Assembly of micro/nanomaterials into complex, three-dimensional architectures by compressive buckling

Xu, Sheng,Yan, Zheng,Jang, Kyung-In,Huang, Wen,Fu, Haoran,Kim, Jeonghyun,Wei, Zijun,Flavin, Matthew,McCracken, Joselle,Wang, Renhan,Badea, Adina,Liu, Yuhao,Xiao, Dongqing,Zhou, Guoyan,Lee, Jungwoo,Chu American Association for the Advancement of Scienc 2015 Science Vol.347 No.6218

<P><B>Popping materials and devices from 2D into 3D</B></P><P>Curved, thin, flexible complex three-dimensional (3D) structures can be very hard to manufacture at small length scales. Xu <I>et al.</I> develop an ingenious design strategy for the microfabrication of complex geometric 3D mesostructures that derive from the out-of-plane buckling of an originally planar structural layout (see the Perspective by Ye and Tsukruk). Finite element analysis of the mechanics makes it possible to design the two 2D patterns, which is then attached to a previously strained substrate at a number of points. Relaxing of the substrate causes the patterned material to bend and buckle, leading to its 3D shape.</P><P><I>Science</I>, this issue p. 154; see also p. 130</P><P>Complex three-dimensional (3D) structures in biology (e.g., cytoskeletal webs, neural circuits, and vasculature networks) form naturally to provide essential functions in even the most basic forms of life. Compelling opportunities exist for analogous 3D architectures in human-made devices, but design options are constrained by existing capabilities in materials growth and assembly. We report routes to previously inaccessible classes of 3D constructs in advanced materials, including device-grade silicon. The schemes involve geometric transformation of 2D micro/nanostructures into extended 3D layouts by compressive buckling. Demonstrations include experimental and theoretical studies of more than 40 representative geometries, from single and multiple helices, toroids, and conical spirals to structures that resemble spherical baskets, cuboid cages, starbursts, flowers, scaffolds, fences, and frameworks, each with single- and/or multiple-level configurations.</P>

Adaptive robust control of active magnetic bearings rigid rotor systems

Yuhao Xu,Xiaoyuan Wang,Mingxin Liu,Na Li,Tian Yu 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.6

Aiming at the problems of diffi cult decoupling, complex controller models, and poor disturbance rejection capability caused by the inherent nonlinear and strong coupling characteristics of the active magnetic bearing (AMB), an adaptive H-infinity robust control (AHRC) method is proposed in the AMBs-rigid rotor system. The proposed method combines the active disturbance rejection control (ADRC) with the robust control to achieve stable operation of the AMBs-rigid rotor system under high-speed conditions. First, a four-degree-of-freedom (4-DOF) AMBs-rigid rotor model was established and transformed into a one-degree-of-freedom (1-DOF) model for the design of the robust controller, which weakens the coupling effect between each of the degrees of freedom (DOF). Then the multi-objective non-dominated sorting genetic algorithm II (NSGA-II) was used to fi nd the relative optimal weighting function value of the H-infinite robust control (HRC), which solved the difficulties in the design of the robust controller for known controlled system models. In addition, by combining the optimized H-infi nity robust controller with the original error feedback control rate in the ADRC, the proposed AHRC retains the strong robustness of the HRC and the decoupling capability of the ADRC, which improves the tracking performance and anti-disturbance performance of the controlled system. Simulation and experimental results verify the effectiveness of the proposed method.

Effect of activator types on cement mortar with polymeric aluminum chloride waste residue

Ping Xu,Yuhao Cui,Dong Han,Minxia Zhang,Yahong Ding Techno-Press 2023 Advances in concrete construction Vol.15 No.3

Water glass (WG) and sodium sulfate (SS) were used to prepare polymeric aluminum chloride residue cement mortar (PACRM) by single and compound blending with polymeric aluminum chloride waste residue, respectively. The structural strength and textural characteristics examinations showed that PACRM consistency increased by incorporating WG, but decreased by incorporating SS. When WG and SS were compounded, the mortar consistency initially rose before falling. The compressive strength of PACRM increased and then decreased as WG was increased. The mechanical properties of PACRM were better enhanced by SS than WG, showing no strength deterioration. The main reason for the improved mechanical properties of polymeric aluminum chloride waste residue in the presence of activators is the increased precipitation of reactive substances, such as C-S-H gels, calcium silica, and Ca(OH)₂. The density of the specimens with PACRM and the degree of aggregation of hydration products were significantly enhanced by generating more hydration products in the mortar. Further, the cracks and pores were significantly reduced, and the matrix structure was continuous and dense at 5% SS doping and 3% compound doping.

Study on Tribological Properties of Laser-Textured Plunger in Methanol Engine

Bifeng Yin,Yuhao Jiang,Bo Xu,Hekun Jia,Xuefeng Wang 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.4

Considering the eccentricity and deformation of the plunger, a lubrication model of laser-textured plunger pair was established to research friction-and-wear performance of typical surface texture on the plunger under diesel and methanol lubrication. The calculation results show that for the non-textured plunger, the oil film thickness and fluid friction under methanol lubrication are lower than diesel lubrication, and the asperity friction was greater than diesel lubrication, indicating that methanol may deteriorate the lubrication performance of the plunger surface. After texturing the plunger, the oil film thickness and fluid friction during methanol lubrication are greater than the non-textured scheme, and the asperity friction is lower than the non-textured scheme, which means that the surface texture has the potential to improve the lubrication performance of the plunger. The friction and wear tests results indicate that the average friction coefficient of the textured plunger is reduced by 3.4 ~ 6.2 % compared with the non-textured plunger in methanol lubrication. The lubrication performance of the textured plunger during methanol lubrication reaches the level of the non-textured plunger in diesel lubrication. After the wear test, the surface wear depth of the textured plunger is reduced by 16.2 % compared with the non-textured plunger in methanol lubrication condition.

基于新型冠状病毒疫情背景下的中国电子商务行业发展研究

张,昱昊(Yuhao Zhang),徐吉霖(Jilin Xu) 동아시아무역학회 2020 Journal of East Asian Trade(JEAT) Vol.2 No.2

本研究的目的是分析新冠状病毒肺炎疫情对中国电子商务行业的影响,并针对研究提出合理的经营策略,为中国电子商务的未来发展提出参考性建议。本研究的研究方法主要是以文献数据为主,对电子商务的相关文献和数据进行分析。根据本研究的研究结果得知依靠网络通信技术的电子商务已经逐渐发展成熟稳定,但随着新冠状病毒肺炎疫情的扩散,电子商务出现了供应链断裂和资金链短缺等问题。本研究的意义在于对新冠疫情下电商行业制定积极有效的措施促进电商行业的可持续发展。 但在本研究的研究过程中发现根据电商企业规模的不同,受新冠状病毒肺炎疫情的影响也不同,所以后续研究中以中国中小型电商企业为调查对象进行问卷调查,根据数据反馈找出疫情对电商企业的影响,作为本研究数据补充。 Purpose - The purpose of this study is to analyze the impact of the COVID-19 on China’s e-commerce industry, and to put forward reasonable management strategies for the future development of e-commerce in China. Design/Methodology/Approach -The research method of this study is mainly based on literature data, and analyzes the relevant literature and data of electronic commerce. Findings - According to the research results of this study, it is known that e-commerce relying on network communication technology has gradually developed mature and stable, but with the spread of COVID-19, e-commerce has problems such as supply chain breakage and shortage of capital chain. Research Implications - In the management of this paper, this study is of great significance to the development of e-commerce in China in the future.

Highly Sensitive Optical-fiber Humidity Sensor Based on Nafion-PVA Sol-gel

Ning Wang,Yuhao Li,Xiaolei Yin,Wenting Liu,Shiqi Liu,Liang Xu,Xuwei Zhao,Yanxi Zhong 한국광학회 2023 Current Optics and Photonics Vol.7 No.1

ADAPTABILITY OF LASER TEXTURED LINER TO THE EFFECTS OF METHANOL DILUTING OIL ON TRIBOLOGICAL PROPERTIES

Jia He Kun,Xu Bo,Yin Bifeng,Jiang Yuhao,Hu Nanrong 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.2

With the increase of methanol diluting lubrication oil, the dynamic viscosity of the mixture presents a downward trend, the total acid number grows while the total base number declines, and the corrosion degree of copper strip upgrades, which indicates that methanol dilution has negative effects on lubrication and anti-corrosion performance of oil. According to ball-on-plate friction test results, the friction coefficient and surface wear of this pair increase in turn with the rising methanol dilution rate, which tends to deteriorate the tribological performance of key friction pairs in methanol engine. After laser surface texturing cylinder liner, the friction coefficient of ring/liner pair is reduced, and the anti-friction effect is enhanced with the rising methanol dilution rate, because the oil storage capacity of textured micro-dimples on liner surface can improve the lubrication of ring/liner pair and reduce asperity contact. Moreover, the micro-dimples can store debris generated in the reciprocating friction process of this pair, so as to alleviate surface wear caused by abrasive wear, and improve the wear resistance of cylinder liner. Therefore, laser texturing cylinder liner can compensate the deterioration of friction and wear performance of ring/liner pair caused by methanol diluting oil with good lubrication adaptability.

Simulation of Impact Toughness with the Effect of Temperature and Irradiation in Steels

Chenchong Wang,Jinliang Wang,Yuhao Li,Chi Zhang,Wei Xu 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.1

One of the important requirements for the application of reduced activation ferritic/martensitic steel is toretain proper mechanical properties in irradiation and high temperature conditions. In order to simulatethe impact toughness with the effect of temperature and irradiation, a simulation model based on energybalance method consisted of crack initiation, plastic propagation and cleavage propagation stages wasestablished. The effect of temperature on impact toughness was analyzed by the model and the trend ofthe simulation results was basicly consistent with the previous experimental results of CLAM steels. Theload-displacement curve was simulated to express the low temperature ductile-brittle transition. Theeffect of grain size and inclusion was analyzed by the model, which was consistent with classicalexperiment results. The transgranular-intergranular transformation in brittle materials was alsosimulated.

A Game Theory Based Interaction Strategy between Residential Users and an Electric Company

Jidong Wang,Kaijie Fang,Yuhao Yang,Yingchen Shi,Daoqiang Xu,Shuangshuang Zhao 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.1

With the development of smart grid technology, it has become a hotspot to increase benefits of both residential users and electric power companies through demand response technology and interactive technology. In this paper, the game theory is introduced to the interaction between residential users and an electric company, making a mutually beneficial situation for the two. This paper solves the problem of electricity pricing and load shifting in the interactive behavior by building the game-theoretic process, proposing the interaction strategy and doing the optimization. In the simulation results, the residential users decrease their cost by 11% mainly through shifting the thermal loads and the electric company improves its benefits by 5.6% though electricity pricing. Simulation analysis verifies the validity of the proposed method and shows great revenue for the economy of both sides.

A Game Theory Based Interaction Strategy between Residential Users and an Electric Company

Wang, Jidong,Fang, Kaijie,Yang, Yuhao,Shi, Yingchen,Xu, Daoqiang,Zhao, Shuangshuang The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.1

With the development of smart grid technology, it has become a hotspot to increase benefits of both residential users and electric power companies through demand response technology and interactive technology. In this paper, the game theory is introduced to the interaction between residential users and an electric company, making a mutually beneficial situation for the two. This paper solves the problem of electricity pricing and load shifting in the interactive behavior by building the game-theoretic process, proposing the interaction strategy and doing the optimization. In the simulation results, the residential users decrease their cost by 11% mainly through shifting the thermal loads and the electric company improves its benefits by 5.6% though electricity pricing. Simulation analysis verifies the validity of the proposed method and shows great revenue for the economy of both sides.