We consider a fibre laser system generating ∼10-μJ, ∼500-fs pulses with a peak power of ∼10 MW at a repetition rate of 100 kHz and emission wavelength of 1.56 μm. The system is based on a master ...oscillator - power amplifier configuration. The amplifier ensures chirped-pulse amplification. The pulses are then compressed by a dispersive grating compressor. The output amplifier stage is based on a specially designed tapered large mode area erbium-doped fibre for suppressing nonlinear effects. The experimental data agree with numerical simulation results for the stretcher, amplifier and compressor. The stretcher and amplifier have been simulated using a generalised nonlinear Schrödinger equation. In addition, numerical simulation results suggest that optimising the stretcher and compressor will potentially allow the peak power of the system to be scaled up to ∼30 MW.
In this paper, we consider the need to assess the influence of the parameters of a linear time-invariant causal system in the processing of quadrature amplitude modulation signals of various ...positionality and constellation diagram irregularity. We describe the equations that determine the energy balance of a radio line and the total losses arising in route. We have developed mathematical expressions to assess the equivalent energy losses caused by the irregularity of amplitude-frequency and phase-frequency characteristics of the frequency selection filters. We propose a procedure to assess the non-noise losses in the frequency selection filters when designing high-speed radio systems for transmitting the information.
The purpose of research
is to analyze the functionality of classical and advanced sensors for controlling the mechanical parameters of aircraft using the example of strain and vibration sensors to ...identify their current areas of development.
Methods
. Research methods are based on the concepts of the theory of sensory systems, the theory of diagnostics and forecasting of the technical condition of aircraft. Methods of multi-criteria analysis, parametric and structural synthesis are used. The principles of operation, as well as the functionality of the main classical sensors used in aircraft to control the parameters of deformation and vibration, are analyzed. A critical assessment of the possibilities of using the analyzed sensors for implementation in various tasks of aviation diagnostics of mechanical parameters has been made.
Results
. It has been established that the impact of flight loads on the airframe and critical components of aircraft is accompanied by the appearance of hidden deformations in the form of mechanical stresses, which are divided into two components: normal and tangential. Analytical dependencies are obtained for calculating the above quantities using fiber-optic sensors with distributed Bragg cells that convert the change in their own linear dimensions into a change in the reflected wavelength. A necessary condition for obtaining correct measurement results is the temperature compensation of the cells, which makes it possible to localize the places of deformations with an accuracy up to the location of a particular cell. The practical results of using alternative sensors for detecting hidden deformations (cracks) based on radio frequency identification methods in various frequency ranges are presented.
Conclusion
. The development of the method for diagnosing stress-strain states of aircraft complex units is the use of frequency-Doppler fiber-optic sensors with a high signal-to-noise ratio and a spherical radiation pattern, which will allow developing technical means for monitoring the dynamics of internal deformations of controlled units in real time. As promising areas of research in the field of creating new sensors with new physical properties, fiber-optic Bragg sensors with an inclined grating should be considered.
The purpose of research
is to determine the list of necessary controlled parameters of promising aviation systems, which represent a complex system of interaction "pilot - aircraft - environment", as ...well as to assess the ranges of their change.
Methods
. Research methods are based on the concepts of the theory of diagnostics and prognosis of the technical condition of aircraft, ergonomic systems. Methods of multi-criteria analysis, parametric and structural synthesis are used.
Results
. It is shown that the choice of the range of controlled helicopter units is determined by their purpose, the severity of consequences in case of failure, testability, operating conditions and modes, the predicted level of reliability, as well as the experience of operating prototypes and analogues. A variant of organizing a parallel system for diagnosing and predicting the technical condition of advanced aviation systems has been developed. This article presents a stochastic (probabilistic) diagnostic model of damage to the inter-rotor bearing of an aircraft engine, designed to study the correlation dimension of a vibration signal, which imitates the spectral composition of a real vibration signal, with a different form of amplitude distribution density. A decisive rule for predicting engine failure 8-9 flights before the destruction of the inter-rotor bearing is presented.
Conclusion
. For objective control of the parameters of units of heavy and light helicopters, they are divided into 10 groups, for each of which the composition of diagnostic control sensors is determined based on an analysis of the necessary and sufficient values of the parameters in real time. The range of measurements of specific physical quantities is assigned at the stage of designing one or another vital system of the aircraft. Limits of measurement of parameters are set during regular measurements, as well as at the stages of verification and testing of state control. A variant of the formation of a boundary separating a good and a faulty state, described by a hypersurface, is presented.
We have demonstrated a femtosecond erbium-doped fibre laser system built in the master oscillator/power amplifier (MOPA) approach. The final amplifier stage utilises a specially designed large mode ...area active fibre cladding-pumped by multimode laser diodes. The system is capable of generating submicrojoule pulses at a wavelength near . We have obtained pulses with an energy of . The output of the system can be converted to wavelengths shorter than through the generation of dispersive waves in passive nonlinear fibre. We have obtained ultra-short pulses with a spectral width of and a centre wavelength of , which can be used as a seed signal in parametric amplifiers in designing petawatt laser systems.
A description of a COSMOS laboratory facility for the controlled motion simulation of microsatellites created in Keldysh Institute of Applied Mathematics of the Russian Academy of Sciences and the ...results of its application to the simulation of the control algorithms are presented. The laboratory facility consists of an aerodynamic table and microsatellite mock-ups. Due to the air cushion between the table surface and the disks on which the mock-ups are installed, free motion with three degrees of freedom becomes possible: two translational and one rotational. A review of the simulator’s international analogues has revealed its advantages and disadvantages. A motion determination algorithm based on video processing is described and its accuracy is studied. The results of the investigation of perturbations acting on the mock-ups on the aerodynamic table are presented. The performance of the control algorithms is demonstrated.
New diagnostic methods are being sought for ovarian cancer due to its higher prevalence, which is the result of an increase in the share of elderly women. The purpose of this study was to analyze the ...content and sensitivity of immunoglobulins and the phagocytic activity of peripheral blood in order to improve the diagnostics of ovarian cancer among elderly women. The phagocytic activity and the immunoglobulin level in the peripheral blood were assessed with immunological and spectrophotometric methods in 78 patients with ovarian cancer aged 65–70 years. The control group comprised 42 women of the same age with no ovarian cancer. The primary importance of circulating immune complexes and the indices of neutrophil activity and the inhibition of phagocyte migration was established for laboratory diagnostics of ovarian cancer among elderly people. The use of highly informative parameters of systemic immunity may enhance the diagnostics of ovarian cancer in the elderly.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Due to the increase in the proportion of elderly women, the prevalence of ovarian cancer is increasing, which requires the search for new methods of its diagnosis. The aim of the work is to analyze ...the content and informativeness of immunoglobulins and phagocytic activity of peripheral blood to improve the diagnosis of ovarian cancer among elderly women. In 78 patients with ovarian cancer aged 65-70 years immunological and spectrophotometric methods studied phagocytic activity and the level of peripheral blood immunoglobulins. 42 women of the same age with no ovarian cancer served as control. The primary importance of circulating immune complexes, phagocyte migration inhibition index and neutrophil activity index for laboratory diagnosis of ovarian cancer among the elderly was established. The use of highly informative parameters of systemic immunity improves the diagnosis of ovarian cancer in the elderly.
The purpose of research
The aim of the study is to estimate the maximum transmission range of video information of various quality from an unmanned aerial vehicle to predict its capabilities when ...monitoring an emergency situation.
Methods.
Research methods are based on the concepts of the theory of radio electronics, the theory of diagnostics and prognostics of the technical condition of unmanned aerial vehicles. The methods of multicriteria analysis, parametric and structural synthesis were used. The principles of transmitting video information from unmanned aerial vehicles used to monitor emergency situations are analyzed. A critical assessment of the maximum transmission range of video information from unmanned aerial vehicles during emergency monitoring has been made.
Results.
Graphs of the dependence of the energy reserve in the radio communication line between the unmanned aerial vehicle and the ground control system have been obtained, allowing to estimate the maximum values of the transmission range of video information of various quality in the 2.4 and 5.8 GHz bands when monitoring emergencies. The maximum line-of-sight range between the UAV and the UAV slightly depends on the lifting height of the antenna of the mobile UAV and at the lifting height of the UAV from 100 to 500 m is from 40 to 85 km. The maximum range of HD quality video transmission with the FM-4 UAV using Turbo 7/8 turbocoding in the 2.4 and 5.8 GHz bands is 3 and 7 km, respectively, and when transmitting FHD quality video information with the CAM-16 UAV using Turbo 7/8 turbocoding in the 2.4 and 5.8 GHz bands is 1.4 and 3.3 km.
Conclusion.
The development of a method for determining the maximum transmission distance of video and command-telemetry information allows for a more accurate assessment of the energy reserve in the radio communication line with an unmanned aerial vehicle. Unmanned aerial vehicles for direction finding and detection of rescue beacons of victims during search and rescue operations should be considered as promising areas of research in the field of the use of unmanned aerial vehicles in emergency situations.
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