Drive-Response Synchronization of a Fractional-Order Hyperchaotic System and Its Circuit Implementation

A novel fractional-order hyperchaotic system is proposed; the theoretical analysis and numerical simulation of this system are studied. Based on the stability theory of fractional calculus, we propose a novel drive-response synchronization scheme. In order to achieve this synchronization control, the Adams-Bashforth-Moulton algorithm is studied. And then, a drive-response synchronization controller is designed to realize the synchronization of the drive and response system, and the simulation results are given. At last, the fractional oscillator circuit of the new fractional-order hyperchaotic system is designed based on the EWB software, and it is verified that the simulation results of the fractional-order oscillator circuit are consistent with the numerical simulation results through circuit simulation

Adaptive Pinning Synchronization Control of the Fractional-Order Chaos Nodes in Complex Networks

Adaptive pinning synchronization control is studied for a class of fractional-order complex network systems which are constructed depending on small-world network algorithm. Based on the fractional-order stability theory, the suitable adaptive control scheme is designed to guarantee global asymptotic stability of all the nodes in complex network systems and the node selected algorithm is given. In numerical implementation, it is shown that the numerical solution of the fractional-order complex network systems can be obtained by applying an improved version of Adams-Bashforth-Moulton algorithm. Furthermore, simulation results are provided to confirm the validity and synchronization performance of the advocated design methodology

Identification of Key Nodes in a Power Grid Based on Modified PageRank Algorithm

For avoiding the occurrence of large-scale blackouts due to disconnected nodes in the power grid, a modified PageRank algorithm is proposed to identify key nodes by integrating the topological information and node type. The node betweenness index is first introduced based on complex network theory, which is modified to reflect the node topological information in the power grid. Then, according to the characteristics of different node types in the power grid, a modified PageRank algorithm is proposed to rapidly identify key nodes, which takes the generator nodes, load nodes, and contact nodes into account. IEEE 39-Bus system and IEEE 118-Bus system are used for the simulations. Simulation results showed that the network transmission efficiencies of the power grid are reduced from 64.23% to 5.62% and from 45.4% to 5.12% in the two simulation systems compared with other methods. The proposed identification algorithm improved the accuracy, and a provincial power grid simulation system in China is used to verify the feasibility and validity. The identified nodes are removed, which split the power grid according to importance index values. The proposed method in this paper is helpful to prevent the occurrence of cascading failure in the power system, and it can also be used to power systems with renewable energy sources and an AC/DC hybrid power grid

Fractional-Order Hyperbolic Tangent Sliding Mode Control for Chaotic Oscillation in Power System

Chaotic oscillation will occur in power system when there exist periodic load disturbances. In order to analyze the chaotic oscillation characteristics and suppression method, this paper establishes the simplified mathematical model of the interconnected two-machine power system and analyzes the nonlinear dynamic behaviors, such as phase diagram, dissipation, bifurcation map, power spectrum, and Lyapunov exponents. Based on fractional calculus and sliding mode control theory, the fractional-order hyperbolic tangent sliding mode control is proposed to realize the chaotic oscillation control of the power system. Numerical simulation results show that the proposed method can not only suppresses the chaotic oscillation but also reduce the convergence time and suppress the chattering phenomenon and has strong robustness

A review of underwater inductive wireless power transfer system

Abstract The IPT system has been studied for underwater applications such as autonomous underwater vehicles (AUVs) and subsea sensors. However, it rarely comparatively shows the performance of the IPT system in air, freshwater, and seawater. Based on the fore‐mentioned research background, this paper presents a survey of the properties of the IPT system in different mediums. Here, a 100 W power‐level experimental IPT prototype is built and tested. The resonant frequency is set at 300 kHz with a gap range from 10 to 190 mm. The comparison is focused on the efficiency, mutual inductance, coupling coefficient, coil resistance, and quality factor of the IPT system. The IPT system is placed in air, freshwater, and seawater with the same settings. What's more, the magnetic fields of coupling coils in air, freshwater, and seawater are presented in this paper. This paper could be acted as a reference to optimize the IPT system and facilitate future IPT research for underwater applications by analysing the performance of the IPT system in different mediums. The 3D Ansys Maxwell simulation of the IPT system is also given here to study the magnetic fields

Polymerization of α‑Olefins Using a Camphyl α‑Diimine Nickel Catalyst at Elevated Temperature

Chiral (1<i>S</i>)- and (1<i>R</i>)-camphyl α-diimine nickel complexes were synthesized respectively with (1<i>S</i>)-(+) camphorquinone and (1<i>R</i>)-(−) camphorquinone as raw reagents and used as catalyst precursors for olefin polymerizations. It is found that the ligand chirality has no influence on catalytic activity and regioselectivity for olefin polymerizations. Ethylene, propylene, 1-hexene, and 4-methyl-1-pentene polymerizations with the camphyl α-diimine nickel activated by AlEt₂Cl can exhibit some living characteristics under the optimized conditions. The resultant polypropylenes and poly­(1-hexene)­s have significantly narrow molecular weight distributions (PDI < 1.2) in a wide temperature range, even at an elevated temperature of 70 °C. Sustainable period of the linear relationship of <i>M</i>_n vs polymerization time depends on temperature for propylene and 1-hexene polymerizations. Additionally, high 1,3-enchainment fraction of 45% is observed even at −60 °C for propylene polymerization using the camphyl α-diimine catalyst due to 2,1-insertion of propylene and chain walking

Ligand-Directed Regioselectivity in Amine–Imine Nickel-Catalyzed 1‑Hexene Polymerization

1-Hexene polymerizations were carried out with amine–imine nickel complexes [(ArNC­(R¹)–(R²R³)­CNHAr)­NiBr₂, <b>1a</b>, R¹ = R² = R³ = Me, Ar = 2,6-(iPr)₂C₆H₃; <b>1b</b>, R¹ = R² = R³ = Me, Ar = 2,6-(Me)₂C₆H₃; <b>2a</b>, R¹ = Me, R² = R³ = H, Ar = 2,6-(iPr)₂C₆H₃; <b>3a</b>, R¹ = Me, R² = <i>t</i>Bu, R³ = H, Ar = 2,6-(iPr)₂C₆H₃] in the presence of MMAO or Et₂AlCl. The ligand-directed regioselectivity involving insertion fashion and chain walking in amine–imine nickel-catalyzed 1-hexene polymerization is clearly observed. Catalyst <b>1a</b> with two methyl substituents on the bridging carbon can polymerize 1-hexene to afford semicrystalline “polyethylene” with long methylene sequence (−(CH₂)<i>_n</i>–, <i>n</i> = 40–74) via a combination of 90% selectivity of 2,1-insertion fashion and precise chain walking, whereas catalyst <b>3a</b> with a <i>tert</i>-butyl on the bridging carbon can polymerize 1-hexene in 80% selectivity of 1,2-insertion to produce amorphous polyolefin with predominant methyl branches through 2,6-enchainment

NTIRE 2019 Challenge on Real Image Super-Resolution: Methods and Results

This paper reviewed the 3rd NTIRE challenge on single-image super-resolution (restoration of rich details in a low-resolution image) with a focus on proposed solutions and results. The challenge had 1 track, which was aimed at the real-world single image super-resolution problem with an unknown scaling factor. Participants were mapping low-resolution images captured by a DSLR camera with a shorter focal length to their high-resolution images captured at a longer focal length. With this challenge, we in-troduced a novel real-world super-resolution dataset (Re-alSR). The track had 403 registered participants, and 36 teams competed in the final testing phase. They gauge the state-of-the-art in real-world single image super-resolution