Cellular-Connected UAV with Adaptive Air-to-Ground Interference Cancellation and Trajectory Optimization

This letter studies a cellular-connected unmanned aerial vehicle (UAV) scenario, in which a UAV user communicates with ground base stations (GBSs) in cellular uplink by sharing the spectrum with ground users (GUs). To deal with the severe air-to-ground (A2G) co-channel interference, we consider an adaptive interference cancellation (IC) approach, in which each GBS can decode the GU's messages by adaptively switching between the modes of IC (i.e., precanceling the UAV's resultant interference) and treating interference as noise (TIN). By designing the GBSs' decoding modes, jointly with the wireless resource allocation and the UAV's trajectory control, we maximize the UAV's data-rate throughput over a finite mission period, while ensuring the minimum data-rate requirements at individual GUs. We propose an efficient algorithm to solve the throughput maximization problem by using the techniques of alternating optimization and successive convex approximation (SCA). Numerical results show that our proposed design significantly improves the UAV's throughput as compared to the benchmark schemes without the adaptive IC and/or trajectory optimization.Comment: Technical Repor

Ignition and Combustion Characterization of Nano-Al-AP and Nano-Al-CuO-AP Micro-sized Composites Produced by Electrospray Technique

AbstractMetal powders such as aluminum nanoparticles (Al NPs) have been found huge potential as reactive additives to highly increase energy density in various energetic systems such as propellants, explosives and pyrotechnics. However, it is suffering issues of agglomeration and post-combustion aggregates, which largely reduce the energy utilization efficiency and the energy release rate. One option to eliminate this disadvantage is to coat the nanoparticles with gas generator which can produce gas to prevent the sintering. This work use electrospray technique to assemble Al NPs and Al-CuO NPs into microparticles, with coating of gas generator-ammonium perchlorate (AP) to produce gas to prevent possible sintering, thus obtaining a highly reactive Al-based composites. The Al/CuO NPs composites are ignited in a confined cell to measure its combustion pressure history. The peak pressure and the pressurization rate of Al/CuO/AP is more than 3X higher and faster, compared to the physically mixed Al/CuO nanothermite. This work provides an ideal approach to prepare Al NPs based energetic materials such as solid propellant or solid fuel air explosives

Dynamic Coupling Analysis of E-type Membrane for Six-Axis Force Sensor

The E-type membrane which is used for measuring forces in other five directions will generate coupling outputs and influence accuracy of the sensor, when six-axis force sensor based on double layer E-type membrane is under dynamic loads in MZ direction. In terms of the fundamental theory of mechanical vibration, vibration mechanics and elastic mechanics, this paper simplifies the E-type membrane into a straight circular shaft with constant section and works out the coupling outputs under the condition of dynamic loads. It provides theoretical basis for dynamic decoupling of six-axis force sensor

Static Experimental Study on Flame Retardant and Explosion Suppression Performances of Fire Resistant Diesel Fuel

AbstractTo assess the flame retardant and explosion suppression performances of fire resistant diesel fuel, static experiments with ordinary diesel fuel (Diesel fuel 1, D1 for short) and fire resistant diesel fuel (Diesel fuel 2, D2 for short) detonated by explosives were performed in this study. The explosion process and surface temperature of the fireballs were recorded using a high-speed camera and an infrared thermal imager. Meanwhile, the overpressures of the explosion shock waves of the two diesels were also recorded using pressure sensors embedded in the ground. The experimental results show that the diesel fuels are dispersed and ignited to produce explosion fireball when explosive is detonated in fuel tank. At the same time, part of diesel fuel produces pool fire on the ground. The pool fire of D1 lasts about 3000ms, while D2 lasting only about 700ms. The maximum temperature and the duration of high temperature of D1 explosion fireball are 1558.8°C and 1392ms respectively, which are 1.11 and 1.29 times those of D2. In the position of 2 m far from the vertical projection point of the explosion center, the overpressure of the explosion shock wave of D1 is 53.30kPa, while that of D2 is 31.60kPa. Moreover, the overpressures of D1 are also higher in the other location of the pressure area. Therefore, it is proved that the explosive power of D2 is significantly lower than that of D1, and the flame retardant and explosion suppression performances of D2 is better than those of D1

Variance-constrained dissipative observer-based control for a class of nonlinear stochastic systems with degraded measurements

The official published version of the article can be obtained from the link below.This paper is concerned with the variance-constrained dissipative control problem for a class of stochastic nonlinear systems with multiple degraded measurements, where the degraded probability for each sensor is governed by an individual random variable satisfying a certain probabilistic distribution over a given interval. The purpose of the problem is to design an observer-based controller such that, for all possible degraded measurements, the closed-loop system is exponentially mean-square stable and strictly dissipative, while the individual steady-state variance is not more than the pre-specified upper bound constraints. A general framework is established so that the required exponential mean-square stability, dissipativity as well as the variance constraints can be easily enforced. A sufficient condition is given for the solvability of the addressed multiobjective control problem, and the desired observer and controller gains are characterized in terms of the solution to a convex optimization problem that can be easily solved by using the semi-definite programming method. Finally, a numerical example is presented to show the effectiveness and applicability of the proposed algorithm.This work was supported in part by the Distinguished Visiting Fellowship of the Royal Academy of Engineering of the UK, the Royal Society of the UK, the GRF HKU 7137/09E, the National Natural Science Foundation of China under Grant 61028008, the International Science and Technology Cooperation Project of China under Grant 2009DFA32050, and the Alexander von Humboldt Foundation of Germany