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The energy efficiency (EE) for the full-duplex massive multi-input multi-output (MIMO) system is investigated. Given the transmit powers of both the uplink and the downlink, the closed-form solutions of the optimal number of antennas and the maximum EE are achieved in the high regime of the signal-to-noise ratio (SNR). It is shown that the optimal number of antennas and the maximum EE gets larger with the increase in user numbers. To further improve the EE, an optimization algorithm with low complexity is proposed to jointly determine the number of antennas and the transmit powers of both the uplink and the downlink. It is shown that, the proposed algorithm can achieve the system performance very close to the exhaustive search. [ABSTRACT FROM AUTHOR]

Hybrid aircrafts are unique type of aircrafts that combine the hover capability of helicopters with the speed and range of airplanes. In this work, we propose a novel hybrid aircraft based on the fixed-wing airplane and quadrotor structures. A complete mathematical model of the aircraft, in helicopter, transition and airplane flight modes is presented. Furthermore, a nonlinear controller for stabilizing the aircraft at hover is proposed. Finally, simulation results are presented in order to illustrate performances of the proposed controller.

A finite-time-convergent differentiator is presented that is based on singular perturbation technique. The merits of this differentiator exist in three aspects: rapidly finite-time convergence compared with other typical differentiators; no chattering phenomenon; and besides the derivatives of the derivable signals, the generalized derivatives of some classes of signals can be obtained—for example, the generalized derivative of a triangular wave is square wave, etc. The theoretical results are confirmed by computer simulations. [ABSTRACT FROM AUTHOR]

A capillary GC method is described for simultaneously measuring fentanyl and midazolam in human plasma. Plasma was extracted at basic pH with cyclohexane–isopentanol (197:3) with Ro21-2212 added as internal standard and fentanyl derivative as carrier. The drug was back-extracted in H2SO4, and then the extract was made basic and reextracted with hexane. The organic phase was evaporated at 40°C under N2and the residue was dissolved in ethanol. A portion was analyzed on a wide-bore capillary column (10 m × 0.53 mm) of HP-1 (2.65 μm), operated at 255°C with N2as carrier gas and N–P detector. The calibration graph for fentanyl and midazolam was linear within the respective ranges of 0.5–100 and 5–1000 ng/ml with a correlation coefficient of 0.9998. The recovery of fentanyl and midazolam was 99.5 ± 4.5 and 99.9 ± 3.2%. The coefficient of variation within a run and between runs was less than 7%. The detection limit for fentanyl was 0.2 ng/ml plasma, and for midazolam was 0.5 ng/ml plasma. The method was applied to therapeutic drug monitoring and pharmacokinetic studies.