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This paper considers a distributed constrained optimization problem over a multi-agent network in the non-Euclidean sense. The gossip protocol is adopted to relieve the communication burden, which also adapts to the constantly changing topology of the network. Based on this idea, a gossip-based distributed stochastic mirror descent (GB-DSMD) algorithm is proposed to handle the problem under consideration. The performances of GB-DSMD algorithms with constant and diminishing step sizes are analyzed, respectively. When the step size is constant, the error bound between the optimal function value and the expected function value corresponding to the average iteration output of the algorithm is derived. While for the case of the diminishing step size, it is proved that the output of the algorithm uniformly approaches to the optimal value with probability 1. Finally, as a numerical example, the distributed logistic regression is reported to demonstrate the effectiveness of the GB-DSMD algorithm. • A Gossip-Based Distributed Stochastic Mirror Descent (GB-DSMD) algorithm is proposed. • In the proposed algorithm, appropriate step-size can be chosen by each agent based on local information. • The impact of two different step sizes on the performance of GB-DSMD algorithm is analyzed. [ABSTRACT FROM AUTHOR]

This paper is engaged in investigating the observer-based event-triggered output feedback control issue for fractional-order cyber–physical systems with stochastic network attacks, where the order scale of the fractional derivative used is 0 < α < 1. An event-triggered scheme (ETS) with output-independent threshold is proposed to renew the observer input so as to reduce the redundant data communications. Considering the effects of the ETS and network attacks, a novel closed-loop fractional-order control system model is constructed. By making use of fractional-order Lyapunov indirect approach, sufficient conditions that can insure the global stochastic asymptotic stability of the established closed-loop control system are obtained. Moreover, according to the singular value decomposition (SVD) of matrix, the co-design of the gains of the desired observer and controller is addressed by finding the solution of the linear matrix inequalities (LMIs). Finally, a numerical example and a diesel engine control system are provided to validate the feasibility of the adopted observer-based control method. • A simplified ETS is proposed for fractional-order CPSs. • A fractional-order state observer model is constructed by taking the ETS and network attacks into consideration. • The observer-based event-triggered output feedback control problem is firstly considered for fractional-order CPSs with network attacks. • A new sufficient condition for the stability analysis of fractional-order CPSs is obtained, and the gains of the observer and controller are also co-designed. [ABSTRACT FROM AUTHOR]

This paper focuses on admissibility analysis and stabilization for neutral descriptor hybrid systems (NDHSs) with time-varying delays. The main object is to design mode dependent state feedback controller (SFC) and realize admissibility and stabilization of the NDHSs. Sufficient conditions are provided in terms of linear matrix inequalities (LMIs) via constructing integrated L-K functional. Two simulation examples including a partial element equivalent circuit (PEEC) model are used to testify the validity and practicality of the proposed method. [ABSTRACT FROM AUTHOR]

CoFe-layered double oxide derived from Hydrotalcite-like combining biochar (CoFe-LDO-BC) was prepared and applied to catalytic ozonation process for removing methylene blue (MB). The catalyst has not only greater specific surface area (about 26 times and 2 times more than that of BC and LDO respectively) and more abundant oxygen vacancies, but inhibited metal agglomeration and accelerated the electron transfer between Co (III)/Co (II) effectively. TOC analysis revealed mineralization rate of methylene blue was 3.7 × 10−2 min−1 (R2 = 0.996, pH = 9, catalyst dosage = 10 mg, ozone = 0.35 mg/min) in the catalytic ozonation system, much higher than that of single ozone (1.5 ×10−2 min−1, R2 = 0.907). Accordingly, the TOC degradation efficiency increased from 31.6% to 68.25%. Moreover, the lower metal ion leaching made the catalyst still maintain higher mineralization ability, and its mineralization efficiency decreased at only 7.9% point after five cycles. The results from XPS, EPR, NH 3 -TPD and Py-IR confirmed the oxygen vacancies and metal acid sites on catalyst surface could synergistically activate ozone to produce·OH, O 2 ·- and 1O 2 , and·OH was dominating in mineralization process. The degradation pathway of MB in CoFe-LDO-BC+O 3 catalytic system was proposed. This work is helpful for exploring and preparing stable and efficient ozone catalysts. [Display omitted] • Prepared CoFe-LDO-BC has excellent catalytic performance. • Oxygen vacancies and acidic sites synergistically promote the generation of free radicals. • The role of reactive oxygen species in CoFe-LDO-BC+O 3 system was studied. • The degradation pathway of methylene blue by CoFe-LDO-BC+O 3 was given. [ABSTRACT FROM AUTHOR]

Abstract This paper is concerned with the output-feedback stabilization problem for a class of singular linear parameter-varying (LPV) systems. The objective is to design a dynamic output-feedback controller such that the resulting closed-loop system is robustly admissible. Different from the classical gain-scheduling techniques, it is assumed in this paper that the scheduling parameters involved in the plant model are not exactly available for the controller. First, a sufficient and necessary condition for the solvability of the underlying stabilization problem is obtained in the form of general parameter-dependent matrix inequalities. Second, an equivalent transformation is developed to convert the general parameter-dependent conditions into parameter-dependent linear matrix inequalities (LMIs). Third, the singular LPV system whose coefficient matrices take a polytopic form is considered, and the finite LMI-based conditions are derived. Finally, an illustrative example is provided to show the effectiveness of the proposed design methods. [ABSTRACT FROM AUTHOR]

Being a promising potential source for natural gas, methane hydrate (MH) is attracting increasing interest due to its great amount and diverse geographic distribution. The formation of MH is significantly influenced by the properties of sediment media such as porosity and permeability. In this study, in order to have a better understanding on the relationship between MH formation behavior and sediment properties, as well as to synthesize representative hydrate samples, MH was formed in six different sets of mixed-size porous media composed of clay, silt and fine sand, with saline water and circulating methane gas to reflect MH formation with free methane flux in marine sediment. The sediment composition, experimental pressure (15 MPa) and temperature (286.2 K) were chosen based on the SH2 drilling site in the Shenhu area in South China Sea. A two-stage growing behavior was observed for all systems. The gas consumption and hydrate formation rate exhibited positive relations with the permeability and porosity of the sediments. Furthermore, hydrates were found to be preferably formed in the bottom layer of the sediment, which could be attributed to the drastic drop of permeability at the early stage of hydrate formation. Lastly, the hydrate formation rate constant was calculated based on the intrinsic kinetic model and found to be a good reflection of the mass transfer properties of different porous media. [ABSTRACT FROM AUTHOR]

Abstract This paper deals with the fuzzy filtering problem for a class of nonlinear time-delay systems described by T-S fuzzy models. Different from the existing schemes in the literature, this paper aims to solve the fuzzy filtering problem by considering the H ∞ , L 2 − L ∞ and dissipative performance constraints in a unified way. To achieve this purpose, the recently proposed notion of extended dissipativity is applied, which provides an inequality covering the well-known H ∞ , L 2 − L ∞ and dissipative performances. Another purpose of this paper is to design filters involving communication delays. Such filters have a more general form than the delay-free filters that have been largely considered in the traditional studies. In order to design the fuzzy filters under consideration, a novel fuzzy Lyapunov-Krasovskii functional is employed, and delay-dependent conditions for stability and performance analysis of the filtering error system are obtained. Then, LMI-based conditions for the existence of the desired filters are presented. The filter parameters can be obtained by solving the presented LMIs. Finally, the effectiveness of the proposed method is substantiated with an illustrative example. Highlights • The extended dissipative fuzzy filtering problems for nonlinear time-delay systems is solved. • The designed filter includes both delayed states and inputs. • Delay-dependent conditions are derived based on a novel Lyapunov-Krasovskii functional. [ABSTRACT FROM AUTHOR]

• Two bandit algorithms are designed based on the non-Euclidean framework. The Bregman divergence is used as the distance measure in the projection step. • In our algorithms, the potential time delay existing in the feedback process and the limited network resources are taken into account. • The static regret bounds are provided for the ET-DOCO algorithms with delayed bandit feedback. The obtained results show that the two algorithms can ensure a sublinear regret bound if the triggering threshold tends to zero. This paper is concerned with an online distributed convex-constrained optimization problem over a multi-agent network, where the limited network bandwidth and potential feedback delay caused by network communication are considered. To cope with the limited network bandwidth, an event-triggered communication scheme is introduced in information exchange. Then, based on the delayed (i.e., single-point and two-point) bandit feedback, two event-triggered distributed online convex optimization algorithms are developed by utilizing the Bregman divergence in the projection step. Meanwhile, the convergence of the two developed algorithms is analyzed according to the provided static regret bounds achieved by the algorithm. The obtained results show that a sublinear static regret with respect to the time horizon T can be ensured if the triggering threshold gradually approaches zero. In this case, the corresponding order of the regret bounds is also determined by choosing suitable triggering thresholds. Finally, a distributed online regularized linear regression problem is provided as an example to illustrate the effectiveness of the proposed two algorithms. [ABSTRACT FROM AUTHOR]

This note studies the problem of decay-rate-dependent exponential stability for neutral stochastic delay systems with Markovian jumping parameters. First, by introducing an operator D ( x t , i ) as well as a novel Lyapunov–Krasovskii functional, sufficient conditions for exponential stability of system with a decay rate are obtained. Second, the results are extended to the robust exponential estimates for uncertain neutral stochastic delay systems with Markovian jumping parameters. Finally, numerical examples are provided to show the effectiveness of the proposed results. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carrier type imposed selection pressure on microbial recruitment. • Elastic cubic sponges induced closer cooperation within anammox community. • Carrier type affected nitrogen conversion related enzymes and genes abundances. • Elastic cubic sponges improved biofilm activity, EPS and heme c content. The impacts of carrier type on anammox community assembly, species interactions and nitrogen conversion were studied in this work. It was found that in addition to shared species with higher abundance, different carrier types recruited rare species by imposing selection pressure. Results from co-occurrence networks revealed that carrier type strongly influenced interactions between keystone species inhabiting within anammox biofilm through potentially inducing niche differences. Overall, elastic cubic sponges would lead to closer cooperation between different populations, whereas plastic hollow cylinders would trigger fiercer competition. Meanwhile, the results based on metagenomics sequencing showed carrier type significantly affected nitrogen conversion related genes abundances, and higher reads number was detected on the elastic cubic sponges. The information obtained in this work could provide some valuable information for the selection and optimization of carrier type in the anammox process. [ABSTRACT FROM AUTHOR]

A biochar composite loaded with nZVI particles and MoS 2 nanosheets (nZVI/MoS 2 -BC) was prepared by calcination and hydrothermal methods, and could activate peroxymonosulfate (PMS) more efficiently to produce reactive oxygen species (ROSs) for refractory organics degradation. Due to the interaction between nZVI and MoS 2 , the reaction sites increased with nZVI dispersing more evenly and multitudinous MoS 2 growing on the surface of biochar. PMS activated by nZVI/MoS 2 -BC produced SO 4 ·-, ·OH, O 2 ·- and 1O 2 to degrade pollutants. In addition, the increase of specific surface area and electrical conductivity accelerated the electron transfer from pollutions to metastable PMS to achieve pollutant degradation. The effects of catalyst dosage, PMS dosage, pH, inorganic anions and humic acid, and Cl- concentration in catalytic oxidation system were investigated. nZVI/MoS 2 -BC was regenerated by calcination at 300 ℃ after four cycles, and could still keep higher rhodamine B (Rh-B) removal (90.88%). Various pollutants removal efficiency could reach greater than 80% in nZVI/MoS 2 -BC catalytic oxidation system, such as Rh-B, methylene blue, chloramphenicol, tetracycline and bisphenol A. The combination of H 2 O 2 and PMS could greatly reduce the cost, improve the pollutant removal and shorten the reaction time by changing the interval time and content ratio of oxidants addition. nZVI/MoS 2 -BC applied to the H 2 O 2 /PMS double oxidation system exhibited excellent removal capability of pollutants. The intermediates of Rh-B were analyzed and the degradation pathways were proposed in nZVI/MoS 2 -BC and H 2 O 2 /PMS double oxidation system. [Display omitted] • Biochar loaded with nZVI and MoS 2 manifested excellent catalytic performance. • The mechanism of ROSs generated pathways was presented in the catalytic system. • Universality of the nZVI/MoS 2 -BC was found in degradation of refractory organics. • H 2 O 2 + PMS could significantly improve the economy and effect of catalytic system. [ABSTRACT FROM AUTHOR]

This paper considers the problem of solving distributed online optimization over a network that consists of multiple interacting nodes. Each node in the network is endowed with a sequence of loss functions, each of which is revealed to the node after a decision has been committed. The goal of the network is to minimize the cumulative loss functions of nodes in a distributed fashion, while subject to two types of information constraints, namely, message quantization and bandit feedback. To this end, a quantized distributed online bandit optimization algorithm is proposed by adopting random quantization operation and one-point gradient estimator. We show the convergence of the algorithm by establishing an O (d T 3 / 4) regret bound, where d is the dimension of states and T is the total number of rounds. Finally, an online distributed quadratic programming problem is investigated to validate the theoretical findings of the paper. [ABSTRACT FROM AUTHOR]

This paper investigates the tracking control problem for nonlinear networked systems with repeated scalar nonlinearities. A polynomial fuzzy model based approach is employed to model the nonlinear systems. A polynomial fuzzy controller is designed to drive the system states to follow those of a given reference model. Imperfect communication links with two typical phenomenons (i.e., data packet dropout and signal quantization) are taken into account. Sufficient conditions are obtained in terms of sum of squares, which guarantee the stochastic stability and H ∞ performance constraint. Finally, a simulation example is given to illustrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This article focuses on the resilient fixed-time stabilization of switched neural networks (SNNs) under impulsive deception attacks. A novel theorem for the fixed-time stability of impulsive systems is established by virtue of the comparison principle. Existing fixed-time stability theorems for impulsive systems assume that the impulsive strength is not greater than 1, while the proposed theorem removes this assumption. SNNs subjected to impulsive deception attacks are modeled as impulsive systems. Some sufficient criteria are derived to ensure the stabilization of SNNs in fixed time. The estimation of the upper bound for the settling time is also given. The influence of impulsive attacks on the convergence time is discussed. A numerical example and an application to Chua's circuit system are given to demonstrate the effectiveness of the theoretical results. [ABSTRACT FROM AUTHOR]

[Display omitted] • N-G promoted anammox average nitrogen removal efficiency by 17.57%. • N-G increased anammox biomass from 18.10% to 28.30%. • N-G improved anammox microbial function in terms of "Metabolism". • N-G enriched the genes involved in nitrogen removal to varing degree. • N-G upregulated the genes controlling extracellular polymeric substance secretion. The effect of 50 mg/L nitrogen-doped graphene (N-G) on anammox microbial guild was studied by metagenomics in this paper. The continuous experiment results showed the average NRE improved by 17.57% with N-G addition. The metagenomic analysis revealed N-G significantly increased the relative abundance of dominant AnAOB (Candidatus Kuenenia) from 18.10% to 28.30%. And the FISH assay further manifested N-G promoted the growth of AnAOB biomass. Meanwhile, metagenomics indicated that N-G enriched the abundance of genes (Hzs , Hdh , NosZ , NorB , NirK , NirS and NrfA) involved in nitrogen metabolism to varying degrees. Furthermore, N-G not only improved the microbial functionality in terms of "Metabolism", but markedly upregulated the abundance of c-di-GMP synthesized genes and genes related to quinolone signal molecule, which contributed to more EPS content and better sludge settleability. In brief, this study provided a novel perspective for anammox biomass enrichment, which may be valuable for practical engineering applications of anammox. [ABSTRACT FROM AUTHOR]

Abstract: This paper is concerned with the problem of exponential filter design for linear systems simultaneously with distributed delays, Markovian jumping parameters and norm-bounded parametric uncertainties. The purpose is to design full-order mode-dependent filters such that the filtering error system is not only mean-square robustly exponentially stable with a specified decay rate but also satisfies an performance requirement. First, sufficient conditions for the stability and performance analysis of the filtering error system are derived based on a novel version of mode-dependent Lyapunov–Krasovskii functional. Then, delay-dependent and decay-rate-dependent conditions for the existence of desired filters are obtained in terms of linear matrix inequalities (LMIs). The filter coefficients can be computed by using feasible solutions of the presented LMIs. Finally, a numerical example is provided to demonstrate the effectiveness of the proposed design method. [Copyright &y& Elsevier]

Abstract: This paper is concerned with the problem of designing filters for a class of nonlinear networked control systems (NCSs) with transmission delays and packet losses. This problem is investigated under the following assumptions: (i) the delay is constant and known, (ii) the packet-loss process is described by a Bernoulli distributed white sequence, and (iii) the probability of the packet-loss process is unknown but bounded. The first two assumptions are well known in the literature of NCSs, while the last one may often arise in practical networks due to modeling or measurement errors. Under the aforementioned assumptions, delay-dependent conditions for the solvability of the addressed problem are presented in terms of linear matrix inequalities. Numerical examples are also included to illustrate the effectiveness of the proposed method. [Copyright &y& Elsevier]

Abstract: Gas hydrate-bearing porous media are natural or artificial porous deposits (soil sediments or coal) that contain gas hydrate in their pores. The mechanical properties of gas hydrate-bearing porous media are very necessary for researches on gas production and hydrate-based technology. This paper summarized the advances of the research on the mechanical properties of the gas hydrate deposit, from the experimental and numerical aspects. Also, this paper points out that research on the mechanical properties of synthesized gas hydrate porous media (coalbed seam) is necessary for coal and gas outburst prevention and mitigation. First, the theories about strength and deformation are introduced; second, a simple constitutive model for gas hydrate-bearing sediments is referred; third, the experimental and numerical researches are discussed; finally, this paper provides some suggestions for future study on mechanical properties of gas hydrate – bearing porous media. [Copyright &y& Elsevier]

Abstract: This paper is concerned with the problem of absolute exponential stability analysis for a class of continuous-time systems with sector-bounded nonlinearities and interval time-varying delays. Absolute exponential stability criteria, which depend not only on the delay range but also on the decay rate, are derived by using a novel Lyapunov functional. These criteria are expressed in the form of linear matrix inequalities (LMIs) and they can easily be checked. By solving these LMIs, estimates of the exponential decay rate and decay coefficient are obtained. A numerical example is provided to demonstrate the effectiveness of the proposed method. [Copyright &y& Elsevier]

Abstract: This paper is concerned with the problem of delay-dependent stability analysis for discrete-time systems with interval-like time-varying delays and the problem of stabilization for discrete-time linear systems via time-delayed controllers. The first problem is solved by applying a novel Lyapunov functional, and an improved delay-dependent stability criterion is obtained in terms of a linear matrix inequality. Based on this, a sufficient condition for the solvability of the second problem is presented. The reduced conservatism of the proposed stability result is shown through a numerical example, while the applicability of the time-delayed controller design method is demonstrated by an inverted pendulum system. [Copyright &y& Elsevier]

Abstract: This paper investigates the robust control problem for uncertain continuous-time piecewise systems by using the piecewise continuous Lyapunov function. The uncertainties of the systems under consideration are expressed in a linear fractional form. A strict linear matrix inequality approach is developed to obtain stability condition and performance. The controller design problem is solved by exploiting the cone complementarity linearization (CCL) method, which can be cast into an iterative minimization problem subject to LMI constraints. Finally two examples are given to illustrate the application of the proposed approach. [Copyright &y& Elsevier]

Abstract: This Letter investigates the problem of stability analysis for a class of high-order neural networks with time-varying delays. The delays are bounded but not necessarily differentiable. Based on the Lyapunov stability theory together with the linear matrix inequality (LMI) approach and the use of Halanay inequality, sufficient conditions guaranteeing the global exponential stability of the equilibrium point of the considered neural networks are presented. Two numerical examples are provided to demonstrate the effectiveness of the proposed stability criteria. [Copyright &y& Elsevier]

Magnetite/reduced graphene oxide nanocomposites (Fe 3 O 4 -rGO NCs) and magnetite nanoparticles (Fe 3 O 4 NPs) were added to enhance biohydrogen (bioH 2) production in dark fermentation. Concentration of supplements from 10 to 100 mg/L was appropriate to enhance bioH 2 production, and inhibition appeared once concentration exceeded 100 mg/L. The best bioH 2 yield was 198.30 mL/g glucose at 100 mg/L Fe 3 O 4 NPs and 225.60 mL/g glucose at 100 mg/L Fe 3 O 4 -rGO NCs, which was 42.97% and 62.65% higher than that in the blank group, respectively. Both Fe 3 O 4 NPs and Fe 3 O 4 -rGO NCs could intensify butyrate-type fermentation and change the hydrogen-producing microorganism cells morphology, but the enhancement effect of Fe 3 O 4 -rGO NCs was superior. Microbial community structure analysis showed that Clostridium-sensu-stricto-1 became more dominant ultimately by Fe 3 O 4 -rGO NCs. [Display omitted] • Fe 3 O 4 -rGO NCs were synthesized to enhance biohydrogen yield. • Fe 3 O 4 -rGO NCs enhanced disproportionation reaction of propionate to butyrate. • Fe 3 O 4 NPs and Fe 3 O 4 -rGO NCs could make the microbial cells longer and thicker. • Fe 3 O 4 -rGO NCs involved in intracellular and extracellular electron transfer. • Fe 3 O 4 -rGO NCs increased the abundance of Clostridium-sensu-stricto-1. [ABSTRACT FROM AUTHOR]

This paper considers the synchronization problem of nonlinear complex dynamical networks (CDNs) through intermittent pinning control approach on time scales. Both the internal delay and coupling delay are considered in the nonlinear CDNs. To deal with the nonlinearity in the delayed complex network, a new scale-limited differential inequality is proposed. Based on the Lyapunov approach and the theory of time scales, some novel exponential synchronization criteria are derived, which are applicable not only to the continuous/discrete CDNs but also to the case of continuous–discrete hybrid time domains. Two numerical examples are provided to certify the validness of the proposed design method. [ABSTRACT FROM AUTHOR]