Cluster observations of surface waves on the dawn flank magnetopause

On 14 June 2001 the four Cluster spacecraft recorded multiple encounters of the dawn-side flank magnetopause. The characteristics of the observed electron populations varied between a cold, dense magnetosheath population and warmer, more rarified boundary layer population on a quasi-periodic basis. The demarcation between these two populations can be readily identified by gradients in the scalar temperature of the electrons. An analysis of the differences in the observed timings of the boundary at each spacecraft indicates that these magnetopause crossings are consistent with a surface wave moving across the flank magnetopause. When compared to the orientation of the magnetopause expected from models, we find that the leading edges of these waves are approximately 45° steeper than the trailing edges, consistent with the Kelvin-Helmholtz (KH) driving mechanism. A stability analysis of this interval suggests that the magnetopause is marginally stable to this mechanism during this event. Periods in which the analysis predicts that the magnetopause is unstable correspond to observations of greater wave steepening. Analysis of the pulses suggests that the waves have an average wavelength of approximately 3.4 <i>R<sub>E</sub></i> and move at an average speed of ~65km s<sup>-1</sup> in an anti-sunward and northward direction, despite the spacecraft location somewhat south of the GSE <i>Z=0</i> plane. This wave propagation direction lies close to perpendicular to the average magnetic field direction in the external magnetosheath, suggesting that these waves may preferentially propagate in the direction that requires no bending of these external field lines<br><br> <b>Key words.</b> Magnetospheric physics (magnetospheric configuration and dynamics; MHD waves and unstabilities; solar wind-magnetosphere interactions

ВЛИЯНИЕ МНОГОСТЕННЫХ НАНОТРУБОК НА ПРИВИВКУ ТРАНС-ЭТИЛЕН-1,2-ДИКАРБОНОВОЙ КИСЛОТЫ К МАКРОМОЛЕКУЛАМ ПОЛИОЛЕФИНОВ

A study was conducted on the effect of multiwalled carbon nanotubes (MWNT) on the course of free-radical grafting of trans-ethylene-1,2-dicarboxylic acid (TEDA) onto linear low-density polyethylene (LLDPE) and ethylene-propylene copolymer (cPP), containing ethylene units ≈ 7 wt%, using the reactive extrusion process. The extrusion reactor was the material cylinder of the twin-screw extruder TSSK-35/40 (screw diameter = 35 mm; L/D = 40; 10 independent heating zones).It was found that small amounts of MWNT (0.01–0.3 wt%) influence noticeably the monomer grafting onto macromolecules of LLDPE and cPP, as well as the structure, functionalized products’ mechanical properties, strength and high elasticity properties of their melts. The extent of MWNT influence depends on their concentration and PO-structure. It is shown that the monomer’s grafting efficiency can be raised with MWNT ≥ 0.1 wt% inhibit the secondary process of macromolecular cross-linking; in the case of cPP which mostly undergoes degradation during functionalization, the secondary reactions accelerate catalytically.Исследовано влияние многостенных нанотрубок (МУНТ) на протекание свободнорадикальной прививки транс-этилен-1,2-дикарбоновой кислоты к линейному полиэтилену низкой плотности (ЛПЭНП) и сополимеру этилена с пропиленом (сПП) с содержанием звеньев этилена ≈7 масс. %, осуществляемой методом реакционной экструзии. В качестве экструзионного реактора использовали материальный цилиндр двухшнекового экструдера TSSK-35/40 (диаметр шнеков 35 мм, L/D = 40, число независимых зон обогрева 10).Установлено, что малые добавки МУНТ (0,01–0,3 масс. %) оказывают заметное влияние на ход прививки мономера к макромолекулам ЛПЭНП и сПП, а также структуру, механические свойства функционализированных продуктов, прочность и высокоэластичность их расплавов. Степень влияния добавок МУНТ определяется их концентрацией и природой ПО. Показана возможность повышения эффективности прививки мономера при концентрации МУНТ в реакционной системе ≈0,05 масс. %.Для сшивающегося при свободнорадикальной прививке ЛПЭНП добавки МУНТ, вводимые в количестве ≥0,1 масс. %, ингибируют побочный процесс сшивания макромолекул, а для сПП, преимущественно деструктирующего при функционализации, наблюдается каталитическое ускорение побочных реакций