Dynamic optimization of robot arm based on flexible multi-body model

Mingxuan Liang,Binrui Wang,Tianhong Yan 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.8

This paper examines the effect mechanism of torsional stiffness on flexible joints and the dynamic optimization of a six Degree-offreedom industrial robot arm. The design optimization of the robot arm is investigated based on the rotor-torsional spring model and finite element method. The flexible multi-body dynamic model of the robot arm are established by considering the flexible characteristics of arms and joints, and the natural frequencies of a robot arm are calculated to obtain the torsional stiffness of the flexible joints. Natural frequency results gradually increased with joint stiffness improvement. Using the established dynamic model, the topology optimization on the robot arm is carried out by regarding lightweight as design goal and total displacement as constraints. The tare-load ratio and dynamic performance of the optimized robot arm are significantly enhanced compared with the original design model. This research can provide the theoretical basis for the dynamic optimization and upgrade of lightweight robot arm.

Asymptotic behavior of solutions for the generalized MHD and Hall-MHD systems in $\mathbb{R}^n$

Mingxuan Zhu 대한수학회 2018 대한수학회보 Vol.55 No.3

This paper deals with the asymptotic behavior of solutions to the generalized MHD and Hall-MHD systems. Firstly, the upper bound for the generalized MHD and Hall-MHD systems is investigated in $L^2$ space. Then, the effect of the Hall term is analyzed. Finally, we optimize the upper bound of decay and obtain their algebraic lower bound for the generalized MHD system by using Fourier splitting method.

GaAsBi Quantum Dots for 1.55 μm Laser Diode

Mingxuan Zhang,Liyao Zhang,Zhongyue Zhang,Peng Yu,Shuang Yao 대한금속·재료학회 2021 ELECTRONIC MATERIALS LETTERS Vol.17 No.2

Bi incorporations can reduce the bandgap of GaAs1-xBix. With a Bi content of 10.5%, GaAsBi is predicted to emit light at1.55 μm. However, high Bi incorporation is difficult for material growth and deteriorates the optical property of GaAsBi. In this work, a GaAsBi quantum dot (QD)/InAlAs structure on InP platform is proposed to fabricate 1.55 μm laser diodes. Strain distributions and band structures are calculated with different Bi contents and QD sizes using finite element method. High Bi contents and large QD sizes are beneficial for achieving long wavelengths. GaAsBi QD/InAlAs structures with alow Bi content of 5.6% and proper QD sizes, such as a diameter of 30 nm and a height of 6 nm, can emit light at 1.55 μm. The proposed structure can be realized by migration enhanced epitaxy and droplet epitaxy and provides a feasible way forfabricating GaAsBi based 1.55 μm laser diodes applied in fiber-optic communications.

ASYMPTOTIC BEHAVIOR OF SOLUTIONS FOR THE GENERALIZED MHD AND HALL-MHD SYSTEMS IN ℝⁿ

Zhu, Mingxuan Korean Mathematical Society 2018 대한수학회보 Vol.55 No.3

This paper deals with the asymptotic behavior of solutions to the generalized MHD and Hall-MHD systems. Firstly, the upper bound for the generalized MHD and Hall-MHD systems is investigated in $L^2$ space. Then, the effect of the Hall term is analyzed. Finally, we optimize the upper bound of decay and obtain their algebraic lower bound for the generalized MHD system by using Fourier splitting method.

DsbM, a Novel Disulfide Oxidoreductase Affects Aminoglycoside Resistance in Pseudomonas aeruginosa by OxyR-Regulated Response

Xuehan Wang,Mingxuan Li,Liwei Liu,Rui Mou,Xiuming Zhang,Yanling Bai,Haijin Xu,Mingqiang Qiao 한국미생물학회 2012 The journal of microbiology Vol.50 No.6

A Pseudomonas aeruginosa mutant strain M122 was isolated from a Mu transposon insertion mutant library. In our prophase research, we have found that PA0058, a novel gene encodes a 234-residue conserved protein, was disrupted in the M122 mutant. In this study, the bacteriostatic experiment in vitro indicates that M122 has abnormally high aminoglycoside resistance. We expressed PA0058 in E. coli and found that PA0058 oxidizes and reduces disulfide. This biochemical characterization suggests that PA0058 is a novel disulfide oxidoreductase. Hence, the protein was designated as DsbM. Microarray analysis of the M122 mutant showed its unusual phenotype might be related to the bacterial antioxidant defense system mediated by the oxyR regulon. Meanwhile, we detected –SH content in the periplasm of M122 and wild strain and found a lower –SH/S–S ratio in M122. Therefore, we consider that the loss of dsbM function decreased the –SH/S–S ratio, which then prolongs the OxyR-regulated response, thereby conferring high aminoglycoside resistance to the M122 mutant strain. Our findings have important implications for understanding the mechanisms underlying aminoglycoside resistance in P. aeruginosa.

LMI-Based Synthesis of Robust Iterative Learning Controller with Current Feedback for Linear Uncertain Systems

Jianming Xu,Mingxuan Sun,Li Yu 대한전기학회 2008 International Journal of Control, Automation, and Vol.6 No.2

This paper addresses the synthesis of an iterative learning controller for a class of linear systems with norm-bounded parameter uncertainties. We take into account an iterative learning algorithm with current cycle feedback in order to achieve both robust convergence and robust stability. The synthesis problem of the developed iterative learning control (ILC) system is reformulated as the γ-suboptimal H∞ control problem via the linear fractional transformation (LFT). A sufficient convergence condition of the ILC system is presented in terms of linear matrix inequalities (LMIs). Furthermore, the ILC system with fast convergence rate is constructed using a convex optimization technique with LMI constraints. The simulation results demonstrate the effectiveness of the proposed method.

Distribution of diagenetic alterations within depositional facies and sequence stratigraphic framework of fan delta and subaqueous fan sandstones: evidence from the Lower Cretaceous Bayingebi Formation, Chagan sag, China–Mongolia frontier area

Wei Wei,Xiaomin Zhu,Mingxuan Tan,Chenbingjie Wu,Dianbin Guo,Hui Su 한국지질과학협의회 2016 Geosciences Journal Vol.20 No.1

Linking siliciclastic diagenesis to sequence stratigraphy allows a better understanding of the parameters controlling the spatial and temporal distribution of diagenetic alterations. A study of the subaqueous fan and fan delta sandstones of the Bayingebi Formation, Lower Cretaceous, Chagan sag (China), reveals that the distribution of diagenetic alterations can be constrained within a sequence stratigraphic framework. Eogenetic alterations, which were encountered in the sandstones of subaqueous fan and fan delta, include: (1) replacement of detrital silicates and mud matrix by kaolinites in sandstones of the late highstand systems tract (HST) and the lowstand systems tract (LST). The formation of kaolinites is attributed to the influx of meteoric water when the base level fell and the channels migrated laterally on preexisting floodplains or channel deposits. (2) Infiltrated clays, which rim around detrital grains, mainly occur in channel sandstones of the LST due to the percolation of mud-rich surface waters. (3) Calcite I (δ18OVPDB = –20.19‰ to −3.64‰ and δ13CVPDB = –0.67‰ to –3.1‰), Calcite II (δ18OVPDB = –14‰ to –18.28‰ and δ13CVPDB = –2.2‰ to –3.60‰), dolomite (δ18OVPDB = –17.91‰ to –21.04‰ and δ13CVPDB = –0.46‰ to –1.66‰) and ankerite (δ18OVPDB = –15.02 to –20.42‰ and δ13CVPDB = –0.074 to –1.43‰), which are associated with palaeosol horizons mainly developed on top of overbank and channel sandstones of transgressive systems tract (TST) and early stage of the HST. Such extensive eogenetic calcite cements may act as potential layers for the formation of reservoir compartments for underlying sandstones. Mesogenetic alterations include: (1) abundant quartz overgrowths in the overbank sandstones of subaqueous fan in the LST and pro-fan-delta sandstones in the HST, in which early carbonate cements are lacking and grain-coats are thin. (2) Illite, chlorite and albitized feldspars, which occur in small amounts, are most common in the LST and late stage of the HST sandstones. Such cementation by calcite, dolomite, quartz overgrowths and formation of illite led to porosity and permeability deterioration during mesodiagenesis. This study revealed the importance of integration of diagenesis with sequence stratigraphy of subaqueous fan and fan delta sandstones in improving our ability to predict the spatial and temporal distribution of eogenetic alterations and their subsequent impact on mesogenetic alterations, and thus on reservoir quality modifications.

Normative Visual Patterns for Hazard Recognition: A Crisp-Set Qualitative Comparative Analysis Approach

Heap-Yih Chong,Mingxuan Liang,Pin-Chao Liao 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.5

Understanding the mental representations used for hazard recognition would help the development of inspection strategies for effective safety management. This study is part of ongoing research to identify hazard recognition patterns based on users’ mental representations. Hence, this study explored normative visual patterns for improving hazard recognition performance using a crisp-set qualitative comparative analysis (cs-QCA). Eye-tracking data and visual trajectories were collected using an eye-tracking device in a structural laboratory. A cs-QCA approach was adopted to analyze and summarize normative visual patterns that were used to successfully detect hazards by all participants, namely, potential electrical contact, a large machine with no guardrails, and steel bars dump. The results show that object identification should suffice as the basis for identifying electricity-related hazards, while struck-by hazards should focus on the objects and their pivot points or potential movement trajectories. The experimental design and analytical approach provide new insights into visual analytics in hazard recognition. The research extends and supplements recognition by component theory in the context of construction hazard recognition. The results also provide new and practical references for hazard inspection training, as well as for future development of automated hazard recognition systems.

Hydrogen Peroxide produced by Two Amino Acid Oxidases Mediates Antibacterial Actions

Hongmin Zhang,Qiuyue Yang,Mingxuan Sun,Maikun Teng,Liwen Niu 한국미생물학회 2004 The journal of microbiology Vol.42 No.4

The antibacterial actions of two amino acid oxidases, a D-amino acid oxidase from hog kidney and a L-amino acid oxidase from the venom of Agkistrodon halys, were investigated, demonstrating that both enzymes were able to inhibit the growth of both Gram-positive and Gram-negative bacteria, and that hydrogen peroxide, a product of their enzymatic reactions, was the antibacterial factor. However, hydrogen peroxide generated in the enzymatic reactions was not sufficient to explain the degree to which bacterial growth was inhibited. A fluorescence labeling assay showed that both of these two enzymes could bind to the surfaces of bacteria. To the best of our knowledge, this is the first report regarding the antibacterial activity of the D-amino acid oxidases.

Harmonic resonance analysis and stability improvement for grid-connected inverters

Xie, Bao,Zhou, Lin,Liu, Tiantian,Mao, Mingxuan The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.1

The traditional dual-control-loop strategy is widely used in grid-connected inverters. However, due to uncertain grid conditions, a resonance phenomenon may arise in systems and grid current can be badly distorted. In addition, the systems themselves may be unstable. In this paper, an equivalent impedance model of a grid-connected inverter is established. Based on this, two concepts of circuit resonance and harmonic resonance are proposed. By using the Nyquist stability criterion, it is revealed that harmonic resonance is induced when system stability is decreased, and the harmonic amplification in the system is enhanced. Due to the fact that the dual-control-loop strategy has poor robustness against grid impedance variations, a linear quadratic regulator (LQR) based on full-state feedback is proposed in this paper. The design procedure for selecting the full-state feedback gain is presented. Finally, both simulation and experimental results are presented to verify the effectiveness of the proposed LQR controller.