The preparation of alginate–AgNPs composite fiber with green approach and its antibacterial activity

Xihui Zhao,Qun Li,Xiaomei Ma,Wanying Liu,Jianping Wang,Yanzhi Xia 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.24 No.-

Antibacterial alginate fibers containing silver nanoparticles (AgNPs) have been prepared in this work. Firstly, AgNPs colloid solution was obtained employing alginate as stabilizing agent and glucose as reducing agent. Then, sodium alginate powder was directly added to the above solution and the resultant sodium alginate–AgNPs spinning dope was spun to prepare alginate–AgNPs composite fibers. The fibers were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and thermal gravimetric analysis (TG). Mechanical properties of the fibers were also measured. The antimicrobial properties were investigated by Staphylococcus aureus and Escherichia coli, and the results indicated that the composite fibers showed strong antibacterial activity.

Fault identification method for planetary gear based on DT-CWT threshold denoising and LE

Xihui Chen,Gang Cheng,Hongyu Li,Yong Li 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.3

Planetary gear is widely used in large-scale complex mechanical systems. However, because of the particularity of planetary gear transmission, serious wear and fatigue crack failures often occur in the sun gear, planet gears, and inner gear ring. In addition, every type of fault will experience different degradation processes. Improving the operation reliability of mechanical equipment through fault diagnosis of planetary gears and monitoring their degradation process is beneficial. This paper proposes a planetary gear fault identification method based on Dual-tree Complex wavelet transform (DT-CWT) threshold denoising and Laplacian eigenmaps (LE). The noise reduction processing of the original signal is achieved by the DT-CWT threshold denoising method, which takes full advantage of DT-CWT and is combined with the wavelet threshold of rigrsure principle. The original high-dimensional feature set, including the time domain features, frequency domain features, permutation entropy, and fractal box dimension of the denoised signal, is constructed from multiangles. To solve the problems of excessively large feature dimension and the existence of redundant information, the LE algorithm is used to reduce the dimension of the original high-dimensional feature set, and the low-dimensional sensitive features are obtained. Through the above method, the effective identification of different fault states and different degradation states of the planetary gear are achieved.

Diagnosing planetary gear faults using the fuzzy entropy of LMD and ANFIS

Xihui Chen,Gang Cheng,Hongyu Li,Min Zhang 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.6

The small size, low weight, and large transmission ratio of planetary gear have resulted in large-scale use, low speed, and heavy-duty mechanical systems. Poor working conditions of planetary gear lead to frequent occurrence of faults. A method is proposed for diagnosing faults in planetary gear based on fuzzy entropy of Local mean decomposition (LMD) and Adaptive neuro-fuzzy inference system (ANFIS). The original vibration signal is decomposed into six Product function (PF) components and a residual using LMD. Given that decomposed PF components contain the main fault feature information, fuzzy entropy is used to reflect the complexity and irregularity of each PF component. The fuzzy entropies of each PF component are defined as the input of the ANFIS model, and its parameters and membership functions are adaptively adjusted based on training samples. Finally, fuzzy inference rules are determined, and the optimal ANFIS model is obtained. Testing samples are used to verity the trained ANFIS model. The overall fault recognition rate reaches 88.8%, and the fault recognition rate for gear with wear reaches 96%. Therefore, the proposed method is effective at diagnosing planetary gear faults.

Tall Buildings as Urban Habitats: A Quantitative Approach for Measuring Positive Social Impacts of Tall Buildings' Lower Public Space

Zhou, Xihui,Ye, Yu,Wang, Zhendong Council on Tall Building and Urban Habitat Korea 2019 International journal of high-rise buildings Vol.8 No.1

After decades of high-speed development, designing tall buildings as critical components of urban habitat, rather than simply standing aloof from their environments, has become an important concern in many Asian cities. Nevertheless, the lack of quantitative understanding cannot support efficient architectural design or urban renewal that targets better place-making. This study attempts to fill the gap by providing a typological approach for measuring the social impact of tall buildings' ground conditions: that is, public space, podiums, and interfaces. The central business districts (CBD) of three Asian cities, Shanghai, Hong Kong, and Singapore, were selected as cases. Typical patterns and categories of lower-level public spaces among the three CBDs were abstracted via typological analyses and field study. The following evaluation is achieved through the analytic hierarchy process (AHP). This quantified approach helps to provide a visualization of high or low positive social impacts of tall buildings' lower-level public spaces among the three cases. This study also helps to suggest a design code for tall buildings aimed at a more human-oriented urban habitat.

滿文篆字舛誤硏究

황석혜 ( Huang Xihui ) 한국알타이학회 2017 알타이학보 Vol.0 No.27

Manchu is one of the few minorities in the history of China which created texts. It created a 32 Fonts of Manchu seal characters and used 10 fonts in making Royal Seals in Qing Dynasty, in combiniation with Han seal characters. Such combination marks the greatest development in the history of making royal seals, but still there are some errors in matching perfectly the Manchu and Han seal charaters in making royal seals, and such errors can ben found even in Eulogy of Mukden by Emperor Qianlong and the inscriptions on top part of some steles. This paper identifies the errors in sampled royal seals, studies the causes, and suggest the corrections. This reserch is a contribution to a comprehensive, accurate and objective evaluation to the historical and cultural significance of Manchu seal characters, and it also benefits the studies on Manchu seal characters and Royal Seals in Qing Dynasty, as well as the further development of ethnic art and culture in contemporary China. The researcher calls the academic community to pay attention to the profound significance of Manchu seal characters, and propose earnestly the objective, rigorous and scientific study method in Manchu language studies.

Model-based analysis and fault diagnosis of a compound planetary gear set with damaged sun gear

Guoyan Li,Xihui Liang,Fang-Yi Li 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.7

The vibration properties of compound planetary gears are more complicated than that of simple ones. This paper aims to investigate the fault properties of a compound planetary gear set in chipped sun gear conditions using model-based method. A three-dimensional lumped-parameter nonlinear dynamic model for the compound planetary gear set is established. This model considers the time-varying mesh stiffness (TVMS), the mesh phase relations, and gear chipping defects. The analytical equations are derived to quantify the TVMS reduction induced by the chipped gear based on the improved potential energy method. Further, the simulations are performed to demonstrate the fault features of sun gears with single or multiple chipped teeth in different gear stages. Moreover, the theoretical derivations are validated through the experimental signals analysis.

Microstructure and Magnetic Properties of Plasma-Sprayed Fe<SUB>73.5</SUB>Cu1Nb₃Si<SUB>13.5</SUB>B₉ Coatings

Xiaojun Ni,Xihui Bo,Jiawei Wu,Jinhua Guo,Zhichao Lu,Shaoxiong Zhou 한국자기학회 2010 한국자기학회 학술연구발표회 논문개요집 Vol.2010 No.12

Natural frequency analysis and experiment for 3SPS+1PS parallel hip joint manipulator based on rigid-flexible coupling theory

Songtao Wang,Gang Cheng,Xihui Chen,Jianhua Yang 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.3

For analyzing natural frequency of a 3SPS+1PS parallel hip joint manipulator, a rigid-flexible coupling theory is proposed. 3SPS denotes that the PHJM has three legs and each leg type is SPS. 1PS denotes that the PHJM has one constrained leg and the constrained leg type is PS. The rigid finite element method and flexible finite element method are the base of the rigid-flexible coupling theory. Firstly, the basic element models of the PHJM are established based on the rigid-flexible coupling analysis. Secondly, the elastic dynamic models of the flexible legs are established based on the Lagrange equation and flexible finite method. Finally, the rigid-flexible coupling model of the PHJM is assembled by building the relationship between the rigid and flexible elements. Based on the rigid-flexible model, the natural frequency of the PHJM is analyzed. In addition, the effect parameters of the natural frequency are analyzed. The analysis results of the natural frequency show that the natural frequency is symmetric distribution in the working space, and the minimum value of the 1 st order natural frequency is 2.3 Hz. The operating frequency (1 Hz) is much lower than the 1 st order natural frequency, so the PHJM will not generate resonance and can operate stably. The analysis results of the parameter show that the PHJM has the minimal sensitivity with the effect parameter E and has the maximal sensitivity with the effect parameter H, so the length of the middle leg has the biggest impact on the natural frequency. Natural frequency analysis results have been checked by the hammer test, which verifies the feasibility of the rigid-flexible coupling theory. At the same time, the regression analysis is carried out based on the hammer test results. Using the rigid-flexible coupling theory to solve the natural frequency of the parallel manipulator, the physical meaning is explicit and the modeling process is clear, so the rigid-flexible coupling theory is a universal method.

인 첨가에 인한 바이오 세라믹 여과에 의한 유기물 제거 개선

Sang, Junqiang,Zhang, Xihui,Li, Lingzhi,Wang, Zhansheng 한국수처리학회 2004 한국수처리학회지 Vol.12 No.2

Cuprous Oxide Films with Hollow Cubic Cage Structure for Nonenzymatic Glucose Detection

Fang Sun,Lehong Xing,Xihui Yang,Hailiang Huang,Lina Ning 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.4

In this study, CuO films with hollow cubic cages were prepared by a facile two-step procedure consisting of electrodeposition synthesis and subsequent direct calcination. First, Cu2O nanocubes were fabricated on ITO substrate through a simple electrodeposition procedure. Then, Cu2O nanocubes were converted to CuO hollow cubic cages without obvious morphological change through direct calcination. The obtained CuO cubic cages serving as active materials illustrated a favorable performance for nonenzymatic glucose sensing with high sensitivity of 2117.44 μA mM -1 cm -2 at a low applied potential of 0.50 V, fast-response time (less than 3 s), low detection limit of 1.0 μM and wide linear range up from 2.0 μM to 1.0 mM (R2 = 0.9983). Moreover, the good selectivity of the CuO cubic cages-based nonenzymatic glucose sensor against electroactive compounds such as ascorbic acid, uric acid and dopamine were also demonstrated. These good features indicate that the as-prepared CuO cubic cages can be used as promising electrode materials, which have a great potential in the development of sensitive and selective nonenzymatic glucose sensors.