Summary
This article investigates the event‐triggered finite‐time reliable control problem for a class of Markovian jump systems with time‐varying transition probabilities, time‐varying actuator faults, and time‐varying delays. First, a Luenberger observer is constructed to estimate the unmeasured system state. Second, by applying an event‐triggered strategy from observer to controller, the frequency of transmission is reduced. Third, based on linear matrix inequality technique and stochastic finite‐time analysis, event‐triggered observer‐based controllers are designed and sufficient conditions are given, which ensure the finite‐time boundedness of the closed‐loop system in an H∞ sense. Finally, an example is utilized to show the effectiveness of the proposed controller design approach.
In this article, a performance-guaranteed containment control scheme based on reinforcement learning (RL) algorithm is proposed for a class of pure-feedback multi agent systems (MASs) with unmeasurable states. The unknown nonlinear functions are approximated by the neural networks (NNs) and an adaptive NN state observer is designed for the states estimation. Based on estimated states, the algebraic loop problem can be removed by introducing filtered signals, and the actor-critic architecture of RL algorithm is employed to acquire the optimal controller in the framework of backstepping. Different from many optimal strategies, this article proposes a simpler mechanism based on the uniqueness of the optimal solution to obtain the actor and critic updating laws instead of gradient descent algorithm with complicated calculation. In addition, predefined performance function and an improved error transformation technique are utilized to guarantee the containment error within a prescribed boundary. By using Lyapunov stability theory and graph theory, the stability of the closed-loop system can be demonstrated. Finally, the effectiveness of the method proposed in this article is verified by a simulation example.
Summary
This paper proposes a self‐triggered (ST) adaptive prescribed‐time tracking control method for a class of stochastic nonlinear systems. Different from the existing results, an improved ST mechanism is proposed by adding a judgment condition to reduce the negative effect of excessive design interval on system performance. Based on the one‐to‐one mapping and backstepping technique, an adaptive prescribed‐time tracking control method is proposed, which can make the error converge to the predefined precision set within the predetermined time. Simultaneously, applying the Lyapunov stability method, the boundedness of all signals in the closed‐loop system can be ensured. Finally, a detailed simulation example is provided to show the effectiveness of the proposed control strategy.
A total of 30 microsatellite markers were isolated from miiuy croaker, Miichthys miiuy, and characterized. Of these, 24 were polymorphic with an average of 4.33 alleles per locus (range: 2-8). The observed (H o ) and expected (H e ) heterozygosities ranged from 0.0667 to 1.0000 (mean: 0.6361) and 0.3828 to 0.8139 (mean: 0.6443), respectively. The mean polymorphism information content (PIC) value was 0.576, ranging from 0.348 to 0.823. Eight loci deviated significantly from the Hardy-Weinberg equilibrium (HWE). Twelve of the 30 primer pairs amplified DNA sequences of large yellow croaker, Pseudosciaena crocea, and 10 were polymorphic. Except for MM007, sequence alignments of microsatellite flanking regions of the other 11 loci were highly similar between the two species. The gynogenetic P. crocea induced by the sperm of M. miiuy were verified using four cross-amplified primer pairs. No specific paternal bands were found in the offspring, indicating exclusive maternal inheritance.
Accurately defining the peak ages and timescales of high‐temperature metamorphism is fundamental to unravelling tectonic dynamics. However, metamorphic constraints are frequently hampered by a large spread of zircon U–Pb ages without explicit textural relationships. Integrated garnet and zircon petrochronology may clarify ambiguous ages retrieved from ancient high‐temperature metamorphic rocks. There is a long‐standing debate on the interpretation of the spread of zircon ages from c. 2.5–1.8 Ga for the granulites of the North China Craton. In order to clarify the timing and duration of (ultra)high‐temperature metamorphism in the North China Craton, we investigated a mafic granulite and the adjoining gneiss from the Yinshan Block of the North China Craton using zircon and titanite U–Pb geochronology combined with garnet Lu–Hf and Sm–Nd geochronology. Pseudosection modelling and conventional thermobarometric calculations constrain the peak metamorphic conditions to be ~1.0 GPa and ~850°C. The near‐complete lack of major‐element zoning in garnet, aside from ~2 μm diffusion profiles at crystal rims, suggests complete re‐equilibration at peak temperatures followed by fast cooling from high temperatures. The Lu–Hf garnet age of 1870 ± 4 Ma and Sm–Nd age of 1870 ± 7 Ma, determined on the same garnet fractions, are indistinguishable from the zircon U–Pb age of 1866 ± 11 Ma obtained from zircon that grew contemporaneously with garnet, evidenced by the chemical equilibrium of coexisting garnet and zircon, and are additionally consistent with a titanite U–Pb age of 1876 ± 7 Ma. We interpret this close agreement of ages, within uncertainty, coupled to the existence of flat Sm–Nd–Hf profiles in garnet that also has well‐preserved Lu zoning, to reflect a short‐lived high‐temperature metamorphic event that was terminated by rapid exhumation and cooling. The short‐lived (<4 Myr) high‐temperature metamorphism may be generated in the lowermost parts of the crust through magmatic underplating/intraplating during extension that follows collision of the Ordos and the Yinshan Blocks.
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