On Hotelling

Peter Kim.QiLi외2명 한국계량경제학회 1998 JOURNAL OF ECONOMIC THEORY AND ECONOMETRICS Vol.4 No.2

Dynamic Characteristics Identification of an Arch Dam Model via the Phase-Based Video Processing

Qi Li,Gaohui Wang,Aral Sarrafi,Xinqiang Niu,Wenbo Lu,Zhu Mao 대한토목학회 2021 KSCE Journal of Civil Engineering Vol.25 No.1

In recent years, the extraction of structural dynamic characteristics by using phase-based video processing has attracted considerable attention. Edge detection routine is oftentimes employed to obtain the quantified operational deflection shape (ODS) vectors of structures. However, this approach is unreliable because of intensive human supervision and correction. To reduce operational uncertainty, a hybrid computer-vision-based approach called edge detection-region labeling, which involves vision sensor preparation, bottom-hat filtering, edge detection, hole filling, and region labeling, was presented in this work to extract the quantified ODS’s. The performance of this method was firstly evaluated by conducting a lab-scale cantilever beam test and subsequently the phase-based video processing was applied to extract the dynamic characteristics of an arch dam model. The operational modal analysis (OMA) test was conducted on the benchmark dam model. In-plane motions of the dam were captured and processed to identify the natural frequencies of the dam. The structural ODS’s were quantified using the proposed method. A comparison of the modal parameters of the dam identified from the video data with those obtained in the OMA test revealed that the two sets of results were consistent, and the video processing approach was able to bypass the requirement of human supervision, which facilitates the application of the phase-based video processing for complex structures.

Water Dispersible Graphene Sheets Produced from Unassembled Graphene–Polyaniline Nanohybrids

Qi Li,Denian Li,Lijie Dong,Fan Sun,Jing Huang,Haian Xie,Chuanxi Xiong 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.1

We present an effcient process for producing water dispersible graphene sheets from unassembled graphene–polyaniline nanohybrids. The result of atomic force microscopy reveals that over 80% of thus-prepared graphitic sheets are single layers with typical thickness of approximately 0.8 nm. The proportion of modifying molecules in the product is found to be as low as 3.0 wt.%, as determined by elemental analysis. Along with its fascinating water dispersibility and remarkably high electrical conductivity, such material is anticipated to be very promising for use in graphene-based nanoelectronics and high-performance composites.

OPTIMUM RETIREMENT PROBLEM INTEGRATED WITH THE OPTIMUM CONSUMPTION AND PORTFOLIO

Qi Li,Ji-Hun Yoon 한국전산응용수학회 2021 Journal of Applied and Pure Mathematics Vol.3 No.1

In this paper, we investigate an optimum retirement problem integrated with the optimum consumption and portfolio under an infinite time horizon. Since it exists a dis-utility for an investor who has a fixed labor income before retirement, we investigate the classical Merton’s problem integrated by a retirement choice under negative wealth constraints,by using HJB equation and second order ordinary differential equation,and obtain the optimal retirement time, optimal consumption and portfolio such that the investor can choose to retire when his/her wealth exceeds a threshold level and won’t suffer a utility loss from labor any longer. Some numerical implications of the optimum consumption and portfolio are also illustrated in the end of the paper by comparing two different cases.

八大山人作品体现出孤独感的艺术语言表现研究

QI LI 한국동양예술학회 2019 동양예술 Vol.43 No.-

八大山人,明朝最具代表性的画家之一,在清初画坛占据重要地位,常借作品表达自己的身世之感、家国之恨及抑郁苦闷之情,由于社会现实的冲突和内心的痛苦,使八大的作品形成了与别人不同的风格,八大常利用纯熟的技法,将传统哲学融入绘画中,用夸张的技法表达自己对于人生、命运乃至宇宙的思考,成为清初画坛众多“遗民画家”中的佼佼者。 当我们欣赏八大作品时总是会感到孤独,原因是因为他的绘画中有一种孤独的精神,这种精神表现在其绘画中即是不与命运低头的傲骨,体味孤独的淡然乐趣,对生命尊严的探索及对人生价值的感悟,可以说,他将孤独由个人的体验上升到了对于人类命运的思考上。 八大山人艺术中体现的孤独精神与禅宗有关,八大身为明朝皇族,刚刚成年就面临国破家亡,无奈之中遁迹佛门,依佛门长达三十多年之久,即便晚年离开佛门,但心依旧念佛,他的孤独精神深深的打下了禅家的印记,令他终身抒写。八大山人身为明朝后裔,又身居两朝转换之时,特殊的身份及动荡不安的社会背景也必然对八大山人的孤独情感产生客观的影响。多年的颠沛流离,改名换姓,隐逸佛堂,癫痫发病,流浪街头,尤其是晚年生活贫困致极,只靠友人救济维持生活,他的画作中所体现的孤独感,直击人心,他常以自我嘲讽的姿态来对待人生,对待生活,寻求自我的解脱,他的孤独不是刻板,不是无味,而是其与孤独相处体会的只属于自己的真实孤独精神观,所体现的孤独精神,具有睿智的智慧,是中国传统艺术中最为闪耀的发光点之一。 本文共分为四章,第一章简单论述八大山人的一生,引出其绘画中的孤独。第二章说明孤独定义,通过史料和文字中的记载,从中国文化方面剖析孤独内涵。第三章通过画论中的观点及中国传统哲学方面论述八大孤独绘画的思想源泉。第四章通过八大的绘画作品,细致描绘其作品中的孤独精神。希望通过对八大山人的研究,为当代艺术家的创作给予焕然一新的创作思路。

八大山人之孤独感和“托物言志,隐喻抒情”的比兴观研究

QI LI 한국동양예술학회 2019 동양예술 Vol.44 No.-

“托物言志”的比兴观,是中国传统绘画中重要美学思想,是画家在生活中积累的情感以隐喻、象征的表现手法,通过花、草、鱼、虫、鸟、兽等题材的艺术语言形式描绘与表达,寄托自身内心深处的感情、抱负、志向、意趣等。这种传统的表达方式诠释了中国传统文人内敛的本性,是物与心相统一的产物,它与“直抒胸臆”的直接表达方式完全不同,间接婉转的表达自身的情感。 八大山人是中国美术史上重要的代表性人物,其一生悲惨坎坷,“孤独”一词伴随了其一生,成为分析其绘画作品不可避免的关键词。八大最具代表性的即是善用各种拟人比兴的手法来隐喻自身人生经历,表达他对于生活的感悟及人生情感体验等内涵。他的绘画风格单纯缺不失意趣,常常让欣赏者感同身受,产生共鸣。在其作品中,无论是其作品中抽象怪诞的物象,内含无尽讽刺的题画诗,还是物象暗喻的真实内涵,都是八大自身无尽的孤独情感在作品中的映射。 本文共分三部分,第一部分阐述比兴的溯源及发展,第二部分说明比兴如何由最初的诗歌运用转到绘画运用,第三部分通过八大山人的作品进行系统分析,通过物象,题画诗详细分析八大山人作品比兴观所体现出的孤独感。希望通过本文,能够使欣赏者从另一个角度出发,更加了解八大这位伟大的艺术家。

Structural evolution of the thermal conversion products of modified coal tar pitch

Qi Li,Dongyun Han,Haiyan Qiao,Weiwei Shi,Yuqi Zhang,Zubin Cao 한국탄소학회 2023 Carbon Letters Vol.33 No.1

Coal tar pitch is a product with high carbon content and aromatic compounds. Modified coal tar pitch is a high quality raw material for the preparation of intermediate phase pitch, needle coke, carbon microspheres, et al. In this paper, modified coal tar pitch was used as raw material, nitrogen was used as protective gas, and thermal conversion was carried out at constant temperatures (370, 390, 410, 420 °C). Polarized light microscopy, SEM, elemental analysis, FTIR spectroscopy, Raman spectroscopy and XRD diffraction combined with split-peak fitting were used to characterize the microstructures of the thermal transformation products. The results showed that the Iar and CH3/ CH2 contents of the products increased with the gradual increase of the thermal conversion temperature, and the aromatic content increased. And the higher the temperature at the same heating rate, the more the ideal graphite microcrystal content, and the defective graphite microcrystals are converted into ideal graphite microcrystals during the thermal conversion process. When the reaction temperature exceeds 390 °C, the microstructure of the thermal transformation products is anisotropic spheres, and the small spheres fuse with each other and tend to be basin-like and mosaic structure as the temperature increases.

Highly Efficient Biotransformation of Notoginsenoside R1 into Ginsenoside Rg1 by Dictyoglomus thermophilum β-xylosidase Xln-DT

( Qi Li ),( Lei Wang ),( Xianying Fang ),( Linguo Zhao ) 한국미생물생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.4

Notoginsenoside R1 and ginsenoside Rg1 are the main active ingredients of Panax notoginseng, exhibiting anti-fatigue, anti-tumor, anti-inflammatory, and other activities. In a previous study, a GH39 β-xylosidase Xln-DT was responsible for the bioconversion of saponin, a natural active substance with a xylose group, with high selectivity for cleaving the outer xylose moiety of notoginsenoside R1 at the C-6 position, producing ginsenoside Rg1 with potent anti-fatigue activity. The optimal bioconversion temperature, pH, and enzyme dosage were obtained by optimizing the transformation conditions. Under optimal conditions (pH 6.0, 75℃, enzyme dosage 1.0 U/ml), 1.0 g/l of notoginsenoside R1 was converted into 0.86 g/l of ginsenoside Rg1 within 30 min, with a molar conversion rate of approximately 100%. Furthermore, the in vivo anti-fatigue activity of notoginsenoside R1 and ginsenoside Rg1 were compared using a suitable rat model. Compared with the control group, the forced swimming time to exhaustion was prolonged in mice by 17.3% in the Rg1 high group (20 mg/kg·d). Additionally, the levels of hepatic glycogen (69.9-83.3% increase) and muscle glycogen (36.9-93.6% increase) were increased. In the Rg1 group, hemoglobin levels were also distinctly increased by treatment concentrations. Our findings indicate that treatment with ginsenoside Rg1 enhances the anti-fatigue effects. In this study, we reveal a GH39 β-xylosidase displaying excellent hydrolytic activity to produce ginsenoside Rg1 in the pharmaceutical and food industries.

Highly Efficient Biotransformation of Astragaloside IV to Cycloastragenol by Sugar-Stimulated β-Glucosidase and β-Xylosidase from Dictyoglomus thermophilum

( Qi Li ),( Tao Wu ),( Linguo Zhao ),( Jianjun Pei ),( Zhenzhong Wang ),( Wei Xiao ) 한국미생물 · 생명공학회 2019 Journal of microbiology and biotechnology Vol.29 No.12

β-Glucosidases and β-xylosidases are two categories of enzymes that could cleave out nonreducing, terminal β-D-glucosyl and β-D-xylosyl residues with release of D-glucose and Dxylose, respectively. In this paper, two functional β-glucosidase Dth3 and β-xylosidase Xln-DT from Dictyoglomus thermophilum were heterologously expressed in E.coli BL21 (DE3). Dth3 and Xln-DT were relatively stable at 75oC and were tolerant or even stimulated by glucose and xylose. Dth3 was highly tolerant to glucose with a Ki value of approximately 3 M. Meanwhile, it was not affected by xylose in high concentration. The activity of Xln-DT was stimulated 2.13- fold by 1 M glucose and 1.29-fold by 0.3 M xylose, respectively. Furthermore, the β- glucosidase Dth3 and β-xylosidase Xln-DT showed excellent selectivity to cleave the outer C-6 and C-3 sugar moieties of ASI, which established an effective and green method to produce the more pharmacologically active CAG, an exclusive telomerase activator. We measured temperature, pH and dosage of enzyme using a single-factor experiment in ASI biotransformation. After optimization, the optimal reaction conditions were as follows: 75oC, pH 5.5, 1 U of Dth3 and 0.2 U of Xln-DT, respectively. Under the optimized conditions, 1 g/l ASI was transformed into 0.63 g/l CAG with a corresponding molar conversion of 94.5% within 3 h. This is the first report to use the purified thermostable and sugar-tolerant enzymes from Dictyoglomus thermophilum to hydrolyze ASI synergistically, which provides a specific, environment-friendly and cost-effective way to produce CAG.

Adsorption characteristics of methylene blue onto the N-succinyl-chitosan-gpolyacrylamide/ attapulgite composite

Qi Li,Li Wang,Yahong Zhao,Wang Aiqin 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.8

N-succinyl-chitosan-g-polyacrylamide/attapulgite (NSC-g-PAM/APT) composite was applied as adsorbent for the removal of methylene blue (MB) from aqueous solution. The initial pH value of the dye solutions, the contact temperature, the contact time and the concentration of the dye solutions on adsorption capacity of the composite for MB dye were investigated. The adsorption kinetics and isotherms were also studied. It was shown that all the sorption processes were better fitted by pseudo-second-order equation and the Langmuir equation. The results indicated that the adsorption capacity of the composite was higher than those of chitosan (CTS) and attapulgite (APT). The desorption studies revealed that the composite provided the potential for regeneration and reuse after MB dye adsorption, which implied that the composite could be used as quite effective adsorbent for the removal of MB from aqueous solution.