Model and Frequency Control for Three-Phase Wireless Power Transfer System

In order to the eliminate the “dead spot” in the traditional three-phase wireless power transfer (WPT) system, a three-phase WPT system with an asymmetric magnetic circuit is presented in this paper. Additionally, mathematical model of the system is established and the system parameters are optimized. Based on the fact that the resonant frequency and efficiency are greatly varied with the load, a method based on impedance conversion is further proposed to improve the frequency stability and system efficiency. Finally, simulation and experimental results show that the proposed method is reliable and feasible to eliminate the “dead spot.

Synthesis and Biological Activity of Trolox Amide Derivatives

A series of Trolox amide derivatives were synthesized by modifying the carboxyl groups of Trolox. Thirty target compounds were obtained and characterized through nuclear magnetic resonance and mass spectrometry. Trolox derivatives were employed to explore the potential structure-antioxidant activity relationships. The antioxidant activities of these compounds were evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP) and hydroxyl radical assays. DPPH scavenging activity test results illustrated that compounds exhibited scavenging activities similar to L-ascorbic acid and Trolox, with compounds 14a, 18a, 24a and 26a in particular exhibiting higher scavenging activities than L-ascorbic acid. The results demonstrated that compounds displayed ABTS scavenging activities similar to L-ascorbic acid and Trolox, with compounds 26a and 29a in particular having potency twofold higher. FRAP assay results indicated that compounds 11a, 19a, 25a, 29a and 30a had activity similar to Trolox. The results revealed that compounds 6a and 19a had similarly high hydroxyl radical-scavenging activities as Trolox. The results of α-glucosidase experiments uncovered that compounds 10a, 25a, 28a and 29a had excellent inhibitory activity, which was similar to that of acarbose and different from Trolox. The results of acetylcholinesterase and butyrylcholinesterase experiments demonstrated that some compounds had weak anticholinesterase activities. 26a and 29a are important Trolox derivatives with better biological activity profiles and deserve further study

Transcriptome analysis provides insights into the cell wall and aluminum toxicity related to rusty root syndrome of Panax ginseng

Rusty root syndrome is a common and serious disease in the process of Panax ginseng cultivation. This disease greatly decreases the production and quality of P. ginseng and causes a severe threat to the healthy development of the ginseng industry. However, its pathogenic mechanism remains unclear. In this study, Illumina high-throughput sequencing (RNA-seq) technology was used for comparative transcriptome analysis of healthy and rusty root-affected ginseng. The roots of rusty ginseng showed 672 upregulated genes and 526 downregulated genes compared with the healthy ginseng roots. There were significant differences in the expression of genes involved in the biosynthesis of secondary metabolites, plant hormone signal transduction, and plant–pathogen interaction. Further analysis showed that the cell wall synthesis and modification of ginseng has a strong response to rusty root syndrome. Furthermore, the rusty ginseng increased aluminum tolerance by inhibiting Al entering cells through external chelating Al and cell wall-binding Al. The present study establishes a molecular model of the ginseng response to rusty roots. Our findings provide new insights into the occurrence of rusty root syndrome, which will reveal the underlying molecular mechanisms of ginseng response to this disease

Trilinear Immersed-Finite-Element Method For Three-Dimensional Anisotropic Interface Problems In Plasma Thrusters

Accurately solving the anisotropic interface problem is one of the difficulties in aerospace plasma applications. Based on cubic Cartesian meshes, this paper develops a trilinear nonhomogeneous immersed finite element (IFE) method for solving the complex anisotropic 3D elliptic interface model with nonhomogeneous flux jump. Compared with the existing 3D linear IFE spaces based on tetrahedron meshes, the newly designed trilinear IFE space for the target model simplifies the mesh generation, significantly reduces the number of mesh elements and interface elements, provides much more convenient and efficient ways for finding the intersections between interfaces and mesh edges, and decreases the errors. These advantages lead to much higher efficiency when solving complex anisotropic interface problems in practice. In addition, the proposed method can be easily incorporated into other typical methods based on Cartesian meshes, such as the particle-in-cell method for plasma simulation. Numerical experiments are provided to verify the optimal accuracy, high efficiency, and reliability of the proposed method for solving complex interface problems, as well as its applicability to practical plasma thruster problems

Fast Segmentation of Vertebrae CT Image Based on the SNIC Algorithm

Automatic image segmentation plays an important role in the fields of medical image processing so that these fields constantly put forward higher requirements for the accuracy and speed of segmentation. In order to improve the speed and performance of the segmentation algorithm of medical images, we propose a medical image segmentation algorithm based on simple non-iterative clustering (SNIC). Firstly, obtain the feature map of the image by extracting the texture information of it with feature extraction algorithm; Secondly, reduce the image to a quarter of the original image size by downscaling; Then, the SNIC super-pixel algorithm with texture information and adaptive parameters which used to segment the downscaling image to obtain the superpixel mark map; Finally, restore the superpixel labeled image to the original size through the idea of the nearest neighbor algorithm. Experimental results show that the algorithm uses an improved superpixel segmentation method on downscaling images, which can increase the segmentation speed when segmenting medical images, while ensuring excellent segmentation accuracy

Consensus Cooperative Encirclement Interception Guidance Law for Multiple Vehicles against Maneuvering Target

This paper studies a cooperative encirclement interception guidance law against a maneuvering target that utilizes a leader–follower control scheme. The control design is decoupled into two parts. In the line-of-sight (LOS) direction, a fixed-time distributed disturbance observer is presented to estimate the maneuvering of the target. Based on the proposed disturbance observer, the guidance law is designed for the followers to guarantee that each follower’s total flight time achieves consensus with that of the leader. In the normal direction of the LOS, the control command is designed to realize the encirclement interception with a predefined-time consensus protocol. The convergence of the guidance algorithm is proven by the Lyapunov stability theory. Numerical simulations are provided to demonstrate the effectiveness and superiority of the proposed cooperative-guidance law