Cascading failures in coupled networks with both inner-dependency and inter-dependency links

We study the percolation in coupled networks with both inner-dependency and inter-dependency links, where the inner- and inter-dependency links represent the dependencies between nodes in the same or different networks, respectively. We find that when most of dependency links are inner- or inter-ones, the coupled networks system is fragile and makes a discontinuous percolation transition. However, when the numbers of two types of dependency links are close to each other, the system is robust and makes a continuous percolation transition. This indicates that the high density of dependency links could not always lead to a discontinuous percolation transition as the previous studies. More interestingly, although the robustness of the system can be optimized by adjusting the ratio of the two types of dependency links, there exists a critical average degree of the networks for coupled random networks, below which the crossover of the two types of percolation transitions disappears, and the system will always demonstrate a discontinuous percolation transition. We also develop an approach to analyze this model, which is agreement with the simulation results well.Comment: 9 pages, 4 figure

Outdated Measurements Are Still Useful For Multi-Sensor Linear Control Systems With Random Communication Delays

Linear systems are a widely used model for the control tasks of modern cyber physical systems around their stationary state(s), e.g., smart grids, remote health applications, and autonomous driving systems. Specifically, each sensor first compresses its own measurement and then sends it to the controller. Due to the inevitable random communication delay, the controller needs to decide how to fuse the received information to compute the desired control action. Suppose a fusion center has received several measurements over time. One common belief is that the control decision should be made solely based on the latest measurement of each sensor while ignoring the older/stale measurements from the same sensor. This work shows that while such a strategy is optimal in a single-sensor environment, it can be strictly suboptimal for a multi-sensor system. Namely, if one properly fuses both the latest and outdated measurements from each of the sensors, one can strictly improve the underlying control system performance. The numerical evaluation shows that even at a very low communication rate of 8 bits per measurement per sensor, the proposed scheme achieves a state variance of only 5% away from the best possible achievable L2 norm. It is 15% better than the MMSE fusion scheme using exclusively the freshest measurements (while discarding outdated ones)

1-(4-Fluoro­phen­yl)-3-hydr­oxy-3-phenyl­prop-2-en-1-one

In the crystal structure the title compound, C15H11FO2, the molecule exists in the enol form. It is stabilized by an intra­molecular O—H⋯O hydrogen bond, in which the donor O—H and acceptor H⋯O distances are almost equal. The dihedral angle between the two benzene rings is 22.30 (4)°

Robust Optimization Design of Bolt-Shotcrete Support Structure in Tunnel

The uncertainty of rock and soil parameters is one of the key problems to limit the stability of tunnel support structure. Based on this, a robust optimization design method is proposed to reduce the sensitivity of support system to the uncertainty of rock and soil parameters. By defining the design parameters, noise factors and system response, a robust design system for bolt-shotcrete support structure is established. The non-dominant solutions of system robustness and support cost consist of the Pareto Front, then an knee point recognition method is designed to further filter all non-dominant solutions and determine the only optimal solution. The robust optimization design of the bolt-shotcrete support structure is carried out with a tunnel as the engineering background. The results show that the method can not only improve the stability and adaptability of the supporting structure, but also reduce the economic cost to the greatest extent, which provides a reference for the optimization design of other geotechnical engineering supporting structures

Risk Assessment Based on Combined Weighting-Cloud Model of Tunnel Construction

In order to reduce the tunnel construction accidents and ensure the safety of personnel, a comprehensive assessment method of tunnel construction risk based on combination weighting and cloud model is constructed according to the characteristics of tunnel construction. The risk assessment index system is established based on researches on engineering geological condition, natural environmental condition, Tunnel engineering design scheme and construction management. On this basis, the tunnel risk is divided into 4 levels and the index risk level standard is proposed. In order to improve the rationality of weighting, a weight calculation method based on AHP, entropy method and Lagrange multiplier method is constructed. Finally, the normal cloud generator is used to form comparison pictures of risk clouds and standard clouds, which demonstrates the risk status of the evaluation indexes at all levels. With reference to Deda Tunnel of Sichuan-Tibet Railway engineering of high integrated risk level, management decision-making is required. The evaluation results are basically consistent with engineering practices, proving that the method has good feasibility and applicability

Impact of Clay Stabilizer on the Methane Desorption Kinetics and Isotherms of Longmaxi Shale, China

Knowing methane desorption characteristics is essential to define the contribution of adsorbed gas to gas well production. To evaluate the synthetic effect of a clay stabilizer solution on methane desorption kinetics and isotherms pertaining to Longmaxi shale, an experimental setup was designed based on the volumetric method. The objective was to conduct experiments on methane adsorption and desorption kinetics and isotherms before and after clay stabilizer treatments. The experimental data were a good fit for both the intraparticle diffusion model and the Freundlich isotherm model. We analyzed the effect of the clay stabilizer on desorption kinetics and isotherms. Results show that clay stabilizer can obviously improve the diffusion rate constant and reduce the methane adsorption amount. Moreover, we analyzed the desorption efficiency before and after treatment as well as the adsorbed methane content. The results show that a higher desorption efficiency after treatment can be observed when the pressure is higher than 6.84 MPa. Meanwhile, the adsorbed methane content before and after treatment all increase when the pressure decreases, and clay stabilizer can obviously promote the adsorbed methane to free gas when the pressure is lower than 19 MPa. This can also be applied to the optimization formulation of slickwater and the design of gas well production

Effects of heritability on evolutionary cooperation in spatial prisoner’s dilemma games

AbstractWe study the effects of heritability on the evolution of the spatial prisoner’s dilemma game. In our model, the fitness of each player is composed of the instantaneous payoff from the interactions and the inherited fitness from the last generation. Based on extensive simulations, we find that the density of cooperators is enhanced by increasing the heritability of players over a wide range of the model parameter. The mean fitness of cooperators and defectors are also studied for understanding our results