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RISS 인기검색어
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- 저자 : Yonghua Yu (검색결과 4 건)
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A modal approach for the efficient analysis of a bionic multi-layer sound absorption structure
Yonghua Wang,Chengyu Xu,Yanling Wan,Jing Li,Huadong Yu,Luquan Ren 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.2
The interest of this article lies in the proposition of using bionic method to develop a new sound absorber and analyze the efficient of this absorber in a ski cabin. Inspired by the coupling absorption structure of the skin and feather of a typical silent flying bird — owl, a bionic coupling multi-layer structure model is developed, which is composed of a micro-silt plate, porous fibrous material and a flexible micro-perforated membrane backed with airspace. The finite element simulation method with ACTRAN is applied to calculate the acoustic performance of the multi-layer absorber, the vibration modal of the ski cabin and the sound pressure level (SPL) near the skier's ears before and after pasting the absorber at the flour carpet and seats in the cabin. As expected, the SPL near the ears was significantly reduced after adding sound-absorbing material. Among them, the model 2 and model 5 showed the best sound absorption efficiency and the SPL almost reduced 5 dB. Moreover, it was most effctive for the SPL reduction with full admittance configuration at both the carpet and the seats, and the carpet contribution seems to be predominant.
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Study on the Synthesis of Wool-blending Fiber Bundle and New Signs of the Curve
Ren Yonghua,Yu Jianyong The Korean Fiber Society 2005 Fibers and polymers Vol.6 No.4
In this paper, a hand-operating method (tiled test method) of the wool-blending sample is made out, and make use of the method, the test of wool-blending bundle in different blending ratio is accomplished. According to the test data, the synthesis method of the stretch curve is worked out and the synthesis software for the typical stretch curve of wool-blending bundle is designed. Through laboratory hand-operating method, the blending fasciculus applying to fiber bundle test can be obtained in a short time. Calculation for sampling is accomplished in the article. We bring up 9 new signs to describe the characteristics of the curve behind peak for the first time: elongation behind peak (HE), elongation percentage behind peak (HEP), relative elongation rate behind peak (RHE), total break work $(W_a)$, break work behind peak (HW), break work coefficient behind peak (HWC), elongation percentage of half-load behind peak (HEL), load percentage of half-elongation behind peak (HLE), break efficiency behind peak (HEC).
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Baoyue Li,Yonghua Yu,Jia Hu,Bingxin Cao,Yangfeng Yao,Defeng Xu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.12
The vibration signal of rotating mechanical equipment contains a large amount of information that can be used for the fault diagnosis of rotating mechanical equipment. However, the vibration information is distributed in multiple dimensions, and a single-scale analysis cannot effectively reflect its damage characteristics, reducing the accuracy of fault diagnosis. Accordingly, an improved hierarchical fluctuation dispersion entropy (MHFDE) method based on the improved hierarchical processing is proposed. MHFDE can simultaneously mine low- and highfrequency features in the time series, avoiding information omission. Comparison results of the simulated signals show that the proposed method has the advantages of high stability and accurate measurement of complexity. In combination with the multi-cluster feature selection (MCFS) and kernel limit learning machine (KELM) optimized by whale optimization algorithm (WOA), a rotating machinery damage recognition method based on MHFDE-MCFS and WOA-KEM was proposed. Three sets of typical rotating machinery datasets are used to verify the effectiveness of the proposed method. The results show that this method can not only accurately and stably identify the damage types of the three selected machinery but also have a higher accuracy of damage recognition compared with the existing feature extraction methods.
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Qiang Wang,Fengxia Xiao,Fei Qi,Xiaopeng Song,Yonghua Yu 대한암학회 2020 Cancer Research and Treatment Vol.52 No.2
Purpose Fractionated radiotherapy as well as concomitant and adjuvant chemotherapy such as temozolomide for postoperative high-grade glioma (HGG) patients improves progressionfree survival and overall survival. Multiple factors such as chemotherapy, radiotherapy, tumor grade, residual tumor volume, and genetic modifications might play a role in the formation of cognitive impairment. The risk factors of cognitive impairment in postoperative patients with HGG receiving radiotherapy and chemotherapy remains a concern in this population. The purpose of this study was to identify risk factors for cognitive impairment in patients of postoperative HGG. Materials and Methods A total of 229 patients with HGG who underwent surgery were analyzed. Cognitive impairment was defined as a decrease of Cognitive Assessment Montreal (MoCA)’s score in at least two cognitive domains or any MoCA’s score of less than 26 points at the time of study compared with baseline level. Multiple potential risk factors including methylated status of the O6-methylguanine-DNA methyltransferase (MGMT) promoter, glioma World Health Organization (WHO) grade, residual tumor volume, education, and sex were analyzed. Cox univariate and multivariate regression analysis was used to detect the significant risk factors for cognitive impairment. Results At the end of follow-up among the 229 patients, 147 patients (67%) developed cognitive impairment. 82 patients (36%) remained in normal cognitive condition. In multivariate analysis, unmethylated MGMT promoter (hazard ratio [HR], 1.679; 95% confidence interval [CI], 1.212 to 2.326; p=0.002), glioblastoma (HR, 1.550; 95% CI, 1.117 to 2.149; p=0.009), and residual tumor volume > 5.58 cm3 (HR, 1.454; 95% CI, 1.047 to 2.020; p=0.026) were independent risk factors for cognitive impairment. Conclusion Methylated status of the MGMT promoter, glioma WHO grade, and residual tumor volume might be risk factors for the cognitive impairment in postoperative patients with HGG.
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