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| 1 | Bifurcation and Chaos Analysis of Nonlinear Rotor System with Axial-grooved Gas-lubricated Journal Bearing Support显示文摘Axial-grooved gas-lubricated journal bearings have been widely applied to precision instrument due to their high accuracy, low friction, low noise and high stability. The rotor system with axial-grooved gas-lubricated journal bearing support is a typical nonlinear dynamic system. The nonlinear analysis measures have to be adopted to analyze the behaviors of the axial-grooved gas-lubricated journal bearing-rotor nonlinear system as the linear analysis measures fail. The bifurcation and chaos of nonlinear rotor system with three axial-grooved gas-lubricated journal bearing support are investigated by nonlinear dynamics theory. A time-dependent mathematical model is established to describe the pressure distribution in the axial-grooved compressible gas-lubricated journal bearing. The time-dependent compressible gas-lubricated Reynolds equation is solved by the differential transformation method. The gyroscopic effect of the rotor supported by gas-lubricated journal bearing with three axial grooves is taken into consideration in the model of the system, and the dynamic equation of motion is calculated by the modified Wilson-θ-based method. To analyze the unbalanced responses of the rotor system supported by finite length gas-lubricated journal bearings, such as bifurcation and chaos, the bifurcation diagram, the orbit diagram, the Poincaré map, the time series and the frequency spectrum are employed. The numerical results reveal that the nonlinear gas film forces have a significant influence on the stability of rotor system and there are the rich nonlinear phenomena, such as the periodic, period-doubling, quasi-periodic, period-4 and chaotic motion, and so on. The proposed models and numerical results can provide a theoretical direction to the design of axial-grooved gas-lubricated journal bearing-rotor system. | ZHANG Yongfang HEI Di Lü Yanjun WANG Quandai MüLLER Norbert | 2014 | Chinese Journal of Mechanical Engineering2014，27，2： | 9 |
| 2 | Investigation of the influence of ultrasonic stirring on mass transfer in the through-mask electrochemical micromachining process显示文摘Surface texturing is a widely accepted approach for friction reduction between mechanical components. Through-mask electrochemical micromachining is a simple and reliable process for metal surface texturing in which mass transport conditions have profound influence on final machined quality. An ultrasonic stirrer is usually adopted for mass transfer enhancement.However, understanding of the effects of ultrasonic stirring on mass transfer is limited, and is far from sufficient for developing guidelines for its practical application. In this work, the influences of ultrasonic stirring parameters on mass transfer have been investigated numerically and experimentally. With the numerical method, periodic pressure change in the electrolyte over time has been obtained, showing that ultrasonic stirring results in drastic transient pressure change in electrolyte fluid fields. Parameters related to ultrasonic frequency, vibration amplitude, and the depth of anode surface immersed in the electrolyte solution influence pressure amplitude. Validation experiments have been conducted and etched surface profile and morphology characterized,which show that the experimental observations are in agreement with numerical predictions. With the optimized mass transfer,well-defined micro-pits array of 30 μm and a smooth etched surface on tin-bronze substrate in large scale have been demonstrated. | WANG QuanDai CAI XingXing WANG Li LI PengYang XIAO JiMing LI Yan | 2018 | Science China(Technological Sciences)2018，61，2： | 3 |
| 3 | Rapid nanopatterning technique based on monolayer silica nanosphere close-packing by spin coating显示文摘Nanoparticles monolayer formation by spin coating is considered to be a simple, fast and inexpensive nanopatterning technique. However, the parameters that govern the overall growth process in this technique are not completely quantified and techniques for the controlled and continuous growth of close packed monolayer particle arrays without defects need to be developed. In this paper, an ordered particle array formation process is analyzed theoretically, employing material flux balance and particle-subjected forces balance, based on the film thickness model of spin coating and evaporation rate law. A series of experiments were conducted using silica particle suspensions with various particle volume fractions and different spin speeds. The results show that the spin speed should match the particle volume fraction to meet the requirements of material flux and particles movement in order to obtain a close packed monolayer film. The formation mechanism of fabrication defects involving particle agglomeration and uncontrollable voids were analyzed qualitatively based on crystal growth theory, and validation experiments were performed. The formation of highly uniform close-packed monolayer films was demonstrated and the condition requirements for achieving monolayer nanoparticles array with good quality presented. | WANG QuanDai YE Lian WANG Li LI PengYang CAO Yi LI Yan | 2016 | Science China(Technological Sciences)2016，59，10： | 2 |
| 4 | Recent Progress in Cellulose-Based Flexible Sensors显示文摘Flexible sensors are attractive due to potential applications in body exercise and ambient gas monitoring systems.Cellulose and its derivatives have combined superiorities such as intrinsic and structural flexibility,ease of chemical functionalization,moisture sensitivity,and mechanical stability,enabling them to be promising candidates as flexible supporting substrates and flexible sensitive materials.Significant progress consequently has been achieved to improve mechanical,electrical,and chemical performance.The latest advance in materials synthesis,structure design,fabrication control,and working mechanism of novel cellulose-based flexible sensors are reviewed and discussed,including strain sensors,humidity sensors,and harmful gas sensors.Various strategies were summarized to enhance sensor performance by surface group modifications,inorganic and organic conducting fillers optimization,multilayer structure design.Newly emerged processing techniques of self-assembly,vacuum filtration,and 3D printing were introduced as well to construct multiscale microstructures.The integration of multiple sensors toward smart and healthy exercise monitoring system is briefly reviewed.The facing challenges and future opportunities of cellulose-based flexible sensors were discussed and proposed at the end.This review provides inspiration and guidelines on how to design and fabricate cellulose-based flexible sensors. | Ningli An Jingxuan Qin Xing Zhou Quandai Wang Changqing Fang Jiapeng Guo Bin Nan | 2022 | Journal of Renewable Materials2022，10，9： | 0 |
| 5 | A Novel Three-dimensional Microstructure Fabrication Method Based on Multilevel Imprint Lithography显示文摘 | WANG Quandai WANG Quandai DUAN Yugang DUAN Yugang LU Bingheng LU Bingheng | 2009 | Chinese Journal of Electronics2009，18，4： | 0 |
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