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Relative measurements are exploited to cooperatively detect and recover faults in the positioning of Mobile Agent (MA) Swarms (MASs). First, a network vertex fault detection method based on edge testing is proposed. For each edge, a property that has a functional relationship with the properties of its two vertices is measured and tested. Based on the edge testing results of the network, the maximum likelihood principle is used to identify the vertex fault sources. Second, an edge distance testing method based on the noncentral chi-square distribution is developed for detecting faults in the Global Navigation Satellite System (GNSS) positioning of MASs. Third, a recovery strategy for faults in the positioning of MASs based on distance measurement is provided. The effectiveness of the proposed methods is validated by a simulation case in which an MAS passes through a GNSS spoofing zone. The proposed methods are conducive to increasing the robustness of the positioning of MASs in complex environments. The main novelties include the following: (A) network vertex fault detection is based on concrete probability analysis rather than simple majority voting, and (B) the relation of detectability and recoverability of MAS positioning faults with the structure of the relative measurement network is first disclosed.

Na3V1.5Cr0.5(PO4)3 cycled at 30 °C shows fast capacity decay, due to the migration of V ions into the electrolyte and the loss of V3+/V4+ redox.

The ability to monitor lithium deposition on the anodes in real time is becoming progressively more important due to the development of advanced anode technology. Given the fact that the detrimental Li deposits are always on the micron scale, electron paramagnetic resonance (EPR) happens to be a very effective and selective detection technology due to the skin effect. Here, quantitative in situ 1D EPR imaging is carried out with a magnetic field gradient to achieve a one-dimensional spatial resolution along the Li growth direction in a capillary cell. The quantification of Li deposits is carefully calibrated using a 1,1-diphenyl-2-picrylhydrazyl standard, and a processing method is presented to correct the double integration of the Dysonian line from the metallic Li. The Li deposition processes are compared in two different electrolytes. For the electrolyte containing fluoroethylene carbonate (FEC) additive, the fitting results of Dysonian lines suggest that the plated Li has a larger dimension of the microstructure and the stripping proceeds more uniformly. It thus accounts for the higher Coulombic efficiency in the electrolyte with FEC. In situ EPR imaging also suggests that the Sand’s capacity varies with the electrolytes. The forced growth of dendritic Li is carried out at a very large current density using a derivative operando EPR method to monitor the growth locus of the Li dendrites, indicating a tip-growing mechanism. This work can be instructive for those who are engaged in the study of electro-deposited lithium using in situ EPR imaging technology.

Na

Anion redox contributes to the anomalous capacity exceeding the theoretical limit of layered oxides. However, double-high activity and reversibility is challenging due to the structural rearrangement and potential oxygen loss. Here, we propose a strategy for constructing a dual honeycomb-superlattice structure in Na

This work mainly addresses the attitude tracking problem for rigid spacecraft subject to external disturbances, actuator saturation and faults. Firstly, a finite-time prescribed performance function (FTPPF) is defined to limit the tracking errors of original system into the boundary constraints and converge into a small residual set around zero within the preassigned time. An error transformation is employed to transform the constrained control system into an unconstraint one to simplify the relevant controller design. With the aid of the hyperbolic tangent function, the actuator saturation is approximated, and the approximation error is included into the external disturbances to be restrained. Then, a linear extended state observer (LESO) is developed to address the synthetic disturbances mentioned above with fewer tuning parameters. Wherein, the nominal matrix replaces the actual input gains is employed in the LESO design to avoid the singularity in disturbance rejection resulted from saturation approximation. Furthermore, an observer-based fault-tolerant tracking controller is derived to stabilize the attitude tracking error system and realize the disturbance compensation. Compared with the existing methods based on neutral networks (NNs) or fuzzy approximations, the developed scheme can achieve simultaneous estimations of multiple disturbances with simpler design. Meanwhile, the disadvantage that the NNs and fuzzy approximations are only effective on some compact sets is avoided. Finally, numerical simulations and analyses are employed to verify the superiority and robustness of the proposed method.

An event-driven neural network–based fault-tolerant tracking control scheme is investigated for uncertain mechanical systems with performance guaranteed in the presence of unknown actuator faults and external disturbances. Compared with the existing works, the primary advantage is that the detections and identifications of actuator faults are not required, whereas the convergence rate and tracking accuracy can be guaranteed a priori by constructing an adaptive tracking controller with a few aperiodic updates. Moreover, by using the norm-bounding skill, only two adaptive parameters are needed to update online, which dramatically decreases the complexity of the corresponding adaptive schemes. Finally, applications to the attitude stabilization and tracking control of the flexible spacecraft are used to validate the effectiveness of the proposed control scheme.

Inadequate immune response remains a critical cause of immunotherapy failure in various tumor treatments. Herein, we offer a new approach to achieve a cross-talk between innate and adaptive immune responses based on a new nanoplatform for photothermal therapeutics. The nanoplatform was formed by linking titanium carbide MXene with Mn

Lithium-excess manganese layered oxide Li2 MnO3 , attracts much attention as a cathode in Li-ion batteries, due to the low cost and the ultrahigh theoretical capacity (≈460 mA h g-1 ). However, it delivers a low reversible practical capacity ( 4.5 V). Herein, heavy fluorination (9.5%) is successfully implemented in the layered anionic framework of a Li-Mn-O-F (LMOF) cathode through a unique ion-exchange route. F substitution with O stabilizes the layered anionic framework, completely inhibits the O2 evolution during the first cycle, and greatly enhances the reversibility of oxygen redox, delivering an ultrahigh reversible capacity of 389 mA h g-1 , which is 85% of the theoretical capacity of Li2 MnO3 . Moreover, it also induces a thin spinel shell coherently forming on the particle surface, which greatly improves the surface structure stability, making LMOF exhibit a superior cycling stability (a capacity retention of 91.8% after 120 cycles at 50 mA g-1 ) and excellent rate capability. These findings stress the importance of stabilizing the anionic framework in developing high-performance low-cost cathodes for next-generation Li-ion batteries.

This paper investigates a novel finite-time saturated deployment control approach for the tethered satellite system in the presence of uncertain dynamics and space perturbations, as well as state constraints. First, an integral Lyapunov function is constructed to remove the hard state constraints characterized by a finite-time convergent performance function. Then, a backstepping finite-time deployment controller is devised via using an extended state observer (ESO) to approach the unknown dynamics, perturbations and saturation deviation. Compared with the existing finite-time control methods, the prominent advantage of the proposed one is that the finite-time saturated deployment control is achieved without violating the state constraints and using fractional state feedback. Finally, an illustrative example is organized to validate the effectiveness of the proposed approach.

With consideration of motion control performance and efficient information communication, the synchronization problem on communication connectivity preservation and guaranteed consensus performance for networked mechanical systems has attracted considerable attention in recent years. Different from the existing works, this article investigates a brand-new appointed-time consensus control approach for uncertain networked Euler-Lagrange systems on a directed graph via exploring the prescribed performance control structure. First, a two-layer prescribed performance envelope is formulated via using an appointed-time convergent function for position-related and velocity-related consensus errors, respectively. Then, a simple state-feedback virtual controller with online adaptive performance adjustment is developed to preserve the communication connectivity. Moreover, to guarantee the velocity consensus of the networked systems and improve the position consensus accuracy, an appointed-time adaptive controller is designed by applying the norm inequality to the system uncertainties and external disturbances. Compared to the existing consensus control approaches, the prime advantage of the proposed one is that the constraints generated from the communication ranges are approximated by a time-varying contractive performance envelope, wherein, the appointed-time convergence and steady-state tracking accuracy are preassigned a priori. Meanwhile, no repeated logarithmic error transformations are required in the relevant controller design, which implies that the complexity of the devised control laws has decreased dramatically. Finally, two groups of illustrative examples are organized to validate the effectiveness of the proposed consensus control approach.

Here, a m-xylene bisphosphonate immobilized tentacle-type cellulose monolith (BP-PCM) is prepared by atom transfer radical polymerization for lysozyme purification. In the preparation, the m-xylene bisphosphonate was anchored glycidyl methacrylate and then polymerized to enhance the flexibility of the ligands to improve lysozyme adsorption capacity, and glycerol monomethacrylate serves as spacer to further optimize the layers structure and ligands density of the grafted tentacles for satisfactory adsorption capacity. The maximum static and dynamic adsorption capacity (10% breakthrough) of BP-PCM reach to 169.6 and 102.6 mg mL−1, respectively. Moreover, BP-PCM displays weak nonspecific adsorption and is able to successfully enrich lysozyme from diluted chicken egg white, indicating the excellent selectivity. The results demonstrated that BP-PCM is promising for use as high-capacity protein chromatography.

The trajectory tracking control of the quadrotor unmanned aerial vehicle (QUAV) is investigated. The aim of this paper is to develop a novel trajectory tracking control method considering model uncertainties and external disturbances with finite-time stability and prescribed performance of the attitude. Firstly, the trajectory tracking control system of the QUAV is decoupled into two subsystems, i.e., position and attitude subsystems, wherein, backstepping technique is used to design the position tracking controller. Then, to guarantee the tracking performance of the attitude subsystem, a finite-time convergent performance function is developed, and a prescribed performance attitude controller is devised via using integral barrier Lyapunov function thereafter. In the design process of the above two controllers, ESO is used to estimate and compensate multiple uncertainties and disturbances simultaneously. Moreover, the fractional state feedback and discontinuous phenomenon of the control law are directly avoided to achieve the finite-time convergence rate. Finally, an illustrative example is organized to verify the effectiveness of the proposed approach.

Energy management system is very critical for solving the energy problem of a long endurance stratospheric airship. But the researches about the energy management system and energy management strategy for a stratospheric airship are rare. This paper presents the hybrid energy system consisting of one renewable energy system and two energy storage systems. Combined with the models of energy harvesting, balance and storage, and the thermal model of the PV (Photovoltaic) panel, the details of the rule-based energy management strategy to cooperate the three energy sources or storage devices: photovoltaic, lithium battery and fuel cell are obtained. Furthermore, the energy management strategy in the situation of a storage system failure is proposed to ensure the operation of the airborne equipment. In the course of the investigation, the power curves and the state of charge of the energy storage systems are reported in detail to prove the validity and applicability of the management strategies. It indicates that the energy system of the airship can provide uninterrupted energy to control system and payload system, but can not resist the wind drag after LB failure, which will increase the difficulty of the trajectory planning. The results indicate that the strategy is helpful for planning energy management.

The high altitude solar-powered airships have been proposed for use as long endurance platforms, for a variety of military and civilian applications. The challenges of perpetual endurance flight require the airship to generate sufficient power over a wide range of operational latitudes so that the aerial vehicle can keep station through high wind events and maintain persistence. This paper provides a theoretical approach to analyzing the perpetual endurance performance of a high altitude solar-powered airship. According to the features of stratospheric airship and the theoretical model, a custom tool is developed using MATLAB computer program when the airship operates in the cruise condition. The effects of the operational latitudes, wind velocities and solar array areas on the energy ratio are numerically investigated in detail, and the required areas of solar array under the conditions of different minimum energy ratio were discussed. The results showed that the solar-powered airships faced severe operational limitations at high latitudes in the winter, especially in the high wind. In addition, a case study was analyzed to demonstrate the effectiveness of this approach to predicting the perpetual endurance region. The results demonstrated that the theoretical approach suggested a pathway towards planning the flight date and location for an airship.

The three-dimensional multiple constrained guidance problem for a hypersonic gliding vehicle (HGV) against a stationary ground target in dive phase is investigated. A coupled nonlinear dynamic model is established on account of the bank-to-turn control scheme adopted by the HGV, which formulates the relation between line-of-sight angles and trajectory control variables. On this basis, a finite-time nonlinear disturbance observer is introduced to estimate the lumped uncertainty. Utilizing the estimation as feedforward compensation, a guidance law based on the adaptive multivariable super-twisting sliding mode control is designed to realize precise strike with designated impact angles. The finite-time stability of closed-loop guidance system is proven through the Lyapunov technique. Numerical simulations are executed to validate the mission adaptiveness and the robustness of the presented guidance scheme.

The maintenance of the nominal multirevolution elliptic halo orbit, whose special features can benefit mercurial explorations, is first investigated through Monte–Carlo simulations in the elliptic Sun–Mercury model, and then validated in the high-fidelity ephemeris model. The receding horizon control strategy solved by the indirect Radau pseudospectral method demonstrates that the orbit can be maintained robustly with respect to very large initial deviations. Moreover, the result proves that the elliptic Sun–Mercury model is an accurate approximation.

Heavy metal pollution of water source continues to be one of the most serious environmental problems which have attracted major global concern. Here, a macroporous chitin microsphere is prepared by surfactant micelle swelling strategy followed by modification with tetraethylenepentamine for Pb2+ removal from wastewater. The resultant adsorbent not only exhibits fast adsorption kinetic (>80% of its equilibrium uptake within 20 min) but also has high adsorption capacity of 218.4 ± 6.59 mg/g and excellent reusability (>75% of its initial adsorption capacity after five adsorption/desorption cycles). More importantly, under the continuous operating mode, the adsorbent can treat about 39,000 kg water/kg adsorbent, and the Pb2+ concentration decreases from 2000 μg/L to smaller than 10 μg/L, meeting the drinking water standard recommended by the World Health Organization (10 μg/L). All results indicate that the tetraethylenepentamine-modified macroporous chitin microspheres have great potential in the treatment of heavy metal contamination.

This paper refers to finding a new solution to the attitude tracking control problem for reusable launch vehicle in reentry phase with multiple disturbances. We address the problem by a new scheme, which integrating a nonlinear active disturbance rejection controller with a meta-heuristic algorithm. Firstly, the attitude model with strict-feedback form is constructed to facilitate the controller design. Then, an attitude tracking controller based on the nonlinear active disturbance rejection control is built. A linear tracking differentiator is utilized to arrange a transient profile and extract derivatives of the attitude reference input. A linear extended state observer with model-assisted term is chosen to estimate the multiple disturbances. A feedback control law with the model-assisted information and observer estimations is deduced to achieve rapid response. Futhermore, a novel meta-heuristic algorithm named grey wolf optimizer is developed to search for the optimal controller parameters by minimizing a criterion function. Finally, the main simulation results are given to validate the superiority of the proposed approach.