Generalized algorithm for determining AES orbit parameters based on quadratic functionals.

The questions of development a generalized algorithm for determining the parameters of the low circular orbit (LCO) of an Earth satellite (ES) based on the use of quadratic functionals are in the focus of this paper. The functionals represent the square of the differences between the measured values of the ES sighting angles and the frequency of the received signal with the values of the same parameters obtained for the assumed values of the Keplerian orbital elements in accordance with the adopted model of the ES motion. Estimates of the orbit parameters are formed from the condition of the minimum of the proposed quality functionals. The proposed algorithm is aimed at the developing two equations for the relationship between the measured values of the azimuth and elevation angles, as well as the frequency of the received satellite signal and the parameters of the satellite orbit. The use of the indicated constraint equations makes it possible to pass from the six-dimensional space of the Keplerian orbital elements to the four-dimensional space of the Keplerian orbital elements when constructing the algorithm and choosing the initial approximations of the orbit parameters. Such a reduction in the dimension of space makes it possible to significantly reduce the amount of computational expenditure, which ensures the stability of the algorithm and expands the possibilities of its practical use with limited resources (computing power and restrictions on the permissible processing time). The following Keplerian orbital elements are proposed as four basic parameters: eccentricity, ascending node longitude, orbital inclination, and perigee argument. The other two elements, the semi-major axis of the orbit and the mean anomaly, are expressed as functions of four basic parameters. This choice is determined by the fact that, in the case of LCO, the pivoting of the initial values of the eccentricity and the argument of perigee is quite simple, which makes it possible to ensure convergence to the exact values of the orbit parameters in a wide value of the initial approximations. Within the Keplerian approximation of the satellite's orbital motion, mathematical relations are presented that determine the operations performed within the framework of the considered algorithm. However, a more complete consideration of the factors influencing the motion of the satellite only leads to more volumetric relations, but does not fundamentally affect the construction of the algorithm itself.

$ \Gamma $-convergence of quadratic functionals with non uniformly elliptic conductivity matrices

<p style='text-indent:20px;'>We investigate the homogenization through <inline-formula><tex-math id="M2">\begin{document}$ \Gamma $\end{document}</tex-math></inline-formula>-convergence for the <inline-formula><tex-math id="M3">\begin{document}$ L^2({\Omega}) $\end{document}</tex-math></inline-formula>-weak topology of the conductivity functional with a zero-order term where the matrix-valued conductivity is assumed to be non strongly elliptic. Under proper assumptions, we show that the homogenized matrix <inline-formula><tex-math id="M4">\begin{document}$ A^\ast $\end{document}</tex-math></inline-formula> is provided by the classical homogenization formula. We also give algebraic conditions for two and three dimensional <inline-formula><tex-math id="M5">\begin{document}$ 1 $\end{document}</tex-math></inline-formula>-periodic rank-one laminates such that the homogenization result holds. For this class of laminates, an explicit expression of <inline-formula><tex-math id="M6">\begin{document}$ A^\ast $\end{document}</tex-math></inline-formula> is provided which is a generalization of the classical laminate formula. We construct a two-dimensional counter-example which shows an anomalous asymptotic behaviour of the conductivity functional.</p>

Rate optimal estimation of quadratic functionals in inverse problems with partially unknown operator and application to testing problems

We consider the estimation of quadratic functionals in a Gaussian sequence model where the eigenvalues are supposed to be unknown and accessible through noisy observations only. Imposing smoothness assumptions both on the signal and the sequence of eigenvalues, we develop a minimax theory for this problem. We propose a truncated series estimator and show that it attains the optimal rate of convergence if the truncation parameter is chosen appropriately. Consequences for testing problems in inverse problems are equally discussed: in particular, the minimax rates of testing for signal detection and goodness-of-fit testing are derived.

Замедляющая система двойная сдвинутая импедансная гребенка"

Using the partial domain method, surface integral equations are obtained for slow-wave systems of double shifted combs taking dissipation on all metal surfaces into account. The case of aliquot comb periods is considered. The quadratic functionals are proposed as dispersion equations. A method to solve complex dispersion equations in the form of functionals for complex constants of propagation is proposed by means of their joint iterations with integral equations. The results of calculating the dispersion with allowance for dissipation in several structures considered are presented.

Shape optimizationviaa levelset and a Gauss-Newton method

In the context of shape optimization via level-set methods, we propose a general framework for a Gauss-Newton method to optimize quadratic functionals. Our approach provides a natural extension of the shape derivative as a vector field defined in the whole working domain. We implement and discuss this method in two cases: first a least-square error minimization reminiscent of the Electrical Impedance Tomography problem, and second the compliance problem with volume constraints.