Trajectory Synthesis and Optimization of an Underactuated Microrobotic System with Dynamic Constraints and Couplings

Pengcheng Liu,Hongnian Yu,Shuang Cang 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.5

Motivated by the desire to optimally control the friction-induced stick-slip locomotion and sufficiently improve the energy efficacy, a novel trajectory synthesis and optimization scheme is proposed in this paper for a underactuated microrobotic system with dynamic constraints and couplings. The nonlinear microrobotic model utilizes combined tangential-wise and normal-wise vibrations for underactuated locomotion, which features a generic significance for the studies on microrobotic systems. Specifically, an analytical two-stage velocity trajectory is constructed under control indexes and physical constraints. Subsequently, the dynamic coupling behavior and the qualitative variation laws are characterized through rigorous bifurcation analysis. The synthesized trajectory is optimized and tuned via rigorous analysis based on the robot dynamics. The proposed trajectory planning mechanism provides a promising approach in determining the optimal viscoelastic parameters and trajectory parameters such that the optimal locomotion indexes can be met. Simulation results are presented to demonstrate the efficacy and feasibility of the proposed scheme.

Offshore Wind Converter Reliability Evaluation

Pengcheng Zhu,Yunfeng Liu,Roesner Robert,Xin Hao 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

Offshore wind turbine is facing the challenges of harsh environment and low accessibility etc. To make offshore wind business success for long-term operation, high reliability is very important to make the system get the same availability as its onshore counterparts. According to existing statistics, about 40% system faults are related to wind converters. Some of the faults are caused by improper design, and others come from worst-case operation and improper control. All these related to the converter reliability issue. To get full understanding of wind converter reliability issue, this paper introduces a systematic method that includes the converter failure model evaluation and analysis (FMEA), reliability modeling & calculation, availability calculation, reliability test design and worst-case shock simulation/evaluation. Based on these methods, a typical wind converter system is analyzed. According results and improvement instructions are presented..

Highly selective separation of vanadium over iron from stone coal by oxalic acid leaching

Pengcheng Hu,Yimin Zhang,Tao Liu,Jing Huang,Yizhong Yuan,Qiushi Zheng 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.45 No.-

In this paper, a novel method was proposed to selectively extract vanadium from stone coal by oxalicacid leaching. Vanadium was leached, but the iron impurity wasmaintained in the leaching residue. Theeffects of leaching conditions on the leaching efficiency of vanadium and iron were investigated foroxalic and sulfuric acid leaching, respectively. For oxalic acid leaching, 71.5% of the vanadium can berecovered with only 3.4% of the iron impurity leached under the leaching conditions: a dosage of H+ of12 mol/kg, a leaching time of 6 h, a leaching temperature of 368 K (95 8C) and a water–mineral ratio of1.5 L/kg. However, under the same conditions, 74.1% of the vanadium and 13% of the iron were leachedduring sulfuric acid leaching. The XRD and FTIR analyses showed that both oxalic and sulfuric acidleaching can destroy the crystal lattice structure of muscovite, resulting in the leaching efficiency ofvanadium without much difference. Further, the SEM-EDS and XPS analyses indicated that very littlepyrite dissolved during oxalic acid leaching, but that much more pyrite dissolved during sulfuric acidleaching. Therefore, oxalic acid leaching can achieve a highly selective separation of vanadium over ironfrom stone coal.

Hyper-branched sensing polymer directly constructed on a resonant micro-cantilever for the detection of trace chemical vapor

Liu, Yongjing,Xu, Pengcheng,Yu, Haitao,Zuo, Guomin,Cheng, Zhenxing,Lee, D.-W.,Li, Xinxin The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.34

<P>A hyper-branched polymer is layer-by-layer self-assembled on a resonant micro-cantilever and, then, functionalized with sensing-terminals for the specific detection of the trace chemical vapor of dimethyl methylphosphonate (DMMP, a typical simulant for nerve agents). The hyper-branched polymer is directly constructed on the SiO<SUB>2</SUB> surface of the cantilever <I>via</I> an A<SUB>2</SUB> + B<SUB>4</SUB> layer-by-layer route, where A<SUB>2</SUB> and B<SUB>4</SUB> are complementary interacting groups which undergo coupled linking. After modification with 4-(2-(4-(allyloxy)phenyl)-1,1,1,3,3,3-hexafluoropropan-2-yl)phenol (APHFPP) groups specific to DMMP, the high specific-surface-area hyper-branched polymer provides very dense sensing sites to adsorb a great number of DMMP molecules for micro-gravimetric detection. Moreover, the sensing polymer possesses a “more branches but fewer roots” configuration on the cantilever surface to depress the cross-talk effect caused by adsorption induced cantilever spring-stiffening. Experimental results indicate that, self-assembled with the hyper-branched sensing polymer, the resonant cantilevers exhibit rapid and reproducible detection of trace DMMP (with the detection limit lower than 7.2 ppb) and effectively depressed parasitic frequency-shift from the cantilever spring stiffening effect. In addition, the sensor features satisfactory selectivity in the presence of water and organic solvents. When an alternative sensing-group of 2-allylhexafluoroisopropanol (AHFIP) is modified on the hyper-branched architecture, the cantilever becomes specifically sensitive to trace explosive vapor. Therefore, the developed technique for the functionalization of hyper-branched polymer directly grown on a cantilever provides a widely usable micro/nano sensing-platform for the detection of trace chemical vapors.</P> <P>Graphic Abstract</P><P>A hyperbranched polymer is directly grafted onto a resonant micro-cantilever surface. The polymer is functionalized with sensing terminal groups and it exhibits the selective, rapid and reproducible detection to trace dimethyl methylphosphonate, with the detection limit lower than 7.2 ppb. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm33202g'> </P>

Analytical Modeling of Resonant Converters in Frequency Domain for Wireless Power Transfer

Younghui Liu,Hulong Zeng,Pengcheng Jiao 대한교통학회 2023 대한교통학회 학술대회지 Vol.89 No.-

Code development on steady-state thermal-hydraulic for small modular natural circulation lead-based fast reactor

Zhao, Pengcheng,Liu, Zijing,Yu, Tao,Xie, Jinsen,Chen, Zhenping,Shen, Chong Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.12

Small Modular Reactors (SMRs) are attracting wide attention due to their outstanding performance, extensive studies have been carried out for lead-based fast reactors (LFRs) that cooled with Lead or Lead-bismuth (LBE), and small modular natural circulation LFR is one of the promising candidates for SMRs and LFRs development. One of the challenges for the design small modular natural circulation LFR is to master the natural circulation thermal-hydraulic performance in the reactor primary circuit, while the natural circulation characteristics is a coupled thermal-hydraulic problem of the core thermal power, the primary loop layout and the operating state of secondary cooling system etc. Thus, accurate predicting the natural circulation LFRs thermal-hydraulic features are highly required for conducting reactor operating condition evaluate and Thermal hydraulic design optimization. In this study, a thermal-hydraulic analysis code is developed for small modular natural circulation LFRs, which is based on several mathematical models for natural circulation originally. A small modular natural circulation LBE cooled fast reactor named URANUS developed by Korea is chosen to assess the code's capability. Comparisons are performed to demonstrate the accuracy of the code by the calculation results of MARS, and the key thermal-hydraulic parameters agree fairly well with the MARS ones. As a typical application case, steady-state analyses were conducted to have an assessment of thermal-hydraulic behavior under nominal condition, and several parameters affecting natural circulation were evaluated. What's more, two characteristics parameters that used to analyze natural circulation LFRs natural circulation capacity were established. The analyses show that the core thermal power, thermal center difference and flow resistance is the main factors affecting the reactor natural circulation. Improving the core thermal power, increasing the thermal center difference and decreasing the flow resistance can significantly increase the reactor mass flow rate. Characteristics parameters can be used to quickly evaluate the natural circulation capacity of natural circulation LFR under normal operating conditions.

Toward Understanding the Adsorption And Inhibition Mechanism of Cu‑MBTA Passivation Film on Copper Surface: A Combined Experimental and DFT Investigation

Mengrui Liu,Da Yin,Baimei Tan,Fan Yang,Xiaoqin Sun,Pengcheng Gao,Shihao Zhang,Yazhen Wang 대한금속·재료학회 2021 ELECTRONIC MATERIALS LETTERS Vol.17 No.1

The adsorption and passivation reactions of 5-methyl benzotriazole (MBTA) with different copper samples (as received, citricacid treated and citric acid and KIO4treated) were studied. The experiments were characterized by contact angle measurement,potentiodynamic polarization curve, electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. The results showed that the adsorption behavior of MBTA on different treated surfaces was different and MBTA was preferentiallyadsorbed on the surface of citric acid treated copper. Based on the density functional theory, quantum chemicaldescriptors such as the frontier molecular orbital energies EHOMO,ELUMOand the energy gap between them, molecularelectrostatic potential, and Fukui function had been calculated and discussed. The adsorption mechanism of MBTA andcopper surface was further revealed, which had positive significance for the corrosion inhibition of copper surface in copperinterconnection CMP.

Analytical Modeling of Resonant Converters in Frequency Domain for Wireless Power Transfer

Yonghui Liu,Hulong Zeng,Pengcheng Jiao 대한교통학회 2023 대한교통학회 학술대회지 Vol.89 No.-

CFD ANALYSIS AND REDESIGN OF THE FRANCIS TURBINE WITH LARGE HEAD VARIATION

GUO PENGCHENG,LUO XINGQI,LIU SHENGZHU 한국수자원학회 2005 한국수자원학회 학술대회 Vol.2005 No.1

Self-assembly and sensing-group graft of pre-modified CNTs on resonant micro-cantilevers for specific detection of volatile organic compound vapors

Xu, Pengcheng,Li, Xinxin,Yu, Haitao,Liu, Min,Li, Jungang IOP 2010 JOURNAL OF MICROMECHANICS AND MICROENGINEERING - Vol.20 No.11

<P>This paper reports MWCNT (multi-wall carbon nano-tube)-modified resonant micro-cantilever chemical sensors for detection of trinitrotoluene (TNT) vapor. The MWCNTs are pre-modified and then area-selectively self-assembled at the free-end gold pad of a micro-cantilever, in which a resonance-exciting heater and a signal-readout piezoresistive Wheatstone bridge are integrated. Featuring a high specific surface area, the MWCNTs are further functionalized with TNT-sensitive groups by grafting onto the sidewalls of the MWCNTs. To lower the non-specific absorption of water and other small organic molecules, the SiO<SUB>2</SUB> surface of the micro-cantilever was also pre-treated for hydrophobicity and oleophobicity by self-assembling a monolayer of heptadecafluorodecyltrimethoxysilane. The results of our sensing experiments have shown a capability to rapidly detect ppb-level TNT vapor, and a high specificity of the functionalized groups to TNT molecules. The experiment has also confirmed a good long-term stability in detecting sensitivity.</P>