38,776 research outputs found

    Aggregation of foraging swarms

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    In this paper we consider a continuous-time anisotropic swarm model with an attraction/repulsion function and study its aggregation properties. It is shown that the swarm members will aggregate and eventually form a cohesive cluster of finite size around the swarm center. We also study the swarm cohesiveness when the motion of each agent is a combination of the inter-individual interactions and the interaction of the agent with external environment. Moreover, we extend our results to more general attraction/repulsion functions. The model in this paper is more general than isotropic swarms and our results provide further insight into the effect of the interaction pattern on individual motion in a swarm system

    Robust D-stability of uncertain MIMO systems: LMI criteria

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    The focal point of this paper is to provide some simple and efficient criteria to judge the D{\cal D}-stability of two families of polynomials, i.e., an interval multilinear polynomial matrix family and a polytopic polynomial family. Taking advantage of the uncertain parameter information, we analyze these two classes of uncertain models and give some LMI conditions for the robust stability of the two families. Two examples illustrate the effectiveness of our results

    Frequency Response of Uncertain Systems: Strong Kharitonov-Like Results

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    In this paper, we study the frequency response of uncertain systems using Kharitonov stability theory on first order complex polynomial set. For an interval transfer function, we show that the minimal real part of the frequency response at any fixed frequency is attained at some prescribed vertex transfer functions. By further geometric and algebraic analysis, we identify an index for strict positive realness of interval transfer functions. Some extensions and applications in positivity verification and robust absolute stability of feedback control systems are also presented.Comment: 18 pages, 8 figure

    On Robust Stability of Multivariable Interval Control Systems

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    This paper studies robustness of MIMO control systems with parametric uncertainties, and establishes a lower dimensional robust stability criterion. For control systems with interval transfer matrices, we identify the minimal testing set whose stability can guarantee the stability of the entire uncertain set. Our results improve the results in the literature, and provide a constructive solution to the robustness of a family of MIMO control systems

    Robust Strictly Positive Real Synthesis for Convex Combination of Sixth-Order Polynomials

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    For the two sixth-order polynomials a(s)a(s) and b(s),b(s), Hurwitz stability of their convex combination is necessary and sufficient for the existence of a polynomial c(s)c(s) such that c(s)/a(s)c(s)/a(s) and c(s)/b(s)c(s)/b(s) are both strictly positive real. Our reasoning method is constructive, and is insightful and helpful in solving the general robust strictly positive real synthesis problem

    Coordination of Multiple Dynamic Agents with Asymmetric Interactions

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    In this paper, we consider multiple mobile agents moving in Euclidean space with point mass dynamics. Using a coordination control scheme, we can make the group generate stable flocking motion. The control laws are a combination of attractive/repulsive and alignment forces, and the control law acting on each agent relies on the position information of all agents in the group and the velocity information of its neighbors. By using the control laws, all agent velocities become asymptotically the same, collisions can be avoided between all agents, and the final tight formation minimizes all agent global potentials. Moreover, we show that the velocity of the center of mass is invariant and is equal to the final common velocity. Furthermore, we study the motion of the group when the velocity damping is taken into account. We prove that the common velocity asymptotically approaches zero, and the final configuration minimizes the global potential of all agents. In this case, we can properly modify the control scheme to generate the same stable flocking. Finally, we provide some numerical simulations to further illustrate our results

    Flocking Control of Groups of Mobile Autonomous Agents via Local Feedback

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    This paper considers a group of mobile autonomous agents moving in Euclidean space with point mass dynamics. We introduce a set of coordination control laws that enable the group to generate the desired stable flocking motion. The control laws are a combination of attractive/repulsive and alignment forces. By using the control laws, all agent velocities asymptotically approach the desired velocity, collisions can be avoided between agents, and the final tight formation minimizes all agent potentials. Moreover, we prove that the velocity of the center of mass is always equal to the desired velocity or exponentially converges to the desired value. Furthermore, we study the motion of the group when the velocity damping is taken into account. In this case, we can properly modify the control laws to generate the same stable flocking motion. Finally, for the case that not all agents know the desired final velocity, we show that the desired flocking motion can still be obtained. Numerical simulations are worked out to illustrate our theoretical results

    AdS gravity, SO(2,d) gauge theory and Holography

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    Inspired by the general relation between the boundary global symmetry and the bulk gauge symmetry in AdS/CFT, we reformulate the d+1 dimensional AdS gravity theory as a SO(2,d) gauge theory. In this formalism, the pull back of the bulk equation of motion onto a co-dimension one hypersurface \Sigma can be naturally explained as the SO(2,d) conservation law under a local energy scale of the dual CFT. Providing these conservation laws as well as a SO(2,d) covariant area law are valid for any local energy scale, the bulk Einstein equation will be automatically implied.Comment: 22 pages, no figure

    Evolutionary dynamics of cooperation on interdependent networks with Prisoner's Dilemma and Snowdrift Game

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    The world in which we are living is a huge network of networks and should be described by interdependent networks. The interdependence between networks significantly affects the evolutionary dynamics of cooperation on them. Meanwhile, due to the diversity and complexity of social and biological systems, players on different networks may not interact with each other by the same way, which should be described by multiple models in evolutionary game theory, such as the Prisoner's Dilemma and Snowdrift Game. We therefore study the evolutionary dynamics of cooperation on two interdependent networks playing different games respectively. We clearly evidence that, with the increment of network interdependence, the evolution of cooperation is dramatically promoted on the network playing Prisoner's Dilemma. The cooperation level of the network playing Snowdrift Game reduces correspondingly, although it is almost invisible. In particular, there exists an optimal intermediate region of network interdependence maximizing the growth rate of the evolution of cooperation on the network playing Prisoner's Dilemma. Remarkably, players contacting with other network have advantage in the evolution of cooperation than the others on the same network.Comment: 6 pages, 6 figure

    Free-Space Data-Carrying Bendable Light Communications

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    Bendable light beams have recently seen tremendous applications in optical manipulation, optical imaging, optical routing, micromachining, plasma generation and nonlinear optics. By exploiting curved light beams instead of traditional Gaussian beam for line-of-sight light communications, here we propose and demonstrate the viability of free-space data-carrying bendable light communications along arbitrary trajectories with multiple functionalities. By employing 39.06-Gbit/s 32-ary quadrature amplitude modulation (32-QAM) discrete multi-tone (DMT) signal, we demonstrate free-space bendable light intensity modulated direct detection (IM-DD) communication system under 3 different curved light paths. Moreover, we characterize multiple functionalities of free-space bendable light communications, including bypass obstructions transmission, self-healing transmission, self-broken trajectory transmission, and movable multi-receiver transmission. The observed results indicate that bendable light beams can make free-space optical communications more flexible, more robust and more multifunctional. The demonstrations may open a door to explore more special light beams enabling advanced free-space light communications with enhanced flexibility, robustness and functionality
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