May 12 1997 Cme Event: I. a Simplified Model of the Pre-Eruptive Magnetic Structure

A simple model of the coronal magnetic field prior to the CME eruption on May 12 1997 is developed. First, the magnetic field is constructed by superimposing a large-scale background field and a localized bipolar field to model the active region (AR) in the current-free approximation. Second, this potential configuration is quasi-statically sheared by photospheric vortex motions applied to two flux concentrations of the AR. Third, the resulting force-free field is then evolved by canceling the photospheric magnetic flux with the help of an appropriate tangential electric field applied to the central part of the AR. To understand the structure of the modeled configuration, we use the field line mapping technique by generalizing it to spherical geometry. It is demonstrated that the initial potential configuration contains a hyperbolic flux tube (HFT) which is a union of two intersecting quasi-separatrix layers. This HFT provides a partition of the closed magnetic flux between the AR and the global solar magnetic field. The vortex motions applied to the AR interlock the field lines in the coronal volume to form additionally two new HFTs pinched into thin current layers. Reconnection in these current layers helps to redistribute the magnetic flux and current within the AR in the flux-cancellation phase. In this phase, a magnetic flux rope is formed together with a bald patch separatrix surface wrapping around the rope. Other important implications of the identified structural features of the modeled configuration are also discussed.Comment: 25 pages, 11 figures, to appear in ApJ 200

Towards the electron EDM search: Theoretical study of HfF+

We report first ab initio relativistic correlation calculations of potential curves for ten low-lying electronic states, effective electric field on the electron and hyperfine constants for the ^3\Delta_1 state of cation of a heavy transition metal fluoride, HfF^+, that is suggested to be used as the working state in experiments to search for the electric dipole moment of the electron. It is shown that HfF^+ has deeply bound ^1\Sigma^+ ground state, its dissociation energy is D_e=6.4 eV. The ^3\Delta_1 state is obtained to be the relatively long-lived first excited state lying about 0.2 eV higher. The calculated effective electric field E_eff=W_d|\Omega| acting on an electron in this state is 5.84*10^{24}Hz/(e*cm)Comment: 4 page

Ensuring the quality of the connection of layers from different metals in the manufacture of bietallic tubular elements by drawing

. Запропонована комплексна методика теоретичного та експериментального дослідження процесу виготовлення біметалевих трубчастих елементів витягуванням з потоншенням двошарової заготовки з різнорідних металів з використанням рельєфу граничної поверхні. Використовуючи теорію пластичної течії розроблена математична модель деформування процесу сумісного витягування з потоншенням двох різнорідних металів з нагрівом в умовах плоского деформованого стану, яка дозволила встановити взаємозв’язок параметрів напружено-деформованого стану на граничній поверхні і ступеню деформації потоншення з вихідними геометричними параметрами заготовки, та проаналізувати необхідні умови для заповнення рельєфу граничної поверхні.A complex technique of theoretical and experimental research of the process of manufacturing bimetallic tubular elements by drawing with thinning of a two-layer billet of dissimilar metals using the relief of the boundary surface is presented. Using the theory of plastic flow, a mathematical model was developed for the deformation of the joint drawing process with thinning of two dissimilar metals with heating under conditions of a plane deformed state, which allowed to establish the relationship between the parameters of the stress-strain state on the boundary surface and the degree of deformation of the thinning with the original geometric parameters of the workpiece to fill the relief of the boundary surface.Представлена комплексная методика теоретического и экспериментального исследования процесса изготовления биметаллических трубчатых элементов вытяжкой с утонением двухслойной заготовки из разнородных металлов с использованием рельефа граничной поверхности. Используя теорию пластического течения разработана математическая модель деформирования процесса совместной вытяжки с утонением двух разнородных металлов с нагревом в условиях плоского деформированного состояния, которая позволила установить взаимосвязь параметров напряженно-деформированного состояния на граничной поверхности и степени деформации утонения с исходными геометрическими параметрами заготовки, и проанализировать необходимые условия для заполнения рельефа граничной поверхности

Ballistic charge transport in chiral-symmetric few-layer graphene

A transfer matrix approach to study ballistic charge transport in few-layer graphene with chiral-symmetric stacking configurations is developed. We demonstrate that the chiral symmetry justifies a non-Abelian gauge transformation at the spectral degeneracy point (zero energy). This transformation proves the equivalence of zero-energy transport properties of the multilayer to those of the system of uncoupled monolayers. Similar transformation can be applied in order to gauge away an arbitrary magnetic field, weak strain, and hopping disorder in the bulk of the sample. Finally, we calculate the full-counting statistics at arbitrary energy for different stacking configurations. The predicted gate-voltage dependence of conductance and noise can be measured in clean multilayer samples with generic metallic leads.Comment: 6 pages, 5 figures; EPL published versio

A Model for the Sources of the Slow Solar Wind

Models for the origin of the slow solar wind must account for two seemingly contradictory observations: The slow wind has the composition of the closed field corona, implying that it originates from the continuous opening and closing of flux at the boundary between open and closed field. On the other hand, the slow wind also has large angular width, up to ~ 60{\circ}, suggesting that its source extends far from the open-closed boundary. We propose a model that can explain both observations. The key idea is that the source of the slow wind at the Sun is a network of narrow (possibly singular) open-field corridors that map to a web of separatrices and quasi-separatrix layers in the heliosphere. We compute analytically the topology of an open-field corridor and show that it produces a quasi-separatrix layer in the heliosphere that extends to angles far from the heliospheric current sheet. We then use an MHD code and MDI/SOHO observations of the photospheric magnetic field to calculate numerically, with high spatial resolution, the quasi-steady solar wind and magnetic field for a time period preceding the August 1, 2008 total solar eclipse. Our numerical results imply that, at least for this time period, a web of separatrices (which we term an S-web) forms with sufficient density and extent in the heliosphere to account for the observed properties of the slow wind. We discuss the implications of our S-web model for the structure and dynamics of the corona and heliosphere, and propose further tests of the model