Mathematical control of complex systems 2013

Mathematical control of complex systems have already become an ideal research area for control engineers, mathematicians, computer scientists, and biologists to understand, manage, analyze, and interpret functional information/dynamical behaviours from real-world complex dynamical systems, such as communication systems, process control, environmental systems, intelligent manufacturing systems, transportation systems, and structural systems. This special issue aims to bring together the latest/innovative knowledge and advances in mathematics for handling complex systems. Topics include, but are not limited to the following: control systems theory (behavioural systems, networked control systems, delay systems, distributed systems, infinite-dimensional systems, and positive systems); networked control (channel capacity constraints, control over communication networks, distributed filtering and control, information theory and control, and sensor networks); and stochastic systems (nonlinear filtering, nonparametric methods, particle filtering, partial identification, stochastic control, stochastic realization, system identification)

Fuzzy-logic-based control, filtering, and fault detection for networked systems: A Survey

This paper is concerned with the overview of the recent progress in fuzzy-logic-based filtering, control, and fault detection problems. First, the network technologies are introduced, the networked control systems are categorized from the aspects of fieldbuses and industrial Ethernets, the necessity of utilizing the fuzzy logic is justified, and the network-induced phenomena are discussed. Then, the fuzzy logic control strategies are reviewed in great detail. Special attention is given to the thorough examination on the latest results for fuzzy PID control, fuzzy adaptive control, and fuzzy tracking control problems. Furthermore, recent advances on the fuzzy-logic-based filtering and fault detection problems are reviewed. Finally, conclusions are given and some possible future research directions are pointed out, for example, topics on two-dimensional networked systems, wireless networked control systems, Quality-of-Service (QoS) of networked systems, and fuzzy access control in open networked systems.This work was supported in part by the National Natural Science Foundation of China under Grants 61329301, 61374039, 61473163, and 61374127, the Hujiang Foundation of China under Grants C14002 andD15009, the Engineering and Physical Sciences Research Council (EPSRC) of the UK, the Royal Society of the UK, and the Alexander von Humboldt Foundation of Germany

State estimation for discrete-time neural networks with Markov-mode-dependent lower and upper bounds on the distributed delays

Copyright @ 2012 Springer VerlagThis paper is concerned with the state estimation problem for a new class of discrete-time neural networks with Markovian jumping parameters and mixed time-delays. The parameters of the neural networks under consideration switch over time subject to a Markov chain. The networks involve both the discrete-time-varying delay and the mode-dependent distributed time-delay characterized by the upper and lower boundaries dependent on the Markov chain. By constructing novel Lyapunov-Krasovskii functionals, sufficient conditions are firstly established to guarantee the exponential stability in mean square for the addressed discrete-time neural networks with Markovian jumping parameters and mixed time-delays. Then, the state estimation problem is coped with for the same neural network where the goal is to design a desired state estimator such that the estimation error approaches zero exponentially in mean square. The derived conditions for both the stability and the existence of desired estimators are expressed in the form of matrix inequalities that can be solved by the semi-definite programme method. A numerical simulation example is exploited to demonstrate the usefulness of the main results obtained.This work was supported in part by the Royal Society of the U.K., the National Natural Science Foundation of China under Grants 60774073 and 61074129, and the Natural Science Foundation of Jiangsu Province of China under Grant BK2010313

Superconducting diode effect in inversion symmetry breaking MoTe2 Josephson junctions

The superconducting diode effect (SDE) with nonreciprocal supercurrent transport has attracted considerable attention in recent years, both for its intriguing physics and for its potential applications in superconducting circuits. This study shows that planar Josephson junctions (JJs) based on type-II Weyl semimetal (WSM) MoTe2 can exhibit a prominent SDE due to the emergence of asymmetric Josephson effect (AJE) in perpendicular magnetic fields. As a result of the AJE, the critical supercurrents Ic are very asymmetrical regarding the current direction [/Delta]Ic. [/Delta]Ic can also be modulated effectively by an external magnetic field. As a result of the inversion symmetry breaking in WSM, all these results are in agreement with theoretically predicted intrinsic AJEs. The field-tunable AJE allows us to demonstrate the rectification of supercurrent in such MoTe2 JJs, with rectification efficiency up to 17%, paving the way for their application in superconducting electronics

Intrinsic Percolative Superconductivity in KxFe2-ySe2 Single Crystals

Magnetic field penetration and magnetization hysteresis loops (MHLs) have been measured in KxFe2-ySe2 single crystals. The magnetic field penetration shows a two-step feature with a very small full-magnetic-penetration field (Hp1= 300 Oe at 2 K), and accordingly the MHL exhibits an abnormal vanishing of the central peak near zero field below 13 K. The width of the MHL in KxFe2-ySe2 at the same temperature is in general much smaller than that measured in the relatives Ba0.6K0.4Fe2As2 and Ba(Fe0.92Co0.08)2As2, and the MHLs in the latter two samples show the normal central peak near zero field. All these anomalies found in KxFe2-ySe2 can be understood in the picture that the sample is percolative with weakly coupled superconducting islands.Comment: 5 page, 4 figure

An Optimal Backoff Time-Based Internetwork Interference Mitigation Method in Wireless Body Area Network

When multiple Wireless Body Area Networks (WBANs) are aggregated, the overlapping region of their communications will result in internetwork interference, which could impose severe impacts on the reliability of WBAN performance. Therefore, how to mitigate the internetwork interference becomes the key problem to be solved urgently in practical applications of WBAN. However, most of the current researches on internetwork interference focus on traditional cellular networks and large-scale wireless sensor networks. In this paper, an Optimal Backoff Time Interference Mitigation Algorithm (OBTIM) is proposed. This method performs rescheduling or channel switching when the performance of the WBANs falls below tolerance, utilizing the cell neighbour list established by the beacon method. Simulation results show that the proposed method improves the channel utilization and the network throughput, and in the meantime, reduces the collision probability and energy consumption, when compared with the contention-based beacon schedule scheme

Facile synthesis of zinc-based organic framework for aqueous Hg (II) removal: Adsorption performance and mechanism

Mercury (Hg) ions can lead to a serious impact on the environment; therefore, it was necessary to find an effective method for absorbing these toxic Hg ions. Here, the adsorbent (Zn-AHMT) was synthesized from zinc nitrate and 4-amino-3-hydrazine-5-mercapto-1,2, 4-triazole (AHMT) by one-step method and, characterized the microstructure and absorption performance by fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Thermal Gravimetric Analyzer (TGA) and X-ray photoelectron spectroscopy (XPS). Through a plethora of measurements, we found that the maximum adsorption capacity was 802.8 ​mg/g when the optimal pH of Zn-AHMT was 3.0. The isothermal and kinetic experiments confirm that the reaction process of Zn-AHMT was chemisorption, while the adsorption process conforms to the Hill model and pseudo second order kinetic model. Thermodynamic experiments showed that the adsorption process was spontaneous and exothermic. Selective experiments were performed in the simulated wastewater containing Mn, Mg, Cr, Al, Co, Ni, Hg ions. Our results showed that the Zn-AHMT has a stronger affinity for Hg ions. The removal rate of Zn-AHMT remained above 98%, indicating that the Zn-AHMT had a good stability validated by three adsorption-desorption repeatable tests. According to the XPS results, the adsorption reaction of Zn-AHMT was mainly attributed to the chelation and ion exchange. This was further explained by both density functional theory (DFT) calculation and frontier molecular orbital theory. We therefore propose the adsorption mechanism of Zn-AHMT. The adsorption reaction facilitates via the synergistic action of S and N atoms. Moreover, the bonding between the adsorbent and the N atom has been proved to be more stable. Our study demonstrated that Zn-AHMT had a promising application prospect in mercury removal

The effect of Aspergillus niger as a dietary supplement on blood parameters, intestinal morphology, and gut microflora in Haidong chicks reared in a high altitude environment

Aim: The effects of the inclusion of Aspergillus niger in the diet of Haidong chicks reared in the Qing-Zang high altitude area (China) under hypoxic conditions. Materials and Methods: A total of 720 Haidong chicks were randomly divided into six groups and fed diets supplemented with 0%, 0.5%, 0.75%, 1.0%, 1.25%, and 1.5% of A. niger to determine blood parameters, intestinal morphology, and gut microflora in Haidong chicks reared in a high altitude environment. Results: Packed cell volume (PCV), red blood cell (RBC) count, white blood cell count, and hemoglobin concentration increased in the groups fed diets containing A. niger. The administration of A. niger in 1.0% and 1.25% significantly decreased the concentration of Escherichia coli in the cecum, while the concentration of Bifidobacterium and Lactobacillus in the cecum and ileum was increased in the treated groups. When compared to the control groups, villi height, crypt depth, and goblet cell density in the intestine was raised, in general, in the groups treated with A. niger. Conclusion: These findings suggest that 1.25% A. niger as dietary supplement may improve the resistance to ascites among birds reared under hypoxic conditions

Fe₃S₄ nanoparticles for arterial inflammation therapy: Integration of magnetic hyperthermia and photothermal treatment

Photothermal therapy (PTT), based on nanoparticles, has been widely explored in the treatment of multiple diseases. However, limited by laser penetration ability, its treatment efficiency can be reduced when treating deep arterial inflammation, which is the major cause of atherosclerosis and vessels stenosis. Magnetic hyperthermia (MHT) has the outstanding tissue permeability, while its magnetothermal efficiency was relatively poor. In this study, Fe₃S₄ nanoparticles (NPs) were synthesized and characterized, and its dual capacity to convert light and magnetic stimulation into heat was confirmed. The Fe₃S₄ NPs also presented superior biocompatibility and great T2 weighted magnetic resonance imaging properties (52.8 mM^{-1} S^{-1}. Besides, its excellent effect in ablating inflammatory macrophages combining PTT and MHT was verified in vitro. In vivo experiment on Apo E-/- mice models exhibited that PTT combined with MHT could effectively eliminate infiltrating inflammatory macrophages and further inhibit the formation of arterial stenosis. This study concludes that the integration of PTT and MHT based on Fe₃S₄ NPs can serve as an effective therapeutic strategy for the treatment of atherosclerosis and vessels stenosis