Bond Behavior Between Steel Fiber Reinforced Polymer (SRP) and Concrete

Xingxing Zou,Lesley H. Sneed 한국콘크리트학회 2020 International Journal of Concrete Structures and M Vol.14 No.5

Steel fiber reinforced polymer (SRP) composite materials, which consist of continuous unidirectional steel wires (cords) embedded in a polymeric matrix, have recently emerged as an effective solution for strengthening of reinforced concrete (RC) structures. SRP is bonded to the surface of RC structures by the same matrix to provide external reinforcement. Interfacial debonding between the SRP and concrete is a primary concern in this type of application. This study aimed to investigate the bond characteristics between SRP and concrete determined by single-lap direct shear tests with different composite bonded lengths and fiber sheet densities (cord spacings). Specimens with medium density fibers failed mainly due to composite debonding, whereas those with low density fibers failed due to fiber rupture. Results of specimens that exhibited debonding were used to determine the bond-slip relationship of the SRP-concrete interface and to predict the full-range load response, which was in good agreement with the experimental results. A database of SRP-concrete direct shear tests reported in the literature was also established. Four analytical equations derived for fiber reinforced polymer (FRP)-concrete debonding were evaluated based on the database results and were found to predict the maximum load within approximately 15% error on average, however, they all underestimated the effective bond length.

Stability in the energy space of the sum of $N$ peakons for a Camassa-Holm-type equation with quartic nonlinearity

Xingxing Liu 대한수학회 2019 대한수학회보 Vol.56 No.3

Considered herein is the orbital stability in the energy space $H^1(\R)$ of a decoupled sum of $N$ peakons for a Camassa-Holm-type equation with quartic nonlinearity, which admits single peakon and multi-peakons. Based on our obtained result of the stability of a single peakon, then combining modulation argument with monotonicity of local energy $H^1$-norm, we get the stability of the sum of $N$ peakons.

Multiple Tolerances and Dye Decolorization Ability of a Novel Laccase Identified from Staphylococcus Haemolyticus

Xingxing Li,Dongliang Liu,Zhaowei Wu,Dan Li,Yifei Cai,Yao Lu,Xin Zhao,Huping Xue 한국미생물·생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.4

Laccases are multicopper oxidases with important industrial value. In the study, a novel laccase gene (mco) in a Staphylococcus haemolyticus isolate is identified and heterologously expressed in Escherichia coli. Mco shares less than 40% of amino acid sequence identities with the other characterized laccases, exhibiting the maximal activity at pH 4.0 and 60oC with 2,2'-azino-bis (3- ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) as a substrate. Additionally, the Mco is tolerant to a wide range of pH, heavy metal ions and many organic solvents, and it has a high decolorization capability toward textile dyes in the absence of redox mediators. The characteristics of the Mco make this laccase potentially useful for industrial applications such as textile finishing. Based on BLASTN results, mco is found to be widely distributed in both the bacterial genome and bacterial plasmids. Its potential role in oxidative defense ability of staphylococci may contribute to the bacterial colonization and survival.

Ordered porous TiO2 films obtained by freezing and the application in dye sensitized solar cells

Xingxing Wang,Bingchu Yang,Kechao Zhou,Dou Zhang,Zhiyou Li,Conghua Zhou 한국물리학회 2015 Current Applied Physics Vol.15 No.5

TiO2 films with ordered porous structure were prepared by freezing. By simply freezing wet TiO2 film on a cold copper plate, ice crystals could grow from bottom of film. Removing such ice crystals then led to ordered, micro-sized pores in the films. With assistance of scanning electron microscopy and N2 adsorptionedesorption isotherms, micro-structural properties of the films were studied. Coarsening behavior of ice crystals was analyzed based on evolvement of the micro-structure. It was found that, both larger film thickness and longer freezing time were beneficial for the formation of ordered porous structure, which was caused by enhanced ice crystals growth. The films were then used to fabricate photoanode of dye sensitized solar cells, of which the photo-to-electric power conversion efficiency was evaluated. It was observed that, solar cell made of ordered porous TiO2 film came out with 13% larger photo-current density comparing to that made of conventional doctor blading method, which is due to the enhanced light scattering by the ordered porous structure.

Extended State Observer Based on ADRC of Linear System with Incipient Fault

Xingxing Hua,Da-Rong Huang,Shenghui Guo 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.6

Owing to the fact that it is difficult to find the incipient fault and it is hard to deal with the disturbance, an extended state observer (ESO), which is based on the linear time invariant system is designed and analyzed. This method can effectively separate incipient fault as a new state variable from the disturbance. By using coordinate transformations, the original system is decoupled into two subsystems. Especially, an adaptive observer of faulty system is designed for the one subsystem with the incipient fault but not relevant to the disturbance, and an extended state observer (ESO) based on active disturbance rejection control (ADRC) is designed for the other one which not only has the disturbance but also the incipient fault. Two simulation results are presented to show the effectiveness of the presented methods.

Mediation analysis of leisure activities on the association between cognitive function and mortality: a longitudinal study of 42,942 Chinese adults 65 years and older

Xingxing Chen,Wenfan Wu,Xian Zhang,Tingxi Long,Wenyu Zhu,Rundong Hu,Xurui Jin,Lijing L. Yan,Yao Yao 한국역학회 2022 Epidemiology and Health Vol.44 No.-

study aimed to evaluate whether leisure activities causally mediate these associations. METHODS This longitudinal study included 42,246 participants aged over 65 years from the Chinese Longitudinal Healthy Longevity Survey. The Mini-Mental State Examination and a self-reported scale were used to measure cognitive status and leisure activities, respectively. We examined the associations of cognitive function and leisure activities with mortality using Cox proportional hazards models. Causal mediation analysis was used to assess whether leisure activities mediated the association between cognitive function and mortality. RESULTS Cognitive function and leisure activities were inversely associated with mortality. Leisure activities accounted for 28.3% (95% confidence interval [CI], 25.6 to 31.1) of the total effect of cognitive function and mortality. A higher mediated proportion (PM) was observed for physical leisure activities (PM, 20.1%; 95% CI, 18.0 to 22.3) than for social leisure activities (PM, 17.7%; 95% CI, 15.7 to 19.7). The mediating effect was higher among participants at younger ages (PM, 41.5%; 95% CI, 21.3 to 65.4), those with higher education levels (PM, 30.5%; 95% CI, 25.3 to 36.2), and residents of rural China (PM, 42.5%; 95% CI, 25.4 to 62.5). CONCLUSIONS Cognitive function was associated with inverse mortality. Leisure activities significantly mediated this association. Participation in leisure activities at the early stages of mild cognitive impairment could reduce the risk of mortality, which has a major impact on interventional strategies for healthy aging.

Analysis of the Relations between Chinese Aircraft Carriers and the Maritime Order of the South China Sea

Xingxing Wang,Jiyong Zheng 한국국방연구원 2022 The Korean Journal of Defense Analysis Vol.34 No.3

China has gradually shifted its geopolitical focus from land-based control to seabased developments out of both security and economic considerations. Marked by the official launch of its aircraft carriers a decade ago, China has dedicated resources to building up its navy as a blue water force rather than the offshore defensive force that it had primarily been until that point. Meanwhile, by serving as the pillar of sea power, these aircraft carriers will play more important roles in China’s naval development, ultimately reshaping the global strategic picture of sea power. This article aims to explore the influence of Chinese aircraft carriers to maritime order of the South China Sea and strategic pattern of global sea power by analyzing the Chinese aircraft carrier fleet’s operational design and the reconstruction of China’s naval strategy. The presence of Chinese aircraft carriers in the South China Sea and their inherent combat capabilities has inevitably casted a subversive light on the region and brought the attention of the United States’ and other regional actors’ own activities and strategies for the region. This research has great significance for understanding China's grand strategic conception and practice on the South China Sea issue as well as the construction of a new maritime order in the context of China–U.S. competition.

Mediation analysis of leisure activities on the association between cognitive function and mortality: longitudinal study of 42,942 Chinese adults 65 years and older

Chen Xingxing,Zhang Xian,Long Tingxi,Wu Wenfan,Hu Rundong,Jin Xurui,Yan Lijing L,Yao Yao,Wenyu Zhu 한국역학회 2022 Epidemiology and Health Vol.44 No.-

OBJECTIVES: Previous studies have established associations of cognitive function and leisure activities with mortality. This study aimed to evaluate whether leisure activities causally mediate these associations. METHODS: This longitudinal study included 42,246 participants aged over 65 years from the Chinese Longitudinal Healthy Longevity Survey. The Mini-Mental State Examination and a self-reported scale were used to measure cognitive status and leisure activities, respectively. We examined the associations of cognitive function and leisure activities with mortality using Cox proportional hazards models. Causal mediation analysis was used to assess whether leisure activities mediated the association between cognitive function and mortality. RESULTS: Cognitive function and leisure activities were inversely associated with mortality. Leisure activities accounted for 28.3% (95% confidence interval [CI], 25.6 to 31.1) of the total effect (TE) of cognitive function and mortality. A higher mediated proportion (PM) was observed for physical leisure activities (PM, 20.1%; 95% CI, 18.0 to 22.3) than for social leisure activities (PM, 17.7%; 95% CI, 15.7 to 19.7). The mediating effect was higher among participants at younger ages (PM, 41.5%; 95% CI, 21.3 to 65.4), those with higher education levels (PM, 30.5%; 95% CI, 25.3 to 36.2), and residents of rural China (PM, 42.5%; 95% CI, 25.4 to 62.5). CONCLUSIONS: Cognitive function was associated with inverse mortality. Leisure activities significantly mediated this association. Participation in leisure activities at the early stages of mild cognitive impairment could reduce the risk of mortality, which has a major impact on interventional strategies for healthy aging.

Design-oriented fast response voltage mode buck converter with adaptive ramp control

Peng, Xingxing,Li, Changgeng The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.5

This paper proposes a new adaptive ramp voltage mode control scheme. Instead of using the conventional slow compensation path of the voltage mode, the proposed scheme adds an extra feedback path to adjust the amplitude and DC-offset of the ramp signal and to directly accelerate the duty cycle according to the output voltage variation. In addition, a design-oriented analytical method is adopted to intuitively analyzes the loop characteristics and provides accurate instructions for the implementation and optimization of the compensator. A 5-1 V buck converter is implemented in the proposed adaptive ramp control scheme with optimized compensation. Simulation and measurement results show that the converter achieves a bandwidth of up to 591 kHz with a 3 MHz switching frequency and a 65° phase margin. In addition, the undershoot voltage and the recovery time are 16 mV and 19 ㎲ with a load change from 0.5 to 1 A. The proposed control scheme shows superior transient response performance while maintaining fixed frequency operations with a simple system structure.

Research on the Construction of Agricultural and Forestry Product Channels for Rural Revitalization

何星星(Xingxing HE),王珂(Ke WANG),糜燕(Yan MI),张松涛(Songtao ZHANG),陶婷婷(Tingting TAO),杨坤颖(Kunying YANG) Korea Institute for Humanities and Social Sciences 2023 Journal of Global Arts Studies (JGAS) Vol.1 No.1

【背景】乡村振兴其目的是为了使乡村产业兴旺、村民富裕,构建乡村数字供应链是实现宏伟目标的重要路径之一。【目的】提出乡村农林产品数字供应链建议,构建稳健可持续的数字供应链,培育乡村产业及优化产业结构,富裕乡村,实现乡村振兴。【方法】通过实地访谈村镇干部、农民、乡村企业掌握了乡村产业链发展与建设的现状及问题、农林产品消费需求,提出了以需求端为核心构建乡村农林产品数字供应链模型及元素,基于层次分析模型,计算出各要素权重,形成主次分析、层级清晰的数字供应链网络结构。【结果】构建了以龙头企业为核心,多主体协同共育,适合乡村经济发展实际的数字供应链网络、建设重点,从建设规划、数字供应链设计,再到需求可视化、种植加工数字化、专合社经营现代化、物流数字化、风险管理数字化建设方案。【结论】实践证明,数字化技术在推动乡村振兴应用价值明显,推动乡村产业转型升级、提高村民生活水平、建设美丽乡村等,实现产业、组织、人才、文化、生态的全面振兴。 [Background] The purpose of rural revitalization is to promote the prosperity of rural industries and the prosperity of villagers. Building a digital supply chain in rural areas is one of the important paths to achieve the grand goal. [Objective]To propose suggestions for the digital supply chain of rural agricultural and forestry products, build a stable and sustainable digital supply chain, cultivate rural industries and optimize industrial structure, enrich rural areas, and achieve rural revitalization.[Method] Through on-site interviews with village and town officials, farmers, and rural enterprises, had grasped the current situation and problems of the development and construction of rural industrial chains, the demand of agricultural and forestry products, with the demand sort out the digital supply chain of rural agricultural and forestry and element,, calculate the weights by Analytic Hierarchy Process model, form a digital supply chain network structure with clear primary and secondary analysis and hierarchy.[Results]We have built a digital supply chain network system with leading enterprises as the core, multi subject collaborative education, and suitable for the actual development of rural economy. We have elaborated on the key points of rural digital supply chain construction, from construction planning and digital supply chain design, to demand visualization, digitalization of planting and processing, modernization of cooperative operation, digitalization of logistics, and digitalization of risk management.[Conclusion]Practice has proven that digital technology has significant application value in promoting rural revitalization, improving the living standards of villagers, and building beautiful rural areas, achieving overall rural prosperity and achieving comprehensive revitalization of industries, organizations, talents, culture, and ecology.