The problem of relaxed real-time scheduling stabilization of nonlinear systems in the Takagi-Sugeno fuzzy model form is studied by proposing a new alterable-weights-based ranking switching mechanism. ...Thanks to the proposed alterable-weights-based ranking switching mechanism, a new fuzzy switching controller is developed with a set of activated modes that are adjusted by the real-time joint distribution of normalized fuzzy weighting functions. It is worth noting that those existing real-time scheduling stabilization results can be improved without introducing additional offline computational burden while solving control gain matrices. More importantly, less conservative stabilization conditions lead to a smaller degree of the fuzzy homogenous polynomially parameter-dependent switching controller, and thus, less online computational burden is required in the actual application. The effectiveness and superiority of the proposed method are verified by two simulation examples in the numerical section.
This article designs a fully distributed resilient control method for networked multigroup systems in the face of unknown unbounded false data injection (FDI) attacks. The considered multigroup ...systems contain cooperative agents and adversarial attackers. FDI attacks on the multigroup systems include unknown unbounded injections on the local feedback state and communication channels among the network topology. A fully distributed resilient control method is proposed to guarantee the uniformly ultimately bounded containment convergence. In particular, the proposed method consists of the original cyber-physical layer and a virtual resilient layer. The method is further refined to deal with the case when both cyber-physical and virtual layers are subjected to unknown unbounded attacks. The efficacy of the proposed results is first validated on two simulation examples for both linear and nonlinear multigroup systems, and then evaluated on a modified IEEE 34-bus feeder system, emulated in a controller/hardware-in-the-loop experimental platform, to regulate frequency and voltage for islanded microgrid against malicious attacks.
Summary
This paper is concerned with the probabilistic‐constrained filtering problem for a class of time‐varying systems with stochastic nonlinearities and state constraints. An improved static ...event‐triggering scheme is used to reduce unnecessary signal transmissions on the communication channel, where a time‐varying triggering parameter is designed according to engineering practice. The aim of the problem addressed is to design a time‐varying filter such that (1) the prescribed probabilistic constraints on the estimation error are satisfied (ie, the probability for the estimation error to be confined to the given ellipsoidal set is larger than a prescribed value) and (2) the ellipsoid is minimized at each time instant in the sense of the matrix norm. First, the probabilistic constraints are handled by means of the multidimensional Chebyshev bounds. By using recursive matrix inequalities, stochastic analysis is conducted to establish sufficient conditions for the existence of the desired probabilistic‐constrained filter. Then, a recursive optimization algorithm is proposed to design the filter gain matrices. Finally, a simulation example is proposed to demonstrate the effectiveness and applicability of the proposed method.
In this article, we investigate the consensus problem for high-order nonlinear multiagent systems (MASs) with an uncertain leader under event-triggered communication. Compared with the existing ...consensus results for nonlinear MASs under event-triggered communication, the class of systems considered is more general, while achieving better performance in term of asymptotic tracking. To estimate the unknown parameters of the uncertain leader, distributed intermediate parameter estimators based on event-triggered communication mechanism are first introduced. To guarantee that high-order derivatives exist when applying the backstepping method, such estimators are further modified to obtain final estimators having a polynomial form by using the Hermite interpolation method. Moreover, novel high-order filters are proposed to generate local reference signals and to ensure the existence of high-order derivatives of the filter states. Based on the developed filters, a backstepping-based decentralized adaptive controller is developed. It is proved that consensus errors are asymptotically convergent with the developed method. Finally, simulation examples are provided to show the effectiveness of the proposed method.
Instead of using organic solvents, a deep eutectic solvent (DES) composed of tetrabutylammonium bromide and imidazole (Bu4NBr/Im) was employed as a solvent for the first time to synthesize covalent ...organic frameworks (COFs). Due to the low vapor pressure of the Bu4NBr/Im‐based DES, a new carboxyl‐functionalized COF (TpPa‐COOH) was synthesized under environmental pressure. The as‐synthesized TpPa‐COOH has open channels, and the DES can be removed completely from the pores. The dye adsorption performance of TpPa‐COOH was examined for three organic dyes with similar molecular sizes: one anionic dye (eosin B, EB) and two cationic dyes (methylene blue, MB and safranine T, ST). TpPa‐COOH showed an excellent selective adsorption effect on MB and ST. The electronegative keto form in TpPa‐COOH might help to form electrostatic and π–π interactions between the π‐stacking frameworks of TpPa‐COOH and the positive plane MB and ST molecules. The adsorption isotherms of MB and ST on TpPa‐COOH were further investigated in detail, and the equilibrium adsorption was well modeled by using a Langmuir isotherm model. Together with hydrogen bonding, TpPa‐COOH showed higher adsorption capacity for ST than for MB (1135 vs. 410 mg g−1). These results could provide a guidance for the green synthesis of adsorbents in removing organic dyes from wastewater.
Waste not: A deep eutectic solvent has been used as a green solvent for the first time to synthesize a new carboxyl‐functionalized covalent organic framework, TpPa‐COOH, under environmental pressure. The as‐synthesized TpPa‐COOH exhibited good crystallinity, with ordered, open channels. Significantly, its high adsorption capacity could be used to remove cationic organic dyes from wastewater.
To improve the voltage and power sharing of distributed generations, the hierarchical controls are widely used in microgrids while the dependent communication network makes it difficult to ensure the ...performance under limited bandwidth. In this paper, a predictive voltage hierarchical controller is designed. With the delayed secondary PI compensation signals, an inner-loop robust control is designed in the primary controller, ensuring stable voltage tracking. Then, a predictive controller is designed to provide neighbor and local predictions, such that the data integrity is improved by an accurate predictive compensation under bidirectional data-loss. Final case study results verify the effectiveness of the proposed method.
The lithium (Li)–air battery has an ultrahigh theoretical specific energy, however, even in pure oxygen (O2), the vulnerability of conventional organic electrolytes and carbon cathodes towards ...reaction intermediates, especially O2−, and corrosive oxidation and crack/pulverization of Li metal anode lead to poor cycling stability of the Li‐air battery. Even worse, the water and/or CO2 in air bring parasitic reactions and safety issues. Therefore, applying such systems in open‐air environment is challenging. Herein, contrary to previous assertions, we have found that CO2 can improve the stability of both anode and electrolyte, and a high‐performance rechargeable Li–O2/CO2 battery is developed. The CO2 not only facilitates the in situ formation of a passivated protective Li2CO3 film on the Li anode, but also restrains side reactions involving electrolyte and cathode by capturing O2−. Moreover, the Pd/CNT catalyst in the cathode can extend the battery lifespan by effectively tuning the product morphology and catalyzing the decomposition of Li2CO3. The Li–O2/CO2 battery achieves a full discharge capacity of 6628 mAh g−1 and a long life of 715 cycles, which is even better than those of pure Li–O2 batteries.
CO2 can do: CO2 makes Li–O2 batteries more stable. On the anode side, CO2 can facilitate the formation of a protective and self‐healing Li2CO3 film, which can expel the H2O and aggressive intermediates during cycling. The cathode and electrolyte are also protected because the O2− intermediate is captured by CO2 to prevent the formation of 1O2.
Circular RNAs (circRNAs) have received increasing attention in human tumor research. However, there are still a large number of unknown circRNAs that need to be deciphered. The aim of this study is ...to unearth novel circRNAs as well as their action mechanisms in hepatocellular carcinoma (HCC).
A combinative strategy of big data mining, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and computational biology was employed to dig HCC-related circRNAs and to explore their potential action mechanisms. A connectivity map (CMap) analysis was conducted to identify potential therapeutic agents for HCC.
Six differently expressed circRNAs were obtained from three Gene Expression Omnibus microarray datasets (GSE78520, GSE94508 and GSE97332) using the RobustRankAggreg method. Following the RT-qPCR corroboration, three circRNAs (hsa_circRNA_102166, hsa_circRNA_100291 and hsa_circRNA_104515) were selected for further analysis. miRNA response elements of the three circRNAs were predicted. Five circRNA-miRNA interactions including two circRNAs (hsa_circRNA_104515 and hsa_circRNA_100291) and five miRNAs (hsa-miR-1303, hsa-miR-142-5p, hsa-miR-877-5p, hsa-miR-583 and hsa-miR-1276) were identified. Then, 1424 target genes of the above five miRNAs and 3278 differently expressed genes (DEGs) on HCC were collected. By intersecting the miRNA target genes and the DEGs, we acquired 172 overlapped genes. A protein-protein interaction network based on the 172 genes was established, with seven hubgenes (JUN, MYCN, AR, ESR1, FOXO1, IGF1 and CD34) determined from the network. The Gene Oncology, Kyoto Encyclopedia of Genes and Genomes and Reactome enrichment analyses revealed that the seven hubgenes were linked with some cancer-related biological functions and pathways. Additionally, three bioactive chemicals (decitabine, BW-B70C and gefitinib) based on the seven hubgenes were identified as therapeutic options for HCC by the CMap analysis.
Our study provides a novel insight into the pathogenesis and therapy of HCC from the circRNA-miRNA-mRNA network view.
In commercial buildings, about 40%-50% of the total electricity consumption is attributed to Heating, Ventilation, and Air Conditioning (HVAC) systems, which places an economic burden on building ...operators. In this paper, we intend to minimize the energy cost of an HVAC system in a multi-zone commercial building with the consideration of random zone occupancy, thermal comfort, and indoor air quality comfort. Due to the existence of unknown thermal dynamics models, parameter uncertainties (e.g., outdoor temperature, electricity price, and number of occupants), spatially and temporally coupled constraints associated with indoor temperature and CO 2 concentration, a large discrete solution space, and a non-convex and non-separable objective function, it is very challenging to achieve the above aim. To this end, the above energy cost minimization problem is reformulated as a Markov game. Then, an HVAC control algorithm is proposed to solve the Markov game based on multi-agent deep reinforcement learning with attention mechanism. The proposed algorithm does not require any prior knowledge of uncertain parameters and can operate without knowing building thermal dynamics models. Simulation results based on real-world traces show the effectiveness, robustness and scalability of the proposed algorithm.
This paper deals with the problem of control synthesis of discrete-time Takagi-Sugeno fuzzy systems by employing a novel multiinstant homogenous polynomial approach. A new multiinstant fuzzy control ...scheme and a new class of fuzzy Lyapunov functions, which are homogenous polynomially parameter-dependent on both the current-time normalized fuzzy weighting functions and the past-time normalized fuzzy weighting functions, are proposed for implementing the object of relaxed control synthesis. Then, relaxed stabilization conditions are derived with less conservatism than existing ones. Furthermore, the relaxation quality of obtained stabilization conditions is further ameliorated by developing an efficient slack variable approach, which presents a multipolynomial dependence on the normalized fuzzy weighting functions at the current and past instants of time. Two simulation examples are given to demonstrate the effectiveness and benefits of the results developed in this paper.
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