Reverse Satellite Transionospheric Sounding: Advantages and Prospects

This chapter includes four sections. The first introduction section provides a brief review of the existing methods of transionospheric sounding and the results obtained, and the shortcomings of each are noted. The second section describes the proposed principle based on the installation of a receiver on the GLONASS platform. The advantages and technical characteristics of the proposed system are justified. The main area of use is the polar region. The third section presents the most modern modeling methods and models used. To calculate the propagation of radio waves, this is a method of ray tracing taking into account the large- and small-scale inhomogeneities of the ionosphere. To describe the state of the ionosphere, it is proposed to use the IRI2016 model, which includes adaptation to the current diagnostic data provided by ground ionosondes, and the IRI-Plas model, which not only can be adapted to ground ionosonde data, but also to values of the total electronic content, the measurement of which is an additional advantage of the proposed system. The fourth sectionincludes areas of application, the main of which is the monitoring of the polar region, and the least provided with ionospheric information

The Radiation Transfer at a Layer of Magnetized Plasma With Random Irregularities

The problem of radio wave reflection from an optically thick plane monotonous layer of magnetized plasma is considered at present work. The plasma electron density irregularities are described by spatial spectrum of an arbitrary form. The small-angle scattering approximation in the invariant ray coordinates is suggested for analytical investigation of the radiation transfer equation. The approximated solution describing spatial-and-angular distribution of radiation reflected from a plasma layer has been obtained. The obtained solution has been investigated numerically for the case of the ionospheric radio wave propagation. Two effects are the consequence of multiple scattering: change of the reflected signal intensity and anomalous refraction.Comment: 22 pages, 4 figure

Modeling of forging process in asymmetric combined anvils

Проведений аналіз наукових робот в області кування, із якого встановлена позитивна роль деформацій зсуву на розмір зерен в поковці і як наслідок рівень її механічних властивостей. Методом скінченних елементів проведено моделювання процесу обтиску заготовки в комбінованих бойках. Встановлено напружено-деформований стан заготовки при її куванні комбінованими бойками різного розміру. Визначено вплив геометричних параметрів комбінованих бойків на рівень деформацій зсуву в заготовці. Дано рекомендації по призначенню режиму кування і розмірів комбінованих бойків, що забезпечують високий рівень деформацій зсуву в поперечному перерізі заготовки.Purpose. The aim of this paper is in investigation of strain-stress state of billet during the forging by asymmetric anvils and determining of them dimensions which provide high level of shear deformations. Design/methodology/approach. Researches were made by the finite element method. Boundary conditions are the next. Diameter of billet 1000 mm, width of anvils 1000 mm. Relative feed is one. Material of billet is steel with carbon content 0.35%, initial temperature of billet is 1100 °C, of instrument is 20 °C. Heat transfer coefficient is 5 W/m² °C. Friction coefficient by Zibel law is 0.35, speed of anvils move is 10 mm/sec. Findings. It is determined influence of tools geometric parameters in forging processes upon to level of shear deformations in billet. Originality/value. The recommendations of determining the tools parameters and regime of forging process which are provide a high level of shear deformations in billet were given.Проведен анализ научных робот в области ковки, из которого установлена положительная роль деформаций сдвига на размер зерна в поковке и как следствие уровень ее механических свойств. Методом конечных элементов проведено моделирование процесса обжатия заготовки в комбинированных бойках. Установлено напряженно-деформированное состояние заготовки при ее ковке комбинированными бойками различного размера. Определено влияние геометрических параметров комбинированных бойков на уровень деформаций сдвига в заготовке. Даны рекомендации по назначению режима ковки и размеров комбинированных бойков, которые обеспечивают высокий уровень сдвиговых деформаций в поперечном сечении заготовки

Application of the nudged elastic band method to the point-to-point radio wave ray tracing in IRI modeled ionosphere

Point-to-point ray tracing is an important problem in many fields of science. While direct variational methods where some trajectory is transformed to an optimal one are routinely used in calculations of pathways of seismic waves, chemical reactions, diffusion processes, etc., this approach is not widely known in ionospheric point-to-point ray tracing. We apply the Nudged Elastic Band (NEB) method to a radio wave propagation problem. In the NEB method, a chain of points which gives a discrete representation of the radio wave ray is adjusted iteratively to an optimal configuration satisfying the Fermat’s principle, while the endpoints of the trajectory are kept fixed according to the boundary conditions. Transverse displacements define the radio ray trajectory, while springs between the points control their distribution along the ray. The method is applied to a study of point-to-point ionospheric ray tracing, where the propagation medium is obtained with the International Reference Ionosphere model taking into account traveling ionospheric disturbances. A 2-dimensional representation of the optical path functional is developed and used to gain insight into the fundamental difference between high and low rays. We conclude that high and low rays are minima and saddle points of the optical path functional, respectively.The authors thank F.S. Bessarab and V.V. Klimenko for fruitful discussions. This study was financially supported by Grants from the Russian Foundation for Basic Research (RFBR) Nos. 15-35-20364, 16-35-00590, Russian target Federal program 5-100 and the task of the Ministry of Education and Science, project No. 3.1127.2014/K.Peer Reviewe

Phase Equilibria in the AgGaS 2 −l/2(CdGa 2 S 4 )−2/3(As 2 S 3 ) System.

Фазові рівноваги в квазіпотрійній системі досліджено методами диференційно-термічного та рентгено- фазового аналізів. Побудовано два політермічних перерізи, проекцію поверхні ліквідусу і встановлено область склоутворення. The alloys of this system were investigated by means of differential thermal and X-ray phase analysis; the phase diagram of two politermal section, liquidus surface projection and glassforming region have been constructed based on this results

Generalized Force Approach to Point-to-Point Ionospheric Ray Tracing and Systematic Identification of High and Low Rays

Post-print (lokagerð höfundar)A variant of the direct optimization method for point-to-point ionospheric ray tracing is presented. The method is well suited for applications where the launch direction of the radio wave ray is unknown, but the position of the receiver is specified instead. Iterative transformation of a candidate path to the sought-for ray is guided by a generalized force, where the definition of the force depends on the ray type. For high rays, the negative gradient of the optical path functional is used. For low rays, the transformation of the gradient is applied, converting the neighbourhood of a saddle point to that of a local minimum. Knowledge about the character of the rays is used to establish a scheme for systematic identification of all relevant rays between given points, without the need to provide an accurate initial estimate for each solution. Various applications of the method to isotropic ionosphere demonstrate its ability to resolve complex ray configurations including three-dimensional propagation and multi-path propagation where rays are close in the launch direction. Results of the application of the method to ray tracing between Khabarovsk and Tory show good quantitative agreement with the measured oblique ionograms.Icelandic Research Fund (Grant No. 184949-052)Peer Reviewe

Anomalous attenuation of extraordinary waves in the ionosphere heating experiments

Multiple scattering of radio waves by artificial random irregularities HF-induced in the ionosphere F region may cause significant attenuation of both ordinary and extraordinary waves together with common anomalous absorption of ordinary waves due to their non-linear conversion into plasma waves. To demonstrate existence and strength of this effect, direct measurements of attenuation of both powerful pump wave and weak probing waves of extraordinary polarization have been carried out during an experimental campaign on September 6, 7 and 9, 1999 at the Sura heating facility. The attenuation magnitude of extraordinary waves reaches of 1-10 dB over a background attenuation caused by natural irregularities. It is interpreted in the paper on the base of the theory of multiple scattering from the artificial random irregularities with characteristic scale lengths of 0.1-1 km. Simple procedure for determining of irregularity spectrum parameters from the measured attenuation of extraordinary waves has been implemented and some conclusions about the artificial irregularity formation have been obtained.Comment: 17 pages, 9 figure