislocation structures illustrate the strong correlation between active slip systems and the dislocation structure and the strong effect of slip mode anisotropy on both the flow stress and strain hardening rate of nanotwinned Cu....

  1. Metastablity of the undissociated state of dissociated dislocations

    International Nuclear Information System (INIS)

    Takeuchi, Shin

    2005-01-01

    Undissociated, metastable dislocations have been observed in various crystals in addition to stable dissociated dislocations by high-resolution transmission electron microscopy. The origin of the metastablity of the undissociated state has been discussed specifically for the dissociation into Shockley partial dislocations in fcc or hcp lattice. It is shown that the metastability is due either to a high Peierls-Nabarro stress larger than a few percent of the shear modulus of the partial dislocations and/or to the increase of the total core energy by an increase of the dangling bonds. The metastablity of undissociated dislocations in zincblende III-V compounds is concluded to be due to a contribution of the latter effect

  2. Plastic deformation of uranium dioxide: observation of the sub-structures of dislocations

    International Nuclear Information System (INIS)

    Alamo, A.; Lefebvre, J.M.; Soullard, J.

    1978-01-01

    Single crystals of uranium dioxide were deformed in compression at imposed strain rates in the temperature range of 700 0 C to 1400 0 C. The crystals were oriented to promote slip over one or two slip systems of the family [100] and also on the [110] system. Thin films of the deformed specimens were examined by transmission electron microscopy. When [100] single glide system operates, the dislocation substructure consist of numerous dipoles, their edge components lying along directions. For the [100] double glide system the grain boundaries and dislocation hexagonal network are observed, the complexity of which increases with the nominal strain. Dislocation arrangments consisting of extensive cellular networks of tangling dislocations and hexagonal netting were detected for [110] system. The auxillary role of [111] planes on the dislocation cross slip from [100] and [110] system was demonstrated. Weak beam images suggest that dissociation of dislocations can occur. (Auth.)

  3. Dislocation: First Aid

    Science.gov (United States)

    ... or a collision during contact or high-speed sports. Dislocation usually involves the body's larger joints. In adults, the most common site of the injury is the shoulder. In children, it's the elbow. ...

  4. Broken or dislocated jaw

    Science.gov (United States)

    ... broken or dislocated jaw requires prompt medical attention. Emergency symptoms include difficulty breathing or heavy bleeding. ... safety equipment, such as a helmet when playing football, or using ... can prevent or minimize some injuries to the face or jaw.

  5. Dislocations and melting in two and three dimensions

    DEFF Research Database (Denmark)

    Tallon, Jeffery L.

    1980-01-01

    included, the model system may jump discontinuously from a volume below the dislocation transition to a volume above the disclination transition so that both transitions are virtual and are hidden in the first-order discontinuity. A reinterpretation of the recent molecular-dynamics simulation of two-dimensional......Comments are presented on the recent theories of two-dimensional melting which envisage melting as proceeding via two second-order transitions comprising dislocation dipole dissociation followed by disclination dipole dissociation. It is suggested that if the configurational entropy is properly...... melting of Frenkel and McTague, reveals that such is the case for a Lennard-Jones system. There may be no fundamental difference between two-and three-dimensional melting. ©1980 The American Physical Society...

  6. Dislocation mechanism of void growth at twin boundary of nanotwinned nickel based on molecular dynamics simulation

    International Nuclear Information System (INIS)

    Zhang, Yanqiu; Jiang, Shuyong; Zhu, Xiaoming; Zhao, Yanan

    2016-01-01

    Molecular dynamics simulation was performed to investigate dislocation mechanism of void growth at twin boundary (TB) of nanotwinned nickel. Simulation results show that the deformation of nanotwinned nickel containing a void at TB is dominated by the slip involving both leading and trailing partials, where the trailing partials are the dissociation products of stair-rod dislocations formed by the leading partials. The growth of a void at TB is attributed to the successive emission of the leading partials followed by trailing partials as well as the escape of these partial dislocations from the void surface. - Highlights: • Dislocation mechanism of void growth at TB of nanotwinned nickel is investigated. • Deformation of the nanotwinned nickel is dominated by leading and trailing partials. • Growth of void at TB is caused by successive emission and escape of these partials.

  7. High-voltage electron-microscopical observation of crack-tip dislocations in silicon crystals

    International Nuclear Information System (INIS)

    Tanaka, Masaki; Higashida, Kenji

    2005-01-01

    Crack-tip dislocations in silicon single crystals were observed by high-voltage electron microscopy. Cracks were introduced into silicon wafers at room temperature by a Vickers indenter. The indented specimens were annealed at 823 K in order to activate dislocation emission from the crack tip under the residual stress due to the indentation. In the specimen without annealing, no dislocations were observed around the crack. On the other hand, in the specimen after the annealing, the aspect of the early stage of dislocation emission was observed, where dislocations were emitted not as a perfect dislocation but as a partial dislocation in the hinge-type plastic zone. Prominent dislocation arrays that were emitted from a crack tip were also observed, and they were found to be of shielding type, which increases the fracture toughness of those crystals

  8. Electric dipole moments reconsidered

    International Nuclear Information System (INIS)

    Rupertsberger, H.

    1989-01-01

    The electric dipole moments of elementary particles, atoms, molecules and their connection to the electric susceptibility are discussed for stationary states. Assuming rotational invariance it is emphasized that for such states only in the case of a parity and time reversal violating interaction the considered particles can obtain a nonvanishing expectation value for the electric dipole moment. 1 fig., 13 refs. (Author)

  9. Dislocation structure evolution and characterization in the compression deformed Mn-Cu alloy

    International Nuclear Information System (INIS)

    Zhong, Y.; Yin, F.; Sakaguchi, T.; Nagai, K.; Yang, K.

    2007-01-01

    Dislocation densities and dislocation structure arrangements in cold compressed polycrystalline commercial M2052 (Mn-20Cu-5Ni-2Fe) high damping alloy with various strains were determined in scanning mode by X-ray peak profile analysis and electron backscatter diffraction (EBSD). The results indicate that the Mn-Cu-Ni-Fe alloy has an evolution behavior quite similar to the dislocation structure in copper. The dislocation arrangement parameter shows a local minimum in the transition range between stages III and IV that can be related to the transformation of the dislocation arrangement in the cell walls from a polarized dipole wall (PDW) into a polarized tile wall (PTW) structure. This evolution is further confirmed by the results of local misorientation determined by EBSD. In addition, during deformation, the multiplication of dislocation densities in the MnCu alloy is significantly slower than that in copper, and the transition of the dislocation structure is strongly retarded in the MnCu alloy compared with copper. These results can be explained by the mechanism of elastic anisotropy on the dislocation dynamics, as the elastic anisotropy in the MnCu alloy is larger than that in copper, which can strongly retard the multiplication of the dislocation population and the transformation of the dislocation structure. These results are important for research into the plastic working behavior of Mn-Cu-Ni-Fe high damping alloy

  10. UNK superconducting dipole development

    International Nuclear Information System (INIS)

    Ageev, A.I.; Andreev, N.I.; Balbekov, V.I.

    1987-01-01

    For choozing the design of superconducting dipoles (SCD) for the IHEP UNK the test results for SCD with warm and cold iron are given. The main parameters of dipoles are presented. The SCD designs are described. At present works on SP magnet simulation for UNK are carried out in two directions. Tests are conducted on a rig with a chain of series dipoles with a warm magnetic screen. The purpose of these tests is to study heat exchange and hydraulics in magnets, energy and helium evacuation in emergency magnet transition into normal conditions, simulation of possible cooling and heating schemes. Another direction involves production of short and full-scale dipole models with cold iron and their testing on rigs. The final choice of the dipole design for commercial production is planned for 1987

  11. Dislocation Dynamics During Plastic Deformation

    CERN Document Server

    Messerschmidt, Ulrich

    2010-01-01

    The book gives an overview of the dynamic behavior of dislocations and its relation to plastic deformation. It introduces the general properties of dislocations and treats the dislocation dynamics in some detail. Finally, examples are described of the processes in different classes of materials, i.e. semiconductors, ceramics, metals, intermetallic materials, and quasicrystals. The processes are illustrated by many electron micrographs of dislocations under stress and by video clips taken during in situ straining experiments in a high-voltage electron microscope showing moving dislocations. Thus, the users of the book also obtain an immediate impression and understanding of dislocation dynamics.

  12. Computer simulation of the interaction between an extended dislocation and radiation defects in the fcc lattice

    International Nuclear Information System (INIS)

    Kuramoto, E.; Nakamura, Y.; Tsutsumi, T.

    1993-01-01

    The interaction between an extended dislocation and a radiation-induced defect, especially, a self-interstitial atom (SIA), has been investigated in the model fcc lattice by computer simulation technique. An SIA was absorbed into the core of one of the two partial dislocations of the extended screw dislocation as a crowdion which extends along the dislocation line. Under the applied shear stress this crowdion acted as a pinning point, resulting in irradiation hardening. On the other hand, an SIA was absorbed at the jog site of the extended edge dislocation (at one of the two jog sites on two partial dislocations) and after some relaxation the total jog was shifted to one atomic distance through the spreading out of the strain due to an SIA from one partial side to the other side. (orig.)

  13. Dislocation climb models from atomistic scheme to dislocation dynamics

    OpenAIRE

    Niu, Xiaohua; Luo, Tao; Lu, Jianfeng; Xiang, Yang

    2016-01-01

    We develop a mesoscopic dislocation dynamics model for vacancy-assisted dislocation climb by upscalings from a stochastic model on the atomistic scale. Our models incorporate microscopic mechanisms of (i) bulk diffusion of vacancies, (ii) vacancy exchange dynamics between bulk and dislocation core, (iii) vacancy pipe diffusion along the dislocation core, and (iv) vacancy attachment-detachment kinetics at jogs leading to the motion of jogs. Our mesoscopic model consists of the vacancy bulk dif...

  14. Dislocation of jaws

    International Nuclear Information System (INIS)

    Katzberg, R.W.; Hayakawa, K.; Anderson, Q.N.; Manzione, J.V.; Helms, C.A.; Tallents, R.

    1984-01-01

    Pluri-directional tomographic and arthrotomographic findings are described in six patients with dislocation of the jaw severe enough to require medical assistance. A grooved defect along the posterior aspect of the condylar head was noted in two of the six patients. The arthrotomographic findings that were obtained in one patient that was dislocated at the time of the arthrogram did not suggest a meniscocondyle incoordination as a mechanism. However, arthrotomographic findings in the six reported cases suggest that significant intra-articular soft tissue damage may result. (orig.)

  15. Influence of Elastic Anisotropy on Extended Dislocation Nodes

    Energy Technology Data Exchange (ETDEWEB)

    Pettersson, B

    1971-09-15

    The interaction forces between the partial dislocations forming an extended dislocation node are calculated using elasticity theory for anisotropic media.s are carried out for nodes of screw, edge and mixed character in Ag, which has an anisotropy ratio A equal to 3, and in a hypothetic material with A = 1 and the same shear modulus as Ag. The results are compared with three previous theories using isotropic elasticity theory. As expected, in Ag the influence of anisotropy is of the same order as the uncertainty due to the dislocation core energy

  16. Simulation of dislocation glide in dilute Fe-Cu alloys

    International Nuclear Information System (INIS)

    Tapasa, K.; Bacon, D.J.; Osetsky, Yu.N.

    2005-01-01

    The effects on dislocation glide of the substitutional element copper in solution in α-iron are being investigated by computer simulation. In the first phase, the critical stress for a 1/2 {110} edge dislocation to overcome configurations of either a single or two nearest-neighbour solute atoms is simulated. Molecular statics and dynamics methods are used to simulate effects at temperature equal to and greater than 0K, respectively. Single copper atoms and nearest-neighbour pairs in the first atomic plane below the glide plane give the strongest barrier to dislocation glide, in partial agreement with elasticity theory. In addition to temperature, obstacle-spacing effects are considered

  17. Changes in earth's dipole.

    Science.gov (United States)

    Olson, Peter; Amit, Hagay

    2006-11-01

    The dipole moment of Earth's magnetic field has decreased by nearly 9% over the past 150 years and by about 30% over the past 2,000 years according to archeomagnetic measurements. Here, we explore the causes and the implications of this rapid change. Maps of the geomagnetic field on the core-mantle boundary derived from ground-based and satellite measurements reveal that most of the present episode of dipole moment decrease originates in the southern hemisphere. Weakening and equatorward advection of normal polarity magnetic field by the core flow, combined with proliferation and growth of regions where the magnetic polarity is reversed, are reducing the dipole moment on the core-mantle boundary. Growth of these reversed flux regions has occurred over the past century or longer and is associated with the expansion of the South Atlantic Anomaly, a low-intensity region in the geomagnetic field that presents a radiation hazard at satellite altitudes. We address the speculation that the present episode of dipole moment decrease is a precursor to the next geomagnetic polarity reversal. The paleomagnetic record contains a broad spectrum of dipole moment fluctuations with polarity reversals typically occurring during dipole moment lows. However, the dipole moment is stronger today than its long time average, indicating that polarity reversal is not likely unless the current episode of moment decrease continues for a thousand years or more.

  18. Lepton dipole moments

    CERN Document Server

    Marciano, William J

    2010-01-01

    This book provides a self-contained description of the measurements of the magnetic dipole moments of the electron and muon, along with a discussion of the measurements of the fine structure constant, and the theory associated with magnetic and electric dipole moments. Also included are the searches for a permanent electric dipole moment of the electron, muon, neutron and atomic nuclei. The related topic of the transition moment for lepton flavor violating processes, such as neutrinoless muon or tauon decays, and the search for such processes are included as well. The papers, written by many o

  19. Dislocated Worker Project.

    Science.gov (United States)

    1988

    Due to the severe economic decline in the automobile manufacturing industry in southeastern Michigan, a Dislocated Workers Program has been developed through the partnership of the Flint Area Chamber of Commerce, three community colleges, the National Center for Research in Vocational Education, the Michigan State Department of Education, the…

  20. Smectic meniscus and dislocations

    International Nuclear Information System (INIS)

    Geminard, J.C.; Oswald, P.; Holyst, R.

    1998-01-01

    In ordinary liquids the size of a meniscus and its shape is set by a competition between surface tension and gravity. The thermodynamical process of its creation can be reversible. On the contrary, in smectic liquid crystals the formation of the meniscus is always an irreversible thermodynamic process since it involves the creation of dislocations (therefore it involves friction). Also the meniscus is usually small in experiments with smectics in comparison to the capillary length and therefore the gravity does not play any role in determining the meniscus shape. Here we discuss the relation between dislocations and meniscus in smectics. The theoretical predictions are supported by a recent experiment performed on freely suspended films of smectic liquid crystals. In this experiment the measurement of the meniscus radius of curvature gives the pressure difference, Δp, according to the Laplace law. From the measurements of the growth dynamics of a dislocation loop (governed by Δp) we find the line tension (∼8 x 10 -8 dyn) and the mobility of an elementary edge dislocation (∼4 x 10 - 7 cm 2 s/g). (author)

  1. Dislocated Shoulder: Symptoms and Causes

    Science.gov (United States)

    ... caused by: Sports injuries. Shoulder dislocation is a common injury in contact sports, such as football and hockey, and in sports that may involve falls, such as downhill skiing, gymnastics and volleyball. ... is a common source of dislocation. Falls. You may dislocate your ...

  2. Energetics of dislocation transformations in hcp metals

    International Nuclear Information System (INIS)

    Wu, Zhaoxuan; Yin, Binglun; Curtin, W.A.

    2016-01-01

    Dislocation core structures of hcp metals are highly complex and differ significantly among the hcp family. Some dislocations undergo unconventional transformations that have significant effects on the material plastic flow. Here, the energetics of dislocation dissociations are analyzed in a general anisotropic linear elastic theory framework for transformations in which changes in the partial Burgers vectors are small. Quantitative analyses on various transformations are made using DFT-computed stacking fault energies and partial Burgers vectors. Specifically, possible transformations of the mixed, edge, and screw 〈c+a〉 and screw 〈a〉 dislocations in 6 hcp metals (Mg, Ti, Zr, Re, Zn, Cd) are studied. Climb dissociation of mixed or edge 〈c+a〉 dislocations to the Basal plane is energetically favorable in all 6 metals and thus only limited by thermal activation. The 〈c+a〉 screw dislocation is energetically preferable on Pyramidal I for Ti, Zr, and Re, and on Pyramidal II for Zn and Cd. In Mg, the energy difference between screw 〈c+a〉 on Pyramidal I and II planes is small, suggesting relatively easy cross-slip. For the screw 〈a〉, Basal dissociation is energetically favorable in Mg, Re, Zn and Cd, while Prism dissociation is strongly favorable in Ti and Zr. Only Ti, Zr and Re show a metastable state for dissociation on the Prism plane, and the energy difference between screw 〈a〉 on the Prism and Pyramidal I planes is relatively small in all systems, suggesting relatively easy cross-slip of 〈a〉 in Ti and Zr. The elastic analysis thus provides a single framework able to capture the controlling energetics for different dissociations and slip systems in hcp metals. When the calculated energy differences are very small, the results point to the need for detailed modeling of the atomistic core structure. Moreover, the analyses rationalize broad experimental observations on dominant slip systems and dislocation behaviours, and provide

  3. Some dipole shower studies

    Science.gov (United States)

    Cabouat, Baptiste; Sjöstrand, Torbjörn

    2018-03-01

    Parton showers have become a standard component in the description of high-energy collisions. Nowadays most final-state ones are of the dipole character, wherein a pair of partons branches into three, with energy and momentum preserved inside this subsystem. For initial-state showers a dipole picture is also possible and commonly used, but the older global-recoil strategy remains a valid alternative, wherein larger groups of partons share the energy-momentum preservation task. In this article we introduce and implement a dipole picture also for initial-state radiation in Pythia, and compare with the existing global-recoil one, and with data. For the case of Deeply Inelastic Scattering we can directly compare with matrix element expressions and show that the dipole picture gives a very good description over the whole phase space, at least for the first branching.

  4. Particle electric dipole moments

    CERN Document Server

    Pendlebury, J M

    2000-01-01

    Measurements of particle electric dipole moments (EDMs) continue to put powerful constraints on theories of T-symmetry and CP-symmetry violation, which form currently one of the most prominent fields in particle physics. EDM measurements have been concentrated on neutral systems such as the neutron and atoms and molecules. These measurements allow one to deduce, in turn, the electric dipole moments of the fundamental fermions, that is, the lighter leptons and quarks and also those of some heavy nuclei.

  5. Dynamics of nonstationary dipole vortices

    DEFF Research Database (Denmark)

    Hesthaven, J.S.; Lynov, Jens-Peter; Nycander, J.

    1993-01-01

    The dynamics of tilted dipole vortices in the equivalent barotropic vorticity (or Hasegawa-Mima) equation is studied. A recent theory is compared with numerical simulations and found to describe the short time behavior of dipole vortices well. In the long time limit the dipoles are found to eithe...... disintegrate or relax toward a steady eastward propagating dipole vortex. This relaxation is a consequence of nonviscous enstrophy loss by the dipole vortex....

  6. Tailoring Superconductivity with Quantum Dislocations.

    Science.gov (United States)

    Li, Mingda; Song, Qichen; Liu, Te-Huan; Meroueh, Laureen; Mahan, Gerald D; Dresselhaus, Mildred S; Chen, Gang

    2017-08-09

    Despite the established knowledge that crystal dislocations can affect a material's superconducting properties, the exact mechanism of the electron-dislocation interaction in a dislocated superconductor has long been missing. Being a type of defect, dislocations are expected to decrease a material's superconducting transition temperature (T c ) by breaking the coherence. Yet experimentally, even in isotropic type I superconductors, dislocations can either decrease, increase, or have little influence on T c . These experimental findings have yet to be understood. Although the anisotropic pairing in dirty superconductors has explained impurity-induced T c reduction, no quantitative agreement has been reached in the case a dislocation given its complexity. In this study, by generalizing the one-dimensional quantized dislocation field to three dimensions, we reveal that there are indeed two distinct types of electron-dislocation interactions. Besides the usual electron-dislocation potential scattering, there is another interaction driving an effective attraction between electrons that is caused by dislons, which are quantized modes of a dislocation. The role of dislocations to superconductivity is thus clarified as the competition between the classical and quantum effects, showing excellent agreement with existing experimental data. In particular, the existence of both classical and quantum effects provides a plausible explanation for the illusive origin of dislocation-induced superconductivity in semiconducting PbS/PbTe superlattice nanostructures. A quantitative criterion has been derived, in which a dislocated superconductor with low elastic moduli and small electron effective mass and in a confined environment is inclined to enhance T c . This provides a new pathway for engineering a material's superconducting properties by using dislocations as an additional degree of freedom.

  7. Neglected isolated scaphoid dislocation

    Directory of Open Access Journals (Sweden)

    Jong-Ryoon Baek

    2016-01-01

    Full Text Available The authors present a case of isolated scaphoid dislocation in a 40-year-old male that was undiagnosed for 2 months. The patient was treated by open reduction, Kirschner wire fixation, interosseous ligament repair using a suture anchor and Blatt's dorsal capsulodesis. At 6 years followup, his radiographs of wrist showed a normal carpal alignment with a scapholunate gap of 3 mm and no evidence of avascular necrosis (AVN of the scaphoid.

  8. Atomistically-informed dislocation dynamics in FCC crystals

    International Nuclear Information System (INIS)

    Martinez, E.; Marian, J.; Arsenlis, A.; Victoria, M.; Martinez, E.; Victoria, M.; Perlado, J.M.

    2008-01-01

    Full text of publication follows. We will present a nodal dislocation dynamics (DD) model to simulate plastic processes in fcc crystals. The model explicitly accounts for all slip systems and Burgers vectors observed in fcc systems, including stacking faults and partial dislocations. We derive simple conservation rules that describe all partial dislocation interactions rigorously and allow us to model and quantify cross-slip processes, the structure and strength of dislocation junctions, and the formation of fcc-specific structures such as stacking fault tetrahedra. The DD framework is built upon isotropic non-singular linear elasticity, and supports itself on information transmitted from the atomistic scale. In this fashion, connection between the meso and micro scales is attained self-consistently with core parameters fitted to atomistic data. We perform a series of targeted simulations to demonstrate the capabilities of the model, including dislocation reactions and dissociations and dislocation junction strength. Additionally we map the four-dimensional stress space relevant for cross-slip and relate our fundings to the plastic behaviour of' monocrystalline fcc metals. (authors)

  9. Dechanneling by dislocation loops

    International Nuclear Information System (INIS)

    Chalant, Gerard.

    1976-09-01

    Ion implantation always induces the creation of dislocation loops. When the damage profile is determined by a backscattering technique, the dechanneling by these loops is implicitely at the origin of these measurements. The dechanneling of alpha particles by dislocation loops produced by the coalescence of quenched-in vacancies in aluminium is studied. The dechanneling and the concentration of loops were determined simultaneously. The dechanneling width around dislocation was found equal to lambda=6A, both for perfect and imperfect loops having a mean diameter d=250A. In the latter case, a dechanneling probability chi=0.34 was determined for the stacking fault, in good agreement with previous determination in gold. A general formula is proposed which takes into account the variation of lambda with the curvature (or the diameter d) of the loops. Finally, by a series of isothermal anneals, the self-diffusion energy ΔH of aluminium was measured. The value obtained ΔH=1.32+-0.10eV is in good agreement with the values obtained by other methods [fr

  10. Dipole-dipole dispersion interactions between neutrons

    OpenAIRE

    Babb, James F.; Higa, Renato; Hussein, Mahir S.

    2016-01-01

    We investigate the long-range interactions between two neutrons utilizing recent data on the neutron static and dynamic electric and magnetic dipole polarizabilities. The resulting long-range potentials are used to make quantitative comparisons between the collisions of a neutron with a neutron and a neutron with a proton. We also assess the importance of the first pion production threshold and first excited state of the nucleon, the $\\Delta$-resonance ($J^{\\pi}$ = + 3/2, I = 3/2). We found b...

  11. Core structure, dislocation energy and Peierls stress for 1/3112-bar 0 edge dislocations with (0001) and {11-bar 00} slip planes in α-Zr

    International Nuclear Information System (INIS)

    Voskoboinikov, R.E.; Osetsky, Yu.N.; Bacon, D.J.

    2005-01-01

    Atomic-scale simulations of edge dislocations of the 1/3112-bar 0(0001) and 1/3112-bar 0{11-bar 00} slip systems have been carried out using a Finnis-Sinclair-type interatomic potential for α-zirconium. The distribution of atomic displacements in the dislocation core shows that in this model the edge dislocation in the basal plane dissociates into two Shockley partials whereas the dislocation in the prism plane remains undissociated. The effective core radius and core energy are estimated, and dislocation response to increasing applied shear strain is investigated. The core properties and the critical stress for dislocation glide (Peierls stress) depend sensitively on whether the core extends or not

  12. Dipoles at rest

    International Nuclear Information System (INIS)

    Griffiths, D.J.

    1992-01-01

    In a world populated by magnetic monopoles (as well as ordinary electric charges), there are two kinds of electric dipoles: those due to separated electric charges, and those due to current loops of magnetic charge. Similarly, there are two kinds of magnetic dipoles: those due to separated magnetic monopoles, and those due to electric current loops. This paper derives the potentials and fields of each of the four dipole species, and calculates the force, torque, energy, momentum, and angular momentum of each type, when placed (at rest) in a static external field (which may itself be produced by electric charges and currents, magnetic charges and currents, or all of these). Some implications and applications of the various results are discussed

  13. Dislocation Line Tensions in the Noble Metals, the Alkali Metals and beta-Brass

    Energy Technology Data Exchange (ETDEWEB)

    Pettersson, B; Malen, K

    1971-06-15

    The line tension for a straight partial dislocation which can produce the necessary slip for a martensitic phase transformation of the bcc-fcc or bcc-hcp type has been calculated in ordered 6-brass and in Li, Na and K. Also the line tension for a Shockley partial dislocation in Cu, Ag and Au has been calculated. Negative line tension is found for certain dislocation directions, and the possible influence of this on the stability of a stacking fault bounded by these partials is discussed

  14. Behavior of misfit dislocations in semipolar InGaN/GaN grown by MOVPE

    Energy Technology Data Exchange (ETDEWEB)

    Kuwahara, Takaaki [Department of Applied Science for Electronics and Materials, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan); Kuwano, Noriyuki [Department of Applied Science for Electronics and Materials, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan); Art, Science and Technology Center for Cooperative Research, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan); Kurisu, Akihiko; Okada, Narihito; Tadatomo, Kazuyuki [Graduate School of Science and Engineering, Yamaguchi University, Ube, Yamaguchi 755-8611 (Japan)

    2012-03-15

    A microstructure in an InGaN/GaN layer grown at the semipolar direction was observed in detail by means of transmission electron microscopy (TEM) in order to analyze the behaviour of dislocations. A (11 anti 22) GaN layer was first deposited on a maskless r (1 anti 102)-plane patterned-substrate, and then an In{sub x} Ga{sub 1-x}N (x =0.10, 0.24) was overgrown to be about 1 {mu}m in thickness. Dislocations near the interface of InGaN/GaN are classified into several types: 1 Threading dislocations lying on (0001). 2. Misfit dislocations lying on the interface of InGaN/GaN. 3. Dislocations along [1 anti 100] at a certain distance from the interface. 4. Dislocations newly formed at the interface and developing along [11 anti 20] on (0001). 5. Partial dislocations accompanied with a stacking fault on (0001). It was found that the misfit dislocations are arrayed in pairs at the direction along [1 anti 100] on the interface of (11 anti 22). Burgers vector of the misfit dislocations was found to be B = <2 anti 1 anti 13>/3. In case of B = [ anti 1 anti 123]/3, they are edge dislocations. The densities of dislocations and stacking faults increase with the In-content in InGaN. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Automating dipole subtraction

    International Nuclear Information System (INIS)

    Hasegawa, K.; Moch, S.; Uwer, P.

    2008-07-01

    We report on automating the Catani-Seymour dipole subtraction which is a general procedure to treat infrared divergences in real emission processes at next-to-leading order in QCD. The automatization rests on three essential steps: the creation of the dipole terms, the calculation of the color linked squared Born matrix elements, and the evaluation of different helicity amplitudes. The routines have been tested for a number of complex processes, such as the real emission process gg→t anti tggg. (orig.)

  16. Automating dipole subtraction

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, K.; Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Uwer, P. [Karlsruhe Univ. (T.H.) (Germany). Inst. fuer Theoretische Teilchenphysik

    2008-07-15

    We report on automating the Catani-Seymour dipole subtraction which is a general procedure to treat infrared divergences in real emission processes at next-to-leading order in QCD. The automatization rests on three essential steps: the creation of the dipole terms, the calculation of the color linked squared Born matrix elements, and the evaluation of different helicity amplitudes. The routines have been tested for a number of complex processes, such as the real emission process gg{yields}t anti tggg. (orig.)

  17. Automatic dipole subtraction

    International Nuclear Information System (INIS)

    Hasegawa, K.

    2008-01-01

    The Catani-Seymour dipole subtraction is a general procedure to treat infrared divergences in real emission processes at next-to-leading order in QCD. We automatized the procedure in a computer code. The code is useful especially for the processes with many parton legs. In this talk, we first explain the algorithm of the dipole subtraction and the whole structure of our code. After that we show the results for some processes where the infrared divergences of real emission processes are subtracted. (author)

  18. Dipole-dipole van der Waals interaction in alkali halides

    International Nuclear Information System (INIS)

    Thakur, B.N.; Thakur, K.P.

    1978-01-01

    Values of van der Waals dipole-dipole constants and interaction energetics of alkali halides are reported using the recent data. The values obtained are somewhat larger than those of earlier workers. (orig.) [de

  19. Motion of 1/3<111> dislocations on Σ3 (112) twin boundaries in nanotwinned copper

    Energy Technology Data Exchange (ETDEWEB)

    Lu, N.; Du, K., E-mail: kuidu@imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Beijing National Center for Electron Microscopy, Tsinghua University, Beijing 100084 (China); Lu, L.; Ye, H. Q. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2014-01-14

    The atomic structure of Σ3 (112) ITBs in nanotwinned Cu is investigated by using aberration-corrected high resolution transmission electron microscopy (HRTEM) and in situ HRTEM observations. The Σ3 (112) ITBs are consisted of periodically repeated three partial dislocations. The in situ HRTEM results show that 1/3[111] partial dislocation moves on the Σ3 (112) incoherent twin boundary (ITB), which was accompanied by a migration of the ITB. A dislocation reaction mechanism is proposed for the motion of 1/3[111] Frank partial dislocation, in which the 1/3[111] partial dislocation exchanges its position with twin boundary dislocations in sequence. In this way, the 1/3[111] dislocation can move on the incoherent twin boundary in metals with low stacking fault energy. Meanwhile, the ITB will migrate in its normal direction accordingly. These results provide insight into the reaction mechanism of 1/3[111] dislocations and ITBs and the associated migration of ITBs.

  20. One-dimensional random walk of nanosized liquid Pb inclusions on dislocations in Al

    DEFF Research Database (Denmark)

    Johnson, E.; Levinsen, M.T.; Steenstrup, S.

    2004-01-01

    to and perpendicular to the dislocations respectively. Movements parallel to the dislocation lines display properties of partially confined one-dimensional random walks where smaller inclusions can be seen to move over distances that are many times their own sizes. In contrast, the trajectories perpendicular...

  1. Dipole-dipole dispersion interactions between neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Babb, James F. [Harvard-Smithsonian Center for Astrophysics, ITAMP, Cambridge, MA (United States); Higa, Renato [Universidade de Sao Paulo, Instituto de Fisica, Sao Paulo (Brazil); Hussein, Mahir S. [Universidade de Sao Paulo, Instituto de Fisica, Sao Paulo (Brazil); Universidade de Sao Paulo, Instituto de Estudos Avancados, Sao Paulo (Brazil); Departamento de Fisica, Instituto Tecnologico de Aeronautica, CTA, Sao Jose dos Campos (Brazil)

    2017-06-15

    We investigate the long-range interactions between two neutrons utilizing recent data on the neutron static and dynamic electric and magnetic dipole polarizabilities. The resulting long-range potentials are used to make quantitative comparisons between the collisions of a neutron with a neutron and a neutron with a proton. We also assess the importance of the first pion production threshold and first excited state of the nucleon, the Δ-resonance (J{sup π} = +3/2, I = 3/2). We found both dynamical effects to be quite relevant for distances r between ∝ 50 fm up to ∝ 10{sup 3} fm in the nn system, the neutron-wall system and in the wall-neutron-wall system, reaching the expected asymptotic limit beyond that. Relevance of our findings to the confinement of ultra cold neutrons inside bottles is discussed. (orig.)

  2. Dipole-dipole interaction of dust grains in plasmas

    International Nuclear Information System (INIS)

    Tskhakaya, D.D.; Shukla, P.K.

    2005-01-01

    Complete screening of the negative dust grain charge by a cloud of trapped ions in plasmas is investigated. In the external electric field, the compound dust particle - 'dust grain + ion cloud' acquires a dipole moment due to displacement of the centers of positive and negative charges in the opposite directions. By analogy to the Van der Waals potential, the dipole-dipole interaction of the compound dust particles can have an attractive behavior. It is shown that the dipole-dipole attractive force can exceed the shadowing force that is connected with the reciprocal interception of ions by the neighboring dust grains

  3. Edge dislocations as sinks for sub-nanometric radiation induced defects in α-iron

    Science.gov (United States)

    Anento, N.; Malerba, L.; Serra, A.

    2018-01-01

    The role of edge dislocations as sinks for small radiation induced defects in bcc-Fe is investigated by means of atomistic computer simulation. In this work we investigate by Molecular Statics (T = 0K) the interaction between an immobile dislocation line and defect clusters of small sizes invisible experimentally. The study highlights in particular the anisotropy of the interaction and distinguishes between absorbed and trapped defects. When the considered defect intersects the dislocation glide plane and the distance from the dislocation line to the defect is on the range between 2 nm and 4 nm, either total or partial absorption of the cluster takes place leading to the formation of jogs. Residual defects produced during partial absorption pin the dislocation. By the calculation of stress-strain curves we have assessed the strength of those residues as obstacles for the motion of the dislocation, which is reflected on the unpinning stresses and the binding energies obtained. When the defect is outside this range, but on planes close to the dislocation glide plane, instead of absorption we have observed a capture process. Finally, with a view to introducing explicitly in kinetic Monte Carlo models a sink with the shape of a dislocation line, we have summarized our findings on a table presenting the most relevant parameters, which define the interaction of the dislocation with the defects considered.

  4. Traumatic hip dislocations in children

    International Nuclear Information System (INIS)

    Minhas, M.S.

    2010-01-01

    Objectives: To evaluate clinical features, treatment and relationship to the time period between dislocation, reduction and early complications of traumatic dislocation of hip in children. Methods: Case series conducted at Jinnah Post Graduate Medical Centre Karachi from July 2005 to August 2009. Children with traumatic hip dislocation up to fifteen years of age who presented in last four years were included in this study. Their clinical information, etiology, associated injuries, duration, method of reduction and early complications are evaluated through emergency room proforma and indoor record. Follow up of patient was updated in outpatient department. Results: We had eight patients, six boys and two girls. Youngest 2.4 years and eldest was 12 years with mean age of 6.2 +- 3.8 years. All presented with posterior hip dislocation. Etiology was road traffic accident in two and history of fall in remaining six patients. Average duration of time between dislocation and reduction was 19 hours range 3-72 hours. Dislocated hips were reduced under General Anaesthesia in two patients and under sedation analgesia in six patients. No complications were noted in eight cases with mean 18.75 +- 13.23 months follows up. Conclusion: Traumatic hip dislocation in children is not rare. Slight trauma causes dislocation in younger age and immediate closed reduction and Immobilization reduces complications. (author

  5. Atomic-scale structure of dislocations revealed by scanning tunneling microscopy and molecular dynamics

    DEFF Research Database (Denmark)

    Christiansen, Jesper; Morgenstern, K.; Schiøtz, Jakob

    2002-01-01

    The intersection between dislocations and a Ag(111) surface has been studied using an interplay of scanning tunneling microscopy (STM) and molecular dynamics. Whereas the STM provides atomically resolved information about the surface structure and Burgers vectors of the dislocations, the simulati......The intersection between dislocations and a Ag(111) surface has been studied using an interplay of scanning tunneling microscopy (STM) and molecular dynamics. Whereas the STM provides atomically resolved information about the surface structure and Burgers vectors of the dislocations......, the simulations can be used to determine dislocation structure and orientation in the near-surface region. In a similar way, the subsurface structure of other extended defects can be studied. The simulations show dislocations to reorient the partials in the surface region leading to an increased splitting width...

  6. Diffusion along and around dislocations; Diffusion le long et autour des dislocations

    Energy Technology Data Exchange (ETDEWEB)

    Brebec, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    We have gathered together in this text some solutions for Fick's equations applicable to diffusion in dislocations. The problems is fairly similar to that of grain boundaries but in this case a further difficulty arises, purely mathematical in fact, due to the supposedly cylindrical shape of the perturbed region around a dislocation. It follows that Fick's equation is used in the form: {partial_derivative}C/{partial_derivative}t=D[{partial_derivative}{sup 2}C/{partial_derivative}r{sup 2}+1/r{partial_derivative}C/{partial_derivative} r + {partial_derivative}{sup 2}C/{partial_derivative}z{sup 2}] in order to express simply the limiting conditions and so that the solution takes into account the symmetry of revolution of the system. This very much complicates the final form of the results. We give here as an illustration a solution obtained using the same hypotheses and making the same approximations as those employed by WHIPPLE for his grain boundary work. Unfortunately the final form is not suitable for a numerical calculation. By making grosser approximations, such a those used by FISHER, it is possible to determine the parameter D/(a{sup 2}D'); the same result as for grain boundary is found i.e that the logarithm of the mean concentration varies linearly with penetration, the slope of this straight line is proportional to {radical}(D/(a{sup 2}D')) Finally we give the exact solution for a platelet of finite thickness assuming that the diffusion in the defect less crystal is negligible and that the surface diffusion is infinitely fast. This is the problem dealt with by HENDRIGKSON and MACHLIN. We arrive at conclusions different to those obtained by these two authors. (author) [French] Nous avons groupe dans ce texte quelques solutions des equations de Fick applicables a la diffusion dans les dislocations. Le probleme est assez analogue a celui des joints de grains mais il s'introduit ici une difficulte supplementaire, d'ailleurs purement mathematique, due au fait de

  7. Dissecting an LHC dipole

    CERN Multimedia

    2004-01-01

    The cold mass of a 15-metre main dipole magnet has some fifteen different components. All the main components are manufactured under CERN's direct responsibility. Four of them transit through CERN before being shipped to the dipole assembly contractors, namely the cable, which constitutes the magnet's superconducting core (see Bulletin 14/2004), the beam screens, the heat exchanger tubes and the cold bore beam tubes. The two latter components transit via Building 927 where they undergo part of the production process. The 58-mm diameter heat exchanger tubes will remove heat from the magnets using superfluid helium. The 53-mm diameter cold bore tubes will be placed under vacuum to allow the twin beams to circulate around the LHC.

  8. Giant Primeval Magnetic Dipoles

    Science.gov (United States)

    Thompson, Christopher

    2017-07-01

    Macroscopic magnetic dipoles are considered cosmic dark matter. Permanent magnetism in relativistic field structures can involve some form of superconductivity, one example being current-carrying string loops (“springs”) with vanishing net tension. We derive the cross-section for free classical dipoles to collide, finding it depends weakly on orientation when mutual precession is rapid. The collision rate of “spring” loops with tension { T }˜ {10}-8{c}4/G in galactic halos approaches the measured rate of fast radio bursts (FRBs) if the loops compose most of the dark matter. A large superconducting dipole (LSD) with mass ˜1020 g and size ˜1 mm will form a ˜100 km magnetosphere moving through interstellar plasma. Although hydromagnetic drag is generally weak, it is strong enough to capture some LSDs into long-lived rings orbiting supermassive black holes (SMBHs) that form by the direct collapse of massive gas clouds. Repeated collisions near young SMBHs could dominate the global collision rate, thereby broadening the dipole mass spectrum. Colliding LSDs produce tiny, hot electromagnetic explosions. The accompanying paper shows that these explosions couple effectively to propagating low-frequency electromagnetic modes, with output peaking at 0.01-1 THz. We describe several constraints on, and predictions of, LSDs as cosmic dark matter. The shock formed by an infalling LSD triggers self-sustained thermonuclear burning in a C/O (ONeMg) white dwarf (WD) of mass ≳1 M ⊙ (1.3 M ⊙). The spark is generally located off the center of the WD. The rate of LSD-induced explosions matches the observed rate of Type Ia supernovae.

  9. Experiments with dipole antennas

    International Nuclear Information System (INIS)

    Kraftmakher, Yaakov

    2009-01-01

    Employment of a data-acquisition system for data collection and calculations makes experiments with antennas more convenient and less time consuming. The determined directional patterns of the dipole antennas of different lengths are in reasonable agreement with theory. The enhancement of the signal by using a reflector is demonstrated, and a variant of the Yagi-Uda antenna is explored. The experiments are suitable as laboratory works and classroom demonstrations, and are attractive for student projects.

  10. ALICE dipole and decoration

    CERN Multimedia

    Maximilien Brice

    2004-01-01

    The ALICE cavern receives a painting made specially to mark the 50th anniversary of CERN that is mounted on the L3 solenoid magnet, reused from the LEP experiment that ran from 1989 to 2000. The dipole, which is cooled by demineralised water, will bend the path of muons that leave the huge rectangular solenoid. These muons are heavy electrons that interact less with matter allowing them to be studied at large distances from the interaction point.

  11. Neutrino production of single pions: Dipole description

    International Nuclear Information System (INIS)

    Kopeliovich, B. Z.; Schmidt, Ivan; Siddikov, M.

    2011-01-01

    The light-cone distribution amplitudes for the axial current are derived within the instanton vacuum model, which incorporates nonperturbative effects including spontaneous chiral symmetry breaking. This allows one to extend applicability of the dipole approach, usually used in the perturbative domain, down to Q 2 →0, where the partially conserved axial current imposes a relation between the neutrino-production cross section and the one induced by pions. A dramatic breakdown of the Adler relation for diffractive neutrino production of pions, caused by absorptive corrections, was revealed recently by Kopeliovich et al.. Indeed, comparing with the cross section predicted by the dipole phenomenology at Q 2 →0 on a proton target we confirmed the sizable deviation from the value given by the Adler relation, as was estimated by Kopeliovich et al. within a simplified two-channel model. The dipole approach also confirms that in the black-disk limit, where the absorptive corrections maximize, the diffractive cross section ceases, on the contrary to the expectation based on the partially conserved axial current.

  12. Visualizing dipole radiation

    International Nuclear Information System (INIS)

    Girwidz, Raimund V

    2016-01-01

    The Hertzian dipole is fundamental to the understanding of dipole radiation. It provides basic insights into the genesis of electromagnetic waves and lays the groundwork for an understanding of half-wave antennae and other types. Equations for the electric and magnetic fields of such a dipole can be derived mathematically. However these are very abstract descriptions. Interpreting these equations and understanding travelling electromagnetic waves are highly limited in that sense. Visualizations can be a valuable supplement that vividly present properties of electromagnetic fields and their propagation. The computer simulation presented below provides additional instructive illustrations for university lectures on electrodynamics, broadening the experience well beyond what is possible with abstract equations. This paper refers to a multimedia program for PCs, tablets and smartphones, and introduces and discusses several animated illustrations. Special features of multiple representations and combined illustrations will be used to provide insight into spatial and temporal characteristics of field distributions—which also draw attention to the flow of energy. These visualizations offer additional information, including the relationships between different representations that promote deeper understanding. Finally, some aspects are also illustrated that often remain unclear in lectures. (paper)

  13. Density of bunched threading dislocations in epitaxial GaN layers as determined using X-ray diffraction

    Science.gov (United States)

    Barchuk, M.; Holý, V.; Rafaja, D.

    2018-04-01

    X-ray diffraction is one of the most popular experimental methods employed for determination of dislocation densities, as it can recognize both the strain fields and the local lattice rotations produced by dislocations. The main challenge of the quantitative analysis of the dislocation density is the formulation of a suitable microstructure model, which describes the dislocation arrangement and the effect of the interactions between the strain fields from neighboring dislocations reliably in order to be able to determine the dislocation densities precisely. The aim of this study is to prove the capability of X-ray diffraction and two computational methods, which are frequently used for quantification of the threading dislocation densities from X-ray diffraction measurements, in the special case of partially bunched threading dislocations. The first method is based on the analysis of the dislocation-controlled crystal mosaicity, and the other one on the analysis of diffuse X-ray scattering from threading dislocations. The complementarity of both methods is discussed. Furthermore, it is shown how the complementarity of these methods can be used to improve the results of the quantitative analysis of bunched and thus inhomogeneously distributed threading dislocations and to get a better insight into the dislocation arrangement.

  14. Asymptotic Analysis of a System of Algebraic Equations Arising in Dislocation Theory

    KAUST Repository

    Hall, Cameron L.; Chapman, S. Jonathan; Ockendon, John R.

    2010-01-01

    The system of algebraic equations given by σn j=0, j≠=i sgn(xi-xj )|xi-xj|a = 1, i = 1, 2, ⋯ , n, x0 = 0, appears in dislocation theory in models of dislocation pile-ups. Specifically, the case a = 1 corresponds to the simple situation where n dislocations are piled up against a locked dislocation, while the case a = 3 corresponds to n dislocation dipoles piled up against a locked dipole. We present a general analysis of systems of this type for a > 0 and n large. In the asymptotic limit n→∞, it becomes possible to replace the system of discrete equations with a continuum equation for the particle density. For 0 < a < 2, this takes the form of a singular integral equation, while for a > 2 it is a first-order differential equation. The critical case a = 2 requires special treatment, but, up to corrections of logarithmic order, it also leads to a differential equation. The continuum approximation is valid only for i neither too small nor too close to n. The boundary layers at either end of the pile-up are also analyzed, which requires matching between discrete and continuum approximations to the main problem. © 2010 Society for Industrial and Applied Mathematics.

  15. AutoDipole - Automated generation of dipole subtraction terms

    International Nuclear Information System (INIS)

    Hasegawa, K.; Uwer, P.

    2009-11-01

    We present an automated generation of the subtraction terms for next-to-leading order QCD calculations in the Catani-Seymour dipole formalism. For a given scattering process with n external particles our Mathematica package generates all dipole terms, allowing for bothmassless and massive dipoles. The numerical evaluation of the subtraction terms proceeds with MadGraph, which provides Fortran code for the necessary scattering amplitudes. Checks of the numerical stability are discussed. (orig.)

  16. AutoDipole - Automated generation of dipole subtraction terms

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, K.; Uwer, P. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2009-11-15

    We present an automated generation of the subtraction terms for next-to-leading order QCD calculations in the Catani-Seymour dipole formalism. For a given scattering process with n external particles our Mathematica package generates all dipole terms, allowing for bothmassless and massive dipoles. The numerical evaluation of the subtraction terms proceeds with MadGraph, which provides Fortran code for the necessary scattering amplitudes. Checks of the numerical stability are discussed. (orig.)

  17. Core structure of screw dislocations in Fe from first-principles; Simulation ab initio des coeurs de dislocation vis dans le fer

    Energy Technology Data Exchange (ETDEWEB)

    Ventelon, L

    2008-11-15

    The various methods appropriate for the simulation of dislocations within first-principles calculations have been set up, improved and compared between them. They have been applied to study screw dislocations in body-centered cubic iron using the SIESTA code. A non-degenerate core structure is obtained; its detailed analysis reveals a dilatation effect. Taking it into account in an anisotropic elasticity model, allows explaining the cell-size dependence of the energetics, obtained within the dipole approach. The Peierls potential obtained in ab initio suggests that the metastable core configuration at halfway position in the Peierls barrier, predicted by empirical potential, does not exist. We show how to construct tri-periodic cells optimized to study kinked dislocations. Using empirical potential, we demonstrate the feasibility of ab initio calculations of Peierls stress and kink formation. (author)

  18. Microscopically derived free energy of dislocations

    NARCIS (Netherlands)

    Kooiman, M.; Hütter, M.; Geers, M.G.D.

    2015-01-01

    The dynamics of large amounts of dislocations is the governing mechanism in metal plasticity. The free energy of a continuous dislocation density profile plays a crucial role in the description of the dynamics of dislocations, as free energy derivatives act as the driving forces of dislocation

  19. Discrete dislocation modelling of submicron indentation

    NARCIS (Netherlands)

    Widjaja, A; Van der Giessen, E; Needleman, A

    2005-01-01

    Indentation of a planar single crystal by a circular rigid indenter is analyzed using discrete dislocation plasticity. The crystal has three slip systems and is initially dislocation-free, but edge dislocations can nucleate from point sources inside the crystal. The lattice resistance to dislocation

  20. Neutron Electric Dipole Moment

    International Nuclear Information System (INIS)

    Mischke, R.E.

    2003-01-01

    The status of experiments to measure the electric dipole moment of the neutron is presented and the planned experiment at Los Alamos is described. The goal of this experiment is an improvement in sensitivity of a factor of 50 to 100 over the current limit. It has the potential to reveal new sources of T and CP violation and to challenge calculations that propose extensions to the Standard Model. The experiment employs several advances in technique to reach its goals and the feasibility of meeting these technical challenges is currently under study

  1. On the annealing of the EPR dislocation signal in silicon

    International Nuclear Information System (INIS)

    Zolotukhin, M.N.; Kveder, V.V.; Osip'yan, Yu.A.

    1981-01-01

    The annealing kinetics of the (EPR) dislocation signal (D-centers) in silicon is studied. The disappearance of the dislocation EPR signal as a result of annealing is ascribed to rearrangement of the nuclei of the partial dislocations accompanied by pairwise ''closing'' of the broken bonds in the S=0 state. The height of the energy barrier for the rearrangement process is approximately 2 eV. A residual ''nonannealing'' EPR signal is observed in strongly deformed silicon crystals. It resembles an isotropic line with a width approximately 7.5 Oe and a g-factor approximately 2.006. It is suggested that the respective EPR centers (O-centers) are similar to the EPR centers in amorphic silicon [ru

  2. Strengthening mechanisms and dislocation processes in <111> textured nanotwinned copper

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xing [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083 (China); Lu, Cheng, E-mail: chenglu@uow.edu.au [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Tieu, Anh Kiet; Pei, Linqing; Zhang, Liang; Cheng, Kuiyu [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522 (Australia); Huang, Minghui [State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083 (China)

    2016-10-31

    We use molecular dynamics simulations to elucidate the deformation mechanisms of <111> textured nanotwinned materials under tensile loading parallel to the twin boundary (TB). Our simulations reveal that the tensile strength of nanotwinned Cu increases monotonically as the twin spacing decreases. The strengthening effect mainly results from TB restricting the transmission of dislocations across the TB. Throughout the simulations the transmissions of dislocations across the TBs dominate the plastic deformation. Both direct and indirect transmissions are identified at atomic level. Direct transmission involves either successive transmission of the leading and trailing partials as in the Fleischer cross-slip model or absorption and desorption of the extended dislocation as in the Friedel-Escaig cross-slip mechanism. In contrast, indirect transmission involves the formation of special superjogs. The persistent slip transfer leaves zigzag slip traces on the cross-sectional view and the inhomogeneous deformation leads to the formation of intersecting slip bands on the plane view.

  3. Neglected locked vertical patellar dislocation

    Science.gov (United States)

    Gupta, Rakesh Kumar; Gupta, Vinay; Sangwan, Sukhbir Singh; Kamboj, Pradeep

    2012-01-01

    Patellar dislocations occurring about the vertical and horizontal axis are rare and irreducible. The neglected patellar dislocation is still rarer. We describe the clinical presentation and management of a case of neglected vertical patellar dislocation in a 6 year-old boy who sustained an external rotational strain with a laterally directed force to his knee. Initially the diagnosis was missed and 2 months later open reduction was done. The increased tension generated by the rotation of the lateral extensor retinaculum kept the patella locked in the lateral gutter even with the knee in full extension. Traumatic patellar dislocation with rotation around a vertical axis has been described earlier, but no such neglected case has been reported to the best of our knowledge. PMID:23162154

  4. Neglected locked vertical patellar dislocation

    Directory of Open Access Journals (Sweden)

    Rakesh Kumar Gupta

    2012-01-01

    Full Text Available Patellar dislocations occurring about the vertical and horizontal axis are rare and irreducible. The neglected patellar dislocation is still rarer. We describe the clinical presentation and management of a case of neglected vertical patellar dislocation in a 6 year-old boy who sustained an external rotational strain with a laterally directed force to his knee. Initially the diagnosis was missed and 2 months later open reduction was done. The increased tension generated by the rotation of the lateral extensor retinaculum kept the patella locked in the lateral gutter even with the knee in full extension. Traumatic patellar dislocation with rotation around a vertical axis has been described earlier, but no such neglected case has been reported to the best of our knowledge.

  5. Trans-triquetral Perilunate fracture dislocation

    OpenAIRE

    John-Henry Rhind; Abhinav Gulihar; Andrew Smith

    2018-01-01

    Perilunate dislocations and perilunate fracture dislocations are rare and serious injuries. Perilunate dislocations represent less than 10% of all carpal injuries of which 61% represent transcaphoid fractures. Because of their rarity, up to 25% of perilunate dislocations are initially missed on first assessment. We present the case of a 66-year-old-gentleman who sustained an isolated trans-triquetral perilunate fracture dislocation while walking his dog. This was diagnosed in the emergency de...

  6. HRTEM studies of dislocations in cubic BN

    International Nuclear Information System (INIS)

    Nistor, L.C.; Tendeloo, G. van; Dinca, G.

    2004-01-01

    The atomic structure of dislocations in cubic boron nitride has been investigated by high resolution transmission electron microscopy. Most of the perfect dislocations, screw and 60 edge, are dissociated. A 60 dislocation which was undissociated has been analysed. Computer simulation is performed in an attempt to characterise the core structure. Twinning dislocations and dislocations resulting from the intersection of stacking faults are also revealed. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. HRTEM studies of dislocations in cubic BN

    Energy Technology Data Exchange (ETDEWEB)

    Nistor, L.C. [National Institute for Materials Physics, P.O. Box MG-7 Magurele, 077125 Bucharest (Romania); Tendeloo, G. van [University of Antwerp, EMAT, Groenenborgerlaan 171, 2020 Antwerp (Belgium); Dinca, G. [Dacia Synthetic Diamond Factory, Timisoara av. 5, P.O. Box 58-52, 077350 Bucharest (Romania)

    2004-09-01

    The atomic structure of dislocations in cubic boron nitride has been investigated by high resolution transmission electron microscopy. Most of the perfect dislocations, screw and 60 edge, are dissociated. A 60 dislocation which was undissociated has been analysed. Computer simulation is performed in an attempt to characterise the core structure. Twinning dislocations and dislocations resulting from the intersection of stacking faults are also revealed. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Magnetic dipole moment of a moving electric dipole

    OpenAIRE

    Hnizdo, V.

    2012-01-01

    The current density of a moving electric dipole is expressed as the sum of polarization and magnetization currents. The magnetic field due to the latter current is that of a magnetic dipole moment that is consistent with the relativistic transformations of the polarization and magnetization of macroscopic electrodynamics.

  9. Collisional transfer of coherence by electric dipole-dipole interaction

    OpenAIRE

    Gough , W.

    1983-01-01

    An expression is derived for the contribution from dipole-dipole interaction to the intensity of sensitized fluorescence, from the results of a theory by Chiu. Tensor operator methods are used. The degree of polarization is deduced for certain particular cases.

  10. Magnetic field of a dipole and the dipole-dipole interaction

    International Nuclear Information System (INIS)

    Kraftmakher, Yaakov

    2007-01-01

    With a data-acquisition system and sensors commercially available, it is easy to determine magnetic fields produced by permanent magnets and to study the dipole-dipole interaction for different separations and angular positions of the magnets. For sufficiently large distances, the results confirm the 1/R 3 law for the magnetic field and the 1/R 4 law for the interaction force between two dipoles, as well as their angular dependences

  11. Induced dipole-dipole coupling between two atoms at a migration resonance

    Science.gov (United States)

    Kaur, Maninder; Mian, Mahmood

    2018-05-01

    Results of numerical simulations for the resonant energy exchange phenomenon called Migration reaction between two cold Rydberg atoms are presented. The effect of spatial interatomic distance on the onset of peculiar coherent mechanism is investigated. Observation of Rabi-like population inversion oscillation at the resonance provides a clear signature of dipole induced exchange of electronic excitations between the atoms. Further we present the results for the dependence of expectation value of the interaction hamiltonian on the interatomic distance, which is responsible for energy exchange process. The results of this observation endorse the range of inter atomic distance within which the excitation exchange process occurs completely or partially. Migration process enhance the Rydberg-Rydberg interaction in the absence of an external field, under the condition of the zero permanent dipole moments. Our next observation sheds light on the fundamental mechanism of induced electric fields initiated by the oscillating dipoles in such energy exchange processes. We explore the dependence of induced electric field on the interatomic distance and angle between the dipoles highlighting the inverse power law dependence and anisotropic property of the field. We put forward an idea to utilise the coherent energy exchange process to build efficient and fast energy transfer channels by incorporating more atoms organised at successive distances with decreasing distance gradient.

  12. Local electric dipole moments: A generalized approach.

    Science.gov (United States)

    Groß, Lynn; Herrmann, Carmen

    2016-09-30

    We present an approach for calculating local electric dipole moments for fragments of molecular or supramolecular systems. This is important for understanding chemical gating and solvent effects in nanoelectronics, atomic force microscopy, and intensities in infrared spectroscopy. Owing to the nonzero partial charge of most fragments, "naively" defined local dipole moments are origin-dependent. Inspired by previous work based on Bader's atoms-in-molecules (AIM) partitioning, we derive a definition of fragment dipole moments which achieves origin-independence by relying on internal reference points. Instead of bond critical points (BCPs) as in existing approaches, we use as few reference points as possible, which are located between the fragment and the remainder(s) of the system and may be chosen based on chemical intuition. This allows our approach to be used with AIM implementations that circumvent the calculation of critical points for reasons of computational efficiency, for cases where no BCPs are found due to large interfragment distances, and with local partitioning schemes other than AIM which do not provide BCPs. It is applicable to both covalently and noncovalently bound systems. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  13. Dislocation mediated alignment during metal nanoparticle coalescence

    International Nuclear Information System (INIS)

    Lange, A.P.; Samanta, A.; Majidi, H.; Mahajan, S.; Ging, J.; Olson, T.Y.; Benthem, K. van; Elhadj, S.

    2016-01-01

    Dislocation mediated alignment processes during gold nanoparticle coalescence were studied at low and high temperatures using molecular dynamics simulations and transmission electron microscopy. Particles underwent rigid body rotations immediately following attachment in both low temperature (500 K) simulated coalescence events and low temperature (∼315 K) transmission electron microscopy beam heating experiments. In many low temperature simulations, some degree of misorientation between particles remained after rigid body rotations, which was accommodated by grain boundary dislocation nodes. These dislocations were either sessile and remained at the interface for the duration of the simulation or dissociated and cross-slipped through the adjacent particles, leading to improved co-alignment. Minimal rigid body rotations were observed during or immediately following attachment in high temperature (1100 K) simulations, which is attributed to enhanced diffusion at the particles' interface. However, rotation was eventually induced by {111} slip on planes parallel to the neck groove. These deformation modes led to the formation of single and multi-fold twins whose structures depended on the initial orientation of the particles. The driving force for {111} slip is attributed to high surface stresses near the intersection of low energy {111} facets in the neck region. The details of this twinning process were examined in detail using simulated trajectories, and the results reveal possible mechanisms for the nucleation and propagation of Shockley partials on consecutive planes. Deformation twinning was also observed in-situ using transmission electron microscopy, which resulted in the co-alignment of a set of the particles' {111} planes across their grain boundary and an increase in their dihedral angle. This constitutes the first detailed experimental observation of deformation twinning during nanoparticle coalescence, validating simulation results presented here and

  14. On Closely Coupled Dipoles in a Random Field

    DEFF Research Database (Denmark)

    Andersen, Jørgen Bach; Vincent, L.

    2006-01-01

    Reception of partially correlated fields by two closely coupled electrical dipoles is discussed as a function of load impedances and open-circuit correlations. Two local maxima of the power may be achieved for two different load impedances, but in those cases the output correlations are high...

  15. Work Hardening, Dislocation Structure, and Load Partitioning in Lath Martensite Determined by In Situ Neutron Diffraction Line Profile Analysis

    Science.gov (United States)

    Harjo, Stefanus; Kawasaki, Takuro; Tomota, Yo; Gong, Wu; Aizawa, Kazuya; Tichy, Geza; Shi, Zengmin; Ungár, Tamas

    2017-09-01

    A lath martensite steel containing 0.22 mass pct carbon was analyzed in situ during tensile deformation by high-resolution time-of-flight neutron diffraction to clarify the large work-hardening behavior at the beginning of plastic deformation. The diffraction peaks in plastically deformed states exhibit asymmetries as the reflection of redistributions of the stress and dislocation densities/arrangements in two lath packets: soft packet, where the dislocation glides are favorable, and hard packet, where they are unfavorable. The dislocation density was as high as 1015 m-2 in the as-heat-treated state. During tensile straining, the load and dislocation density became different between the two lath packets. The dislocation character and arrangement varied in the hard packet but hardly changed in the soft packet. In the hard packet, dislocations that were mainly screw-type in the as-heat-treated state became primarily edge-type and rearranged towards a dipole character related to constructing cell walls. The hard packet played an important role in the work hardening in martensite, which could be understood by considering the increase in dislocation density along with the change in dislocation arrangement.

  16. Measuring strain and rotation fields at the dislocation core in graphene

    Science.gov (United States)

    Bonilla, L. L.; Carpio, A.; Gong, C.; Warner, J. H.

    2015-10-01

    Strain fields, dislocations, and defects may be used to control electronic properties of graphene. By using advanced imaging techniques with high-resolution transmission electron microscopes, we have measured the strain and rotation fields about dislocations in monolayer graphene with single-atom sensitivity. These fields differ qualitatively from those given by conventional linear elasticity. However, atom positions calculated from two-dimensional (2D) discrete elasticity and three-dimensional discrete periodized Föppl-von Kármán equations (dpFvKEs) yield fields close to experiments when determined by geometric phase analysis. 2D theories produce symmetric fields whereas those from experiments exhibit asymmetries. Numerical solutions of dpFvKEs provide strain and rotation fields of dislocation dipoles and pairs that also exhibit asymmetries and, compared with experiments, may yield information on out-of-plane displacements of atoms. While discrete theories need to be solved numerically, analytical formulas for strains and rotation about dislocations can be obtained from 2D Mindlin's hyperstress theory. These formulas are very useful for fitting experimental data and provide a template to ascertain the importance of nonlinear and nonplanar effects. Measuring the parameters of this theory, we find two characteristic lengths between three and four times the lattice spacings that control dilatation and rotation about a dislocation. At larger distances from the dislocation core, the elastic fields decay to those of conventional elasticity. Our results may be relevant for strain engineering in graphene and other 2D materials of current interest.

  17. Backfire antennas with dipole elements

    DEFF Research Database (Denmark)

    Nielsen, Erik Dragø; Pontoppidan, Knud

    1970-01-01

    A method is set up for a theoretical investigation of arbitrary backfire antennas based upon dipole structures. The mutual impedance between the dipole elements of the antenna is taken into account, and the field radiated due to a surface wave reflector of finite extent is determined by calculating...

  18. Dipole plasma in molecular crystals

    International Nuclear Information System (INIS)

    Kotel'nikov, Yu.E.; Kochelaev, B.I.

    1976-01-01

    Collective oscillations in a system of electric dipoles of molecular crystals are investigated. It has been proved in the exciton approximation that in an elementary cell of a molecular crystal with one molecule there may exist energy fluctuations of the ''dipole'' plasma, analogous to plasma oscillations in the charged Fermi liquid

  19. Neutron Electric Dipole Moment Experiments

    OpenAIRE

    Peng, Jen-Chieh

    2008-01-01

    The neutron electric dipole moment (EDM) provides unique information on CP violation and physics beyond the Standard Model. We first review the history of experimental searches for neutron electric dipole moment. The status of future neutron EDM experiments, including experiments using ultra-cold neutrons produced in superfluid helium, will then be presented.

  20. Motion of 1/3⟨111⟩ dislocations on Σ3 {112} twin boundaries in nanotwinned copper

    Science.gov (United States)

    Lu, N.; Du, K.; Lu, L.; Ye, H. Q.

    2014-01-01

    The atomic structure of Σ3 {112} ITBs in nanotwinned Cu is investigated by using aberration-corrected high resolution transmission electron microscopy (HRTEM) and in situ HRTEM observations. The Σ3 {112} ITBs are consisted of periodically repeated three partial dislocations. The in situ HRTEM results show that 1/3[111] partial dislocation moves on the Σ3 {112} incoherent twin boundary (ITB), which was accompanied by a migration of the ITB. A dislocation reaction mechanism is proposed for the motion of 1/3[111] Frank partial dislocation, in which the 1/3[111] partial dislocation exchanges its position with twin boundary dislocations in sequence. In this way, the 1/3[111] dislocation can move on the incoherent twin boundary in metals with low stacking fault energy. Meanwhile, the ITB will migrate in its normal direction accordingly. These results provide insight into the reaction mechanism of 1/3[111] dislocations and ITBs and the associated migration of ITBs.

  1. Atomistic simulation of the pinning of edge dislocations in Ni by Ni3Al precipitates

    International Nuclear Information System (INIS)

    Kohler, Christopher; Kizler, Peter; Schmauder, Siegfried

    2005-01-01

    Classical molecular dynamics simulations of the interaction of edge dislocations in Ni with chains of spherical Ni 3 Al precipitates are performed using EAM potentials. The order hardening is investigated at temperature T=0 -bar K by determining the critical resolved shear stresses (CRSSs) for a superdislocation that is dissociated into four partial dislocations. The CRSS is computed as a function of the radius and the distance of the precipitates. It is found that for precipitates with a diameter smaller than the dissociation width of perfect edge dislocation in Ni, the CRSS of the trailing dislocation of the superdislocation is a fraction of about 0.4 of the CRSS of the leading dislocation

  2. Mapping the HISS Dipole

    International Nuclear Information System (INIS)

    McParland, C.; Bieser, F.

    1984-01-01

    The principal component of the Bevalac HISS facility is a large super-conducting 3 Tesla dipole. The facility's need for a large magnetic volume spectrometer resulted in a large gap geometry - a 2 meter pole tip diameter and a 1 meter pole gap. Obviously, the field required detailed mapping for effective use as a spectrometer. The mapping device was designed with several major features in mind. The device would measure field values on a grid which described a closed rectangular solid. The grid would be a regular with the exact measurement intervals adjustable by software. The device would function unattended over the long period of time required to complete a field map. During this time, the progress of the map could be monitored by anyone with access to the HISS VAX computer. Details of the mechanical, electrical, and control design follow

  3. Correction of magnetization sextupole and decapole in a 5 centimeter bore SSC dipole using passive superconductor

    International Nuclear Information System (INIS)

    Green, M.A.

    1991-05-01

    Higher multipoles due to magnetization of the superconductor in four and five centimeter bore Superconducting Super Collider (SSC) superconducting dipole magnets have been observed. The use of passive superconductor to correct out the magnetization sextupole has been demonstrated on two dipoles built by the Lawrence Berkeley Laboratory (LBL). This reports shows how passive correction can be applied to the five centimeter SSC dipoles to remove sextupole and decapole caused by magnetization of the dipole superconductor. Two passive superconductor corrector options will be presented. The change in magnetization sextupole and decapole due to flux creep decay of the superconductor during injection can be partially compensated for using the passive superconductor. 9 refs; 5 figs

  4. Dislocations and other topological oddities

    Science.gov (United States)

    Pieranski, Pawel

    2016-03-01

    We will show that the book Dislocations by Jacques Friedel, published half a century ago, can still be recommended, in agreement with the author's intention, as a textbook ;for research students at University and for students at engineering schools as well as for research engineers;. Indeed, today dislocations are known to occur not only in solid crystals but also in many other systems discovered more recently such as colloidal crystals or liquid crystals having periodic structures. Moreover, the concept of dislocations is an excellent starting point for lectures on topological defects occurring in systems equipped with order parameters resulting from broken symmetries: disclinations in nematic or hexatic liquid crystals, dispirations in chiral smectics or disorientations in lyotropic liquid crystals. The discussion of dislocations in Blue Phases will give us an opportunity to call on mind Sir Charles Frank, friend of Jacques Friedel since his Bristol years, who called these ephemeral mesophases ;topological oddities;. Being made of networks of disclinations, Blue Phases are similar to Twist Grain Boundary (TGB) smectic phases, which are made of networks of screw dislocations and whose existence was predicted by de Gennes in 1972 on the basis of the analogy between smectics and superconductors. We will stress that the book by Jacques Friedel contains seeds of this analogy.

  5. Core structure of screw dislocations in Fe from first-principles

    International Nuclear Information System (INIS)

    Ventelon, L.

    2008-11-01

    The various methods appropriate for the simulation of dislocations within first-principles calculations have been set up, improved and compared between them. They have been applied to study screw dislocations in body-centered cubic iron using the SIESTA code. A non-degenerate core structure is obtained; its detailed analysis reveals a dilatation effect. Taking it into account in an anisotropic elasticity model, allows explaining the cell-size dependence of the energetics, obtained within the dipole approach. The Peierls potential obtained in ab initio suggests that the metastable core configuration at halfway position in the Peierls barrier, predicted by empirical potential, does not exist. We show how to construct tri-periodic cells optimized to study kinked dislocations. Using empirical potential, we demonstrate the feasibility of ab initio calculations of Peierls stress and kink formation. (author)

  6. A continuum theory of edge dislocations

    Science.gov (United States)

    Berdichevsky, V. L.

    2017-09-01

    Continuum theory of dislocation aims to describe the behavior of large ensembles of dislocations. This task is far from completion, and, most likely, does not have a "universal solution", which is applicable to any dislocation ensemble. In this regards it is important to have guiding lines set by benchmark cases, where the transition from a discrete set of dislocations to a continuum description is made rigorously. Two such cases have been considered recently: equilibrium of dislocation walls and screw dislocations in beams. In this paper one more case is studied, equilibrium of a large set of 2D edge dislocations placed randomly in a 2D bounded region. The major characteristic of interest is energy of dislocation ensemble, because it determines the structure of continuum equations. The homogenized energy functional is obtained for the periodic dislocation ensembles with a random contents of the periodic cell. Parameters of the periodic structure can change slowly on distances of order of the size of periodic cells. The energy functional is obtained by the variational-asymptotic method. Equilibrium positions are local minima of energy. It is confirmed the earlier assertion that energy density of the system is the sum of elastic energy of averaged elastic strains and microstructure energy, which is elastic energy of the neutralized dislocation system, i.e. the dislocation system placed in a constant dislocation density field making the averaged dislocation density zero. The computation of energy is reduced to solution of a variational cell problem. This problem is solved analytically. The solution is used to investigate stability of simple dislocation arrays, i.e. arrays with one dislocation in the periodic cell. The relations obtained yield two outcomes: First, there is a state parameter of the system, dislocation polarization; averaged stresses affect only dislocation polarization and cannot change other characteristics of the system. Second, the structure of

  7. Prediction of dislocation boundary characteristics

    DEFF Research Database (Denmark)

    Winther, Grethe

    Plastic deformation of both fcc and bcc metals of medium to high stacking fault energy is known to result in dislocation patterning in the form of cells and extended planar dislocation boundaries. The latter align with specific crystallographic planes, which depend on the crystallographic......) and it is found that to a large extent the dislocations screen each other’s elastic stress fields [3]. The present contribution aims at advancing the previous theoretical analysis of a boundary on a known crystallographic plane to actual prediction of this plane as well as other boundary characteristics....... Crystal plasticity calculations combined with the hypothesis that these boundaries separate domains with local differences in the slip system activity are introduced to address precise prediction of the experimentally observed boundaries. The presentation will focus on two cases from fcc metals...

  8. Relaxation strain measurements in cellular dislocation structures

    International Nuclear Information System (INIS)

    Tsai, C.Y.; Quesnel, D.J.

    1984-01-01

    The conventional picture of what happens during a stress relaxation usually involves imagining the response of a single dislocation to a steadily decreasing stress. The velocity of this dislocation decreases with decreasing stress in such a way that we can measure the stress dependence of the dislocation velocity. Analysis of the data from a different viewpoint enables us to calculate the apparent activation volume for the motion of the dislocation under the assumption of thermally activated glie. Conventional thinking about stress relaxation, however, does not consider the eventual fate of this dislocation. If the stress relaxes to a low enough level, it is clear that the dislocation must stop. This is consistent with the idea that we can determine the stress dependence of the dislocation velocity from relaxation data only for those cases where the dislocation's velocity is allowed to approach zero asymptotically, in short, for those cases where the dislocation never stops. This conflict poses a dilemma for the experimentalist. In real crystals, however, obstacles impede the dislocation's progress so that those dislocations which are stopped at a given stress will probably never resume motion under the influence of the steadily declining stress present during relaxation. Thus one could envision stress relaxation as a process of exhaustion of mobile dislocations, rather than a process of decreasing dislocation velocity. Clearly both points of view have merit and in reality both mechanisms contribute to the phenomena

  9. Irreducible Traumatic Posterior Shoulder Dislocation

    Directory of Open Access Journals (Sweden)

    Blake Collier

    2017-01-01

    Full Text Available History of present illness: A 22-year-old male presented to the Emergency Department complaining of right shoulder pain after a motocross accident. He was traveling at approximately 10 mph around a turn when he lost control and was thrown over the handlebars, landing directly on his right shoulder. On arrival, he was holding his arm in adduction and internal rotation. An area of swelling was noted over his anterior shoulder. He was unable to abduct his shoulder. No humeral gapping was noted. He had normal neuro-vascular status distal to the injury. Significant findings: Radiographs demonstrated posterior displacement of the humeral head on the “Y” view (see white arrow and widening of the glenohumeral joint space on anterior-posterior view (see red arrow. The findings were consistent with posterior dislocation and a Hill-Sachs type deformity. Sedation was performed and reduction was attempted using external rotation, traction counter-traction. An immediate “pop” was felt during the procedure. Post-procedure radiographs revealed a persistent posterior subluxation with interlocking at posterior glenoid. CT revealed posterior dislocation with acute depressed impaction deformity medial to the biceps groove with the humeral head perched on the posterior glenoid, interlocked at reverse Hill-Sachs deformity (see blue arrow. Discussion: Posterior shoulder dislocations are rare and represent only 2% of all shoulder dislocations. Posterior shoulder dislocations are missed on initial diagnosis in more than 60% of cases.1 Posterior shoulder dislocations result from axial loading of the adducted and internally rotated shoulder, violent muscle contractions (resulting from seizures or electrocution, a direct posterior force applied to the anterior shoulder.1 Physical findings include decreased anterior prominence of the humeral head, increased palpable posterior prominence of the humeral head below the acromion, increased palpable prominence of the

  10. Bipolar dislocation of the clavicle

    Directory of Open Access Journals (Sweden)

    Wei Jiang

    2012-01-01

    Full Text Available Bipolar dislocation of the clavicle at acromioclavicular and sternoclavicular joint is an uncommon traumatic injury. The conservative treatments adopted in the past is associated with redislocation dysfunction and deformity. A 41 years old lady with bipolar dislocation of right shoulder is treated surgically by open reduction and internal fixation by oblique T-plate at sternoclavicular joint and Kirschner wire stabilization at acromioclavicular joint. The patient showed satisfactory recovery with full range of motion of the right shoulder and normal muscular strength. The case reported in view of rarity and at 2 years followup.

  11. Simulations of the atomic structure, energetics, and cross slip of screw dislocations in copper

    DEFF Research Database (Denmark)

    Rasmussen, Torben; Jacobsen, Karsten Wedel; Leffers, Torben

    1997-01-01

    Using nanoscale atomistic simulations it has been possible to address the problem of cross slip of a dissociated screw dislocation in an fee metal (Cu) by a method not suffering from the limitations imposed by elasticity theory. The focus has been on different dislocation configurations relevant...... linear-elasticity theory showing recombination or repulsion of the partials near the free surface. Such recombination at the free surface might be important in the context of cross slip because it allows the creation of the above-mentioned energetically favorable constriction alone. In addition we...... to monitor the annihilation process, thereby determining the detailed dislocation reactions during annihilation....

  12. Structure and electronic properties of mixed (a + c) dislocation cores in GaN

    Energy Technology Data Exchange (ETDEWEB)

    Horton, M. K., E-mail: m.horton11@imperial.ac.uk [Department Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Rhode, S. L. [Department Materials Science and Metallurgy, University of Cambridge, Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Moram, M. A. [Department Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Department Materials Science and Metallurgy, University of Cambridge, Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

    2014-08-14

    Classical atomistic models and atomic-resolution scanning transmission electron microscopy studies of GaN films reveal that mixed (a + c)-type dislocations have multiple different core structures, including a dissociated structure consisting of a planar fault on one of the (12{sup ¯}10) planes terminated by two different partial dislocations. Density functional theory calculations show that all cores introduce localized states into the band gap, which affects device performance.

  13. Structure and electronic properties of mixed (a + c) dislocation cores in GaN

    International Nuclear Information System (INIS)

    Horton, M. K.; Rhode, S. L.; Moram, M. A.

    2014-01-01

    Classical atomistic models and atomic-resolution scanning transmission electron microscopy studies of GaN films reveal that mixed (a + c)-type dislocations have multiple different core structures, including a dissociated structure consisting of a planar fault on one of the (12 ¯ 10) planes terminated by two different partial dislocations. Density functional theory calculations show that all cores introduce localized states into the band gap, which affects device performance

  14. The movement of screw dislocations in tungsten

    International Nuclear Information System (INIS)

    Tian Xiaogeng; Woo Chungho

    2004-01-01

    Using Acland potential for tungsten, the movement of 1/2a screw dislocation under shear stress was investigated by molecular dynamics simulation. Equilibrated core structure was obtained by relaxation of screw dislocation with proper boundary conditions. We found that the equilibrium dislocation core has three-fold symmetry and spread out in three direction on {1 1 0} planes. The screw dislocation core could not keep the original shape when the shear stress applied. The dislocation could not move until the shear stress became large enough. The dislocation moved in zigzag when the shear stress neared the Peierls stress. When the shear stress became larger, the dislocation moved in zigzag at the beginning and than moved almost in straight line in [2-bar11] direction. The large shear stress applied, the long distance moved before the dislocation stilled in z-direction and the large velocity in y-direction

  15. LHC Dipoles Accelerate

    CERN Multimedia

    2001-01-01

    Andrezej Siemko (left), Peter Sievers (centre), and Lucio Rossi (right), have the exciting challenge of preparing and testing 2000 magnets for the LHC. The LHC is going to require a lot of powerful magnets by the time it begins operation in 2006. More specifically, it is going to need 130 special magnets, 400 quadrupoles, and a whopping 1250 dipoles! Preparing and testing these magnets for the conditions they will encounter in the LHC is not an easy task. But evaluation of the most recently received magnet, from the German company Noell, is showing that while the monumental task of receiving and testing nearly 2000 magnets is going to be exhausting, the goals are definitely attainable. At the moment and over the next year, pre-series magnets (the magnets that CERN uses to fine tune performance) are arriving slowly (90 in total will arrive), but by 2003 the rate of series magnet arrival will accelerate to 9 per week, that's over 450 in a single year! And working with these magnets when they arrive is tough. ...

  16. Morphology of single Shockley-type stacking faults generated by recombination enhanced dislocation glide in 4H-SiC

    Science.gov (United States)

    Matsuhata, Hirofumi; Sekiguchi, Takashi

    2018-04-01

    Morphology of single Shockley-type stacking faults (SFs) generated by recombination enhanced dislocation glide (REDG) in 4H-SiC are discussed and analysed. A complete set of the 12 different dissociated states of basal-plane dislocation loops is obtained using the crystallographic space group operations. From this set, six different double rhombic-shaped SFs are derived. These tables indicate the rules that connect shapes of SFs with the locations of partial dislocations having different core structures, the positions of slip planes in a unit cell, and the Burgers vectors of partial dislocations. We applied these tables for the analysis of SFs generated by the REDG effect reported in the past articles. Shapes, growing process of SFs and perfect dislocations for origins of SFs were well analysed systematically.

  17. Posterior Dislocation of the Hip

    African Journals Online (AJOL)

    than 24 hours, and 13 more than 48 hours after injury. (Table II). TABLE If. RESULTS PLOITED AGAINST DELAY IN. REDUCTION OF THE DISLOCATION. Time from injury. (h). Excellent. Poor and fair. Total. 48. 7. 6. 13. Reduction, as a rule, was effected under general anaes-.

  18. Scattering of phonons by dislocations

    International Nuclear Information System (INIS)

    Anderson, A.C.

    1979-01-01

    By 1950, an explicit effort had been launched to use lattice thermal conductivity measurements in the investigation of defect structures in solids. This technique has been highly successful, especially when combined with the measurements of other properties such as optical absorption. One exception has been the study of dislocations. Although dislocations have a profound effect on the phonon thermal conductivity, the mechanisms of the phonon-dislocation interaction are poorly understood. The most basic questions are still debated in the literature. It therefore is pointless to attempt a quantitative comparison between an extensive accumulation of experimental data on the one hand, and the numerous theoretical models on the other. Instead, this chapter will attempt to glean a few qualitative conclusions from the existing experimental data. These results will then be compared with two general models which incorporate, in a qualitative manner, most of the proposed theories of the phonon-dislocation interaction. Until very recently, measurement of thermal conductivity was the only means available to probe the interaction between phonons and defects at phonon frequencies above the standard ultrasonic range of approx. = 10 9 Hz. The introductory paragraphs provide a brief review of the thermal-conductivity technique and the problems which are encountered in practice. There is also a brief presentation of the theoretical models and the complications that may occur in more realistic situations

  19. Possible displacement of mercury's dipole

    International Nuclear Information System (INIS)

    Ng, K.H.; Beard, D.B.

    1979-01-01

    Earlier attempts to model the Hermean magnetospheric field based on a planet-centered magnetic multipole field have required the addition of a quadrupole moment to obtain a good fit to space vehicle observations. In this work we obtain an equally satisfactory fit by assuming a null quadrupole moment and least squares fitting of the displacement of the planetary dipole from the center of the planet. We find a best fit for a dipole displacement from the planet center of 0.033 R/sub m/ away from the solar direction, 0.025 R/sub m/ toward dawn in the magnetic equatorial plane, and 0.189 R/sub m/ northward along the magnetic dipole axis, where R/sub m/ is the planet radius. Therefore the presence of a magnetic quadrupole moment is not ruled out. The compressed dipole field more completely represents the field in the present work than in previous work where the intrinsic quadrupole field was not included in the magnetopause surface and field calculations. Moreover, we have corrected a programing error in previous work in the computation of dipole tilt lambda away from the sun. We find a slight increase for the planet dipole moment of 190γR/sub m/ 3 and a dipole tilt angle lambda away from the sun. We find a slight increase for the planet moment of 190γR/sub m/ 3 and a dipole tilt angle lambda of only 1.2 0 away from the sun. All other parameters are essentially unchanged

  20. Dipole Bands in 196Hg

    International Nuclear Information System (INIS)

    Lawrie, J. J.; Lawrie, E. A.; Newman, R. T.; Sharpey-Schafer, J. F.; Smit, F. D.; Msezane, B.; Benatar, M.; Mabala, G. K.; Mutshena, K. P.; Federke, M.; Mullins, S. M.; Ncapayi, N. J.; Vymers, P.

    2011-01-01

    High spin states in 196 Hg have been populated in the 198 Pt(α,6n) reaction at 65 MeV and the level scheme has been extended. A new dipole band has been observed and a previously observed dipole has been confirmed. Excitation energies, spins and parities of these bands were determined from DCO ratio and linear polarization measurements. Possible quasiparticle excitations responsible for these structures are discussed.

  1. Medial subtalar dislocation: Case report

    Directory of Open Access Journals (Sweden)

    Manojlović Radovan

    2010-01-01

    Full Text Available Introduction. Subtalar dislocation (SI is a term that refers to an injury in which there is dislocation of the talonavicular and talocalcanear joint, although the tibiotalar joint is intact. Case Outline. A case of medial subtalar dislocation as a result of basketball injury, so-called 'basketball foot', is presented. Closed reposition in i.v. anaesthesia was performed with the patient in supine position and a knee flexed at 90 degrees. Longitudinal manual traction in line of deformity was carried out in plantar flexion. The reposition continued with abduction and eversion simultaneously increasing dorsiflexion. It was made in the first attempt and completed instantly. Rehabilitation was initiated after 5 weeks of immobilization. One year after the injury, the functional outcome was excellent with full range of motion and the patient was symptom-free. For better interpretation of roentgenogram, bone model of subtalar dislocation was made using the cadaver bone. Conclusion. Although the treatment of such injury is usually successful, diagnosis can be difficult because it is a rare injury, and moreover, X-ray of the injury can be confusing due to superposition of bones. Radiograms revealed superposition of the calcaneus, tarsal and metatarsal bones which was radiographically visualized in the anterior-posterior projection as one osseous block inward from the talus, and on the lateral view as in an osteal block below the tibial bone. Prompt recognition of these injuries followed by proper, delicately closed reduction under anaesthesia is crucial for achieving a good functional result in case of medial subtalar dislocation.

  2. Theoretical Expectations for the Muon's Electric Dipole Moment

    CERN Document Server

    Feng, J L; Shadmi, Y; Feng, Jonathan L; Matchev, Konstantin T.; Shadmi, Yael

    2001-01-01

    We examine the muon's electric dipole moment $\\dmu$ from a variety of theoretical perspectives. We point out that the reported deviation in the muon's g-2 can be due partially or even entirely to a new physics contribution to the muon's {\\em electric} dipole moment. In fact, the recent g-2 measurement provides the most stringent bound on $\\dmu$ to date. This ambiguity could be definitively resolved by the dedicated search for $\\dmu$ recently proposed. We then consider both model-independent and supersymmetric frameworks. Under the assumptions of scalar degeneracy, proportionality, and flavor conservation, the theoretical expectations for $\\dmu$ in supersymmetry fall just below the proposed sensitivity. However, non-degeneracy can give an order of magnitude enhancement, and lepton flavor violation can lead to $\\dmu$ of order $10^{-22}$ e cm, two orders of magnitude above the sensitivity of the $\\dmu$ experiment. We present compact expressions for leptonic dipole moments and lepton flavor violating amplitudes. ...

  3. A Note on the Dipole Coordinates

    OpenAIRE

    Kageyama, Akira; Sugiyama, Tooru; Watanabe, Kunihiko; Sato, Tetsuya

    2004-01-01

    A couple of orthogonal coordinates for dipole geometry are proposed for numerical simulations of plasma geophysics in the Earth's dipole magnetic field. These coordinates have proper metric profiles along field lines in contrast to the standard dipole coordinate system that is commonly used in analytical studies for dipole geometry.

  4. Medial peritalar fracture dislocation of the talar body

    Directory of Open Access Journals (Sweden)

    Jacob B. Stirton

    2015-04-01

    Full Text Available Peritalar fracture dislocations typically involve the talar neck and are classified according to Hawkins. To our knowledge, peritalar fracture dislocation involving the talar body has not been formally reported. In this article, we describe a case of peritalar fracture dislocation of the talar body. Keywords: Peritalar dislocation, Talus fracture, Talar body fracture dislocation, Medial subtalar dislocation

  5. An experimental study of dislocation loop nucleation

    International Nuclear Information System (INIS)

    Bounaud, J.Y.; Leteurtre, J.

    1975-01-01

    The nucleation of dislocation loops is experimentally studied by observing the demixion of the Burgers vectors of dislocation loops nucleated in copper whiskers irradiated in flexion by fission fragments at room temperature. The demixion of Burgers vectors is observed by the dimensional effects of dislocation loops: after irradiation, the applied stress is removed; the whisker shows a residual strain that is due to loops because, after an annealing treatment to evaporate dislocation loops, each whisker recovers its initial straight shape. Everywhere along the whisker, the radius of curvature is measured and plotted vs the max. applied stress. Estimations of the interstitial and vacancy dislocation loop nuclei are derived [fr

  6. Dislocation motion in tungsten: Atomistic input to discrete dislocation simulations

    Czech Academy of Sciences Publication Activity Database

    Srivastava, K.; Gröger, Roman; Weygand, D.; Gumbsch, P.

    2013-01-01

    Roč. 47, AUG (2013), s. 126-142 ISSN 0749-6419 R&D Projects: GA ČR GAP204/10/0255; GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : body -centered cubic * non-Schmid effects * anomalous slip * discrete dislocation dynamics Subject RIV: BM - Solid Matter Physics ; Magnetism; BM - Solid Matter Physics ; Magnetism (UFM-A) Impact factor: 5.971, year: 2013

  7. Energetics of dislocation nucleation under a nanoindenter

    International Nuclear Information System (INIS)

    Zhang Chuanli; Xu Guanshui

    2005-01-01

    We present an analysis of dislocation nucleation under an idealized nanoindenter based on the variational boundary integral formulation of the Peierls-Nabarro dislocation model. By solving the embryonic dislocation profiles, corresponding to the relative displacements between the two adjacent atomic layers along the slip plane, we have determined the critical conditions for athermal dislocation nucleation as well as the activation energies required to thermally activate embryonic dislocations from their stable to unstable saddle point configurations. The effect of the size of the indenter on the energetics of dislocation nucleation is quantitatively characterized. The result is compared with a simplified analysis based on the application of the Rice model for dislocation nucleation at a crack tip

  8. Theory of interacting dislocations on cylinders.

    Science.gov (United States)

    Amir, Ariel; Paulose, Jayson; Nelson, David R

    2013-04-01

    We study the mechanics and statistical physics of dislocations interacting on cylinders, motivated by the elongation of rod-shaped bacterial cell walls and cylindrical assemblies of colloidal particles subject to external stresses. The interaction energy and forces between dislocations are solved analytically, and analyzed asymptotically. The results of continuum elastic theory agree well with numerical simulations on finite lattices even for relatively small systems. Isolated dislocations on a cylinder act like grain boundaries. With colloidal crystals in mind, we show that saddle points are created by a Peach-Koehler force on the dislocations in the circumferential direction, causing dislocation pairs to unbind. The thermal nucleation rate of dislocation unbinding is calculated, for an arbitrary mobility tensor and external stress, including the case of a twist-induced Peach-Koehler force along the cylinder axis. Surprisingly rich phenomena arise for dislocations on cylinders, despite their vanishing Gaussian curvature.

  9. Energetics of dislocation nucleation under a nanoindenter

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Chuanli [College of Mechanical Engineering, Yangtze University, Jingzhou, Hubei 434023 (China); Department of Mechanical Engineering, University of California, Riverside, CA 92521 (United States); Xu Guanshui [Department of Mechanical Engineering, University of California, Riverside, CA 92521 (United States)]. E-mail: guanshui.xu@ucr.edu

    2005-07-25

    We present an analysis of dislocation nucleation under an idealized nanoindenter based on the variational boundary integral formulation of the Peierls-Nabarro dislocation model. By solving the embryonic dislocation profiles, corresponding to the relative displacements between the two adjacent atomic layers along the slip plane, we have determined the critical conditions for athermal dislocation nucleation as well as the activation energies required to thermally activate embryonic dislocations from their stable to unstable saddle point configurations. The effect of the size of the indenter on the energetics of dislocation nucleation is quantitatively characterized. The result is compared with a simplified analysis based on the application of the Rice model for dislocation nucleation at a crack tip.

  10. Arthroscopic treatment of acromioclavicular dislocation

    Directory of Open Access Journals (Sweden)

    Mihai T. Gavrilă

    2017-11-01

    Full Text Available A thorough understanding of biomechanical function of both acromioclavicular (AC and coracoclavicular (CC ligaments, stimulated surgeons to repair high-grade AC dislocation using arthroscopic technique. This technique necessitates a clear understanding of shoulder anatomy, especially of the structures in proximity to the clavicle and coracoid process and experiences in arthroscopic surgery. The follow case describes an arthroscopic technique used to treat AC dislocation in young man 30 years old, who suffered an injury at right shoulder. Results were similar to those obtained using open surgery and this encouraged us to continue utilization of this method. As a conclusion, arthroscopic treatment of AC separation is one of the best options as surgical treatment. Early results suggested that immediate anatomic reduction of an acute AC separation usually provides satisfactory clinical results at intermediate-term follow-up.

  11. Dislocation arrangement in the plastic zone for propagating cracks in nickel

    International Nuclear Information System (INIS)

    Kobayashi, S.; Ohr, S.M.

    1985-01-01

    Since nickel is a metal of high stacking fault energy, it is of interest to study the arrangement of dislocations in the plastic zone for propagating cracks and to compare the results with those found in metals of low stacking fault energy. It has been found that two distinct distributions of dislocations in the plastic zone are associated with cracks in nickel. In one of these, the plastic zone appeared as a thin ribbon and consisted of a number of partial dislocations with stacking fault fringes. From contrast analysis and stereoscopic observations, the crack was found to be approximately mode III type, and the plane of the plastic zone was identified as (111). The crack geometry was very similar to that observed in metals of low stacking fault energy, namely, stainless steel and copper. The second type of plastic zone observed was not in the form of a thin ribbon; that is, the dislocations in the plastic zone were not split into partial dislocations. Since the dislocations were not split, they cross-slipped readily from the original slip plane and formed a broad plastic zone

  12. Dislocation structures of Σ3 {112} twin boundaries in face centered cubic metals

    Science.gov (United States)

    Wang, J.; Anderoglu, O.; Hirth, J. P.; Misra, A.; Zhang, X.

    2009-07-01

    High resolution transmission electron microscopy of nanotwinned Cu films revealed Σ3 {112} incoherent twin boundaries (ITBs), with a repeatable pattern involving units of three {111} atomic planes. Topological analysis shows that Σ3 {112} ITBs adopt two types of atomic structure with differing arrangements of Shockley partial dislocations. Atomistic simulations were performed for Cu and Al. These studies revealed the structure of the two types of ITBs, the formation mechanism and stability of the associated 9R phase, and the influence of stacking fault energies on them. The results suggest that Σ3 {112} ITBs may migrate through the collective glide of partial dislocations.

  13. The relative stability of dislocations embedded in the β phase matrix and in martensite phases in copper based alloys

    International Nuclear Information System (INIS)

    Lovey, Francisco; Hazarabedian, Alfredo; Garces, Jorge

    1988-01-01

    Dislocations are formed during martensitic transformations in shape memory alloys. The number of dislocations (with Burgers vector →b β = a o and line direction in the β phase) increases when the material is subjected to thermoelastic or pseudoelastic cycles. The dislocations are accumulated in the sample and are incorporated in the corresponding growing phase. The relative energy of the dislocations when embedded in the parent phase (with respect to b) one or another variant of martensite is evaluated in this work. The crystallographic changes of the dislocations provide a primary selection rule for those martensite variants in which the dislocations have the lowest energy. In order to proceed more quantitatively a full calculation of the dislocation energies has to be performed using the anisotropic theory. In this work these calculations have been made on the basis of measured elastic constants of the β and 2H phases of a Cu-Al-Ni alloy. It is concluded that those martensite variants are favored energetically whose basal plane contains the Burgers vector and line direction of the dislocations (Splitting into Shockley partials is suggested to occur). The importance of this result for the two-way shape memory (TWSM) effect is discussed and a mechanism is proposed which can account for the multiplication of dislocations during the transformation. (Author)

  14. Empirical potential and elasticity theory modelling of interstitial dislocation loops in UO2 for cluster dynamics application

    International Nuclear Information System (INIS)

    Le-Prioux, Arno

    2017-01-01

    During irradiation in reactor, the microstructure of UO 2 changes and deteriorates, causing modifications of its physical and mechanical properties. The kinetic models used to describe these changes such as cluster dynamics (CRESCENDO calculation code) consider the main microstructural elements that are cavities and interstitial dislocation loops, and provide a rather rough description of the loop thermodynamics. In order to tackle this issue, this work has led to the development of a thermodynamic model of interstitial dislocation loops based on empirical potential calculations. The model considers two types of interstitial dislocation loops on two different size domains: Type 1: Dislocation loops similar to Frank partials in F.C.C. materials which are stable in the smaller size domain. Type 2: Perfect dislocation loops of Burgers vector (a/2)(110) stable in the larger size domain. The analytical formula used to compute the interstitial dislocation loop formation energies is the one for circular loops which has been modified in order to take into account the effects of the dislocation core, which are significant at smaller sizes. The parameters have been determined by empirical potential calculations of the formation energies of prismatic pure edge dislocation loops. The effect of the habit plane reorientation on the formation energies of perfect dislocation loops has been taken into account by a simple interpolation method. All the different types of loops seen during TEM observations are thus accounted for by the model. (author) [fr

  15. Possible origin of the discrepancy in Peierls stresses of fcc metals: First-principles simulations of dislocation mobility in aluminum

    Science.gov (United States)

    Shin, Ilgyou; Carter, Emily A.

    2013-08-01

    Dislocation motion governs the strength and ductility of metals, and the Peierls stress (σp) quantifies dislocation mobility. σp measurements carry substantial uncertainty in face-centered cubic (fcc) metals, and σp values can differ by up to two orders of magnitude. We perform first-principles simulations based on orbital-free density functional theory (OFDFT) to calculate the most accurate currently possible σp for the motion of (1)/(2)111 dislocations in fcc Al. We predict the σps of screw and edge dislocations (dissociated in their equilibrium state) to be 1.9×10-4G and 4.9×10-5G, respectively (G is the shear modulus). These values fall within the range of measurements from mechanical deformation tests (10-4-10-5G). OFDFT also finds a new metastable structure for a screw dislocation not seen in earlier simulations, in which a dislocation core on the glide plane does not dissociate into partials. The corresponding σp for this undissociated dislocation is predicted to be 1.1×10-2G, which agrees with typical Bordoni peak measurements (10-2-10-3G). The calculated σps for dissociated and undissociated screw dislocations differ by two orders of magnitude. The presence of undissociated, as well as dissociated, screw dislocations may resolve the decades-long mystery in fcc metals regarding the two orders of magnitude discrepancy in σp measurements.

  16. Beam Manipulation with an RF Dipole

    International Nuclear Information System (INIS)

    Bai, M.

    1999-01-01

    Coherent betatron motion adiabatically excited by an RF dipole has been successfully employed to overcome strong intrinsic spin depolarization resonances in the AGS, while a solenoid partial snake has been used to correct imperfection spin resonances. The experimental results showed that a full spin flip was obtained in passing through an intrinsic spin resonance when all the beam particles were forced to oscillate coherently at a large amplitude without diluting the beam emittance. With this method, they have successfully accelerated polarized beam up to 23.5 GeV/c. A new type of second order spin resonances was also discovered. As a non-destructive manipulation, this method can also be used for nonlinear beam dynamics studies and beam diagnosis such as measuring phase advance and betatron amplitude function

  17. In situ TEM observations of reverse dislocation motion upon unloading in tensile-deformed UFG aluminium

    International Nuclear Information System (INIS)

    Mompiou, Frédéric; Caillard, Daniel; Legros, Marc; Mughrabi, Haël

    2012-01-01

    Loading–unloading cycles have been performed on ultrafine-grained (UFG) aluminium inside a transmission electron microscope (TEM). The interaction of dislocations with grain boundaries, which is supposed to be at the origin of the inelastic behaviour of this class of materials, differs according to the main character of the dislocation segments involved in pile-ups. Pile-ups are formed by spiral sources and lead to the incorporation of dislocations into grain boundaries (GBs) during loading. Upon unloading, partial re-emission of dislocations from GBs can be observed. Stress and strain measurements performed during these in situ TEM loading–unloading experiments are in agreement with the rather large inelastic reverse strains observed during unloading in loading–unloading tests on bulk macroscopic UFG aluminium specimens.

  18. Dipole Resonances of 76Ge

    Science.gov (United States)

    Ilieva, R. S.; Cooper, N.; Werner, V.; Rusev, G.; Pietralla, N.; Kelly, J. H.; Tornow, W.; Yates, S. W.; Crider, B. P.; Peters, E.

    2013-10-01

    Dipole resonances in 76Ge have been studied using the method of Nuclear Resonance Fluorescence (NRF). The experiment was performed using the Free Electron Laser facility at HI γS/TUNL, which produced linearly polarised quasi-monoenergetic photons in the 4-9 MeV energy range. Photon strength, in particular dipole strength, is an important ingredient in nuclear reaction calculations, and recent interest in its study has been stimulated by observations of a pygmy dipole resonance near the neutron separation energy Sn of certain nuclei. Furthermore, 76Ge is a candidate for 0 ν 2 β -decay. The results are complimentary to a relevant experiment done at TU Darmstadt using Bremsstrahlung beams. Single-resonance parities and a preliminary estimate of the total photo-excitation cross section will be presented. This work was supported by the U.S. DOE under grant no. DE-FG02-91ER40609.

  19. Stacks of SPS Dipole Magnets

    CERN Multimedia

    1974-01-01

    Stacks of SPS Dipole Magnets ready for installation in the tunnel. The SPS uses a separated function lattice with dipoles for bending and quadrupoles for focusing. The 6.2 m long normal conducting dipoles are of H-type with coils that are bent-up at the ends. There are two types, B1 (total of 360) and B2 (384). Both are for a maximum field of 1.8 Tesla and have the same outer dimensions (450x800 mm2 vxh) but with different gaps (B1: 39x129 mm2, B2: 52x92 mm2) tailored to the beam size. The yoke, made of 1.5 mm thick laminations, consists of an upper and a lower half joined together in the median plane once the coils have been inserted.

  20. Cryogenics in CEBAF HMS dipole

    International Nuclear Information System (INIS)

    Bogensberger, P.; Ramsauer, F.; Brindza, P.; Wines, R.; Koefler, H.

    1994-01-01

    The paper will report upon the final design, manufacturing and tests of CEBAF's HMS Dipole cryogenic equipment. The liquid nitrogen circuits, the helium circuits and thermal insulation of the magnet will be addressed. The cryogenic reservoir and control module as an integral part of the HMS Dipole magnet will be presented. The construction, manufacturing, tests and final performance of the HMS Dipole cryogenic system will be reported. The LN 2 circuit and the He circuit are tied together by the control system for cool down, normal operation and standby. This system monitors proper temperature differences between both circuits and controls the cryogenic supply to meet the constraints. Implementation of the control features for the cryogenic system into the control system will be reported

  1. Derivation of the dipole map

    International Nuclear Information System (INIS)

    Ali, Halima; Punjabi, Alkesh; Boozer, Allen

    2004-01-01

    In our method of maps [Punjabi et al., Phy. Rev. Lett. 69, 3322 (1992), and Punjabi et al., J. Plasma Phys. 52, 91 (1994)], symplectic maps are used to calculate the trajectories of magnetic field lines in divertor tokamaks. Effects of the magnetic perturbations are calculated using the low MN map [Ali et al., Phys. Plasmas 11, 1908 (2004)] and the dipole map [Punjabi et al., Phys. Plasmas 10, 3992 (2003)]. The dipole map is used to calculate the effects of externally located current carrying coils on the trajectories of the field lines, the stochastic layer, the magnetic footprint, and the heat load distribution on the collector plates in divertor tokamaks [Punjabi et al., Phys. Plasmas 10, 3992 (2003)]. Symplectic maps are general, efficient, and preserve and respect the Hamiltonian nature of the dynamics. In this brief communication, a rigorous mathematical derivation of the dipole map is given

  2. Formation of stacking faults and the screw dislocation-driven growth: a case study of aluminum nitride nanowires.

    Science.gov (United States)

    Meng, Fei; Estruga, Marc; Forticaux, Audrey; Morin, Stephen A; Wu, Qiang; Hu, Zheng; Jin, Song

    2013-12-23

    Stacking faults are an important class of crystal defects commonly observed in nanostructures of close packed crystal structures. They can bridge the transition between hexagonal wurtzite (WZ) and cubic zinc blende (ZB) phases, with the most known example represented by the "nanowire (NW) twinning superlattice". Understanding the formation mechanisms of stacking faults is crucial to better control them and thus enhance the capability of tailoring physical properties of nanomaterials through defect engineering. Here we provide a different perspective to the formation of stacking faults associated with the screw dislocation-driven growth mechanism of nanomaterials. With the use of NWs of WZ aluminum nitride (AlN) grown by a high-temperature nitridation method as the model system, dislocation-driven growth was first confirmed by transmission electron microscopy (TEM). Meanwhile numerous stacking faults and associated partial dislocations were also observed and identified to be the Type I stacking faults and the Frank partial dislocations, respectively, using high-resolution TEM. In contrast, AlN NWs obtained by rapid quenching after growth displayed no stacking faults or partial dislocations; instead many of them had voids that were associated with the dislocation-driven growth. On the basis of these observations, we suggest a formation mechanism of stacking faults that originate from dislocation voids during the cooling process in the syntheses. Similar stacking fault features were also observed in other NWs with WZ structure, such as cadmium sulfide (CdS) and zinc oxide (ZnO).

  3. Coupled-resonator waveguide perfect transport single-photon by interatomic dipole-dipole interaction

    Science.gov (United States)

    Yan, Guo-an; Lu, Hua; Qiao, Hao-xue; Chen, Ai-xi; Wu, Wan-qing

    2018-06-01

    We theoretically investigate single-photon coherent transport in a one-dimensional coupled-resonator waveguide coupled to two quantum emitters with dipole-dipole interactions. The numerical simulations demonstrate that the transmission spectrum of the photon depends on the two atoms dipole-dipole interactions and the photon-atom couplings. The dipole-dipole interactions may change the dip positions in the spectra and the coupling strength may broaden the frequency band width in the transmission spectrum. We further demonstrate that the typical transmission spectra split into two dips due to the dipole-dipole interactions. This phenomenon may be used to manufacture new quantum waveguide devices.

  4. Traumatic hip dislocation: early MRI findings

    International Nuclear Information System (INIS)

    Laorr, A.; Greenspan, A.; Anderson, M.W.; Moehring, H.D.; McKinley, T.

    1995-01-01

    Objective of this study was to present the spectrum of early magnetic resonance imaging (MRI) findings following traumatic dislocation of the femoral head, and to identify any associated injuries. Prospective MRI of both hips was performed on 18 patients within 5 weeks of a traumatic femoral head dislocation. The interval between the time of injury and the imaging studies ranged from 2 to 35 days. Posterior dislocation was present in 14 patients and anterior dislocation in 4 patients. In the majority of cases, we performed axial T1, coronal T1, and coronal T2 * (MPGR) sequences. MRI can effectively identify and quantify the muscle injury and joint effusion that invariably accompany traumatic hip dislocations. It is also useful for demonstrating trabecular bone contusion (trabecular injury) and iliofemoral ligament injury, which occur commonly with acute hip dislocation. (orig./VHE)

  5. Atraumatic Anterior Dislocation of the Hip Joint

    Directory of Open Access Journals (Sweden)

    Tadahiko Ohtsuru

    2015-01-01

    Full Text Available Dislocation of the hip joint in adults is usually caused by high-energy trauma such as road traffic accidents or falls from heights. Posterior dislocation is observed in most cases. However, atraumatic anterior dislocation of the hip joint is extremely rare. We present a case of atraumatic anterior dislocation of the hip joint that was induced by an activity of daily living. The possible causes of this dislocation were anterior capsule insufficiency due to developmental dysplasia of the hip, posterior pelvic tilt following thoracolumbar kyphosis due to vertebral fracture, and acetabular anterior coverage changes by postural factor. Acetabular anterior coverage changes in the sagittal plane were measured using a tomosynthesis imaging system. This system was useful for elucidation of the dislocation mechanism in the present case.

  6. Effects of dislocations on electron channeling

    International Nuclear Information System (INIS)

    George, Juby; Pathak, A P

    2009-01-01

    The phenomenon of electron channeling in a crystal affected by dislocations is considered. Earlier we had considered the quantum aspects of the positron channeling in a crystal bent by dislocations where the effects of longitudinal motion of the particle were also considered along with the transverse motion. In this paper, the effective potential for the electron case is found for the two regions of dislocation-affected channel. There is considerable shift in the potential minima due to dislocations. The frequency and the corresponding spectrum of the channeling radiation due to electrons channeling through the perfect channel and the two regions of dislocation-affected channels are calculated. The spectral distribution of radiation intensity changes with the parameters of dislocation. The continuity of wavefunctions and their derivatives is used at the three boundaries and the reflection and transmission coefficients are found using these boundary conditions in the same way as in the positron case.

  7. Rare Inferior Shoulder Dislocation (Luxatio Erecta)

    OpenAIRE

    Cift, Hakan; Soylemez, Salih; Demiroglu, Murat; Ozkan, Korhan; Ozden, Vahit Emre; Ozkut, Afsar T.

    2015-01-01

    Although shoulder dislocations have been seen very frequently, inferior dislocation of shoulder constitutes only 0.5% of all shoulder dislocations. We share our 4 patients with luxatio erecta and present their last clinical control. 2 male and 2 female Caucasian patients were diagnosed as luxatio erecta. Patients’ ages were 78, 62, 65, and 76. All patients’ reduction was done by traction-abduction and contour traction maneuver in the operating room. The patients had no symptoms and no limitat...

  8. Dislocation density changes in nickel under creep

    International Nuclear Information System (INIS)

    Moiseeva, I.V.; Okrainets, P.N.; Pishchak, V.K.

    1984-01-01

    Variation in dislocation density was studied in the process of nickel creep p at t=900 deg c and σ=2 kgf/mm 2 . The dislocation structure was studied independently by the X-ray technique and transmission electron-microscopy. The e two methods show good conformity of results by comparison. It is concluded that independent determination of dislocation density under creep is possible us sing the X-ray technique

  9. Piles of dislocation loops in real crystals

    International Nuclear Information System (INIS)

    Dubinko, V.I.; Turkin, A.A.; Yanovskij, V.V.

    1985-01-01

    Behaviour of piles of dislocation loops in crystals was studied in order to define metal swelling under irradiation. Energy of pile interaction with point defects and intrinsic pile energy are studied in the framework of the linear elasticity theory. Preference of dislocation pile calculated in the paper decreases with radiation dose hence, material swelling rate also decreases. Creation of conditions, which assume an existence of piles of dislocation loops being stable under irradiation, is of particular interest

  10. Imaging findings of anterior hip dislocations

    Energy Technology Data Exchange (ETDEWEB)

    Pfeifer, Kyle [Mallinckrodt Institute of Radiology, Department of Radiology, St. Louis, MO (United States); Leslie, Michael [Yale School of Medicine, Department of Orthopedics and Rehabilitation, New Haven, CT (United States); Menn, Kirsten; Haims, Andrew [Yale University School of Medicine, Department of Radiology and Biomedical Imaging, New Haven, CT (United States)

    2017-06-15

    Anterior hip dislocations are rare orthopedic emergencies resulting from high-energy trauma and have unique imaging characteristics on radiography, computed tomography (CT), and magnetic resonance imaging (MRI). Imaging findings on CT and MRI allow for the prompt recognition and classification of anterior hip dislocations, which guides patient management and reduces complications. The purpose of this article is to review imaging findings of anterior hip dislocations, specifically focusing on CT and MRI. (orig.)

  11. Raising the last LEP dipole

    CERN Multimedia

    Maximilien Brice

    2002-01-01

    The last of the 3280 dipole magnets from the Large Electron-Positron (LEP) collider is seen on its journey to the surface on 12 February 2002. The LEP era, which began at CERN in 1989 and ended 2000, comes to an end.

  12. Locating a buried magnetic dipole

    Energy Technology Data Exchange (ETDEWEB)

    Caffey, T.W.H.

    1977-01-01

    The theoretical basis and required computations for locating a buried magnetic dipole are outlined. The results are compared with measurements made with a tiltable coil lowered to a depth of 20 m in a vertical borehole within a three-layered earth. this work has application to the rescue of trapped miners. 3 figures, 1 table. (RWR)

  13. Particle electric dipole-moments

    Energy Technology Data Exchange (ETDEWEB)

    Pendlebury, J M [Sussex Univ., Brighton (United Kingdom)

    1997-04-01

    The incentive to detect particle electric dipole-moments, as a window on time-reversal violation, remains undiminished. Efforts to improve the measurements for the neutron, the electron and some nuclei are still making rapid progress as more powerful experimental methods are brought to bear. A new measurement for the neutron at ILL is presented. (author). 7 refs.

  14. 5cm aperture dipole studies

    International Nuclear Information System (INIS)

    McInturff, A.D.; Bossert, R.; Carson, J.; Fisk, H.E.; Hanft, R.; Kuchnir, M.; Lundy, R.; Mantech, P.; Strait, J.

    1986-01-01

    The results obtained during the evolution of the design, construction, and testing program of the design ''B'' dipole are presented here. Design ''B'' is one of the original three competing designs for the Superconducting Super Collider ''SSC'' arc dipoles. The final design parameters were as follows: air cored (less than a few percent of the magnetic field derived from any iron present), aluminum collared, two layered winding, 5.5T maximum operating field, and a 5 cm cold aperture. There have been fourteen 64 cm long 5 cm aperture model dipoles cold tested (at 4.3K and less) in this program so far. There was a half length full size (6m) mechanical analog (M-10) built and tested to check the cryostat's mechanical design under ramping and quench conditions. Several deviations from the ''Tevatron'' dipole fabrication technique were incorporated, for example the use of aluminum collars instead of stainless steel. The winding technique variations explored were ''dry welding,'' a technique with the cable covered with Kapton insulation only and ''wet winding'' where the Kapton was covered with a light coat of ''B'' stage epoxy. Test data include quench currents, field quality (Fourier multipole co-efficients), coil magnetization, conductor current performance, and coil loading. Quench current, loss per cycle, and harmonics were measured as a function of the magnitude and rate of change of the magnetic field, and helium bath temperature

  15. The Collider dipole magnet program

    International Nuclear Information System (INIS)

    Baldi, R.W.; Bailey, R.; Bever, D.; Bogart, L.; Gigg, G.; Packer, M.; Page, L.; Stranberg, N.

    1991-01-01

    The Superconducting Super Collider will consist of more large superconducting magnets than have been built to date. Over 12,000 superconducting magnets are required and more than 8,000 will be Collider dipoles. The dipole magnet program is on the critical path of the project and requires the optimized utilization of the Nation's resources - National Laboratories, Universities and Industry. General Dynamics and Westinghouse Electric Corporation have been chosen as the Leader and Follower companies for the design of producible magnets and the manufacturing of the SSC dipoles. Industry has the necessary experience, skills and facilities required to produce reliable and cost effective dipole magnets. At peak production, 10 CDMs per day, very large quantities (nearly 130 metric tonnes/day) of materials will have to be procured from companies nationwide and fabricated into defect-free magnets. A key element of the SSCL's strategy to produce the most efficient CDM program is to employ the Leader-Follower approach, with the Leader transferring technology from the laboratories to the Leader's facility, fully integrating the Follower in the producibility and tooling/factory design efforts, and assisting the Follower in magnet qualification tests. General Dynamics is ready to help build America's most powerful research tool. Management is in place, the facilities are ready for activation and resources are available for immediate assignment

  16. A Tale of Two Dipoles

    DEFF Research Database (Denmark)

    Andersen, Jørgen Bach

    2006-01-01

    A number of antenna topics may be treated by studying just two parallel, closely spaced electrical dipoles. They form an array and they may be coupled to form a single antenna with one port, or coupled through a coupling network to form a multiport antenna. The situations discussed are the creation...

  17. Energy flow around a moving dislocation

    International Nuclear Information System (INIS)

    Koizumi, H; Kirchner, H O K

    2009-01-01

    A dislocation moving in a lattice emits lattice waves. We study the energy flow accompanying the lattice wave emission in a molecular dynamics situation. About two thirds of the static free energy are emitted as lattice waves from the moving dislocation. Work done by the region around the dislocation helps to initiate the motion from the unstable equilibrium state under a small applied stress, or to compensate the energy emitted as lattice waves when the dislocation makes a long distance motion under a larger stress.

  18. Epidemiology of Isolated Acromioclavicular Joint Dislocation

    Directory of Open Access Journals (Sweden)

    Claudio Chillemi

    2013-01-01

    Full Text Available Background. Acromioclavicular (AC joint dislocation is a common shoulder problem. However, information about the basic epidemiological features of this condition is scarce. The aim of this study is to analyze the epidemiology of isolated AC dislocation in an urban population. Materials and Methods. A retrospective database search was performed to identify all patients with an AC dislocation over a 5-year period. Gender, age, affected side and traumatic mechanism were taken into account. X-rays were reviewed by two of the authors and dislocations were classified according to the Rockwood’s criteria. Results. A total of 108 patients, with a mean age of 37.5 years were diagnosed with AC dislocation. 105 (97.2% had an isolated AC dislocation, and 3 (2.8% were associated with a clavicle fracture. The estimated incidence was 1.8 per 10000 inhabitants per year and the male-female ratio was 8.5 : 1. 50.5% of all dislocations occurred in individuals between the ages of 20 and 39 years. The most common traumatic mechanism was sport injury and the most common type of dislocation was Rockwood type III. Conclusions. Age between 20 and 39 years and male sex represent significant demographic risk factors for AC dislocation.

  19. Multiscale dipole relaxation in dielectric materials

    DEFF Research Database (Denmark)

    Hansen, Jesper Schmidt

    2016-01-01

    Dipole relaxation from thermally induced perturbations is investigated on different length scales for dielectric materials. From the continuum dynamical equations for the polarisation, expressions for the transverse and longitudinal dipole autocorrelation functions are derived in the limit where ...

  20. Dipole rescattering and the nuclear structure function

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, F. [Depto de Ciencias Exatas e da Terra, Universidade Federal de Sao Paulo, SP (Brazil); Goncalves, V. P. [Instituto de Fisica e Matematica, Universidade Federal de Pelotas, Caixa Postal 354, CEP 96010-900, Pelotas, RS (Brazil); Navarra, F. S.; Oliveira, E. G. [Instituto de Fisica, Universidade de Sao Paulo Rua do Matao, Travessa R, 187, 05508-090 Sao Paulo, SP (Brazil)

    2013-03-25

    In the framework of the dipole model, we study the effects of the dipole multiple scatterings in a nuclear target and compute the nuclear structure function. We compare different unitarization schemes and confront our results with the E665 data.

  1. Metal working and dislocation structures

    DEFF Research Database (Denmark)

    Hansen, Niels

    2007-01-01

    Microstructural observations are presented for different metals deformed from low to high strain by both traditional and new metal working processes. It is shown that deformation induced dislocation structures can be interpreted and analyzed within a common framework of grain subdivision on a finer...... and finer scale down to the nanometer dimension, which can be reached at ultrahigh strains. It is demonstrated that classical materials science and engineering principles apply from the largest to the smallest structural scale but also that new and unexpected structures and properties characterize metals...

  2. Dynamics of a nonlinear dipole vortex

    DEFF Research Database (Denmark)

    Hesthaven, J.S.; Lynov, Jens-Peter; Nielsen, A.H.

    1995-01-01

    A localized stationary dipole solution to the Euler equations with a relationship between the vorticity and streamfunction given as omega=-psi+psi(3) is presented. By numerical integration of the Euler equations this dipole is shown to be unstable. However, the initially unstable dipole reorganiz...

  3. Polarization electric dipole moment in nonaxial nuclei

    International Nuclear Information System (INIS)

    Denisov, V.Yu.; Davidovskaya, O.I.

    1996-01-01

    An expression for the macroscopic polarization electric dipole moment is obtained for nonaxial nuclei whose radii of the proton and neutron surfaces are related by a linear equation. Dipole transitions associated with the polarization electric dipole moment are analyzed for static and dynamical multipole deformations

  4. Dislocation/hydrogen interaction mechanisms in hydrided nanocrystalline palladium films

    International Nuclear Information System (INIS)

    Amin-Ahmadi, Behnam; Connétable, Damien; Fivel, Marc; Tanguy, Döme; Delmelle, Renaud; Turner, Stuart; Malet, Loic; Godet, Stephane; Pardoen, Thomas; Proost, Joris; Schryvers, Dominique

    2016-01-01

    The nanoscale plasticity mechanisms activated during hydriding cycles in sputtered nanocrystalline Pd films have been investigated ex-situ using advanced transmission electron microscopy techniques. The internal stress developing within the films during hydriding has been monitored in-situ. Results showed that in Pd films hydrided to β-phase, local plasticity was mainly controlled by dislocation activity in spite of the small grain size. Changes of the grain size distribution and the crystallographic texture have not been observed. In contrast, significant microstructural changes were not observed in Pd films hydrided to α-phase. Moreover, the effect of hydrogen loading on the nature and density of dislocations has been investigated using aberration-corrected TEM. Surprisingly, a high density of shear type stacking faults has been observed after dehydriding, indicating a significant effect of hydrogen on the nucleation energy barriers of Shockley partial dislocations. Ab-initio calculations of the effect of hydrogen on the intrinsic stable and unstable stacking fault energies of palladium confirm the experimental observations.

  5. Compound dorsal dislocation of lunate with trapezoid fracture

    Directory of Open Access Journals (Sweden)

    Bong-Sung Kim

    2016-12-01

    Full Text Available We report about a dorsal dislocation of the lunate accompanied by a trapezoid fracture in a 41-year old male patient after a motorcycle accident. The lunate dislocation with no dorsal or volar intercalated segment instability (DISI, VISI was diagnosed by x-ray whereas the trapezoid fracture was only diagnosable by computed tomography. A closed reduction and internal fixation of the lunate by two Kirschner wires was performed, the trapezoid fracture was conservatively treated. Surgery was followed by immobilization, intense physiotherapy and close follow-up. Even though complaints such as swelling and pain subsided during the course of rehabilitation, partial loss of strength and range of motion remained even after 16 months. In conclusion, a conservative treatment of trapezoid fractures seems to be sufficient in most cases. Closed reduction with Kwire fixation led to an overall satisfactory result in our case. For dorsal lunate dislocations in general, open reduction should be performed when close reduction is unsuccessful or DISI/VISI are observed in radiographs after attempted close reduction.

  6. A numerical spectral approach to solve the dislocation density transport equation

    International Nuclear Information System (INIS)

    Djaka, K S; Taupin, V; Berbenni, S; Fressengeas, C

    2015-01-01

    A numerical spectral approach is developed to solve in a fast, stable and accurate fashion, the quasi-linear hyperbolic transport equation governing the spatio-temporal evolution of the dislocation density tensor in the mechanics of dislocation fields. The approach relies on using the Fast Fourier Transform algorithm. Low-pass spectral filters are employed to control both the high frequency Gibbs oscillations inherent to the Fourier method and the fast-growing numerical instabilities resulting from the hyperbolic nature of the transport equation. The numerical scheme is validated by comparison with an exact solution in the 1D case corresponding to dislocation dipole annihilation. The expansion and annihilation of dislocation loops in 2D and 3D settings are also produced and compared with finite element approximations. The spectral solutions are shown to be stable, more accurate for low Courant numbers and much less computation time-consuming than the finite element technique based on an explicit Galerkin-least squares scheme. (paper)

  7. Strain Fields And Crystallographic Characteristics Of Interstitial Dislocation Loops of Various Geometry In BCC Iron

    International Nuclear Information System (INIS)

    Sivak, Alexander B.; Chernov, Viatcheslav M.; Romanov, Vladimir A.

    2008-01-01

    The formation energy, the relaxation volume, the dipole-force tensor, the self strain tensor and strain fields of interstitial dislocation loops in bcc iron (clusters of self interstitial atoms) have been calculated by molecular statics. Hexagonal and square dislocation loops of different types with different Burgers vectors, directions of dislocation segments and habit planes containing up to ∼2500 self-interstitials have been considered. Analytical expressions describing size dependence of the formation energy, the relaxation volume and the self strain tensor for the loops stated have been obtained. The most energetically favorable loops are hexagonal loops with Burgers vector a/2 and habit plane {11x}, where x takes values in the range from 0 to 1 depending on the loop size. The formation energy of a loops with and dislocation segments is ∼14% and 23% greater than that of hexagonal a/2 loops at N>500, respectively. The analysis of the formation energies of a/2 and a loops demonstrated that the nucleation of an a loop by joining of two a/2 loops is possible when the total number of constituent self-interstitials in these loops is larger than 13

  8. Formation of disorientations in dislocation structures during plastic deformation

    DEFF Research Database (Denmark)

    Pantleon, W.

    2002-01-01

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

  9. Hybrid dislocated control and general hybrid projective dislocated synchronization for the modified Lue chaotic system

    International Nuclear Information System (INIS)

    Xu Yuhua; Zhou Wuneng; Fang Jianan

    2009-01-01

    This paper introduces a modified Lue chaotic system, and some basic dynamical properties are studied. Based on these properties, we present hybrid dislocated control method for stabilizing chaos to unstable equilibrium and limit cycle. In addition, based on the Lyapunov stability theorem, general hybrid projective dislocated synchronization (GHPDS) is proposed, which includes complete dislocated synchronization, dislocated anti-synchronization and projective dislocated synchronization as its special item. The drive and response systems discussed in this paper can be strictly different dynamical systems (including different dimensional systems). As examples, the modified Lue chaotic system, Chen chaotic system and hyperchaotic Chen system are discussed. Numerical simulations are given to show the effectiveness of these methods.

  10. Hybrid dislocated control and general hybrid projective dislocated synchronization for the modified Lue chaotic system

    Energy Technology Data Exchange (ETDEWEB)

    Xu Yuhua [College of Information Science and Technology, Donghua University, Shanghai 201620 (China) and Department of Maths, Yunyang Teacher' s College, Hubei 442000 (China)], E-mail: yuhuaxu2004@163.com; Zhou Wuneng [College of Information Science and Technology, Donghua University, Shanghai 201620 (China)], E-mail: wnzhou@163.com; Fang Jianan [College of Information Science and Technology, Donghua University, Shanghai 201620 (China)

    2009-11-15

    This paper introduces a modified Lue chaotic system, and some basic dynamical properties are studied. Based on these properties, we present hybrid dislocated control method for stabilizing chaos to unstable equilibrium and limit cycle. In addition, based on the Lyapunov stability theorem, general hybrid projective dislocated synchronization (GHPDS) is proposed, which includes complete dislocated synchronization, dislocated anti-synchronization and projective dislocated synchronization as its special item. The drive and response systems discussed in this paper can be strictly different dynamical systems (including different dimensional systems). As examples, the modified Lue chaotic system, Chen chaotic system and hyperchaotic Chen system are discussed. Numerical simulations are given to show the effectiveness of these methods.

  11. Dislocation creation and void nucleation in FCC ductile metals under tensile loading: a general microscopic picture.

    Science.gov (United States)

    Pang, Wei-Wei; Zhang, Ping; Zhang, Guang-Cai; Xu, Ai-Guo; Zhao, Xian-Geng

    2014-11-10

    Numerous theoretical and experimental efforts have been paid to describe and understand the dislocation and void nucleation processes that are fundamental for dynamic fracture modeling of strained metals. To date an essential physical picture on the self-organized atomic collective motions during dislocation creation, as well as the essential mechanisms for the void nucleation obscured by the extreme diversity in structural configurations around the void nucleation core, is still severely lacking in literature. Here, we depict the origin of dislocation creation and void nucleation during uniaxial high strain rate tensile processes in face-centered-cubic (FCC) ductile metals. We find that the dislocations are created through three distinguished stages: (i) Flattened octahedral structures (FOSs) are randomly activated by thermal fluctuations; (ii) The double-layer defect clusters are formed by self-organized stacking of FOSs on the close-packed plane; (iii) The stacking faults are formed and the Shockley partial dislocations are created from the double-layer defect clusters. Whereas, the void nucleation is shown to follow a two-stage description. We demonstrate that our findings on the origin of dislocation creation and void nucleation are universal for a variety of FCC ductile metals with low stacking fault energies.

  12. Traumatic Posterior Atlantoaxial Dislocation Without Associated Fracture but With Neurological Deficit

    Science.gov (United States)

    Xu, Yong; Li, Feng; Guan, Hanfeng; Xiong, Wei

    2015-01-01

    Abstract Posterior atlantoaxial dislocation without odontoid fracture is extremely rare and often results in fatal spinal cord injury. According to the reported literature, all cases presented mild or no neurologic deficit, with no definite relation to upper spinal cord injury. Little is reported about traumatic posterior atlantoaxial dislocation, with incomplete quadriplegia associated with a spinal cord injury. We present a case of posterior atlantoaxial dislocation without associated fracture, but with quadriplegia, and accompanying epidural hematoma and subarachnoid hemorrhage. The patient underwent gentle traction in the neutral position until repeated cranial computed tomography revealed no progression of the epidural hematoma. Thereafter, the atlantoaxial dislocation was reduced by using partial odontoidectomy via a video-assisted transcervical approach and maintained with posterior polyaxial screw-rod constructs and an autograft. Neurological status improved immediately after surgery, and the patient recovered completely after 1 year. Posterior fusion followed by closed reduction is the superior strategy for posterior atlantoaxial dislocation without odontoid fracture, according to literature. But for cases with severe neurological deficit, open reduction may be the safest choice to avoid the lethal complication of overdistraction of the spinal cord. Also, open reduction and posterior srew-rod fixation are safe and convenient strategies in dealing with traumatic posterior atlantoaxial dislocation patients with neurological deficit. PMID:26512572

  13. Statistics of dislocation pinning at localized obstacles

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, A. [S. N. Bose National Centre for Basic Sciences, Salt Lake, Kolkata 700098 (India); Bhattacharya, M., E-mail: mishreyee@vecc.gov.in; Barat, P. [Variable Energy Cyclotron Centre, 1/AF Bidhannagar, Kolkata 700064 (India)

    2014-10-14

    Pinning of dislocations at nanosized obstacles like precipitates, voids, and bubbles is a crucial mechanism in the context of phenomena like hardening and creep. The interaction between such an obstacle and a dislocation is often studied at fundamental level by means of analytical tools, atomistic simulations, and finite element methods. Nevertheless, the information extracted from such studies cannot be utilized to its maximum extent on account of insufficient information about the underlying statistics of this process comprising a large number of dislocations and obstacles in a system. Here, we propose a new statistical approach, where the statistics of pinning of dislocations by idealized spherical obstacles is explored by taking into account the generalized size-distribution of the obstacles along with the dislocation density within a three-dimensional framework. Starting with a minimal set of material parameters, the framework employs the method of geometrical statistics with a few simple assumptions compatible with the real physical scenario. The application of this approach, in combination with the knowledge of fundamental dislocation-obstacle interactions, has successfully been demonstrated for dislocation pinning at nanovoids in neutron irradiated type 316-stainless steel in regard to the non-conservative motion of dislocations. An interesting phenomenon of transition from rare pinning to multiple pinning regimes with increasing irradiation temperature is revealed.

  14. Palmar dislocation of scaphoid and lunate

    Directory of Open Access Journals (Sweden)

    Khalid Koulali Idrissi

    2011-11-01

    Full Text Available A palmar dislocation of scaphoid and lunate is uncommon. We have found only 19 reported cases in the literature. We reported a simultaneous, divergent dislocation. The closed reduction followed by percutaneous pinning has given a good result without avascular necrosis of any carpal bone.

  15. Interactions between Dislocations and Grain Boundaries

    NARCIS (Netherlands)

    Soer, Wouter Anthon

    2006-01-01

    Dislocations (line defects) and grain boundaries (planar defects) are two types of lattice defects that are crucial to the deformation behavior of metals. Permanent deformation of a crystalline material is microscopically associated with the nucleation and propagation of dislocations, and extensive

  16. Magnetisation of magnetite nanoparticles medium with dipol-dipol interaction

    International Nuclear Information System (INIS)

    Ali-zade, R. A.

    2005-01-01

    Full text: Magnetisation expression for magnetite nanoparticles medium with dipo-dipol interaction has been obtained. We suggested, that energy magnetic dipol-dipol interaction of magnetite nanopaticles is determined by: E d-d = - m 2 /4πμ 0 r 3 (cth x -1/x) 2 where x=mH/kT. This expression has been substituted in statistical sum of magnetite nanoparticles medium. Obtained statistical sum consists the production of two statistical sums. The first statistical sum described non-interacting magnetite nanoparticle medium and from this is obtained Langevan equation. Second statistical sum is: Z 2 -∫exp(Σm 2 /4π 0 r 3 (cth x -1/x) 2 ) dΩ 2 . The second statistical sum has been expanded in Taylor's set and taken into consideration first two terms. Integration has been carried out over all volume. In this case take into account that, number twice interactions of magnetite nanoparticles in unit volume is equal to N(N-1)/2 at N>>1 to N 2 /2. We obtain expressions for magnetisation and initial magnetic susceptibility of interacting magnetite nanoparticles medium take into account that Φ=-kT ln Z, M=-dΦ/dH, χ=dM/dH: M=M Sφm (cth x -1/x)+ 1/3 M S 2 φ m 2 (1μ 0 H) ln(VM S /kT).(cth x -1/x)(-xcsch 2 x+1/x) χ 0 =1/3 (m/kT)+ 1/27 M S 2 φ m 2 (1μ 0 )ln(VM S /kT).(m/kT) 2 . Second term in the magnetisation is sufficient at weak and middle magnetic fields. At large magnetic fields, it leads to zero. The second term of magnetisation has maximum at x=1.566. The values of experimental and calculated magnetic field corresponding to magnetisation maximum for magnetite nanoparticles medium (mean diameter of nanoparticle is 9.4 nm) are 1.19 10 4 A/m and 1.25 10 4 A/m respectively. Magnetic dipol-dipol interaction influence to magnetisation of magnetite nanoparticles. Magnetite nanoparticles lined along external magnetic fields line and formatted chains. Magnetisation of medium occurs by the 'parallel' mechanism method magnetisation of chains

  17. Estimation of dislocations density and distribution of dislocations during ECAP-Conform process

    Science.gov (United States)

    Derakhshan, Jaber Fakhimi; Parsa, Mohammad Habibi; Ayati, Vahid; Jafarian, Hamidreza

    2018-01-01

    Dislocation density of coarse grain aluminum AA1100 alloy (140 µm) that was severely deformed by Equal Channel Angular Pressing-Conform (ECAP-Conform) are studied at various stages of the process by electron backscattering diffraction (EBSD) method. The geometrically necessary dislocations (GNDs) density and statistically stored dislocations (SSDs) densities were estimate. Then the total dislocations densities are calculated and the dislocation distributions are presented as the contour maps. Estimated average dislocations density for annealed of about 2×1012 m-2 increases to 4×1013 m-2 at the middle of the groove (135° from the entrance), and they reach to 6.4×1013 m-2 at the end of groove just before ECAP region. Calculated average dislocations density for one pass severely deformed Al sample reached to 6.2×1014 m-2. At micrometer scale the behavior of metals especially mechanical properties largely depend on the dislocation density and dislocation distribution. So, yield stresses at different conditions were estimated based on the calculated dislocation densities. Then estimated yield stresses were compared with experimental results and good agreements were found. Although grain size of material did not clearly change, yield stress shown intensive increase due to the development of cell structure. A considerable increase in dislocations density in this process is a good justification for forming subgrains and cell structures during process which it can be reason of increasing in yield stress.

  18. Effects of dislocations on polycrystal anelasticity

    Science.gov (United States)

    Sasaki, Y.; Takei, Y.; McCarthy, C.; Suzuki, A.

    2017-12-01

    Effects of dislocations on the seismic velocity and attenuation have been poorly understood, because only a few experimental studies have been performed [Guéguen et al., 1989; Farla et al., 2012]. By using organic borneol as a rock analogue, we measured dislocation-induced anelasticity accurately over a broad frequency range. We first measured the flow law of borneol aggregates by uniaxial compression tests under a confining pressure of 0.8 MPa. A transition from diffusion creep (n = 1) to dislocation creep (n = 5) was captured at about σ = 1 MPa (40°C-50°C). After deforming in the dislocation creep regime, sample microstructure showed irregular grain shape consistent with grain boundary migration. Next, we conducted three creep tests at σ = 0.27 MPa (diffusion creep regime), σ = 1.3 MPa and σ = 1.9 MPa (dislocation creep regime) on the same sample in increasing order, and measured Young's modulus E and attenuation Q-1 after each creep test by forced oscillation tests. The results show that as σ increased, E decreased and Q-1 increased. These changes induced by dislocations, however, almost fully recovered during the forced oscillation tests performed for about two weeks under a small stress (σ = 0.27 MPa) due to the dislocation recovery (annihilation). In order to constrain the time scale of the dislocation-induced anelastic relaxation, we further measured Young's modulus E at ultrasonic frequency before and after the dislocation creep and found that E at 106 Hz is not influenced by dislocations. Because E at 100 Hz is reduced by dislocations by 10%, the dislocation-induced anelastic relaxation occurs mostly between 102-106 Hz which is at a higher frequency than grain-boundary-induced anelasticity. To avoid dislocation recovery during the anelasticity measurement, we are now trying to perform an in-situ measurement of anelasticity while simultaneously deforming under a high stress associated with dislocation creep. The combination of persistent creep

  19. Prototype and proposed ISABELLE dipoles

    International Nuclear Information System (INIS)

    McInturff, A.D.; Sampson, W.B.; Robins, K.E.; Dahl, P.F.; Damm, R.

    1977-01-01

    Data are presented on the latest dipole prototypes to update the operational parameters possible for ISABELLE. This data base will constantly expand until the start of construction of the storage rings. The data will include field quality, stray field magnitudes, quench temperature and propagation times, protection capabilities singly and in multiple units, maximum central fields obtained and training behavior. Performance of the dipoles versus temperature and mode of refrigeration will be discussed. The single layer cosine theta turns distribution coils' parameters are better than those required for the operation of the 200 x 200 GeV version of ISABELLE. The double layer prototype has exceeded the magnetic field performance and two dimensional quality of field needed for the 400 x 400 GeV version of ISABELLE

  20. Dynamic aspects of dislocation motion: atomistic simulations

    International Nuclear Information System (INIS)

    Bitzek, Erik; Gumbsch, Peter

    2005-01-01

    Atomistic simulations of accelerating edge and screw dislocations were carried out to study the dynamics of dislocations in a face centered cubic metal. Using two different embedded atom potentials for nickel and a simple slab geometry, the Peierls stress, the effective mass, the line tension and the drag coefficient were determined. A dislocation intersecting an array of voids is used to study dynamic effects in dislocation-obstacle interactions. A pronounced effect caused by inertial overshooting is found. A dynamic line tension model is developed which reproduces the simulation results. The model can be used to easily estimate the magnitude of inertial effects in the interaction of dislocations with localized obstacles for different obstacle strengths, -spacings and temperatures

  1. Rules for Forest Interactions between Dislocations

    International Nuclear Information System (INIS)

    Wickham, L. K.; Schwarz, K. W.; Stoelken, J. S.

    1999-01-01

    The dynamical interactions of dislocations existing on intersecting glide planes have been investigated using numerical simulations based on isotropic linear elastic theory. It is found that such dislocations either repel, attract and form growing junctions, or attract and form bound crossed states. Which of these occurs can be predicted from a surprisingly simple analysis of the initial configurations. The outcome is determined primarily by the angles which the dislocations initially make with the glide-plane intersection edge, and is largely independent of the initial distance between the dislocations, their initial curvature, or ambient applied stresses. The results provide a rule for dealing with forest interactions within the context of large multiple-dislocation computations. (c) 1999 The American Physical Society

  2. Microwave conductivity and spin resonance of Si- nK centers at dislocation dipoles in silicon

    Science.gov (United States)

    Konchits, A. A.; Shanina, B. D.

    1995-11-01

    Non-resonance microwave absorption (NRMA) due to microwave conductivity (MC) of Czochralski-grown silicon crystal has been studied. The temperature dependence of the MC was measured in the temperature range from 1.7 to 40 K in darkness as well as under the interband light. Exponential growth of the MC in a low temperature range is described within the extended one-dimensional Hubbard model for the case of an arbitrary filled band. The activation energy of electron hopping motion in darkness is found to be similar to that in amorphous silicon (0.4 meV), although, under light its value is significantly larger (12 meV). The logarithmic law is revealed for the MC decay. The value of its time constant τ0 at T = 4.2 K changes with the light intensity I from 4 to 57 s, so τ0 is proportional to I-1. The exponential recovery process at T = 4.2 K goes rather slowly, with τ1 in interval from 0.4 to 3.11 min depending on the location of the donor levels in a band gap. It is shown that the linear law connects the dependence of the TD-2 EPR intensity increase and the Si- nK EDSR intensity decrease versus the MC decay under continuous illumination.

  3. Aperture measurements with AC dipole

    CERN Document Server

    Fuster Martinez, Nuria; Dilly, Joschua Werner; Nevay, Laurence James; Bruce, Roderik; Tomas Garcia, Rogelio; Redaelli, Stefano; Persson, Tobias Hakan Bjorn; CERN. Geneva. ATS Department

    2018-01-01

    During the MDs performed on the 15th of September and 29th of November 2017, we measured the LHC global aperture at injection with a new AC dipole method as well as using the Transverse Damper (ADT) blow-up method used during the 2017 LHC commissioning for benchmarking. In this note, the MD procedure is presented as well as the analysis of the comparison between the two methods. The possible benefits of the new method are discussed.

  4. Electric Dipole Moments of Hadrons

    OpenAIRE

    Wirzba, Andreas

    2016-01-01

    A nonzero electric dipole moment (EDM) of the neutron, proton, deuteron, helion or any finite system necessarily involves the breaking of a symmetry, either by the presence of external fields (leading to the case of induced EDMs) or explicitly by the breaking of the discrete parity and time-reflection symmetries in the case of permanent EDMs. Recent - and in the case of the deuteron even unpublished - results for the relevant matrix elements of nuclear EDM operators are presented and the rel...

  5. Dipole-induced exchange bias.

    Science.gov (United States)

    Torres, Felipe; Morales, Rafael; Schuller, Ivan K; Kiwi, Miguel

    2017-11-09

    The discovery of dipole-induced exchange bias (EB), switching from negative to positive sign, is reported in systems where the antiferromagnet and the ferromagnet are separated by a paramagnetic spacer (AFM-PM-FM). The magnitude and sign of the EB is determined by the cooling field strength and the PM thickness. The same cooling field yields negative EB for thin spacers, and positive EB for thicker ones. The EB decay profile as a function of the spacer thickness, and the change of sign, are attributed to long-ranged dipole coupling. Our model, which accounts quantitatively for the experimental results, ignores the short range interfacial exchange interactions of the usual EB theories. Instead, it retains solely the long range dipole field that allows for the coupling of the FM and AFM across the PM spacer. The experiments allow for novel switching capabilities of long range EB systems, while the theory allows description of the structures where the FM and AFM are not in atomic contact. The results provide a new approach to design novel interacting heterostructures.

  6. Influence of mobile dislocations on phase separation in binary alloys

    International Nuclear Information System (INIS)

    Haataja, Mikko; Leonard, Francois

    2004-01-01

    We introduce a continuum model to describe the phase separation of a binary alloy in the presence of mobile dislocations. The kinetics of the local composition and dislocation density are coupled through their elastic fields. We show both analytically and numerically that mobile dislocations modify the standard spinodal decomposition process, and lead to several regimes of growth. Depending on the dislocation mobility and observation time, the phase separation may be accelerated, decelerated, or unaffected by mobile dislocations. For any finite dislocation mobility, we show that the domain growth rate asymptotically becomes independent of the dislocation mobility, and is faster than the dislocation-free growth rate

  7. Static dipole polarizabilities of Scn (n ≤ 15) clusters

    International Nuclear Information System (INIS)

    Xi-Bo, Li; Jiang-Shan, Luo; Wei-Dong, Wu; Yong-Jian, Tang; Hong-Yan, Wang; Yun-Dong, Guo

    2009-01-01

    The static dipole polarizabilities of scandium clusters with up to 15 atoms are determined by using the numerically finite field method in the framework of density functional theory. The electronic effects on the polarizabilities are investigated for the scandium clusters. We examine a large highest occupied molecular orbital — the lowest occupied molecular orbital (HOMO–LUMO) gap of a scandium cluster usually corresponds to a large dipole moment. The static polarizability per atom decreases slowly and exhibits local minimum with increasing cluster size. The polarizability anisotropy and the ratio of mean static polarizability to the HOMO–LUMO gap can also reflect the cluster stability. The polarizability of the scandium cluster is partially related to the HOMO–LUMO gap and is also dependent on geometrical characteristics. A strong correlation between the polarizability and ionization energy is observed. (atomic and molecular physics)

  8. Dislocation-induced stress in polycrystalline materials: mesoscopic simulations in the dislocation density formalism

    Science.gov (United States)

    Berkov, D. V.; Gorn, N. L.

    2018-06-01

    In this paper we present a simple and effective numerical method which allows a fast Fourier transformation-based evaluation of stress generated by dislocations with arbitrary directions and Burgers vectors if the (site-dependent) dislocation density is known. Our method allows the evaluation of the dislocation stress using a rectangular grid with shape-anisotropic discretization cells without employing higher multipole moments of the dislocation interaction coefficients. Using the proposed method, we first simulate the stress created by relatively simple non-homogeneous distributions of vertical edge and so-called ‘mixed’ dislocations in a disk-shaped sample, which is necessary to understand the dislocation behavior in more complicated systems. The main part of our research is devoted to the stress distribution in polycrystalline layers with the dislocation density rapidly varying with the distance to the layer bottom. Considering GaN as a typical example of such systems, we investigate dislocation-induced stress for edge and mixed dislocations, having random orientations of Burgers vectors among crystal grains. We show that the rapid decay of the dislocation density leads to many highly non-trivial features of the stress distributions in such layers and study in detail the dependence of these features on the average grain size. Finally we develop an analytical approach which allows us to predict the evolution of the stress variance with the grain size and compare analytical predictions with numerical results.

  9. Frenkel defect absorption on dislocations and dislocation discharge rate. Modeling determination of the absorption zone

    International Nuclear Information System (INIS)

    Mikhlin, Eh.Ya.

    1988-01-01

    A situation connected with the fact that evaluations of dislocation discharge strength which somehow or other are based on the elasticity theory in the dislocation nucleus or near it, do not lead to results complying with experimental data, is discussed. Bases of the alternative approach to this problem consisting in direct investigation into the process of Frenkel defect absorption on dislocation by its computerized simulation at the microscopic level are also presented. Methods of investigation and results are described using α dislocation in iron-alpha as an example. The concept of zones of vacancy and interstitial atom absorption on dislocation is discussed. It is shown that a spontaneous transition, performed by any of these defects near a dislocation is not always identical to absorption and usually appears to be only a part of a multistage process leading to the defect disappearance. Potential relief characteristics for vacancy movement near the dislocation are found. An area wide enough in a transverse direction is found around the dislocation. Vacncies reaching this area can be easily transported to places of their disappearance. Therefore the vacancy entry to this area is equivalent to the absorption. the procedure of simulating the atomic structure of a crystallite containing a dislocation with a step is described. Positions from which these defects perform spontaneous transitions, reaching the disappearance places are found on the dislocation near the step

  10. RHIC spin flipper AC dipole controller

    Energy Technology Data Exchange (ETDEWEB)

    Oddo, P.; Bai, M.; Dawson, C.; Gassner, D.; Harvey, M.; Hayes, T.; Mernick, K.; Minty, M.; Roser, T.; Severino, F.; Smith, K.

    2011-03-28

    The RHIC Spin Flipper's five high-Q AC dipoles which are driven by a swept frequency waveform require precise control of phase and amplitude during the sweep. This control is achieved using FPGA based feedback controllers. Multiple feedback loops are used to and dynamically tune the magnets. The current implementation and results will be presented. Work on a new spin flipper for RHIC (Relativistic Heavy Ion Collider) incorporating multiple dynamically tuned high-Q AC-dipoles has been developed for RHIC spin-physics experiments. A spin flipper is needed to cancel systematic errors by reversing the spin direction of the two colliding beams multiple times during a store. The spin flipper system consists of four DC-dipole magnets (spin rotators) and five AC-dipole magnets. Multiple AC-dipoles are needed to localize the driven coherent betatron oscillation inside the spin flipper. Operationally the AC-dipoles form two swept frequency bumps that minimize the effect of the AC-dipole dipoles outside of the spin flipper. Both AC bumps operate at the same frequency, but are phase shifted from each other. The AC-dipoles therefore require precise control over amplitude and phase making the implementation of the AC-dipole controller the central challenge.

  11. Ultrasonic Study of Dislocation Dynamics in Lithium -

    Science.gov (United States)

    Han, Myeong-Deok

    1987-09-01

    Experimental studies of dislocation dynamics in LiF single crystals, using ultrasonic techniques combined with dynamic loading, were performed to investigate the time evolution of the plastic deformation process under a short stress pulse at room temperature, and the temperature dependence of the dislocation damping mechanism in the temperature range 25 - 300(DEGREES)K. From the former, the time dependence of the ultrasonic attenuation was understood as resulting from dislocation multiplication followed by the evolution of mobile dislocations to immobile ones under large stress. From the latter, the temperature dependence of the ultrasonic attenuation was interpreted as due to the motion of the dislocation loops overcoming the periodic Peierls potential barrier in a manner analogous to the motion of a thermalized sine-Gordon chain under a small stress. The Peierls stress obtained from the experimental results by application of Seeger's relaxation model with exponential dislocation length distribution was 4.26MPa, which is consistent with the lowest stress for the linear relation between the dislocation velocity and stress observed by Flinn and Tinder.

  12. Bilateral posterior crystalline lens dislocations in an otherwise healthy child

    Directory of Open Access Journals (Sweden)

    AlShehri, Omar A.

    2017-10-01

    Full Text Available Introduction: Ectopia lentis is defined as a crystalline lens displacement, either partially or completely, due to zonular abnormalities. It can be a result of trauma, hereditary ocular disease, or part of systemic diseases, like Marfan syndrome and homocystinuria.Case description: We report a case of a medically free 16-year-old girl, who was referred to our hospital complaining of poor vision and a squint in both eyes since childhood. Her history included a traffic accident when she was one-year-old. She was previously diagnosed with alternating esotropia, which was treated with glasses, alternating patching, and bilateral Botox injections. On examination, she had a visual acuity of 6/7.5 with correction in the right eye and 6/6 with correction in the left eye. She had an esotropia of 60 prism diopters, which was partially corrected to 40 prism diopters for near and distance vision. Fundus examination showed myopic changes in each eye and dislocated lenses in the posterior pole at 6 o’clock. Our case was stable, so we used conservative management with contact lenses.Conclusion: Bilateral posterior lens dislocation is very rare. A proper examination is important and early diagnosis can prevent serious complications, such as retinal detachment or pupillary block glaucoma.

  13. Thermodynamic theory of dislocation-enabled plasticity

    International Nuclear Information System (INIS)

    Langer, J. S.

    2017-01-01

    The thermodynamic theory of dislocation-enabled plasticity is based on two unconventional hypotheses. The first of these is that a system of dislocations, driven by external forces and irreversibly exchanging heat with its environment, must be characterized by a thermodynamically defined effective temperature that is not the same as the ordinary temperature. The second hypothesis is that the overwhelmingly dominant mechanism controlling plastic deformation is thermally activated depinning of entangled pairs of dislocations. This paper consists of a systematic reformulation of this theory followed by examples of its use in analyses of experimentally observed phenomena including strain hardening, grain-size (Hall-Petch) effects, yielding transitions, and adiabatic shear banding.

  14. Atomic structure of screw dislocations intersecting the Au(111) surface: A combined scanning tunneling microscopy and molecular dynamics study

    DEFF Research Database (Denmark)

    Engbæk, Jakob; Schiøtz, Jakob; Dahl-Madsen, Bjarke

    2006-01-01

    The atomic-scale structure of naturally occurring screw dislocations intersecting a Au(111) surface has been investigated both experimentally by scanning tunneling microscopy (STM) and theoretically using molecular dynamics (MD) simulations. The step profiles of 166 dislocations were measured using...... STM. Many of them exhibit noninteger step-height plateaus with different widths. Clear evidence was found for the existence of two different populations at the surface with distinct (narrowed or widened) partial-splitting widths. All findings are fully confirmed by the MD simulations. The MD...... simulations extend the STM-, i.e., surface-, investigation to the subsurface region. Due to this additional insight, we can explain the different partial-splitting widths as the result of the interaction between the partial dislocations and the surface....

  15. Distribution of distances between dislocations in different types of dislocation substructures in deformed Cu-Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Trishkina, L., E-mail: trishkina.53@mail.ru; Zboykova, N.; Koneva, N., E-mail: koneva@tsuab.ru; Kozlov, E. [Tomsk State University of Architecture and Building, 2 Solyanaya St., Tomsk, 634003 (Russian Federation); Cherkasova, T. [Tomsk State University of Architecture and Building, 2 Solyanaya St., Tomsk, 634003 (Russian Federation); National Research Tomsk Polytechnic University, 50 Lenin Ave., Tomsk, 634050 (Russian Federation)

    2016-01-15

    The aim of the investigation was the determination of the statistic description of dislocation distribution in each dislocation substructures component forming after different deformation degrees in the Cu-Al alloys. The dislocation structures were investigated by the transmission diffraction electron microscopy method. In the work the statistic description of distance distribution between the dislocations, dislocation barriers and dislocation tangles in the deformed Cu-Al alloys with different concentration of Al and test temperature at the grain size of 100 µm was carried out. It was established that the above parameters influence the dislocation distribution in different types of the dislocation substructures (DSS): dislocation chaos, dislocation networks without disorientation, nondisoriented and disoriented cells, in the walls and inside the cells. The distributions of the distances between dislocations in the investigated alloys for each DSS type formed at certain deformation degrees and various test temperatures were plotted.

  16. Distribution of distances between dislocations in different types of dislocation substructures in deformed Cu-Al alloys

    Science.gov (United States)

    Trishkina, L.; Cherkasova, T.; Zboykova, N.; Koneva, N.; Kozlov, E.

    2016-01-01

    The aim of the investigation was the determination of the statistic description of dislocation distribution in each dislocation substructures component forming after different deformation degrees in the Cu-Al alloys. The dislocation structures were investigated by the transmission diffraction electron microscopy method. In the work the statistic description of distance distribution between the dislocations, dislocation barriers and dislocation tangles in the deformed Cu-Al alloys with different concentration of Al and test temperature at the grain size of 100 µm was carried out. It was established that the above parameters influence the dislocation distribution in different types of the dislocation substructures (DSS): dislocation chaos, dislocation networks without disorientation, nondisoriented and disoriented cells, in the walls and inside the cells. The distributions of the distances between dislocations in the investigated alloys for each DSS type formed at certain deformation degrees and various test temperatures were plotted.

  17. Electric dipole polarizability from first principles calculations

    International Nuclear Information System (INIS)

    Miorelli, M.; University of British Columbia, Vancouver, BC; Bacca, S.; University of Manitoba; Barnea, N.

    2016-01-01

    The electric dipole polarizability quantifies the low-energy behavior of the dipole strength and is related to critical observables such as the radii of the proton and neutron distributions. Its computation is challenging because most of the dipole strength lies in the scattering continuum. In our paper we combine integral transforms with the coupled-cluster method and compute the dipole polarizability using bound-state techniques. Furthermore, employing different interactions from chiral effective field theory, we confirm the strong correlation between the dipole polarizability and the charge radius, and study its dependence on three-nucleon forces. Finally, we find good agreement with data for the 4 He, 40 Ca, and 16 O nuclei, and predict the dipole polarizability for the rare nucleus 22 O.

  18. Canonical Quantization of Crystal Dislocation and Electron-Dislocation Scattering in an Isotropic Media

    Science.gov (United States)

    Li, Mingda; Cui, Wenping; Dresselhaus, M. S.; Chen, Gang; MIT Team; Boston College Team

    Crystal dislocations govern the plastic mechanical properties of materials but also affect the electrical and optical properties. However, a fundamental and decent quantum-mechanical theory of dislocation remains undiscovered for decades. Here we present an exact and manageable Hamiltonian theory for both edge and screw dislocation line in an isotropic media, where the effective Hamiltonian of a single dislocation line can be written in a harmonic-oscillator-like form, with closed-form quantized 1D phonon-like excitation. Moreover a closed-form, position dependent electron-dislocation coupling strength is obtained, from which we obtained good agreement of relaxation time when comparing with classical results. This Hamiltonian provides a platform to study the effect of dislocation to materials' non-mechanical properties from a fundamental Hamiltonian level.

  19. "Conjugate channeling" effect in dislocation core diffusion: carbon transport in dislocated BCC iron.

    Science.gov (United States)

    Ishii, Akio; Li, Ju; Ogata, Shigenobu

    2013-01-01

    Dislocation pipe diffusion seems to be a well-established phenomenon. Here we demonstrate an unexpected effect, that the migration of interstitials such as carbon in iron may be accelerated not in the dislocation line direction ξ, but in a conjugate diffusion direction. This accelerated random walk arises from a simple crystallographic channeling effect. c is a function of the Burgers vector b, but not ξ, thus a dislocation loop possesses the same everywhere. Using molecular dynamics and accelerated dynamics simulations, we further show that such dislocation-core-coupled carbon diffusion in iron has temperature-dependent activation enthalpy like a fragile glass. The 71° mixed dislocation is the only case in which we see straightforward pipe diffusion that does not depend on dislocation mobility.

  20. CERN LHC dipole prototype success

    International Nuclear Information System (INIS)

    Anon.

    1994-01-01

    In a crash programme, the first prototype superconducting dipole magnet for CERN's LHC protonproton collider was successfully powered for the first time at CERN on 14 April, eventually sailing to 9T, above the 8.65T nominal LHC field, before quenching for the third time. The next stage is to install the delicate measuring system for making comprehensive magnetic field maps in the 10 m long, 50 mm diameter twin-apertures of the magnet. These measurements will check that the required LHC field quality has been achieved at both the nominal and injection fields

  1. Alternative dipole magnets for ISABELLE

    Science.gov (United States)

    Taylor, C.; Althaus, R.; Caspi, S.; Gilbert, W.; Hassenzahl, W. V.; Meuser, R.; Rechen, J.; Warren, R.

    1982-05-01

    A dipole magnet, intended as a possible alternative for the ISABELLE main ring magnet, was designed. Three layers of FNAL Doubler/Saver conductor were used. Two 1.3-m-long models were built and tested, both with and without an iron core, and in both helium I and helium II. The training behavior, cyclic energy loss, point of quench initiation, and quench velocity were determined. A central field of 6.5 tesla was obtained in He I (4.4 K), and 7.6 tesla in He II (1.8K).

  2. Electric and Magnetic Dipole Moments

    CERN Document Server

    CERN. Geneva

    2005-01-01

    The stringent limit on the electric dipole moment of the neutron forced the issue on the strong CP-problem. The most elegant solution of which is the axion field proposed by Peccei and Quinn. The current limit on the QCD parameter theta coming from the limit on the neutron EDM is of order 10-10. I am going to describe the present status on the neutron EDM searches and further prospects on getting down to theta_qcd sensitivity of 10-13 with the new deuteron EDM in storage rings proposal. For completeness the current status and prospects of the muon g-2 experiment will also be given.

  3. The Muon Electric Dipole Moment

    OpenAIRE

    Barger, Vernon; Kao, Chung; Das, Ashok

    1997-01-01

    The electric dipole moment of the muon ($d_\\mu$) is evaluated in a two Higgs doublet model with a softly broken discrete symmetry. For $\\tan\\beta \\equiv |v_2|/|v_1| \\sim 1$, contributions from two loop diagrams involving the $t$ quark and the $W$ boson dominate; while for $\\tan\\beta \\gsim 10$, contributions from two loop diagrams involving the $b$ quark and the $\\tau$ lepton are dominant. For $8 \\gsim \\tan\\beta \\gsim 4$, significant cancellation occurs among the contributions from two loop di...

  4. The climb of dissociated dislocations in a quenched Cu-13.43 at.% Al alloy

    International Nuclear Information System (INIS)

    Decamps, B.; Cherns, D.; Condat, M.

    1983-01-01

    The weak-beam electron microscopy technique has been used to study the climb of dissociated dislocations in a Cu-13.43 at.% Al alloy under conditions of supersaturation of vacancies introduced by quenching. The results are similar to those obtained under electron irradiation (interstitial climb) in the same alloy (Cherns, Hirsch and Saka 1980) in that climb may proceed by the nucleation of prismatic loops on the individual partials. The nature of the loops is such as to minimize the total energy of the configuration (partial plus loop) and to maximize their edge component. Interaction with the other partial has been observed, causing the entire dislocation to climb. Additional features observed suggest that climb under quenching is initiated by the nucleation of Frank loops. The detailed configurations also enable climb by absorption of vacancies and interstitials to be distinguished. (author)

  5. Permanent Magnet Dipole for DIRAC Design Report

    CERN Document Server

    Vorozhtsov, Alexey

    2012-01-01

    Two dipole magnets including one spare unit are needed for the for the DIRAC experiment. The proposed design is a permanent magnet dipole. The design based on Sm2Co17 blocks assembled together with soft ferromagnetic pole tips. The magnet provides integrated field strength of 24.6 10-3 T×m inside the aperture of 60 mm. This Design Report summarizes the main magnetic and mechanic design parameters of the permanent dipole magnets.

  6. Electric dipole moment of diatomic molecules

    International Nuclear Information System (INIS)

    Rosato, A.

    1983-01-01

    The electric dipole moment of some diatomic molecules is calculated using the Variational Cellular Method. The results obtained for the molecules CO, HB, HF and LiH are compared with other calculations and with experimental data. It is shown that there is strong dependence of the electric dipole moment with respect to the geometry of the cells. It is discussed the possibility of fixing the geometry of the problem by giving the experimental value of the dipole moment. (Author) [pt

  7. SSC collider dipole magnet end mechanical design

    International Nuclear Information System (INIS)

    Delchamps, S.W.; Bossert, R.C.; Carson, J.; Ewald, K.; Fulton, H.; Kerby, J.; Koska, W.; Strait, J.; Wake, M.; Leung, K.K.

    1991-01-01

    This paper describes the mechanical design of the ends of Superconducting Super Collider dipole magnets to be constructed and tested at Fermilab. Coil end clamps, end yoke configuration, and end plate design are discussed. Loading of the end plate by axial Lorentz forces is discussed. Relevant data from 40 mm and 50 mm aperture model dipole magnets built and tested at Fermilab are presented. In particular, the apparent influence of end clamp design on the quench behavior of model SSC dipoles is described

  8. Electric dipole moment of diatomic molecules

    International Nuclear Information System (INIS)

    Rosato, A.

    1983-01-01

    The electric dipole moment of some diatomic molecules is calculated using the Variational Cellular Method. The results obtained for the CO, HB, HF and LiH molecules are compared with other calculations and with experimental data. It is shown that there is strong dependence of the electric dipole moment with respect to the geometry of the cells. The possibility of fixing the geometry of the problem by giving the experimental value of the dipole moment is discussed. (Author) [pt

  9. W-boson electric dipole moment

    International Nuclear Information System (INIS)

    He, X.; McKellar, B.H.J.

    1990-01-01

    The W-boson electric dipole moment is calculated in the SU(3) C xSU(2) L xU(1) Y model with several Higgs-boson doublets. Using the constraint on the CP-violating parameters from the experimental upper bound of the neutron electric dipole moment, we find that the W-boson electric dipole moment is constrained to be less than 10 -4

  10. Domain configurations in dislocations embedded hexagonal manganite systems: From the view of graph theory

    Science.gov (United States)

    Cheng, Shaobo; Zhang, Dong; Deng, Shiqing; Li, Xing; Li, Jun; Tan, Guotai; Zhu, Yimei; Zhu, Jing

    2018-04-01

    Topological defects and their interactions often arouse multiple types of emerging phenomena from edge states in Skyrmions to disclination pairs in liquid crystals. In hexagonal manganites, partial edge dislocations, a prototype topological defect, are ubiquitous and they significantly alter the topologically protected domains and their behaviors. Herein, combining electron microscopy experiment and graph theory analysis, we report a systematic study of the connections and configurations of domains in this dislocation embedded system. Rules for domain arrangement are established. The dividing line between domains, which can be attributed by the strain field of dislocations, is accurately described by a genus model from a higher dimension in the graph theory. Our results open a door for the understanding of domain patterns in topologically protected multiferroic systems.

  11. The dipole-dipole dispersion forces for small, intermediate and large distances

    International Nuclear Information System (INIS)

    Antonio, J.C.

    1986-10-01

    An improved expression is obtained for the dipole-dipole London dispersion force between closed shell atoms for small, intermediate and large distances compared with their linear dimensions. (Author) [pt

  12. Derivation of the electric dipole--dipole interaction as an electric hyperfine interaction

    International Nuclear Information System (INIS)

    Parker, G.W.

    1986-01-01

    The electric dipole--dipole interaction is derived by assuming that the electron and proton in hydrogen have intrinsic electric dipole moments that interact to give an electric hyperfine interaction. The electric field at the proton due to the electron's presumed dipole moment then gives rise to a contact type term for l = 0 and the normal dipole--dipole term for lnot =0. When combined with our previous derivation of the magnetic hyperfine interaction [Am. J. Phys. 52, 36 (1984)], which used a similar approach, these derivations provide a unified treatment of the interaction of electric and magnetic dipoles. As an application of these results, the product of the electron's and proton's dipole moments is estimated to be less than 10 -29 e 2 cm 2

  13. Enhanced and tunable electric dipole-dipole interactions near a planar metal film

    Science.gov (United States)

    Zhou, Lei-Ming; Yao, Pei-Jun; Zhao, Nan; Sun, Fang-Wen

    2017-08-01

    We investigate the enhanced electric dipole-dipole interaction of surface plasmon polaritons (SPPs) supported by a planar metal film waveguide. By taking two nitrogen-vacancy (NV) center electric dipoles in diamond as an example, both the coupling strength and collective relaxation of two dipoles are studied with the numerical Green Function method. Compared to two-dipole coupling on a planar surface, metal film provides stronger and tunable coupling coefficients. Enhancement of the interaction between coupled NV center dipoles could have applications in both quantum information and energy transfer investigation. Our investigation provides systematic results for experimental applications based on a dipole-dipole interaction mediated with SPPs on a planar metal film.

  14. coccygectomy for chronic, symptomatic coccygeal dislocation

    African Journals Online (AJOL)

    evidence revealed anterior dislocation of terminal two coccygeal vertebrae ... a prominent terminal coccygeal curvature. The patient presented during her first visit with. CT SCAN .... physiotherapy, modified wedge-shaped coccygeal foam pads ...

  15. How to introduce the magnetic dipole moment

    International Nuclear Information System (INIS)

    Bezerra, M; Kort-Kamp, W J M; Cougo-Pinto, M V; Farina, C

    2012-01-01

    We show how the concept of the magnetic dipole moment can be introduced in the same way as the concept of the electric dipole moment in introductory courses on electromagnetism. Considering a localized steady current distribution, we make a Taylor expansion directly in the Biot-Savart law to obtain, explicitly, the dominant contribution of the magnetic field at distant points, identifying the magnetic dipole moment of the distribution. We also present a simple but general demonstration of the torque exerted by a uniform magnetic field on a current loop of general form, not necessarily planar. For pedagogical reasons we start by reviewing briefly the concept of the electric dipole moment. (paper)

  16. Dipoles on a Two-leg Ladder

    DEFF Research Database (Denmark)

    Gammelmark, Søren; Zinner, Nikolaj Thomas

    2013-01-01

    We study polar molecules with long-range dipole-dipole interactions confined to move on a two-leg ladder for different orientations of the molecular dipole moments with respect to the ladder. Matrix product states are employed to calculate the many-body ground state of the system as function...... that there is a critical angle at which ordering disappears. This angle is slightly larger than the angle at which the dipoles are non-interacting along a single leg. This behavior should be observable using current experimental techniques....

  17. Mechanisms for decoration of dislocations by small dislocation loops under cascade damage conditions

    DEFF Research Database (Denmark)

    Trinkaus, H.; Singh, B.N.; Foreman, A.J.E.

    1997-01-01

    . This effect may arise as a result of either (a) migration and enhanced agglomeration of single SIAs in the form of loops in the strain field of the dislocation or (b) glide and trapping of SIA loops (produced directly in the cascades) in the strain field of the dislocation, In the present paper, both...... of these possibilities are examined. It is shown that the strain field of the dislocation causes a SIA depletion in the compressive as well as in the dilatational region resulting in a reduced rather than enhanced agglomeration of SIAs. (SIA depletion may, however, induce enhanced vacancy agglomeration near dislocations...

  18. The elastic properties, generalized stacking fault energy and dissociated dislocations in MgB2 under different pressure

    KAUST Repository

    Feng, Huifang

    2013-05-31

    The 〈112̄0〉 perfect dislocation in MgB2 is suggested to dissociate into two partial dislocations in an energy favorable way 〈112̄0〉 → 1/2 〈112̄0〉 + SF + 1/2 〈112̄0〉. This dissociation style is a correction of the previous dissociation 〈1000〉 → 1/3 〈11̄00〉 SF + 1/3 〈 2100〉proposed by Zhu et al. to model the partial dislocations and stacking fault observed by transmission electron microscopy. The latter dissociation results in a maximal stacking fault energy rather than a minimal one according to the generalized stacking fault energy calculated from first-principles methods. Furthermore, the elastic constants and anisotropy of MgB2 under different pressure are investigated. The core structures and mobilities of the 〈112̄0〉 dissociated dislocations are studied within the modified Peierls-Nabarro (P-N) dislocation theory. The variational method is used to solve the modified P-N dislocation equation and the Peierls stress is also determined under different pressure. High pressure effects on elastic anisotropy, core structure and Peierls stress are also presented. © 2013 Springer Science+Business Media New York.

  19. Posterior atlantoaxial dislocation without odontoid fracture

    International Nuclear Information System (INIS)

    Chaudhary, Reema; Raut, Abhijit; Chaudhary, Kshitij; Metkar, Umesh; Rathod, Ashok; Sanghvi, Darshana

    2008-01-01

    We report a case of posterior atlantoaxial dislocation without a fracture of the odontoid in a 35-year-old woman. There have been nine reported cases of similar injury in the English literature. The integrity of the transverse ligament following posterior atlantoaxial dislocations has not been well documented in these reports. In the present case, MRI revealed an intact transverse ligament, which probably contributed to the stability of the C1-C2 complex following closed reduction. (orig.)

  20. Hip dysplasia and congenital hip dislocation

    Energy Technology Data Exchange (ETDEWEB)

    Lingg, G.; Nebel, G.; von Torklus, D.

    1981-11-01

    In human genetics and orthopedics quite different answers have been given to the question of hereditary transmission and frequency of hip dysplasia in families of children with congenital hip dislocation. We therefore have made roentgenometric measurements of 110 parents of children with congenital hip dislocation. In 25% we found abnormal flat acetabulae, whereas 12% had pathologic deep hips. This may propose a new concept of morphology of congenital hip dysplasia.

  1. Isolated Proximal Tibiofibular Dislocation during Soccer

    Directory of Open Access Journals (Sweden)

    Casey Chiu

    2015-01-01

    Full Text Available Proximal tibiofibular dislocations are rarely encountered in the Emergency Department (ED. We present a case involving a man presenting to the ED with left knee pain after making a sharp left turn on the soccer field. His physical exam was only remarkable for tenderness over the lateral fibular head. His X-rays showed subtle abnormalities of the tibiofibular joint. The dislocation was reduced and the patient was discharged from the ED with orthopedic follow-up.

  2. Posterior sternoclavicular dislocation: an American football injury

    DEFF Research Database (Denmark)

    Marker, L B; Klareskov, B

    1996-01-01

    Posterior dislocation of the sternoclavicular joint is uncommon, accounting for less than 0.1% of all dislocations. Since 1824 a little more than 100 cases have been reported, and the majority in the past 20 years. A review of published reports suggests that this injury is seen particularly in co...... in connection with American football. A typical case is described. The importance of this injury is that there is often a delay in diagnosis with potentially serious complications....

  3. Transscaphoid, transcapitate, perilunate fracture dislocation (Scaphocapitate syndrome)

    International Nuclear Information System (INIS)

    Resnik, C.S.; Resnick, D.; Gelberman, R.H.

    1983-01-01

    Five cases of transscaphoid, transcapitate, perilunate fracture dislocation have been presented with a discussion of the radiologic findings, mechanism of injury, and the method of treatment. Although a total of only 23 cases have now been reported in the literature, this type of injury is probably not rare as we have seen two cases within a span of six months. It is important to recognize the radiologic features of this fracture dislocation so appropriate therapy may be instituted. (orig.)

  4. Steps and dislocations in cubic lyotropic crystals

    International Nuclear Information System (INIS)

    Leroy, S; Pieranski, P

    2006-01-01

    It has been shown recently that lyotropic systems are convenient for studies of faceting, growth or anisotropic surface melting of crystals. All these phenomena imply the active contribution of surface steps and bulk dislocations. We show here that steps can be observed in situ and in real time by means of a new method combining hygroscopy with phase contrast. First results raise interesting issues about the consequences of bicontinuous topology on the structure and dynamical behaviour of steps and dislocations

  5. Compound transstyloid, transscaphoid, perilunate fracture dislocation

    Directory of Open Access Journals (Sweden)

    Nadeem Ali

    2013-01-01

    Full Text Available Compound fracture dislocations of proximal carpal bones are very rare. We report a 26-year-old male, Defense personnel by profession, who sustained a compound Gustilo Anderson type IIIA transstyloid, transscaphoid, perilunate dislocation. The patient underwent primary proximal row carpectomy and stabilization with uni-planar, uni-lateral external fixator, and K-Wires. On follow-up after a year, the patient had almost negligible range of motion around wrist without any significant discomfort.

  6. Dislocation dynamics of web type silicon ribbon

    Energy Technology Data Exchange (ETDEWEB)

    Dillon, Jr, O W; Tsai, C T; DeAngelis, R J

    1987-03-01

    Silicon ribbon grown by the dendritic web process passes through a rapidly changing thermal profile in the growth direction. This rapidly changing profile induces stresses which produce changes in the dislocation density in the ribbon. A viscoplastic material response function (Haasen-Sumino model) is used herein to calculate the stresses and the dislocation density at each point in the silicon ribbon. The residual stresses are also calculated.

  7. Testing of a Single 11 T $Nb_3Sn$ Dipole Coil Using a Dipole Mirror Structure

    Energy Technology Data Exchange (ETDEWEB)

    Zlobin, Alexander [Fermilab; Andreev, Nicolai [Fermilab; Barzi, Emanuela [Fermilab; Chlachidze, Guram [Fermilab; Kashikhin, Vadim [Fermilab; Nobrega, Alfred [Fermilab; Novitski, Igor [Fermilab; Turrioni, Daniele [Fermilab; Karppinen, Mikko [CERN; Smekens, David [CERN

    2014-07-01

    FNAL and CERN are developing an 11 T Nb3Sn dipole suitable for installation in the LHC. To optimize coil design parameters and fabrication process and study coil performance, a series of 1 m long dipole coils is being fabricated. One of the short coils has been tested using a dipole mirror structure. This paper describes the dipole mirror magnetic and mechanical designs, and reports coil parameters and test results.

  8. Correlation of Etch Pits and Dislocations in As-grown and Thermal Cycle-Annealed HgCdTe(211) Films

    Science.gov (United States)

    Vaghayenegar, M.; Jacobs, R. N.; Benson, J. D.; Stoltz, A. J.; Almeida, L. A.; Smith, David J.

    2017-08-01

    This paper reports observations of the different types of etch pits and dislocations present in thick HgCdTe (211) layers grown by molecular beam epitaxy on CdTe/Si (211) composite substrates. Dislocation analysis for as-grown and thermal cycle-annealed samples has been carried out using bright-field transmission electron microscopy. Triangular pits present in as-grown material are associated with a mixture of Frank partials and perfect dislocations, while pits with fish-eye shapes have perfect dislocations with 1/2[0\\bar{1}1] Burgers vector. The dislocations beneath skew pits are more complex as they have two different crystallographic directions, and are associated with a mixture of Shockley partials and perfect dislocations. Dislocation analysis of samples after thermal cycle annealing (TCA) shows that the majority of dislocations under the etch pits are short segments of perfect dislocations with 1/2[0\\bar{1}1] Burgers vector while the remainder are Shockley partials. The absence of fish-eye shape pits in TCA samples suggests that they are associated with mobile dislocations that have reacted during annealing, causing the overall etch pit density to be reduced. Very large pits with a density ˜2×103 cm-2 are observed in as-grown and TCA samples. These defects thread from within the CdTe buffer layer into the upper regions of the HgCdTe layers. Their depth in as-grown material is so large that it is not possible to locate and identify the underlying defects.

  9. The epidemiology of shoulder dislocations in Oslo.

    Science.gov (United States)

    Liavaag, S; Svenningsen, S; Reikerås, O; Enger, M; Fjalestad, T; Pripp, A H; Brox, J I

    2011-12-01

    There are few previous studies on the incidence of shoulder dislocation in the general population. The aim of the study was to report the incidence of acute shoulder dislocations in the capital of Norway (Oslo) in 2009. Patients of all ages living in Oslo, sustaining a dislocation of the glenohumeral joint, were identified using electronic diagnosis registers, patient protocols, radiological registers of the hospitals, and the Norwegian Patient Register (NPR). The overall incidence rate was 56.3 [95% confidence interval (CI) 50.2-62.4] per 100,000 person-years, with rates of 82.2 (95% CI 71.7-92.8) and 30.9 (95% CI 24.5-37.3) in men and women, respectively. The incidence of primary dislocations was 26.2 (95% CI 22.1-30.4). The overall incidence of shoulder dislocations in Oslo was higher than previously reported incidences. The incidence of primary dislocations was also higher than that in previously reported studies for the general population but it was close to the incidence reported in Malmø, Sweden. © 2011 John Wiley & Sons A/S.

  10. Generalized dynamics of moving dislocations in quasicrystals

    International Nuclear Information System (INIS)

    Agiasofitou, Eleni; Lazar, Markus; Kirchner, Helmut

    2010-01-01

    A theoretical framework for dislocation dynamics in quasicrystals is provided according to the continuum theory of dislocations. Firstly, we present the fundamental theory for moving dislocations in quasicrystals giving the dislocation density tensors and introducing the dislocation current tensors for the phonon and phason fields, including the Bianchi identities. Next, we give the equations of motion for the incompatible elastodynamics as well as for the incompatible elasto-hydrodynamics of quasicrystals. We continue with the derivation of the balance law of pseudomomentum thereby obtaining the generalized forms of the Eshelby stress tensor, the pseudomomentum vector, the dynamical Peach-Koehler force density and the Cherepanov force density for quasicrystals. The form of the dynamical Peach-Koehler force for a straight dislocation is obtained as well. Moreover, we deduce the balance law of energy that gives rise to the generalized forms of the field intensity vector and the elastic power density of quasicrystals. The above balance laws are produced for both models. The differences between the two models and their consequences are revealed. The influences of the phason fields as well as of the dynamical terms are also discussed.

  11. Creep Deformation by Dislocation Movement in Waspaloy.

    Science.gov (United States)

    Whittaker, Mark; Harrison, Will; Deen, Christopher; Rae, Cathie; Williams, Steve

    2017-01-12

    Creep tests of the polycrystalline nickel alloy Waspaloy have been conducted at Swansea University, for varying stress conditions at 700 °C. Investigation through use of Transmission Electron Microscopy at Cambridge University has examined the dislocation networks formed under these conditions, with particular attention paid to comparing tests performed above and below the yield stress. This paper highlights how the dislocation structures vary throughout creep and proposes a dislocation mechanism theory for creep in Waspaloy. Activation energies are calculated through approaches developed in the use of the recently formulated Wilshire Equations, and are found to differ above and below the yield stress. Low activation energies are found to be related to dislocation interaction with γ' precipitates below the yield stress. However, significantly increased dislocation densities at stresses above yield cause an increase in the activation energy values as forest hardening becomes the primary mechanism controlling dislocation movement. It is proposed that the activation energy change is related to the stress increment provided by work hardening, as can be observed from Ti, Ni and steel results.

  12. Solitary excitations in discrete two-dimensional nonlinear Schrodinger models with dispersive dipole-dipole interactions

    DEFF Research Database (Denmark)

    Christiansen, Peter Leth; Gaididei, Yuri Borisovich; Johansson, M.

    1998-01-01

    The dynamics of discrete two-dimensional nonlinear Schrodinger models with long-range dispersive interactions is investigated. In particular, we focus on the cases where the dispersion arises from a dipole-dipole interaction, assuming the dipole moments at each lattice site to be aligned either...

  13. Permanent Electric Dipole-Dipole Interactions in Lyotropic Polypeptide Liquid Crystals

    OpenAIRE

    MORI, Norio; Norio, MORI; Research Associate, Department of Industrial Chemistry

    1981-01-01

    The interaction energy between two adjacent α-helical molecules was calculated taking into account for permanent electric dipoles locating orl the helical core of a polymer mainchain in order to explain the cholesteric structure of lyotropic polypeptide liquid crystals. It was concluded that the dipole-dipole interactions were responsible for the formation of the cholesteric structure.

  14. Representation of dislocation cores using Nye tensor distributions

    International Nuclear Information System (INIS)

    Hartley, Craig S.; Mishin, Y.

    2005-01-01

    This paper demonstrates how the cores of atomistically simulated dislocations in Cu and Al can be represented by a distribution of infinitesimal dislocations described by appropriate components of the Nye tensor. Components calculated from atomic positions in the dislocated crystal are displayed as contour plots on the plane normal to the dislocation line. The method provides an accurate and instructive means for characterizing dislocation core structures and calculating the total Burgers vector

  15. Reiterated inclusions of dipoles in a dense plasma

    International Nuclear Information System (INIS)

    Naouri, Gerard

    1983-01-01

    This thesis introduces a simple model made up for the calculation of pressure effects in dense and partially ionized 3 D two component plasma. The technic used is the description of the overlapping of atomic orbitals by means of interacting dipoles incased in one another. By iteration of this procedure we get an effective two-body potential which allows us to calculate line shifts of hydrogenic ions. In conclusion we suggest a possible improvement of the method by substituting a self consistent potential to the Debye one for the calculation of the wave functions. [fr

  16. Neutral dipole-dipole dimers: A new field in science

    Science.gov (United States)

    Kosower, Edward M.; Borz, Galina

    2018-03-01

    Dimer formation with dipole neutralization produces species such as low polarity water (LPW) compatible with hydrophobic surfaces (Phys. Chem. Chem. Phys. 2015, 17, 24895-24900) Dimerization and dipole neutralization occurs for N-methylacetamide on polyethylene, a behavior drastically different from its contortions in acetonitrile on AgBr:AgCl planar crystals (AgX) (ChemPhysChem 2014, 15, 3598-3607). The weak infrared absorption of the amide dimer on polyethylene is shown experimentally. Dimerization of palmitic acid is shown along with some of the many ramifications for intracellular systems. Polyoligomers of water are present on polyethylene surfaces. Some high resolution spectra of three of the polyoligomers of water are shown along with a mechanistic scheme for polyoligomer formation and dissolution. The structures of some of the oligomers are known from spectroscopic studies of water on AgX. The scope of the article begins with PE, generally accepted as hydrophobic. The IR of PE revealed not only that water was present but that it appeared in two forms, oligomers (O) and polyoligomers (PO). How did we recognize what they were? These species had been observed as especially strong "marker" peaks in the spectra1 of water placed on planar AgX, a platform developed by Katzir and his coworkers [6]. But there was a problem: the proximity to PE of oligomers with substantial (calculated) dipole moments and thus polarity, including cyclic hexamers of water (chair and boat forms), the cyclic pentamer, the books I and II, and the cyclic trimer [7a]. Another link was needed, a role perfectly fit by the already cited low polarity water (LPW). The choice was experimentally supported by the detection of low intensity absorption in the bending region.Some important generalities flow from these results. What other dimers might be present in the biological or chemical world? Palmitic acid dimer (PAD) would be a candidate for decreasing the polarity of the acid (PA). Another

  17. Activated states for cross-slip at screw dislocation intersections in face-centered cubic nickel and copper via atomistic simulation

    International Nuclear Information System (INIS)

    Rao, S.I.; Dimiduk, D.M.; El-Awady, J.A.; Parthasarathy, T.A.; Uchic, M.D.; Woodward, C.

    2010-01-01

    We extend our recent simulation studies where a screw dislocation in face-centered cubic (fcc) Ni was found to spontaneously attain a low energy partially cross-slipped configuration upon intersecting a forest dislocation. Using atomistic (molecular statics) simulations with embedded atom potentials, we evaluated the activation barrier for a dislocation to transform from fully residing on the glide plane to fully residing on a cross-slip plane intersecting a forest dislocation in both Ni and Cu. The activation energies were obtained by determining equilibrium configurations (energies) when variable pure tensile or compressive stresses were applied along the [1 1 1] direction on the partially cross-slipped state. We show that the activation energy is a factor of 2-5 lower than that for cross-slip in isolation via the Escaig process. The cross-slip activation energies obtained at the intersection in Cu were in reasonable accord with the experimentally determined cross-slip activation energy for Cu. Further, the activation barrier for cross-slip at these intersections was shown to be linearly proportional to (d/b)[ln(√(3)d/b)] 1/2 , as in the Escaig process, where d is the Shockley partial dislocation spacing and b is the Burgers vector of the screw dislocation. These results suggest that cross-slip should be preferentially observed at selected screw dislocation intersections in fcc materials.

  18. The core structure of a Frank dislocation in Ni3(Al,Nb)

    International Nuclear Information System (INIS)

    Bonnet, R.; Loubradou, M.; Derder, C.; Catana, A.

    1991-01-01

    This paper reports on the core structures of dislocations in L1 2 crystals, in view of understanding the anomalous yield behavior of strength with increasing temperature. Theoretical approaches have been proposed for explaining the dissociations of these dislocations, and experimental evidences have been reported for such dissociations using either the weak beam technique or more recently the HRTEM (High Resolution Transmission Electron Microscopy) technique. Recent HRTEM results show that for Ni 3 A1 the partial dislocations 1/2 left-angle 110 right-angle which limit an APB (Antiphase Boundary) lying on (001) are only split over 0.1 - 0.3 nm along (111) planes, producing very high energy CSF's (Complex Stacking Faults) which limit an SISF (superlattice Intrinsic Stacking Fault) extended on a (111) plane. Concerning the 1/2 left-angle 111 right-angle Frank dislocation, which limits an SESF (Superlattice Extrinsic Stacking Fault), there are no reported results yet. Let us note, however, that for aluminum HRTEM images of Frank dislocation loops have been studied. This lack of information in the L1 2 crystals motivated the present HRTEM study

  19. Intrathoracic fracture-dislocation of the humerus - case report and literature review

    Directory of Open Access Journals (Sweden)

    Wilson Carlos Sola Junior

    Full Text Available ABSTRACT Shoulder fracture-dislocations are uncommon. Those associated with intrathoracic dislocation are very rare conditions, resulting from high-energy trauma; usually, the affected limb is in an abduction position. In Brazil, there is only one report of a teenager with displacement of the epiphysis into the chest cavity; the present is the first adult patient report of intrathoracic dislocation of the humerus. The authors present the case of a patient female, aged 56 years, who was hit by motorcycle and thrown approximately 5 meters away. She was rescued on site with thoracic, pelvic, and right upper limb trauma. Her chest was drained due to pneumothorax and multiple fractures of ribs; she was diagnosed with fracture-dislocation in four parts, with intrathoracic dislocation of the humeral head. Displaced forearm bones fracture was also diagnosed; the olecranon, scaphoid, and ischiopubic fractures were not displaced. The patient underwent a joint procedure with a cardiothoracic surgery team to remove the humeral head through thoracotomy and chest drainage; subsequently, a partial arthroplasty of the humerus was performed, with graft from the humeral head and fixation of forearm fractures. Conservative treatment was chosen for the other fractures. After three months, all fractures were healed with gradual functional improvement. The patient remained in physiotherapy and orthopedic monitoring, having been discharged from the thoracic surgery; in a severe depressive episode, the patient committed suicide after 11 months of the trauma.

  20. Theoretical expectations for the muon's electric dipole moment

    International Nuclear Information System (INIS)

    Feng, Jonathan L.; Matchev, Konstantin T.; Shadmi, Yael

    2001-01-01

    We examine the muon's electric dipole moment d μ from a variety of theoretical perspectives. We point out that the reported deviation in the muon's g-2 can be due partially or even entirely to a new physics contribution to the muon's electric dipole moment. In fact, the recent g-2 measurement provides the most stringent bound on d μ to date. This ambiguity could be definitively resolved by the dedicated search for d μ recently proposed. We then consider both model-independent and supersymmetric frameworks. Under the assumptions of scalar degeneracy, proportionality, and flavor conservation, the theoretical expectations for d μ in supersymmetry fall just below the proposed sensitivity. However, nondegeneracy can give an order of magnitude enhancement, and lepton flavor violation can lead to d μ ∼10 -22 e cm, two orders of magnitude above the sensitivity of the d μ experiment. We present compact expressions for leptonic dipole moments and lepton flavor violating amplitudes. We also derive new limits on the amount of flavor violation allowed and demonstrate that approximations previously used to obtain such limits are highly inaccurate in much of parameter space

  1. Iron saturation control in RHIC dipole magnets

    International Nuclear Information System (INIS)

    Thompson, P.A.; Gupta, R.C.; Kahn, S.A.; Hahn, H.; Morgan, G.H.; Wanderer, P.J.; Willen, E.

    1991-01-01

    The Relativistic Heavy Ion Collider (RHIC) will require 360 dipoles of 80 mm bore. This paper discusses the field perturbations produced by the saturation of the yoke iron. Changes have been made to the yoke to reduce these perturbations, in particular, decapole -4 . Measurements and calculations for 6 series of dipole magnets are presented. 2 refs., 2 figs., 1 tab

  2. Microscopic evaluation of the nuclear dipole polarizability

    Energy Technology Data Exchange (ETDEWEB)

    Lipparini, E; Orlandini, G; Stringari, S; Traini, M [Trento Univ. (Italy). Dept. di Matematica e Fisica

    1977-12-01

    The dipole polarizability sum rule has been evaluated by means of a restricted Hartree-Fock approach. The method leads to a simple and analytical expression for the dipole polarizability. Explicit calculations have been performed in /sup 16/O and /sup 40/Ca with different types of interaction.

  3. Electric dipoles on the Bloch sphere

    OpenAIRE

    Vutha, Amar C.

    2014-01-01

    The time evolution of a two-level quantum mechanical system can be geometrically described using the Bloch sphere. By mapping the Bloch sphere evolution onto the dynamics of oscillating electric dipoles, we provide a physically intuitive link between classical electromagnetism and the electric dipole transitions of atomic & molecular physics.

  4. Giant dipole resonance by many levels theory

    International Nuclear Information System (INIS)

    Mondaini, R.P.

    1977-01-01

    The many levels theory is applied to photonuclear effect, in particular, in giant dipole resonance. A review about photonuclear dipole absorption, comparing with atomic case is done. The derivation of sum rules; their modifications by introduction of the concepts of effective charges and mass and the Siegert theorem. The experimental distributions are compared with results obtained by curve adjustment. (M.C.K.) [pt

  5. Electric dipoles on the Bloch sphere

    International Nuclear Information System (INIS)

    Vutha, Amar C

    2015-01-01

    The time evolution of a two-level quantum mechanical system can be geometrically described using the Bloch sphere. By mapping the Bloch sphere evolution onto the dynamics of oscillating electric dipoles, we provide a physically intuitive link between classical electromagnetism and the electric dipole transitions of atomic and molecular physics. (paper)

  6. Droplet-model electric dipole moments

    International Nuclear Information System (INIS)

    Myers, W.D.; Swiatecki, W.J.

    1991-01-01

    Denisov's recent criticism of the droplet-model formula for the dipole moment of a deformed nucleus as derived by Dorso et al., it shown to be invalid. This helps to clarify the relation of theory to the measured dipole moments, as discussed in the review article by Aberg et al. (orig.)

  7. Electrostatic-Dipole (ED) Fusion Confinement Studies

    Science.gov (United States)

    Miley, George H.; Shrestha, Prajakti J.; Yang, Yang; Thomas, Robert

    2004-11-01

    The Electrostatic-Dipole (ED) concept significantly differs from a "pure" dipole confinement device [1] in that the charged particles are preferentially confined to the high-pressure region interior of the dipole coil by the assistance of a surrounding spherical electrostatic grid. In present ED experiments, a current carrying coil is embedded inside the grid of an IEC such as to produce a magnetic dipole field. Charged particles are injected axisymmetrically from an ion gun (or duo-plasmatron) into the center of the ED confinement grid/dipole ring where they oscillate along the magnetic field lines and pass the peak field region at the center of the dipole region. As particles begin accelerating away from the center region towards the outer electrostatic grid region, they encounter a strong electrostatic potential (order of 10's of kilovolts) retarding force. The particles then decelerate, reverse direction and re-enter the dipole field region where again magnetic confinement dominates. This process continues, emulating a complex harmonic oscillator motion. The resulting pressure profile averaged over the field curvature offers good plasma stability in the ED configuration. The basic concept and results from preliminary experiments will be described. [1] M.E. Mauel, et al. "Dipole Equilibrium and Stability," 18th IAEA Conference of Plasma Phys. and Control. Nuclear Fusion, Varenna, Italy 2000, IAEA-F1-CN-70/TH

  8. Slice of LHC dipole wiring

    CERN Multimedia

    Dipole model slice made in 1994 by Ansaldo. The high magnetic fields needed for guiding particles around the Large Hadron Collider (LHC) ring are created by passing 12’500 amps of current through coils of superconducting wiring. At very low temperatures, superconductors have no electrical resistance and therefore no power loss. The LHC is the largest superconducting installation ever built. The magnetic field must also be extremely uniform. This means the current flowing in the coils has to be very precisely controlled. Indeed, nowhere before has such precision been achieved at such high currents. 50’000 tonnes of steel sheets are used to make the magnet yokes that keep the wiring firmly in place. The yokes constitute approximately 80% of the accelerator's weight and, placed side by side, stretch over 20 km!

  9. Top down electroweak dipole operators

    Science.gov (United States)

    Fuyuto, Kaori; Ramsey-Musolf, Michael

    2018-06-01

    We derive present constraints on, and prospective sensitivity to, the electric dipole moment (EDM) of the top quark (dt) implied by searches for the EDMs of the electron and nucleons. Above the electroweak scale v, the dt arises from two gauge invariant operators generated at a scale Λ ≫ v that also mix with the light fermion EDMs under renormalization group evolution at two-loop order. Bounds on the EDMs of first generation fermion systems thus imply bounds on |dt |. Working in the leading log-squared approximation, we find that the present upper bound on |dt | is 10-19 e cm for Λ = 1 TeV, except in regions of finely tuned cancellations that allow for |dt | to be up to fifty times larger. Future de and dn probes may yield an order of magnitude increase in dt sensitivity, while inclusion of a prospective proton EDM search may lead to an additional increase in reach.

  10. Dislocation Dynamics in Al-Li Alloys. Mean Jump Distance and Activation Length of Moving Dislocations

    NARCIS (Netherlands)

    Hosson, J.Th.M. De; Huis in 't Veld, A.; Tamler, H.; Kanert, O.

    1984-01-01

    Pulsed nuclear magnetic resonance proved to be a complementary new technique for the study of moving dislocations in Al-Li alloys. The NMR technique, in combination with transmission electron microscopy and strain-rate change experiments have been applied to study dislocation motion in Al-2.2 wt% Li

  11. High-field dipoles for future accelerators

    International Nuclear Information System (INIS)

    Wipf, S.L.

    1984-09-01

    This report presents the concept for building superconducting accelerator dipoles with record high fields. Economic considerations favor the highest possible current density in the windings. Further discussion indicates that there is an optimal range of pinning strength for a superconducting material and that it is not likely for multifilamentary conductors to ever equal the potential performance of tape conductors. A dipole design with a tape-wound, inner high-field winding is suggested. Methods are detailed to avoid degradation caused by flux jumps and to overcome problems with the dipole ends. Concerns for force support structure and field precision are also addressed. An R and D program leading to a prototype 11-T dipole is outlined. Past and future importance of superconductivity to high-energy physics is evident from a short historical survey. Successful dipoles in the 10- to 20-T range will allow interesting options for upgrading present largest accelerators

  12. The dipole response of {sup 132}Sn

    Energy Technology Data Exchange (ETDEWEB)

    Schrock, Philipp; Aumann, Thomas; Johansen, Jacob; Schindler, Fabia [IKP, TU Darmstadt (Germany); Boretzky, Konstanze [GSI Helmholtzzentrum (Germany); Rossi, Dominic [Michigan State University (United States); Collaboration: R3B-Collaboration

    2015-07-01

    The Isovector Giant Dipole Resonance (IVGDR) is a well-known collective excitation in which all protons oscillate against all neutrons of a nucleus. In neutron-rich nuclei an additional low-lying dipole excitation occurs, often denoted as Pygmy Dipole Resonance (PDR). To study the PDR in exotic Sn-isotopes, an experiment has been successfully performed with the upgraded R{sup 3}B-LAND setup at GSI. The complete-kinematics measurement of all reaction participants allows for the reconstuction of the excitation energy and, hence, the extraction of the dipole strength. Presented are the main features of the experiment, the analysis concept and the current status of the analysis of the dipole response of the doubly-magic isotope {sup 132}Sn.

  13. Elastic fields, dipole tensors, and interaction between self-interstitial atom defects in bcc transition metals

    Science.gov (United States)

    Dudarev, S. L.; Ma, Pui-Wai

    2018-03-01

    Density functional theory (DFT) calculations show that self-interstitial atom (SIA) defects in nonmagnetic body-centered-cubic (bcc) metals adopt strongly anisotropic configurations, elongated in the direction [S. Han et al., Phys. Rev. B 66, 220101 (2002), 10.1103/PhysRevB.66.220101; D. Nguyen-Manh et al., Phys. Rev. B 73, 020101 (2006), 10.1103/PhysRevB.73.020101; P. M. Derlet et al., Phys. Rev. B 76, 054107 (2007), 10.1103/PhysRevB.76.054107; S. L. Dudarev, Annu. Rev. Mater. Res. 43, 35 (2013), 10.1146/annurev-matsci-071312-121626]. Elastic distortions, associated with such anisotropic atomic structures, appear similar to distortions around small prismatic dislocation loops, although the extent of this similarity has never been quantified. We derive analytical formulas for the dipole tensors of SIA defects, which show that, in addition to the prismatic dislocation looplike character, the elastic field of a SIA defect also has a significant isotropic dilatation component. Using empirical potentials and DFT calculations, we parametrize dipole tensors of defects for all the nonmagnetic bcc transition metals. This enables a quantitative evaluation of the energy of elastic interaction between the defects, which also shows that in a periodic three-dimensional simple cubic arrangement of crowdions, long-range elastic interactions between a defect and all its images favor a orientation of the defect.

  14. Molecular dynamics simulation of dislocation intersections in aluminum

    International Nuclear Information System (INIS)

    Li, M.; Chu, W.Y.; Qian, C.F.; Gao, K.W.; Qiao, L.J.

    2003-01-01

    The molecular dynamics method is used to simulate dislocation intersection in aluminum containing 1.6x10 6 atoms using embedded atom method (EAM) potential. The results show that after intersection between two right-hand screw dislocations of opposite sign there are an extended jog corresponding to a row of 1/3 vacancies in the intersected dislocation, and a trail of vacancies behind the moving dislocation. After intersection between screw dislocations of same sign, there are an extended jog corresponding to a row of 1/3 interstitials in the intersected dislocation, and a trail of interstitials behind the moving dislocation. After intersection between screw and edge dislocations with different Burgers vector, there are a constriction corresponding to one 1/3 vacancy in the edge dislocation, and no point-defects behind the screw dislocation. When a moving screw dislocation intersects an edge dislocation with the same Burgers vector, the point of intersection will split into two constrictions corresponding to one 1/3 vacancy and 1/3 interstitial, respectively. The moving screw dislocation can pass the edge dislocation only after the two constrictions, which can move along the line of intersection of the two slip planes, meet and annihilate

  15. Topological Nematic States and Non-Abelian Lattice Dislocations

    Directory of Open Access Journals (Sweden)

    Maissam Barkeshli

    2012-08-01

    Full Text Available An exciting new prospect in condensed matter physics is the possibility of realizing fractional quantum Hall states in simple lattice models without a large external magnetic field. A fundamental question is whether qualitatively new states can be realized on the lattice as compared with ordinary fractional quantum Hall states. Here we propose new symmetry-enriched topological states, topological nematic states, which are a dramatic consequence of the interplay between the lattice translational symmetry and topological properties of these fractional Chern insulators. The topological nematic states are realized in a partially filled flat band with a Chern number N, which can be mapped to an N-layer quantum Hall system on a regular lattice. However, in the topological nematic states the lattice dislocations can act as wormholes connecting the different layers and effectively change the topology of the space. Consequently, lattice dislocations become defects with a nontrivial quantum dimension, even when the fractional quantum Hall state being realized is, by itself, Abelian. Our proposal leads to the possibility of realizing the physics of topologically ordered states on high-genus surfaces in the lab even though the sample has only the disk geometry.

  16. Topological Nematic States and Non-Abelian Lattice Dislocations

    Science.gov (United States)

    Barkeshli, Maissam; Qi, Xiao-Liang

    2012-07-01

    An exciting new prospect in condensed matter physics is the possibility of realizing fractional quantum Hall states in simple lattice models without a large external magnetic field. A fundamental question is whether qualitatively new states can be realized on the lattice as compared with ordinary fractional quantum Hall states. Here we propose new symmetry-enriched topological states, topological nematic states, which are a dramatic consequence of the interplay between the lattice translational symmetry and topological properties of these fractional Chern insulators. The topological nematic states are realized in a partially filled flat band with a Chern number N, which can be mapped to an N-layer quantum Hall system on a regular lattice. However, in the topological nematic states the lattice dislocations can act as wormholes connecting the different layers and effectively change the topology of the space. Consequently, lattice dislocations become defects with a nontrivial quantum dimension, even when the fractional quantum Hall state being realized is, by itself, Abelian. Our proposal leads to the possibility of realizing the physics of topologically ordered states on high-genus surfaces in the lab even though the sample has only the disk geometry.

  17. High dislocation density of tin induced by electric current

    International Nuclear Information System (INIS)

    Liao, Yi-Han; Liang, Chien-Lung; Lin, Kwang-Lung; Wu, Albert T.

    2015-01-01

    A dislocation density of as high as 10 17 /m 2 in a tin strip, as revealed by high resolution transmission electron microscope, was induced by current stressing at 6.5 x 10 3 A/ cm 2 . The dislocations exist in terms of dislocation line, dislocation loop, and dislocation aggregates. Electron Backscattered Diffraction images reflect that the high dislocation density induced the formation of low deflection angle subgrains, high deflection angle Widmanstätten grains, and recrystallization. The recrystallization gave rise to grain refining

  18. Void growth suppression by dislocation impurity atmospheres

    International Nuclear Information System (INIS)

    Weertman, J.; Green, W.V.

    1976-01-01

    A detailed calculation is given of the effect of an impurity atmosphere on void growth under irradiation damage conditions. Norris has proposed that such an atmosphere can suppress void growth. The hydrostatic stress field of a dislocation that is surrounded by an impurity atmosphere was found and used to calculate the change in the effective radius of a dislocation line as a sink for interstitials and vacancies. The calculation of the impurity concentration in a Cottrell cloud takes into account the change in hydrostatic pressure produced by the presence of the cloud itself. It is found that void growth is eliminated whenever dislocations are surrounded by a condensed atmosphere of either oversized substitutional impurity atoms or interstitial impurity atoms. A condensed atmosphere will form whenever the average impurity concentration is larger than a critical concentration

  19. Femoral head fracture without hip dislocation

    Directory of Open Access Journals (Sweden)

    Aggarwal Aditya K

    2013-10-01

    Full Text Available 【Abstract】Femoral head fractures without dislocation or subluxation are extremely rare injuries. We report a neglected case of isolated comminuted fracture of femoral head without hip dislocation or subluxation of one year duration in a 36-year-old patient who sustained a high en- ergy trauma due to road traffic accident. He presented with painful right hip and inability to bear full weight on right lower limb with Harris hip score of 39. He received cementless total hip replacement. At latest follow-up of 2.3 years, functional outcome was excellent with Harris hip score of 95. Such isolated injuries have been described only once in the literature and have not been classified till now. The purpose of this report is to highlight the extreme rarity, possible mechanism involved and a novel classification system to classify such injuries. Key words: Femur head; Hip dislocation; Classification; Arthroplasty, replacement, hip

  20. Rare Inferior Shoulder Dislocation (Luxatio Erecta

    Directory of Open Access Journals (Sweden)

    Hakan Cift

    2015-01-01

    Full Text Available Although shoulder dislocations have been seen very frequently, inferior dislocation of shoulder constitutes only 0.5% of all shoulder dislocations. We share our 4 patients with luxatio erecta and present their last clinical control. 2 male and 2 female Caucasian patients were diagnosed as luxatio erecta. Patients’ ages were 78, 62, 65, and 76. All patients’ reduction was done by traction-abduction and contour traction maneuver in the operating room. The patients had no symptoms and no limitation of range of motion of their shoulder at their last control. Luxatio erecta is seen rarely, and these patients may have neurovascular injury. These patients should be carefully examined and treated by the orthopaedic and traumatology surgeons.

  1. Rare Inferior Shoulder Dislocation (Luxatio Erecta)

    Science.gov (United States)

    Cift, Hakan; Soylemez, Salih; Demiroglu, Murat; Ozkan, Korhan; Ozden, Vahit Emre; Ozkut, Afsar T.

    2015-01-01

    Although shoulder dislocations have been seen very frequently, inferior dislocation of shoulder constitutes only 0.5% of all shoulder dislocations. We share our 4 patients with luxatio erecta and present their last clinical control. 2 male and 2 female Caucasian patients were diagnosed as luxatio erecta. Patients' ages were 78, 62, 65, and 76. All patients' reduction was done by traction-abduction and contour traction maneuver in the operating room. The patients had no symptoms and no limitation of range of motion of their shoulder at their last control. Luxatio erecta is seen rarely, and these patients may have neurovascular injury. These patients should be carefully examined and treated by the orthopaedic and traumatology surgeons. PMID:25883820

  2. Constraints on exotic dipole-dipole couplings between electrons at the micron scale

    Science.gov (United States)

    Kotler, Shlomi; Ozeri, Roee; Jackson Kimball, Derek

    2015-05-01

    Until recently, the magnetic dipole-dipole coupling between electrons had not been directly observed experimentally. This is because at the atomic scale dipole-dipole coupling is dominated by the exchange interaction and at larger distances the dipole-dipole coupling is overwhelmed by ambient magnetic field noise. In spite of these challenges, the magnetic dipole-dipole interaction between two electron spins separated by 2.4 microns was recently measured using the valence electrons of trapped Strontium ions [S. Kotler, N. Akerman, N. Navon, Y. Glickman, and R. Ozeri, Nature 510, 376 (2014)]. We have used this measurement to directly constrain exotic dipole-dipole interactions between electrons at the micron scale. For light bosons (mass 0.1 eV), we find that coupling constants describing pseudoscalar and axial-vector mediated interactions must be | gPegPe/4 πℏc | <= 1 . 5 × 10-3 and | gAegAe/4 πℏc | <= 1 . 2 × 10-17 , respectively, at the 90% confidence level. These bounds significantly improve on previous constraints in this mass range: for example, the constraints on axial-vector interactions are six orders of magnitude stronger than electron-positron constraints based on positronium spectroscopy. Supported by the National Science Foundation, I-Core: the Israeli excellence center, and the European Research Council.

  3. Parquet: Regions of areal plastic dislocations (on Venus)

    Science.gov (United States)

    Sukhanov, A. L.

    1986-01-01

    The extensive flat elevations of the Northern Hemisphere of Venus are covered with frequently intersecting lines of dislocations, resembling the outline of a giant parquet. In the internal sections of these regions we find grabens and regions of extension, and on the periphery lobe-shaped flow structures. The parquet was formed after the beginning of the formation of the lava plains, but covered by the youngest lava. These structures apparently arose partly because of the dragging of blocks of crust by the asthenospheric flows, and partly in the gravitational sliding of such heated blocks in the partial melting of their base. It is possible that these elevations occupy on Venus the place of the Earth's rift systems.

  4. Configuration and local elastic interaction of ferroelectric domains and misfit dislocation in PbTiO3/SrTiO3 epitaxial thin films

    Directory of Open Access Journals (Sweden)

    Takanori Kiguchi, Kenta Aoyagi, Yoshitaka Ehara, Hiroshi Funakubo, Tomoaki Yamada, Noritaka Usami and Toyohiko J Konno

    2011-01-01

    Full Text Available We have studied the strain field around the 90° domains and misfit dislocations in PbTiO3/SrTiO3 (001 epitaxial thin films, at the nanoscale, using the geometric phase analysis (GPA combined with high-resolution transmission electron microscopy (HRTEM and high-angle annular dark field––scanning transmission electron microscopy (HAADF-STEM. The films typically contain a combination of a/c-mixed domains and misfit dislocations. The PbTiO3 layer was composed from the two types of the a-domain (90° domain: a typical a/c-mixed domain configuration where a-domains are 20–30 nm wide and nano sized domains with a width of about 3 nm. In the latter case, the nano sized a-domain does not contact the film/substrate interface; it remains far from the interface and stems from the misfit dislocation. Strain maps obtained from the GPA of HRTEM images show the elastic interaction between the a-domain and the dislocations. The normal strain field and lattice rotation match each other between them. Strain maps reveal that the a-domain nucleation takes place at the misfit dislocation. The lattice rotation around the misfit dislocation triggers the nucleation of the a-domain; the normal strains around the misfit dislocation relax the residual strain in a-domain; then, the a-domain growth takes place, accompanying the introduction of the additional dislocation perpendicular to the misfit dislocation and the dissociation of the dislocations into two pairs of partial dislocations with an APB, which is the bottom boundary of the a-domain. The novel mechanism of the nucleation and growth of 90° domain in PbTiO3/SrTiO3 epitaxial system has been proposed based on above the results.

  5. High-temperature discrete dislocation plasticity

    Science.gov (United States)

    Keralavarma, S. M.; Benzerga, A. A.

    2015-09-01

    A framework for solving problems of dislocation-mediated plasticity coupled with point-defect diffusion is presented. The dislocations are modeled as line singularities embedded in a linear elastic medium while the point defects are represented by a concentration field as in continuum diffusion theory. Plastic flow arises due to the collective motion of a large number of dislocations. Both conservative (glide) and nonconservative (diffusion-mediated climb) motions are accounted for. Time scale separation is contingent upon the existence of quasi-equilibrium dislocation configurations. A variational principle is used to derive the coupled governing equations for point-defect diffusion and dislocation climb. Superposition is used to obtain the mechanical fields in terms of the infinite-medium discrete dislocation fields and an image field that enforces the boundary conditions while the point-defect concentration is obtained by solving the stress-dependent diffusion equations on the same finite-element grid. Core-level boundary conditions for the concentration field are avoided by invoking an approximate, yet robust kinetic law. Aspects of the formulation are general but its implementation in a simple plane strain model enables the modeling of high-temperature phenomena such as creep, recovery and relaxation in crystalline materials. With emphasis laid on lattice vacancies, the creep response of planar single crystals in simple tension emerges as a natural outcome in the simulations. A large number of boundary-value problem solutions are obtained which depict transitions from diffusional to power-law creep, in keeping with long-standing phenomenological theories of creep. In addition, some unique experimental aspects of creep in small scale specimens are also reproduced in the simulations.

  6. Measurements of passive correction of magnetization higher multipoles in one meter long dipoles

    International Nuclear Information System (INIS)

    Green, M.A.; Althaus, R.F.; Barale, P.J.; Benjegerdes, R.W.; Gilbert, W.S.; Green, M.I.; Scanlan, R.M.; Taylor, C.E.

    1990-09-01

    The use of passive superconductor to correct the magnetization sextupole and decapole in SSC dipoles appears to be promising. This paper presents the results of a series of experiments of passive superconductor correctors in one meter long dipole magnets. Reduction of the magnetization sextupole by a factor of five to ten has been achieved using the passive superconductor correctors. The magnetization decapole was also reduced. The passive superconductor correctors reduced the sextupole temperature sensitivity by an order of magnitude. Flux creep decay was partially compensated for by the correctors. 13 refs., 7 figs

  7. Effects of stacking fault energies on the interaction between an edge dislocation and an 8.0-nm-diameter Frank loop of self-interstitial atoms

    Directory of Open Access Journals (Sweden)

    S. Hayakawa

    2016-12-01

    Full Text Available Molecular dynamics simulations were conducted to investigate the effects of stacking fault energy (SFE as a single variable parameter on the interaction between an edge dislocation and a Frank loop of self-interstitial atoms with a diameter of 8.0nm. The physical contact between the edge dislocation and the loop causes constriction of the edge dislocation, followed by the formation of a D-Shockley partial dislocation. The latter process is associated with either the formation of a screw component and its cross-slip, or the direct core reaction between the dislocation and the loop. These processes induce either the absorption of the loop into the dislocation or the transformation of the loop into a perfect loop. The SFE influences the interaction morphologies by determining the separation distance of the two partial dislocations and consequently the rate of constriction. The dependence of the interaction morphology on the SFE varies with the habit plane of the loop. A higher SFE increases the probability of the absorption or transformation interaction; however, only loop shearing is observed at the lower limit of the SFE range of austenitic stainless steels.

  8. SSC collider dipole magnet end mechanical design

    International Nuclear Information System (INIS)

    Delchamps, S.W.; Bossert, R.C.; Carson, J.; Ewald, K.; Fulton, H.; Kerby, J.; Koska, W.; Strait, J.; Wake, S.M.; Leung, K.K.

    1991-05-01

    This paper describes the mechanical design of the ends of Superconducting Super Collider dipole magnets to be constructed and tested at Fermilab. Coil end clamps, end yoke configuration, and end plate design are discussed. Loading of the end plate by axial Lorentz forces is discussed. Relevant data from 40 mm and 50 mm aperture model dipole magnets built and tested at Fermilab are presented. In particular, the apparent influence of end clamp design on the quench behavior of model SSC dipoles is described. 8 refs., 3 figs

  9. Plasma confinement in a magnetic dipole

    International Nuclear Information System (INIS)

    Kesner, J.; Bromberg, L.; Garnier, D.; Mauel, M.

    1999-01-01

    A dipole fusion confinement device is stable to MHD interchange and ballooning modes when the pressure profile is sufficiently gentle. The plasma can be confined at high beta, is steady state and disruption free. Theory indicates that when the pressure gradient is sufficiently gentle to satisfy MHD requirements drift waves will also be stable. The dipole approach is particularly applicable for advanced fuels. A new experimental facility is presently being built to test the stability and transport properties of a dipole-confined plasma. (author)

  10. Plasma confinement in a magnetic dipole

    International Nuclear Information System (INIS)

    Kesner, J.; Bromberg, L.; Garnier, D.; Mauel, M.

    2001-01-01

    A dipole fusion confinement device is stable to MHD interchange and ballooning modes when the pressure profile is sufficiently gentle. The plasma can be confined at high beta, is steady state and disruption free. Theory indicates that when the pressure gradient is sufficiently gentle to satisfy MHD requirements drift waves will also be stable. The dipole approach is particularly applicable for advanced fuels. A new experimental facility is presently being built to test the stability and transport properties of a dipole-confined plasma. (author)

  11. Is the 2MASS dipole convergent?

    OpenAIRE

    Chodorowski, Michał; Bilicki, Maciej; Mamon, Gary A.; Jarrett, Thomas

    2010-01-01

    We study the growth of the clustering dipole of galaxies from the Two Micron All Sky Survey (2MASS). We find that the dipole does not converge before the completeness limit of the 2MASS Extended Source Catalog, i.e. up to about 300 Mpc/h. We compare the observed growth of the dipole with the theoretically expected, conditional growth for the LambdaCDM power spectrum and cosmological parameters constrained by WMAP. The observed growth turns out to be within 1-sigma confidence level of the theo...

  12. Dipole moments of the rho meson

    International Nuclear Information System (INIS)

    Hecht, M.B.; McKellar, B.H.P.

    1997-04-01

    The electric and magnetic dipole moments (EDM) of the rho meson are calculated using the propagators and vertices derived from the quantum chromodynamics Dyson-Schwinger equations. Results obtained from using the Bethe-Salpeter amplitude studied by Chappell, Mitchell et. al., and Pichowsky and Lee, are compared. The rho meson EDM is generated through the inclusion of a quark electric dipole moment, which is left as a free variable. These results are compared to the perturbative results to obtain a measure of the effects of quark interactions and confinement. The two dipole moments are also calculated using the phenomenological MIT bag model to provide a further basis for comparison

  13. Basal-plane dislocations in bilayer graphene - Peculiarities in a quasi-2D material

    Science.gov (United States)

    Butz, Benjamin

    2015-03-01

    Dislocations represent one of the most fascinating and fundamental concepts in materials science. First and foremost, they are the main carriers of plastic deformation in crystalline materials. Furthermore, they can strongly alter the local electronic or optical properties of semiconductors and ionic crystals. In layered crystals like graphite dislocation movement is restricted to the basal plane. Thus, those basal-plane dislocations cannot escape enabling their confinement in between only two atomic layers of the material. So-called bilayer graphene is the thinnest imaginable quasi-2D crystal to explore the nature and behavior of dislocations under such extreme boundary conditions. Robust graphene membranes derived from epitaxial graphene on SiC provide an ideal platform for their investigation. The presentation will give an insight in the direct observation of basal-plane partial dislocations by transmission electron microscopy and their detailed investigation by diffraction contrast analysis and atomistic simulations. The investigation reveals striking size effects. First, the absence of stacking fault energy, a unique property of bilayer graphene, leads to a characteristic dislocation pattern, which corresponds to an alternating AB BA change of the stacking order. Most importantly, our experiments in combination with atomistic simulations reveal a pronounced buckling of the bilayer graphene membrane, which directly results from accommodation of strain. In fact, the buckling completely changes the strain state of the bilayer graphene and is of key importance for its electronic/spin transport properties. Due to the high degree of disorder in our quasi-2D material it is one of the very few examples for a perfect linear magnetoresistance, i.e. the linear dependency of the in-plane electrical resistance on a magnetic field applied perpendicular to the graphene sheet up to field strengths of more than 60 T. This research is financed by the German Research Foundation

  14. MR imaging of subscapularis tendon injury in the setting of anterior shoulder dislocation

    Energy Technology Data Exchange (ETDEWEB)

    Gyftopoulos, Soterios; Carpenter, Elizabeth; Kazam, Jonathan; Babb, James; Bencardino, Jenny [NYU Hospital for Joint Diseases, New York, NY (United States)

    2012-11-15

    To evaluate the degree and location patterns of subscapularis tendon injury in patients with prior anterior shoulder dislocation (ASD). Forty-five consecutive MR shoulder examinations in patients with a history of ASD and 20 consecutive MR examinations in patients without prior dislocation were reviewed. Two readers assessed for the presence and location of tendinosis and tearing in the subscapularis tendon, which was divided into three segments: superior, middle, and inferior. The readers also documented the presence of anterior labral tears, osseous Bankart defects and Hill-Sachs lesions. Fisher's exact tests were performed to analyze the different types of pathology and their locations. Subscapularis tendinosis, and partial thickness and full thickness tears were more common in patients with a history of ASD. Tendinosis was found in 60-64.4% of the dislocation patients compared with 40% of the non-dislocation group. When stratified by location, the middle and inferior thirds were the most commonly affected with statistical significance (p < 0.05) found in tearing of the inferior third. Anterior labral tears, osseous Bankart defects, and Hill-Sachs lesions were more common in the dislocation group with statistically significant associations with tendinosis in the middle and inferior thirds and tearing of the middle third (p < 0.05). Our study suggests an association between middle and inferior subscapularis tendon pathology and prior anterior shoulder dislocation. Based on our results, careful MR assessment of the subscapularis tendon by the radiologist is indicated in the setting of ASD as injury of this structure can be symptomatic and may be amenable to treatment. (orig.)

  15. MR imaging of subscapularis tendon injury in the setting of anterior shoulder dislocation

    International Nuclear Information System (INIS)

    Gyftopoulos, Soterios; Carpenter, Elizabeth; Kazam, Jonathan; Babb, James; Bencardino, Jenny

    2012-01-01

    To evaluate the degree and location patterns of subscapularis tendon injury in patients with prior anterior shoulder dislocation (ASD). Forty-five consecutive MR shoulder examinations in patients with a history of ASD and 20 consecutive MR examinations in patients without prior dislocation were reviewed. Two readers assessed for the presence and location of tendinosis and tearing in the subscapularis tendon, which was divided into three segments: superior, middle, and inferior. The readers also documented the presence of anterior labral tears, osseous Bankart defects and Hill-Sachs lesions. Fisher's exact tests were performed to analyze the different types of pathology and their locations. Subscapularis tendinosis, and partial thickness and full thickness tears were more common in patients with a history of ASD. Tendinosis was found in 60-64.4% of the dislocation patients compared with 40% of the non-dislocation group. When stratified by location, the middle and inferior thirds were the most commonly affected with statistical significance (p < 0.05) found in tearing of the inferior third. Anterior labral tears, osseous Bankart defects, and Hill-Sachs lesions were more common in the dislocation group with statistically significant associations with tendinosis in the middle and inferior thirds and tearing of the middle third (p < 0.05). Our study suggests an association between middle and inferior subscapularis tendon pathology and prior anterior shoulder dislocation. Based on our results, careful MR assessment of the subscapularis tendon by the radiologist is indicated in the setting of ASD as injury of this structure can be symptomatic and may be amenable to treatment. (orig.)

  16. The neutron electric dipole moment

    International Nuclear Information System (INIS)

    He, X.G.; McKellar, B.H.J.; Pakvasa, S.

    1989-01-01

    A systematic study was made of the electric dipole moment (EDM) of neutron D n in various models of CP violation. It was found that in the standard KM model with 3 families the neutron EDM is in the range 1.4x10 -33 ≤ D n ≤ 1.6x10 -31 ecm; that the two Higgs doublet model has approximately the same value of D n as the standard model; that D n in the Weinberg model is predicted to satisfy D n > 10 -25 ecm; that in a class of left-right symmetric models D n is of the order of 10 -26-11 ecm; that in supersymmetric models D n is of the order 10 -22 φ ecm with φ being the possible phase difference of the phases of gluino mass and the gluino-quark-smark mixing matrix and that the strong CP parameter θ is found to be θ -9 , using the present experimental limit that D n -25 ecm with 90% confidence. 65 refs., 10 figs

  17. Superconducting Coil of Po Dipole

    CERN Multimedia

    1983-01-01

    The Po superconducting dipole was built as a prototype beam transport magnet for the SPS extracted proton beam P0. Its main features were: coil aperture 72 mm, length 5 m, room-temperature yoke, NbTi cable conductor impregnated with solder, nominal field 4.2 T at 4.7 K (87% of critical field). It reached its nominal field without any quench.After this successful test up to its nominal field of 4.2 T, the power was not raised to reach a quench. The magnet was not installed in a beam and had no other further use. Nevertheless its construction provided knowledges and experience which became useful in the design and construction of the LHC magnets. The photo shows a detail of the inner layer winding before superposing the outer layer to form the complete coil of a pole. Worth noticing is the interleaved glass-epoxy sheet (white) with grooved channels for the flow of cooling helium. See also 8211532X.

  18. Dislocation-cavity interaction in Fe: a comparison between molecular dynamics and dislocation dynamics

    International Nuclear Information System (INIS)

    Hafez Haghighat, S.M.; Schaeublin, R.; Fivel, M.C.

    2007-01-01

    Full text of publication follows: multi-scale modeling, including molecular dynamics (MD) and discrete dislocation dynamics (DDD) methods, appears as a significant tool for the description of plasticity and mechanical properties of materials. This research is on the investigation of the subsequence effects of irradiation on the plasticity of pure Fe and focuses on the interaction of a single dislocation and a spherical cavity, as void or He bubble. Extensive MD simulations of the interaction under imposed strain rate [1, 2] have shown that various temperatures and cavity sizes result in different release stresses depending on dislocation bow out. It appears that a temperature increase and cavity size decrease reduce the cavity strength. MD simulation shows that the elastic field around the cavity is largely anisotropic. This anisotropy may influence the way the dislocation unpins from the cavity. Following the MD simulations, the interaction of a single dislocation and a spherical cavity is now simulated using a DDD discrete dislocation dynamics model. The simulation accounts for the non-Schmidt effect induced by the bcc structure of Fe through local rules derived from MD simulations [3]. The cavity is introduced in the simulation by computing the image forces using a finite element technique. The effective stress applied on the dislocation is then obtained as the superimposition of the applied stress field, the image stress field and the internal stresses. Note that such a model only uses elasticity theory and no core effect of dislocations is taken into account. One of the objectives of this work is to check whether elasticity is responsible of the behaviour observed by MD. Several cases are tested. First an edge dislocation in a (110) plane is pushed against the cavity under a pure shear loading. The local reaction of the dislocations and the cavity are compared to the MD simulations. Then, the case of a screw dislocation is studied. Finally, other loading

  19. Ipsilateral open anterior hip dislocation and open posterior elbow dislocation in an adult

    Directory of Open Access Journals (Sweden)

    Kumar Sunil

    2014-02-01

    Full Text Available 【Abstract】Open anterior dislocation of the hip is a very rare injury, especially in adults. It is a hyperabduction, external rotation and extension injury. Its combination with open posterior dislocation of the elbow has not been described in English language-based medical literature. Primary resuscitation, debridement, urgent reduction of dislocation, and adequate antibiotic support resulted in good clinical outcome in our patient. At 18 months follow-up, no signs of avascular necrosis of the femoral head or infection were observed.

  20. Posterior treatment of delayed traumatic atlantoaxial joint dislocation with apofix internal fixation

    International Nuclear Information System (INIS)

    Qing Wei; Jiang Weimin; Shi Jinhui; Li Xuefeng; Yang Huilin; Tang Tiansi

    2010-01-01

    Objective: To assess the effect of posterior fixation and fusion with Apofix device for the treatment of delayed traumatic atlantoaxial joint dislocation. Methods: Eighteen patients with delayed traumatic atlantoaxial joint dislocation were included. Posterior fixation and fusion with Apofix device were performed. First step was one or two week skull traction. After the atlantoaxial joint dislocation had been reduced, the posterior fixation and fusion with Apofix was performed. Using local anaesthesia, atlantoaxial interval and posterior structure of atlas and dentata were exposed by midline operative approach. Apofix interlaminar clamps were placed at posterior arch of atlas and odontoid vertebral laminae, autologous iliac bone graft was placed for fusion. Then the device to proper position was pressurized and items locked. Results: All of the patients were followed up, the mean follow-up period was 38 months (13 ∼ 84 months). Fifteen patients obtained complete reduction, the others were partial reduction. Seventeen patients had successful fusion after 3 or 4 months, only 1 patient who had partial reduction had internal fixation loose and nonfusion, leading to recurrence of atlantoaxial joint dislocation. An occipitocervical fusion surgery was performed on this patient. As to neurological assessment, 16 patients had neurological deficit before operation, while 6 of them recovered completely after operation, another 10 patients' neurological status improved significantly. JOA score was improved from 9.5 pre-operative to 15.8 post-operative. Conclusion: Apofix internal fixation and fusion seems to be feasible in treatment of delayed traumatic atlantoaxial joint dislocation. Successful reduction before operation and proper treatment after operation is also important. (authors)

  1. Riemann–Cartan Geometry of Nonlinear Dislocation Mechanics

    KAUST Repository

    Yavari, Arash; Goriely, Alain

    2012-01-01

    but vanishing non-metricity. Torsion of the material manifold is identified with the dislocation density tensor of nonlinear dislocation mechanics. Using Cartan's moving frames we construct the material manifold for several examples of bodies with distributed

  2. Dislocation unpinning model of acoustic emission from alkali halide ...

    Indian Academy of Sciences (India)

    The present paper reports the dislocation unpinning model of acoustic emis- sion (AE) from ... Acoustic emission; dislocation; alkali halide crystals; plastic deformation. ..... [5] T Nishimura, A Tahara and T Kolama, Jpn. Metal Inst. 64, 339 (2000).

  3. Observation of dipole bands in 144Sm

    International Nuclear Information System (INIS)

    Raut, R.; Ganguly, S.; Kshetri, R.; Banerjee, P.; Bhattacharya, S.; Dasmahapatra, B.; Mukherjee, A.; Sahasarkar, M.; Goswami, A.; Basu, S.K.; Bhattacharjee, T.; Mukherjee, G.; Chakraborty, A.; Ghughre, S.S.; Krishichayan; Mukhopadhyay, S.; Gangopadhyay, G.; Singh, A.K.

    2007-01-01

    The nucleus 144 Sm (Z=62, N=82), with its proximity to the shell closure and possibilities of particles and holes occupying high j orbitals, following appropriate excitations, is a suitable system for observation of dipole (MR) bands

  4. Plasmonic functionalities based on detuned electrical dipoles

    DEFF Research Database (Denmark)

    Pors, Anders Lambertus; Nielsen, Michael Grøndahl; Bozhevolnyi, Sergey I.

    2013-01-01

    We introduce and demonstrate the concept of detuned electrical dipoles (DED) that originates from the plasmonic realization of the dressed-state picture of electromagnetically induced transparency in atomic physics. Numerically and experimentally analyzing DED metamaterials consisting of unit cells...

  5. A sum rule calculation of the neutron electric dipole moment from a quark chromoelectric dipole coupling

    International Nuclear Information System (INIS)

    Kogan, I.I.; Wyler, D.

    1992-01-01

    The neutron electric dipole moment (NEDM) from a quark chromoelectric dipole moment is calculated using a QCD sumrule approach. We demonstrate that leading contributions to the NEDM come from induced condensates (quark and quark-gluon condensate magnetic susceptibilities) which are also determined. Other possible contributions to the NEDM such as a quark electric dipole moment or a triple gluon operator are briefly discussed. (orig.)

  6. Coarse-grained elastodynamics of fast moving dislocations

    International Nuclear Information System (INIS)

    Xiong, Liming; Rigelesaiyin, Ji; Chen, Xiang; Xu, Shuozhi; McDowell, David L.; Chen, Youping

    2016-01-01

    The fundamental mechanism of dynamic plasticity in metallic materials subjected to shock loading remains unclear because it is difficult to obtain the precise information of individual fast moving dislocations in metals from the state-of-the-art experiments. In this work, the dynamics of sonic dislocations in anisotropic crystalline materials is explored through a concurrent atomistic-continuum modeling method. We make a first attempt to characterize the complexity of nonuniformly moving dislocations in anisotropic crystals from atomistic to microscale, including the energy intensities as well as the wavelengths of acoustic phonons emitted from sonic dislocations, and the velocity-dependent stress fluctuations around the core of nonuniformly moving dislocations. Instantaneous dislocation velocities and phonon drag effects on the dislocation motions are quantified and analyzed. Mach cones in a V-shaped pattern of the phonon wave-fronts are observed in the wake of the sonic dislocations. Analysis of simulation results based on a wavelet transform show that the faster a dislocation is moving, the longer the emitted phonon wavelength. The dislocation velocity drops dramatically with the occurrence of the interactions between dislocations and phonon waves reflected from the boundaries of specimens. The concurrent atomistic-continuum modeling framework is demonstrated to be the first multiscale method that explicitly treats the strong coupling between the long-range elastic fields away from the dislocation core, the highly nonlinear time-dependent stress field within the core, and the evolutions of the atomic-scale dislocation core structures. As such, it is shown that this method is capable in predicting elastodynamics of dislocations in the presence of inertia effects associated with sonic dislocations in micron-sized anisotropic crystalline materials from the atomic level, which is not directly accessible to the recent elastodynamic discrete dislocation model.

  7. Noncommutative QED and anomalous dipole moments

    International Nuclear Information System (INIS)

    Riad, I.F.; Sheikh-Jabbari, M.M.

    2000-09-01

    We study QED on noncommutative spaces, NCQED. In particular we present the detailed calculation for the noncommutative electron-photon vertex and show that the Ward identity is satisfied. We discuss that in the noncommutative case moving electron will show electric dipole effects. In addition, we work out the electric and magnetic dipole moments up to one loop level. For the magnetic moment we show that noncommutative electron has an intrinsic (spin independent) magnetic moment. (author)

  8. Colour dipoles and virtual Compton scattering

    International Nuclear Information System (INIS)

    McDermott, M.

    2002-01-01

    An analysis of Deeply Virtual Compton Scattering (DVCS) is made within the colour dipole model. We compare and contrast two models for the dipole cross-section which have been successful in describing structure function data. Both models agree with the available cross section data on DVCS from HERA. We give predictions for various azimuthal angle asymmetries in HERA kinematics and for the DVCS cross section in the THERA region. (orig.)

  9. Electric Dipole Echoes in Rydberg Atoms

    International Nuclear Information System (INIS)

    Yoshida, S.; Reinhold, C. O.; Burgdoerfer, J.; Zhao, W.; Mestayer, J. J.; Lancaster, J. C.; Dunning, F. B.

    2007-01-01

    We report the first observation of echoes in the electric dipole moment of an ensemble of Rydberg atoms precessing in an external electric field F. Rapid reversal of the field direction is shown to play a role similar to that of a π pulse in NMR in rephasing a dephased ensemble of electric dipoles resulting in the buildup of an echo. The mechanisms responsible for this are discussed with the aid of classical trajectory Monte Carlo simulations

  10. Magneto-Electric Dipole Antenna Arrays

    OpenAIRE

    Gupta, Shulabh; Jiang, Li Jun; Caloz, Christophe

    2014-01-01

    A planar magneto-electric (ME) dipole antenna array is proposed and demonstrated by both full-wave analysis and experiments. The proposed structure leverages the infinite wavelength propagation characteristic of composite right/left-handed (CRLH) transmission lines to form high-gain magnetic radiators combined with radial conventional electric radiators, where the overall structure is excited by a single differential feed. The traveling-wave type nature of the proposed ME-dipole antenna enabl...

  11. High field dipole magnet design concepts

    International Nuclear Information System (INIS)

    Nicol, T.H.

    1988-12-01

    High field dipole magnets will play a crucial role in the development of future accelerators whether at Fermilab or elsewhere. This paper presents conceptual designs for two such dipoles; 6.6 and 8.8 Tesla, with special focus on their suitability for upgrades to the Fermilab Tevatron. Descriptions and cross-sectional views will be presented as will preliminary estimates of heat loads and costs. 3 refs., 2 figs., 2 tabs

  12. Dislocation Microstructures in Fatiqued Copper Polycrystals

    DEFF Research Database (Denmark)

    Winter, A.T.; Pedersen, Ole Bøcker; Rasmussen, K.V.

    1981-01-01

    Dislocation structures characteristic of persistent slip bands were observed in the interior of polycrystalline copper after fatigue. At low strain amplitudes, within the plateau on the cyclic stress-strain curve, only structures identical to those seen in single crystals were observed. This allows...

  13. Completion of a Dislocated Metric Space

    Directory of Open Access Journals (Sweden)

    P. Sumati Kumari

    2015-01-01

    Full Text Available We provide a construction for the completion of a dislocated metric space (abbreviated d-metric space; we also prove that the completion of the metric associated with a d-metric coincides with the metric associated with the completion of the d-metric.

  14. Frozen shoulder or missed posterior dislocation?

    African Journals Online (AJOL)

    initial diagnosis and management. ... D Leijnen,1,2 MD, MMed (Sports Med); J T Viljoen,1 BSc (Physio), MPhil (Exercise Sci); J H Kirby,1 MB ChB, MSc (Sports Med); ... diagnosis of posterior shoulder dislocation at the time of injury could.

  15. Dislocation defect interaction in irradiated Cu

    International Nuclear Information System (INIS)

    Schaeublin, R.; Yao, Z.; Spaetig, P.; Victoria, M.

    2005-01-01

    Pure Cu single crystals irradiated at room temperature to low doses with 590 MeV protons have been deformed in situ in a transmission electron microscope in order to identify the basic mechanisms at the origin of hardening. Cu irradiated to 10 -4 dpa shows at room temperature a yield shear stress of 13.7 MPa to be compared to the 8.8 MPa of the unirradiated Cu. Irradiation induced damage consists at 90% of 2 nm stacking fault tetrahedra, the remaining being dislocation loops and unidentified defects. In-situ deformation reveals that dislocation-defect interaction can take several forms. Usually, dislocations pinned by defects bow out under the applied stress and escape without leaving any visible defect. From the escape angles obtained at 183 K, an average critical stress of 100 MPa is deduced. In some cases, the pinning of dislocations leads to debris that are about 20 nm long, which formation could be recorded during the in situ experiment

  16. Missed isolated volar dislocation of the scaphoid

    DEFF Research Database (Denmark)

    Kolby, Lise; Larsen, Søren; Jørring, Stig

    2007-01-01

    A patient presented with volar dislocation of the scaphoid, the diagnosis of which had been missed for two weeks. He was treated with open reduction through a combined volar and dorsal approach with decompression of the median nerve, internal fixation, and a cast for eight weeks. One year postope...... postoperatively the functional result was good. A radiograph showed no sign of avascular necrosis....

  17. Tailoring surgical management of dislocated clavicle fractures

    NARCIS (Netherlands)

    Wijdicks, F.J.G.

    2013-01-01

    In this thesis literature research and clinical studies are presented to assist physicians in the decision making process for surgical treatment of dislocated midshaft clavicle fractures (DMCF). In Chapter 1 an introduction is given regarding the background, aim and outline of this thesis. Chapter 2

  18. Screening for congenital dislocation of the hip

    International Nuclear Information System (INIS)

    Fendel, H.

    1987-01-01

    Although the prevalence of (idiopathic) congenital dislocation of the hip (CDH) within the Member States of the European Community is not exactly known, it must be considered as a major problem of public health care and protection. By assessment of available data one can assume that between 1 and 2% of all newborns have dislocation or instability of one or both hips. There is a female predominance of 4:1 and some risk factors are known. The reasons of a higher prevalence in some areas are not yet well understood. Most of instable hips will spontaneously become stable within the first days or weeks of life. However, a considerable number of infants (less than 1%) will remain with instable hips which may dislocate. Dislocation either present at birth or as a result of persistent instability leads to subsequent hip deformation. This is a serious event for each affected individual, and is a heavy load on health care and social costs for the public. Treatment of CDH is easy and usually effective when started early, i.e. before the fourth month of life. The earlier treatment is started the easier, shorter, safer and less expensive it is and its impairment on child development and mother-child interaction can be held to a minimum. Screening for CDH is therefore the most important part of health protection in early infancy. However, this paper concludes that neither sonography nor X-ray examinations are appropriate for CDH screening

  19. Dislocation dynamics in Al-Li alloys: mean jump distance and activation length of moving dislocations

    International Nuclear Information System (INIS)

    De Hosson, J.Th.M.; Huis Int Veld, A.

    1984-01-01

    It is pointed out that aluminum-lithium based alloys offer considerable promise for structural applications, especially in the aerospace industry. This promise is related to the potential for high strength in combination with a density which is lower than that found in conventional aluminum alloys. In addition, the modulus of elasticity is higher than corresponding values in conventional aluminum alloys. A nuclear magnetic resonance study of the mechanism of dislocation motion in Al-2.2 wt pct Li is reported. Information about the effective mean jump distance of mobile dislocations is provided by in situ nuclear spin relaxation measurements. The activation length of mobile dislocations has been obtained from strain-rate change experiments on Al-2.2 wt pct Li. The considered study shows that pulsed nuclear magnetic resonance is a complementary new technique for the study of moving dislocations in Al-Li alloys. 28 references

  20. Radiated energy of electric and magnetic dipoles located inside or outside a sphere

    International Nuclear Information System (INIS)

    Romanov, N.P.

    1986-01-01

    Expressions for the electromagnetic field of elementary electric and magnetic radiators (dipoles) in the presence of a sphere are presented. The field representations in the form of expansions in vector spherical wave functions together with the earlier-obtained expressions for the energy flux of partial waves permits one to compute the energy flux of these dipoles in any spherical region with the center coinciding with the center of the sphere. An analysis of particular cases shows that for nonabsorbing media the ratio of the energies of the inner and outer dipoles, having the same amplitude and located near the surface of the sphere, is independent of the radius of the sphere and is determined only by the relative refractive index and relative magnetic permeability. A model of elementary radiators is described for the interpretation of Raman scattering and luminescence

  1. Dislocation Processes and Frictional Stability of Faults

    Science.gov (United States)

    Toy, V. G.; Mitchell, T. M.; Druiventak, A.

    2011-12-01

    The rate dependence of frictional processes in faults in quartzofeldspathic crust is proposed to change at c. 300°C, because above this temperature asperity deformation can be accommodated by crystal plastic processes. As a consequence, the real fault contact area increases and the fault velocity strengthens. Conversely, faults at lower temperatures are velocity weakening and therefore prone to earthquake slip. We have investigated whether dislocation processes are important around faults in quartzites on seismic timescales, by inducing fault slip on a saw cut surface in novaculite blocks. Deformation was carried out at 450°C and 600°C in a Griggs apparatus. Slip rates of 8.3 x 10-7s-1 allowed total slip, u, of 0.5mm to be achieved in c. 10 minutes. Failure occurred at peak differential stresses of ~1.7 GPa and 1.4 GPa respectively, followed by significant weakening. Structures of the novaculite within and surrounding the fault surface were examined using EBSD, FIB-SEM and TEM to elucidate changes to their dislocation substructure. In the sample deformed at 450°C, a ~50μm thick layer of amorphous / non-crystalline silica was developed on the saw-cut surface during deformation. Rare clasts of the wall rock are preserved within this material. The surrounding sample is mostly composed of equant quartz grains of 5-10μm diameter that lack a preferred orientation, contain very few intercrystalline dislocations, and are divided by organised high angle grain boundaries. After deformation, most quartz grains within the sample retain their starting microstructure. However, within ~10μm of the sliding surface, dislocations are more common, and these are arranged into elongated, tangled zones (subgrain boundaries?). Microfractures are also observed. These microstructures are characteristic of deformation accommodated by low temperature plasticity. Our preliminary observations suggest that dislocation processes may be able to accommodate some deformation around fault

  2. Hydrogen diffusion in the elastic fields of dislocations in iron

    Energy Technology Data Exchange (ETDEWEB)

    Sivak, A. B., E-mail: Sivak-AB@nrcki.ru; Sivak, P. A. [National Research Centre Kurchatov Institute (Russian Federation); Romanov, V. A.; Chernov, V. M. [National Research Tomsk State University (Russian Federation)

    2016-12-15

    The effect of dislocation stress fields on the sink efficiency thereof is studied for hydrogen interstitial atoms at temperatures of 293 and 600 K and at a dislocation density of 3 × 10{sup 14} m{sup –2} in bcc iron crystal. Rectilinear full screw and edge dislocations in basic slip systems 〈111〉(110), 〈111〉(112), 〈100〉(100), and 〈100〉(110) are considered. Diffusion of defects is simulated by means of the object kinetic Monte Carlo method. The energy of interaction between defects and dislocations is calculated using the anisotropic theory of elasticity. The elastic fields of dislocations result in a less than 25% change of the sink efficiency as compared to the noninteracting linear sink efficiency at a room temperature. The elastic fields of edge dislocations increase the dislocation sink efficiency, whereas the elastic fields of screw dislocations either decrease this parameter (in the case of dislocations with the Burgers vector being 1/2〈111〉) or do not affect it (in the case of dislocations with the Burgers vector being 〈100〉). At temperatures above 600 K, the dislocations affect the behavior of hydrogen in bcc iron mainly owing to a high binding energy between the hydrogen atom and dislocation cores.

  3. Nanoscale dislocation shear loops at static equilibrium and finite temperature

    Science.gov (United States)

    Dang, Khanh; Capolungo, Laurent; Spearot, Douglas E.

    2017-12-01

    Atomistic simulations are used to determine the resolved shear stress necessary for equilibrium and the resulting geometry of nanoscale dislocation shear loops in Al. Dislocation loops with different sizes and shapes are created via superposition of elemental triangular dislocation displacement fields in the presence of an externally imposed shear stress. First, a bisection algorithm is developed to determine systematically the resolved shear stress necessary for equilibrium at 0 K. This approach allows for the identification of dislocation core structure and a correlation between dislocation loop size, shape and the computed shear stress for equilibrium. It is found, in agreement with predictions made by Scattergood and Bacon, that the equilibrium shape of a dislocation loop becomes more circular with increasing loop size. Second, the bisection algorithm is extended to study the influence of temperature on the resolved shear stress necessary for stability. An approach is presented to compute the effective lattice friction stress, including temperature dependence, for dislocation loops in Al. The temperature dependence of the effective lattice friction stress can be reliably computed for dislocation loops larger than 16.2 nm. However, for dislocation loops smaller than this threshold, the effective lattice friction stress shows a dislocation loop size dependence caused by significant overlap of the stress fields on the interior of the dislocation loops. Combined, static and finite temperature atomistic simulations provide essential data to parameterize discrete dislocation dynamics simulations.

  4. Electron-dislocation interaction at low temperatures. Progress report

    International Nuclear Information System (INIS)

    1978-01-01

    The interaction of mobile dislocations with electrons in copper and copper alloys has shown that dislocation motion in copper, at low temperature, can be treated as an analog of an underdamped oscillator. We have also shown that the viscous drag on mobile dislocations in type II superconductors can be treated as an acoustic attenuation of an elastic wave

  5. Effect of dislocations on superconductivity. O vliyanii dislokatsiy na sverkhrpovodimost'

    Energy Technology Data Exchange (ETDEWEB)

    Agap' ev, B D; Bytsenko, A A; Sukhanov, S A

    1976-01-01

    Electron-dislocation interaction is analyzed here. The effect of dislocations on the superconductor characteristics is determined according to the Ginzburg-Landau method. Appreciable changes in the stability of the superconductive state are found to occur in the vicinity of dislocations.

  6. An irreducible ankle fracture dislocation: the Bosworth injury

    NARCIS (Netherlands)

    Schepers, Tim; Hagenaars, Tjebbe; den Hartog, Dennis

    2012-01-01

    Irreducible fracture dislocations of the ankle are rare and represent true orthopedic emergencies. We present a case of a fracture dislocation that was irreducible owing to a fixed dislocation of the proximal fibular fragment posterior to the lateral ridge of the tibia. This particular type of

  7. Temporomandibular joint dislocation in an epileptic and mentally ...

    African Journals Online (AJOL)

    Theories regarding the pathogenesis of TMJ dislocation propose laxity of TMJ ligaments or capsule, excessive activity of the lateral pterygoid muscle (LPM)and erosion of the eminence'. TMJ dislocation can occur in an anterior, posterior, lateral and superior direction'. Clinical presentation of dislocated TMJ includes inability ...

  8. Lack of experience is a significant factor in the missed diagnosis of perilunate fracture dislocation or isolated dislocation

    Directory of Open Access Journals (Sweden)

    Ilker Çolak

    2018-01-01

    Conclusion: The results of this study indicated that lack of experience was the most important factor in the misdiagnosis of perilunate fracture dislocation or isolated dislocation. Level of Evidence: Level IV, diagnostic study.

  9. Interaction of 〈1 0 0〉 dislocation loops with dislocations studied by dislocation dynamics in α-iron

    Energy Technology Data Exchange (ETDEWEB)

    Shi, X.J.; Dupuy, L. [CEA, DEN, SRMA, F-91191 Gif-sur-Yvette (France); Devincre, B. [Laboratoire d’Etude des Microstructures, CNRS-ONERA, 29 av. de la Division Leclerc, 92322 Châtillon Cedex (France); Terentyev, D. [SCK–CEN, Nuclear Materials Science Institute, Boeretang 200, B-2400 Mol (Belgium); Vincent, L. [CEA, DEN, SRMA, F-91191 Gif-sur-Yvette (France)

    2015-05-15

    Highlights: • Interactions between edge dislocations and radiation-induced loops were studied by dislocation dynamics. • Dislocation dynamics results are directly compared to molecular dynamics results. • The complex elementary reactions are successfully reproduced. • The critical shear stress to overcome individual loops if reproduced quantitatively. - Abstract: Interstitial dislocation loops with Burgers vector of 〈1 0 0〉 type are formed in α-iron under neutron or heavy ion irradiation. As the density and size of these loops increase with radiation dose and temperature, these defects are thought to play a key role in hardening and subsequent embrittlement of iron-based steels. The aim of the present work is to study the pinning strength of the loops on mobile dislocations. Prior to run massive Dislocation Dynamics (DD) simulations involving experimentally representative array of radiation defects and dislocations, the DD code and its parameterization are validated by comparing the individual loop–dislocation reactions with those obtained from direct atomistic Molecular Dynamics (MD) simulations. Several loop–dislocation reaction mechanisms are successfully reproduced as well as the values of the unpinning stress to detach mobile dislocations from the defects.

  10. Dislocation Structure and Mobility in Hcp Rare-Gas Solids: Quantum versus Classical

    Directory of Open Access Journals (Sweden)

    Santiago Sempere

    2018-01-01

    Full Text Available We study the structural and mobility properties of edge dislocations in rare-gas crystals with the hexagonal close-packed (hcp structure by using classical simulation techniques. Our results are discussed in the light of recent experimental and theoretical studies on hcp 4 He, an archetypal quantum crystal. According to our simulations classical hcp rare-gas crystals present a strong tendency towards dislocation dissociation into Shockley partials in the basal plane, similarly to what is observed in solid helium. This is due to the presence of a low-energy metastable stacking fault, of the order of 0.1 mJ/m 2 , that can get further reduced by quantum nuclear effects. We compute the minimum shear stress that induces glide of dislocations within the hcp basal plane at zero temperature, namely, the Peierls stress, and find a characteristic value of the order of 1 MPa. This threshold value is similar to the Peierls stress reported for metallic hcp solids (Zr and Cd but orders of magnitude larger than the one estimated for solid helium. We find, however, that in contrast to classical hcp metals but in analogy to solid helium, glide of edge dislocations can be thermally activated at very low temperatures, T∼10 K, in the absence of any applied shear stress.

  11. Discrete dislocation plasticity analysis of loading rate-dependent static friction.

    Science.gov (United States)

    Song, H; Deshpande, V S; Van der Giessen, E

    2016-08-01

    From a microscopic point of view, the frictional force associated with the relative sliding of rough surfaces originates from deformation of the material in contact, by adhesion in the contact interface or both. We know that plastic deformation at the size scale of micrometres is not only dependent on the size of the contact, but also on the rate of deformation. Moreover, depending on its physical origin, adhesion can also be size and rate dependent, albeit different from plasticity. We present a two-dimensional model that incorporates both discrete dislocation plasticity inside a face-centred cubic crystal and adhesion in the interface to understand the rate dependence of friction caused by micrometre-size asperities. The friction strength is the outcome of the competition between adhesion and discrete dislocation plasticity. As a function of contact size, the friction strength contains two plateaus: at small contact length [Formula: see text], the onset of sliding is fully controlled by adhesion while for large contact length [Formula: see text], the friction strength approaches the size-independent plastic shear yield strength. The transition regime at intermediate contact size is a result of partial de-cohesion and size-dependent dislocation plasticity, and is determined by dislocation properties, interfacial properties as well as by the loading rate.

  12. Analysis of partially pulsating fatigue process on carbon steel with microstructural observation

    International Nuclear Information System (INIS)

    Shimano, Hiroyuki; Faiz, M. Khairi; Hara, Asato; Yoshizumi, Kyoko; Yoshida, Makoto; Horibe, Susumu

    2016-01-01

    Pulsating low-cycle fatigue processes, up to the present, have been divided into three states: the transient state, steady state, and accelerating state of ratcheting. In our previous work, we suggested that fatigue behavior of pulsating fatigue process should be classified into five stages in which the plastic strain amplitude and the ratcheting strain rate are plotted on the X and Y axis, respectively. In this study, at the condition of R=−0.3 (partially pulsating fatigue), the change in the plastic strain amplitude and ratcheting strain rate for each cycle to failure was examined on AISI 1025 carbon steel. The dislocation substructure was examined using transmission electron microscopy (TEM) for each stage, except for stage I. It was also demonstrated that the fatigue process can be divided into five stages: stage I corresponds to the un-pinning of dislocations from the Cottrell atmosphere and propagation of the Luders band. Stage II corresponds to the restriction of dislocation movement by dislocation tangles. Stage III corresponds to the formation of dislocation cells. Stage IV corresponds to the promotion of the to-and-fro (back-and-forth) motion of dislocations by a re-arrangement of the dislocations in the cells. Stage V corresponds to the release of dislocation movement by the collapse of dislocation cells.

  13. Analysis of partially pulsating fatigue process on carbon steel with microstructural observation

    Energy Technology Data Exchange (ETDEWEB)

    Shimano, Hiroyuki, E-mail: tales-of-destiny@akane.waseda.jp [Department of Modern Mechanical Engineering, Graduate School of Creative Science and Engineering, Waseda University, 3-4-1 Shinjyuku-ku Okubo, Tokyo 169-8555 (Japan); Faiz, M. Khairi; Hara, Asato; Yoshizumi, Kyoko [Department of Modern Mechanical Engineering, Graduate School of Creative Science and Engineering, Waseda University, 3-4-1 Shinjyuku-ku Okubo, Tokyo 169-8555 (Japan); Yoshida, Makoto [Department of Modern Mechanical Engineering, Graduate School of Creative Science and Engineering, Waseda University, 3-4-1 Shinjyuku-ku Okubo, Tokyo 169-8555 (Japan); Kagami Memorial Research Institute for Materials Science and Technology, Waseda University, 2-8-26, Nishi-Waseda, Shinjyuku-ku, Tokyo 169-0051 (Japan); Horibe, Susumu [Department of Modern Mechanical Engineering, Graduate School of Creative Science and Engineering, Waseda University, 3-4-1 Shinjyuku-ku Okubo, Tokyo 169-8555 (Japan)

    2016-01-10

    Pulsating low-cycle fatigue processes, up to the present, have been divided into three states: the transient state, steady state, and accelerating state of ratcheting. In our previous work, we suggested that fatigue behavior of pulsating fatigue process should be classified into five stages in which the plastic strain amplitude and the ratcheting strain rate are plotted on the X and Y axis, respectively. In this study, at the condition of R=−0.3 (partially pulsating fatigue), the change in the plastic strain amplitude and ratcheting strain rate for each cycle to failure was examined on AISI 1025 carbon steel. The dislocation substructure was examined using transmission electron microscopy (TEM) for each stage, except for stage I. It was also demonstrated that the fatigue process can be divided into five stages: stage I corresponds to the un-pinning of dislocations from the Cottrell atmosphere and propagation of the Luders band. Stage II corresponds to the restriction of dislocation movement by dislocation tangles. Stage III corresponds to the formation of dislocation cells. Stage IV corresponds to the promotion of the to-and-fro (back-and-forth) motion of dislocations by a re-arrangement of the dislocations in the cells. Stage V corresponds to the release of dislocation movement by the collapse of dislocation cells.

  14. Molecular dynamics study of dislocation cores in copper: structure and diffusion at high temperatures

    International Nuclear Information System (INIS)

    Huang, Jin

    1989-01-01

    The variation of the core structure of an easy glide dislocation with temperature and its influence on the stacking fault energy (γ) have been investigated for the first time by molecular-dynamics simulation in copper. The calculations have been performed at various temperatures, using an ab-initio pseudo-potential. Our results show that the core of the Shockley partials, into which the perfect edge dislocation dissociates, becomes increasingly extended as temperature increases. However their separation remains constant. The calculated energy values of the infinite extension stacking fault and the ribbon fault between the partials are quite different, but the evolution of the core structure does not affect the temperature dependence of the latter. We have found that a high disorder appears in the core region when temperature increases due to important anharmonicity effects of the atomic vibrations. The core structure remains solid-like for T m (T m : melting point of bulk) in spite of the high disorder. Above T m , the liquid nucleus germinates in the core region, and then propagates into the bulk. In addition we studied the mobility of vacancies and interstitials trapped on the partials. Although fast diffusion is thought to occur exclusively in a pipe surrounding the dislocation core, in the present study a quasi two-dimensional diffusion is observed for both defects not only in the cores but also in the stacking fault ribbon. On the opposite of current assumptions, the activation energy for diffusion is found to be identical for both defects, which may therefore comparably contribute to mass transport along the dislocations. (author) [fr

  15. Stress-free states of continuum dislocation fields : Rotations, grain boundaries, and the Nye dislocation density tensor

    NARCIS (Netherlands)

    Limkumnerd, Surachate; Sethna, James P.

    We derive general relations between grain boundaries, rotational deformations, and stress-free states for the mesoscale continuum Nye dislocation density tensor. Dislocations generally are associated with long-range stress fields. We provide the general form for dislocation density fields whose

  16. Work softening in nanocrystalline materials induced by dislocation annihilation

    DEFF Research Database (Denmark)

    Ungar, Tamas; Li, Li; Tichy, Geza

    2011-01-01

    Cold rolling reduces the quantity of dislocation densities in Ni–18% Fe alloys prepared by electrochemical deposition. The dislocation density evolution proposed earlier for the linearly decreasing work-hardening rate during stage III is revisited. The solution of the differential equation predicts...... that when the initial dislocation density is smaller or larger than the saturation value, then the dislocation density will increase or decrease during further plastic deformation. The predictions are verified by experimental values of dislocation densities determined by X-ray line-profile analysis....

  17. Application of positron-electron annihilation method for determination of dislocation splitting width in d-transition metals

    International Nuclear Information System (INIS)

    Dekhtyar, A.I.; Kozyrskij, G.Ya.; Kononenko, V.A.

    1978-01-01

    A method for the study of the dislocation structure in d-transition metals with the application of experimental data on annihilation of electron-positron pairs is suggested. The method is based on finding the density of partially collectivized d- electrons using the technique of expanding the angular distribution of the positron-electron annihilation. In the wave vectors space, the concept of a pseudosphere was introduced, whose radius k'sub(F) is determined by the number of d-electrons. It was assumed that k'sub(F) is a parameter of the potential of effective atomic interaction in d-metals. The interaction energy between nuclei of partial dislocations was accounted for as an oscillating potential between parallel atom rows. Such a consideration makes it possible to correct the position of a partial dislocation in the neighbourhood of a wide minimum of interaction energy. The possibilities of the method for determining the splitting width of edge dislocations in various d-metals and their alloys (Mo, Ni, Fe, Nb) is shown. Using pure and doped Ni, the decrease of the packing defect energy was traced with the increase of Al content

  18. Dynamic dipole-dipole interactions between excitons in quantum dots of different sizes

    DEFF Research Database (Denmark)

    Matsueda, Hideaki; Leosson, Kristjan; Xu, Zhangcheng

    2004-01-01

    A model of the resonance dynamic dipole-dipole interaction between excitons confined in quantum dots (QDs) of different sizes at close enough distance is given in terms of parity inheritance and exchange of virtual photons. Microphotoluminescence spectra of GaAs-AlGaAs coupled QDs are proposed to...

  19. Dynamic Dipole-Dipole Interactions between Excitons in Quantum Dots of Different Sizes

    DEFF Research Database (Denmark)

    Matsueda, Hideaki; Leosson, Kristjan; Xu, Zhangcheng

    2005-01-01

    Micro-photoluminescence spectra of GaAs/AlGaAs coupled quantum dots (QDs) are given, and proposed to be analyzed by our resonance dynamic dipole-dipole interaction (RDDDI) model, based on parity inheritance and exchange of virtual photons among QDs of different sizes....

  20. BILATERAL PATHOLOGICAL HIP DISLOCATION IN CHILDREN

    Directory of Open Access Journals (Sweden)

    Yuriy E. Garkavenko

    2017-03-01

    Full Text Available Introduction. Pathological dislocation of the hip is one of the most severe complications of acute hematogenous osteomyelitis. The program of treatment for children with pathological hip dislocation is complex, but it has been sufficiently developed and implemented very successfully. At the same time, the available literature provides no cases of treating children with bilateral pathological hip dislocations after hematogenous osteomyelitis. There is no information on the incidence of such cases or in regards to remote functional results. Materials and methods. The results of the treatment of 18 children with bilateral pathological dislocation of the hip after hematogenous osteomyelitis are presented, which constituted 23.1% of the total number of patients (78 who underwent surgery in 2000–2016 for the diagnosis of pathological hip dislocation. Both hip joints were surgically operated on in 12 patients, while one hip joint was operated on in 6 patients. To assess the anatomical and functional state of hip joints, the clinical and roentgenological diagnostic techniques were used. Results and discussion. To stabilize and restore the function of the hip joints, 18 children underwent 30 surgical interventions: simple open hip reduction (19 and open hip reduction with hip arthroplasty with one (6 or two (5 demineralized osteochondral allogeneic grafts. The decision regarding the possibility of performing surgical intervention on the second hip joint was made only after a child's check-up examination was complete and after positive information about the anatomical and functional state of the operated hip joint was obtained. According to these criteria, 14 (77.8% children underwent surgical treatment of the second hip joint 1–1.5 years after the course of conservative measures to restore the range of motion in the previously operated hip joint. Over a period of 1–12 years, 17 patients were examined, 10 of which underwent an operation on both

  1. Recombination properties of dislocations in GaN

    Science.gov (United States)

    Yakimov, Eugene B.; Polyakov, Alexander Y.; Lee, In-Hwan; Pearton, Stephen J.

    2018-04-01

    The recombination activity of threading dislocations in n-GaN with different dislocation densities and different doping levels was studied using electron beam induced current (EBIC). The recombination velocity on a dislocation, also known as the dislocation recombination strength, was calculated. The results suggest that dislocations in n-GaN giving contrast in EBIC are charged and surrounded by a space charge region, as evidenced by the observed dependence of dislocation recombination strength on dopant concentration. For moderate (below ˜108 cm-2) dislocation densities, these defects do not primarily determine the average diffusion length of nonequilibrium charge carriers, although locally, dislocations are efficient recombination sites. In general, it is observed that the effect of the growth method [standard metalorganic chemical vapor deposition (MOCVD), epitaxial lateral overgrowth versions of MOCVD, and hydride vapor phase epitaxy] on the recombination activity of dislocations is not very pronounced, although the average diffusion lengths can widely differ for various samples. The glide of basal plane dislocations at room temperature promoted by low energy electron irradiation does not significantly change the recombination properties of dislocations.

  2. Thermally activated dislocation motion including inertial effects in solid solutions

    International Nuclear Information System (INIS)

    Isaac, R.D.

    1977-01-01

    Dislocation motion through an array of obstacles is considered in terms of the potential energy of the dislocation as it moves through the array. The obstacles form a series of potential wells and barriers which can trap the dislocations. The effect of thermal fluctuations and of a viscous drag on the motion of the dislocation is investigated by analogy with Brownian motion in a field of force. The rate of escape of a trapped dislocation is found to depend on the damping coefficient only for a large viscous drag. The probability that a dislocation will be trapped by a well or barrier is found to depend on the damping coefficient for a small viscous drag. This inertial effect determines how far a dislocation will travel after breaking away from an obstacle

  3. Ultrasound as a probe of dislocation density in aluminum

    International Nuclear Information System (INIS)

    Mujica, Nicolás; Cerda, Maria Teresa; Espinoza, Rodrigo; Lisoni, Judit; Lund, Fernando

    2012-01-01

    Graphical abstract: Display Omitted - Abstract: Dislocations are at the heart of the plastic behavior of crystalline materials yet it is notoriously difficult to perform quantitative, non-intrusive measurements of their single or collective properties. Dislocation density is a critical variable that determines dislocation mobility, strength and ductility. On the one hand, individual dislocations can be probed in detail with transmission electron microscopy. On the other hand, their collective properties must be simulated numerically. Here we show that ultrasound technology can be used to measure dislocation density. This development rests on theory—a generalization of the Granato–Lücke theory for the interaction of elastic waves with dislocations—and resonant ultrasound spectroscopy (RUS) measurements. The chosen material is aluminum, to which different dislocation contents were induced through annealing and cold-rolling processes. The dislocation densities obtained with RUS compare favorably with those inferred from X-ray diffraction, using the modified Williamson–Hall method.

  4. Electrical conduction along dislocations in plastically deformed GaN

    Energy Technology Data Exchange (ETDEWEB)

    Kamimura, Y; Yokoyama, T; Oiwa, H; Edagawa, K [Institute of Industrial Science, the University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan); Yonenaga, I, E-mail: yasushi@iis.u-tokyo.ac.jp [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577 (Japan)

    2009-07-15

    Electrical conduction along dislocations in plastically deformed n-GaN single crystals has been investigated by scanning spread resistance microscopy (SSRM). In the SSRM images, many conductive spots have been observed, which correspond to electrical conduction along the dislocations introduced by deformation. Here, the introduced dislocations are b=(a/3)<1overline 210> edge dislocations parallel to the [0001] direction. The current values at the spots normalized to the background current value are larger than 100. Previous works have shown that grown-in edge dislocations in GaN are nonconductive. The high conductivity of the deformation-introduced edge dislocations in the present work suggests that the conductivity depends sensitively on the dislocation core structure.

  5. Inhibition of two-photon absorption due to dipole-dipole interaction in nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Mahi R. [Department of Physics and Astronomy, University of Western Ontario, London, N6A 3K7 (Canada)], E-mail: msingh@uwo.ca

    2008-07-21

    We have investigated the inhibition of two-photon absorption in photonic crystals doped with an ensemble of four-level nanoparticles. The particles are interacting with one another by the dipole-dipole interaction. Dipoles in nanoparticles are induced by a selected transition. Numerical simulations have been performed for an isotropic photonic crystal. Interesting phenomena have been predicted such as the inhibition of the two-photon absorption due to the dipole-dipole interaction. It has also been found that the inhibition effect can be switched on and off by tuning a decay resonance energy within the energy band of the crystal. A theory of dressed states has been used to explain the results.

  6. 2-vertex Lorentzian spin foam amplitudes for dipole transitions

    Science.gov (United States)

    Sarno, Giorgio; Speziale, Simone; Stagno, Gabriele V.

    2018-04-01

    We compute transition amplitudes between two spin networks with dipole graphs, using the Lorentzian EPRL model with up to two (non-simplicial) vertices. We find power-law decreasing amplitudes in the large spin limit, decreasing faster as the complexity of the foam increases. There are no oscillations nor asymptotic Regge actions at the order considered, nonetheless the amplitudes still induce non-trivial correlations. Spin correlations between the two dipoles appear only when one internal face is present in the foam. We compute them within a mini-superspace description, finding positive correlations, decreasing in value with the Immirzi parameter. The paper also provides an explicit guide to computing Lorentzian amplitudes using the factorisation property of SL(2,C) Clebsch-Gordan coefficients in terms of SU(2) ones. We discuss some of the difficulties of non-simplicial foams, and provide a specific criterion to partially limit the proliferation of diagrams. We systematically compare the results with the simplified EPRLs model, much faster to evaluate, to learn evidence on when it provides reliable approximations of the full amplitudes. Finally, we comment on implications of our results for the physics of non-simplicial spin foams and their resummation.

  7. LHC dipoles: the countdown has begun

    CERN Document Server

    Patrice Loiez

    2002-01-01

    At the entrance to the fourth floor corridor of the LHC-MMS (Main Magnets and Superconductors) Group in building 30, the Director-General has unveiled an electronic information panel indicating the number of LHC dipoles still to be delivered and the days remaining to the deadline (30 June 2006). The panel was the idea of Lucio Rossi, leader of the MMS Group, which is responsible for the construction of the dipole magnets. The unveiling ceremony took place on the morning of Friday 11 October 2002, at the end of a drink held to celebrate with MMS group and the LHC top management the exceptional performance of the latest dipoles, built by the French consortium Alstom-Jeumont. They are the first dipoles to achieve a magnetic field of 9 tesla in one go without quenching, thus exceeding the nominal operating field of 8.3 tesla. The challenge is now to increase the production rate from 2 to 35 dipoles per month by 2004 in order to meet the deadline, while maintaining this quality. Photo 01: The Director-General Luci...

  8. Partial Cancellation

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Partial Cancellation. Full Cancellation is desirable. But complexity requirements are enormous. 4000 tones, 100 Users billions of flops !!! Main Idea: Challenge: To determine which cross-talker to cancel on what “tone” for a given victim. Constraint: Total complexity is ...

  9. On low temperature glide of dissociated 〈1 1 0〉 dislocations in strontium titanate

    Science.gov (United States)

    Ritterbex, Sebastian; Hirel, Pierre; Carrez, Philippe

    2018-05-01

    An elastic interaction model is presented to quantify low temperature plasticity of SrTiO3 via glide of dissociated 〈1 1 0〉{1 1 0} screw dislocations. Because 〈1 1 0〉 dislocations are dissociated, their glide, controlled by the kink-pair mechanism at T good quantitative agreement with the observed non-monotonic mechanical behaviour of SrTiO3. This agreement allows to explain the experimental results in terms of a (progressive) change in 〈1 1 0〉{1 1 0} glide mechanism, from simultaneous nucleation of two kink-pairs along both partials at low stress, towards nucleation of single kink-pairs on individual partials if resolved shear stress exceeds a critical value of 95 MPa. High resolved shear stress allows thus for the activation of extra nucleation mechanisms on dissociated dislocations impossible to occur under the sole action of thermal activation. We suggest that stress condition in conjunction with core dissociation is key to the origin of non-monotonic plastic behaviour of SrTiO3 at low temperatures.

  10. Chirality-controlled crystallization via screw dislocations.

    Science.gov (United States)

    Sung, Baeckkyoung; de la Cotte, Alexis; Grelet, Eric

    2018-04-11

    Chirality plays an important role in science from enantiomeric separation in chemistry to chiral plasmonics in nanotechnology. However, the understanding of chirality amplification from chiral building blocks to ordered helical superstructures remains a challenge. Here, we demonstrate that topological defects, such as screw dislocations, can drive the chirality transfer from particle to supramolecular structure level during the crystallization process. By using a model system of chiral particles, which enables direct imaging of single particle incorporation into growing crystals, we show that the crystallization kinetic pathway is the key parameter for monitoring, via the defects, the chirality amplification of the crystalline structures from racemic to predominantly homohelical. We provide an explanation based on the interplay between geometrical frustration, racemization induced by thermal fluctuations, and particle chirality. Our results demonstrate that screw dislocations not only promote the growth, but also control the chiral morphology and therefore the functionality of crystalline states.

  11. Size-dependent plastic deformation characteristics in He-irradiated nanostructured Cu/Mo multilayers: Competition between dislocation-boundary and dislocation-bubble interactions

    International Nuclear Information System (INIS)

    Zhang, J.Y.; Zeng, F.L.; Wu, K.; Wang, Y.Q.; Liang, X.Q.; Liu, G.; Zhang, G.J.; Sun, J.

    2016-01-01

    Nanoindentation methodology was used to investigate the plastic deformation characteristics, including the hardness (H), strain rate sensitivity (SRS, m) and activation volume (V * ), of Cu/Mo nanostructured metallic multilayers (NMMs) with equal layer thickness (h) spanning from 10 to 200 nm before and after He-implantation at room temperature. Compared with the as-deposited Cu/Mo NMMs, the irradiated Cu/Mo samples exhibited the enhanced hardness particularly at great h, which is caused by the bubble-hardening effect. Unlike the as-deposited Cu/Mo NMMs displayed a monotonic increase in SRS (or a monotonic decrease in activation volume) with reducing h, the irradiated Cu/Mo samples manifested an unexpected non-monotonic variation in SRS as well as in activation volume. It was clearly unveiled that the SRS of irradiated Cu/Mo firstly decreased with reducing h down to a critical size of ~50 nm and subsequently increased with further reducing h, leaving a minimum value at the critical h. These phenomena are rationalized by considering a competition between dislocation-boundary and dislocation-bubble interactions. A thermally activated model based on the depinning process of bowed-out partial dislocations was employed to quantitatively account for the size-dependent SRS of Cu/Mo NMMs before and after irradiation. Our findings not only provide fundamental understanding of the effects of radiation-induced defects on plastic characteristics of NMMs, but also offer guidance for their microstructure sensitive design for performance optimization at extremes.

  12. Quasicontinuum analysis of dislocation-coherent twin boundary interaction to provide local rules to discrete dislocation dynamics

    Science.gov (United States)

    Tran, H.-S.; Tummala, H.; Duchene, L.; Pardoen, T.; Fivel, M.; Habraken, A. M.

    2017-10-01

    The interaction of a pure screw dislocation with a Coherent Twin Boundary Σ3 in copper was studied using the Quasicontinuum method. Coherent Twin Boundary behaves as a strong barrier to dislocation glide and prohibits slip transmission across the boundary. Dislocation pileup modifies the stress field at its intersection with the Grain Boundary (GB). A methodology to estimate the strength of the barrier for a dislocation to slip across CTB is proposed. A screw dislocation approaching the boundary from one side either propagates into the adjacent twin grain by cutting through the twin boundary or is stopped and increases the dislocation pileup amplitude at the GB. Quantitative estimation of the critical stress for transmission was performed using the virial stress computed by Quasicontinuum method. The transmission mechanism and critical stress are in line with the literature. Such information can be used as input for dislocation dynamic simulations for a better modeling of grain boundaries.

  13. Traumatic atlantooccipital dislocation injury in children.

    Science.gov (United States)

    Nichols, J; West, J S

    1994-10-01

    The tragedy of trauma turns into triumph when the surgery team members' efforts result in victory for the patient. Nowhere is this more true than in successful pediatric trauma care. Giving a child a second chance at life and the family an opportunity for a new beginning is the highest reward for the trauma team's years of professional training and practice. Traumatic atlantoocipital dislocation injury usually results in death, but recent neurosurgery trauma advances are increasing pediatric survival rates.

  14. Dislocation dynamics simulations in a cylinder

    International Nuclear Information System (INIS)

    Weinberger, Christopher R; Aubry, Sylvie; Cai, Wei; Lee, Seok-Woo

    2009-01-01

    In this work we describe how to perform dislocation dynamics simulations in a cylindrical geometry. An algorithm for computing the image stress is given in detail including methods for handling the singularity. Additional remesh rules address the problems of the cylindrical geometry and the required self consistency with mobility laws. Numerical studies benchmark the accuracy of the algorithms and the importance of handling the singularity correctly.

  15. Irreducible lateral dislocation of the elbow.

    Directory of Open Access Journals (Sweden)

    Chhaparwal M

    1997-01-01

    Full Text Available A rare case of an irreducible post-traumatic lateral dislocation of elbow is presented. The mechanism of injury was fall on a flexed elbow with trauma on its medial aspect resulting in pronation of the forearm. At open reduction, the brachialis muscle was in the form of a tight band which prevented reduction. The ulnar nerve was entrapped in the joint.

  16. Dislocation Concepts in Friction and Wear.

    Science.gov (United States)

    1980-12-01

    geometrica considerations, and other basic facts concerning plastic Drover ties of crystalline materials, a numiber of qualitative and quanI titative... correct but, in connection with cell walls, it is generally erroneous as indicated. Fig. 27 demonstrates this clearly: The dislocation cells make the...is certainly promising. If it is then assumed that it is basically correct , one may be impressed with the underlying simplicity of the mechanisms

  17. Investigating dislocation motion through a field of solutes with atomistic simulations and reaction rate theory

    International Nuclear Information System (INIS)

    Saroukhani, S.; Warner, D.H.

    2017-01-01

    The rate of thermally activated dislocation motion across a field of solutes is studied using traditional and modern atomistically informed rate theories. First, the accuracy of popular variants of the Harmonic Transition State Theory, as the most common approach, is examined by comparing predictions to direct MD simulations. It is shown that HTST predictions are grossly inaccurate due to the anharmonic effect of thermal softening. Next, the utility of the Transition Interface Sampling was examined as the method was recently shown to be effective for predicting the rate of dislocation-precipitate interactions. For dislocation-solute interactions studied here, TIS is found to be accurate only when the dislocation overcomes multiple obstacles at a time, i.e. jerky motion, and it is inaccurate in the unpinning regime where the energy barrier is of diffusive nature. It is then shown that the Partial Path TIS method - designed for diffusive barriers - provides accurate predictions in the unpinning regime. The two methods are then used to study the temperature and load dependence of the rate. It is shown that Meyer-Neldel (MN) rule prediction of the entropy barrier is not as accurate as it is in the case of dislocation-precipitate interactions. In response, an alternative model is proposed that provides an accurate prediction of the entropy barrier. This model can be combined with TST to offer an attractively simple rate prediction approach. Lastly, (PP)TIS is used to predict the Strain Rate Sensitivity (SRS) factor at experimental strain rates and the predictions are compared to experimental values.

  18. Congenital hip dislocation: Radiological screening or diagnosis?

    International Nuclear Information System (INIS)

    Kalifa, G.; Faure, C.

    1987-01-01

    Congenital hip dislocation is a perfect example of public health problems: its incidence is high 0.6, to 2% of newborns in France and an early detection allows an easy and successful treatment. The current situation in our country is not satisfactory for several reasons: - Too many children are treated without reasons because of misleading radiological pictures; - Conversely, some dislocations are discovered only at the walking age, the treatment becoming then more difficult and less effective; - Almost 300,000 radiological examinations of the hip for screening are performed each year and among them 100,000 in newborns. This is not satisfactory as it is commonly admitted now that radiological examination at birth is unreliable and frequently misleading. For all these reasons a special working group has been settled up by the General Direction of Health, including physicians of different practices, from different specialities. The conclusion of this group will be published in a special booklet and can be summarized as follows: The group recommends to perform detection of congenital hip dislocation mainly by the clinical examination. This examination may be difficult but it must be performed very early, the first day of life, repeated several times, at the end of the first week and during the first, second, and third month. Every baby in this country must undergo several clinical examinations up to one year of age

  19. Photon scattering by the giant dipole resonance

    International Nuclear Information System (INIS)

    Bowles, T.J.; Holt, R.J.; Jackson, H.E.; McKeown, R.D.; Specht, J.R.

    1979-01-01

    Although many features of the giant dipole resonance are well known, the coupling between the basic dipole oscillation and other nuclear collective degrees of freedom such as surface vibrations and rotations is poorly understood. This aspect was investigated by elastic and inelastic bremsstrahlung scattering of tagged photons over the energy range 15 to 22 MeV. Target nuclei were 60 Ni, 52 Cr, 56 Fe, 92 Mo, and 96 Mo. Scattering and absorption cross sections are tabulated, along with parameters obtained from a two-Lorentzian analysis of the scattering cross sections; measured spectra are shown. It was necessary to remove Thomson scattering from the experimental results. It was found that coupling to surface vibrations in the giant dipole resonance is much weaker than the dynamic collective model suggests. The elastic scattering cross section for all targets but 60 Ni showed structure that is not evident in the absorption cross section measurement. 12 figures, 2 tables

  20. Perturbative odderon in the dipole model

    International Nuclear Information System (INIS)

    Kovchegov, Yuri V.; Szymanowski, Lech; Wallon, Samuel

    2004-01-01

    We show that, in the framework of Mueller's dipole model, the perturbative QCD odderon is described by the dipole model equivalent of the BFKL equation with a C-odd initial condition. The eigenfunctions and eigenvalues of the odderon solution are the same as for the dipole BFKL equation and are given by the functions E n,ν and χ(n,ν) correspondingly, where the C-odd initial condition allows only for odd values of n. The leading high-energy odderon intercept is given by α odd -1=((2α s N c )/(π))χ(n=1,ν=0)=0 in agreement with the solution found by Bartels, Lipatov and Vacca. We proceed by writing down an evolution equation for the odderon including the effects of parton saturation. We argue that saturation makes the odderon solution a decreasing function of energy

  1. Installation Strategy for the LHC Main Dipoles

    CERN Multimedia

    Fartoukh, Stephane David

    2004-01-01

    All positions in the LHC machine are not equivalent in terms of beam requirements on the geometry and the field quality of the main dipoles. In the presence of slightly or strongly out-of tolerance magnets, a well-defined installation strategy will therefore contribute to preserve or even optimize the performance of the machine. Based on the present status of the production, we have anticipated a list of potential issues (geometry, transfer function, field direction and random b3) which, combined by order of priority, have been taken into account to define a simple but efficient installation algorithm for the LHC main dipoles. Its output is a prescription for installing the available dipoles in sequence while reducing to an absolute minimum the number of holes required by geometry or FQ issues.

  2. Transportation studies: 40-MM collider dipole magnets

    International Nuclear Information System (INIS)

    Daly, E.

    1992-01-01

    Several fully functional 40-mm Collider Dipole Magnets (CDM) were instrumented with accelerometers to monitor shock and vibration loads during transport. The magnets were measured with optical tooling telescopes before and after transport. Changes in mechanical alignment due to shipping and handling were determined. The mechanical stability of the cryogen lines were checked using the same method. Field quality and dipole angle were measured warm before and after transport to determine changes in these parameters. Power spectra were calculated for accelerometers located on the cold mass, vacuum vessel, and trailer bed. Where available, plots of field quality and dipole roll both before and after were created. Shipping loads measured were largest in the vertical direction, where most of the structural deformation of the magnet was evident. It was not clear that magnetic performance was affected by the shipping and handling environment

  3. Perturbative odderon in the dipole model

    Energy Technology Data Exchange (ETDEWEB)

    Kovchegov, Yuri V.; Szymanowski, Lech; Wallon, Samuel

    2004-04-29

    We show that, in the framework of Mueller's dipole model, the perturbative QCD odderon is described by the dipole model equivalent of the BFKL equation with a C-odd initial condition. The eigenfunctions and eigenvalues of the odderon solution are the same as for the dipole BFKL equation and are given by the functions E{sup n,{nu}} and {chi}(n,{nu}) correspondingly, where the C-odd initial condition allows only for odd values of n. The leading high-energy odderon intercept is given by {alpha}{sub odd}-1=((2{alpha}{sub s}N{sub c})/({pi})){chi}(n=1,{nu}=0)=0 in agreement with the solution found by Bartels, Lipatov and Vacca. We proceed by writing down an evolution equation for the odderon including the effects of parton saturation. We argue that saturation makes the odderon solution a decreasing function of energy.

  4. Neutron Electric Dipole Moment from colored scalars⋆

    Directory of Open Access Journals (Sweden)

    Fajfer Svjetlana

    2014-01-01

    Full Text Available We present new contributions to the neutron electric dipole moment induced by a color octet, weak doublet scalar, accommodated within a modified Minimal Flavor Violating framework. These flavor non-diagonal couplings of the color octet scalar might account for an assymmetry of order 3 × 10−3 for aCP(D0 → K−K+ − aCP(D0 → π+π− at tree level. The same couplings constrained by this assymmetry also induce two-loop contributions to the neutron electric dipole moment. We find that the direct CP violating asymmetry in neutral D-meson decays is more constraining on the allowed parameter space than the current experimental bound on neutron electric dipole moment.

  5. Photoelectron spectroscopy and the dipole approximation

    Energy Technology Data Exchange (ETDEWEB)

    Hemmers, O.; Hansen, D.L.; Wang, H. [Univ. of Nevada, Las Vegas, NV (United States)] [and others

    1997-04-01

    Photoelectron spectroscopy is a powerful technique because it directly probes, via the measurement of photoelectron kinetic energies, orbital and band structure in valence and core levels in a wide variety of samples. The technique becomes even more powerful when it is performed in an angle-resolved mode, where photoelectrons are distinguished not only by their kinetic energy, but by their direction of emission as well. Determining the probability of electron ejection as a function of angle probes the different quantum-mechanical channels available to a photoemission process, because it is sensitive to phase differences among the channels. As a result, angle-resolved photoemission has been used successfully for many years to provide stringent tests of the understanding of basic physical processes underlying gas-phase and solid-state interactions with radiation. One mainstay in the application of angle-resolved photoelectron spectroscopy is the well-known electric-dipole approximation for photon interactions. In this simplification, all higher-order terms, such as those due to electric-quadrupole and magnetic-dipole interactions, are neglected. As the photon energy increases, however, effects beyond the dipole approximation become important. To best determine the range of validity of the dipole approximation, photoemission measurements on a simple atomic system, neon, where extra-atomic effects cannot play a role, were performed at BL 8.0. The measurements show that deviations from {open_quotes}dipole{close_quotes} expectations in angle-resolved valence photoemission are observable for photon energies down to at least 0.25 keV, and are quite significant at energies around 1 keV. From these results, it is clear that non-dipole angular-distribution effects may need to be considered in any application of angle-resolved photoelectron spectroscopy that uses x-ray photons of energies as low as a few hundred eV.

  6. Kinetic competitivity between ordering and solute segregation to dislocations in Cu-20% at. Mn

    International Nuclear Information System (INIS)

    Donoso, E.; Varschavsky, A.

    1997-01-01

    By using differential scanning calorimetry (DSC) energetic measurements associated with the different peaks displayed during linear heating of Cu-20% at. Mn were made, employing quenched and cold-worked materials. Unique to the situation observed in the quenched alloy in which disperse order is developed, in the deformed alloy such process is inhibited by the segregation of solute atoms to partial dislocations. An appropriate model for calculation the energy evolved during the pinning process was applied in order to determine the dislocation density from the exothermic peak designated as stage 4. The computed value, which is in excellent agreement with the one obtained from expressions governing the energy release accompanying recrystallization allows to verify together with microhardness measurements and kinetic analysis that the first observed thermal effect in the deformed materials effectively corresponds a solute segregation process. (Author) 35 refs

  7. Dipole strength distributions from HIGS Experiments

    Science.gov (United States)

    Werner, V.; Cooper, N.; Goddard, P. M.; Humby, P.; Ilieva, R. S.; Rusev, G.; Beller, J.; Bernards, C.; Crider, B. P.; Isaak, J.; Kelley, J. H.; Kwan, E.; Löher, B.; Peters, E. E.; Pietralla, N.; Romig, C.; Savran, D.; Scheck, M.; Tonchev, A. P.; Tornow, W.; Yates, S. W.; Zweidinger, M.

    2015-05-01

    A series of photon scattering experiments has been performed on the double-beta decay partners 76Ge and 76Se, in order to investigate their dipole response up to the neutron separation threshold. Gamma-ray beams from bremsstrahlung at the S-DALINAC and from Compton-backscattering at HIGS have been used to measure absolute cross sections and parities of dipole excited states, respectively. The HIGS data allows for indirect measurement of averaged branching ratios, which leads to significant corrections in the observed excitation cross sections. Results are compared to statistical calculations, to test photon strength functions and the Axel-Brink hypothesis

  8. Dipole vortices in the Great Australian Bight

    DEFF Research Database (Denmark)

    Cresswell, George R.; Lund-Hansen, Lars C.; Nielsen, Morten Holtegaard

    2015-01-01

    Shipboard measurements from late 2006 made by the Danish Galathea 3 Expedition and satellite sea surface temperature images revealed a chain of cool and warm mushroom' dipole vortices that mixed warm, salty, oxygen-poor waters on and near the continental shelf of the Great Australian Bight (GAB...... denser than the cooler offshore waters. The field of dipoles evolved and distorted, but appeared to drift westwards at 5km day-1 over two weeks, and one new mushroom carried GAB water southwards at 7km day(-1). Other features encountered between Cape Leeuwin and Tasmania included the Leeuwin Current...

  9. On the dipole approximation with error estimates

    Science.gov (United States)

    Boßmann, Lea; Grummt, Robert; Kolb, Martin

    2018-01-01

    The dipole approximation is employed to describe interactions between atoms and radiation. It essentially consists of neglecting the spatial variation of the external field over the atom. Heuristically, this is justified by arguing that the wavelength is considerably larger than the atomic length scale, which holds under usual experimental conditions. We prove the dipole approximation in the limit of infinite wavelengths compared to the atomic length scale and estimate the rate of convergence. Our results include N-body Coulomb potentials and experimentally relevant electromagnetic fields such as plane waves and laser pulses.

  10. Dipole strength distributions from HIGS Experiments

    Directory of Open Access Journals (Sweden)

    Werner V.

    2015-01-01

    76Ge and 76Se, in order to investigate their dipole response up to the neutron separation threshold. Gamma-ray beams from bremsstrahlung at the S-DALINAC and from Compton-backscattering at HIGS have been used to measure absolute cross sections and parities of dipole excited states, respectively. The HIGS data allows for indirect measurement of averaged branching ratios, which leads to significant corrections in the observed excitation cross sections. Results are compared to statistical calculations, to test photon strength functions and the Axel-Brink hypothesis

  11. Spectral structure of the pygmy dipole resonance.

    Science.gov (United States)

    Tonchev, A P; Hammond, S L; Kelley, J H; Kwan, E; Lenske, H; Rusev, G; Tornow, W; Tsoneva, N

    2010-02-19

    High-sensitivity studies of E1 and M1 transitions observed in the reaction 138Ba(gamma,gamma{'}) at energies below the one-neutron separation energy have been performed using the nearly monoenergetic and 100% linearly polarized photon beams of the HIgammaS facility. The electric dipole character of the so-called "pygmy" dipole resonance was experimentally verified for excitations from 4.0 to 8.6 MeV. The fine structure of the M1 "spin-flip" mode was observed for the first time in N=82 nuclei.

  12. Asymmetry of neoclassical transport by dipole electric field

    International Nuclear Information System (INIS)

    Wang Zhongtian; Wang Long

    2004-01-01

    Effects of dipole electric fields on neoclassical transport are studied. Large asymmetry in transport is created. The dipole fields, which are in a negative R-direction, reduce the ion drift, increase electron drift, and change the steps of excursion due to collisions. It is found that different levels of dipole field intensities have different types of transport. For the lowest level of the dipole field, the transport returns to the neoclassical one. For the highest level of the dipole field, the transport is turned to be the turbulence transport similar to the pseudo-classical transport. Experimental data may be corresponded to a large level of the dipole field intensity. (authors)

  13. Partial processing

    International Nuclear Information System (INIS)

    1978-11-01

    This discussion paper considers the possibility of applying to the recycle of plutonium in thermal reactors a particular method of partial processing based on the PUREX process but named CIVEX to emphasise the differences. The CIVEX process is based primarily on the retention of short-lived fission products. The paper suggests: (1) the recycle of fission products with uranium and plutonium in thermal reactor fuel would be technically feasible; (2) it would, however, take ten years or more to develop the CIVEX process to the point where it could be launched on a commercial scale; (3) since the majority of spent fuel to be reprocessed this century will have been in storage for ten years or more, the recycling of short-lived fission products with the U-Pu would not provide an effective means of making refabrication fuel ''inaccessible'' because the radioactivity associated with the fission products would have decayed. There would therefore be no advantage in partial processing

  14. Multiple transparency windows and Fano interferences induced by dipole-dipole couplings

    Science.gov (United States)

    Diniz, E. C.; Borges, H. S.; Villas-Boas, C. J.

    2018-04-01

    We investigate the optical properties of a two-level system (TLS) coupled to a one-dimensional array of N other TLSs with dipole-dipole coupling between the first neighbors. The first TLS is probed by a weak field, and we assume that it has a decay rate much greater than the decay rates of the other TLSs. For N =1 and in the limit of a Rabi frequency of a probe field much smaller than the dipole-dipole coupling, the optical response of the first TLS, i.e., its absorption and dispersion, is equivalent to that of a three-level atomic system in the configuration which allows one to observe the electromagnetically induced transparency (EIT) phenomenon. Thus, here we investigate an induced transparency phenomenon where the dipole-dipole coupling plays the same role as the control field in EIT in three-level atoms. We describe this physical phenomenon, named a dipole-induced transparency (DIT), and investigate how it scales with the number of coupled TLSs. In particular, we have shown that the number of TLSs coupled to the main TLS is exactly equal to the number of transparency windows. The ideas presented here are very general and can be implemented in different physical systems, such as an array of superconducting qubits, or an array of quantum dots, spin chains, optical lattices, etc.

  15. The electric dipole moment of the nucleon from simulations at imaginary vacuum angle theta

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, S. [RIKEN-BNL Research Center, Brookhaven National Laboratory, Upton (United States)]|[Tsukuba Univ. (Japan). Graduate School of Pure and Applied Sciences; Horsley, R.; Zanotti, J. [Edinburgh Univ. (United Kingdom). School of Physics; Izubuchi, T. [RIKEN-BNL Research Center, Brookhaven National Laboratory, Upton (United States)]|[Kanazawa Univ. (Japan). Inst. for Theoretical Physics; Nakamura, Y.; Pleiter, D.; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Division. Dept. of Mathematical Sciences

    2008-07-15

    We compute the electric dipole moment of proton and neutron from lattice QCD simulations with N{sub f}=2 flavors of dynamical quarks at imaginary vacuum angle {theta}. The calculation proceeds via the CP odd form factor F{sub 3}. A novel feature of our calculation is that we use partially twisted boundary conditions to extract F{sub 3} at zero momentum transfer. As a byproduct, we test the QCD vacuum at nonvanishing {theta}. (orig.)

  16. Partial gigantism

    Directory of Open Access Journals (Sweden)

    М.М. Karimova

    2017-05-01

    Full Text Available A girl with partial gigantism (the increased I and II fingers of the left foot is being examined. This condition is a rare and unresolved problem, as the definite reason of its development is not determined. Wait-and-see strategy is recommended, as well as correcting operations after closing of growth zones, and forming of data pool for generalization and development of schemes of drug and radial therapeutic methods.

  17. Contribution to the study of screw dislocations; Contribution a l'etude des dislocations helicoidales

    Energy Technology Data Exchange (ETDEWEB)

    Grilhe, J [Commissariat a l' Energie Atomique, Fontenay aux Roses (France). Centre d' Etudes Nucleaires

    1965-03-01

    The aim of this work is to study the germination, growth and properties of screw dislocations. In the introduction (first chapter), we describe briefly the main experimental results obtained by various authors (observations of screws by Amelinckx and Bontinck in ionic crystals, by Dash in silicon crystals and by Thomas and Whelan in aluminium based alloys). We then make a few considerations concerning characteristic geometry of screws and the various methods used for calculating the energy of a dislocation. In the second chapter we study the problems involving only slip of the screw around its cylinder. We calculate the equilibrium step as a function of the forces acting on the extremities. We determine the critical stress required to disrupt the screw and study the interactions between the screw and other dislocations of the lattice. In the third chapter we consider the problem of the stability when the dislocation can climb by absorption or emission of vacancies. We study separately the stability of the size which only involves volume diffusion and the stability of the shape which depends only on the rearrangement of the vacancies along the dislocation. In chapter four we put forward a germination model for the screws: since the vacancies are not absorbed by the screw dislocations, they form clusters which take up a spiral form. The formation of these spirals is studied from the geometrical point of view in face-centered cubic systems. In chapter five we make use of the results obtained in chapters two and three for studying the growth of the spirals. (author) [French] Le but de ce travail est d'etudier la germination, la croissance et les proprietes des dislocations helico ales. Dans l'introduction (premier chapitre), nous exposons brievement les principaux resultats experimentaux obtenus par differents auteurs (observations d'helice par Amelinckx et Bontinck dans les cristaux ioniques, par Dash dans des cristaux de silicium et par Thomas et Whelan dans des

  18. Mechanism of Strain Rate Effect Based on Dislocation Theory

    International Nuclear Information System (INIS)

    Kun, Qin; Shi-Sheng, Hu; Li-Ming, Yang

    2009-01-01

    Based on dislocation theory, we investigate the mechanism of strain rate effect. Strain rate effect and dislocation motion are bridged by Orowan's relationship, and the stress dependence of dislocation velocity is considered as the dynamics relationship of dislocation motion. The mechanism of strain rate effect is then investigated qualitatively by using these two relationships although the kinematics relationship of dislocation motion is absent due to complicated styles of dislocation motion. The process of strain rate effect is interpreted and some details of strain rate effect are adequately discussed. The present analyses agree with the existing experimental results. Based on the analyses, we propose that strain rate criteria rather than stress criteria should be satisfied when a metal is fully yielded at a given strain rate. (condensed matter: structure, mechanical and thermal properties)

  19. Riemann–Cartan Geometry of Nonlinear Dislocation Mechanics

    KAUST Repository

    Yavari, Arash

    2012-03-09

    We present a geometric theory of nonlinear solids with distributed dislocations. In this theory the material manifold-where the body is stress free-is a Weitzenböck manifold, that is, a manifold with a flat affine connection with torsion but vanishing non-metricity. Torsion of the material manifold is identified with the dislocation density tensor of nonlinear dislocation mechanics. Using Cartan\\'s moving frames we construct the material manifold for several examples of bodies with distributed dislocations. We also present non-trivial examples of zero-stress dislocation distributions. More importantly, in this geometric framework we are able to calculate the residual stress fields, assuming that the nonlinear elastic body is incompressible. We derive the governing equations of nonlinear dislocation mechanics covariantly using balance of energy and its covariance. © 2012 Springer-Verlag.

  20. Gradients of geometrically necessary dislocations from white beam microdiffraction

    International Nuclear Information System (INIS)

    Barabash, R.I.; Ice, G.E.; Pang, J.W.L.

    2005-01-01

    Variations in the local crystallographic orientation due to the presence of geometrically necessary dislocations and dislocation boundaries smear the distribution of intensity near Laue reflections. Here, some simple model distributions of geometrically necessary dislocations, GNDs, are used to estimate the dislocation tensor field from the intensity distribution of Laue peaks. Streaking of the Laue spots is found to be quantitatively and qualitatively distinct depending on the ratio between the absorption coefficient and the GND density gradient. In addition, different slip systems cause distinctly different Laue-pattern streaking. Experimental Laue patterns are therefore sensitive to stored dislocations and GNDs. As an example, white beam microdiffraction was applied to characterize the dislocation arrangement in a deformed polycrystalline Ni grain during in situ uniaxial tension

  1. Conceptual design of Dipole Research Experiment (DREX)

    Science.gov (United States)

    Xiao, Qingmei; Wang, Zhibin; Wang, Xiaogang; Xiao, Chijie; Yang, Xiaoyi; Zheng, Jinxing

    2017-03-01

    A new terrella-like device for laboratory simulation of inner magnetosphere plasmas, Dipole Research Experiment, is scheduled to be built at the Harbin Institute of Technology (HIT), China, as a major state scientific research facility for space physics studies. It is designed to provide a ground experimental platform to reproduce the inner magnetosphere to simulate the processes of trapping, acceleration, and transport of energetic charged particles restrained in a dipole magnetic field configuration. The scaling relation of hydromagnetism between the laboratory plasma of the device and the geomagnetosphere plasma is applied to resemble geospace processes in the Dipole Research Experiment plasma. Multiple plasma sources, different kinds of coils with specific functions, and advanced diagnostics are designed to be equipped in the facility for multi-functions. The motivation, design criteria for the Dipole Research Experiment experiments and the means applied to generate the plasma of desired parameters in the laboratory are also described. Supported by National Natural Science Foundation of China (Nos. 11505040, 11261140326 and 11405038), China Postdoctoral Science Foundation (Nos. 2016M591518, 2015M570283) and Project Supported by Natural Scientific Research Innovation Foundation in Harbin Institute of Technology (No. 2017008).

  2. Installation of the ALICE dipole magnet

    CERN Multimedia

    Maximilien Brice

    2005-01-01

    The large dipole magnet is installed on the ALICE detector at CERN. This magnet, which is cooled by demineralised water, will bend the path of muons that leave the huge rectangular solenoid (in the background). These muons are heavy electrons that interact less with matter, allowing them to traverse the main section of the detector.

  3. The isotopic dipole moment of HDO

    Energy Technology Data Exchange (ETDEWEB)

    Assafrao, Denise; Mohallem, Jose R [Laboratorio de Atomos e Moleculas Especiais, Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, CP 702, 30123-970, Belo Horizonte, MG (Brazil)

    2007-03-14

    An adiabatic variational approximation is used to study the monodeuterated water molecule, HDO, accounting for the isotopic effect. The isotopic dipole moment, pointing from D to H, is then calculated for the first time, yielding (1.5 {+-} 0.1) x 10{sup -3} Debye, being helpful in the interpretation of experiments. (fast track communication)

  4. LHC Dipoles: The countdown has begun

    CERN Document Server

    2002-01-01

    One of the LHC dipole magnets has just achieved a record magnetic field of 9 Tesla in one go without quenching. The challenge now is to increase the production rate to 35 magnets a month by 2004. As a new information panel in Building 30 shows, the countdown has begun.

  5. Forced flow cooling of ISABELLE dipole magnets

    International Nuclear Information System (INIS)

    Bamberger, J.A.; Aggus, J.; Brown, D.P.; Kassner, D.A.; Sondericker, J.H.; Strobridge, T.R.

    1976-01-01

    The superconducting magnets for ISABELLE will use a forced flow supercritical helium cooling system. In order to evaluate this cooling scheme, two individual dipole magnets were first tested in conventional dewars using pool boiling helium. These magnets were then modified for forced flow cooling and retested with the identical magnet coils. The first evaluation test used a l m-long ISA model dipole magnet whose pool boiling performance had been established. The same magnet was then retested with forced flow cooling, energizing it at various operating temperatures until quench occurred. The magnet performance with forced flow cooling was consistent with data from the previous pool boiling tests. The next step in the program was a full-scale ISABELLE dipole ring magnet, 4.25 m long, whose performance was first evaluated with pool boiling. For the forced flow test the magnet was shrunk-fit into an unsplit laminated core encased in a stainless steel cylinder. The high pressure gas is cooled below 4 K by a helium bath which is pumped below atmospheric pressure with an ejector nozzle. The performance of the full-scale dipole magnet in the new configuration with forced flow cooling, showed a 10 percent increase in the attainable maximum current as compared to the pool boiling data

  6. Dipole nano-laser: Theory and properties

    Energy Technology Data Exchange (ETDEWEB)

    Ghannam, T., E-mail: gtalal@hotmail.com [King Abdullah Institute for Nano-Technology, King Saud University, PO Box 2454, Riyadh 11451 (Saudi Arabia)

    2014-03-31

    In this paper we outline the main quantum properties of the system of nano-based laser called Dipole Nano-Laser emphasizing mainly on its ability to produce coherent light and for different configurations such as different embedding materials and subjecting it to an external classical electric field.

  7. Giant dipole resonances built on excited states

    International Nuclear Information System (INIS)

    Snover, K.A.

    1983-01-01

    The properties of giant dipole resonances built on excited nuclear states are reviewed, with emphasis on recent results. Nonstatistical (p,γ) reactions in light nuclei, and statistical complex-particle reactions in light and heavy nuclei are discussed. 27 references

  8. Formation of dipole vortex in the ionosphere

    International Nuclear Information System (INIS)

    Shukla, P.K.; Yu, M.Y.

    1985-01-01

    It is shown that isolated dipole vortices can exist in the F-region of the ionosphere. These are associated with the Rayleigh-Taylor and E x B 0 gradient drift instabilities. The vortices may be responsible for the rapid structuring of barium clouds as well as other phenomena observed in the upper ionosphere

  9. Fringing field measurement of dipole magnet

    International Nuclear Information System (INIS)

    Lu Hongyou; Jiang Weisheng; Mao Naifeng; Mao Xingwang

    1985-01-01

    The fringing field of a dipole magnet with a C-type circuit and homogeneous field in the gap has been measured including the distributions of fringing fields with and without magnetic shield. The measured data was analyzed by using the concept of virtual field boundary

  10. Scattering properties of point dipole interactions

    DEFF Research Database (Denmark)

    Zolotaryuk, Alexander; Christiansen, Peter Leth; Iermakova, S.V.

    2006-01-01

    dipole interactions with a renormalized coupling constant are analysed. Depending on the parameter values, all these interactions being self-adjoint extensions of the one-dimensional Schrodinger operator are shown to be divided into four types: (i) interactions will full transparency, (ii) non...

  11. Supersymmetric relations among electromagnetic dipole operators

    International Nuclear Information System (INIS)

    Graesser, Michael; Thomas, Scott

    2002-01-01

    Supersymmetric contributions to all leptonic electromagnetic dipole operators have essentially identical diagrammatic structure. With approximate slepton universality this allows the muon anomalous magnetic moment to be related to the electron electric dipole moment in terms of supersymmetric phases, and to radiative flavor changing lepton decays in terms of small violations of slepton universality. If the current discrepancy between the measured and standard model values of the muon anomalous magnetic moment is due to supersymmetry, the current bound on the electron electric dipole moment then implies that the phase of the electric dipole operator is less than 2x10 -3 . Likewise the current bound on μ→eγ decay implies that the fractional selectron-smuon mixing in the left-left mass squared matrix, δm μ-tildee-tilde) 2 /m l-tilde) 2 , is less than 10 -4 . These relations and constraints are fairly insensitive to details of the superpartner spectrum for moderate to large tan β

  12. Stability of the giant dipole resonance

    International Nuclear Information System (INIS)

    Espino, J.M.; Gallardo, M.

    1987-01-01

    The Giant Dipole Resonance (GDR), because of its stability and its typical period of vibration, can be used as a test for compound nucleus reactions at high temperatures. This stability is studied in a simple model up to 6 MeV of temperature. The experimental methods for getting the properties of the GDR at T ≠ 0 are also commented. (author)

  13. Results on Fermilab main injector dipole measurements

    International Nuclear Information System (INIS)

    Brown, B.C.; Baiod, R.; DiMarco, J.; Glass, H.D.; Harding, D.J.; Martin, P.S.; Mishra, S.; Mokhtarani, A.; Orris, D.F.; russell, O.A.; Tompkins, J.C.; Walbridge, D.G.C.

    1995-06-01

    Measurements of the Productions run of Fermilab Main Injector Dipole magnets is underway. Redundant strength measurements provide a set of data which one can fit to mechanical and magnetic properties of the assembly. Plots of the field contribution from the steel supplement the usual plots of transfer function (B/I) vs. I in providing insight into the measured results

  14. Electric dipole moment of 3He

    International Nuclear Information System (INIS)

    Avishai, Y.; Fabre de la Ripelle, M.

    1987-01-01

    The contribution of CP violating nucleon-nucleon interaction to the electric dipole moment of 3 He is evaluated following a recent proposal for its experimental detection. Two models of CP violating interactions are used, namely, the Kobayashi-Maskawa mechanism and the occurrence of the Θ term in the QCD lagrangian. These CP violating interactions are combined with realistic strong nucleon-nucleon interactions to induce a CP forbidden component of the 3 He wave function. The matrix element of the electric dipole operator is then evaluated between CP allowed and CP forbidden components yielding the observable electric dipole moment. Using the parameters emerging from the penguin terms in the Kobaysashi-Maskawa model we obtain a result much larger than the electric dipole moment of the neutron in the same model. On the other hand, no enhancement is found for the Θ-term mechanism. A possible explanation for this difference is discussed. Numerical estimates can be given only in the Kobayashi-Maskawa model, giving d( 3 He) ≅ 10 30 e . cm. In the second mechanism, the estimate give d ( 3 He) ≅ 10 16 anti Θ. (orig.)

  15. Induced electric dipole in a quantum ring

    Energy Technology Data Exchange (ETDEWEB)

    Dantas, L.; Furtado, Claudio, E-mail: furtado@fisica.ufpb.br

    2013-12-02

    In this contribution, we investigate the quantum dynamics of a neutral particle confined in a quantum ring potential. We use two different field configurations for induced electric dipole in the presence of electric and magnetic fields and a general confining potential, for which we solve the Schrödinger equation and obtain the complete set of eigenfunctions and eigenvalues.

  16. Search for a neutron electric dipole moment

    Energy Technology Data Exchange (ETDEWEB)

    Morse, J [Rutherford Appleton Laboratory, Chilton (U.K.)

    1984-03-01

    To search for evidence of a breakdown of symmetry under the time reversal transformation, a magnetic resonance measurement is made to detect an electric dipole moment (EDM) of ultracold neutrons stored for periods approximately= 60s in the presence of a strong electric field. The measured neutron EDM is (0.3 +- 4.8) x 10/sup -25/ ecm.

  17. Jaw Dislocation as an Unusual Complication of Upper Endoscopy

    Directory of Open Access Journals (Sweden)

    Evan S. Dellon

    2016-05-01

    Full Text Available This case report presents an unusual complication of upper endoscopy, resulting in jaw dislocation. Temporomandibular joint dislocation is commonly reported in association with anesthesia and intubation, but it is not widely recognized as a complication of gastrointestinal endoscopy. This report also reviews the current literature regarding this complication and discusses the potential causes of dislocation, differential diagnoses for jaw pain following endoscopy, and recommendations for prevention.

  18. Ionization of Rb Rydberg atoms in the attractive nsnp dipole-dipole potential

    International Nuclear Information System (INIS)

    Park, Hyunwook; Shuman, E. S.; Gallagher, T. F.

    2011-01-01

    We have observed the ionization of a cold gas of Rb Rydberg atoms which occurs when nsns van der Waals pairs of ns atoms of n≅ 40 on a weakly repulsive potential are transferred to an attractive dipole-dipole nsnp potential by a microwave transition. Comparing the measurements to a simple model shows that the initial 300-μK thermal velocity of the atoms plays an important role. Excitation to a repulsive dipole-dipole potential does not lead to more ionization on a 15-μs time scale than leaving the atoms in the weakly repulsive nsns state. This observation is slightly surprising since a radiative transition must occur to allow ionization in the latter case. Finally, by power broadening of the microwave transition, to allow transitions from the initial nsns state to the nsnp state over a broad range of internuclear spacings, it is possible to accelerate markedly the evolution to a plasma.

  19. Dual Aharonov-Casher effect and persistent dipole current

    International Nuclear Information System (INIS)

    Yi, J.; Jeon, G.S.; Choi, M.Y.

    1995-01-01

    An electric dipole moving in a magnetic field acquires a nontrivial quantum phase in the appropriate configuration. It is shown that this phase is manifested by the persistent dipole current induced on a ring pierced by a line of magnetic monopoles. Such a current depends on the statistics of the dipoles, which may have interesting implications for experiments. It is also pointed out that the dipole current cannot be self-sustained

  20. Position and Momentum Entanglement of Dipole-Dipole Interacting Atoms in Optical Lattices

    Science.gov (United States)

    Opatrný, T.; Kolář, M.; Kurizki, G.

    We consider a possible realization of the position- and momentum-correlated atomic pairs that are confined to adjacent sites of two mutually shifted optical lattices and are entangled via laser-induced dipole-dipole interactions. The Einstein-Podolsky-Rosen (EPR) "paradox" [Einstein 1935] with translational variables is then modified by lattice-diffraction effects. We study a possible mechanism of creating such diatom entangled states by varying the effective mass of the atoms.

  1. Translational Entanglement of Dipole-Dipole Interacting Atoms in Optical Lattices

    OpenAIRE

    Opatrny, T.; Deb, B.; Kurizki, G.

    2003-01-01

    We propose and investigate a realization of the position- and momentum-correlated Einstein-Podolsky-Rosen (EPR) states [Phys. Rev. 47, 777 (1935)] that have hitherto eluded detection. The realization involves atom pairs that are confined to adjacent sites of two mutually shifted optical lattices and are entangled via laser-induced dipole-dipole interactions. The EPR "paradox" with translational variables is then modified by lattice-diffraction effects, and can be verified to a high degree of ...

  2. Pair Interaction of Dislocations in Two-Dimensional Crystals

    Science.gov (United States)

    Eisenmann, C.; Gasser, U.; Keim, P.; Maret, G.; von Grünberg, H. H.

    2005-10-01

    The pair interaction between crystal dislocations is systematically explored by analyzing particle trajectories of two-dimensional colloidal crystals measured by video microscopy. The resulting pair energies are compared to Monte Carlo data and to predictions derived from the standard Hamiltonian of the elastic theory of dislocations. Good agreement is found with respect to the distance and temperature dependence of the interaction potential, but not regarding the angle dependence where discrete lattice effects become important. Our results on the whole confirm that the dislocation Hamiltonian allows a quantitative understanding of the formation and interaction energies of dislocations in two-dimensional crystals.

  3. Fabrication of mesoscopic floating Si wires by introducing dislocations

    International Nuclear Information System (INIS)

    Motohashi, Mitsuya; Shimizu, Kazuya; Niwa, Masaaki; Suzuki, Toshiaki

    2014-01-01

    We fabricated a mesoscopic Si wire by introducing dislocations in a silicon wafer before HF anodization. The dislocations formed along the (111) crystal plane. The outline of the dislocation line was an inverted triangle. The resulting wire floated on a bridge girder and had a hybrid structure consisting of a porous layer and crystalline Si. The cross section of the wire had an inverted triangle shape. The wire formation mechanism is discussed in terms of carrier transport, crystal structure, and dislocation formation during anodization. (paper)

  4. Fabrication of mesoscopic floating Si wires by introducing dislocations

    Science.gov (United States)

    Motohashi, Mitsuya; Shimizu, Kazuya; Suzuki, Toshiaki; Niwa, Masaaki

    2014-12-01

    We fabricated a mesoscopic Si wire by introducing dislocations in a silicon wafer before HF anodization. The dislocations formed along the (111) crystal plane. The outline of the dislocation line was an inverted triangle. The resulting wire floated on a bridge girder and had a hybrid structure consisting of a porous layer and crystalline Si. The cross section of the wire had an inverted triangle shape. The wire formation mechanism is discussed in terms of carrier transport, crystal structure, and dislocation formation during anodization.

  5. Traumatic Anterior Dislocation of Hip in a Child- Case Report

    Directory of Open Access Journals (Sweden)

    S Ahmad

    2015-03-01

    Full Text Available Traumatic hip dislocation in children is relatively rare accounting for about 5% of all hip dislocations. Most of the hip dislocations seen in children are of the posterior type but the much rarer anterior and anterior-inferior (obturator types have also been described. We present the case of an eight years old girl with an obturator type of hip dislocation following trivial trauma. She was treated with closed reduction and immobilisation in skin traction for three weeks. She was followed up closely for one year and did not develop any complications during that period.

  6. Dislocation kinetics and the acoustic-wave approximation for liquids

    International Nuclear Information System (INIS)

    Stout, R.B.

    1983-03-01

    A dislocation-dependent model for liquids describes the lattice deformation and the fluidity deformation as additive deformations. The lattice deformation represents distortions of an atom's potential energy structure and is a recoverable deformation response. The fluidity deformation represents discontinuous repositioning of atoms by dislocation kinetics in the lattice structure and is a nonrecoverable deformation response. From this model, one concludes that in liquids the acoustic-wave approximation is a description of a recoverable oscillation deformation that has dissipation because of dislocation kinetics. Other more-complex waves may exist, but such waves would rapidly disappear because of the small thermodynamic potential for dislocation kinetics in liquids

  7. [New varieties of lateral metatarsophalangeal dislocations of the great toe].

    Science.gov (United States)

    Bousselmame, N; Rachid, K; Lazrak, K; Galuia, F; Taobane, H; Moulay, I

    2001-04-01

    We report seven cases of traumatic dislocation of the great toe, detailing the anatomy, the mechanism of injury and the radiographic diagnosis. We propose an additional classification based on three hereto unreported cases. Between october 1994 and october 1997, we treated seven patients with traumatic dislocation of the first metatarso-phalangeal joint of the great toe. There were six men and one woman, mean age 35 years (range 24 - 44 years). Dislocation was caused by motor vehicle accidents in four cases and by falls in three. Diagnosis was made on anteroposterior, lateral and medial oblique radiographs. According to Jahss' classification, there was one type I and three type IIB dislocations. There was also one open lateral dislocation and two dorsomedial dislocations. Only these dorsomedial dislocations required open reduction, done via a dorsal approach. Mean follow-up was 17.5 months (range 9 - 24 months) in six cases. One patient was lost to follow-up. The outcome was good in six cases and poor in one (dorsomedial dislocation). Dislocation of the first metatarso-phalangeal joint of the great toe is an uncommon injury. In 1980, Jahss reported two cases and reviewed three others described in the literature. He proposed three types of dislocation based on the feasibility of closed reduction (type I, II and IIB). In 1991, Copeland and Kanat reported a unique case in which there was an association of IIA and IIB lesions. They proposed an addition to the classification (type IIC). In 1994, Garcia Mata et al. reported another case which had not been described by Jahss and proposed another addition. All dislocations reported to date have been sagittal dislocations. Pathological alteration of the collateral ligaments has not been previously reported. In our experience, we have seen one case of open lateral dislocation due, at surgical exploration, to medial ligament rupture and two cases of dorsomedial dislocation due, at surgical exploration, to lateral ligament

  8. Dislocation Structures in Creep-deformed Polycrystalline MgO

    DEFF Research Database (Denmark)

    Bilde-Sørensen, Jørgen

    1972-01-01

    dislocation segments lie in their slip or climb planes. On the basis of this structure, a model is proposed in which glide is the principal cause of deformation but the rate-limiting process, i.e. annealing of the network, is diffusion-controlled. Theoretical estimates and experimental results agree within 1...... energy of 76 ± 12 kcal/mol. The creep rate is independent of grain size. The dislocation structure was investigated by transmission electron microscopy. The total dislocation density follows the relation, σ=bG√ρ, commonly found for metals. The dislocations form a 3-dimensional network in which many...

  9. Temporomandibular joint dislocation due to acute propranolol intoxication

    Directory of Open Access Journals (Sweden)

    Abbas Aghabiklooei

    2010-07-01

    Full Text Available Abbas Aghabiklooei1, Homan Elahi2, Babak Mostafazadeh31Department of Medical Toxicology and Forensic Medicine, Iran University of Medical Sciences, Tehran, Iran; 2Firouzgar Hospital, Department of ENT, Tehran, Iran; 3Department of Medical Toxicology and Forensic Medicine, Shaheed Beheshty University of Medical Sciences, Tehran, IranAbstract: Temporomandibular joint (TMJ dislocation has not previously been reported as a complication of beta-blocker toxicity. We are reporting two cases of TMJ dislocation resulted from acute severe intoxication with pure propranolol (PPL for the first time. Bilateral TMJ dislocation happened in two patients who were admitted to intensive care unit with diagnosis of severe acute PPL toxicity. Clinical diagnosis of TMJ dislocation was obtained by physical examination. Successful reduction was performed for both patients without subsequent recurrence in two weeks following hospital discharge. Both of our subjects had no previous history of lower jaw dislocation. There was not any risk factor for dislocation such as convulsion during admission period, recent face trauma, or oral manipulation by the medical team. This study showed that TMJ dislocation may occur after severe acute PPL toxicity probably due to spastic contraction of the lateral pterygoid muscle. This is against previously mentioned hypothesis that stated masseteric muscles contraction as the main cause of a bilateral dislocated TMJ.Keywords: propranolol, toxicity, temporomandibular joint dislocation

  10. Bending energy of buckled edge dislocations

    Science.gov (United States)

    Kupferman, Raz

    2017-12-01

    The study of elastic membranes carrying topological defects has a longstanding history, going back at least to the 1950s. When allowed to buckle in three-dimensional space, membranes with defects can totally relieve their in-plane strain, remaining with a bending energy, whose rigidity modulus is small compared to the stretching modulus. In this paper we study membranes with a single edge dislocation. We prove that the minimum bending energy associated with strain-free configurations diverges logarithmically with the size of the system.

  11. Optimal control of orientation and entanglement for two dipole-dipole coupled quantum planar rotors.

    Science.gov (United States)

    Yu, Hongling; Ho, Tak-San; Rabitz, Herschel

    2018-05-09

    Optimal control simulations are performed for orientation and entanglement of two dipole-dipole coupled identical quantum rotors. The rotors at various fixed separations lie on a model non-interacting plane with an applied control field. It is shown that optimal control of orientation or entanglement represents two contrasting control scenarios. In particular, the maximally oriented state (MOS) of the two rotors has a zero entanglement entropy and is readily attainable at all rotor separations. Whereas, the contrasting maximally entangled state (MES) has a zero orientation expectation value and is most conveniently attainable at small separations where the dipole-dipole coupling is strong. It is demonstrated that the peak orientation expectation value attained by the MOS at large separations exhibits a long time revival pattern due to the small energy splittings arising form the extremely weak dipole-dipole coupling between the degenerate product states of the two free rotors. Moreover, it is found that the peak entanglement entropy value attained by the MES remains largely unchanged as the two rotors are transported to large separations after turning off the control field. Finally, optimal control simulations of transition dynamics between the MOS and the MES reveal the intricate interplay between orientation and entanglement.

  12. Formation and temporal evolution of the Lamb-dipole

    DEFF Research Database (Denmark)

    Nielsen, A.H.; Juul Rasmussen, J.

    1997-01-01

    of the evolving dipoles depend on the initial condition. However, the gross properties of their evolution are only weakly dependent on the detailed structure and can be well-described by the so-called Lamb-dipole solution. The viscous decay of the Lamb-dipole, leading to an expansion and a decreasing velocity...

  13. Dislocation structure and cold resistance of low-carbon steel

    International Nuclear Information System (INIS)

    Gul', Yu.P.; Karnaukh, A.I.

    1975-01-01

    In the formation of the dislocation structure of a small (10%) deformation, the determining effect on the cold brittleness temperature is exerted by the degree of uniformity in the distribution of dislocations and microvolumes. The overall density of the dislocations is of secondary importance here. By pretreatment to achieve more uniform distribution and dispersion of particles of the excess phase, the degree of uniformity of dislocation distribution in microvolumes can be increased, the cold brittleness temperature lowered and the effect of various deformation patterns on resistance to cold counterbalanced. The formation of a cell-type dislocation structure in the case of a nonuniform distribution of relatively large particles of the excess phase and in that of a large overall density of dislocations does not result in low brittleness temperatures. The formation of a cell-type dislocation structure in the case of uniform distribution of particles of the excess phase and of a comparatively small overall density of dislocations is accompanied by a very pronounced decrease in cold brittleness temperature not only by comparison with other types of dislocation structure but also with the normalized state. At the same time the formation of this kind of a cell structure leads to a substantial (factor of 2-5) increase in resistance to plastic deformation. The prerequisites for obtaining an optimum dislocation are fulfilled either by a combination of hardening from the austenitic region and prompt, small-scale (5%) deformation, or by a combination of accelerated cooling from the austenitic region, 30-40% deformation and high yield. The size of the dislocation cells observed under the electron microscope does not exhibit - within the limits investigated - any direct effect on the cold brittleness temperature. (author)

  14. Dipole-dipole interactions in a hot atomic vapor and in an ultracold gas of Rydberg atoms

    Science.gov (United States)

    Sautenkov, V. A.; Saakyan, S. A.; Bronin, S. Ya; Klyarfeld, A. B.; Zelener, B. B.; Zelener, B. V.

    2018-01-01

    In our paper ideal and non-ideal gas media of neutral atoms are analyzed. The first we discuss a dipole broadening of atomic transitions in excited dilute and dense metal vapors. Then the theoretical studies of the dipole-dipole interactions in dense ultracold gas of Rydberg atoms are considered. Possible future experiments on a base of our experimental arrangement are suggested.

  15. The patellofemoral joint: from dysplasia to dislocation

    Science.gov (United States)

    Zaffagnini, Stefano; Grassi, Alberto; Zocco, Gianluca; Rosa, Michele Attilo; Signorelli, Cecilia; Muccioli, Giulio Maria Marcheggiani

    2017-01-01

    Patellofemoral dysplasia is a major predisposing factor for instability of the patellofemoral joint. However, there is no consensus as to whether patellofemoral dysplasia is genetic in origin, caused by imbalanced forces producing maltracking and remodelling of the trochlea during infancy and growth, or due to other unknown and unexplored factors. The biomechanical effects of patellofemoral dysplasia on patellar stability and on surgical procedures have not been fully investigated. Also, different anatomical and demographic risk factors have been suggested, in an attempt to identify the recurrent dislocators. Therefore, a comprehensive evaluation of all the radiographic, MRI and CT parameters can help the clinician to assess patients with primary and recurrent patellar dislocation and guide management. Patellofemoral dysplasia still represents an extremely challenging condition to manage. Its controversial aetiology and its complex biomechanical behaviour continue to pose more questions than answers to the research community, which reflects the lack of universally accepted guidelines for the correct treatment. However, due to the complexity of this condition, an extremely personalised approach should be reserved for each patient, in considering and addressing the anatomical abnormalities responsible for the symptoms. Cite this article: EFORT Open Rev 2017;2. DOI: 10.1302/2058-5241.2.160081. Originally published online at www.efortopenreviews.org PMID:28630757

  16. Uranium and thorium migration under dislocative metamorphism

    International Nuclear Information System (INIS)

    Titov, V.K.; Bilibina, T.V.; Dashkova, A.D.; Il'in, V.K.; Makarova, L.I.; Shmuraeva, L.Ya.

    1978-01-01

    Investigated were peculiarities of uranium and thorium behaviour in the process of dislocation metamorphism on the basis of regional fracture zones of early-proterozoic embedding of Ukrainian, Aldan and Baltic shields. The studied zones correspond to tectonite of green-shale and almandin-amphibolite facies of regional metamorphism according to mineral associations. The most peculiar feature of the tectonites of green-shale facies is uranium presence in migrationally able forms, which can be involved afterwards into the ore process by hydrothermal solutions. Adsorved forms of uranium on the crystal surface or separate grains and in the cracks, as well as microinclusions of uranium minerals, selectively timed to mineral structure defects prevail among easily mobile uranium compounds. Dissolved uranium is present, evidently in gas-liquid inclusions in minerals and pore waters. There forms of uranium presence are peculiar for epidote-chlorite mylonites, as well as cataclasites and diaphthorites related to them by blastomylonites of almandin-amphibolite facies. Wide range of manifestation of this process, caused by multikilometer extension of deep fracture zones permit to consider the formations of green-shale facies of dislocation metamorphism as one of the main uranium sources in deposit formation in different uranium-ore associations different age

  17. Slip patterns and preferred dislocation boundary planes

    DEFF Research Database (Denmark)

    Winther, G.

    2003-01-01

    The planes of deformation induced extended planar dislocation boundaries are analysed in two different co-ordinate systems, namely the macroscopic system defined by the deformation axes and the crystallographic system given by the crystallographic lattice. The analysis covers single and polycryst......The planes of deformation induced extended planar dislocation boundaries are analysed in two different co-ordinate systems, namely the macroscopic system defined by the deformation axes and the crystallographic system given by the crystallographic lattice. The analysis covers single...... and polycrystals of fcc metals in three deformation modes (rolling, tension and torsion). In the macroscopic system, boundaries lie close to the macroscopically most stressed planes. In the crystallographic system, the boundary plane depends on the grain/crystal orientation. The boundary planes in both co......-ordinate systems are rationalised based on the slip. The more the slip is concentrated on a slip plane, the closer the boundaries lie to this. The macroscopic preference arises from the macroscopic directionality of the slip. The established relations are applied to (a) prediction of boundary planes from slip...

  18. Field of a dipole in charged black-hole electrostatics

    International Nuclear Information System (INIS)

    Souza, J.A.

    1979-01-01

    By using the solution of Adler and Das for Maxwell's equations in a Reissner-Nordstroem optimally charged background metric, the field of a static electric dipole is found and then, by a duality rotation, the field of a static magnetic dipole is obtained. A generalization of the concept of electric-dipole moment is proposed for static dipoles in curved manifolds, and the behaviour of the fields both for the dipole very near and very far from the singular surface of the Reissner-Nordstroem geometry is studied. (author)

  19. Basal and prism dislocation cores in magnesium: comparison of first-principles and embedded-atom-potential methods predictions

    International Nuclear Information System (INIS)

    Yasi, J A; Nogaret, T; Curtin, W A; Trinkle, D R; Qi, Y; Hector, L G Jr

    2009-01-01

    The core structures of screw and edge dislocations on the basal and prism planes in Mg, and the associated gamma surfaces, were studied using an ab initio method and the embedded-atom-method interatomic potentials developed by Sun et al and Liu et al. The ab initio calculations predict that the basal plane dislocations dissociate into partials split by 16.7 Å (edge) and 6.3 Å (screw), as compared with 14.3 Å and 12.7 Å (Sun and Liu edge), and 6.3 Å and 1.4 Å (Sun and Liu screw), with the Liu screw dislocation being metastable. In the prism plane, the screw and edge cores are compact and the edge core structures are all similar, while ab initio does not predict a stable prismatic screw in stress-free conditions. These results are qualitatively understood through an examination of the gamma surfaces for interplanar sliding on the basal and prism planes. The Peierls stresses at T = 0 K for basal slip are a few megapascals for the Sun potential, in agreement with experiments, but are ten times larger for the Liu potential. The Peierls stresses for prism slip are 10–40 MPa for both potentials. Overall, the dislocation core structures from ab initio are well represented by the Sun potential in all cases while the Liu potential shows some notable differences. These results suggest that the Sun potential is preferable for studying other dislocations in Mg, particularly the (c + a) dislocations, for which the core structures are much larger and not accessible by ab initio methods

  20. Partial avascular necrosis after talar neck fracture.

    Science.gov (United States)

    Babu, Nina; Schuberth, John M

    2010-09-01

    Recently, it has been shown that avascular necrosis of the talus can occur in only a portion of the talar body. There is little information regarding the geographic location of the avascular segment and the clinical significance of an incomplete avascular process. Seven patients with partial avascular necrosis after Hawkins type II or III fracture dislocations were evaluated with magnetic resonance scans. The precise anatomic location of the avascular segment was determined and assigned to a specific quadrant of the talar body. The operative exposure, incidence of collapse, and time to operative intervention was recorded. The avascular segment of the talar body was located predominantly in the anterior lateral and superior portion in six of the seven patients. Collapse occurred in three of the patients in the area of avascular process. There were no observable trends with regard to operative exposure, Hawkins classification, incidence of collapse, or time to operative intervention to the location of the avascular segment. Partial avascular necrosis can occur after fracture dislocation of the talus. The predominant location of the avascular segment was the anterior lateral and superior portion of the talar body. This observation corresponds to regional damage to the blood supply of the talus and may help clarify the pathogenesis of partial avascular process.

  1. Projected Dipole Model for Quantum Plasmonics

    DEFF Research Database (Denmark)

    Yan, Wei; Wubs, Martijn; Mortensen, N. Asger

    2015-01-01

    of classical electrodynamics, while quantum properties are described accurately through an infinitely thin layer of dipoles oriented normally to the metal surface. The nonlocal polarizability of the dipole layer-the only introduced parameter-is mapped from the free-electron distribution near the metal surface...... as obtained with 1D quantum calculations, such as time-dependent density-functional theory (TDDFT), and is determined once and for all. The model can be applied in two and three dimensions to any system size that is tractable within classical electrodynamics, while capturing quantum plasmonic aspects......Quantum effects of plasmonic phenomena have been explored through ab initio studies, but only for exceedingly small metallic nanostructures, leaving most experimentally relevant structures too large to handle. We propose instead an effective description with the computationally appealing features...

  2. The LHC dipole test control architecture

    International Nuclear Information System (INIS)

    Gorskaya, E.; Samojlov, V.; Raimondo, A.; Rijllart, A.

    2003-01-01

    The next large accelerator project at CERN is the Large Hadron Collider, which is foreseen to be installed in the existing LEP tunnel, and scheduled to be commissioned in 2007. For this project, 1200 15-metre long dipole magnets need to be tested at CERN in warm and cold conditions on dedicated test benches that are under development. The final LHC dipole series test set-up will consist of 12 benches organized in 6 clusters of two benches sharing the largest and most expensive devices. This sharing is made possible by a deliberate de-phasing of the tests among magnets, ensuring an optimum use of resources, such as cryogenics and power equipment, without limiting the total throughput. An offered two-level control architecture includes: 1) the Test 'Master' that drives the test for a cluster; 2) the Resource 'Manager' that allocates common devices and central resources. The implementation of this architecture is done in the LabVIEW environment

  3. Broadband standard dipole antenna for antenna calibration

    Science.gov (United States)

    Koike, Kunimasa; Sugiura, Akira; Morikawa, Takao

    1995-06-01

    Antenna calibration of EMI antennas is mostly performed by the standard antenna method at an open-field test site using a specially designed dipole antenna as a reference. In order to develop broadband standard antennas, the antenna factors of shortened dipples are theoretically investigated. First, the effects of the dipole length are analyzed using the induced emf method. Then, baluns and loads are examined to determine their influence on the antenna factors. It is found that transformer-type baluns are very effective for improving the height dependence of the antenna factors. Resistive loads are also useful for flattening the frequency dependence. Based on these studies, a specification is developed for a broadband standard antenna operating in the 30 to 150 MHz frequency range.

  4. Electric Dipole Moment Results from lattice QCD

    Science.gov (United States)

    Dragos, Jack; Luu, Thomas; Shindler, Andrea; de Vries, Jordy

    2018-03-01

    We utilize the gradient flow to define and calculate electric dipole moments induced by the strong QCD θ-term and the dimension-6 Weinberg operator. The gradient flow is a promising tool to simplify the renormalization pattern of local operators. The results of the nucleon electric dipole moments are calculated on PACS-CS gauge fields (available from the ILDG) using Nf = 2+1, of discrete size 323×64 and spacing a ≃ 0.09 fm. These gauge fields use a renormalization-group improved gauge action and a nonperturbatively O(a) improved clover quark action at β = 1.90, with cSW = 1.715. The calculation is performed at pion masses of mπ ≃ 411, 701 MeV.

  5. Electric Dipole Moment Results from lattice QCD

    Directory of Open Access Journals (Sweden)

    Dragos Jack

    2018-01-01

    Full Text Available We utilize the gradient flow to define and calculate electric dipole moments induced by the strong QCD θ-term and the dimension-6 Weinberg operator. The gradient flow is a promising tool to simplify the renormalization pattern of local operators. The results of the nucleon electric dipole moments are calculated on PACS-CS gauge fields (available from the ILDG using Nf = 2+1, of discrete size 323×64 and spacing a ≃ 0.09 fm. These gauge fields use a renormalization-group improved gauge action and a nonperturbatively O(a improved clover quark action at β = 1.90, with cSW = 1.715. The calculation is performed at pion masses of mπ ≃ 411, 701 MeV.

  6. Energy flow of electric dipole radiation in between parallel mirrors

    Science.gov (United States)

    Xu, Zhangjin; Arnoldus, Henk F.

    2017-11-01

    We have studied the energy flow patterns of the radiation emitted by an electric dipole located in between parallel mirrors. It appears that the field lines of the Poynting vector (the flow lines of energy) can have very intricate structures, including many singularities and vortices. The flow line patterns depend on the distance between the mirrors, the distance of the dipole to one of the mirrors and the angle of oscillation of the dipole moment with respect to the normal of the mirror surfaces. Already for the simplest case of a dipole moment oscillating perpendicular to the mirrors, singularities appear at regular intervals along the direction of propagation (parallel to the mirrors). For a parallel dipole, vortices appear in the neighbourhood of the dipole. For a dipole oscillating under a finite angle with the surface normal, the radiating tends to swirl around the dipole before travelling off parallel to the mirrors. For relatively large mirror separations, vortices appear in the pattern. When the dipole is off-centred with respect to the midway point between the mirrors, the flow line structure becomes even more complicated, with numerous vortices in the pattern, and tiny loops near the dipole. We have also investigated the locations of the vortices and singularities, and these can be found without any specific knowledge about the flow lines. This provides an independent means of studying the propagation of dipole radiation between mirrors.

  7. Perineal anterior dislocation of the hip with avulsion fracture of ...

    African Journals Online (AJOL)

    Traumatic anterior dislocation of the hip is rare even in children. Very uncommon also is the perineal variant of the inferior type of anterior dislocation with concomitant avulsion fracture of the greater trochanter. We report such a case highlighting the peculiarity of its management. No similar case of triumvirate injury of the hip ...

  8. Management of neglected traumatic posterior dislocations of the hip ...

    African Journals Online (AJOL)

    Within a period of six months, three men were admitted following falls which had occurred more than one week previously. They had all sustained minor trauma but directly after the injury they were unable to bear weight on the affected limb. All three had Grade 1 posterior dislocations of the hip. Although the dislocation had ...

  9. Thermal activation of dislocations in large scale obstacle bypass

    Science.gov (United States)

    Sobie, Cameron; Capolungo, Laurent; McDowell, David L.; Martinez, Enrique

    2017-08-01

    Dislocation dynamics simulations have been used extensively to predict hardening caused by dislocation-obstacle interactions, including irradiation defect hardening in the athermal case. Incorporating the role of thermal energy on these interactions is possible with a framework provided by harmonic transition state theory (HTST) enabling direct access to thermally activated reaction rates using the Arrhenius equation, including rates of dislocation-obstacle bypass processes. Moving beyond unit dislocation-defect reactions to a representative environment containing a large number of defects requires coarse-graining the activation energy barriers of a population of obstacles into an effective energy barrier that accurately represents the large scale collective process. The work presented here investigates the relationship between unit dislocation-defect bypass processes and the distribution of activation energy barriers calculated for ensemble bypass processes. A significant difference between these cases is observed, which is attributed to the inherent cooperative nature of dislocation bypass processes. In addition to the dislocation-defect interaction, the morphology of the dislocation segments pinned to the defects play an important role on the activation energies for bypass. A phenomenological model for activation energy stress dependence is shown to describe well the effect of a distribution of activation energies, and a probabilistic activation energy model incorporating the stress distribution in a material is presented.

  10. Proximal tibiofibular dislocation: a case report and review of literature

    NARCIS (Netherlands)

    Nieuwe Weme, R. A.; Somford, M. P.; Schepers, T.

    2014-01-01

    An isolated dislocation of the proximal tibiofibular joint is uncommon. The mechanism of this injury is usually sports related. We present a case where initial X-rays did not show the tibiofibular joint dislocation conclusively. It was diagnosed after comparative bilateral AP X-rays of the knees

  11. Rows of Dislocation Loops in Aluminium Irradiated by Aluminium Ions

    DEFF Research Database (Denmark)

    Henriksen, L.; Johansen, A.; Koch, J.

    1967-01-01

    Single-crystal aluminium specimens, irradiated with 50-keV aluminium ions, contain dislocation loops that are arranged in regular rows along <110 > directions. ©1967 The American Institute of Physics......Single-crystal aluminium specimens, irradiated with 50-keV aluminium ions, contain dislocation loops that are arranged in regular rows along directions. ©1967 The American Institute of Physics...

  12. Superior dislocation hip with anterior column acetabular fracture ...

    African Journals Online (AJOL)

    Superior variety of anterior dislocation of the hip is a rare injury. Its occurrence with acetabular fractures has been documented infrequently. We report a case of superior dislocation of the hip with anterior column acetabular fracture. Open reduction of the hip and internal fixation of the fracture was carried out using a twin ...

  13. Irradiation-induced amorphization in split-dislocation cores

    International Nuclear Information System (INIS)

    Ovid'ko, I.A.; Rejzis, A.B.

    1999-01-01

    The model describing special splitting of lattice and grain-boundary dislocations as one of the micromechanisms of solid-phase amorphization in irradiated crystals is proposed. Calculation of energy characteristics of the process of dislocations special splitting is carried out [ru

  14. Ab initio simulation of dislocation cores in metals

    International Nuclear Information System (INIS)

    Ventelon, L.

    2008-01-01

    In the framework of the multi scale simulation of metals and alloys plasticity, the aim of this study is to develop a methodology of ab initio dislocations study and to apply it to the [111] screw dislocation in the bc iron. (A.L.B.)

  15. Dislocation multiplication rate in the early stage of germanium plasticity

    Czech Academy of Sciences Publication Activity Database

    Fikar, J.; Dupas, Corinne; Kruml, Tomáš; Jacques, A.; Martin, J. L.

    400-401, - (2005), s. 431-434 ISSN 0921-5093. [Dislocations 2004. La Colle-sur-Loup, 13.09.2004-17.09.2004] Institutional research plan: CEZ:AV0Z2041904 Keywords : dislocation multiplication * germanium * constitutive modelling Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.347, year: 2005

  16. Bilateral Posterior Tibial Tendon and Flexor Digitorum Longus Dislocations.

    Science.gov (United States)

    Padegimas, Eric M; Beck, David M; Pedowitz, David I

    2017-04-01

    The authors present a case of a previously healthy and athletic 17-year-old female who presented with a 3.5-year history of medial left ankle pain after sustaining an inversion injury while playing basketball. Prior to presentation, she had failed prior immobilization and physical therapy for a presumed ankles sprain. Physical examination revealed a dislocated posterior tibial tendon (PTT) that was temporarily reducible, but would spontaneously dislocate immediately after reduction. She had pain and snapping of the PTT with resisted ankle plantar flexion and resisted inversion as well as 4/5 strength in ankle inversion. The diagnosis of dislocated PTT was confirmed on magnetic resonance imaging (MRI). The patient underwent suture anchor repair of the medial retinaculum of the left ankle. At the time of surgery both the PTT and flexor digitorum longus (FDL) were dislocated. Three months postoperatively, the patient represented with PTT dislocation of the right (nonoperative) ankle confirmed by MRI. After failure of immobilization, physical therapy, and oral anti-inflammatory medications, the patient underwent suture anchor repair of the medial retinaculum of the right ankle. At 6 months postoperatively, the patient has 5/5 strength inversion bilaterally, no subluxation of either PTT, and has returned to all activities without limitation. The authors present this unique case of bilateral PTT dislocation and concurrent PTT/FDL dislocation along with review of the literature for PTT dislocation. The authors highlight the common misdaiganosis of this injury and highlight the successful results of surgical intervention. Level V: Case report.

  17. Exploring the Limit of Dislocation Based Plasticity in Nanostructured Metals

    DEFF Research Database (Denmark)

    Hughes, D. A.; Hansen, Niels

    2014-01-01

    A twofold decrease to an unexplored scale of 5 nm was produced in Cu by applying a large sliding load in liquid nitrogen. Statistical and universal scaling analyses of deformation induced high angle boundaries, dislocation boundaries, and individual dislocations observed by high resolution electron...

  18. Cellular growth and dislocation structures in laser-nitrided titanium

    NARCIS (Netherlands)

    Kloosterman, A.B.; Hosson, J.Th.M. De

    1997-01-01

    Transmission electron microscopic observations were made of different dislocation structures in laser-nitrided titanium. Equidistant edge dislocations in the bulk and periodic surface structures exhibit a periodicity within the same order of magnitude. An analysis is presented in which both periodic

  19. Edge dislocations in dicalcium silicates: Experimental observations and atomistic analysis

    International Nuclear Information System (INIS)

    Shahsavari, Rouzbeh; Chen, Lu; Tao, Lei

    2016-01-01

    Understanding defects and influence of dislocations on dicalcium silicates (Ca 2 SiO 4 ) is a challenge in cement science. We report a high-resolution transmission electron microscopy image of edge dislocations in Ca 2 SiO 4 , followed by developing a deep atomic understanding of the edge dislocation-mediated properties of five Ca 2 SiO 4 polymorphs. By decoding the interplay between core dislocation energies, core structures, and nucleation rate of reactivity, we find that γ-C2S and α-C2S polymorphs are the most favorable polymorphs for dislocations in Ca 2 SiO 4 , mainly due to their large pore channels which take away majority of the distortions imposed by edge dislocations. Furthermore, in the context of edge dislocation, while α-C2S represents the most active polymorph for reactivity and crystal growth, β-C2S represents the most brittle polymorph suitable for grinding. This work is the first report on the atomistic-scale analysis of edge dislocation-mediated properties of Ca 2 SiO 4 and may open up new opportunities for tuning fracture and reactivity processes of Ca 2 SiO 4 and other cement components.

  20. Atomic-scale dislocation dynamics in radiation damage environment

    International Nuclear Information System (INIS)

    Osetsky, Y.; Stoller, R.; Bacon, D.J.

    2007-01-01

    Full text of publication follows: The dynamics behavior of dislocations determines mechanical properties of crystalline materials. Long-range interactions between a moving dislocation and other defects can be treated within a continuum approach via interaction of their stress and strain fields. However, a vast contribution to mechanical properties depends on the direct interaction between dislocations and other defects and depends very much on the particular atomic scale structure of the both moving dislocation core and the obstacle. In this work we review recent progress in large-scale modeling of dislocation dynamics in metals at the atomic level by molecular dynamics and statics. We review the modem techniques used to simulate dynamics of dislocations in different lattice structures, the dependence on temperature, strain rate and obstacle size. Examples are given for bcc, fcc and hcp metals where edge and screw dislocations interact with vacancy (loops, voids, stacking fault tetrahedra, etc), self-interstitial clusters and secondary phase precipitates. Attention is paid to interpretation of atomistic results from the point of view of parameterization of continuum models. The latter is vitally necessary for further application in 3-dimensional dislocation dynamics within the multi-scale materials modeling approach. Research sponsored by the Division of Materials Sciences and Engineering and the Office of Fusion Energy Sciences, U.S. Department of Energy, under contract DE-AC0S-00OR22725 with UT-Battelle, LLC. (authors)

  1. Discrete dislocation plasticity modeling of short cracks in single crystals

    NARCIS (Netherlands)

    Deshpande, VS; Needleman, A; Van der Giessen, E

    2003-01-01

    The mode-I crack growth behavior of geometrically similar edge-cracked single crystal specimens of varying size subject to both monotonic and cyclic axial loading is analyzed using discrete dislocation dynamics. Plastic deformation is modeled through the motion of edge dislocations in an elastic

  2. Isolated posterior dislocation of the radial head in an adult.

    Directory of Open Access Journals (Sweden)

    Negi A

    1992-07-01

    Full Text Available Isolated posterior dislocation of the radial head was detected on X-ray in a patient following a vehicular accident. Such a dislocation without an associated fracture is extremely rare in adults. Immobilization of the elbow in full pronation and 90 degrees flexion for 4 weeks normalized the position of the head of the radius.

  3. Lateral subtalar dislocation : Case report and review of the literature

    NARCIS (Netherlands)

    Veltman, Ewout S; Steller, Ernst Ja; Wittich, Philippe; Keizer, Jort

    2016-01-01

    A case of complicated lateral subtalar dislocation is presented and the literature concerning this injury is reviewed. Subtalar joint dislocations are rare and often the result of a high-energy trauma. Complications include avascular necrosis of the talus, infection, posttraumatic osteoarthritis

  4. Bosonic and fermionic dipoles on a ring

    DEFF Research Database (Denmark)

    Zöllner, Sascha; Pethick, C. J.; Bruun, Georg Morten

    2011-01-01

    We show that dipolar bosons and fermions confined in a quasi-one-dimensional ring trap exhibit a rich variety of states because their interaction is inhomogeneous. For purely repulsive interactions, with increasing strength of the dipolar coupling there is a crossover from a gaslike state...... to an inhomogeneous crystal-like one. For small enough angles between the dipoles and the plane of the ring, there are regions with attractive interactions, and clustered states can form....

  5. The LHC AC Dipole system: an introduction

    CERN Document Server

    Serrano, J; CERN. Geneva. BE Department

    2010-01-01

    The LHC AC Dipole is an instrument to study properties of the LHC lattice by inducing large transverse displacements in the beam. These displacements are generated by exciting the beam with an oscillating magnetic field at a frequency close to the tune. This paper presents the system requirements and the technical solution chosen to meet them, based of high-power audio amplifiers and a resonant parallel RLC circuit.

  6. Field quality of LHC superconducting dipole magnets

    International Nuclear Information System (INIS)

    Mishra, R.K.

    2003-01-01

    The author reports here the main results of field measurements performed so far on the LHC superconducting dipoles at superfluid helium temperature. The main field strength at injection, collision conditions and higher order multipoles are discussed. Superconducting magnets exhibit additional field imperfections due to diamagnetic properties of superconducting cables, apart from geometric error, saturation of iron yoke and eddy currents error. Dynamic effects on field harmonics, such as field decay at injection and subsequent snap back are also discussed. (author)

  7. 15 T And Beyond - Dipoles and Quadrupoles

    International Nuclear Information System (INIS)

    Sabbi, GianLuca

    2008-01-01

    Starting with the invention of the cyclotron by Lawrence, accelerator-based experiments have been the primary source of new discoveries in particle physics. In order to progress toward higher energy and luminosity, higher field magnets are required. R and D programs are underway to take advantage of new developments in superconducting materials, achieve better efficiency and simplify magnet fabrication while preserving accelerator-class field quality. A review of recent progress on high field dipole and quadrupole magnets is presented.

  8. Extended equivalent dipole model for radiated emissions

    OpenAIRE

    Obiekezie, Chijioke S.

    2016-01-01

    This work is on the characterisation of radiated fields from electronic devices. An equivalent dipole approach is used. Previous work showed that this was an effective approach for single layer printed circuit boards where an infinite ground plane can be assumed. In this work, this approach is extended for the characterisation of more complex circuit boards or electronic systems.\\ud For complex electronic radiators with finite ground planes, the main challenge is characterising field diffract...

  9. Electric dipole transitions of heavy quarkonium

    Energy Technology Data Exchange (ETDEWEB)

    Pietrulewicz, Piotr [Universitaet Wien (Austria)

    2012-07-01

    In this talk we present the theoretical treatment of electric dipole transitions of heavy quarkonia within an effective field theory formalism. Inside the effective field theory called potential nonrelativistic QCD (pNRQCD) we account for the relativistic corrections to the decay rate in a systematic and model-independent way. Former results from potential model calculations are scrutinized, and a phenomenological analysis in relation to the experimental data is presented.

  10. CP-violation and electric dipole moments

    Energy Technology Data Exchange (ETDEWEB)

    Le Dall, Matthias; Ritz, Adam, E-mail: aritz@uvic.ca [University of Victoria, Department of Physics and Astronomy (Canada)

    2013-03-15

    Searches for intrinsic electric dipole moments of nucleons, atoms and molecules are precision flavour-diagonal probes of new -odd physics. We review and summarise the effective field theory analysis of the observable EDMs in terms of a general set of CP-odd operators at 1 GeV, and the ensuing model-independent constraints on new physics. We also discuss the implications for supersymmetric models, in light of the mass limits emerging from the LHC.

  11. Magnetic field modification of optical magnetic dipoles.

    Science.gov (United States)

    Armelles, Gaspar; Caballero, Blanca; Cebollada, Alfonso; Garcia-Martin, Antonio; Meneses-Rodríguez, David

    2015-03-11

    Acting on optical magnetic dipoles opens novel routes to govern light-matter interaction. We demonstrate magnetic field modification of the magnetic dipolar moment characteristic of resonant nanoholes in thin magnetoplasmonic films. This is experimentally shown through the demonstration of the magneto-optical analogue of Babinet's principle, where mirror imaged MO spectral dependencies are obtained for two complementary magnetoplasmonic systems: holes in a perforated metallic layer and a layer of disks on a substrate.

  12. Mechanism and energetics of dislocation cross-slip in hcp metals

    Science.gov (United States)

    Wu, Zhaoxuan; Curtin, W. A.

    2016-10-01

    Hexagonal close-packed (hcp) metals such as Mg, Ti, and Zr are lightweight and/or durable metals with critical structural applications in the automotive (Mg), aerospace (Ti), and nuclear (Zr) industries. The hcp structure, however, brings significant complications in the mechanisms of plastic deformation, strengthening, and ductility, and these complications pose significant challenges in advancing the science and engineering of these metals. In hcp metals, generalized plasticity requires the activation of slip on pyramidal planes, but the structure, motion, and cross-slip of the associated dislocations are not well established even though they determine ductility and influence strengthening. Here, atomistic simulations in Mg reveal the unusual mechanism of dislocation cross-slip between pyramidal I and II planes, which occurs by cross-slip of the individual partial dislocations. The energy barrier is controlled by a fundamental step/jog energy and the near-core energy difference between pyramidal dislocations. The near-core energy difference can be changed by nonglide stresses, leading to tension-compression asymmetry and even a switch in absolute stability from one glide plane to the other, both features observed experimentally in Mg, Ti, and their alloys. The unique cross-slip mechanism is governed by common features of the generalized stacking fault energy surfaces of hcp pyramidal planes and is thus expected to be generic to all hcp metals. An analytical model is developed to predict the cross-slip barrier as a function of the near-core energy difference and applied stresses and quantifies the controlling features of cross-slip and pyramidal I/II stability across the family of hcp metals.

  13. Arthroscopic repair of acute traumatic anterior shoulder dislocation in young athletes.

    Science.gov (United States)

    Larrain, M V; Botto, G J; Montenegro, H J; Mauas, D M

    2001-04-01

    To compare the results of arthroscopic repair in acute anterior shoulder traumatic dislocation with those of nonoperative treatment. A prospective nonrandomized study was performed. Between August 1989 and April 1997, 46 patients were seen after a first episode of traumatic anterior shoulder dislocation. The average age was 21 years (range, 17 to 27 years). Most dislocations were in rugby players (36 patients). There were 18 patients treated by nonoperative methods and 28 patients treated by acute arthroscopic repair; 22 patients using transglenoid suture and 6 patients with bone anchor suture fixation. Of the patients treated nonoperatively, 94.5% suffered a redislocation between 4 and 18 months (average, 6 months). In the operative group, 96% of the patients (27) obtained excellent results according to the Rowe scale. Only 1 patient suffered a redislocation 1 year after surgery. Three different types of lesions were found during surgery: group I, capsular tear with no labrum lesion (4%); group II, capsular tear with partial labrum detachment (32%); and group III, capsular tear and full anterior labrum detachment (64%). The average follow-up was 67.4 months (range, 28 to 120). There were no surgical complications. The operative group obtained 96% excellent results, but the nonoperative group only obtained 5.5% excellent results, according to the Rowe scale. The nonoperative group showed a high incidence of redislocation (94.5%) compared with the operative group (4%). Based on the findings of this study, we recommend using an arthroscopic evaluation and repair after an initial anterior traumatic shoulder dislocation in young athletes.

  14. SPS Dipole Multipactor Test and TEWave Diagnostics

    CERN Document Server

    Caspers, F; Edwards, P; Federmann, S; Holz, M; Taborelli, M

    2013-01-01

    Electron cloud accumulation in particle accelerators can be mitigated by coating the vacuum beam pipe with thin films of low secondary electron yield (SEY) material. The SEY of small coated samples are usually measured in the laboratory. To further test the properties of different coating materials, RF-induced multipacting in a coaxial waveguide configuration can be performed. The technique is applied to two main bending dipoles of the SPS, where the RF power is fed through a tungsten wire stretched along the vacuum chamber (6.4 m). A dipole with a bare stainless steel chamber shows a clear power threshold initiating an abrupt rise in reflected power and pressure. The effect is enhanced at RF frequencies corresponding to electron cyclotron resonances for given magnetic fields. Preliminary results show that the dipole with a carbon coated vacuum chamber does not exhibit any pressure rise or reflected RF power up to the maximum available input power. In the case of a large scale coating production this techniqu...

  15. Direct amplitude detuning measurement with ac dipole

    Directory of Open Access Journals (Sweden)

    S. White

    2013-07-01

    Full Text Available In circular machines, nonlinear dynamics can impact parameters such as beam lifetime and could result in limitations on the performance reach of the accelerator. Assessing and understanding these effects in experiments is essential to confirm the accuracy of the magnetic model and improve the machine performance. A direct measurement of the machine nonlinearities can be obtained by characterizing the dependency of the tune as a function of the amplitude of oscillations (usually defined as amplitude detuning. The conventional technique is to excite the beam to large amplitudes with a single kick and derive the tune from turn-by-turn data acquired with beam position monitors. Although this provides a very precise tune measurement it has the significant disadvantage of being destructive. An alternative, nondestructive way of exciting large amplitude oscillations is to use an ac dipole. The perturbation Hamiltonian in the presence of an ac dipole excitation shows a distinct behavior compared to the free oscillations which should be correctly taken into account in the interpretation of experimental data. The use of an ac dipole for direct amplitude detuning measurement requires careful data processing allowing one to observe the natural tune of the machine; the feasibility of such a measurement is demonstrated using experimental data from the Large Hadron Collider. An experimental proof of the theoretical derivations based on measurements performed at injection energy is provided as well as an application of this technique at top energy using a large number of excitations on the same beam.

  16. Strength of Dislocation Junctions in FCC-monocrystals with a [\\overline{1}11] Deformation Axis

    Science.gov (United States)

    Kurinnaya, R. I.; Zgolich, M. V.; Starenchenko, V. A.

    2017-07-01

    The paper examines all dislocation reactions implemented in FCC-monocrystals with axis deformation oriented in the [\\overline{1}11] direction. It identifies the fracture stresses of dislocation junctions depending on intersection geometry of the reacting dislocation loop segments. Estimates are produced for the full spectrum of reacting forest dislocations. The paper presents the statistical data of the research performed and identifies the share of long strong dislocation junctions capable of limiting the zone of dislocation shift.

  17. Molecular dynamics simulation of dislocations in uranium dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Fossati, Paul [CEA, DEN, DPC, SCCME, F-91191 Gif-sur-Yvette Cedex (France); Van Brutzel, Laurent, E-mail: laurent.vanbrutzel@cea.fr [CEA, DEN, DPC, SCCME, F-91191 Gif-sur-Yvette Cedex (France); Devincre, Benoît [LEM, CNRS-ONERA, 29 avenue de la Division Leclerc, F-92322 Châtillon Cedex (France)

    2013-11-15

    The plasticity of the fluorite structure in UO{sub 2} is investigated with molecular dynamics simulation and empirical potential. The stacking fault energies and the dislocation core structures with Burgers vector a/2 〈110〉 are systematically calculated. All dislocation core structures show a significant increase of the oxygen sub-lattice disorder at temperatures higher than 1500 K. The threshold stress for dislocation glide is found to decrease with increasing temperature but its values is always very high, several GPa at 0 K and several hundred of MPa at 2000 K. A relation between the dislocation mobility dependence with temperature and the increase of the oxygen sub-lattice disorder in the dislocation cores is established.

  18. Neglected Posterior Dislocation of Hip in Children - A Case Report.

    Science.gov (United States)

    Pal, Chandra Prakash; Kumar, Deepak; Sadana, Ashwani; Dinkar, Karuna Shankar

    2014-01-01

    Traumatic dislocation of the hip in children is a rare injury. We report the outcome of 2 patients of neglected hip dislocation which were treated by open reduction and internal fixation by k-wires. We treat 2 children both girls (one was of 4 years and other was 7 years of age). In both cases dislocation was unilateral and was not associated with any facture. Both cases were of posterior dislocation. in both cases open reduction and internal fixation was done by k wires. Hip spica was applied post operatively in both cases. The k wire was removed at 3 to 4 weeks. Patients were allowed to bear weight from gradual to full weight bearing after 6 weeks. We conclude that open reduction is a satisfactory treatment for neglected hip dislocation. It prevents not only deformity but also maintains limb length.

  19. Influence of strain on dislocation core in silicon

    Science.gov (United States)

    Pizzagalli, L.; Godet, J.; Brochard, S.

    2018-05-01

    First principles, density functional-based tight binding and semi-empirical interatomic potentials calculations are performed to analyse the influence of large strains on the structure and stability of a 60? dislocation in silicon. Such strains typically arise during the mechanical testing of nanostructures like nanopillars or nanoparticles. We focus on bi-axial strains in the plane normal to the dislocation line. Our calculations surprisingly reveal that the dislocation core structure largely depends on the applied strain, for strain levels of about 5%. In the particular case of bi-axial compression, the transformation of the dislocation to a locally disordered configuration occurs for similar strain magnitudes. The formation of an opening, however, requires larger strains, of about 7.5%. Furthermore, our results suggest that electronic structure methods should be favoured to model dislocation cores in case of large strains whenever possible.

  20. Modeling of dislocation dynamics in germanium Czochralski growth

    Science.gov (United States)

    Artemyev, V. V.; Smirnov, A. D.; Kalaev, V. V.; Mamedov, V. M.; Sidko, A. P.; Podkopaev, O. I.; Kravtsova, E. D.; Shimansky, A. F.

    2017-06-01

    Obtaining very high-purity germanium crystals with low dislocation density is a practically difficult problem, which requires knowledge and experience in growth processes. Dislocation density is one of the most important parameters defining the quality of germanium crystal. In this paper, we have performed experimental study of dislocation density during 4-in. germanium crystal growth using the Czochralski method and comprehensive unsteady modeling of the same crystal growth processes, taking into account global heat transfer, melt flow and melt/crystal interface shape evolution. Thermal stresses in the crystal and their relaxation with generation of dislocations within the Alexander-Haasen model have been calculated simultaneously with crystallization dynamics. Comparison to experimental data showed reasonable agreement for the temperature, interface shape and dislocation density in the crystal between calculation and experiment.

  1. Self-force on dislocation segments in anisotropic crystals

    International Nuclear Information System (INIS)

    Fitzgerald, S P; Aubry, S

    2010-01-01

    A dislocation segment in a crystal experiences a 'self-force', by virtue of the orientation dependence of its elastic energy. If the crystal is elastically isotropic, this force is manifested as a couple acting to rotate the segment toward the lower energy of the pure screw orientation (i.e. acting to align the dislocation line with its Burgers vector). If the crystal is anisotropic, there are additional contributions to the couple, arising from the more complex energy landscape of the lattice itself. These effects can strongly influence the dynamic evolution of dislocation networks, and via their governing role in dislocation multiplication phenomena, control plastic flow in metals. In this paper we develop a model for dislocation self-forces in a general anisotropic crystal, and briefly consider the technologically important example of α-iron, which becomes increasingly anisotropic as the temperature approaches that of the α-γ phase transition at 912 0 C.

  2. Dislocation Interactions in Olivine Revealed by HR-EBSD

    Science.gov (United States)

    Wallis, David; Hansen, Lars N.; Britton, T. Ben; Wilkinson, Angus J.

    2017-10-01

    Interactions between dislocations potentially provide a control on strain rates produced by dislocation motion during creep of rocks at high temperatures. However, it has been difficult to establish the dominant types of interactions and their influence on the rheological properties of creeping rocks due to a lack of suitable observational techniques. We apply high-angular resolution electron backscatter diffraction to map geometrically necessary dislocation (GND) density, elastic strain, and residual stress in experimentally deformed single crystals of olivine. Short-range interactions are revealed by cross correlation of GND density maps. Spatial correlations between dislocation types indicate that noncollinear interactions may impede motion of proximal dislocations at temperatures of 1000°C and 1200°C. Long-range interactions are revealed by autocorrelation of GND density maps. These analyses reveal periodic variations in GND density and sign, with characteristic length scales on the order of 1-10 μm. These structures are spatially associated with variations in elastic strain and residual stress on the order of 10-3 and 100 MPa, respectively. Therefore, short-range interactions generate local accumulations of dislocations, leading to heterogeneous internal stress fields that influence dislocation motion over longer length scales. The impacts of these short- and/or long-range interactions on dislocation velocities may therefore influence the strain rate of the bulk material and are an important consideration for future models of dislocation-mediated deformation mechanisms in olivine. Establishing the types and impacts of dislocation interactions that occur across a range of laboratory and natural deformation conditions will help to establish the reliability of extrapolating laboratory-derived flow laws to real Earth conditions.

  3. Dislocation pinning effects induced by nano-precipitates during warm laser shock peening: Dislocation dynamic simulation and experiments

    Science.gov (United States)

    Liao, Yiliang; Ye, Chang; Gao, Huang; Kim, Bong-Joong; Suslov, Sergey; Stach, Eric A.; Cheng, Gary J.

    2011-07-01

    Warm laser shock peening (WLSP) is a new high strain rate surface strengthening process that has been demonstrated to significantly improve the fatigue performance of metallic components. This improvement is mainly due to the interaction of dislocations with highly dense nanoscale precipitates, which are generated by dynamic precipitation during the WLSP process. In this paper, the dislocation pinning effects induced by the nanoscale precipitates during WLSP are systematically studied. Aluminum alloy 6061 and AISI 4140 steel are selected as the materials with which to conduct WLSP experiments. Multiscale discrete dislocation dynamics (MDDD) simulation is conducted in order to investigate the interaction of dislocations and precipitates during the shock wave propagation. The evolution of dislocation structures during the shock wave propagation is studied. The dislocation structures after WLSP are characterized via transmission electron microscopy and are compared with the results of the MDDD simulation. The results show that nano-precipitates facilitate the generation of highly dense and uniformly distributed dislocation structures. The dislocation pinning effect is strongly affected by the density, size, and space distribution of nano-precipitates.

  4. High temperature dislocation processes in precipitation hardened crystals investigated by a 3D discrete dislocation dynamics

    Czech Academy of Sciences Publication Activity Database

    Záležák, Tomáš; Svoboda, Jiří; Dlouhý, Antonín

    2017-01-01

    Roč. 97, OCT (2017), s. 1-23 ISSN 0749-6419 R&D Projects: GA ČR(CZ) GA14-22834S; GA ČR(CZ) GA202/09/2073; GA ČR(CZ) GD106/09/H035; GA MŠk(CZ) EE2.3.20.0214; GA MŠk OC 162 EU Projects: European Commission(XE) 309916 - Z-ULTRA Institutional support: RVO:68081723 Keywords : 3D discrete dislocation dynamics * Dislocations * Strengthening mechanisms * Low angle grain boundaries * Particulate reinforced material Subject RIV: JI - Composite Materials OBOR OECD: Composites (including laminates, reinforced plastics, cermets, combined natural and synthetic fibre fabrics Impact factor: 5.702, year: 2016

  5. Communication: Permanent dipoles contribute to electric polarization in chiral NMR spectra

    International Nuclear Information System (INIS)

    Buckingham, A. David

    2014-01-01

    Nuclear magnetic resonance spectroscopy is blind to chirality because the spectra of a molecule and its mirror image are identical unless the environment is chiral. However, precessing nuclear magnetic moments in chiral molecules in a strong magnetic field induce an electric polarization through the nuclear magnetic shielding polarizability. This effect is equal and opposite for a molecule and its mirror image but is small and has not yet been observed. It is shown that the permanent electric dipole moment of a chiral molecule is partially oriented through the antisymmetric part of the nuclear magnetic shielding tensor, causing the electric dipole to precess with the nuclear magnetic moment and producing a much larger temperature-dependent electric polarization with better prospects of detection

  6. Dislocation density and graphitization of diamond crystals

    International Nuclear Information System (INIS)

    Pantea, C.; Voronin, G.A.; Zerda, T.W.; Gubicza, J.; Ungar, T.

    2002-01-01

    Two sets of diamond specimens compressed at 2 GPa at temperatures varying between 1060 K and 1760 K were prepared; one in which graphitization was promoted by the presence of water and another in which graphitization of diamond was practically absent. X-ray diffraction peak profiles of both sets were analyzed for the microstructure by using the modified Williamson-Hall method and by fitting the Fourier coefficients of the measured profiles by theoretical functions for crystallite size and lattice strain. The procedures determined mean size and size distribution of crystallites as well as the density and the character of the dislocations. The same experimental conditions resulted in different microstructures for the two sets of samples. They were explained in terms of hydrostatic conditions present in the graphitized samples

  7. Stress field of a dislocating inclined fault

    Energy Technology Data Exchange (ETDEWEB)

    Huang, F.; Wang, T.

    1980-02-01

    Analytical expressions are derived for the stress field caused by a rectangular dislocating fault of an arbitrary dip in a semi-infinite elastic medium for the case of unequal Lame constants. The results of computations for the stress fields on the ground surface of an inclined strike-slip and an inclined dip-slip fault are represented by contour maps. The effects of Poisson Ratio of the medium, the dip angle, upper and lower boundaries of the faults on the stress field at surface have been discussed. As an application, the contour maps for shear stress and hydrostatic stress of near fields of the Tonghai (1970), Haicheng (1975) and Tangshan (1976) earthquakes have been calculated and compared with the spatial distributions of strong aftershocks of these earthquakes. It is found that most of the strong aftershocks are distributed in the regions of tensional stress, where the hydrostatic stress is positive.

  8. Stress field of a dislocating inclined fault

    Energy Technology Data Exchange (ETDEWEB)

    Huang, F.; Wang, T.

    1980-02-01

    In this paper, analytical expressions of the stress field given rise by a rectangular dislocating fault of an arbitrary dip in a semi-infinite elastic medium for the case of unequal Lame constants are derived. The results of computations for the stress fields on the ground surface of an inclined strike-slip and an inclined dip-slip fault are represented by contour maps. The effects of the Poisson Ratio of the medium, the dip angle, upper and lower boundaries of the faults on the stress field at the surface have been discussed. As an application, the contour maps for shear stress and hydrostatic stress of near fields of the Tonghai (1970), Haicheng, (1975) and Tangshan (1976) earthquakes have been calculated and compared with the spatial distributions of strong aftershocks of these earthquakes. It is found that most of the strong aftershocks are distributed in the regions of tensional stress where the hydrostatic stress is positive.

  9. Handling of the posttraumatic knee dislocation

    International Nuclear Information System (INIS)

    Lara Cotassio, Gilberto; Quevedo Blanco, Sonia Mercedes

    2003-01-01

    Knee dislocation although not common, is a potentially devastating entity. it is necessary to make an immediate diagnosis and begin a treatment plan to prevent vascular complications. Due to their low incidence, and because series about this topic have few patients included, there still is no concern in the world literature about treatment. The goal is to avoid rigidity and instability. We present a report of 11 patients treated in the Hospital Central de la Policia Nacional, which entered the hospital between 1994 and 2001. Results have not been good in the non-operated group and in those taken late to surgery. On the other hand, patients, operated Carlier had satisfactory clinical results. We propose the repair of all the ligamentous structures by arthrotomy in a single surgical time during the first 3 weeks after trauma

  10. Anisotropic Dislocation Line Energy and Crack Tip Dislocation Nucleation in (alpha)RDX

    Science.gov (United States)

    2013-11-01

    Mitchell, R.L.; Knap, J.; Chung, P.W., Role of molecule flexibility on the nucleation of dislocations in molecular crystals. App. Phys. Lett. 2013...uniform stres , under-estimate of stressses (Get from S) Br=0; for i=1:3 Br=Br+sum(S(i,1:3)); end Br=1/Br; % Shear Modulus Gr=4/15*(S(1,1

  11. Dislocation evolution and properties enhancement of GH2036 by laser shock processing: Dislocation dynamics simulation and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Ren, X.D., E-mail: renxd@mail.ujs.edu.cn [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); Zhou, W.F.; Ren, Y.P.; Xu, S.D.; Liu, F.F. [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); Yuan, S.Q. [Research Center of Fluid Machinery Engineering and Technical, Jiangsu University, Zhenjiang 212013 (China); Ren, N.F.; Huang, J.J. [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2016-01-27

    This paper systematically investigated the effect of laser shock processing (LSP) on dislocation evolution and microstructure configuration of GH2036 alloy. Surface topography and roughness were tested by Axio CSM 700 microscope. The dislocation configurations were characterized by transmission electron microscope (TEM) and simulated by multi-scale discrete dislocation dynamics (DD) method. The results have confirmed that LSP had a beneficial effect on micro-hardness, which could be increased by 16%, and the surface topography exhibited excellent stability even after thermal cycle. The dislocation density and stress–strain response have strong dependence on laser power intensity. Reasonable agreement between DD simulation and experiments is achieved. The results showed that complex random microstructures can be observed in the shocked surface. The grain refinement mechanism of LSP GH2036 involves dislocation segmentation and twin intersections.

  12. The effect of length scale on the determination of geometrically necessary dislocations via EBSD continuum dislocation microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ruggles, T.J., E-mail: timmyruggs@gmail.com [National Institute of Aerospace, 100 Exploration Way, Hampton, VA 23666 (United States); Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602 (United States); Rampton, T.M. [EDAX Inc., 91 McKee Drive, Mahwah, NJ 07430 (United States); Khosravani, A. [Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Fullwood, D.T. [Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602 (United States)

    2016-05-15

    Electron backscatter diffraction (EBSD) dislocation microscopy is an important, emerging field in metals characterization. Currently, calculation of geometrically necessary dislocation (GND) density is problematic because it has been shown to depend on the step size of the EBSD scan used to investigate the sample. This paper models the change in calculated GND density as a function of step size statistically. The model provides selection criteria for EBSD step size as well as an estimate of the total dislocation content. Evaluation of a heterogeneously deformed tantalum specimen is used to asses the method. - Highlights: • The GND to SSD transition with increasing step size is analytically modeled. • Dislocation density of a microindented tantalum single crystal is measured. • Guidelines for step size selection in EBSD dislocation microscopy are presented.

  13. Disclinations, dislocations, and continuous defects: A reappraisal

    Science.gov (United States)

    Kleman, M.; Friedel, J.

    2008-01-01

    Disclinations were first observed in mesomorphic phases. They were later found relevant to a number of ill-ordered condensed-matter media involving continuous symmetries or frustrated order. Disclinations also appear in polycrystals at the edges of grain boundaries; but they are of limited interest in solid single crystals, where they can move only by diffusion climb and, owing to their large elastic stresses, mostly appear in close pairs of opposite signs. The relaxation mechanisms associated with a disclination in its creation, motion, and change of shape involve an interplay with continuous or quantized dislocations and/or continuous disclinations. These are attached to the disclinations or are akin to Nye’s dislocation densities, which are particularly well suited for consideration here. The notion of an extended Volterra process is introduced, which takes these relaxation processes into account and covers different situations where this interplay takes place. These concepts are illustrated by a variety of applications in amorphous solids, mesomorphic phases, and frustrated media in their curved habit space. These often involve disclination networks with specific node conditions. The powerful topological theory of line defects considers only defects stable against any change of boundary conditions or relaxation processes compatible with the structure considered. It can be seen as a simplified case of the approach considered here, particularly suited for media of high plasticity or/and complex structures. It cannot analyze the dynamical properties of defects nor the elastic constants involved in their static properties; topological stability cannot guarantee energetic stability, and sometimes cannot distinguish finer details of the structure of defects.

  14. Size-dependent plastic deformation characteristics in He-irradiated nanostructured Cu/Mo multilayers: Competition between dislocation-boundary and dislocation-bubble interactions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J.Y.; Zeng, F.L.; Wu, K.; Wang, Y.Q.; Liang, X.Q.; Liu, G., E-mail: lgsammer@mail.xjtu.edu.cn; Zhang, G.J.; Sun, J., E-mail: junsun@mail.xjtu.edu.cn

    2016-09-15

    Nanoindentation methodology was used to investigate the plastic deformation characteristics, including the hardness (H), strain rate sensitivity (SRS, m) and activation volume (V{sup *}), of Cu/Mo nanostructured metallic multilayers (NMMs) with equal layer thickness (h) spanning from 10 to 200 nm before and after He-implantation at room temperature. Compared with the as-deposited Cu/Mo NMMs, the irradiated Cu/Mo samples exhibited the enhanced hardness particularly at great h, which is caused by the bubble-hardening effect. Unlike the as-deposited Cu/Mo NMMs displayed a monotonic increase in SRS (or a monotonic decrease in activation volume) with reducing h, the irradiated Cu/Mo samples manifested an unexpected non-monotonic variation in SRS as well as in activation volume. It was clearly unveiled that the SRS of irradiated Cu/Mo firstly decreased with reducing h down to a critical size of ~50 nm and subsequently increased with further reducing h, leaving a minimum value at the critical h. These phenomena are rationalized by considering a competition between dislocation-boundary and dislocation-bubble interactions. A thermally activated model based on the depinning process of bowed-out partial dislocations was employed to quantitatively account for the size-dependent SRS of Cu/Mo NMMs before and after irradiation. Our findings not only provide fundamental understanding of the effects of radiation-induced defects on plastic characteristics of NMMs, but also offer guidance for their microstructure sensitive design for performance optimization at extremes.

  15. Origins and implications of temperature-dependent activation energy barriers for dislocation nucleation in face-centered cubic metals

    International Nuclear Information System (INIS)

    Warner, D.H.; Curtin, W.A.

    2009-01-01

    The linking of atomistic simulations of stress-driven processes to experimentally observed mechanical behavior via the computation of activation energy barriers is a topic of intense current research. Using dislocation nucleation from a crack tip as the reaction process, long-time multiscale molecular dynamics simulations show that the activation barrier can exhibit significant temperature dependence. Using an analytic model for the nucleation process and computing the relevant material properties (elastic constants and stacking fault energies), the temperature dependence is shown to arise primarily from the temperature dependence of the material parameters for both Al and Ni. After thermally activated emission of the first partial dislocation, there is then a competition between two other thermally activated processes: twinning and full dislocation emission. Because the activation barriers depend on temperature, this transition is more complex than usually envisioned. Simulations in Al reveal that a transition from twinning to full dislocation emission back to twinning occurs with increasing temperature, which is counter to traditional metallurgical wisdom. Temperature-dependent activation energies are thus essential to accurate understanding and prediction of those phenomena that control fracture and deformation in metals at realistic loading rates.

  16. Proposal for Translational Entanglement of Dipole-Dipole Interacting Atoms in Optical Lattices

    Science.gov (United States)

    Opatrný, Tomáš; Deb, Bimalendu; Kurizki, Gershon

    2003-06-01

    We propose and investigate a realization of the position- and momentum-correlated Einstein-Podolsky-Rosen (EPR) states [Phys. Rev. 47, 777 (1935)] that have hitherto eluded detection. The realization involves atom pairs that are confined to adjacent sites of two mutually shifted optical lattices and are entangled via laser-induced dipole-dipole interactions. The EPR “paradox” with translational variables is then modified by lattice-diffraction effects and can be verified to a high degree of accuracy in this scheme.

  17. Vortical structures for nanomagnetic memory induced by dipole-dipole interaction in monolayer disks

    Science.gov (United States)

    Liu, Zhaosen; Ciftja, Orion; Zhang, Xichao; Zhou, Yan; Ian, Hou

    2018-05-01

    It is well known that magnetic domains in nanodisks can be used as storage units for computer memory. Using two quantum simulation approaches, we show here that spin vortices on magnetic monolayer nanodisks, which are chirality-free, can be induced by dipole-dipole interaction (DDI) on the disk-plane. When DDI is sufficiently strong, vortical and anti-vortical multi-domain textures can be generated simultaneously. Especially, a spin vortex can be easily created and deleted through either external magnetic or electrical signals, making them ideal to be used in nanomagnetic memory and logical devices. We demonstrate these properties in our simulations.

  18. Lens dislocation has a possible relationship with laser iridotomy

    Directory of Open Access Journals (Sweden)

    Mutoh T

    2012-12-01

    Full Text Available Tetsuya Mutoh,1,2 Kevin F Barrette,2 Yukihiro Matsumoto,1 Makoto Chikuda11Department of Ophthalmology, Dokkyo Medical University Koshigaya Hospital, Koshigaya City, Saitama, Japan; 2Department of Ophthalmology, Boston University School of Medicine, Boston, MA, USAAbstract: We report our recent experience of four eyes with spontaneous lens dislocation in four patients with no history of trauma or any systemic disease associated with zonular dialysis. Lens dislocation developed with 0.5 to 6 months following laser iridotomy. All patients were male and two eyes were complicated with acute primary angle closure glaucoma preoperatively. Case 1 showed bilateral lens dislocation, while cases 2 and 3 involved unilateral lens dislocation. Cases 2 and 3 showed lenses completely dislocated into the vitreous cavity. All cases needed lens removal and scleral fixation of intraocular lenses. Final visual acuity was 1.2 in all cases. We suspect that laser iridotomy may induce localized zonular dialysis that results in progressive zonular weakness, leading to lens dislocation.Keywords: lens dislocation, laser iridotomy, primary angle closure glaucoma

  19. Dislocation dynamics modelling of radiation damage in thin films

    International Nuclear Information System (INIS)

    Ferroni, Francesco; Tarleton, Edmund; Fitzgerald, Steven

    2014-01-01

    Transmission electron microscopy is a key tool for the extraction of information on radiation damage, the understanding of which is critical for materials development for nuclear fusion and fission reactors. Dislocations in TEM samples are subject to strong image forces, owing to the nanometric sample thicknesses, which may introduce artifacts in the damage analysis. Using dislocation dynamics, we elucidate the roles played by dislocation–surface interactions, dislocation–dislocation interactions and self-interactions due to climb for loop types observed in TEM. Comparisons with analytic solutions for a dislocation loop and an edge dislocation in a half-space are included, and the relationship between glide force and loop tilt examined. The parameters for convergence of the zero-traction boundary conditions are obtained, after which the evolution of dislocation structures in a thin film is studied. It is found that three main length scales govern the physical processes: the image force is governed by the distance of the loop from the surface and scales with the film thickness; the glide force is governed by the image stress as well as the loop–loop interaction stress which is in turn governed by the loop spacing L∼1/√ρ, where ρ is the loop density; finally, the climb force depends on the loop size. The three forces compete and their relative magnitudes define the evolution pathway of the dislocation structure. (paper)

  20. Dislocation following total knee arthroplasty: A report of six cases

    Directory of Open Access Journals (Sweden)

    Villanueva Manuel

    2010-01-01

    Full Text Available Background: Dislocation following total knee arthroplasty (TKA is the worst form of instability. The incidence is from 0.15 to 0.5%. We report six cases of TKA dislocation and analyze the patterns of dislocation and the factors related to each of them. Materials and Methods: Six patients with dislocation of knee following TKA are reported. The causes for the dislocations were an imbalance of the flexion gap (n=4, an inadequate selection of implants (n=1, malrotation of components (n=1 leading to incompetence of the extensor mechanism, or rupture of the medial collateral ligament (MCC. The patients presented complained of pain, giving way episodes, joint effusion and difficulty in climbing stairs. Five patients suffered posterior dislocation while one anterior dislocation. An urgent closed reduction of dislocation was performed under general anaesthesia in all patients. All patients were operated for residual instability by revision arthroplasty after a period of conservative treatment. Results: One patient had deep infection and knee was arthrodesed. Two patients have a minimal residual lag for active extension, including a patient with a previous patellectomy. Result was considered excellent or good in four cases and fair in one, without residual instability. Five out of six patients in our series had a cruciate retaining (CR TKA designs: four were revised to a posterior stabilized (PS TKA and one to a rotating hinge design because of the presence of a ruptured MCL. Conclusion: Further episodes of dislocation or instability will be prevented by identifying and treating major causes of instability. The increase in the level of constraint and correction of previous technical mistakes is mandatory.

  1. ACCELERATION OF POLARIZED BEAMS USING MULTIPLE STRONG PARTIAL SIBERIAN SNAKES

    International Nuclear Information System (INIS)

    ROSER, T.; AHRENS, L.; BAI, M.

    2004-01-01

    Acceleration of polarized protons in the energy range of 5 to 25 GeV is particularly difficult since depolarizing spin resonances are strong enough to cause significant depolarization but full Siberian snakes cause intolerably large orbit excursions. Using a 20-30% partial Siberian snake both imperfection and intrinsic resonances can be overcome. Such a strong partial Siberian snake was designed for the Brookhaven AGS using a dual pitch helical superconducting dipole. Multiple strong partial snakes are also discussed for spin matching at beam injection and extraction

  2. Nanoscale shift of the intensity distribution of dipole radiation.

    Science.gov (United States)

    Shu, Jie; Li, Xin; Arnoldus, Henk F

    2009-02-01

    The energy flow lines (field lines of the Poynting vector) for radiation emitted by a dipole are in general curves, rather than straight lines. For a linear dipole the field lines are straight, but when the dipole moment of a source rotates, the field lines wind numerous times around an axis, which is perpendicular to the plane of rotation, before asymptotically approaching a straight line. We consider an elliptical dipole moment, representing the most general state of oscillation, and this includes the linear dipole as a special case. Due to the spiraling near the source, for the case of a rotating dipole moment, the field lines in the far field are displaced with respect to the outward radial direction, and this leads to a shift of the intensity distribution of the radiation in the far field. This shift is shown to be independent of the distance to the source and, although of nanoscale dimension, should be experimentally observable.

  3. Radiological difficulty in identifying unicompartmental knee replacement dislocation

    Directory of Open Access Journals (Sweden)

    Mr Oruaro Adebayo Onibere, MBBS, MRCS

    2017-09-01

    Full Text Available Unicondylar knee replacement is a relatively common elective orthopedic procedure but is not often seen in the Emergency Department setting. Familiarity with normal clinical and radiological appearances is difficult to gain. Dislocation of the mobile bearing component “spacer” is a known complication of unicondylar knee replacements, and these patients will initially present to the accident and Emergency Department. In this setting, an accurate and prompt diagnosis is necessary to appropriately manage the patient's condition. There is normally a radiological challenge in identifying dislocated mobile bearings on plain radiographs. These patients may need to have further imaging, such as a computer tomographic scan to identify the dislocated mobile bearing.

  4. Bilateral Posterior Native Hip Dislocations after Fall from Standing

    Directory of Open Access Journals (Sweden)

    Jane Xiao

    2017-10-01

    Full Text Available We present a case of bilateral posterior native hip dislocations after a fall from standing. This exceedingly rare diagnosis is classically associated with younger patients whose bones are strong enough to dislocate rather than fracture in the setting of a high-momentum collision. We present an unusual case of an 88-year-old male with native hips who sustained a low-energy collision after falling from standing and was found to have bilateral posterior hip dislocations without associated pelvis or femur fractures.

  5. Positron-trapping mechanism at dislocations in Zn

    DEFF Research Database (Denmark)

    Hidalgo, Carlos; Linderoth, Søren; Diego, Nieves de

    1987-01-01

    the average lifetime and the intensity of the long component decrease with increasing temperature. The experimental results are very well described in terms of a generalized trapping model where it is assumed that positrons become trapped in deep traps (jogs) via shallow traps (dislocation lines......). The temperature dependence of the positron-lifetime spectra below 120 K is attributed to the temperature dependence of the trapping rate to the dislocation line. The experimental results have demonstrated that detrapping processes from the dislocation line take place above 120 K. The positron binding energy...

  6. Ubiquity of quantum zero-point fluctuations in dislocation glide

    Science.gov (United States)

    Landeiro Dos Reis, Marie; Choudhury, Anshuman; Proville, Laurent

    2017-03-01

    Modeling the dislocation glide through atomic scale simulations in Al, Cu, and Ni and in solid solution alloys Al(Mg) and Cu(Ag), we show that in the course of the plastic deformation the variation of the crystal zero-point energy (ZPE) and the dislocation potential energy barriers are of opposite sign. The multiplicity of situations where we have observed the same trend allows us to conclude that quantum fluctuations, giving rise to the crystal ZPE, make easier the dislocation glide in most materials, even those constituted of atoms heavier than H and He.

  7. Slip systems, dislocation boundaries and lattice rotations in deformed metals

    DEFF Research Database (Denmark)

    Winther, Grethe

    2009-01-01

    Metals are polycrystals and consist of grains, which are subdivided on a finer scale upon plastic deformation due to formation of dislocation boundaries. The crystallographic alignment of planar dislocation boundaries in face centred cubic metals, like aluminium and copper, deformed to moderate...... of the mechanical anisotropy of rolled sheets. The rotation of the crystallographic lattice in each grain during deformation also exhibits grain orientation dependence, originating from the slip systems. A combined analysis of dislocation boundaries and lattice rotations concludes that the two phenomena are coupled...

  8. Structure of dipole bands in 106In

    International Nuclear Information System (INIS)

    Deo, A. Y.; Palit, R.; Naik, Z.; Joshi, P. K.; Mazumdar, I.; Sihotra, S.; Mehta, D.; Kumar, S.; Chakrabarti, R.; Kshetri, R.; Jain, H. C.

    2009-01-01

    High spin states in neutron-deficient 106 In were investigated using 78 Se( 32 S,p3n) reaction at 125 MeV. The level scheme is extended up to 7 MeV of excitation energy for the negative parity states constituting four dipole bands, and the positive parity states which mainly exhibit single-particle excitations are extended up to 5 MeV. Projected deformed Hartree-Fock calculations were carried out to understand the configurations of different bands in this nucleus.

  9. Magnetic monopoles and dipoles in quantum mechanics

    International Nuclear Information System (INIS)

    Lipkin, H.J.; Peshkin, M.

    1986-01-01

    The force on and the energy of a ''di-monopole'', which is the limiting case of a dipole made from two monopoles at zero separation and finite magnetic moment, interacting with an externally fixed magnetic field resulting from an electric current, is considered. A model involving only a monopole is used to illustrate the physical principles involved when magnetic sources move in a solenoidal field whose source is an electric current. The problems encountered in Hamiltonian theory are discussed. 5 refs., 3 figs

  10. Directional Dipole Model for Subsurface Scattering

    DEFF Research Database (Denmark)

    Frisvad, Jeppe Revall; Hachisuka, Toshiya; Kjeldsen, Thomas Kim

    2014-01-01

    Rendering translucent materials using Monte Carlo ray tracing is computationally expensive due to a large number of subsurface scattering events. Faster approaches are based on analytical models derived from diffusion theory. While such analytical models are efficient, they miss out on some...... point source diffusion. A ray source corresponds better to the light that refracts through the surface of a translucent material. Using this ray source, we are able to take the direction of the incident light ray and the direction toward the point of emergence into account. We use a dipole construction...

  11. Temperature dependence of giant dipole resonance width

    International Nuclear Information System (INIS)

    Vdovin, A.I.; Storozhenko, A.N.

    2005-01-01

    The quasiparticle-phonon nuclear model extended to finite temperature within the framework of the thermo field dynamics is applied to calculate a temperature dependence of the spreading width Γ d own of a giant dipole resonance. Numerical calculations are made for 12S n and 208 Pb nuclei. It is found that the width Γ d own increases with T. The reason of this effect is discussed as well as a relation of the present approach to other ones existing in the literature

  12. The AGL equation from the dipole picture

    International Nuclear Information System (INIS)

    Gay Ducati, M.B.; Goncalves, V.P.

    1999-01-01

    The AGL equation includes all multiple pomeron exchanges in the double logarithmic approximation (DLA) limit, leading to a unitarized gluon distribution in the small x regime. This equation was originally obtained using the Glauber-Mueller approach. We demonstrate in this paper that the AGL equation and, consequently, the GLR equation, can also be obtained from the dipole picture in the double logarithmic limit, using an evolution equation, recently proposed, which includes all multiple pomeron exchanges in the leading logarithmic approximation. Our conclusion is that the AGL equation is a good candidate for a unitarized evolution equation at small x in the DLA limit

  13. Effective gluon operators and neutron dipole moment

    International Nuclear Information System (INIS)

    Bigi, I.; Ural'tsev, N.G.

    1991-01-01

    The role of the purely gluon CP odd six-dimension effective arising in various CP-breaking models is discussed. This operators of most interest in the nonminimal Higgs sector models, the right W models and supersymmetric theories, where it may induce the neutron dipole moment at the level of the experimental restriction. The method for evaluating the magnitude d n is proposed and the reasons are given in favor that the original Weiberg's estimate based on the naive Dimensional Analysis is overdone significantly. The Peccei -Quinn mechanism, impact on the magnitude of d n , which generally may be very essential, is discussed

  14. Electric dipole moment of 3He

    International Nuclear Information System (INIS)

    Avishai, Y.; Fabre de la Ripelle, M.

    1986-01-01

    The contribution of a CP-nonconserving nucleon-nucleon interaction to the electric dipole moment of 3 He is evaluated in view of a recent proposal for its experimental detection. We use two models of CP-nonconserving interactions in combination with a Reid soft-core strong nucleon-nucleon interaction. In the Kobayashi-Maskawa model of CP nonconservation the order of magnitude is 10 -30 eX while the presence of the theta term in the QCD Langrangian contributes an order of magnitude 10 -16 theta-bar e cm

  15. The universal function in color dipole model

    Science.gov (United States)

    Jalilian, Z.; Boroun, G. R.

    2017-10-01

    In this work we review color dipole model and recall properties of the saturation and geometrical scaling in this model. Our primary aim is determining the exact universal function in terms of the introduced scaling variable in different distance than the saturation radius. With inserting the mass in calculation we compute numerically the contribution of heavy productions in small x from the total structure function by the fraction of universal functions and show the geometrical scaling is established due to our scaling variable in this study.

  16. Collective Hamiltonians for dipole giant resonances

    International Nuclear Information System (INIS)

    Weiss, L.I.

    1991-07-01

    The collective hamiltonian for the Giant Dipole resonance (GDR), in the Goldhaber-Teller-Model, is analytically constructed using the semiclassical and generator coordinates method. Initially a conveniently parametrized set of many body wave functions and a microscopic hamiltonian, the Skyrme hamiltonian - are used. These collective Hamiltonians are applied to the investigation of the GDR, in He 4 , O 16 and Ca 40 nuclei. Also the energies and spectra of the GDR are obtained in these nuclei. The two sets of results are compared, and the zero point energy effects analysed. (author)

  17. Direct photons and dileptons via color dipoles

    International Nuclear Information System (INIS)

    Kopeliovich, B.Z.; Rezaeian, A.H.; Pirner, H.J.; Schmidt, Ivan

    2007-01-01

    Drell-Yan dilepton pair production and inclusive direct photon production can be described within a unified framework in the color dipole approach. The inclusion of non-perturbative primordial transverse momenta and DGLAP evolution is studied. We successfully describe data for dilepton spectra from 800-GeV pp collisions, inclusive direct photon spectra for pp collisions at RHIC energies √(s)=200 GeV, and for pp-bar collisions at tevatron energies √(s)=1.8 TeV, in a formalism that is free from any extra parameters

  18. High temperature giant dipole and isoscalar resonances

    International Nuclear Information System (INIS)

    Navarro, J.; Barranco, M.; Garcias, F.; Suraud, E.

    1990-01-01

    We present a systematic study of the Giant Dipole Resonance (GDR) at high temperatures (T > ∼ 4 MeV) in the framework of a semi-classical approximation that uses the m 1 and m 3 RPA sum rules to estimate the GDR mean energy. We focus on the evolution with T of the collective nature of the GDR and of the L = 0,2,3 and 4 isoscalar resonances. We find that the GDR remains particularly collective at high T, suggesting that it might be possible to observe it experimentally even at temperatures close to the maximum one a nucleus can sustain

  19. Field simulations for large dipole magnets

    International Nuclear Information System (INIS)

    Lazzaro, A.; Cappuzzello, F.; Cunsolo, A.; Cavallaro, M.; Foti, A.; Khouaja, A.; Orrigo, S.E.A.; Winfield, J.S.

    2007-01-01

    The problem of the description of magnetic field for large bending magnets is addressed in relation to the requirements of modern techniques of trajectory reconstruction. The crucial question of the interpolation and extrapolation of fields known at a discrete number of points is analysed. For this purpose a realistic field model of the large dipole of the MAGNEX spectrometer, obtained with finite elements three dimensional simulations, is used. The influence of the uncertainties in the measured field to the quality of the trajectory reconstruction is treated in detail. General constraints for field measurements in terms of required resolutions, step sizes and precisions are thus extracted

  20. Giant dipole resonance in hot nuclei

    International Nuclear Information System (INIS)

    Mau, N.V.

    1993-01-01

    Giant resonances built on an excited state of the nucleus at a finite temperature T are studied. The following questions are investigated: how long such collective effects occur in a nucleus when T increases. How the properties of the giant resonances vary when the temperature increases. How the study of giant resonances in hot nuclei can give information on the structure of the nucleus in a highly excited state. The special case of the giant dipole resonance is studied. Some of the experimental results are reviewed and in their theoretical interpretation is discussed. (K.A.). 56 refs., 20 figs., 4 tabs