990 research outputs found

    Dynamic Behavior of Interacting between Epidemics and Cascades on Heterogeneous Networks

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    Epidemic spreading and cascading failure are two important dynamical processes over complex networks. They have been investigated separately for a long history. But in the real world, these two dynamics sometimes may interact with each other. In this paper, we explore a model combined with SIR epidemic spreading model and local loads sharing cascading failure model. There exists a critical value of tolerance parameter that whether the epidemic with high infection probability can spread out and infect a fraction of the network in this model. When the tolerance parameter is smaller than the critical value, cascading failure cuts off abundant of paths and blocks the spreading of epidemic locally. While the tolerance parameter is larger than the critical value, epidemic spreads out and infects a fraction of the network. A method for estimating the critical value is proposed. In simulation, we verify the effectiveness of this method in Barab\'asi-Albert (BA) networks

    A Scale-Free Topology Construction Model for Wireless Sensor Networks

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    A local-area and energy-efficient (LAEE) evolution model for wireless sensor networks is proposed. The process of topology evolution is divided into two phases. In the first phase, nodes are distributed randomly in a fixed region. In the second phase, according to the spatial structure of wireless sensor networks, topology evolution starts from the sink, grows with an energy-efficient preferential attachment rule in the new node's local-area, and stops until all nodes are connected into network. Both analysis and simulation results show that the degree distribution of LAEE follows the power law. This topology construction model has better tolerance against energy depletion or random failure than other non-scale-free WSN topologies.Comment: 13pages, 3 figure

    Multiform Adaptive Robot Skill Learning from Humans

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    Object manipulation is a basic element in everyday human lives. Robotic manipulation has progressed from maneuvering single-rigid-body objects with firm grasping to maneuvering soft objects and handling contact-rich actions. Meanwhile, technologies such as robot learning from demonstration have enabled humans to intuitively train robots. This paper discusses a new level of robotic learning-based manipulation. In contrast to the single form of learning from demonstration, we propose a multiform learning approach that integrates additional forms of skill acquisition, including adaptive learning from definition and evaluation. Moreover, going beyond state-of-the-art technologies of handling purely rigid or soft objects in a pseudo-static manner, our work allows robots to learn to handle partly rigid partly soft objects with time-critical skills and sophisticated contact control. Such capability of robotic manipulation offers a variety of new possibilities in human-robot interaction.Comment: Accepted to 2017 Dynamic Systems and Control Conference (DSCC), Tysons Corner, VA, October 11-1

    Robot Composite Learning and the Nunchaku Flipping Challenge

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    Advanced motor skills are essential for robots to physically coexist with humans. Much research on robot dynamics and control has achieved success on hyper robot motor capabilities, but mostly through heavily case-specific engineering. Meanwhile, in terms of robot acquiring skills in a ubiquitous manner, robot learning from human demonstration (LfD) has achieved great progress, but still has limitations handling dynamic skills and compound actions. In this paper, we present a composite learning scheme which goes beyond LfD and integrates robot learning from human definition, demonstration, and evaluation. The method tackles advanced motor skills that require dynamic time-critical maneuver, complex contact control, and handling partly soft partly rigid objects. We also introduce the "nunchaku flipping challenge", an extreme test that puts hard requirements to all these three aspects. Continued from our previous presentations, this paper introduces the latest update of the composite learning scheme and the physical success of the nunchaku flipping challenge

    Threshold for the Outbreak of Cascading Failures in Degree-degree Uncorrelated Networks

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    In complex networks, the failure of one or very few nodes may cause cascading failures. When this dynamical process stops in steady state, the size of the giant component formed by remaining un-failed nodes can be used to measure the severity of cascading failures, which is critically important for estimating the robustness of networks. In this paper, we provide a cascade of overload failure model with local load sharing mechanism, and then explore the threshold of node capacity when the large-scale cascading failures happen and un-failed nodes in steady state cannot connect to each other to form a large connected sub-network. We get the theoretical derivation of this threshold in degree-degree uncorrelated networks, and validate the effectiveness of this method in simulation. This threshold provide us a guidance to improve the network robustness under the premise of limited capacity resource when creating a network and assigning load. Therefore, this threshold is useful and important to analyze the robustness of networks.Comment: 11 pages, 4 figure

    CEO Sensation Seeking and Financial Reporting Quality

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    This study investigates whether CEOs’ sensation seeking is related to their firms’ financial reporting quality. Consistent with a tendency of sensation seekers to defy ethical rules, we find that firms with sensation-seeking CEOs have lower financial reporting quality and higher likelihood of accounting fraud. More specifically, we find that firms led by sensation-seeking CEOs engage in more accrual-based and real earnings management, have higher information opacity and are more likely to have internal control deficiencies and use less conservative accounting. Firms with sensation-seeking CEOs are also more likely to engage in accounting fraud as indicated by the SEC Accounting and Auditing Enforcement Release (AAER). We further find that good corporate governance does not mitigate the adverse effects of sensation-seeking CEOs on financial reporting quality. Finally, we find a positive association between sensation-seeking CEOs and audit fees. Our results are robust to CEO change, instrument variable method and propensity score matching. In summary, our results suggest that the CEO personality trait of sensation seeking plays an important role in financial reporting quality

    Minimally invasive surgery for uterine fibroids

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    The incidence of uterine fibroids, which comprise one of the most common female pelvic tumors, is almost 70–75% forwomen of reproductive age. With the development of surgical techniques and skills, more individuals prefer minimallyinvasive methods to treat uterine fibroids. There is no doubt that minimally invasive surgery has broad use for uterinefibroids. Since laparoscopic myomectomy was first performed in 1979, more methods have been used for uterine fibroids,such as laparoscopic hysterectomy, laparoscopic radiofrequency volumetric thermal ablation, and uterine artery embolization,and each has many variations. In this review, we compared these methods of minimally invasive surgery for uterinefibroids, analyzed their benefits and drawbacks, and discussed their future development
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