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RISS 인기검색어
- 검색키워드
- 저자 : Yang Zhuqing (검색결과 3 건)
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Yang Zhuqing,Bao Linbin,Song Wanming,Zhao Xianghui,Liang Huan,Yu Mingjin,Qu Mingren 아세아·태평양축산학회 2024 Animal Bioscience Vol.37 No.2
Objective: The aim of this study was to investigate the impact of dietary nicotinic acid (NA) on apparent nutrient digestibility, rumen fermentation, and rumen microbiota in uncastrated Xiangzhong black cattle. Methods: Twenty-one uncastrated Xiangzhong black cattle (385.08±15.20 kg) aged 1.5 years were randomly assigned to the control group (CL, 0 mg/kg NA in concentrate diet), NA1 group (800 mg/kg NA in concentrate diet) and NA2 group (1,200 mg/kg NA in concentrate diet). All animals were fed a 60% concentrate diet and 40% dried rice straw for a 120-day feeding experiment. Results: Supplemental NA not only enhanced the apparent nutrient digestibility of acid detergent fiber (p<0.01), but also elevated the rumen acetate and total volatile fatty acid concentrations (p<0.05). 16S rRNA gene sequencing analysis of rumen microbiota revealed that dietary NA changed the diversity of rumen microbiota (p<0.05) and the abundance of bacterial taxa in the rumen. The relative abundances of eight Erysipelotrichales taxa, five Ruminococcaceae taxa, and five Sphaerochaetales taxa were decreased by dietary NA (p< 0.05). However, the relative abundances of two taxa belonging to Roseburia faecis were increased by supplemental 800 mg/kg NA, and the abundances of seven Prevotella taxa, three Paraprevotellaceae taxa, three Bifidobacteriaceae taxa, and two operational taxonomic units annotated to Fibrobacter succinogenes were increased by 1,200 mg/kg NA in diets. Furthermore, the correlation analysis found significant correlations between the concentrations of volatile fatty acids in the rumen and the abundances of bacterial taxa, especially Prevotella. Conclusion: The results from this study suggest that dietary NA plays an important role in regulating apparent digestibility of acid detergent fiber, acetate, total volatile fatty acid concentrations, and the composition of rumen microbiota.
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Luan Shi,Zhuqing Liu,Wei Yang,Yaojun Li,Xiaodong Liu,Ran Tao 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.10
If a centrifugal impeller is in deep stall, it requires a large amount of additional energy to break free. As such, it is crucial to study the prediction method of impeller stall and establish its relationship with force and torque. This study employs a computational fluid dynamics numerical simulation method to analyze the flow field within the impeller of a centrifugal pump, while monitoring the changes in hydraulic torque of the blades. By examining the impeller’s internal flow field characteristics and external (energy performance) characteristics curves under different working conditions, the stall process was classified into three stages: germination, transition and stabilization. The evolution of stall cells under different stall stages was also analyzed. We utilized time-frequency conversion and analysis to extract characteristic parameters from instantaneous hydraulic torque results generated under different working conditions. A more effective model for predicting impeller stall stages was built by virtue of support vector machine algorithm. The proposed model exhibits improved feasibility and effectiveness in comparison to traditional prediction methods. It is expected to have significant implications for stable operation monitoring and safety protection of centrifugal pumps.
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Comparison of image masking methods for pump impeller blade region PIV experiments
Xiaodong Liu,Tingting Yan,Qiang Zhong,Zhuqing Liu,Fujun Wang,Yaojun Li,Wei Yang 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.6
Due to the blade reflection effect when applying the PIV technology to the internal flow field measurement of rotating machinery, the blade area requires special treatment. In this paper, zero-value, particle image, random number, and mean-value masking methods are compared and analyzed based on particle images from the PIV challenge and rotating impeller. The peak significance and coordinates deviations are used as the masking effect evaluation criteria. The results indicate that an increase in the interrogation window masking area proportion causes a weakening of the PIV calculation particle cluster displacement peak value. The peak position is shifted, which leads to the wrong velocity vector. The masking area proportion should not be higher than 0.7, 0.5, 0.19, and 0.22 for mean-value, random number, zero-value, and particle image masking methods, respectively. The results show that flow field calculation results near the blade boundary are more accurate for mean-value masking.
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