Facile hydrothermal synthesis of ultrahigh-aspect-ratio V2O5 nanowires for high-performance supercapacitors

Nannan Wang,Yifu Zhang,Tao Hu,Yunfeng Zhao,Changgong Meng 한국물리학회 2015 Current Applied Physics Vol.15 No.4

Ultrahigh-aspect-ratio V2O5 nanowires were successfully prepared using [VO(O2)2(OH2)]- as the starting material by a template-free hydrothermal route without the addition of organic surfactant or inorganic ions. The prepared samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmet-Teller (BET), cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD). The results revealed that the peroxovanadium (V) complexes can be easily transformed to V2O5 nanowires by this hydrothermal route. The uniform nanowires were with width about 50 nm and length about dozens of micron. The BET analysis showed the V2O5 nanowires had a high specific surface area of 25.6 m2 g-1. The synthesized V2O5 nanowires performed a high capacitance of 351 F g-1 when used as supercapacitor electrode in 1 mol L-1 LiNO3.

A Novel Filtering Method Based on a Nonlinear Tracking Differentiator for the Speed Measurement of Direct-drive Permanent Magnet Traction Machines

Wang, Gaolin,Wang, Bowen,Zhao, Nannan,Xu, Dianguo The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.2

This paper presents a novel filtering method for speed measurements to improve the low-speed performance of the direct-drive permanent magnet traction machines for elevators. Based on the theory of nonlinear tracking differentiator (NTD), this method, which can act as a high performance filter of a raw speed signal, obtains a more accurate speed feedback signal when applying a low-resolution encoder. In addition, it can relieve the interference caused by the position derivative for speed sampling. By analyzing the frequency response of the NTD, the influence of its parameters on the performance of the speed filtering is investigated. Compared with different types of low-pass filters, the proposed method shows a shorter time delay and a stronger ability in terms of noise suppression when the parameters are selected carefully. In addition, when using the measured speed signal through a nonlinear tracking differentiator as the feedback of the system, the motor runs more steadily at low speeds. As a result, the riding comfort of a direct-drive elevator can be improved. The feasibility of the proposed strategy was verified on an 11.7kW elevator traction machine using a commercial inverter.

청년층 감성을 고려한 도서관 체험 공간 디자인 연구

왕남남(Wang Nannan),종유지아(Zhong Yujia),남경숙(Nam Kyoung-sook) 한국실내디자인학회 2018 한국실내디자인학회 학술대회논문집 Vol.20 No.1

With the development of the times, the library is becoming a comprehensive service center, it has various functions which includes integrating exhibition, academic exchange, specification research, study and others. At the same time, the traditional mode of book retrieval is being replaced by the use of information technology. During promoted the change of library reading space period, the design model of reading space is also be influenced. Modern library space design focus more on the user experience and that is still valued user-oriented to build a warm, convenient reading and viewing environment. The analysis is carried out by means of 2 spatial cases. this study are: A(Hyundai Card Music Library),B(Hyundai Card Cooking Library). Through the case, we have drawn three conclusions. First, emotional design of space from four library by three aspects including experience, interaction, continuity. It deeper into explore the customer-centric sensual design, which provide a good reference for future library design. Second, TThe library`s spatial function is designed from the user`s point of view, which combines the space and the sensory experience to make the library"s perceptual effect become larger.

Parameters Design and Braking Efficiency Analysis of a Hydraulic Self-Energizing Wedge Disc Brake

Junnian Wang,Yao Zhang,Nannan Yang,Dafeng Song,Qingnian Wang 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.10

Pursuing more efficient running and operation has been the orientation of today's automotive powertrain and chassis technologies development. As for the brake system, increasing the braking efficiency or reducing the power consumption of actuation is an effective method to improve the energy-saving performance of the car. In this paper, a self-energizing wedge disc brake actuated by hydraulic power, that could be used to reduce both the actuation force and the energy required for braking is presented and compared in terms of the practical issues on braking efficiency, heat recession and self-locking. The selected critical parameters and their optimum value range are determined based on the static force analysis. Then the simulations based on AMESim/Simulink are implemented to compare the proposed wedge brake with traditional disc brake, and to investigate the influence of the wedge angle and the actuating angle on the braking efficiency performance. The simulation results validate the self-reinforcement and energy saving performance of this hydraulic wedge disc brake well.

A Novel Filtering Method Based on a Nonlinear Tracking Differentiator for the Speed Measurement of Direct-drive Permanent Magnet Traction Machines

Gaolin Wang,Bowen Wang,Nannan Zhao,Dianguo Xu 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.2

This paper presents a novel filtering method for speed measurements to improve the low-speed performance of the direct-drive permanent magnet traction machines for elevators. Based on the theory of nonlinear tracking differentiator (NTD), this method, which can act as a high performance filter of a raw speed signal, obtains a more accurate speed feedback signal when applying a low-resolution encoder. In addition, it can relieve the interference caused by the position derivative for speed sampling. By analyzing the frequency response of the NTD, the influence of its parameters on the performance of the speed filtering is investigated. Compared with different types of low-pass filters, the proposed method shows a shorter time delay and a stronger ability in terms of noise suppression when the parameters are selected carefully. In addition, when using the measured speed signal through a nonlinear tracking differentiator as the feedback of the system, the motor runs more steadily at low speeds. As a result, the riding comfort of a direct-drive elevator can be improved. The feasibility of the proposed strategy was verified on an 11.7kW elevator traction machine using a commercial inverter.

백화점에 휴게공간 활성화 방안 연구

왕남남(Wang Nannan),남경숙(Nam Kyoung-sook) 한국실내디자인학회 2017 한국실내디자인학회 학술대회논문집 Vol.2017 No.10

With the rapid development of the society, the standard of living of people has improved at large. People’s consumption concept have been increasingly diversified. The space layout has growing influence for customer behavior. Therefore, the emporium in order to cater consumer to improve the design in the space layout. This report will propose a breathing space versatility of the improvement project by investigating the emporium breathing space research. The places of this study: Shinsegae Department Store, Lotte Department Store, Hyundai Department Store. Through the case, we have drawn three conclusions. Firstly, the both of the design of breathing space and the topic of sale space should have consistent and distinguish. Secondly, during the design of the breathing space, the materials, color and illumination factors use should be considered for the preferences of different age consumers to reach space diversity. Thirdly, the integrality of space function not only can satisfy customers’ requirements, but also it can achieve publicity traffic effect.

외국어로서의 중국어 교육의 변천과 그 특징

왕난난(Nannan Wang),임태성(Taesung Lim) 한국사회언어학회 2023 사회언어학 Vol.31 No.1

Chinese as a foreign language education is one of China's crucial national and governmental strategy. Over the past 70 years of development, Chinese as a foreign language education has made remarkable achievements, but it faces great challenges. In China, the term Chinese as a Foreign Language Education is the last in a series of terms from Teaching Chinese as a Foreign Language to Teaching Chinese to Speakers of Other Languages and then to International Chinese Language Education, and in its development has passed from the 1.0 era to the 4.0 era. This article aims to present new goals by examining the achievements and characteristics of Chinese as a foreign language education step by step from the perspective of governance and drawing out their implications, identifying the causes of its development, and forecasting future tasks.

Thermo-optic Characteristics of Micro-structured Optical Fiber Infiltrated with Mixture Liquids

Ran Wang,Yuye Wang,Yinping Miao,Ying Lu,Nannan Luan,Congjing Hao,Liangcheng Duan,Cai Yuan,Jianquan Yao 한국광학회 2013 Current Optics and Photonics Vol.17 No.3

We present both theoretically and experimentally the thermo-optic characteristics of micro-structured optical fiber (MOF) filled with mixed liquid. The performance of MOF depends on the efficient interaction between the fundamental mode of the transmitted light wave and the tunable thermo-optic materials in the cladding. The numerical simulation indicates that the confinement loss of MOF presents higher temperature dependence with higher air-filling ratios d/Λ, longer incident wavelength and fewer air holes in the cladding. For the 4cm liquid-filled grapefruit MOF, we demonstrate from experiments that different proportions of solutions lead to tunable temperature sensitive ranges. The insertion loss and the extinction ratio are 3~4 dB and approximate 20 dB, respectively. The proposed liquid-filling MOF will be developed as thermo-optic sensor, attenuator or optical switch with the advantages of simple structure, compact configuration and easy fabrication.

Molecular genetic characterization of rice seed lipoxygenase 3 and assessment of its effects on seed longevity

Qizhang Long,Wenwei Zhang,Peng Wang,Wenbiao Shen,Tong Zhou,Nannan Liu,Ren Wang,Ling Jiang,Jiexue Huang,Yihua Wang,Yuqiang Liu,Jianmin Wan 한국식물학회 2013 Journal of Plant Biology Vol.56 No.4

Lipoxygenases (LOXs) are enzymes involved in lipid peroxidation. Here we reported the identification, molecular and functional characterization of the gene encoding rice (Oryza sativa L.) seed LOX3 (sLOX3). Via a map-based cloning strategy we identified Os03g0700400 as the candidate gene encoding sLOX3. Further functional complementary test and biochemical characterization of the recombinant Os03g0700400 protein verified the identification. The sLOX3 gene was highly expressed in roots, moderately in embryos and very weakly in leaves, leaf sheaths and stems. Transient expression experiment (in rice protoplasts) and subsequent laser confocal microscopic analysis demonstrated that the sLOX3 protein was localized into the cytosol. We next showed that overexpression of sLOX3 in a japonica sLOX3-normal rice cultivar, Wuyunjing 7 accelerated the decrease of seed germination ability when the seeds were routinely stored, which demonstrated that sLOX3 had a negative effect on seed longevity (storability). Meanwhile, an increased occurrence of embryo decay was observed in the same transgenic seeds, suggesting that sLOX3 might negatively affect seed longevity by facilitating colonization of particular seed pathogens. Our result forwarded the understanding of the effects of 9-LOX on rice seed longevity.

Bifurcation analysis of combustion instability in a Rijke burner with an improved third-order saturated flame model

Nannan Dang,Wei Wang,Jiazhong Zhang,Yan Liu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.8

The bifurcation analysis of nonlinear combustion instability in a Rijke burner is studied numerically. First, a saturated flame model and a third-order saturated flame model are proposed, and the mode truncation effects are investigated by studying their influences on system eigenvalues. Then, bifurcation analysis on the flame location, average flame intensity, damping, and time delay in the flame model is conducted with the new flame models. Results show that the burner driven by the saturated model loses stability via supercritical Hopf bifurcations, whereas the system driven by the third-order saturated model shows the characteristic of subcritical Hopf bifurcations, accompanied by bistable regimes emerging in the bifurcation diagrams. Finally, the effects of velocity perturbations are analyzed further, and the results show that a given system may oscillates with different frequencies if the disturbance is imposed to different Galerkin modes. This study reveals that the process of the combustion system’s transition to instability depends strongly on the nonlinear term in the flame model.