Securing UAV Communications Via Trajectory Optimization

Unmanned aerial vehicle (UAV) communications has drawn significant interest recently due to many advantages such as low cost, high mobility, and on-demand deployment. This paper addresses the issue of physical-layer security in a UAV communication system, where a UAV sends confidential information to a legitimate receiver in the presence of a potential eavesdropper which are both on the ground. We aim to maximize the secrecy rate of the system by jointly optimizing the UAV's trajectory and transmit power over a finite horizon. In contrast to the existing literature on wireless security with static nodes, we exploit the mobility of the UAV in this paper to enhance the secrecy rate via a new trajectory design. Although the formulated problem is non-convex and challenging to solve, we propose an iterative algorithm to solve the problem efficiently, based on the block coordinate descent and successive convex optimization methods. Specifically, the UAV's transmit power and trajectory are each optimized with the other fixed in an alternating manner until convergence. Numerical results show that the proposed algorithm significantly improves the secrecy rate of the UAV communication system, as compared to benchmark schemes without transmit power control or trajectory optimization.Comment: Accepted by IEEE GLOBECOM 201

Study on Seismic Dynamic Response of Shallow-Buried Subway Station Structure and Ancillary Facilities

Strong earthquakes can cause damages to structural members and also yield non-negligible damages to nonstructural facilities, the latter being closely related to earthquake-induced inertial forces. At present, the acceleration response regularity of shallow-buried subway station structure is not very clear. Using the finite-element software ABAQUS, a dynamic soil-structure interaction model for a two-story subway station structure is established. The distribution of the peak acceleration response of the structure is obtained, and the damage assessment of non-structural facilities is carried out based on the structural acceleration response. The results demonstrate that, in general, the peak acceleration responses of the subway station structure increase from lower to upper story levels, while the peak acceleration responses at the same height are practically equal. Moreover, the peak accelerations of a shallow-buried subway station structure are generally less than or close to the peak ground acceleration. Furthermore, the nonstructural facilities are slightly damaged when subjected to a peak bedrock input acceleration of 0.1 g, and moderately damaged under a peak bedrock input acceleration in the range 0.2 – 0.6 g. Based on the acceleration response characteristics, it is proposed that the peak surface acceleration can be used as an index to evaluate the damage of non-structural facilities in shallow-buried subway station structure, which is simple, practical and basically meets the precision requirements

Strategy, resource orchestration and e-commerce enabled social innovation in rural China

E-commerce enabled social innovation is becoming increasingly important as a way of reducing poverty in developing countries and yet has not been studied much by the IS community. We utilize the concept of resource orchestration as a theoretical lens to develop a fit model that explicates how resources are orchestrated under the guidance of either an indigenous, exogenous or collaborative strategy to achieve e-commerce enabled social innovation. The findings show how resources are orchestrated through the following specific resource-focused actions (collaborating, linking and enriching), which are influenced by the types of strategies applied. Our study also identifies different resource portfolios that influence the type of e-commerce enabled social innovation that can be achieved. This research benefits both academics and practitioners by contributing to cumulative theoretical developments related to e-commerce enabled social innovation and the resource orchestration perspective, and by offering corresponding practical insights to achieve fit between strategy, resource orchestration and social innovation

Refining Sea Urchin Developmental Gene Regulatory Network Models by Incorporating Wnt Signaling and Information Processed at the hox11/13b Locus

The availability of advanced GRN models for sea urchin development presents a unique opportunity to address the function of signaling interactions in cell fate specification at a system-wide level. Here we take a global approach to investigate the regulatory functions of the Wnt signaling system during pre-gastrular development. We examine the embryonic specification processes in order to determine in which embryonic lineages and at what time specific Wnt signals are required. We show a functional divergence among individual Wnt ligands despite their similar and partially overlapped spatial expression. By studying TF activators, we show that expression of wnt genes is tightly controlled and is correlated with their respective functions. In particular Wnt1 and Wnt16, which regulate endodermal specification, are activated by the endoderm regulator Hox11/13b. Motivated by these results and in an effort to further enhance our understanding of endodermal specification, we conducted a cis-regulatory analysis of the hox11/13b gene across a range of developmental stages up to 60 hours post-fertilization. We identify Ets, Eve, and Tcf as direct regulators of hox11/13b, and we show that their combinatorial control drives the endoderm-specific and dynamic early expression of hox11/13b. Furthermore, we show that its late expression in the hindgut is controlled by an inter-modular AND logic gate, in which two separate regulatory modules are both required but neither alone is sufficient

Throughput improvement for multi-hop UAV relaying

Unmanned aerial vehicle (UAV) relaying is one of the main technologies for UAV communications. It uses UAVs as relays in the sky to provide reliable wireless connection between remote users. In this paper, we consider a multi-hop UAV relaying system. To improve the spectrum efficiency of the system, we maximize the average end-to-end throughput from the source to the destination by jointly optimizing the bandwidth allocated to each hop, the transmit power for the source and relays, and the trajectories of the UAVs, subject to constraints on the total spectrum bandwidth, the average and peak transmit power, the UAV mobility and collision avoidance, and the information-causality of multi-hop relaying. The formulated optimization is non-convex. We propose an efficient algorithm to approximate and solve it, using the alternating optimization and successive convex optimization methods. Numerical results show that the proposed optimization significantly outperforms other benchmark schemes, verifying the effectiveness of our scheme