ON THE REPRESENTATION AERODROME SURFACEROUTING NETWORK EDGE BY SMOOTH CURVES

The actual problem of ways to represent aerodrome surface route network is considered. Based on the analysis of various options, an approach is proposed for representing route network sections as smooth curves, which are described by parametric vector functions. Each of the vector function components is represented by a two-point Hermite interpolation polynomial, which uses derivatives up to some order inclusive. Within this approach, the optimization problem related to the coefficients selection of these polynomials based on minimizing the distance between the broken line and smooth curve is solved. The problem is reduced to solving a system of linear equations by the derivatives values at the ends of the route network section. The corresponding finite formulas for approximating broken lines by smooth curves are proposed. Based on the formulas obtained, algorithm and program for approximating route network sections using information about taxi lines, which are stored in aerodrome mapping database (AMDB), were developed. The program also allows you to calculate statistical indicators, what allow to get a quantitative approximation estimate. Numerical experiments based on the Sheremetyevo aerodrome dataset have shown the promise of this approach to presenting aerodrome surface route network, which can significantly (2 – 4 times) reduce the amount of data and increase the realism of the aerodrome model.

Дислокационные реакции в полуполярном слое GaN, выращенном на вицинальной подложке Si(001) с использованием буферных слоев AlN и 3C-SiC

The interaction between a+c-type and a-type dislocations in thick (up to 14 µm) semipolar GaN layer grown by hydride vapor phase epitaxy on a 3C SiC/Si(001) template has been detailed investigated by means of transmission electron microscopy. It is shown, that the expansion of a dislocation half loop with Burgers vector b=1/3<1-210> during cooling process can be blocked by its reaction with a threading dislocation with b=1/3<1-210> to form a dislocation segment with b=<0001>. This dislocation reaction is discussed in terms of the energy relaxation. The approximation estimate made within the linear tension approach gives the total energy gain ~7.6 eV/Å (that is, in general, ~45.6 keV for the observed screw dislocation segment of length 600 nm formed as a result of the reaction). Using the core energy calculations, the dislocation core contribution was also estimated as ~19.1 keV.

ON ONE APPROXIMATION ESTIMATE

Linear operators satisfying some conditions are considered. The given operators are a particular kind of class operators (by P.P. Korovkin). For the estimate derivation the interpolation method is used, described in the works by Yu.G. Abakumov and O.N. Shestakova

The estimated store of soluble salts in the Lake Eyre catchment in Queensland and their possible transport in streamflow to the lake

Analytical data from 145 samples of deeply weathered and unweathered rocks and 35 soil samples form the basis for a first approximation estimate of the store of soluble salts in the Lake Eyre catchment covering about 500 x 103 km2 in Queensland. A simple landscape model is defined to estimate the spatial distribution of the soluble chemical constituents of the various rocks and soils. The estimated quantities of soluble sodium and chloride in the catchment are 14x 109 and 25 x 109 tonnes respectively. Some weathered rocks also contain appreciable nitrate and ammonium ions. Available data indicate that bicarbonate, sodium and calcium are the dominant ions in stream flood flows, whereas halite and gypsum are the dominant salts in the lake. Precipitation or reconstitution of degraded clays in the suspended load may account for the absence of carbonates in the lake. It is concluded that the weathered and unweathered Cretaceous sedimentary rocks in the catchment contain large stores of soluble salts, and are the most likely sources of the bulk of the salts in the lake.