A novel feed rate scheduling method with acc-jerk-continuity and round-off error elimination for non-uniform rational B-spline interpolation

Hu Yifei,Jiang Xin,Huo Guanying,Su Cheng,Zhou Shiwei,Wang Bolun,Li Hexiong,Zheng Zhiming 한국CDE학회 2023 Journal of computational design and engineering Vol.10 No.1

Feed rate scheduling is a critical step in computer numerical control machining, as it has a close relationship with machining time and surface quality. It has now become a hot issue in both industry and academia. In this article, we present a novel and complete S-shape-based feed rate scheduling method for three-axis non-uniform rational B-spline (NURBS) tool paths, which can reduce high chord errors and round-off errors, and generate continuous velocity, acceleration, and jerk profile. The proposed feed rate scheduling method consists of three modules: a bidirectional scanning module, a velocity scheduling module, and a round-off error elimination module. The bidirectional scanning module aims to guarantee the continuity of the feed rate at the junctions between successive NURBS blocks, where the chord error, tangential acceleration, and tangential jerk limitations are considered. After the NURBS blocks have been classified into two cases by the previous module, the velocity scheduling module first calculates the actual maximum feed rate. It then generates the feed rate profiles of all NURBS blocks according to the proposed velocity profile. Later, the round-off error elimination module is applied to adjust the actual maximum feed rate so that the total interpolation time becomes an integer multiple of the interpolation period, which leads to the elimination of round-off errors. Finally, benchmarks are conducted to verify the applicability of the proposed method. Compared with the traditional method, the proposed method can save the interpolation time by $4.67$ to $14.26\% $.

Promotional effect of Ce in NH3-SCO and NH3-SCR reactions over Cu-Ce/ SCR catalysts

Wenjie Liu,Yifei Long,Shinian Liu,Yongyan Zhou,XinTong,Yajie Yin,Xiaoyi Li,Kang Hu,Jiangjun Hu 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.107 No.-

Commercial V-W-Ti catalysts were modified with Cu and different contents of Ce to remove slip ammoniaand remaining nitrogen oxide from the end stage of SCR technology. The activities of NH3 oxidation byO2 (NH3-SCO) and NO reduction by NH3 (NH3-SCR) of these catalysts were examined from 150 to 400 ℃. The consequences indicated that the addition of Ce and Cu could considerably enhance NH3 oxidation andNO reduction capacity of the catalysts and Ce was conducive to reduce the detrimental effects of H2O andSO2. The characterization tests indicated that the surface active oxygen increased because of the interactionbetween V, Cu and Ce. Moreover, the loaded Ce and Cu contributed to enhance the surface acidityand redox property of SCR catalysts.

Indirect Adaptive Robust Control Design for Course Tracking of Ships Subject to Unknown Control Coefficient and Disturbances

Jinbo Wu,Chenghao Zeng,Yifei Hu 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.6

For course control of ships with unknown control coefficient and model parameters, an indirect adaptive robust controller, in which the parameter estimation law and the control law are designed separately, is proposed. This design method can achieve not only excellent course control performance but also accurate parameter estimates for secondary purposes such as assisting in ship maneuvering decision. Firstly, a Nussbaum function is combined with the adaptive dynamic surface control method to design a strong robust controller which can ensure the stabilityof the closed-loop ship course control system in spite of parameter uncertainties, unknown control coefficient and disturbances. Secondly, the nonlinear model for ship steering is converted into linear form by using the X-swapping technique. And a modified least-squares identification algorithm is then proposed to estimate the unknown model parameters. The global uniform ultimate boundedness of all signals of the resulting closed-loop system is guaranteed via Lyapunov stability theory. Lastly, simulation results are executed to demonstrate the effectiveness of theproposed design method.

Comparative transcriptome analysis of salt-sensitive and salt-tolerant maize reveals potential mechanisms to enhance salt resistance

Mingquan Wang,Yufeng Wang,Yifei Zhang,Chunxia Li,Shichen Gong,Shuqin Yan,Guoliang Li,Guanghui Hu,Honglei Ren,Jianfei Yang,Tao Yu,Kejun Yang 한국유전학회 2019 Genes & Genomics Vol.41 No.7

Background Salt stress is a devastating environmental stress that causes plant growth inhibition and yield reduction. Objective The identification of salt-tolerant genes brings hope for the generation of salinity-tolerant crop plants through molecular breeding. Methods In this study, one salt-sensitive and one salt-tolerant maize inbred line were screened from 242 maize inbred lines. Reactive oxygen species (ROS)-related enzyme activities were detected and salt-responsive comparative transcriptome analysis was performed for control and 220 mM NaCl treated maize leaves. Results Salt-tolerant maize inbred line (L87) showed higher ROS-related enzyme (SOD, POD, APX and CAT) activities and accumulated relatively lower levels of ROS under salt stress. Of the total DEGs, 1856 upregulated DEGs were specific to L87, including stress tolerance-related members of the 70kDa family of heat shock proteins (Hsp70s) and aquaporins. The DEGs involved in the abscisic acid (ABA), ethylene, jasmonic acid (JA) and salicylic acid (SA) signal transduction pathways may determine the difference in salt tolerance between the two varieties, especially one central component SnRK2, that positively regulates ABA signaling and was only upregulated in L87. Analysis of DEGs related to ROS scavenging showed that some peroxidase (POD), glutathione S-transferase (GST), catalase (CAT) and superoxide dismutase (SOD) genes specific to L87 probably enhanced its salt tolerance. The analysis of differentially expressed transcription factors (TFs) suggested that WRKY TFs could contribute to the difference in salt tolerance between the two maize lines. Conclusion Compared with Salt-sensitive maize inbred line (L29), L87 exhibits specific regulatory mechanisms related to salt tolerance, including plant hormone interactions, ROS scavenging and the regulation of TFs. Our study identifies new candidate genes that may regulate maize tolerance to salt stress and provides useful information for breeding maize with high salt resistance.

Comparative transcriptome analysis of three chrysanthemums provides insights into flavonoid and terpenoid biosynthesis

Wang Xu,Zhang Jingjing,Liu Zhige,Wang Shuaibin,Huang Bisheng,Hu Zhigang,Liu Yifei 한국식물학회 2021 Journal of Plant Biology Vol.64 No.5

Chrysanthemum indicum var. aromaticum is an important resource plant for breeding excellent aromatic varieties of ornamental and medicinal chrysanthemums. However, the biosynthesis and regulation mechanisms of typically aromatic ingredients in C. indicum var. aromaticum are poorly understood, which restricted the utilization of this plant. Here, the transcriptome of C. indicum var. aromaticum was investigated and comparative analysis was conducted with the other two closely related chrysanthemum taxa C. indicum and C. nankingense. The global transcriptome profiles showed clear difference of gene expression patterns between the three chrysanthemums, of which 52 flavonoid biosynthesis-associated genes, 157 transcription factors, and 24 flavonoid Uridine diphosphate (UDP) -glucuronosyl and -glucosyltransferase genes were significantly differentially expressed. Furthermore, 22 differential expression genes (DEGs) in relation to the terpenoid backbone biosynthesis and 183 DEGs related to terpenoid diversification were identified. Of which, 14 genes involved into TS/CYP gene cluster showed higher expression in CIA than those in CI or CN. These results increased our understanding of flavonoid diversification and aromatic ingredients accumulation in plants, and will also help improve resource conservation and sustainable utilization of the important resource plant C. indicum var. aromaticum.