Assylbek Issakhov

• Doctor of Philosophy
• Head of School at Kazakh-British Technical University

We study A-computable numberings for various natural classes of sets. For an arbitrary oracle A≥T0′, an example of an A-computable family S is constructed in which each A-computable numbering of S has a minimal cover, and at the same time, S does not satisfy the sufficient conditions for the existence of minimal covers specified in [Sib. Math. J.,...

This paper presents a numerical simulation of a three-phase flow (water, air, and mud) formed during a dam break. For the connection between all phases, the mathematical model was modified to take into account the non-Newtonian and Newtonian fluids. The equations in the mathematical model are discretized by the finite volume method and the relation...

This work presents a numerical simulation of the distribution of heat sinks generated as a result of cooling generators of nuclear power plants in a natural reservoir. The aim of the work was to assess the thermal effect on the water area of Lake Balkhash, near the city of Ulken, where a site for a nuclear power plant was prepared. To obtain real r...

The paper investigates the existence of universal generalized computable numberings of different families of sets and total functions. It was known that for every set A such that ∅ 0 ≤T A, a finite family S of A-c.e. sets has an A-computable universal numbering if and only if S contains the least set under inclusion. This criterion is not true for...

This paper presents the computational results of heat transfer for a 2D laminar flow with different channel tilts with forward facing step and backward facing step, taking into account buoyancy forces for various bottom wall lengths. The inclination angle influence on the distribution of velocity and temperature is investigated. The validated numer...

The functions of the nasal cavity are very important for maintaining the internal environment of the lungs since the inner walls of the nasal cavity control the temperature and saturation of the inhaled air with water vapor until the nasopharynx is reached. In this paper, three-dimensional computational studies of airflow transport in the models of...

In this paper, a computational study of air pollution in idealization urban canyons road for various temperature regimes was investigated. To solve this problem, the Reynolds-averaged Navier-Stokes (RANS) equations were used. Moreover, different turbulent models were used to close this system of equations. To test the numerical algorithm and the ma...

In this work, a computational simulation of the pollutants spread generated during fuel combustion at Ekibastuz SDPP-1 and their chemical reaction in the atmosphere have been presented. Using the example of a real thermal power plant (Ekibastuz SDPP -1), the dispersion NO, NO2, CO and products NO2, HNO3, CO2 during a chemical reaction with oxygen w...

For an arbitrary set A of natural numbers, we prove the following statements: every finite family of A-computable sets containing a least element under inclusion has an Acomputable universal numbering; every infinite A-computable family of total functions has (up to A-equivalence) either one A-computable Friedberg numbering or infinitely many such...

Whether there exists a computable universal numbering for a computable family is the key question in theory of numberings. In a very general setting, this problem was explored in [Yu. L. Ershov, Theory of Numberings, Handbook of Computability Theory, North-Holland; Amsterdam: Stud. Log. Found. Math., Vol. 140, pp. 473–503, 1999]. For sets A that ar...

We prove a criterion for the existence of a minimal numbering, which is reducible to a given numbering of an arbitrary set. The criterion is used to show that, for any infinite A-computable family F of total functions, where ∅ ′ ≤ T A, the Rogers semilattice RA(F) of A-computable numberings for F contains an ideal without minimal elements.