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The convergence of sensing, computing, communication and control elements drives the traditional point-to-point control systems towards networked control systems. Sampled-data control systems, which focus on the significant interplay between sampling and control, play a critical role in modern networked control systems, including intelligent transportation systems, smart grids, and advanced manufacturing systems. This paper presents a survey of methods and trends in non-uniform sampled-data control systems, where sampling and control actions are performed in an aperiodic manner. First, some fundamental issues of both continuous- and discrete-time sampled-data control systems are discussed. Next, main methods in both continuous-time and discrete-time domains are elaborated, respectively. Then, event-triggered sampling, under which sampling is executed only when the system needs attention, is examined. Typical triggering mechanisms in the existing literature are reviewed and classified into four types according to different threshold functions. Furthermore, two applications in terms of automated vehicle platoons and islanded microgrids are provided to demonstrate that sampled-data control methods are capable to support relevant practical application scenarios. Finally, several challenging issues are envisioned to direct future research. [ABSTRACT FROM AUTHOR]

Global asymptotic stability is an important issue for wide applications of recurrent neural networks with time-varying delays. The Lyapunov–Krasovskii functional method is a powerful tool to check the global asymptotic stability of a delayed recurrent neural network. When the Lyapunov–Krasovskii functional method is employed, three steps are necessary in order to derive a global asymptotic stability criterion: (i) constructing a Lyapunov–Krasovskii functional, (ii) estimating the derivative of the Lyapunov–Krasovskii functional, and (iii) formulating a global asymptotic stability criterion. This paper provides an overview of recent developments in each step with insightful understanding. In the first step, some existing Lyapunov–Krasovskii functionals for stability of delayed recurrent neural networks are anatomized. In the second step, a free-weighting matrix approach, an integral inequality approach and its recent developments, reciprocally convex inequalities and S -procedure are analyzed in detail. In the third step, linear convex and quadratic convex approaches, together with the refinement of allowable delay sets are reviewed. Finally, some challenging issues are presented to guide the future research. [ABSTRACT FROM AUTHOR]

This paper is concerned with stability of a linear system with a time-varying delay. First, an improved reciprocally convex inequality including some existing ones as its special cases is derived. Compared with an extended reciprocally convex inequality recently reported, the improved reciprocally convex inequality can provide a maximum lower bound with less slack matrix variables for some reciprocally convex combinations. Second, an augmented Lyapunov–Krasovskii functional is tailored for the use of a second-order Bessel–Legendre inequality. Third, a stability criterion is derived by employing the proposed reciprocally convex inequality and the augmented Lyapunov–Krasovskii functional. Finally, two well-studied numerical examples are given to show that the obtained stability criterion can produce a larger upper bound of the time-varying delay than some existing criteria. [ABSTRACT FROM AUTHOR]

Recent research has shown that one can obtain a less conservative stability criterion for a continuous-time linear system with a time-varying delay by introducing a Lyapunov-Krasovskii functional with a polynomial matrix on the time-varying delay. This paper aims at analysing the stability of discrete-time linear systems with time-varying delays by introducing a delay-square-dependent Lyapunov functional. A novel convex method is presented to formulate a less conservative stability criterion, which is demonstrated through numerical simulation. Moreover, it is also shown that, if the polynomial inequality method is employed, the resultant stability criterion is inapplicable due to its extremely high numerical complexity. [ABSTRACT FROM AUTHOR]

This paper is concerned with stability of linear discrete time-delay systems. Note that a tighter estimation on a finite-sum term appearing in the forward difference of some Lyapunov functional leads to a less conservative delay-dependent stability criterion. By using Abel lemma, a novel finite-sum inequality is established, which can provide a tighter estimation than the ones in the literature for the finite-sum term. Applying this Abel lemma-based finite-sum inequality, a stability criterion for linear discrete time-delay systems is derived. It is shown through numerical examples that the stability criterion can provide a larger admissible maximum upper bound than stability criteria using a Jensen-type inequality approach and a free-weighting matrix approach. [ABSTRACT FROM AUTHOR]

This paper is concerned with event-based H ∞ filtering for sampled-data systems. First, an event-based data packet processor is introduced to release sampled measurement outputs only if an event condition is violated. As a result, communication resources can be saved significantly while preserving the desired H ∞ performance. Second, the resulting filtering error system is modeled as a system with an interval time-varying delay. By employing the Lyapunov–Krasovskii functional approach, a new bounded real lemma (BRL) is established such that the filtering error system is asymptotically stable with the prescribed H ∞ performance. Third, by performing an invertible linear transformation on the filtering error system, a linear matrix inequality (LMI)-based sufficient condition, which is equivalent to the condition in the BRL, is obtained on the feasibility of the event-based H ∞ filtering problem. Consequently, suitable H ∞ filters and the event parameters in the event condition can be co-designed provided that a set of LMIs are satisfied. Finally, a mechanical system with two masses and two springs is given to show the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper is concerned with the H ∞ performance of discrete-time networked systems subject to network-induced delays and malicious packet dropouts. First, the introduction of a data packet processor enables us to calculate both network-induced delays and the number of consecutive malicious packet dropouts explicitly. Second, a novel Lyapunov functional is constructed, whose forward difference along with the trajectory of the closed-loop system is estimated as a quartic polynomial. A class of necessary and sufficient conditions on such an inequality are established by using the Finsler lemma. By employing the Lyapunov method, a bounded real condition is formulated, which depends on the upper bound of network-induced delays and the maximum number of consecutive malicious packet dropouts. Therefore, their effects on H ∞ performance can be investigated simultaneously. Finally, the effectiveness of the proposed method is shown through an inverted pendulum system. [ABSTRACT FROM AUTHOR]

Abstract: This paper is concerned with global asymptotic stability for a class of generalized neural networks with interval time-varying delays by constructing a new Lyapunov–Krasovskii functional which includes some integral terms in the form of . Some useful integral inequalities are established for the derivatives of those integral terms introduced in the Lyapunov–Krasovskii functional. A matrix-based quadratic convex approach is introduced to prove not only the negative definiteness of the derivative of the Lyapunov–Krasovskii functional, but also the positive definiteness of the Lyapunov–Krasovskii functional. Some novel stability criteria are formulated in two cases, respectively, where the time-varying delay is continuous uniformly bounded and where the time-varying delay is differentiable uniformly bounded with its time-derivative bounded by constant lower and upper bounds. These criteria are applicable to both static neural networks and local field neural networks. The effectiveness of the proposed method is demonstrated by two numerical examples. [Copyright &y& Elsevier]

Abstract: This paper is concerned with the network-based filtering for a stochastic system, where data transmission from the stochastic system to a filter is completed via a communication network. Network-induced delays, packet dropouts and packet disorders are unavoidable due to the use of the network. First, a logic zero-order-hold (ZOH) is designed to discard the disordered packets actively. The network-induced delays and packet dropouts are modeled as an interval time-varying delay. By decomposing the delay interval into subintervals uniformly, the filter to be designed is modeled as a Markov jumping filter with modes governed by a Markov chain. In order to work out the transition rate from one mode to another, a logic jumping-like trigger is embedded into the logic ZOH to simulate the switching of the Markov process. Second, based on the Markov jumping filter model together with a new integral inequality in the stochastic setting, a novel bounded real lemma is presented to ensure that the resultant filtering error system is mean exponentially stable with a prescribed performance. Then, a sufficient condition on the existence of desired Markov jumping filters is provided in terms of a set of linear matrix inequalities. Finally, an air vehicle system is employed to show effectiveness of the proposed design method. [Copyright &y& Elsevier]

Abstract: The mechanism of the Ni-mediated coupling reaction of CO2 with epoxyethane has been extensively investigated by the density functional theory (DFT) calculations. All the possible pathways are examined, and their corresponding energetics are demonstrated. On the basis of the comparison of three mechanisms, it is determined that the preferred mechanism for the catalytic production of cyclic carbonate can be divided into three main steps involving epoxide oxidative addition, carbon dioxide insertion, and reductive elimination of cyclic carbonate (route IC), none of which contains significantly large barriers. The overall reaction is exothermic and the rate-determining step is associated with the reductive elimination of cyclic carbonate from the six-membered metallacyclic intermediate 15. All reaction pathways with solvent effects taken into consideration have been studied by means of a PCM-UAHF model. The calculations indicate that the introduction of solvent effects does not change the general trends for the reaction potential energy surfaces. Our results provide a theoretical support for the reaction mechanism proposed from previous experimental observations. At the same time, the present theoretical study gives a clear profile for the cycloaddition of carbon dioxide with epoxyethane promoted by (Ph3P)2Ni. [Copyright &y& Elsevier]

Abstract: This paper deals with the problem of delay-dependent robust filtering for uncertain linear systems with time-varying delay. Two cases of time-varying delays are fully considered; one is the time-varying delay being continuous uniformly bounded while the other is the time-varying delay being differentiable uniformly bounded with delay-derivative bounded by a constant. A stable linear filter is designed to ensure that the filtering error system is asymptotically stable with a prescribed level of noise attenuation. Based on a new integral inequality, delay-dependent sufficient conditions for the existence of such a filter are established in terms of linear matrix inequalities (LMIs). Through deriving these conditions, neither model transformation nor bounding technique for cross terms is employed. Moreover, the relationship between the sufficient conditions for the two cases of time-varying delay is disclosed. Finally, two examples are also given to illustrate the effectiveness of the proposed methodology. [Copyright &y& Elsevier]

Abstract: The integral-inequality method is a new way of tackling the delay-dependent stabilization problem for a linear system with time-varying state and input delays: . In this paper, a new integral inequality for quadratic terms is first established. Then, it is used to obtain a new state- and input-delay-dependent criterion that ensures the stability of the closed-loop system with a memoryless state feedback controller. Finally, some numerical examples are presented to demonstrate that control systems designed based on the criterion are effective, even though neither nor is stabilizable. [Copyright &y& Elsevier]

Abstract: Hydro(solvo)thermal in situ ligand synthesis has rapidly developed over the past several years due to its effectiveness, simplicity and environmental friendliness. More than 10 types of in situ ligand reactions have been enumerated, which include carbonnd formation, hydroxylation, tetrazole formation, triazole formation, substitution, alkylation, ether bond formation, hydrolysis, oxidation–hydrolysis, acylation, amination and decarboxylation. Hydrothermal in situ ligand synthesis has become a powerful approach in the crystal engineering of coordination complexes and in organic synthesis, and is becoming an alternative approach in the isolation of organic isomers. In the crystal engineering of coordination complexes, in situ ligand synthesis is suitable to prepare novel coordination complexes from metal ions and organic precursors and most of these complexes are not accessible from a direct reaction of metal ions and ligands. In organic synthesis, hydrothermal in situ ligand syntheses have become very useful pathways to organic ligands, which are difficult to obtain by routine synthetic methods. In isolating organic isomers, in situ ligand synthesis is becoming an alternative route because in some special cases, only one of the several isomers of a ligand is found in crystalline complexes involving in situ ligand reactions. [Copyright &y& Elsevier]

Abstract: Three new metal pyridinecarboxylates, namely [Co2(pydc)2(H2O)5] (1), [Mn(pydc)(H2O)2] (2) and [Cd2(OH)2(2,4-pydc)] (3), were hydrothermally synthesized. X-ray single crystal structural analysis revealed: 1 and 2 have polymeric one-dimensional chain-like structure constructed by dinuclear cobalt units and Mn–O chains, respectively; 3 has a three-dimensional layer pillared structure constructed from inorganic Cd–O layer and pydc pillars. 1 shows antiferromagnetic interaction but 2 shows alternative antiferromagnetic and ferromagnetic interactions. [Copyright &y& Elsevier]

Three cluster-based coordination polymers, namely [Zn3(bpy)3(hip)2] · 5H2O (1), [Co3(bpy)3(hip)2] · 5H2O (2) and [Cd3(bpy)3(hip)2] (3) (bpy=2,2′-bipyridine, hip=4-hydroxyl-isophthalate) were synthesized and structurally characterized. X-ray single-crystal structural analyses revealed that both 1 and 2 crystallize in the chiral space group P21, while 3 crystallizes in the centric space group Pccn. Compounds 1 and 2 are isomorphous and both have (4,4) topological layered structures constructed from trinuclear metal clusters. Compound 3 also shows layered structure of (4,4) topology constructed from trinulear Cd(II) cores. The layers are stacked in a staggered ⋯ABAB⋯ fashion in 1 and 2 but in an overlapped ⋯AAA⋯ fashion in 3. There are two types of coordination modes of hip ligand in 1 and 2 but only one in 3. The structural difference between 1 (or 2) and 3 may be attributed to the difference of metal ion nature such as the ionic radius and coordination preference, resulting in the different orientation fashions of the auxiliary bpy ligands, stacking fashions of the layers, as well as chirality of the crystals. The chiral structures of 1 and 2 were also confirmed by measurements of powder second-harmonic-generation (SHG) measurements, which show that 1 and 2 have SHG intensity of 0.50 and 0.02 relative to that of urea, respectively. [Copyright &y& Elsevier]

The reaction of Ag2O and carboxylate ligands in ammonium solution results in three coordination polymers, [Ag(fbc)]n 1, [Ag2(cpd)]n 2 and [Ag2(idc)]n 3, where fbcH is 4-fluorobenzoic acid, cpdH2 is cyclopentane-1,1-dicarboxylic acid and idcH2 is iminodiacetic acid. The X-ray crystal structural analysis indicates that compounds 1 and 2 are two-dimensional frameworks and 3 is a three-dimensional framework. All the three complexes show clear Ag–Ag bonds and high cytotoxicity properties to normal cells and carcinoma cells. [Copyright &y& Elsevier]

Two compounds (NH4)2[M(dod)(H2O)4]2V10O28·6H2O (M = Zn, Mn) have been prepared in aqueous medium. X-ray single-structure analyses reveal that they are isostructural and crystallize in the triclinic space group P1. The structures of the two compounds consist of decavanadate anionic clusters and dimeric [M(dod)(H2O)4]24+ units, in which the two oxygen atoms from dod ligands ligating M2+ are in a cis fashion. There are a variety of hydrogen bonds including O–H⋯O and N–H⋯O among lattice water molecules, ammonium cations, oxygen atoms of decavanadate and oxygen atoms of dod, which extend the structures into three-dimensional supramolecular arrays. [Copyright &y& Elsevier]

This paper is concerned with sufficient conditions for a class of matrix-valued polynomial inequalities on closed intervals and their application to H ∞ filtering for linear systems with time-varying delays. First, a class of higher degree matrix-valued polynomial inequalities are transformed into the first degree matrix-valued polynomial inequalities by introducing some slack matrices. As a result, a convex property is applied to derive sufficient conditions for a class of higher degree matrix-valued polynomial inequalities on closed intervals. Second, by choosing a Lyapunov–Krasovskii functional with a quadratic matrix-valued polynomial on a time-varying delay, and estimating its time-derivative as a third-degree matrix-valued polynomial on the time-varying delay, the proposed sufficient conditions are utilized to formulate a novel bounded real lemma on the existence of H ∞ filters for time-delay systems. Third, some algorithms to filter design are provided and discussed in detail. It is pointed out that, if the filter gain is derived through a generalized inverse matrix method, it may be a fake solution, which is demonstrated through a liquid monopropellant rocket motor with a pressure feeding system. [ABSTRACT FROM AUTHOR]

Abstract: The solvothermal treatment of cobalt nitrate (or zinc acetate), ethylenediamine and dicarboxylate in acetonitrile produced two one-dimensional coordination polymers [Co(mimz)2(ox)] n (1) and [Zn(mimz)2(ip)] n (2) (mimz = 2-methylimidazoline, ox=oxalate, ip=isophthalate) which ligand involving in situ formation of imidazoline ligand by cycloaddition reaction of ethylenediamine and acetonitrile. [Copyright &y& Elsevier]

The salt decay on the surface of stone cultural relics is the greatest damage to its loaded information. Polycarboxylate modifiers can reduce salt crystallization pressure and/or change crystal habits, thereby becoming a new method for controlling salt crystallization damage in pores. However, the lack of precise regulation of crystal morphology by modifier and the unclear relationship between modifier and crystal transformation during salt growth hinder its practical application. Herein, diethylenetriamine pentamethylene phosphonic acid (DTPMP), phosphorus-free, green polyaspartic acid (PASP) and polyepoxysuccinic acid (PESA), as well as three composite modifiers composed of DTPMP and PESA (M-1:9, M-2:8, M-3:7) were systematically investigated. Video microscope, scanning electron microscope, and X-ray diffraction showed that the addition of these modifier could obviously transform the crystal morphology of sodium sulfate(thenardite) from prism into dendrite, which was related to the significant change in the intensity ratios of corresponding peaks on the different crystal planes. Molecular dynamics simulations were conducted to investigate the interactions of PASP and PESA on different surfaces of sodium sulfate, revealing that the crystal transformation of sodium sulfate was mainly influenced by the coordination/adsorption effect of the modifiers on the (010) plane. All modifiers were used for sandstone desalination, and the clean and desalted sandstones were analyzed for desalting efficiency, colorimetry and porosity, which showed that PESA, PASP and composite modifier M-3:7 all promoted the precipitation of sodium sulfate on the surface. Especially, composite modifier M-3:7 prefers to change the crystallization and morphology of sodium sulfate from prism into dendritic flower, which can be used to protect to sandstone cultural relics from salt damage. • The polycarboxylate PASP and PESA, and composite modifier can modify crystal habit of sodium sulfate. • Molecular dynamics is used to elucidate the modification mechanism of PASP and PESA. • The presence of PESA, PASP, M-3:7 is conducive to the in-situ protection of sandstone cultural relics. [ABSTRACT FROM AUTHOR]

This article proposes a distributed model-based cooperative controller to improve voltage synchronization in DC-isolated microgrids that are powered by variable renewable energy sources. Based on the second-order voltage dynamics of dc–dc buck converters, we aim to develop an integral-based linear-quadratic regulator that synchronizes not only the output voltages but also their derivatives. It is necessary not only in reducing voltage ripples and their integrals but also in eliminating steady-state errors. This objective is achieved mainly by introducing a global performance index, which minimizes neighbor synchronization errors, apart from local synchronization errors, and thus transfers the interactions between the dc–dc buck converters from the physical layer to the communication layer. Furthermore, it is demonstrated that the proposed controller ensures global system stability according to the Lyapunov stability theory. Several simulations are made to show the effectiveness of the proposed technique in terms of voltage synchronization and stability, voltage ripple elimination, and voltage convergence speed when input voltage disturbances are present. • Distributed cooperative voltage control for DC-isolated microgrids is proposed. • Interconnected converters represent decomposed agents in the communication layer. • Global performance index minimizes local and neighbor synchronization errors. • Integral-based linear quadratic regulator eliminates dynamic and steady-state errors. • Global stability is proved using Lyapunov approach. [ABSTRACT FROM AUTHOR]

We have successfully synthesized the Hong Kong University of Science and Technology-1 (HKUST-1) metal organic framework (MOF)-graphene oxide (GO) hybrids (noted as H-G) onto carbon nanotube film (CNTF) and further electrochemically deposited poly(3,4-ethylenedioxythiophene) (PEDOT) to give a flexible conductive porous electrode (noted as PEDOT/H-G-CNTF), which shows excellent electrochemical performance due to the mesoporous structure of H-G in PEDOT/H-15G-CNTF hybrid. Electrochemical studies show that the PEDOT/H-15G-CNTF exhibits an exceptional areal capacitance of 128 mF cm −2 at 10 mV s −1 than that of PEDOT/HKUST-1-CNTF (81 mF cm −2 ) in a three-electrode system, indicating that the incorporation of GO into the hybrids effectively boosts the capacitive performance of PEDOT/HKUST-1-CNTF. To further explore the capacitive performance of PEDOT/H-15G-CNTF electrode, a symmetric flexible solid-state supercapacitor has also been assembled and tested. The assembled optimum flexible supercapacitor shows superior areal capacitance (37.8 mF cm −2 ) at the scan rate of 5 mV s −1 , and good charge/discharge capability using PVA/H 3 PO 4 gel electrolyte. The volumetric energy density for this device is calculated to be 0.051 mWh cm −3 , with a volumetric power density is 2.1 mW cm −3 at current density of 0.4 mA cm −2 . The device exhibits the excellent electrochemical property and mechanical properties under different bending angles. [ABSTRACT FROM AUTHOR]

[Display omitted] • The layer formation during dip coating is investigated numerically and experimentally. • New criteria is introduced for determining the demarcations of the layer. • The withdrawal process successively undergoes two regimes. • Models are proposed to predict the heights of the demarcations between different regions. Thus far studies on dip coating focus on the asymptotic layer thickness which is reached only in the lower part of the layer when the withdrawal time is sufficiently long. This work attempts to offer a complete description of the evolution of layer thickness profile with withdrawal time for vertical withdrawal of Newtonian fluids using simulation and the Buckingham π theorem. The results show that over time, the withdrawal process successively undergoes two regimes: (I) an unsteady film region and an unsteady meniscus region and (II) an unsteady film region connected to a steady meniscus region through an unsteady meniscus region. The controlling factors for the two regimes are identified at different values of capillary number and Reynolds number. Models are proposed to predict the heights of the demarcations between different regions. The models agree well with experimental results when the controlling forces are viscous force and gravity. [ABSTRACT FROM AUTHOR]

To guarantee the safety and reliability of drilling riser after emergency disconnection, it is significant to investigate and refrain recoil response of the riser. This paper deals with the problem of Takagi–Sugeno (T-S) fuzzy recoil dynamic modeling and optimal recoil control of nonlinear deepwater drilling riser systems subject to friction resistance of fluid discharge and platform heave motion. First, a nonlinear recoil control model of coupled riser-tensioner is proposed by taking the nonlinear top tension of tensioner into account. Then, a T-S fuzzy dynamic model of the riser-tensioner system is established to approximate the original nonlinear one by using fuzzy modeling scheme. Third, an augmented T-S fuzzy model of riser system is proposed, where the linear exosystem model of friction resistance and platform heave motion is utilized. Fourth, a finite-time fuzzy optimal recoil controller is designed to suppress the recoil response of the riser, the existence and design algorithm of the fuzzy optimal recoil controller are derived. Simulation results demonstrate that the nonlinear recoil model is more accurate than the existing linear one to describe the recoil characteristics of the riser, and the fuzzy optimal recoil controllers are effective to reduce recoil responses and guarantee the safety of the riser significantly. • A nonlinear recoil dynamic model of coupled riser-tensioner is proposed by considering the nonlinear tension. • An augmented T-S fuzzy dynamical model of riser system is developed, where an exosystem of friction resistance is utilized. • Finite-time fuzzy optimal recoil controllers are designed to suppress the recoil response of the riser. • The fuzzy optimal recoil controllers are effective to reduce recoil responses and guarantee the safety of the riser. [ABSTRACT FROM AUTHOR]

This study addresses discrete dynamic modelling and the optimal recoil control problem of deepwater drilling riser systems subject to the friction resistance of fluid discharge and platform heave motion. First, a discrete-time exosystem model for friction resistance of drilling fluid discharge is developed; then, a discrete-time dynamic model of platform heave motion is established. Third, a finite-time discrete optimal recoil controller with feedforward compensation mechanisms was designed. The optimal recoil controller gains can be obtained by iteratively solving discrete equations. The simulation results show that under the discrete feedforward and feedback optimal recoil controller and pure feedback optimal recoil controller, the recoil movements of the riser system are significantly restrained. Moreover, the former is more effective than the latter at resisting the riser recoil response. • A discrete-time exosystem model of the friction resistance induced by drilling fluid discharge on the riser is proposed. • A discrete-time dynamic model of irregular heave motion of drilling platform is established. • A discrete-time recoil control model of the drilling riser system subject to viscous resistance of fluid discharge and platform heave motion is developed. • A finite-timediscrete optimal recoil control scheme with feedforward mechanism is designed to suppress the recoil response of the riser. [ABSTRACT FROM AUTHOR]

Lanthanide metal-organic frameworks (Ln-MOFs) have exhibited remarkable capabilities in color change, luminescence, proton conduction through the strategic modification of metal nodes, organic ligands and channels or pores. By modifying the electron-deficient bipyridinium to contain carboxylic acid moieties and coordinating them with the luninescent Eu3+ ion, a unique and versatile Eu-MOF has been synthesized. Under UV light conditions, the complex shows an obvious color change from colorless to blue, which is due to the formation of viologen radicals after photoinduced electron transfer (PIET) process. As we all know, the changed color is caused by the alteration of absorption intensity, ultimately impacting its luminescence as well. Thus, the bright and strong red fluorescence of this complex is quenched upon continuous UV light irradiation, which may be attributed to intramolecular energy transfer from the excited state of the europium ion to the colored state of the CV ligand. Based on the control of multiple colors of the complex, the designed encryption model can realize multiple anti-counterfeiting of real numbers. In addition, the conductivity of this compound increases significantly after UV illumination, showing excellent photo-modulated proton conductivity. In short, our work has proposed a multifunctional bipyridinium-based Ln-MOF with photochromism, photo-switchable photoluminescence and proton conduction, which offers valuable insights for the creation of versatile switchable materials based on MOFs. [Display omitted] • A novel viologen-based Eu-MOF exhibits reversible photochromism and photo-modulated photoluminescence. • The colored Eu-MOF presents higher proton conductivity after UV irradiation. • The Eu-MOF can be used for multiple anti-counterfeiting encryption of information. [ABSTRACT FROM AUTHOR]

[Display omitted] • A non-noble-metal plasmonic parabolic membrane with "pearl necklace" structure catalyst is prepared. • Light concentration is realized on basis of plasmonic effect and multiple reflection/absorption effect in parabolic curved surface. • The "pearl necklace" structures induce interface curvature effect for enhancement of water molecules transport process. The high-efficient utilization of sunlight is imperative to inducing a photocatalytic reaction, during which photo-induced electron–hole pairs participate in the redox reaction. The photo-electric effect is the basis for this reaction. The coupled use of sunlight, photo-electric effect and photo-thermal effect, is a significant guidance to realize light concentration, favoring the hydrogen production from water splitting. Here, we prepare an Sn/SnO 2-x @Ni-MOF catalyst, a non-noble-metal plasmonic parabolic membrane with a "pearl necklace" structure. The plasmonic thermal effect and unique parabolic curved surface of this catalyst allow concentrated solar energy and multiple light reflection/absorption to be achieved for the high-efficient utilization of sunlight. Furthermore, the Sn/SnO 2-x @Ni-MOF "pearl necklace" structure also improves photo-generated carriers' separation-transfer process by internal Schottky junction between Sn and SnO 2-x /Ni-MOF, and helps accelerate water molecules transport based on the interface curvature effect. As a result, a competent rate of 8800 μmol h−1 g−1 with apparent quantum yields of 22.1 % and 16.2 % is achieved at wavelengths of 380 and 420 nm, respectively, providing a promising route for utilizing hydrogen energy. [ABSTRACT FROM AUTHOR]

1 The dip coating of yield stress fluids was simulated at Bingham number below 1. 2 The effects of individual physical parameters and the lifting speed on the flow inside the bath were studied. 3 The relationship between flow region, velocity and shear stress of fluids in the bath were established. 4 The dimensionless film thickness can be well described by the Bingham number. The literature has treated the dip coating of yield stress fluids with the Bingham number (B i = τ c / K γ ˙ n , where τ c , K , γ ˙ and n are the yield stress, consistency factor, shear rate and power-law exponent, respectively.) being larger than 1, and has ignored the influence of shear-dependent component (K γ ˙ n). This work simulated the dip-coating process for various simple yield stress fluids with Bi numbers below 1, and showed the importance of yield stress and shear-dependent component for the hydrodynamics inside the bath as well as the film thickness. The yielded-unyielded boundaries as well as the profiles of flow velocity and shear stress were theoretically determined under final steady state. The main flow characteristics of drainage in the meniscus were captured. Under the negligible effect of surface tension on the film coating, a semi-empirical model of film thickness considering drainage effect is proposed with good prediction performance. [ABSTRACT FROM AUTHOR]

Abstract: Hydrothermal reaction of Zn/Cd salts, NaN3 and 4-cyanobenzoic acid via in situ [2+3] cycloaddition generated two blue-green photoluminescent coordination polymers [Zn(cptta)(H2O)] (1) and [Cd(cptta)(H2O)] (2) (H2cptta=5-(4′-carboxy-phenyl)tetrazole). When only metal ions are considered as nodes, 1 shows rare 5-connected Shubnikov plane topological type and 2 has unprecedented 10-connected {312.424.59} topological type. [Copyright &y& Elsevier]

Abstract: Hydrothermal reaction of copper(II) chloride with 2-hydroxypyrimidine generated double salt of [Cu2Cl(μ4-pymo)] (1) (Hpymo=hydroxylpyrimidine) while hydrothermal treatment of CuCl2, NaN3 and acetonitrile resulted in double salt of [Cu2(mtta)Cl] (2) (Hmtta=5-methyltetrazole) in which in situ [2+3] cycloaddition reactions of acetonitrile with azide formed mtta ligand. X-ray single crystal structural analyses revealed that 1 shows a two-dimensional layer formed by fusion of one-dimensional structural motifs. The two-dimensional layers in 1 are held together by C–H⋯Cl hydrogen bonds to form three-dimensional supramolecular array. Compound 2 has a three-dimensional framework constructed from ribbons and [Cu8Cl4]4+ units. Uncommon coordination modes of μ4-1,2κO:3κN:4κN′ pymo and μ4-Cl (Cl at the apex of a Cu4Cl square pyramid) in 1 and μ4-η1:η1:η1:η1 mtta in 2 were also observed. The short Cu(I)⋯Cu(I) distances were found in 1 and 2, indicating the existence of Cu(I)⋯Cu(I) interactions. [Copyright &y& Elsevier]

Abstract: Hydrothermal reaction of CuBr2, 4,4′-bipyridine and ethanol/methanol generated two copper (I) bromide complexes with in situ alkylated 4,4′-bipyridium, namely [C14H18N2][Cu5Br7] (1) and [C12H14N2][Cu4Br6] (2). The structure of 1 consists of chains and N,N′-diethyl-4,4′-bipyridinium. The underlying structural motif in of 1 is the Cu5Br capped square pyramid, which is different from the Cu5Br2 pentagonal bipyramidal structural motif in various documented anions. The in 1 contains untypical μ5-bromide, with which five copper atoms forms a capped square pyramid rather than a pentagonal pyramid as predicted by Subramanian and Hoffmann. Compound 2 is isostructural with [C12H14N2][Cu4Cl6] reported by Willett, and consists of chains and N,N′-dimethyl-4,4′-bipyridinium. The chain is composed of alternating Cu6Br6 and Cu2Br6 units. [Copyright &y& Elsevier]

Abstract: Hydrothermal reaction of molybdenum oxide and copper(II) source in the presence of 4,4′-bipyridine (4,4′-bpy) afforded three-dimensional covalent framework [CuII(4,4′-bpy)(MoO4)] (1), while reaction with 1,4-diazoniabicyclo[2,2,2]octane (DABCO) in place of 4,4′-bpy and addition of metal molybdenum resulted in one-dimensional chain-like compound . The copper in 1 is divalent and approximately shows trigonal bipyramidal geometry, while in 2 is monovalent and approximately shows T-shaped geometry. The structure of 1 has a three-dimensional pillar-layered framework constructed from bimetallic {CuMoO4} layers bridged by bifunctional ligand 4,4′-bpy. Interestingly, the {CuMoO4} layer in 1 consists of 16-membered {Cu4Mo4O8} rings and 8-membered {Cu2Mo2O4} rings, different from other reported {CuMoO4} layers. The structure of 2 consists a one-dimensional chain that is attached by peripheral {Cu(HDABCO)}2+ units. The chain is constructed from octamolybdates through common corners. [Copyright &y& Elsevier]

In this paper, the asymptotical synchronization of fractional-order complex neural networks with non-delayed and delayed couplings is investigated. By employing the Kronecker product technique and weighted norm, two Lyapunov functions are constructed. Based on the fractional-order Lyapunov direct method and Kronecker product method, together with the Laplace transform and the comparison principle, several novel sufficient conditions on synchronization of fractional-order complex neural networks with non-delayed and delayed couplings, respectively, are proposed. Finally, three numerical examples are given to show the effectiveness of our proposed theoretical results and the difference between our main result and some existing results in the literature. [ABSTRACT FROM AUTHOR]

This paper deals with the adaptive learning based recoil suppression control problem of deepwater drilling riser systems subject to parametric perturbations, platform heave motion, and friction resistance force of drilling fluid discharge. First, a stochastic configuration network based approximator is presented to predict the friction resistance force of drilling fluid discharge. Then, model reference adaptive learning recoil controllers are developed for the drilling riser system, and the existence condition and supporting algorithm are provided. Simulation results show that: (i) the designed stochastic configuration network approximator is efficient to predict the friction resistance of drilling fluid discharge on the riser; (ii) the presented model reference adaptive learning recoil controllers are effective to restrain the recoil response of the riser; (iii) compared with the existing recoil controllers, which are all based on the exact dynamic recoil control models, the model reference adaptive learning recoil controllers proposed in this paper are no longer constrained by the accuracy of recoil model; (iv) the model reference adaptive learning recoil controllers are more robust than the existing ones to the unmodeled dynamics, systematic uncertainty, and parametric perturbations, and have better transient performance of system thereby guaranteeing the safety of the drilling riser systems effectively. • A learning-based friction force predictor of drilling fluid discharge is designed. • Model reference adaptive learning recoil controllers are proposed for riser systems. • Adaptive recoil controllers are robust to unmodeled system dynamics and disturbances. [ABSTRACT FROM AUTHOR]

Abstract: Hydrothermal treatment of cobalt chloride, 2,2′-biimidazole (H2biim), oxalate acid and NaOH at 160°C for five days produced a three-dimensional mixed-valence metal-organic framework [CoIII(Hbiim)3]2[CoII 3(ox)3]·4H2O ( 1 ). Compound 1 exhibits a 3D network with tri-nodal (3-c)2(4-c)3 topology, in which [CoIII(Hbiim)3] building blocks as 3-connected nodes, and CoII ions as 4-connected nodes. The magnetic measurements reveal that compound 1 exhibits a spin canting antiferromagnetic coupling between adjacent CoII ions. [Copyright &y& Elsevier]

Human exposure to formaldehyde, toluene, xylene (FTX) and other volatile organic compounds (VOCs) are associated with negative health impact. To characterize the exposure and health effects of FTX and TVOC from indoor environments, we conducted an extensive monitoring campaign involving 1278 measurements of 472 indoor locations in Harbin, a megacity in China from May 2013 to March 2018. The results showed that household had the highest mean formaldehyde concentration (0.171 ± 0.084 mg m-3) among all types of indoor environments. Meanwhile, there was no significant differences in formaldehyde concentration of the living room, master bedroom, secondary bedroom and study room (p > 0.05), as well as toluene and xylene. The highest mean concentration of toluene, xylene and TVOC was measured in public bath center. Great difference was found between formaldehyde concentrations in 2013 and other years, except 2015. There were great positive nonlinear correlations between the indoor temperature and concentration of formaldehyde (p < 0.01), good negative nonlinear correlations between the finish time of decoration and concentration of formaldehyde (p < 0.01), good positive linear correlations between the relative humidity and concentration of formaldehyde (p < 0.01). A risk assessment methodology was utilized to evaluate the potential adverse health effects of the individual FTX compounds according to their carcinogenicities. The predicted carcinogenic risk of formaldehyde was greater than the threshold value 1E-06 at all environments. The non-carcinogenic risk of TX compounds in the population is negligible. For estimating human health risk exposure, sensitivity analysis showed that more attention should be given to the influential variables such as the level of pollutants. • SConducted an extensive monitoring campaign in Harbin, from May 2013 to March 2018. • There were correlations between the indoor temperature, relative humidity, finish time of decoration and concentration of formaldehyde. • The predicted carcinogenic risk of formaldehyde was greater than the threshold value at all microenvironments. [ABSTRACT FROM AUTHOR]

A 3D spin canted cupric MOF is constructed from the layered [Cu 2 Cl(tta) 2 ] n n− and chain-like [Cu(Itta)(I 0.25 tta) 2 ] n 2n− motifs linked by 5-Iodo-1- H -tetrazole from in situ C-H iodination of 1- H -tetrazole. • A novel 5- I -tetrazole based MOF has been prepared by the hydrothermal treatment of CuCl 2 , 1- H -tetrazole and HI acid. • The 5- I -tetrazole can be generated from the Direct C H in situ Iodination of 1- H -tetrazole. • The MOF exhibits spin canted antiferromagnetic couplings. Hydrothermal treatment of cupric chloride and tetrazole in the presence of hydroiodic acid generated a spin canted coordination polymer [Cu 3 (tta) 2 (Itta)(I 0.25 -tta) 2 Cl] (1), (Htta = 1- H -tetrazole, Itta = 5-Iodo-1- H -tetrazole), showing a 3D network constructed from layered [Cu 2 Cl(tta) 2 ] n n– and chain-like [Cu(Itta)(I 0.25 tta) 2 ] n 2n– moieties linked through expensive Itta groups in situ C H iodinated from cheap Htta. [ABSTRACT FROM AUTHOR]

Hydrothermal treatment of flexible linker 5,5′-(propane-1,3-diylbis(oxy)) diisophthalic acid (pdta) and LiOH generated a novel FL-MOF (flexible ligand based metal-organic framework) of conformational flexibility, showing gradual structural changes from 1D helical banded structure to 3D accordion-pleats-like network. Ultralight metal Li-based FL-MOF possesses hingelike movement of −O−(CH 2) 3 −O− flexible moieties on pdta linker, which resulted in large positive thermal expansion (PTE) behavior with volumetric expansion coefficient of 163.7860 MK−1. A novel accordion-pleats-like/windmill-like FL-MOF with conformational flexibility has been constructed from Li−O−Li based helical banded structure and V-shaped –−O−(CH 2) 3 −O− moiety based pdta linker, exhibiting large positive thermal expansion behaviour. Unlabelled Image • A novel Li(I)-based FL-MOF has been characterized by variable-temperature single-crystal X-ray diffraction. • The MOF performs gradual structural changes from 1D helical banded structure to 3D accordion-pleats-like network. • The MOF exhibits positive thermal expansion (PTE) with volumetric expansion coefficient of 163.7860 MK-1 • The PTE behavior was caused by the hingelike movement of −O−(CH 2) 3 −O− moieties and the short Li•••Li distance. [ABSTRACT FROM AUTHOR]

Graphical abstract (003)-facet-exposed Ni 3 S 2 nanoporous thin films with metallic property are developed on nickel foil and behave as bifunctional electrocatalysts toward alkaline water splitting. Nanoporous texture provides sufficient interfacial active sites and short mass transfer pathway for efficient electrolysis. The coordinatively unsaturated Ni 3 -triangle fragments of Ni 3 S 2 (003) facet have promotion effect on water dissociation. Highlights • (003)-facet-exposed Ni 3 S 2 thin films were synthesized by anodization and vapor-sulfurization methods. • The ultra-small hollow spheres provide hydrophilic/aerophobic surface and deliver abundant electrochemical active sites. • Exposed Ni 3 -triangles of Ni 3 S 2 (003) surface have promotion effect on water dissociation. • The binder-free architecture could facilitate charge transfer and improve electrochemical durability. Abstract Developing earth-abundant catalysts for overall water splitting is important to sustainable energy conversion technologies. However, selectively exposing active surface and judiciously optimizing nanostructure remain challenging for high-performance electrocatalysts. Herein, (003)-facet-exposed Ni 3 S 2 nanoporous thin films (NTFs) on nickel foil are synthesized through anodization and vapor-sulfurization strategies. The Ni 3 S 2 NTFs exhibit low onset overpotentials of 48 and 152 mV, and require overpotentials of 135 and 175 mV to achieve a benchmark of 10 mA cm–2 towards alkaline hydrogen and oxygen evolution, respectively. Remarkably, an electrolyzer assembled by Ni 3 S 2 NTFs as both anode and cathode can deliver a water-splitting current density of 10 mA cm–2 at 1.611 V. Experimental and theoretical results indicate that the controllable hollow nanoporous spheres and low-coordinated Ni 3 -triangles on Ni 3 S 2 (003) facet synergistically contribute to the electrocatalytic activity. [ABSTRACT FROM AUTHOR]

Abstract The highly efficient yet persistent hydrogen generation catalyzed by heterogeneous non-noble metal catalysts is emerging extensive application prospect in energy catalysis and transformation fields. Regrettably, the activity and stability of such catalysts often become the huge stumbling blocks for the catalytic hydrolysis of ammonia borane (NH 3 BH 3) to produce hydrogen. Herein, we report a facile and effective in-situ mosaic strategy for preparing non-noble metal and nitrogen co-doped mesoporous carbon catalysts, which feature homogeneously embedded, different sized metal nanoparticles as well as highly tunable nitrogen contents and types. Experimental results indicate that the Co@NMC-800-0.5 catalyst exhibits the highest catalytic activity for the hydrolysis of NH 3 BH 3 among all the synthesized catalysts, which can be attributed to the superhigh surface area, pore volume and large pore size (1044 m2/g, 2.131 cm3/g, 7.5–13.6 nm) of the support, as well as the modified electronic structure and chemical microenvironment of the metallic Co NPs. More practically, the Co@NMC-800-0.5 catalyst manifests a higher recyclability (up to reuse 10 times without significant loss of its catalytic activity) than those from directly supported Co NPs on N-doped mesoporous carbon, implying a superior recycling stability in the catalytic reaction. Highlights • Co@NMC-800-0.5 catalyst with superhigh surface area, pore volume and larger pore size. • The catalyst possesses a superior catalytic performance for hydrolysis of NH 3 BH 3. • The actual active species should be N-doped carbon embedded Co NPs. • Apparent activation energy of NH 3 BH 3 hydrolysis is as low as 41.6 ± 2 kJ/mol. • It manifests an excellent recyclability and without any deterioration. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Both subcooled liquid vapor pressure ( P L ) and octanol–air partition coefficient ( K OA ) are widely used as descriptors to predict gas-particle partitioning behavior of semi-volatile organic compounds (SVOCs), such as polybrominated diphenyl ethers (PBDEs). These two descriptors are functions of temperature, which are expressed as the Clausius-Clapeyron equations with the coefficients A L and B L for P L (log P L = A L + B L / T ) and A O and B O for K OA (log K OA = A O + B O / T ), where T is temperature in K. In this study, a simple equation to relate log K OA and log P L (log K OA = −log P L + 6.46) was derived, which also links the coefficients of A L & B L and A O & B O . Regression analysis of published data of internal energy Δ U OA for 22 PBDE congeners with their mole mass was made, leading a regression equation to calculate the internal energy for all 209 PBDE congeners. Three datasets of log K OA at 25 °C for all 209 PBDE congeners were evaluated; the one with the best match with experimentally measurements was selected. Using the datasets and equations described above, we calculated the values of Clausius-Clapeyron coefficients A O & B O and A L & B L for all 209 PBDE congeners at the following steps. First, B O was computed using the values of Δ U OA . Next, we calculated the values of A O using the values of B O and the values of log K OA at 25 °C. Finally, the values of the parameter A L and B L were determined for all 209 PBDE congeners. Results are in consistent with data available in the literature and the accuracy of the data were also evaluated. With these Clausius-Clapeyron coefficients, the values of P L and K OA at any environmentally relevant temperature can be calculated for all 209 PBDE congeners, and thus provides a quick reference for environmental monitoring and modeling of PBDEs. [ABSTRACT FROM AUTHOR]

[Display omitted] • A facile and efficient strategy is developed to prepare hierarchical porous catalyst. • Pd@CIL-900 features a superior catalytic performance for quinolines hydrogenation. • The quinolines hydrogenation is conducted under extremely mild conditions. • Apparent activation energy of quinoline hydrogenation is as low as 41.1 kJ/mol. Chemoselective hydrogenation of quinolines is often subjected to the problems of leaching and poisoning of catalytic active site as well as harsh reaction conditions. Developing a novel and high-performance heterogeneous catalyst is of paramount importance yet a huge challenge. Herein, we report a facile and efficient strategy for preparing the large surface area and highly N-doped hierarchical porous carbon anchored tiny Pd NPs catalyst, in which the low-cost chitosan, nitrogen-rich ionic liquids are served as composite precursors and KZ molten salt as friendly pore-forming agent. And a series of Pd@CIL-T (C refers to chitosan, IL refers to ionic liquid, T = 600–900 °C) catalysts are successfully fabricated via pyrolyzing aforesaid composites at different temperatures followed by anchoring the highly dispersed and small-sized Pd NPs on their surface. Among all the prepared catalysts, Pd@CIL-900 exhibits the optimal catalytic performance towards the selective hydrogenation of quinoline under extremely mild conditions (0.6 mol% Pd, 0.1 MPa H 2 and 50 °C). The kinetic experiments further reveal that such hydrogenation is subject to a pseudo-first order reaction and the apparent activation energy is as low as 41.1 kJ/mol, demonstrating excellent hydrogenation reaction rate. Moreover, the catalytic activity and selectivity are well maintained even after being reused for fifth reaction cycles. [ABSTRACT FROM AUTHOR]

Cyber-physical systems (CPSs), which are an integration of computation, networking, and physical processes, play an increasingly important role in critical infrastructure, government and everyday life. Due to physical constraints, embedded computers and networks may give rise to some additional security vulnerabilities, which results in losses of enormous economy benefits or disorder of social life. As a result, it is of significant to properly investigate the security issue of CPSs to ensure that such systems are operating in a safe manner. This paper, from a control theory perspective, presents an overview of recent advances on security control and attack detection of industrial CPSs. First, the typical system modeling on CPSs is summarized to cater for the requirement of the performance analysis. Then three typical types of cyber-attacks, i.e. denial-of-service attacks, replay attacks, and deception attacks, are disclosed from an engineering perspective. Moreover, robustness, security and resilience as well as stability are discussed to govern the capability of weakening various attacks. The development on attack detection for industrial CPSs is reviewed according to the categories on detection approaches. Furthermore, the security control and state estimation are discussed in detail. Finally, some challenge issues are raised for the future research. [ABSTRACT FROM AUTHOR]

Distributed cooperative control of multi-agent systems has been one of the most active research topics in the fields of automatic control and robotics. This paper provides a survey on recent advances in distributed cooperative control under a sampled-data setting, with special emphasis on the published results since 2011. First, some typical sampling mechanisms related to this topic, such as uniform sampling, nonuniform sampling, random sampling, and event-triggered sampling, are summarized in both asynchronous and synchronous paradigms. Then, based on different coordinated tasks, recent results on distributed sampled-data cooperative control of multi-agent systems are categorized into four classes, i.e., sampled-data leaderless consensus, sampled-data leader-following consensus, sampled-data containment control, and sampled-data formation control. For each class, some explicit research lines are identified according to various sampling mechanisms. In particular, depending on definitions of event triggering conditions, some representative event-triggered sampling mechanisms are sorted out and discussed in detail. Finally, several challenging issues for future research are proposed. [ABSTRACT FROM AUTHOR]