Nonlinear decoupling sliding mode control and attitude control ofspacecraft

Control of a class of uncertain nonlinear systems which can be decoupled by state-variable feedback is considered. A variable-structure-control (VSC) law is derived so that in the closed-loop system the output variables asymptotically track given output trajectories in spite of any uncertainty in the system. On the basis of this result, a control law is derived for the attitude control of an orbiting spacecraft in the presence of uncertainty using reaction jets. The controlled outputs are the three Euler angles which describe the orientation of the spacecraft relative to an orbital frame. Simulation results are presented to show that, in the closed-loop system, precise attitude control is accomplished in spite of the uncertainty in the system     

Unsteady oscillation of a deformable airfoil section in incompressible flow

The unsteady aerodynamic loads (pressure increment and generalized forces) acting on a deformable thin airfoil section are determined for its arbitrary motion in the incompressible flow with transverse gusts. In this case, the exact Küssner solution in series is used for harmonic oscillation of an airfoil, in which the Theodorsen function is approximated by a sum of fractional functions with poles. In the time domain, these functions are replaced by the unknown functions that satisfy the one-type ordinary first order differential equations. The equations obtained are combined with the differential equations of the airfoil motion in the generalized coordinates and are used for analyzing the aeroelastic system stability and calculating its dynamic response to gust loads.     

A Problem of choosing an optimal number of information unmanned aerial vehicles

Using formalism of the queueing theory, we propose two-objective models for optimizing the number of unmanned aerial vehicles (UAV) designed for remote monitoring (reconnaissance) of certain regions. A model that takes into account the UAV failure in performing a flight mission is considered. The numerical method and examples of solving problems stated are presented.     

Thermodynamic features of aircraft diagonal gas turbines

An effect of the Coriolis forces on the process of gas expansion in the turbine stage is considered. Expressions for efficiency with regard for the radial flow passage are derived. The calculation results and statistical data on the geometric parameters of diagonal stages are presented.     

Investigation of direct integration for nonlinear finite element equations of motion by the modified central difference method

The investigation of stability and precision of the previously proposed implicit scheme of direct integration for the finite element equations of motion is presented. The scheme parameter values that ensure its unconditional stability in the nonlinear problems are determined and comparison with existing procedures is given.     

On the variabilities of the Total Electron Content (TEC) over the Indian low latitude sector

The Total Electron Content (TEC) from four locations in the Indian sector namely, Trivandrum (8.47°N, 76.91°E, Geomag.0.63°S, 0.3° dip), Waltair (17.7° N, 83.3°E, Geomag. 6.4°N, 20° dip), Bhopal (23.28°N, 77.34°E, Geomag.14.26°N, 33.2° dip), and Delhi (28.58°N, 77.21°E, Geomag.19.2°N, 43.4° dip) during a low sunspot year of 2004 are used to study the variabilities of the TEC. The day time TEC values are higher over Waltair and Bhopal compared to those at Trivandrum and Delhi. Considerable day-to-day variations in the diurnal values of TEC are observed at the anomaly crest locations. The observed GPS-TEC has been compared with the IRI-2007 model derived TEC considering three different options (IRI-2001, IRI-2001 corrected and Ne-Quick) available in the model for the topside electron density. The TEC derived with Ne-Quick and IRI-01 corrected options show better agreement with GPS-TEC while the TEC from IRI-01 method shows larger deviations. From the correlation analysis carried out between TEC value at 1300 h LT and solar indices parameters namely sunspot number (SSN), F10.7 and EUV, it is observed that the correlation is more during equinoctial months and less during summer months. The correlation coefficients observed over the anomaly locations, Bhopal and Delhi are lower compared to those at Trivandrum and Waltair.     

SVSS: Intelligent video surveillance system for aircraft

Safety and security are the most discussed topics in the aviation field. The latest security initiatives in the field of aviation propose [1I] the aircraft carriers to implement video surveillance within the aircraft at strategic locations. The current proposals allow the video surveillance data to be stored within the aircraft and monitored by one of the flight crew. The monitoring crew will be responsible for identifying the anomaly within the aircraft and take necessary preventive actions. With the introduction of additional technology within the aircraft, mere human perception may not be sufficient to make a decision. In this research work, the authors explore the possibility of implementing a smart video surveillance system (SVSS) within the aircraft that is tuned toward detecting the behavioral anomaly within the aircraft. The SVSS will generate security triggers when it detects an anomaly within the aircraft. These triggers could be combined with other triggers generated by different aircraft components (possible alarms from the flight crew, data traffic anomaly, or alarm generated by one of the avionics components) to provide a better understanding of the situation to the monitoring crew.     

Aircraft health management network: A user interface

Network management is one of the most discussed topics in the networking fraternity. The efficiency of the network management suit is measured by the number of parameters/components handled by the application while making decisions. In the case of internet-enabled aircrafts, along with network security, even aircraft safety needs to be considered as a factor while designing the Network Management suit. This requires the Network Management suit to monitor/analyze the aircraft-related data (avionics data, physical security parameters, etc.) while determining the proper functioning of the overall system. Herein, these authors present a framework for Network Management suit that, along with network health, monitors inputs from avionics, video surveillance system, weather monitoring system, and manual pilot alarms, and based on the situation, reconfigures the on-board networking devices to stream appropriate flight-critical data to the ground station. The proposed framework attempts to provide a comprehensive user interface for the flight health monitoring crew with all relevant data.     

Spectrophotometric diagnostics of energy characteristics and conductance of the auroral ionosphere from satellite: 1. Specific methods,accuracy problems,and instrumentation requirements

One of the most important tasks of space research is to find a way of real-time monitoring of the space environment conditions around the Earth. This is necessary in order to provide warning about the threats of critical failures in ground-based and space technological systems, thus providing for their stable and secure operation. In view of this concern, methods of diagnostics of ionospheric energy and electrodynamic characteristics continue to be developed on the basis of spectral and photometric measurements, analyzing the glow intensity of emissions of the upper atmosphere observed from above. Serial panoramic monochromatic maps of the intensity of luminosity of the upper atmosphere emissions measured from orbiting detectors can serve as a main data source for such an analysis. In this paper we consider the principal aspects of the method, and, on this basis, the instrumentation requirements are formulated.