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Wavelet-based iterative data enhancement for implementation in purification of modal frequency for extremely noisy ambient vibration tests in Shiraz-Iran

Hassan YOUSEFI, Alireza TAGHAVI KANI, Iradj MAHMOUDZADEH KANI, Soheil MOHAMMADI

《结构与土木工程前沿（英文）》 2020年 第14卷 第2期   页码 446-472 doi: 10.1007/s11709-019-0605-8

摘要： The main purpose of the present study is to enhance high-level noisy data by a wavelet-based iterative filtering algorithm for identification of natural frequencies during ambient wind vibrational tests on a petrochemical process tower. Most of denoising methods fail to filter such noise properly. Both the signal-to-noise ratio and the peak signal-to-noise ratio are small. Multiresolution-based one-step and variational-based filtering methods fail to denoise properly with thresholds obtained by theoretical or empirical method. Due to the fact that it is impossible to completely denoise such high-level noisy data, the enhancing approach is used to improve the data quality, which is the main novelty from the application point of view here. For this iterative method, a simple computational approach is proposed to estimate the dynamic threshold values. Hence, different thresholds can be obtained for different recorded signals in one ambient test. This is in contrast to commonly used approaches recommending one global threshold estimated mainly by an empirical method. After the enhancements, modal frequencies are directly detected by the cross wavelet transform (XWT), the spectral power density and autocorrelation of wavelet coefficients. Estimated frequencies are then compared with those of an undamaged-model, simulated by the finite element method.

关键词： ambient vibration test     high level noise     iterative signal enhancement     wavelet     cross and autocorrelation of wavelets    

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心电图信号的频域分析

涂承媛,曾衍钧,李树信

《中国工程科学》 2002年 第4卷 第12期   页码 66-70

摘要：

提出了一种简便有效的、由心电图（ECG）曲线提取QRS-T复合波的新方法，从而获得P波（当房颤未发生时）或f波（当房颤时）；利用功率谱、自相关、互相关等信号处理技术，对它进行了处理和分析，特别是，比较了未房颤时和发生房颤时的相关信息的显著差别。

关键词： 心电图（ECG）     QRS-T复合波     P波     房颤波（f波）     频数直方图     功率谱     自相关     互相关    

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Methods and applications of DEA cross-efficiency: Review and future perspectives

Jie WU, Jiasen SUN, Liang LIANG

《工程管理前沿（英文）》 2021年 第8卷 第2期   页码 199-211 doi: 10.1007/s42524-020-0133-1

摘要： The field of engineering management usually involves evaluation issues, such as program selection, team performance evaluation, technology selection, and supplier evaluation. The traditional self-evaluation data envelopment analysis (DEA) method usually exaggerates the effects of several inputs or outputs of the evaluated decision-making unit (DMU), resulting in unrealistic results. To address this problem, scholars have proposed the cross-efficiency evaluation (CREE) method. Compared with the DEA method, CREE can rank DMUs more completely by using reasonable weights. With the extensive application of this technique, several problems, such as non-unique weights and non-Pareto optimal results, have arisen in CREE methods. Therefore, the improvement of CREE has attracted the attention of many scholars. This paper reviews the theory and applications of CREE, including the non-uniqueness problem, the aggregation of cross-efficiency data, and applications in engineering management. It also discusses the directions for future research on CREE.

关键词： cross-efficiency evaluation     efficiency     secondary goal model     aggregation     review    

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Prevalence and determinations of physical inactivity among public hospital employees in Shanghai, China: a cross-sectional

null

《医学前沿（英文）》 2015年 第9卷 第1期   页码 100-107 doi: 10.1007/s11684-014-0372-9

摘要：

This study aims to explore the prevalence and determinations of physical inactivity among hospital employees in Shanghai, China. A cross-sectional study of 4612 employees aged 19 to 68 years was conducted through stratified cluster sampling from different classes of Shanghai hospitals in 2011. The total physical activity was evaluated using the metabolic equivalent according to the Global Physical Activity Questionnaire. Among the participants, 38.5%, 32.3%, and 64.6% of the employees are inactive at work, commuting, and taking leisure time, respectively. Up to 41.8% of the men and 37.8% of the women (P = 0.012) are physically inactive. When the age and educational level are adjusted, male doctors and medical technicians show a higher percentage of physical inactivity than male workers in logistics (P = 0.001). Among females, employees who are working in second- and third-class hospitals show a higher proportion of physical inactivity than those who are working in community health care centers. Logistic regression analyses show that the odds ratios (ORs) of leisure-time physical inactivity associated with the intensity of physical activity at work are 2.259, 2.897, and 4.266 for men (P<0.001) and 2.456, 3.259, and 3.587 for women (P<0.001), respectively. The time during commuting activities is significantly associated with leisure-time physical inactivity in either sex (OR= 2.116 for men and 2.173 for women, P<0.001). Hospital employees, particularly doctors and medical technicians, show a higher proportion of physical inactivity than other inhabitants in Shanghai. The time and intensity of activity at work and commuting are associated with leisure-time activities.

关键词： prevalence     determination     employee     public hospital     cross-sectional study     physical inactivity    

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River Chief System (RCS): An experiment on cross-sectoral coordination of watershed governance

Longfei Wang, Jiaxin Tong, Yi Li

《环境科学与工程前沿（英文）》 2019年 第13卷 第4期 doi: 10.1007/s11783-019-1157-9

摘要：

The trans-regional characteristics of watershed governance produce more problems beyond the capacity of each individual water-related department, leading to the fragmentation of watershed management. The River Chief System (RCS) has experienced swift developments over the past decade in China by appointing the local government heads as river chiefs. RCS works efficiently in the short-term due to its superiority in the inclusion of clear responsibility, authority, and multi-sectoral collaboration. However, the characteristics of the authority-based vertical coordination of the hierarchical system remain unchanged, and therefore the problems of organizational logic and the responsibility dilemma still exist. Tasks including perfecting of laws, integrated watershed management, and public participation still need to be completed. RCS reflects the routine and characteristics of the migration of national governance, and as such provides new insights for other developing countries in the design of river management systems.

关键词： River Chief System     Watershed governance     Cross-sectoral coordination     Environmental protection    

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Air bearing center cross gap of neutron stress spectrometer sample table support system

Yang LI,Yunxin WU,Hai GONG,Xiaolei FENG

《机械工程前沿（英文）》 2016年 第11卷 第4期   页码 403-411 doi: 10.1007/s11465-016-0405-y

摘要：

A support system is the main load-bearing component of sample table for neutron stress spectrometer, and air bearing is an important element of a support system. The neutron stress spectrometer sample table was introduced, and the scheme for air bearing combination was selected. To study the performance of air bearing center cross gap, finite element models (FEMs) were established based on air motion and Reynolds equations, effects of air supply pressure, and gap parameters on the overturning moment and bearing capacity of air bearing center cross gap were analyzed. Results indicate that the width, depth, and height differences of the marble floor gap played important roles in the performance of the air bearing. When gap width is lesser than 1 mm and gap depth is lower than 0.4 mm, bearing capacity and overturning moment would vary rapidly with the variation of the width and depth. A gap height difference results in the bearing capacity dropping rapidly. The FEM results agree well with experimental results. Further, findings of the study could guide the design of the support system and marble floor.

关键词： neutron stress spectrometer     sample table     support system     air bearing     center cross gap     simulation     experiment    

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RESPONSE OF WHEAT COMPOSITE CROSS POPULATIONS TO DISEASE AND CLIMATE VARIATION OVER 13 GENERATIONS

《农业科学与工程前沿（英文）》 2021年 第8卷 第3期   页码 400-415 doi: 10.15302/J-FASE-2021394

摘要：

Since the F5 (2005), three winter wheat composite cross populations (CCPs) based on germplasm specifically suitable for low-input conditions were subjected to natural selection under organic and conventional management. In the F6, each CCP was divided into two parallel populations (12 CCPs in total) and maintained continuously until 2018. Commonly used modern cultivars with different disease susceptibilities were grown alongside to assess the agronomic performance of the CCPs. The organically managed CCPs were comparable in yield and foliar disease resistance to two continuously used reference cultivars, Achat and Capo. In contrast, under conventional management the cv. Capo outyielded the CCPs (Achat was not tested), highlighting the importance of parental cultivar choice for specific management systems. The CCPs were found to be moderately resistant to brown rust and even to the newly emerged stripe rust races prevalent in Europe since 2011. Differences between the CCPs were mainly due to parental genetic background and were significant in the first five generations, but were no longer so in the last five generations. In addition, these differences tended to vary depending on the experimental year and the environmental stresses present. In conclusion, the CCPs despite being derived from older cultivars are able to compete with more recently released reference cultivars under organic farming practices and represent a dynamic germplasm resource.

 

关键词： evolutionary breeding     heterogeneous crop population     management system    

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Technical innovation for Sanyang Road Cross-river Tunnel Project

Yu ZHONG

《工程管理前沿（英文）》 2018年 第5卷 第3期   页码 411-415 doi: 10.15302/J-FEM-2018206

摘要：

关键词： valign=     top     class=     J_zhaiyao    

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Mechanics analysis of thin-walled box continuous girder with variable cross-sections in considering effect

Yuji CHEN, Qizhi LUO,

《结构与土木工程前沿（英文）》 2009年 第3卷 第4期   页码 352-356 doi: 10.1007/s11709-009-0057-7

摘要： In order to study the mechanics behavior of a thin-walled box continuous girder with variable cross-sections, using potential variation theories, considering the effect of shear lag of flange’s stress and the nonlinear geometry of vertical displacement, and evolving five generalized displacements with the spline function, the large deflection problem of the thin-walled box continuous girder with variable cross-section was transformed to a nonlinear algebraic equation, which was solved using the Newton-Raphon iterative method. The results of the calculation show that different shear lag warp functions to the cantilever, top and bottom plate should be taken to analyze the mechanics behavior of the thin-walled box continuous girder reliably. The thin-walled box continuous girder with variable cross-sections has more reasonable stress state and is more adaptable for the longitudinal change of internal forces than that with equal cross-sections. The effect of large deflection on the stress and displacement of the thin-walled box continuous girder with variable cross-sections depends on the values of the load.

关键词： thin-walled box girder with variable cross-sections     potential variational theory     shear lag     large deflection problem    

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Experimental study on the temperature dependence of ultraviolet absorption cross-sections of sulfur dioxide

ZHANG Shiliang, ZHOU Jie, CHEN Xiaohu

《能源前沿（英文）》 2008年 第2卷 第2期   页码 183-186 doi: 10.1007/s11708-008-0025-2

摘要： The photoabsorption cross-sections of sulfur dioxide were measured in the spectral regions of 200–230 nm and 275–315 nm at 298–415 K, using a grating monochromator with a resolution of 0.2 nm. The discrete absorption cross-section is directly correlated with the number of quantum excited from the base state. The absorption cross-sections at the peaks of discrete bands decreased linearly with the increase of temperature, which corresponded to the decrease in the population of vibrational and rotational transitions from the base level to higher excitation levels. The absorption cross-section peaks decreased linearly when the temperature increased from 298 to 415 K, with relative drops of 74.0% and 75.8% at 200–230 nm and 275–315 nm, respectively. Another distinctive feature of sulfur dioxide absorption spectra in the above two spectral regions was the quasiperiodic structure of the absorption peaks, whose equal wavelength intervals were 1.53 nm and 1.95 nm, respectively. Red and blue shifts were not found at the absorption peak positions.
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Mild and highly regioselective synthesis of biaryl acids via Rh(I)-catalyzed cross-dehydrogenative coupling

Yun Liu, Youquan Zhu, Chaojun Li

《化学科学与工程前沿（英文）》 2018年 第12卷 第1期   页码 3-8 doi: 10.1007/s11705-017-1693-4

摘要： A mild and efficient synthesis for the biaryl acids via rhodium-catalyzed cross-dehydrogenative coupling reaction has been developed. This novel protocol with sodium chlorite as an oxidant featured many advantages such as mild reaction conditions, high regioselectivity, tolerance of various functional groups, and good to excellent yields.

关键词： biaryl acids     cross-dehydrogenative coupling     rhodium-catalyzed    

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Synthesis of micro/meso porous carbon for ultrahigh hydrogen adsorption using cross-linked polyaspartic

Jun Wei, Jianbo Zhao, Di Cai, Wenqiang Ren, Hui Cao, Tianwei Tan

《化学科学与工程前沿（英文）》 2020年 第14卷 第5期   页码 857-867 doi: 10.1007/s11705-019-1880-6

摘要： In addition to the specific surface area, surface topography and characteristics such as the pore size, pore size distribution, and micro/mesopores ratio are factors that determine the performance of porous carbons (PCs) in the fields of energy, catalysis, and adsorption. Based on the mechanism of weight loss of polyaspartic acid at high temperatures, this study provided a new method for adjusting the surface morphology of PCs by changing the cross-linking ratio of the precursor, where cross-linked polyaspartic acid was used as precursor without additional activating agents. N adsorption analysis indicated that the specific surface area of the obtained PCs was as high as 1458 m ·g , of which 1200 m ·g was the contribution of the microporous area and the highest pore volume was 1.13 cm ·g , of which the micropore volume was 0.636 cm ·g . The thermogravimetric analysis results of the precursor, and also the scanning electron microscopy and Brunauer–Emmet–Teller analysis results of the carbonization product confirmed that the prepared PCs presented multilevel pore structure, and the diameters of most pores were 0.78 and 3.97 nm; moreover, the pore size distribution was relatively uniform. This conferred the PCs the ultrahigh hydrogen adsorption capacity of up to 4.52 wt-% at 77 K and 1.13 bar, in addition to their great energy storage and catalytic potential.

关键词： porous carbon     multilevel pores     polyaspartic acid     cross-linking     hydrogen adsorption    

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functionalized cellulose based Pd nanoparticles: An efficient and ecofriendly catalyst for the Suzuki cross-coupling

Peibo Hu,Yahao Dong,Xiaotian Wu,Yuping Wei

《化学科学与工程前沿（英文）》 2016年 第10卷 第3期   页码 389-395 doi: 10.1007/s11705-016-1575-1

摘要： A palladium catalyst supported on 2-aminopyridine functionalized cellulose was synthesized and fully characterized by inductively coupled plasma atomic emission spectroscopy, transmission electron microscope, Fourier transform infrared spectroscopy, thermogravimetric analysis and X-ray photoelectron spectrometry. This catalyst can be applied in the Suzuki cross-coupling reaction of aryl halides with arylboronic acids in 50% ethanol to afford biaryls in?good yields, and easily recycled by simple filtration after reaction without the loss of metal Pd.

关键词： cellulose-supported     2-aminopyridine     palladium nanoparticles     ecofriendly catalyst     Suzuki cross-coupling reaction    

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Nonpolar cross-stacked super-aligned carbon nanotube membrane for efficient wastewater treatment

《环境科学与工程前沿（英文）》 2023年 第17卷 第3期 doi: 10.1007/s11783-023-1630-3

摘要：

● A novel nonpolar super-aligned carbon nanotube (SACNT) membrane was prepared.

关键词： Membrane fouling     Wastewater     Membrane separation     Antifouling     Aligned carbon nanotube    

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小波尺度谱在AE信号特征提取中的应用

肖思文,廖传军,李学军

《中国工程科学》 2008年 第10卷 第11期   页码 69-75

摘要：

通过分析典型声发射信号及其特征提取，将小波尺度谱引入到声发射故障诊断领域，首次提出了声发射信号的小波尺度谱分析法。给出了小波基函数及其参数的选取，克服了声发射信号小波尺度谱的时、频分辨率不能同时达到最好的缺陷。将小波尺度谱用于声发射检测的滚动轴承损伤类型及部件的识别，诊断结果十分直观、清晰、准确。仿真分析和实验研究均表明小波尺度谱能有效应用于基于声发射技术的状态监测与故障诊断。

关键词： 小波尺度谱     声发射     特征提取     故障诊断     滚动轴承    

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标题 作者 时间 类型 操作

Wavelet-based iterative data enhancement for implementation in purification of modal frequency for extremely noisy ambient vibration tests in Shiraz-Iran

Hassan YOUSEFI, Alireza TAGHAVI KANI, Iradj MAHMOUDZADEH KANI, Soheil MOHAMMADI

期刊论文

心电图信号的频域分析

涂承媛,曾衍钧,李树信

期刊论文

Methods and applications of DEA cross-efficiency: Review and future perspectives

Jie WU, Jiasen SUN, Liang LIANG

期刊论文

Prevalence and determinations of physical inactivity among public hospital employees in Shanghai, China: a cross-sectional

null

期刊论文

River Chief System (RCS): An experiment on cross-sectoral coordination of watershed governance

Longfei Wang, Jiaxin Tong, Yi Li

期刊论文

Air bearing center cross gap of neutron stress spectrometer sample table support system

Yang LI,Yunxin WU,Hai GONG,Xiaolei FENG

期刊论文

RESPONSE OF WHEAT COMPOSITE CROSS POPULATIONS TO DISEASE AND CLIMATE VARIATION OVER 13 GENERATIONS

期刊论文

Technical innovation for Sanyang Road Cross-river Tunnel Project

Yu ZHONG

期刊论文

Mechanics analysis of thin-walled box continuous girder with variable cross-sections in considering effect

Yuji CHEN, Qizhi LUO,

期刊论文

Experimental study on the temperature dependence of ultraviolet absorption cross-sections of sulfur dioxide

ZHANG Shiliang, ZHOU Jie, CHEN Xiaohu

期刊论文

Mild and highly regioselective synthesis of biaryl acids via Rh(I)-catalyzed cross-dehydrogenative coupling

Yun Liu, Youquan Zhu, Chaojun Li

期刊论文

Synthesis of micro/meso porous carbon for ultrahigh hydrogen adsorption using cross-linked polyaspartic

Jun Wei, Jianbo Zhao, Di Cai, Wenqiang Ren, Hui Cao, Tianwei Tan

期刊论文

functionalized cellulose based Pd nanoparticles: An efficient and ecofriendly catalyst for the Suzuki cross-coupling

Peibo Hu,Yahao Dong,Xiaotian Wu,Yuping Wei

期刊论文

Nonpolar cross-stacked super-aligned carbon nanotube membrane for efficient wastewater treatment

期刊论文

小波尺度谱在AE信号特征提取中的应用

肖思文,廖传军,李学军

期刊论文