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We consider a temperature control problem based on the heat equation with a convective term and a quadratic quality functional. We examine the structure of the set of attainable functions and establish controllability of the problem on various sets of admissible controls.

We study the behavior of singular solutions of the Emden-Fowler type equation y(n) = p(x, y, y’,..., y(n-1)|y|k sgn y, n > 2, with a regular (k > 1) or singular (0 1) or a solution that vanishes together with derivatives of order < n at some point or has a point of accumulation of zeros (for 0 < k < 1).

We consider a control problem for one-dimensional heat equation with quadratic cost functional. We prove the existence and uniqueness of a control function from a prescribed set, and study the structure of the set of accessible temperature functions. We also prove the dense controllability of the problem for some set of control functions.

We propose an asymptotic classification for solutions of the equation yIV(x) − po|y|k sgn y = 0, 0 0, and establish the existence of its periodic solutions.

We present results on the existence of oscillating solutions of specific form (“quasiperiodic solutions) for a nonlinear differential equation with power nonlinearity. For oscillating solutions to third-order equations of this type, we obtain an asymptotics of extremums, which is expressed through the asymptotics of extremums of a “quasiperiodic” solution. These results clarify the asymptotic formulas for the modules of extremums of solutions obtained by the author earlier.

For higher-order Emden–Fowler type equations with regular nonlinearity, the asymptotic behavior of their blow-up solutions is investigated. It is proved that for weakly superlinear differential equations, all such solutions have power-law asymptotic behavior.

We study the problem of control over the temperature conditions in industrial hothouses. We consider a model based on the one-dimensional parabolic equation on a bounded interval with quadratic cost functional, prove the existence and the uniqueness of a control function from a prescribed set, and study the structure of the set of accessible temperature functions.

The asymptotic behavior of all solutions to the fourth-order Emden– Fowler type differential equation with singular nonlinearity is investigated. The equation is transformed into a system on the three-dimensional sphere. By investigation of the asymptotic behavior of all possible trajectories of this system an asymptotic classification of all solutions to the equation is obtained.

For the equation $$\displaystyle{ y^{(n)} + p_{ 0}\,\vert y\vert ^{k}\ \mathrm{sign}\,y = 0, }$$ in the cases n = 3, 4, p0 > 0 or p0 1 and singular nonlinearity 0 < k < 1 asymptotic classification of all solutions are given.