http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Wavelet-transform-based damping identification of a super-tall building under strong wind loads
An Xu,Jiurong Wu,Ruohong Zhao 한국풍공학회 2014 Wind and Structures, An International Journal (WAS Vol.19 No.4
A new method is proposed in this study for estimating the damping ratio of a super tall building under strong wind loads with short-time measured acceleration signals. This method incorporates two main steps. Firstly, the power spectral density of wind-induced acceleration response is obtained by the wavelet transform, then the dynamic characteristics including the natural frequency and damping ratio for the first vibration mode are estimated by a nonlinear regression analysis on the power spectral density. A numerical simulation illustrated that the damping ratios identified by the wavelet spectrum are superior in precision and stability to those values obtained from Welch’s periodogram spectrum. To verify the efficiency of the proposed method, wind-induced acceleration responses of the Guangzhou West Tower (GZWT) measured in the field during Typhoon Usagi, which affected this building on September 22, 2013, were used. The damping ratios identified varied from 0.38% to 0.61% in direction 1 and from 0.22% to 0.59% in direction 2. This information is expected to be of considerable interest and practical use for engineers and researchers involved in the wind-resistant design of super-tall buildings.
Lu Xu,Chun-Qing Zhao,De-Jin Xu,Guang-Chun Xu,Xiao-Long Xu,Zhao-Jun Han,Ya-Nan Zhang,Zhong-Yan Gu 한국응용곤충학회 2017 Journal of Asia-Pacific Entomology Vol.20 No.2
Nuclear receptors (NRs), which belong to a superfamily of ligand-dependent transcription factors, play essential roles in gene regulation to affect numerous physiological pathways. Twenty NR genes were identified in Nilaparvata lugens by using genomic, transcriptomic and GenBank databases, and categorized into NR0-NR6 subfamilies according to standard nomenclature. Among them, three NR geneswere classed into NR0, four into NR1, eight into NR2, one into NR3, one into NR4, two into NR5, and one into NR6, respectively. A phylogenetic tree of NRs from N. lugens and other representative species was constructed, which provided evolutionary insight into genetic distance. In order to investigate the NRs,whichwere induced by sulfoxaflor, time- and tissue-specific expression profiles of NR genes in fourth-instar nymphs were determined following LD50 sulfoxaflor treatment (0.28 ng/insect) and compared with control samples. NlUSP, NlE78, NlTLL, NlHR51, NlHR83, NlPNR and NlFTZ-F1 were highly expressed following 12–48 h of sulfoxaflor treatment. NlHR39 and NlDSF transcripts were detected in the head and the thorax, respectively. High-level and constitutive expression of NlHR3, NlTLL, NlHR83, NlFTZF1 and NlHR4 were found in the abdomen. Feeding of dsRNAs reduced the expression of NlHR3, NlUSP, NlTLL, NlHR83, NlPNR, NlFTZ-F1 and NlHR4 (35.48–49.77%) and caused significant nymph mortality (69.21–81.45%). These NRs, considered as insecticide targets, may play important function in sulfoxaflor detoxification.
Effects of Reynolds number on the flow field in a low-pressure turbine with incoming wakes
Xu Zhao,Yunfei Wang,Xiaozhong Ma,Yaowen Zhang,Long Yue,Bin Zheng 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.11
In order to further understand the effects of the Reynolds number on the flow field within a low-pressure turbine with incoming wakes, the transition SST turbulence model was employed for numerical simulation under four Reynolds number conditions ranging from 0.6×10 5 to 3.0×10 5 . The numerical results showed that the boundary layer separation at the rear part of the suction surface was prone to occur in the condition of low Reynolds number (Re 2th = 0.6×10 5 ), and the separation bubble was semi-open and semi-closed. The separation bubble impedes the development of the passage vortex and wall vortex towards mid-span region. When the Reynolds number exceeds 1.0×10 5 , boundary layer separation does not occur. The influence of Reynolds number on the total pressure loss coefficient is primarily evident on the suction surface side, and the growth rate of total pressure loss coefficient first increases and then decreases along the streamwise direction. As the Reynolds number increases from 0.6×10 5 to 3.0×10 5 , the peak point location of total pressure loss decreases by approximately 12 %. The influence of Reynolds number on corner vortex and wall vortex is relatively more sensitive compared to that of passage vortex.
Protective effect of Lactobacillus plantarum ATCC8014 on acrylamide-induced oxidative damage in rats
Zhao Sijia,Zhao Xiaoduo,Liu Qingbo,Jiang Yujun,Li Yanhua,Feng Wenxiao,Xu Honghua,Shao Meili 한국응용생명화학회 2020 Applied Biological Chemistry (Appl Biol Chem) Vol.63 No.4
Acrylamide (AA), which is mainly found in fried foods, causes neurotoxicity, genetic toxicity, carcinogenic effects, and DNA damage. This study confirms that a strain of lactic acid bacteria (Lactobacillus plantarum ATCC8014) could alleviate the toxicity of rats by inhibiting the AA-induced oxidative damage. Forty-eight adult male SD rats were randomly divided into eight groups: control group, AA group (40 mg/kg), three different doses (1 × 107 CFU/ml, 1 × 108 CFU/ ml, 1 × 109 CFU/ml of Lactobacillus plantarum ATCC8014) of prevention groups and therapeutic groups, respectively. At the end of three-week experiment, AA treatment produced a significant reduction in the rate of weight gain along with the symptoms of hind limb splay and ataxia. Histological examinations revealed various degrees of injury in five tissues. Levels of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) in group AA rats were significantly decreased, but the level of lipid peroxidation (LPO) was significantly increased (p < 0.05). Both prevention and therapeutic groups with 1 × 109 CFU/ml of Lactobacillus plantarum ATCC8014 could effectively reduce the injury of AA to the body. However, reductions in both groups were not statistically significant.
Xu, Ling,Xu, Hai-Yan,Wang, Feng,Zhang, Feng-Jun,Meng, Ze-Da,Zhao, Wei,Oh, Won-Chun The Korean Ceramic Society 2012 한국세라믹학회지 Vol.49 No.2
Flower-like and plate-like CuO nanopowder has been successfully synthesized using a facile microwave-assisted synthetic route. The morphology and size of the final products strongly depended on microwave power. The phase, structures and morphologies of the as-prepared products were investigated in detail by BET surface area analysis, X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM). In addition, the chemical oxygen demand of polluted lake water was employed for characterization of these new photocatalysts. The results showed correlations between the morphology of CuO micro-crystals and their catalytic properties.
Xu Zhao,Yucheng Su,Hongqiang Wang,Zhiwu Lei,Eming Hu,Fang Hu,Qingliang Wang,Lechang Xu,Shiyao Fan,Xinwei Liu,Xuanzhang Hao 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.1
With the wide application of beryllium globally, industrial wastewater has rapidly increased. Previously, adsorption was effective in treating this issue. However, most adsorbents have a poor removal rate, primarily in the low adsorption capacity. To remove Be from industrial wastewater and overcome the disadvantages of low adsorption capacity and poor removal rate of existing adsorbents, typical agricultural waste lotus leaf was used to prepare Al-activated carbon (Al-AC) by the impregnation-calcination modification of Al(NO3)3. The theoretical maximum adsorption capacity of Al-AC was 32.86 mg/g. Langmuir, Freundlich, and Temkin models were used to thermodynamically analyze Al-AC, and adsorption thermodynamics demonstrated that the adsorption reaction of Al-AC was endothermic. Through characterization analysis, the specific surface area of the modified AC increased from 4.3573 to 155.87 m2/g. This study provides a new approach to preparing and modifying AC and a new method for removing Be from industrial wastewater.
Xu, Tao,Yuan, Rui,Xu, Peng-Cheng,Pan, Dong-Jie,Yang, Woochul,Guo, Hai-Bo,Shen, Yu-Fang,Hu, Jian-Feng,Zhang, Zhi-Jun,Zhao, Jing-Tai Elsevier 2018 Journal of alloys and compounds Vol.762 No.-
<P><B>Abstract</B></P> <P>Uniform, monodisperse yttrium aluminum garnet (YAG) rhombic dodecahedron micro-crystals were synthesized using coprecipitation and hydrothermal methods. The Na<SUB>2</SUB>SO<SUB>4</SUB> as a surfactant was helpful in improving the dispersity of the crystallites and forming well-faceted, micro-sized dodecahedral YAG crystallites. The effect of the reaction time and the solvent has also been studied. The crystal growth mechanism called dissolution/crystallization was determined by analyzing the experimental and simulated results. And the specific well-developed crystal facets in the {110} family have been demonstrated by the theoretical calculation. A higher integrated emission intensity can be achieved for the YAG:Ce crystallites by improving the phase purity, morphology with better developed dodecahedrons, and dispersion. Furthermore, a rather high luminous efficacy (LE = 104.14 lm/W) for the white LED fabricated using the YAG:Ce<SUP>3+</SUP> phosphor prepared in this work was realized. The correlation between the crystal growth, morphology and luminescence properties of YAG crystallites has been established, which exhibits a great importance for the synthesis and application of mono-dispersed YAG crystallites.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Uniform and monodisperse YAG rhombic dodecahedron micro-crystals were synthesized. </LI> <LI> The growth mechanism of YAG rhombic dodecahedron was studied through experimental and computational simulation. </LI> <LI> The correlation between the crystal growth, morphology and luminescence of YAG crystallites was established. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>