Wyniki wyszukiwania - BazTech

1

Influence of flight control law on spin dynamics of aerodynamically asymmetric aircraft

Malik B., Akhtar S., Masood J.

Journal of Theoretical and Applied Mechanics

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2017

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Vol. 55 nr 3

963—975

EN

In this paper, we analyze the spin dynamics of an aerodynamically asymmetric aircraft in open-loop configuration and also evaluate the performance of gain scheduled flight control law in improving dynamic characteristics of aircraft spin. A look-up tables based aerodynamic model is developed from static, coning and oscillatory coning rotary balance wind tunnel test data. As a starting point, all possible steady spin modes are identified by solving the aircraft dynamic model comprising moment equations. The influence of high-alpha yawing moment asymmetry on predicted right and left spin modes is discussed. Six degree of freedom simulations of left and right flat spins are performed in open-loop and closed-loop configurations with the flight control law. Our studies reveal that large amplitude oscillations in the angle of attack and sideslip observed in the open-loop configuration are significantly damped by the control law. The control law reduces the recovery time of the left flat spin. However, the aircraft natural tendency to rotate rightwards due to yawing moment asymmetry at high angles of attack renders flight control law ineffective in aiding the recovery of the right flat spin.

2

Comparative analysis of buckling load of circular and corrugated tubes by utilizing key performance indicators

Rahim M. R., Akhtar S., Bharti P. K.

International Journal of Applied Mechanics and Engineering

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2017

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Vol. 22, no. 3

789--797

EN

The performance of buckling load of tubular structures under quasi-static axial loading is quite appreciable, numerous tubes of various cross-section have been extensively investigated and corrugated sections have been designed to further improve the performance. In this paper, a carefully designed set of key performance indicators (KPIs) is utilized to assess and compare the buckling load of circular and corrugated tubes. A series of diagrams related to KPIs with various parameters of tubes are presented to demonstrate the influence of sectional configuration on the performance of tubes as well as the effect of the material on the potential of the same. The work is inestimable to engineering designs and applications, and further studies on the buckling load of other configurations.

3

Connectivity based technique for localization of nodes in wireless sensor networks

Farooq-I-Azam M., Ayyaz M. N., Akhtar S.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 5

171-175

EN

We propose a localization algorithm for wireless sensor networks, which is simple in design, does not involve significant overhead and yet provides acceptable position estimates of sensor nodes. The algorithm uses settled nodes as beacon nodes so as to increase the number of beacon nodes. The algorithm is range free and does not need any additional piece of hardware for ranging. It also does not involve any significant communication overhead for localization. The simulation and results show that good localization accuracy is achieved for outdoor environments.

PL

W artykule opisano algorytm lokalizacji dla sieci czujników bezprzewodowych, cechujący się niskimi kosztami ogólnymi implementacji i odpowiednią dokładność estymacji pozycji. W metodzie wykorzystane są węzły osadzone jako węzły sieci. Algorytm nie ma ograniczeń zasięgowych i nie wymaga dodatkowego sprzętu do szacowania odległości. Wyniki badań symulacyjnych potwierdziły dobrą dokładność lokalizacji w środowisku zewnętrznym.