Active Fault Tolerant Control of an Unmanned Surface Vehicle

Zhixiang Liu,Youmin Zhang,Chi Yuan 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10

This paper presents an active fault tolerant control methodology with application to an unmanned surface vehicle (USV). Firstly, an augmented linear quadratic regulator (LQR) scheme is developed to guarantee the desired control performance and stability of USV in the absence of actuator faults. Secondly, an additional control mechanism incorporating a fault estimator and an adaptive fault compensator are synthesized to asymptotically stabilize the closedloop system in the event of actuator faults. Based on a nonlinear USV model, simulation results validated the effectiveness of the proposed control approach in either the absence or presence of actuator faults.

Biomimetic Total Synthesis of Paeoveitol

Zhang, Yuhan,Guo, Yonghong,Li, Zhongle,Xie, Zhixiang American Chemical Society 2016 ORGANIC LETTERS Vol.18 No.18

<P>A highly stereocontrolled synthesis of paeoveitol has been developed in 26% yield, in 7 steps from commercially available materials. The synthetic strategy was inspired primarily by the biogenetic hypothesis and was enabled by hetero-Diels–Alder cycloaddition to construct the target molecular framework.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/orlef7/2016/orlef7.2016.18.issue-18/acs.orglett.6b02228/production/images/medium/ol-2016-02228p_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ol6b02228'>ACS Electronic Supporting Info</A></P>

An Analysis of the Uneven Tool Electrode Wear Mechanism in the Micro-electrical Discharge Machining Process

Zhixiang Zou,Xiaoyu Zhang,Kangcheung Chan,Tai-Man Yue,Zhongning Guo,Can Weng,Jiangwen Liu 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.6

Micro-electrical discharge machining (micro-EDM) has an issue of uneven tool electrode wear that seriously affects the micro-hole accuracy. However, the mechanism of uneven tool electrode wear remains unclear. In this study, the uneven tool electrode wear mechanism has been studied both theoretically and experimentally. It was first discovered that the ultrafine debris particles produced by the EDM spark play a critical role in uneven tool electrode wear. A theoretical model was established to reveal the movement and the distribution of the debris by employing Einstein’s tea leaf paradox i.e., classic secondary flow theory and the electrophoretic theory. According to this model, when the polarity is positive, the ultrafine debris aggregates gradually and adheres onto the bottom of the micro-hole, thereby a debris layer of a parabolic profile is formed progressively. This dynamic debris layer shields the material to be removed by the EDM spark. As a result, the tip of the tool electrode is unevenly worn into a conical concavity shape. Conversely, under negative polarity, the tip of the tool electrode is unevenly worn into a conical shape. A set of experiments was performed to verify the model and the results agreed well with the predicted phenomena. Subsequently, a novel approach is proposed to eliminate the uneven tool electrode wear by reversing pulse polarity in a repetitive manner. Using this method, uneven tool electrode wear can be avoided and high accuracy micro-holes without the features of a cone and/or conical concavity can be obtained.

Graded-Three-Dimensional Cell-Encapsulating Hydrogel as a Potential Biologic Scaffold for Disc Tissue Engineering

Li Zhixiang,Zhang Yiwen,Zhao Yupeng,Gao Xubin,Zhu Zhonglian,Mao Yingji,Qian Taibao 한국조직공학과 재생의학회 2022 조직공학과 재생의학 Vol.19 No.5

BACKGROUND: Intervertebral disk (IVD) degeneration, which can cause lower back pain, is a major predisposing factor for disability and can be managed through multiple approaches. However, there is no satisfactory strategy currently available to reconstruct and recover the natural properties of IVDs after degeneration. As tissue engineering develops, scaffolds with embedded cell cultures have proved critical for the successful regeneration of IVDs. METHODS: In this study, an integrated scaffold for IVD replacement was developed. Through scanning electron microscopy and other mechanical measurements, we characterized the physical properties of different hydrogels. In addition, we simulated the physiological structure of natural IVDs. Nucleus pulposus (NP) cells and annulus fibrosusderived stem cells (AFSCs) were seeded in gelatin methacrylate (GelMA) hydrogel at different concentrations to evaluate cell viability and matrix expression. RESULTS: It was found that different concentrations of GelMA hydrogel can provide a suitable environment for cell survival. However, hydrogels with different mechanical properties influence cell adhesion and extracellular matrix component type I collagen, type II collagen, and aggrecan expression. CONCLUSION: This tissue-engineered IVD implant had a similar structure and function as the native IVD, with the inner area mimicking the NP tissue and the outer area mimicking the stratified annulus fibrosus tissue. The new integrated scaffold demonstrated a good simulation of disc structure. The preparation of efficient and regeneration-promoting tissueengineered scaffolds is an important issue that needs to be explored in the future. It is hoped that this work will provide new ideas and methods for the further construction of functional tissue replacement discs.

COMPONENT RESISTANCE PREDICTION IN COMPOUND CHANNELS

LIU XINGNIAN,ZHANG ZHIXIANG,YANG KEJUN,CAO SHUYOU 한국수자원학회 2005 한국수자원학회 학술대회 Vol.2005 No.1

High-performance broadband heterojunction photodetectors based on multilayered PtSe₂ directly grown on a Si substrate

Xie, Chao,Zeng, Longhui,Zhang, Zhixiang,Tsang, Yuen-Hong,Luo, Linbao,Lee, Jung-Ho The Royal Society of Chemistry 2018 Nanoscale Vol.10 No.32

<P>Two-dimensional group-10 transition metal dichalcogenides have recently attracted increasing research interest because of their unique electronic and optoelectronic properties. Herein, we present vertical hybrid heterojunctions of multilayered PtSe2 and Si, which take advantage of large-scale homogeneous PtSe2 films grown directly on Si substrates. These heterojunctions show obvious rectifying behavior and a pronounced photovoltaic effect, enabling them to function as self-driven photodetectors operating at zero bias. The photodetectors can operate in both photovoltage and photocurrent modes, with responsivity values as high as 5.26 × 10<SUP>6</SUP> V W<SUP>−1</SUP> and 520 mA W<SUP>−1</SUP> at 808 nm, respectively. The <I>I</I>light/<I>I</I>dark ratio, specific detectivity, and response speed are 1.5 × 10<SUP>5</SUP>, 3.26 × 10<SUP>13</SUP> Jones, and 55.3/170.5 μs, respectively. Furthermore, the heterojunctions are highly sensitive in a broad spectral region ranging from deep ultraviolet to near-infrared (NIR) (200-1550 nm). Because of the strong NIR light absorption of PtSe2, the heterojunctions exhibit photocurrent responsivities of 33.25 and 0.57 mA W<SUP>−1</SUP> at telecommunication wavelengths of 1310 and 1550 nm, respectively. Considering the excellent performance of the PtSe2/Si heterojunctions, they are highly suitable for application in high-performance broadband photodetectors. The generality of the above results also signifies that the proposed <I>in situ</I> synthesis method has great potential for future large-scale optoelectronic device integration.</P>

Microwave Absorption Enhancement of Fe/C Core–Shell Hybrid Derived from a Metal-Organic Framework

Liuyang Heng,Zilong Zhang,Shuai Wang,Xiqiao Chen,Xiubo Jia,Zhixiang Tang,Yanhong Zou 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.1

Core–shell structured Fe/C have been successfully derived from a metal-organic framework for microwave absorbing. Based on the measured electromagnetic parameters, it is found that the maximum reflection loss (RL) of Fe/C reaches 40 dB at 5.8 GHz with a thickness of 3.0 mm and the broadest absorption bandwidth (RL < -10 dB) is up to 6.0 GHz (from 11.2 to 17.2 GHz) with a thickness of 1.5 mm. The excellent microwave absorption is mainly ascribed to the multiple reflections, good impedance matching, dielectric loss and interface polarization originating from the core–shell structure. It is believed that Fe/C can be a promising microwave absorbing material.

STAGE-DISCHARGE CURVE AND ITS PREDICTION IN COMPOUND CHANNELS

CAO SHUYOU,YANG KEJUN,ZHANG ZHIXIANG,LIU XINGNIAN 한국수자원학회 2005 한국수자원학회 학술대회 Vol.2005 No.1

Chlorogenic acid accumulation and related gene expression in peach fruit

Yan Juan,Su Ziwen,Guo Shaolei,Zhang Minghao,Zhang Binbin,Cai Zhixiang,Shen Zhijun,Ma Ruijuan,Yu Mingliang 한국원예학회 2022 Horticulture, Environment, and Biotechnology Vol.63 No.3

To reveal the molecular mechanism in the accumulation of chlorogenic acids (CGAs) in peach (Prunus persica) fruit during growth and development, CGA contents in the flesh of the three peach cultivars ‘Ruiguang 18’, ‘Heiyoutao’, and ‘Beijingyixianhong’ were determined. The expression levels of CGA metabolism-related genes were analyzed based on transcriptome data (RNA-seq). These candidate genes were then screened and real-time fluorescent quantitative PCR (qRT-PCR) was performed to verify their expression. The results showed that the content of total CGAs, 5-O-caffeoylquinic acid and 3-O-caffeoylquinic acid, in the flesh of ‘Ruiguang 18’ exhibited a decreasing trend during fruit development, and there was a great drop at maturity stage (P < 0.05). The three contents in ‘Heiyoutao’ increased first at stage S2 (P < 0.05) and then decreased significantly (P < 0.05). In ‘Beijingyixianhong’, they stayed stable in the early stages, then total CGAs and 3-O-caffeoylquinic acid decreased significantly at the maturity stage (P < 0.05). RNA-seq transcriptome data analysis and qRT-PCR expression analysis showed that the accumulation of CGAs in fruit flesh was mainly affected by the expression of Prupe.3G100800 (PpHCT) and Prupe.3G107300 (Pp4CL), and their expression levels were highly consistent with total CGA content. Thus, we concluded that Prupe.3G100800 (PpHCT) and Prupe.3G107300 (Pp4CL) are the key genes for CGAs synthesis in peach flesh.

Application of the sheet electrode to enhance the geometric characteristics of micro-holes fabricated by electrochemical discharge machining

Zhongning Guo,Shunzhi Qiao,Liangliang Wang,Kai Zhang,Yingjie Xiao,Zhixiang Zou 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.11

The electrochemical discharge machining (ECDM) is an advanced machining technology used to fabricate micro-holes in glass. In this study, a sheet tool electrode is employed to increase electrolyte circulation in machining zone. The effect of pulse voltage, frequency, duty cycle, electrolyte concentration, and tool rotation speed on the geometric properties of micro-holes were evaluated. The results showed that when using a sheet tool electrode, the machining depth increased by 42.9 %, and the machining efficiency increased by 51.1 %, while the entrance diameter was reduced by 13.9 % than cylindrical tool electrode. Additionally, the heat-affected zone (HAZ) and entrance hole surface quality is improved. On the other hand, the Taguchi method was employed to analyze the relative importance of the machining parameters on geometric characteristics of micro-holes (i.e. drilled depth and entrance diameter of micro-holes). Finally, the entrance hole overcut of 148 μm was successfully fabricated with a depth of 2520 μm. It was discovered that using a sheet tool electrode is a simple method for machining a deep micro-hole with high machining efficiency and a range entrance hole diameter overcut that is acceptable.