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  1. Abstract

    In real-life teleoperation scenarios, the presence of time-varying network delays, particularly in wireless networks, poses significant challenges in maintaining stability in a bilateral teleoperation system. Various approaches have been proposed in the past to address stability concerns; however, these often come at the expense of system transparency. Nevertheless, increasing transparency is crucial in a teleoperation system to enable precise and safe operations, as well as to provide real-time decision-making capabilities for the operator. This paper presents our comprehensive approaches to maximize teleoperation transparency by minimizing system impedance, enhance the wave variable method to handle time-varying network delays, and alleviate non-smooth effects caused by network jitters in bilateral teleoperation. The proposed methodologies take into account the real-world challenges and considerations to ensure the practical applicability and effectiveness of the teleoperation system. Throughout these implementations, passivity analysis is employed to ensure system stability, guaranteeing a reliable and safe teleoperation experience. The proposed approaches were successfully validated in Team Northeastern’s Avatar telepresence system, which achieved the 3rd place in ANA Avatar XPRIZE challenge.

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  2. Free, publicly-accessible full text available May 1, 2024
  3. This paper studies controlling segregation in social networks via exogenous incentives. We construct an edge formation game on a directed graph. A user (node) chooses the probability with which it forms an inter- or intra- community edge based on a utility function that reflects the tradeoff between homophily (preference to connect with individuals that belong to the same group) and the preference to obtain an exogenous incentive. Decisions made by the users to connect with each other determine the evolution of the social network. We explore an algorithmic recommendation mechanism where the exogenous incentive in the utility function is based on weak ties which incentivizes users to connect across communities and mitigates the segregation. This setting leads to a submodular game with a unique Nash equilibrium. In numerical simulations, we explore how the proposed model can be useful in controlling segregation and echo chambers in social networks under various settings. 
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  4. When a mixture of viscous oil and non-colloidal particles displaces air between two parallel plates, the shear-induced migration of particles leads to the gradual accumulation of particles on the advancing oil–air interface. This particle accumulation results in the fingering of an otherwise stable fluid–fluid interface. While previous works have focused on the resultant instability, one unexplored yet striking feature of the experiments is the self-similarity in the concentration profile of the accumulating particles. In this paper, we rationalise this self-similar behaviour by deriving a depth-averaged particle transport equation based on the suspension balance model, following the theoretical framework of Ramachandran ( J. Fluid Mech. , vol. 734, 2013, pp. 219–252). The solutions to the particle transport equation are shown to be self-similar with slight deviations, and in excellent agreement with experimental observations. Our results demonstrate that the combination of the shear-induced migration, the advancing fluid–fluid interface and Taylor dispersion yield the self-similar and gradual accumulation of particles. 
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  5. Abstract

    Consensus on the cause of recent midlatitude circulation changes toward a wavier manner in the Northern Hemisphere has not been reached, albeit a number of studies collectively suggest that this phenomenon is driven by global warming and associated Arctic amplification. Here, through a fingerprint analysis of various global simulations and a tropical heating-imposed experiment, we suggest that the suppression of tropical convection along the Inter Tropical Convergence Zone induced by sea surface temperature (SST) cooling trends over the tropical Eastern Pacific contributed to the increased summertime midlatitude waviness in the past 40 years through the generation of a Rossby-wave-train propagating within the jet waveguide and the reduced north-south temperature gradient. This perspective indicates less of an influence from the Arctic amplification on the observed mid-latitude wave amplification than what was previously estimated. This study also emphasizes the need to better predict the tropical Pacific SST variability in order to project the summer jet waviness and consequent weather extremes.

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  6. null (Ed.)