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Changes in the water flow field will occur around bridge piers, leading to local scouring. When pipelines intersect bridge piers, this kind of scour may cause pipeline exposure or even suspension, ...

Emerging evidence indicates that blood–retinal barrier (BRB) damage is the main cause of diabetic retinopathy (DR), and the downregulation of tight proteins (TJs) located between endothelial cells and the activation of NLRP3 inflammasome-mediated inflammation in Müller cells result in BRB injury. In this study, we aimed to study the protective effect of lychee seed polyphenol (LSP) on BRB integrity and the mechanism of action. By establishing a cellular model of BRB injury by using high glucose (HG)-induced hRECs or co-culture system of hRECs with MIO-M1 cells, we found that LSP significantly maintained the integrity of monolayer of hRECs as revealed by the decreased PD40 permeability and increased TJs, including ZO-1, Occludin, and Claudin 5. In addition, LSP inhibited the NLRP3 inflammasome activation and the levels of inflammatory cytokines via the TLR4/MYD88/NF-κB pathway. Collectively, this study provides valuable insight into the utilization of LSP in the treatment of DR.

This paper focuses on the finite-time consensus tracking control problem of nonlinear multi-agent systems. Dynamics of each agent has completely unknown nonlinear terms that cannot be directly used...

This paper investigates the design problem of fuzzy dynamic output feedback $H_\infty $ controller for nonlinear networked systems via mismatched membership functions and adaptive event-triggered (AET) mechanism. Firstly, an AET mechanism is introduced to save communication resources, which causes the controller and the original system's premise variables to be asynchronous. Then, considering the influence of AET and mismatched membership functions, a model of fuzzy control system is established. In addition, utilizing the Lyapunov-Krasovskii(L-K) functional, sufficient conditions for the global exponential stability of the closed-loop system with $H_\infty $ performance are derived. Besides, the controller parameters and event-triggered (ET) weight matrix are solved by a set of linear matrix inequalities (LMIs). Finally, an example is given to demonstrate the effectiveness of the proposed control method.

In this paper, the problem of secure state estimation for cyber physical systems (CPSs) with state delay and sparse sensor attacks is studied. An algorithm combining set cover approach and adaptive switching mechanism is proposed, which can realize off-line acquisition of candidate set and accurately locate the real attack mode. The contributions of this algorithm are that it can greatly reduce the search space, eliminate the impact of attacks on state estimation, improve the estimation speed and ensure the real-time performance of state estimation under the premise of effective estimation. The sufficient condition for the existence of the observer is obtained. Finally, the rapidity and effectiveness of the designed observer are verified by two examples.

The viscosity of high Fe-containing hypereutectic Al–Si alloys was studied by using a high-temperature Searle-type rheometer. The results show that the steady-state viscosity of Al–17Si–(2,3,4) Fe alloy melts increases with the increase of iron content. During the continuous cooling of Al–17Si–(2,3,4) Fe alloy melts, the transient viscosity increases slowly at the initial stage of cooling. When the temperature decreases to a critical value, the transient viscosity increases abruptly. In the cooling process of Al–17Si–2Fe–(0,0.4,0.8)Mn alloy melts, the steady-state viscosity continues to increase and reach the maximum value firstly, then decreases abruptly, and then continues to increase again. The steady-state viscosity of Al–17Si–2Fe, Al–17Si–2Fe–0.4Mn and Al–17Si–2Fe–0.8Mn alloy melts experiences a sudden decrease at 630°C, 640°C and 670°C respectively due to the settlement of Fe-rich phases. The maximum value of viscosity of the Al–17Si–2Fe–(0,0.4,0.8)Mn alloy melts is increased with the increa...

The adaptive tracking control strategy is investigated for a class of multi-input and multi-output pure-feedback nonlinear delayed systems with unknown dead-zone inputs. This problem is challenging...

This paper investigates observer-based adaptive fuzzy control for a class of delayed nonlinear systems in pure-feedback form. We first proposed a linear observer to get the estimation of the system's state. And then utilise fuzzy logic systems to model those nonlinearities. Further, adaptive fuzzy approach and backstepping technique are combined to develop the desired controller via Lyapunov analysis. The suggested adaptive fuzzy control scheme ensures that all the signals of the resulting nonlinear system converge to a small neighbourhood of the origin. Then a real simulation is used to illustrated the effectiveness of our results.

The coagulation process by ferrous sulfate was used to pretreat coking wastewater prior to a subsequent biological treatment. The central composite Box–Behnken experimental design and response surface method were applied to evaluate and optimize the interactive effects of three operating variables, namely the initial pH, dosage of ferrous sulfate, and interaction time, on the physical and chemical performances of coagulation. Four dependent parameters, namely COD removal, cyanide removal, sulfide removal, and total oil removal, were either directly measured or calculated as responses. According to analysis of variances results, the four models proposed in this work can be used to navigate the design space, with the high regression coefficient R2 varying from 0.9158 to 0.9877. The initial pH, ferrous sulfate dosage, and interaction time had significant effects on the COD removal, cyanide removal, sulfide removal, and total oil removal due to their respective effects on chemical precipitation and co...

This paper revisits the stability problem for linear systems with time-varying delay and provides new stability conditions in terms of linear matrix inequalities (LMIs). The basic idea is the use of complete Lyapunov-Krasovskii functional (LKF) method and the derivation employs the discretization technique and the reciprocally convex combination. The main feature of this work lies in that the present result not only leads to some improvements over existing results in the LMI framework but also is applicable for time-delay systems with unstable delay-free case. A numerical example is given to show the effectiveness and merits of the present result.

This paper is concerned with the problem of adaptive fuzzy output tracking control for a class of nonlinear pure-feedback stochastic systems with unknown dead-zone. Fuzzy logic systems in Mamdani type are used to approximate the unknown nonlinearities, then a novel adaptive fuzzy tracking controller is designed by using backstepping technique. The control scheme is systematically derived without requiring any information on the boundedness of dead-zone parameters (slopes and break-points) and the repeated differentiation of the virtual control signals. The proposed adaptive fuzzy controller guarantees that all the signals in the closed-loop system are bounded in probability and the system output eventually converges to a small neighbourhood of the desired reference signal in the sense of mean quartic value. Simulation results further illustrate the effectiveness of the proposed control scheme.

This article deals with the problem of H ∞ filter design for nonlinear discrete-time systems with norm-bounded parameter uncertainties and time-varying delays. A new Lyapunov function and free-weighting matrix method are used for filtering design, consequently, a delay-dependent design method is first proposed in terms of linear matrix inequalities, which produces a less conservative result. Finally, numerical examples are given to demonstrate the effectiveness and the benefits of the proposed method.

This paper considers the problems of determining the stability and computing the bounds for maintaining the stability of limit cycles of linear systems under relay feedback. It derives a stability criterion and presents a region such that every trajectory starting from this region will converge to the limit cycle. The deduction is based on the estimation on the Poincare map which appears as a non-linear function.

This paper considers the robust stabilization problem for linear continuous-time descriptor systems with norm-bounded perturbations in matrix E . We show that if the problem has a solution, then the perturbations must not increase the rank of E . Under the assumption that the rank of E with uncertainties is always equal to the rank of E without uncertainties, the problem under consideration falls into two cases. For the first case, a complete solution in terms of a necessary and sufficient condition is given for quadratic stabilization. For the other case, a necessary condition and a sufficient condition are presented.

(2000). H8 control for linear systems with additive controller gain variations. International Journal of Control: Vol. 73, No. 16, pp. 1500-1506.

This paper considers the structural stability problem for a class of descriptor systems with interval plants. It first derives a norm bound for uncertain descriptor systems to be impulse-free (regular) and stable (i.e. structurally stable). Then, a necessary and sufficient condition for the uncertain linear descriptor systems with interval plants to be structurally stable is established. A numerical example is presented to illustrate the use of the result.

A mathematical model based on a two-parameter mechanism for reverse osmosis in a unstirred batch system has been theoretically developed and analyzed numerically. The model consists of a convective salt flux across the membrane and a salt diffusion equation which contains a nonlinear convective term with a moving boundary and which is solved by a finite difference procedure. A computer-aided analysis of the proposed model was compared with the analytical results of the different models available in the literature. It is found that the model proposed is in better agreement with the experimental data obtained by many investigators in the past.

Transport behavior across a membrane in a reverse osmosis unstirred batch system is analyzed by simulation of a mathematical model developed in a previous paper. The effects of a phenomenon termed “concentration polarization” on the throughput rate and on % SR are postualted by information generated. A simple determination method of the membrane constants via the model simulation is proposed.

A mathematical model based on two characteristic membrane parameters, A and B, is developed to describe the transport phenomena in the reverse osmosis process of the composite membrane, which consists of two components having different value of A and B. It is found possible to fabricate a high performance membrane by casting a film composed of a dispersed phase with a small particle size of Component II possessing a high water flow (i.e., large value of A) and a very thin matrix phase of Component I possessing a small solute permeation (i.e., small value of B) in the practical separation technique.