Energy factor of high-strength-steel frames with energy dissipation bays under repeated near-field earthquakes

Ke Ke,Michael C.H. Yam,Xu-Hong Zhou,Fuming Wang,Fei Xu 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.3

This investigation contributes to quantification of the inelastic seismic demands for high strength steel moment resisting frames equipped with energy dissipation bays (HSSF-EDBs) subjected to seismic sequences composed of repeated near-field ground motions. The emphasis is placed on the energy factor demand. A statistical examination of a database with more than eighty million energy factor demands of single-degree-of-freedom (SDOF) oscillators representing HSSF-EDBs responding in different yielding stages is conducted. The research findings show that in the damage-control stage, the energy factor which quantifies the peak seismic demand of a HSSF-EDB structure is insensitive to the repeated near-field earthquake motions. In contrast, a remarkable elevation of the energy factor is observed when oscillators characterising HSSF-EDBs progress into the ultimate stage. In addition, an increasing post-yielding stiffness ratio of the nonlinear force-displacement response in the damage-control stage may produce a detrimental effect on HSSF-EDBs progressing into the ultimate stage under repeated near-field earthquakes due to the corresponding evident increase of seismic demands. A nonlinear regression model quantifying the mean energy factor demand of the system under repeated near-field earthquake motions is proposed to facilitate performance-based seismic design of HSSF-EDBs.

Stimulation of Oligonucleotide-Directed Gene Correction by Red Expression and MSH2 Depletion in Human HT1080 Cells

Ke Xu,A. Francis Stewart,Andrew C.G. Porter 한국분자세포생물학회 2015 Molecules and cells Vol.38 No.1

The correction of disease-causing mutations by singlestrand oligonucleotide-templated DNA repair (ssOR) is an attractive approach to gene therapy, but major improvements in ssOR efficiency and consistency are needed. The mechanism of ssOR is poorly understood but may involve annealing of oligonucleotides to transiently exposed single- stranded regions in the target duplex. In bacteria and yeast it has been shown that ssOR is promoted by expression of Red, a single-strand DNA annealing protein from bacteriophage lambda. Here we show that Red expression is well tolerated in a human cell line where it consistently promotes ssOR. By use of short interfering RNA, we also show that ssOR is stimulated by the transient depletion of the endogenous DNA mismatch repair protein MSH2. Furthermore, we find that the effects of Red expression and MSH2 depletion on ssOR can be combined with a degree of cooperativity. These results suggest that oligonucleotide annealing and mismatch recognition are distinct but interdependent events in ssOR that can be usefully modulated in gene correction strategies.

A High-Robust Grid-Side Current Feedback Active Damping Design Method for Gridconnected Inverter

Ke Xu,Li Peng,Weibiao Wu,Bowei Lin,Shirong Yang 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

Grid-connected inverter with LCL filter is widely employed in renewable energy generation system due to high harmonic suppression ability. However, the resonance issue caused by LCL filter is brought easily. To solve this issue, grid-side current feedback active damping control strategy based on proportional derivative algorithm is employed for cost consideration. Taking digital control delay time into consideration, the active damping method is analyzed in discrete domain. A parameter design method based on dominant pole optimization is proposed, which can not only enhance damping ability but also achieve high robust performance. The validity of the proposed method is finally confirmed by the experimental results.

Synthesis and Characterization of pH and Temperature Sensitive Hydrogel Based on Poly(N-isopropylacrylamide), Poly(ε-caprolactone), Methylacrylic Acid, and Methoxyl Poly(ethylene glycol)

Xu Xu,Jia Song,Ke Wang,YingChun Gu,Feng Luo,XiaoHai Tang,Ping Xie,ZhiYong Qian 한국고분자학회 2013 Macromolecular Research Vol.21 No.8

In this paper, a novel biodegradable and pH/thermo-sensitive hydrogel based on poly(ε-caprolactone),methoxyl poly(ethylene glycol), methylacrylic acid and N-isopropylacrylamide was prepared by UV-initiated free radical polymerization. The hydrogels were characterized by Fourier transforms infrared ray. The thermal responsibility was investigated with the help of differential scanning calorimetry. Swelling behavior in aqueous medium with different pH value was studied in detail. When the pH value of the aqueous medium was increased from 1.2 to 7.2,the swelling ratio of the hydrogels increased accordingly. The morphology was observed by scanning electron microscopy, and the hydrolytic degradation behavior in different aqueous media (pH 1.2 and pH 7.2) was also investigated in detail. The prepared biodegradable pH/thermo-sensitive hydrogel based on poly(ε-caprolactone), methoxyl poly(ethylene glycol), methylacrylic acid and N-isopropylacrylamide hold great promise in the development of a smart drug delivery system.

Signal processing method based on energy ratio for detecting leakage of SG using EVFM

Xu Wei,Xu Ke-Jun,Yan Xiao-Xue,Yu Xin-Long,Wu Jian-Ping,Xiong Wei 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.8

In the sodium-cooled fast reactor, the steam generator is a heat exchange device between sodium and water, which may cause leakage, resulting in a sodium-water reaction accident, which in turn affects the safe operation of the entire nuclear reactor. To this end, the electromagnetic vortex flowmeter is used to detect leakage of the steam generator and its signal processing method is studied in this paper. The hydraulic experiment was carried out by using water instead of liquid sodium, and the sensor output signal of the electromagnetic vortex flowmeter under different gas injection volumes was collected. The bubble noise signal is reflected by the base line of the sensor output signal. According to the relationship between the proportion of the bubble noise signal in the sensor output signal and the gas injection volume, a signal processing method based on the energy ratio calculation is proposed to detect whether the water contains bubbles. The gas injection experiment of liquid sodium was conducted to verify the effectiveness of the signal processing method in the detection of bubbles in sodium, and the minimum detectable leak rate of water in the steam generator was detected to be 0.2 g/s.

Signal processing method of bubble detection in sodium flow based on inverse Fourier transform to calculate energy ratio

Xu, Wei,Xu, Ke-Jun,Yu, Xin-Long,Huang, Ya,Wu, Wen-Kai Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.9

Electromagnetic vortex flowmeter is a new type of instrument for detecting leakage of steam generator, and the signal processing method based on the envelope to calculate energy ratio can effectively detect bubbles in sodium flow. The signal processing method is not affected by changes in the amplitude of the sensor output signal, which is caused by changes in magnetic field strength and other factors. However, the detection sensitivity of the electromagnetic vortex flowmeter is reduced. To this end, a signal processing method based on inverse Fourier transform to calculate energy ratio is proposed. According to the difference between the frequency band of the bubble noise signal and the flow signal, only the amplitude in the frequency band of the flow signal is retained in the frequency domain, and then the flow signal is obtained by the inverse Fourier transform method, thereby calculating the energy ratio. Using this method to process the experimental data, the results show that it can detect 0.1 g/s leak rate of water in the steam generator, and its performance is significantly better than that of the signal processing method based on the envelope to calculate energy ratio.

Cutting force and machine kinematics constrained cutter location planning for five-axis flank milling of ruled surfaces

Ke Xu,Jiarui Wang,Chih-Hsing Chu,Kai Tang 한국CDE학회 2017 Journal of computational design and engineering Vol.4 No.3

Five-axis flank milling has been commonly used in the manufacturing of complex workpieces because of its greater productivity than that of three-axis or five-axis end milling. The advantage of this milling operation largely depends on effective cutter location planning. The finished surface sometimes suffers from large geometrical errors induced by improper tool positioning, due to the non-developability of most ruled surfaces in industrial applications. In addition, a slender flank-milling cutter may be deflected when subjected to large cutting forces during the machining process, further degrading the surface quality or even breaking the cutter. This paper proposes a novel tool path planning scheme to address those problems. A simple but effective algorithm is developed to adaptively allocate a series of cutter locations over the design surface with each one being confined within an angular rotation range. The allocation result satisfies a given constraint of geometrical errors on the finished surface, which consists of the tool positioning errors at each cutter location and the sweeping errors between consecutive ones. In addition, a feed rate scheduling algorithm is proposed to maximize the machining efficiency subject to the cutting force constraint and the kinematical constraints of a specific machine configuration. Simulation and experimental tests are conducted to validate the effectiveness of the proposed algorithms. Both the machining efficiency and finish surface quality are greatly improved compared with conventional cutter locations.

Probability Weighting Effect in Vertex Cover of Networks Via Prospect-Theoretic Learning

Xu, Ke,Wu, Ke,Zhou, Rongpei 한국통신학회 2023 Journal of communications and networks Vol.25 No.2

Game-theoretic learning methods for the vertexcover problem have been investigated in this paper. In thetraditional game theory, the establishment of the game modelis based on the complete objectivity of the players, and theexisting game models describe the vertex cover problem mainlyalong this path. In contrast, this paper considers the impactof players’ subjectivity on decision-making results. First, wepresent a covering game model, where the utility function ofthe player is established under the prospect theory. Then, bypresenting a rounding function, the states of all vertices underNash equilibrium satisfies vertex cover state of a general network. After then, we present a fictitious play distributed algorithm,which can guarantee that the states of all vertices converge aNash equilibrium. Finally, the simulation results are presentedto assess the impact of players’ subjectivity on the overall coverresults of networks.

Enhanced Visible-Light Driven Photocatalytic Performances Over LaFeO3/NiO Modified Porous g-C3N4 Nanosheets

Ke Xu,Xiaosheng Yang,Dagao Sun,Xin Yang,Yumei Zhou,Wei Li,Qindan Yang,Xianjiong Yang,Rong Li,Jian Feng 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2020 NANO Vol.15 No.02

LaFeO3/NiO modified g-C3N4 nanosheets (L-N/CNS) were synthesized by a two-step method. HRTEM results showed that an intimate contact between LaFeO3, NiO and N-CNS was successfully established. Ninety percent of phenol was degraded within 120 min, and the hydrogen evolution rate of 171.2 μmol h -1 g -1 was obtained over the L-N/CNS heterojunctions under the visible-light irradiation. It was higher than that of g-C3N4 nanosheets, NiO modified g-C3N4 and LaFeO3/g-C3N4. The ·O2 - radicals acted the crucial role in the photocatalytic degradation reaction. EIS, PL and time-resolved fluorescence spectra demonstrated that L-N/CNS possessed the highest charge separation efficiency. The intimate contact between LaFeO3, NiO and g-C3N4 nanosheets promoted the separation and transfer of photo-induced electron–hole pairs and consequently prolonged the exciton lifetime, and implied more photo-induced electrons could be probably involved in the photocatalytic reactions on the surface of photocatalysts. Thus, the visible-light driven photocatalytic performances of L-N/CNS were effective. This work provided a feasible method to design and construct heterostructures for the exploitation of solar energy.

Six new dammarane-type triterpene saponins from Panax ginseng flower buds and their cytotoxicity

Ke-Ke Li,Sha-Sha Li,Fei Xu,Xiao-Jie Gong 고려인삼학회 2020 Journal of Ginseng Research Vol.44 No.2

Background: Panax ginseng has been used for a variety of medical purposes in eastern countries formore than two thousand years. From the extensive experiences accumulated in its long medication usehistory and the substantial strong evidence in modern research studies, we know that ginseng hasvarious pharmacological activities, such as antitumor, antidiabetic, antioxidant, and cardiovascularsystemeprotective effects. The active chemical constituents of ginseng, ginsenosides, are rich instructural diversity and exhibit a wide range of biological activities. Methods: Ginsenoside constituents from P. ginseng flower buds were isolated and purified by variouschromatographic methods, and their structures were identified by spectroscopic analysis and comparisonwith the reported data. The 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H- tetrazolium bromidemethod was used to test their cytotoxic effects on three human cancer cell lines. Results: Six ginsenosides, namely 6’emalonyl formyl ginsenoside F1 (1), 3beacetoxyl ginsenoside F1 (2),ginsenoside Rh24 (6), ginsenoside Rh25 (7), 7behydroxyl ginsenoside Rd (8) and ginsenoside Rh26 (10)were isolated and elucidated as new compounds, together with four known compounds (3e5 and 9). Inaddition, the cytotoxicity of these isolated compounds was shown as half inhibitory concentration values,a tentative structureeactivity relationship was also discussed based on the results of our bioassay. Conclusion: The study of chemical constituents was useful for the quality control of P. ginseng flowerbuds. The study on antitumor activities showed that new Compound 1 exhibited moderate cytotoxicactivities against HL-60, MGC80-3 and Hep-G2 with half inhibitory concentration values of 16.74, 29.51and 20.48 mM, respectively.