Most existing trackers based on discriminative correlation filters (DCF) try to introduce predefined regularization term to improve the learning of target objects, e.g., by suppressing background learning or by restricting change rate of correlation filters. However, predefined parameters introduce much effort in tuning them and they still fail to adapt to new situations that the designer did not think of. In this work, a novel approach is proposed to online automatically and adaptively learn spatio-temporal regularization term. Spatially local response map variation is introduced as spatial regularization to make DCF focus on the learning of trust-worthy parts of the object, and global response map variation determines the updating rate of the filter. Extensive experiments on four UAV benchmarks have proven the superiority of our method compared to the state-of-the-art CPU-and GPU-based trackers, with a speed of ∼60 frames per second running on a single CPU.Our tracker is additionally proposed to be applied in UAV localization. Considerable tests in the indoor practical scenarios have proven the effectiveness and versatility of our localization method. The code is available at https: //github.com/vision4robotics/AutoTrack.

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Robust attitude control problem for a three degreeof-freedom (3-DOF) lab helicopter is investigated. The helicopter dynamics involves nonlinearity, uncertainties, and strong interaxis coupling. A robust controller is proposed with three parts: a nominal feedforward controller, a nominal linear quadratic regulation (LQR) controller, and a robust compensator. The LQR controller is applied to deal with a nominal linear error system derived by the feedforward control strategy and linearized approximation, while the robust compensator is designed to restrain the effects of uncertainties, nonlinear properties, and external disturbances. It is shown that the attitude tracking error of the closed-loop system can be guaranteed to converge to any given small neighborhood of the origin in a finite time. Experimental results on the 3-DOF lab helicopter demonstrate the effectiveness of the proposed control strategy.

Formation-containment analysis and design problems for high-order linear time-invariant swarm systems with directed interaction topologies are dealt with respectively. Firstly, protocols are presented for leaders and followers respectively to drive the states of leaders to realize the predefined time-varying formation and propel the states of followers to converge to the convex hull formed by the states of leaders. Secondly, formation-containment problems of swarm systems are transformed into asymptotic stability problems, and an explicit expression of the formation reference function is derived. Sufficient conditions for swarm systems to achieve formation containment are proposed. Furthermore, necessary and sufficient conditions for swarm systems to achieve containment and time-varying formation are presented respectively as special cases. An approach to determine the gain matrices in the protocols is given. It is shown that containment problems, formation control problems, consensus problems and consensus tracking problems can all be treated as special cases of formation-containment problems. Finally, numerical simulations are provided to demonstrate theoretical results. 3440 X. DONG ET AL. swarm systems with switching interaction topologies in [19] and [20]. Consensus tracking problems for high-order LTI swarm systems with both fixed and switching interaction topologies were dealt with by Ni and Cheng in [21]. Li et al. [22] proposed sufficient conditions for high-order LTI swarm systems to achieve consensus tracking, where the control input of the leader is nonzero and not available to any follower.In the multiple leaders case, containment problems that require that the states of followers converge to the convex hull formed by the states of leaders arise. Ji et al.[23] investigated containment problems using a hybrid stop-go control strategy. Meng et al.[24] discussed finite-time containment problems for swarm systems with rigid bodies. Containment problems for first-order swarm systems with undirected switching interaction topologies were studied by Notarstefano et al. in [25]. Cao et al. considered containment problems for first-order and second-order swarm systems with both stationary and dynamic leaders in [26] and [27]. Liu et al. [28] presented necessary and sufficient conditions for first-order and second-order swarm systems to achieve containment. Lou and Hong [29] dealt with containment problems for second-order swarm systems with random switching interaction topologies. However, the dynamics of each agent in [23][24][25][26][27][28][29] is restricted to be of first order or second order. In practical applications, the dynamics of agents may be of high order; thus, containment problems for high-order LTI swarm systems make more sense.Li et al.[30] discussed containment problems for high-order LTI swarm systems with directed interaction topologies. Dong et al. [31] investigated containment problems for high-order LTI singular swarm systems with time delays. Sufficient conditions for high-order LTI ...

Skp and SurA are both periplasmic chaperones involved in the biogenesis of Escherichia coli β-barrel outer membrane proteins (OMPs). It is commonly assumed that SurA plays a major role whereas Skp is a minor factor. However, there is no molecular evidence for whether their roles are redundant. Here, by using different dilution methods, we obtained monodisperse and aggregated forms of OmpC and studied their interactions with Skp and SurA by single-molecule fluorescence resonance energy transfer and fluorescence correlation spectroscopy. We found that Skp can dissolve aggregated OmpC while SurA cannot convert aggregated OmpC into the monodisperse form and the conformations of OmpC recognized by the two chaperones as well as their stoichiometries of binding are different. Our study demonstrates the functional distinctions between Skp and SurA. In particular, the role of Skp is not redundant and is probably more significant under stress conditions.

Time-varying formation control problems for high-order linear time-invariant swarm systems with switching interaction topologies are investigated. A general formation control protocol is proposed firstly. Then using a consensus based approach, necessary and sufficient conditions for swarm systems with switching interaction topologies to achieve a given time-varying formation are presented. An explicit expression of the time-varying formation reference function is given. It is revealed that the switching interaction topologies have no effect on the formation reference function and the motion modes of the formation reference can be specified. Furthermore, necessary and sufficient conditions for formation feasibility are presented. An approach to expand the feasible formation set is given and an algorithm to design the protocol for swarm systems with switching interaction topologies to achieve time-varying formations is provided. Finally, numerical simulations are presented to demonstrate theoretical results.

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