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Yanju Wu,Mingxiu Lv,Bei Li,Junda Ge,Lin Gao 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.3
The electrodeposition of a film of reduced graphene oxide (ERGO) with well-dispersed on a glassy carbon electrode (GCE) was achieved using cyclic voltammetry (CV) in a graphene oxide (GO) colloidal solution. Using square wave adsorptive stripping voltammetry (SWASV), the ERGO film was applied for the first time, in developing a high-sensitive electrochemical sensor for detection of taxifolin. Compared with bare GCE, the resulting electrodes (ERGO/GCE) exhibited excellent response toward the oxidation of taxifolin by significantly enhancing the oxidation peak currents and the decreased peak-to-peak separation. Under selected conditions, the reduction peak currents had linear relationship with taxifolin concentration in the range of 5.0 x 10-8 - 1.5 x 10-5 mol L-1, with detection limit of 4.0 x 10-9 mol L-1. Besides, the method was successfully applied to the quantitative determination of taxifolin in the Prince's-feather fruit with satisfactory results.
Electromechanical coupling modeling simulation and experimental study of crawler
Yanju Ji,Xueying Lv,Liu Zhang,Guanyu Zhang 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.2
The electromechanical coupling performance of crawler machinery is investigated. A dynamic equation of electromechanical coupling of crawler machinery is established under multi-typical working conditions. The variation in performance of electromechanical parameters during unstable operations over time is analyzed using the virtual prototype and electromechanical coupling model of crawler machinery. The correctness of the electromechanical coupling model is confirmed by comparing the theoretical analysis, virtual prototype simulation, and physical prototype results. This study provides accurate and valuable theoretical methods and fundamental knowledge to analyze the electromechanical and road driving performance as well as to develop and design a crawler machinery.
Sufang Chen,Yanju Qiu,Xixi Xing,Cunwen Wang,Chengchao Liu,Yuhua Zhang,Jingping Hong,Jinlin Li,Daohong Zhang 한국고분자학회 2020 Macromolecular Research Vol.28 No.3
Among the Fischer-Tropsch synthesis (FTS) catalysts, Cobalt catalysts are currently attracting a lot of research interests due to their high activity and high selectivity. But the dispersion and reducibility of cobalt catalysts with moderate interaction between cobalt and support are still a challenge. A novel amino-ended hyperbranched polyamide (AEHPA) was used to modify SBA-15 and then was applied as support for obtaining cobalt catalyst (15Co/SBA-15-N). The catalysts were characterized by XRD, TEM, XPS and H2-TPR techniques. The results showed that AEHPA doped mesoporous SBA-15 caused the generation of N species in the SBA-15 pore channels. The N-Co bonds resulted in the formation of highly-dispersed cobalt nanoparticles with uniform sizes inside the ordered mesopores of support. AEHPA doping was an effective way to modify the surface properties of the SBA-15 for immobilizing cobalt nanoparticles. Compared with the conventional 15Co/SBA-15 catalyst without doping AEHPA, the AEHPA doped 15Co/SBA-15-N catalyst showed improved cobalt dispersion and stabilized cobalt location, which led to much better reaction stability as well as C5+ selectivity.
Hongjun Liang,Yanju Jiang,Yiyan Lu,Jiyue Hu 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.37 No.4
Twenty-two corrosion-damaged columns were simulated through accelerated steel corrosion tests. Eight specimens were directly tested to failure under axial load, and the remaining specimens were tested after concrete-filled steel tube (CFST) strengthening. This study aimed to investigate the damage of RC columns after corrosion and their restoration and enhancement after strengthening. The research parameters included different corrosion degrees of RC columns, diameter-to-thickness ratio of steel tube and the strengthening concrete strength. Experimental results showed that CFST strengthening method could change the failure mode of corrosion-damaged RC columns from brittleness to ductility. In addition to the bearing capacity provided by the strengthening materials, it can also provide an extra 26.7% amplification because of the effective confinement provided by steel tubes. The influence of corrosion on reinforcement and concrete was quantitatively analysed and considered in the design formula. The proposed formula accurately predicted the bearing capacity of the strengthened columns with a maximum error of only 7.68%.
Electric field induced variation of temperature and entropy in dielectric elastomers
Liwu Liu,Jinrong Li,Yanju Liu,Jinsong Leng,Junqing Zhao,Jianwen Zhao 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.1
Dielectric elastomer is a kind of typical electro-active polymer material. Under external electric field it can produce large electrostrictiondeformation and possesses the advantages of high elastic energy density, super short response time, high efficiency, and so on. It iswidely used in the artificial muscles, facial expressions, actuators, energy harvesters, sensors, robots and Braille display devices, and alsoshows huge application potential in the aerospace and intelligent bionic areas. We built the free energy of the dielectric elastomer electrical-mechanical coupling system and investigated its constitutive relation and stability behavior. Then we calculated the elastomer’s criticaldeformation suffering from the voltage. If electrical breakdown, electromechanical instability and snap-through instability can beavoided, the large electrostriction deformation can induce adiabatic temperature change and isothermal entropy change of the dielectricelastomer. We used the entropy-temperature or electric displacement-electric field plane to describe the temperature change and entropychange of dielectric elastomer undergoing large electrostriction deformation. With the influence of temperature, we developed a temperatureand deformation coupling thermodynamical free energy model to calculate the electric field induced variation of temperature andentropy in dielectric elastomers. The results should offer great help in guiding the design and fabrication of excellent actuators featuringsoft dielectric elastomers.
Design, Drive and Control of a Novel SMA-actuated Humanoid Flexible Gripper
Yang Kai,Wang Yanjue 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.5
recovering wire w1, with remembered ‘U’ shape, is located along the rod’s axis. The restoring wire w2, with memorized straight shape, is located in parallel with the rod’ axis with an offset distance d1. Two strain gauges, arranged in complemental configuration and sticking to the rod, are used to implement accurate displacement control. Upon the elicitation of the structure of a human being’s hands, a finger with multi-units is proposed. The finger has two flexible rods with embedded SMA wires and one shorter rod as a connecting part. The number and position of fingers are investigated by making use of a nonlinear plan process with an index W, a function of grasp matrix G. The hardware of the drive and control system of the gripper has been completed on the base of a DSP chip. After the track plan is realized in the joint space through B spline interpolation method, the software of the position control system is fulfilled through two-staged slide control strategy. The simulations and experiments of step response of the SMA actuator are carried out. It is shown in the experiments that the maximum angle between ends’ tangents of each finger is 68.5, 79 and 79 degrees, respectively, and the tip of each finger could reach its final position by using approximately the same time period.
Amorphous Bimetallic Nanowires with High-Performance Microwave Absorption: A Case for FeCo Nanowires
Junyao Shen,Yongtao Yao,Yanju Liu,Jinsong Leng 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.4
Amorphous FeCo nanowires (NWs) with the average diameter of 120 nm were successfully prepared with a magnetic-field-assisted (MFA) hydrothermal method. Rapid reaction time was adopted to obtain amorphous FeCo NWs, being checked by XRD and TEM. Tuning the stoichiometric ratio of Fe/Co content meets the optimal impedance matching under different absorption frequency, making both improved intensities and frequency ranges of microwave absorption. For example, under 3mm coating thickness, the reflection loss (RL) peaks of Fe3Co7, Fe5Co5 and Fe7Co3 NWs are -25.88 dB at 4 GHz, -19.06 dB at 4.24 GHz and -21.98 dB at 5.44 GHz. The related efficient absorption bandwidths (fE < -10 dB) of Fe3Co7 NWs, Fe5Co5 NWs and Fe7Co3 NWs are 5.40 GHz, 3.52 GHz and 4.91GHz, respectively. It is ascribed to integrating enhanced dielectric/conductive losses, negligible damages from eddy current effect and good impedance matching for high-performance FeCo NWs absorbers. This work paves a new path on synthesizing bimetallic wire-like nanostructures for microwave absorption demands.