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The traditional MAC protocol in ad hoc networks includes carrier sensing to judge the busy/idle state of a channel. However, in airborne tactical networks, the results of carrier sensing are usually inaccurate due to the wide distribution of nodes, large communication distance, and high-dynamic network topology, and the carrier sensing causes a large transmission delay and low channel utilization...
Among numerous theory models for describing the parametric array's near-field acoustic characteristics, the KZK equation is the most accurate theoretical model. However, the computation efficiency is low by using the frequency-domain method for the parametric array's sound field. The paper drew ideas from the time-domain method to separate the operator, and calculated the KZK equation's nonlinear...
The parametric array can generate low-frequency, high-directivity beam with small-aperture, and it is widely used in underwater navigation, underwater communication, seafloor sediments detection, sub-bottom physiognomy surveying and mapping. However, the parametric array's conversion efficiency is very low, severely restricting the parametric array's further application. In order to improve the parametric...
Real-time and reliable localization is a prerequisite for autonomously performing high-level tasks with micro aerial vehicles(MAVs). Nowadays, most existing methods use vision system for 6DoF pose estimation, which can not work in degraded visual environments. This paper presents an onboard 6DoF pose estimation method for an indoor MAV in challenging GPS-denied degraded visual environments by using...
This essay studies the breakage of glass curtain due to the fire in a tower building with a CFD (computation fluid dynamics) based simulation package (FDS). The heat release rate of fire is 6MW which determined by the function of the tower. The results shows temperature in vertical direction change a lot. Since the tress generated by temperature difference is the cause of glass breakage, glass size...
Micro-Quadrotor aerial robots have enormous potential applications in the field of near-area surveillance and exploration in military and commercial applications. However, stabilizing and position control of the robot are difficult tasks because of the nonlinear dynamic behavior and model uncertainties. Backstepping is a widely used control law for under-actuated systems including quadrotor. But general...
Micro Vertical Take-off and Landing (VTOL) systems represent a useful class of flying robots because of their strong capabilities for small-area monitoring and building exploration. In this paper, we describe a small quadrotor flying robot for the use of indoor autonomous navigation and exploration. Three-level hardware architecture is developed and a fusion of different sensors is implemented, which...
Fuzzy controllers are used in many applications because of their rapid design by translating heuristic knowledge, robustness against perturbations, and smoothness in the control action. It is known that as the number of membership functions increases fuzzy control becomes smoother. However, since the number of rules is an exponential function of the number of inputs and number of membership function,...
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