An Anti-Eavesdropping Strategy for Precoding-Aided Spatial Modulation With Rough CSI of Eve

In this paper, an anti-eavesdropping strategy is proposed for secure precoding-aided spatial modulation networks, under the assumption that the rough channel state information of eavesdropper can be obtained at the transmitter. Traditionally, artificial noise (AN) can be always projected into the null-space of the legitimate channel, however it may lead to some security loss since this strategy dispenses with a holistic consideration for secure transmissions. To reduce the computational complexity of our optimization problem, we derive a closed-form expression that is a loose bound of the approximate rate over the illegitimate channel. Then a concave maximization problem is formulated for optimizing the covariance matrix of AN. Simulation results show that our proposed low-complexity scheme performs closely to the method which directly maximizes the approximate secrecy rate expression, and harvests significant secrecy rate gains compared with the traditional null-space projection benchmark

LucidDraw: Efficiently visualizing complex biochemical networks within MATLAB

<p>Abstract</p> <p>Background</p> <p>Biochemical networks play an essential role in systems biology. Rapidly growing network data and versatile research activities call for convenient visualization tools to aid intuitively perceiving abstract structures of networks and gaining insights into the functional implications of networks. There are various kinds of network visualization software, but they are usually not adequate for visual analysis of complex biological networks mainly because of the two reasons: 1) most existing drawing methods suitable for biochemical networks have high computation loads and can hardly achieve near real-time visualization; 2) available network visualization tools are designed for working in certain network modeling platforms, so they are not convenient for general analyses due to lack of broader range of readily accessible numerical utilities.</p> <p>Results</p> <p>We present LucidDraw as a visual analysis tool, which features (a) speed: typical biological networks with several hundreds of nodes can be drawn in a few seconds through a new layout algorithm; (b) ease of use: working within MATLAB makes it convenient to manipulate and analyze the network data using a broad spectrum of sophisticated numerical functions; (c) flexibility: layout styles and incorporation of other available information about functional modules can be controlled by users with little effort, and the output drawings are interactively modifiable.</p> <p>Conclusions</p> <p>Equipped with a new grid layout algorithm proposed here, LucidDraw serves as an auxiliary network analysis tool capable of visualizing complex biological networks in near real-time with controllable layout styles and drawing details. The framework of the algorithm enables easy incorporation of extra biological information, if available, to influence the output layouts with predefined node grouping features.</p

Power Allocation Strategies for Secure Spatial Modulation

In this paper, power allocation (PA) strategies in secure spatial modulation networks, are investigated under the total power constraint. Considering that there is no closed-form expression for secrecy rate (SR), an approximate closed-form expression of SR is derived as an efficient metric to optimize PA factor, which can greatly reduce the computation complexity. Based on this expression, a convex optimization (CO) method of maximizing SR (Max-SR) is proposed accordingly. Furthermore, a method of maximizing the product of signal-to-leakage and noise ratio (SLNR) and artificial noise-to-leakage and noise ratio (Max-P-SAN) is proposed to provide an analytic solution for PA factor with extremely low complexity. Simulation results demonstrate that the SR performance of the proposed CO method is close to that of the optimal PA strategy with exhaustive search, and is better than that of Max-P-SAN in the high signal-to-noise ratio (SNR) region. However, in the low and medium SNR regions, the proposed Max-P-SAN slightly outperforms the proposed CO scheme in terms of SR performance

Automatic Gait Pattern Selection for Legged Robots

An important issue when synthesizing legged locomotion plans is the combinatorial complexity that arises from gait pattern selection. Though it can be defined manually, the gait pattern plays an important role in the feasibility and optimality of a motion with respect to a task. Replacing human intuition with an automatic and efficient approach for gait pattern selection would allow for more autonomous robots, responsive to task and environment changes. To this end, we propose the idea of building a map from task to gait pattern selection for given environment and performance objective. Indeed, we show that for a 2D half-cheetah model and a quadruped robot, a direct mapping between a given task and an optimal gait pattern can be established. We use supervised learning to capture the structure of this map in a form of gait regions. Furthermore, we propose to construct a warm-starting trajectory for each gait region. We empirically show that these warm-starting trajectories improve the convergence speed of our trajectory optimization problem up to 60 times when compared with random initial guesses. Finally, we conduct experimental trials on the ANYmal robot to validate our method.</p

A novel approach for applying active surface pre-stress on surrounding rocks of roadways by backfilling behind surface support

In response to the poor active support effect of the surface protection components in soft coal roadway and the continuous expansion of the broken range of local exposed surrounding rock, which leads to the failure of anchor rod and cables, a mesh grouting surface type prestressed application technology has been developed. The authors conducted post mesh grouting tests on different specifications and models of metal mesh, and obtained the mechanical response characteristics of the support system during the application of active surface prestressing. Based on this, the post mesh grouting tests on the roof and two sides of the mesh under on-site conditions were carried out, verifying the applicability of post mesh grouting technology. The research results indicate that: ① There is a gap between the metal mesh and the coal wall, which leads to poor active support ability. The continuous expansion of the broken range of the exposed surrounding rock is the main controlling factor for the failure of anchor rod and anchor cable support. Filling the uneven structure around the contact surface between the metal mesh and the coal wall, increasing the active support ability of the protective surface components, and comprehensively sealing the surrounding rock are the technical means to improve the anchor mesh support system; ② Injecting and filling between the metal mesh and the surrounding rock can achieve the application of surface active pre-stress. The trend of surface stress change is mainly divided into: the initial stage of constant surface stress, the stage of increasing surface stress, and the stage of reducing surface stress to stable state; ③ During the process of grouting behind the mesh, the trend of changes in surface stress values is closely related to the grouting pressure and deformation of the metal mesh. During the process of increasing surface stress, the grouting pressure and deformation of the metal mesh also increase accordingly; ④ Grouting behind the mesh can effectively alleviate the stress concentration of the cable tray. During the process of increasing the surface stress value, the pre-tightening force of the cable with stress concentration can show a small decrease trend, while the pre-tightening force of the cable with relatively uniform stress shows a synchronous upward trend during the process of increasing the surface stress value. The technologies developed are expected to become supporting technologies for rock bolt support, providing technical and theoretical references for the treatment of complex and difficult roadway