Fault-tolerant control design for unreliable networked control systems via constrained model predictive control.

This work deals with the problem of passive fault-tolerant control (FTC) for discrete-time networked control systems (NCSs). Network imperfections such as random time delay and packet dropout are modeled as a Markov chain that results in a Markovian jump linear system (MJLS). Some of the elements in the transition probability matrix (TPM) are supposed to be unknown so as to address network complexities. In addition, a comprehensive and practical fault model that considers the stochastic nature of networks is employed. By utilizing this fault model, the closed-loop NCS model is obtained by means of state augmentation technique. Then, a constrained model predictive control (MPC) is proposed to develop a fault-tolerant control strategy in which all these issues are considered as well as input constraint. Sufficient conditions to design the proposed reliable controller are derived in terms of linear matrix inequalities (LMIs). Finally, two examples are utilized to demonstrate the validity of the proposed FTC. The simulation results show that the proposed strategy works well, and results in more effective responses compared to state-of-the-arts studies.

Different land uses influenced on characteristics and distribution of microplastics in Qarasu Basin Rivers, Gorgan Bay, Caspian Sea.

Concerns about the negative effects of microplastics (MPs) on human health have led to increasing attention to the occurrence of MPs in the aquatic environment. Recent studies have focus on the spatio-temporal distribution of MPs in rivers for residential and agricultural areas. Qarasu River Basin, watershed to Gorgan Bay, is the site of many permanent rivers and the levels of MP pollution in those rivers are unknown. This research was conducted in three different types of land use: forest, residential, and agricultural along 8 different rivers. A total of 9 fish species were identified and the presence of MPs in 87% of fish was confirmed. The prevalence of MP among species was Liza sp. > Carassius gibelio > Gambusia holbrooki > Rutilus rutilus > Neogobius melanostomus > Cyprinus carpio = Vimba vimba > Rutilus frisii > Barbus sp. The highest frequency of MPs was observed in Qarasu River (1880 ± 251 n/kg) and Mohammadabad River (184 ± 1340 n/kg) in agricultural land use, and the lowest frequency was related to Baghu and Ziarat Rivers with 660 ± 77 and 600 ± 91 n/kg found in forest land use respectively. The highest type, color, and size of MP sediments were fragment, black, and 1-2 mm, respectively. The highest type, color, and size of MP in fishes were fiber, black, and 0.5-0.1 mm respectively. Overall according to the source tracing result, agricultural land use was the main source of MP pollution of Gorgan Bay. The Bay is strongly affected by the incoming rivers, the Qarasu River Basin as the most important river supplying water.