Mathematical modeling, theory of random processes, theory of control and decision-making and their applications.The main efforts were aimed at solving the practically important problem of finding the distribution function of the moment of the first output of a vector random process on the selected part of the boundary of a given region in multidimensional space. This problem appears in studying stochastic systems in situations when normal system operation corresponds to a position of a point depicting the system in a certain region of the systems phase space, and consequences of the point leaving this region depend on which part of the regions boundary it will leave through. The scheme is proposed that allows one to find estimates of the probability of events associated with level crossings and level achievements by a non-Markovian smooth random process. The results obtained are used, in particular, in aviation to solve the problem of ensuring the safety of aircraft flight.

He graduated from the Kolmogorov Physics and Mathematics Boarding School No.18 at the Moscow State University, and only with all fives except one four in the certificate. He graduated from the Moscow Institute of Physics and Thechnology, and only with excellent marks in the grade book. In 1986, he entered the full-time postgraduate study at the Computing Center of the Academy of Sciences of the USSR, defending in 1988 a Ph.D. thesis in 01.01.09 specialty - mathematical cybernetics. In the same year, he became the winner of the competition of scientific works of young scientists of the Computing Center of the Academy of Sciences of the USSR. In 1996, he defended his doctoral dissertation at the Computing Center of the Russian Academy of Sciences in the specialty 05.13.18 - theoretical foundations of mathematical modeling, numerical methods and program complexes. In 1998, he was awarded the title of professor in the department of higher mathematics.

The results of this period of scientific activity are collected in the monograph “Outliers of Random Processes: Applications in Aviation”, published in 2005 by the Nauka publishing house, the publication of which was supported by the Department of Mathematical Sciences of the Russian Academy of Sciences. The methods proposed in the monograph and in it software implemented on a computer were used for the probabilistic assessment of the accuracy of landing real aircraft, in particular, ship-based aircraft.

In 2009-2014, he was engaged in the tasks of forecasting and managing sales of goods in retail chains. The results of these studies, supported by the RFBR grant (number 12-01-00906-a), were published in the monograph “Forecasting and Sales Management in Retail Networks”, published by Fizmatlit Publishing House in 2012. The algorithm for introducing discounts on the price of goods proposed in it when actual sales lag behind planned ones, it has been introduced and is used in a large trading network that includes about a thousand stores.

In December 2018, he was invited to make a presentation entitled “Estimating the probability that a random process first reaches the boundary of a region on a given time interval” at the flagship conference of the Control Systems Society (CSS) of the International Institute of Electrical and Electronics Engineers (IEEE) - Conference on Decision and Control (CDC), which is the most representative and most status regular conference on a planetary scale in decision theory and control theory for both deterministic and stochastic systems. The article of the same name was published in the proceedings of the CDC-2018. In December 2019, he was invited to make a presentation entitled “Estimating the probability of safe landing for aircrafts” at the CDC-2019. The article of the same name was published in the proceedings of the CDC-2019.

In 2019, at the initiative of the well-known English publisher Cambridge Scholars Publishing, the monograph "Crossings Problems in Random Processes Theory and Their Applications in Aviation" was published.

1. S. L. Semakov, “The probability of hitting of a level by a component of multidimensional process within prescribed interval under restrictions on the remaining components”, Theory Probab. Appl., 34:2 (1989), 357–361          
2. S. L. Semakov, Outliers of Random Processes: Applications in Aviation, Nauka, Moscow, 2005 , 200 pp. (in Russian)  
3. S. L. Semakov, I. S. Semakov, “Estimating the probability that a random process first reaches the boundary of a region on a given time interval”, Proceedings of the 57th IEEE Conference on Decision and Control (CDC2018) (Miami Beach, Fl, USA, December 17–19, 2018), 2018, 256–261        
4. S. L. Semakov, Crossings problems in random processes theory and their applications in aviation, Cambridge Scholars Publishing, Newcastle, UK, 2019 , 200 pp.
5. S. Semakov and I. Semakov, “Method of calculating the probability of a safe landing for ship-based aircraft”, IEEE Transactions on Aerospace and Electronic Systems, 58:6 (2022), 5425–5442      

• Moscow State Technical University of Civil Aviation
• Dorodnitsyn Computing Centre of the Russian Academy of Sciences, Moscow
• Moscow Aviation Institute (State University)
• Moscow Institute of Physics and Technology (State University), Dolgoprudny, Moscow region
• Moscow Automobile and Road Construction Institute (State University)