МОДЕЛЬ И АЛГОРИТМ ДЛЯ РАСЧЕТА ЭФФЕКТИВНОЙ ПЛОЩАДИ РАССЕЯНИЯ ИМИТАТОРА РАДИОЛОКАЦИОННОГО ОБЪЕКТА

To reduce the cost of field tests of the ballistic objects (BO) simulators reflection properties, it is advisable to develop a model and algorithm for calculation of the radar objects effective surface scattering. As a simulator of ballistic objects a complex radar reflector, made of a lossfree dielectric is chosen. It looks like a spherical Luneburg lens with a coating of high-conductivity alloy as well as a truncated cone, disk, and cylindrical elements. The stages of aperture version of reflection from the inner surface of the Luneburg lens are proposed. A physical model of the reflection on the elements of design and the technique of modeling with a calculation algorithm of the effective surface scattering are developed. The algorithm of calculation of the ballistic objects resonance effective surface scattering is worked out. This algorithm is presented in a graphical form. The interface of the computing complex is presented. As a simulator of ballistic object we selected a complex radar reflector, made of a lossfree dielectric sphere with a coating of high-conductivity alloy as well as of a truncated cone, disk, and cylindrical elements. The comparative indicatrices of ballistic objects simulator are presented. The conclusion on the comparative analysis of the results of measurements in situ and modeling results is made. The examples of numerical calculations of the ESR of the head part of the BO simulator with increased ESR and increased all-aspect view are given. The options of the BO simulator head parts with increased ESR and increased all-aspect view with optimal placement of radar dielectric reflector and a corner unit with sectional placement of dielectric reflectors are analyzed.Для сокращения затрат на натурные испытания отражающих свойств имитаторов баллистических объектов (БО) целесообразно разработать модель и алгоритм для расчета эффективной поверхности рассеяния таких радиолокационных объектов. В качестве имитатора баллистических объектов выбирается сложный радиолокационный отражатель, изготовленный из диэлектрика без потерь в виде сферической линзы Люнеберга с покрытием из высокоэлектропроводного сплава, а также усеченного конуса, диска и цилиндрических элементов. Предложены этапы апертурного варианта отражения от внутренней поверхности линзы Люнеберга. Разработана физическая модель отражения на элементах конструкции и методика моделирования с алгоритмом расчета эффективной поверхности рассеяния. Разработан алгоритм расчета резонансной эффективной поверхности рассеяния баллистических объектов. Этот алгоритм представлен в графическом виде. Представлен интерфейс вычислительного комплекса. В качестве имитатора баллистического объекта выбран сложный радиолокационный отражатель, изготовленный из диэлектрика без потерь в виде сферы с покрытием из высокоэлектропроводного сплава, а также усеченного конуса, диска и цилиндрических элементов. Графически представлены сравнительные индикатрисы имитатора баллистических объектов. Сделан вывод по сравнительному анализу результатов измерения в натурных условиях и результатов моделирования. Приведены примеры численных расчетов ЭПР головной части имитатора БО с увеличенной ЭПР и увеличенной всеракурсностью обзора. Исследованы варианты головных частей имитатора БО с увеличенной ЭПР и увеличенной всеракурсностью обзора с оптимальным размещением радиолокационного диэлектрического отражателя и уголкового блока с секционным размещением диэлектрических отражателей

Experimental evidence for the preservation of U-Pb isotope ratios in mantle-recycled crustal zircon grains

Zircon of crustal origin found in mantle-derived rocks is of great interest because of the information it may provide about crust recycling and mantle dynamics. Consideration of this requires understanding of how mantle temperatures, notably higher than zircon crystallization temperatures, affected the recycled zircon grains, particularly their isotopic clocks. Since Pb2+ diffuses faster than U4+ and Th+4, it is generally believed that recycled zircon grains lose all radiogenic Pb after a few million years, thus limiting the time range over which they can be detected. Nonetheless, this might not be the case for zircon included in mantle minerals with low Pb2+ diffusivity and partitioning such as olivine and orthopyroxene because these may act as zircon sealants. Annealing experiments with natural zircon embedded in cristobalite (an effective zircon sealant) show that zircon grains do not lose Pb to their surroundings, although they may lose some Pb to molten inclusions. Diffusion tends to homogenize the Pb concentration in each grain changing the U-Pb and Th-Pb isotope ratios proportionally to the initial 206Pb, 207Pb and 208Pb concentration gradients (no gradient-no change) but in most cases the original age is still recognizable. It seems, therefore, that recycled crustal zircon grains can be detected, and even accurately dated, no matter how long they have dwelled in the mantle.This paper has been financed by the Spanish Grants CGL2013-40785-P and CGL2017-84469-P

Physical-chemical conditions and composition of ore-building fluids of Russian oroganic gold deposits

The detailed research of fluid inclusions and stable isotopes in minerals of industrial ore veins large-scale orogenic gold deposits of different regions of Russia was carried out. The deposits under investigation are Berezovsk and Kochkarskoye (Ural), Olympiada (the Yenisei Ridge), Mayskoye (Chukotka), Nezhdaninskoye (Yakutiya) and Sukhoy Log (Eastern Siberia). Temperatures of industrial ores formation for all investigated deposits are stacked in an interval 190-485 \ubaС. Fluid pressure under ore formations changed from 1.0 up to 3.6 kbar. The hydrothermal fluid of all orogenic gold deposits under investigation is a low-mineralized water solution with the general concentration of salts 2-17 % in weight, and sodium and potassium chlorides are prevailed. For fluids from the majority of deposits the high concentrations of dissolved CO2 (3-7 mol/kg H2O) with a small impurity of other gases are characteristic. Variations of geochemical ratio volumes for K/Rb, Br/Cl and others which can serve as indicators of the ore-forming fluid natures are established. Au-bearing fluid from all deposits had the magmatic nature and had mixed up with formation solutions under ore sediments