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A new dual‐motor servo steering system with improved reliability and safety is proposed. But, despite the advantages of the proposed servo system, it is strongly coupled, non‐linear and multivariable, where the biggest challenge lies in its tracking and synchronization control. To improve the tracking and synchronization control performance of the proposed servo system, a tracking and synchronization control strategy based on backstepping super‐twisting control and multi‐level differential coupling is presented. First, a parallel model of the dual‐motor is established. Then, backstepping and super‐twisting control algorithms are integrated while adaptively optimizing key parameters to ensure the robustness and tracking performance of each motor. After that, an angular synchronization controller with multi‐level differential coupling and backstepping super‐twisting algorithm is proposed to compensate for the synchronization error of the dual‐motor system caused by parameter uncertainty. Finally, the simulation is carried out using Simulink to verify the effectiveness of the proposed control strategy. This paper proposes an adaptive multi‐level differential coupling control strategy to improve the synchronization accuracy of dual motors under external loads and disturbances by integrating the global backstepping theory and the super twisting theory. [ABSTRACT FROM AUTHOR]

High precision control is often accompanied by many control parameters, which are interrelated and difficult to adjust directly. It is difficult to convert the system control effect directly into mathematical expression, so it is difficult to optimize it by intelligent algorithm. To solve this problem, we propose an improved sinusoidal gray wolf optimization algorithm (ISGWO). In this algorithm, a particle crossing processing mechanism based on the symmetry idea is introduced to maximize the retention of the position information of the optimal individual and improve the search accuracy of the algorithm. In addition, a differential cross-perturbation strategy is adopted to help the algorithm jump out of the local optimal solution in time, which enhances the development capability of ISGWO. Meanwhile, the position update formula with improved sinusoidal can better balance the development and exploration of ISGWO. The ISGWO algorithm is compared with three improved Gray Wolf algorithms on the CEC2017 test set as well as the synchronization controller. The experimental results show that the ISGWO algorithm has better selectivity, speed and robustness. [ABSTRACT FROM AUTHOR]

Using NaN3 and a chiral N-donor ligand (1R,2R)-1,2-diphenylethylenediamine (L) to react with Co(ClO4)2(H2O)6 and Ni(ClO4)2(H2O)6, respectively, two chiral CoIII and NiII complexes with formulae [Co(L)2(N3)2](ClO4)(0.5H2O) (1) and [Ni(L)2(μ1,3-N3)]n(ClO4)n(0.5H2O)n (2) were isolated and structurally characterized. Although 1 and 2 contain the same L and N3− ligands, they have completely different molecular structures. 1 shows a chiral mononuclear structure with N3− as the terminal ligand, in which the CoII ion has been oxidized to the CoIII ion, while 2 exhibits a chiral one-dimensional (1D) NiII chain structure with N3− as the bridging ligand. Notably, a study of their nonlinear optical (NLO) properties demonstrates that 1 presents a moderate second-harmonic generation (SHG) response (0.15 × KDP), while 2 only displays a strong third-harmonic generation (THG) response (160 × α-SiO2). This interesting finding gives the first example of the complexes with the same ligands but different molecular structures showing completely different NLO responses regulated by metal ions. [ABSTRACT FROM AUTHOR]

Employing a chiral N∧N-donor ligand (−)-4,5-pinene-2,2′-bipyridine (L) to react with Pr(dbm)3(H2O) and Ho(dbm)3(H2O), respectively, two chiral mononuclear lanthanide (LnIII) complexes with the formula [Ln(dbm)3(L)] [Ln = Pr (1) and Ho (2)] were obtained, in which dbm− = dibenzoylmethanate. Investigation on their photoluminescence properties reveals that 1 and 2 display characteristic near-infrared (NIR) emissions of PrIII and HoIII ions upon excitation with visible light (410 nm), respectively. More notably, study on their nonlinear optical (NLO) responses unveils that 1 and 2 not only present second-harmonic generation (SHG) responses due to their noncentrosymmetric molecular structures, but also exhibit strong third-harmonic generation (THG) responses simultaneously. THG intensities of 1 and 2 are 46.7 and 66.5 × α-SiO2, respectively, which are outstanding among the reported THG-active mononuclear LnIII complexes. 1 and 2 represent the first examples of LnIII complexes not only showing NIR luminescence but also displaying simultaneous SHG and THG responses. [ABSTRACT FROM AUTHOR]

The nitro groups are introduced into 4-(1H-1,2,4-triazol-1-yl) pyrimidine to substitute the hydrogen atoms successively, through which a total of 31 derivatives are constructed to look for high energy density compounds (HEDCs). To probe the thermal stabilities, the heats of formation (HOFs) are calculated by using the G3MP2 method. To explore the dynamic stability, the natural bond orbital (NBO) analysis is performed to confirm the trigger bond, for which the bond dissociation energy is calculated using the B3PW91 method with the 6-311 + G(d,p) basis set. Furthermore, the detonation velocity (D), the detonation pressure (P), the molecular density (ρ), the explosive heat (Q), and character height (H50) are also predicted. Based on our calculation, it is confirmed that D1, D2, D5, and E are potential high-energy-density compounds with sufficient stability and excellent detonation performance. [ABSTRACT FROM AUTHOR]

Amides or nitriles are important building blocks because of the widespread occurrence in chemistry and biology. The development of green and efficient catalytic approaches to introduce nitrogen functionality is highly desired. Herein, a vanadium‐based material V‐N‐C‐700 was prepared via a simple and convenient method and employed for liquid‐phase catalytic ammoxidation of alcohols with molecular oxygen. By using V‐N‐C‐700/2‐picolinic acid, primary aromatic alcohols was smoothly converted into the amides and nitriles in the presence of urea. The corresponding aldehydes are the key intermediates, and 2‐picolinic acid could significantly enhance oxidation of alcohols into aldehydes. The amides were formed simultaneously along with nitriles, rather than only from nitriles via successive hydration. This work further expands non‐noble metal catalysts for the preparation of amides and nitriles. [ABSTRACT FROM AUTHOR]