Secrecy outage probability of a NOMA scheme and impact imperfect channel state information in underlay cooperative cognitive networks

Security performance and the impact of imperfect channel state information (CSI) in underlay cooperative cognitive networks (UCCN) is investigated in this paper. In the proposed scheme, relay R uses non-orthogonal multiple access (NOMA) technology to transfer messages e1, e2 from the source node S to User 1 (U-1) and User 2 (U-2), respectively. An eavesdropper (E) is also proposed to wiretap the messages of U-1 and U-2. The transmission's security performance in the proposed system was analyzed and performed over Rayleigh fading channels. Through numerical analysis, the results showed that the proposed system's secrecy performance became more efficient when the eavesdropper node E was farther away from the source node S and the intermediate cooperative relay R. The secrecy performance of U-1 was also compared to the secrecy performance of U-2. Finally, the simulation results matched the Monte Carlo simulations well.Web of Science203art. no. 89

Implementation of UAV Coordination Based on a Hierarchical Multi-UAV Simulation Platform

In this paper, a hierarchical multi-UAV simulation platform,called XTDrone, is designed for UAV swarms, which is completely open-source 4 . There are six layers in XTDrone: communication, simulator,low-level control, high-level control, coordination, and human interac-tion layers. XTDrone has three advantages. Firstly, the simulation speedcan be adjusted to match the computer performance, based on the lock-step mode. Thus, the simulations can be conducted on a work stationor on a personal laptop, for different purposes. Secondly, a simplifiedsimulator is also developed which enables quick algorithm designing sothat the approximated behavior of UAV swarms can be observed inadvance. Thirdly, XTDrone is based on ROS, Gazebo, and PX4, andhence the codes in simulations can be easily transplanted to embeddedsystems. Note that XTDrone can support various types of multi-UAVmissions, and we provide two important demos in this paper: one is aground-station-based multi-UAV cooperative search, and the other is adistributed UAV formation flight, including consensus-based formationcontrol, task assignment, and obstacle avoidance.Comment: 12 pages, 10 figures. And for the, see https://gitee.com/robin_shaun/XTDron

Spin force and intrinsic spin Hall effect in spintronics systems

We investigate the spin Hall effect (SHE) in a wide class of spin-orbit coupling systems by using spin force picture. We derive the general relation equation between spin force and spin current and show that the longitudinal force component can induce a spin Hall current, from which we reproduce the spin Hall conductivity obtained previously using Kubo's formula. This simple spin force picture gives a clear and intuitive explanation for SHE

Soluble oligomeric Abeta42 affects microglia activation and mitochondrial respiration

Microglia activation is associated with many neurodegenerative diseases such as Alzheimer\u27s disease (AD). When activated, microglia cells change their morphology and become phagocytic. In the Alzheimer\u27s brain, microglia cells play an important role in scavenging plaque-damaged cells and in clearing Abeta plagues. Soluble oligomeric Abeta (oAbeta) is capable to stimulate microglia activation. In AD brain, microglia cells accumulate around senile plaques as a hallmark of the pathology. Recently, we found that mitochondrial oxidative phosphorylation is affected in a dose-dependent manner in a microglia cell line (C8-B4) and primary rat glia cell. Mitochondrial basal, maximal and spare respiration capacities increase at low concentrations of oAbeta and then decline at higher concentrations. Flow cytometry for markers of microglial activation (IBA1 upregulation) similarly shows a low dose increase and a high dose decline. In contrast, the oAbeta stimulation does not alter the mitochondrial oxidative phosphorylation in a mouse hippocampal neuronal cell line (HT22), suggesting a brain cell-specific response to oAbeta. Our experiment results suggest that at low concentrations of oAbeta, which would normally occur in healthy brains, an increased mitochondrial respiration hints that microglia activation responds to mild oAbeta stimulation. In contract, at higher pathological levels of oAbeta, microglial activation and its associated mitochondrial functions are inhibited which may prevent phagocytosis and allow the accumulation of Abeta