Andris Vaivads, Jevgēnijs Tereščenko and Vladimirs Šestakovs
The article presents a semiotic model of “aircraft conditions” in flight and multilevel structures of an aircraft. The hierarchical structure of abstract models is divided into blocks and levels that make them more compact by applying a mathematical apparatus corresponding to the goals sated. The above models were tested on the basis of statistical data on TU-154 aircraft failures for 10 years. Various aircraft functional system failures in flight were examined. The state of the aircraft is identified by normative indicators recorded in the “Aircraft Technical Operation Manual”.
This paper deals with the problem of optimal resource distribution in optimal way among the units of an aviation company. This task could be solved by using the method of dynamic programming. Using Mathcad 14 programming language, there was created a special program that allows to make corresponding calculations. The solution of the real task for an aviation company is observed in this paper as a numerical sample of limited resource distribution between the units of the company in order to get the maximum profit.
Ruta Bogdane, Aleksandrs Bitiņš, Vladimirs Šestakovs and Yasaratne Bandara Dissanayake
In this article, the authors offer a methodology for determining the quality of airline performance by taking into account the level of flight safety on the basis of factor analysis and the results of methodology approbation in the conditions of a functioning airline. The assessment of the level of airline performance quality taking into account the level of flight safety within a certain time span is rather sensitive, informative and reliable. They allow us to detect those changes in industrial and economic conditions and factors that are related to a certain degree of potential deterioration of flight safety. This creates conditions for revealing the tendencies towards the deterioration of flight safety at the stage of their origin, when they have not yet caused deep, irreversible changes in the flight safety of an airline.
Aleksandrs Urbahs, Konstantīns Savkovs, Gints Rijkuris and Darja Andrejeva
Corrosion is one of the most common naturally occurring processes studied by thermodynamics, which includes oxidation process, metal disruption, and its chemical and electrochemical effects under environmental influence. Corrosion of metal and equipment accounts for a considerable proportion of total corrosion losses, thus providing the impetus for further investigation and developments related to corrosion protection in order to provide transport systems and industry with corrosion preventive materials and tools.
Volodymir Kharchenko, Andrii Grekhov, Vasyl Kondratiuk and Karina Nagorna
Original models of “Aircraft-Satellite-Ground Station” communication channel based on IEEE 802.16 standard were built by using MATLAB Simulink. The influence of aircraft transmitter nonlinearity for different types of fading in the channel (Rayleigh and Rician) was studied and the possibility of correcting nonlinearity by using pre-distortion was revealed. The impact of space-time diversity (MISO 2 × 1) for different types of fading in channels was investigated. The effect of the Doppler frequency shift on the operation of communication channels was analyzed.
Aleksandrs Urbahs, Margarita Urbaha and Kristīne Carjova
The aim of this research is to develop a vertical rotation axis variable geometry wind turbine (WT). The experimental prototype is being manufactured with the help of CAM (Computer-aided manufacturing) technologies – computer-based preparation of the product manufacturing process. The Institute of Aeronautics of Riga Technical University is using CNC (Computer Numerical Control) machines for manufacturing the innovative WT and its components. The aerodynamic research has been done in T-4 wind tunnel at an air flow rate from 5 m/s to 30 m/s. The power increase of the variable geometry WT is a topical issue. Installation of such WTs in wind farms is possible and is subject to further research.
The rotating stall inception data analysis using Analytic Wavelet Transform (AWT) in a low-speed axial compressor was presented in the authors’ previous studies , . These studies focused on the detection of instability inception in an axial flow compressor when it enters into the instability regime due to the modal type of stall perturbation. In this paper, the effectiveness of AWT is further studied by applying it under different testing conditions. In order to examine the results of AWT on highly sampled data, at first, the stall data were acquired at a high sampling frequency and the results were compared with the conventional filtered signals. Secondly, the AWT analysis of stall data was carried out for the condition when compressor experienced a spike type rotating stall disturbance. The stall inception information obtained from the AWT analysis was then compared with the commonly used stall detection techniques. The results show that AWT is equally beneficial for the diagnostic of compressor instability regardless of the data sampling rate and represents an outstanding ability to detect stall disturbance irrespective of the type of stall precursor, i.e. the modal wave or spike.
Sigurdur Hrafn Gislason, Ruta Bogdane and Inese Vasiļevska-Nesbita
A Fatigue Monitoring Tool (FMT) model was constructed for an operational airline in order to manage the fatigue levels of their crews in accordance with Fatigue Risk Management System (FRMS) practices. This article describes the implementation of the Fatigue Monitoring Tool model and the airline’s aims to put the recent scientific findings on aviation fatigue into practical use. The model consists of proxy points allotted to various duties and rest periods.
Vasyl Kondratiuk, Eduard Kovalevskiy and Svitlana Ilnytska
Global satellite navigation system (GNSS) is by far the most cost-effective outdoor positioning technology currently available and used for many types of applications. In some cases a user may face difficult conditions, like restricted access to the navigation satellites due to natural or man-made phenomena. This paper presents an idea of an integrated positioning system capable of functioning under limited visibility conditions of navigation satellites. The system includes a digital antenna array, channels for converting radio navigation signals, a phase difference meter, a gyro platform with 3 gyros, an altimeter and a special calculator. With the help of mathematical modeling, the accuracy characteristics of the system are investigated by determining the coordinates of the carrier under conditions of a small number of available satellite signals.
Aleksandrs Urbahs, Sudip Das, Shravan Koundinya Vutukuru and Kristīne Carjova
Experiments and computational studies were carried out to get an understanding of the flow field around a rectangular supersonic intake with pointed cowl shape. Experiments include quantitative pressure measurements and flow visualization studies by using schlieren techniques. The effects of the presence of various cowl shapes on ramp surface have been obtained computationally at Mach 2.0. The experiments were carried out only for the pointed cowl. Schlieren Photographs were taken. Three-Dimensional simulations were made by using FLUENT at supersonic speed. The details of the experiments and computations are discussed.