期刊文献+
共找到5,074篇文章
< 1 2 250 >
每页显示 20 50 100
A Bayesian multi-model inference methodology for imprecise momentindependent global sensitivity analysis of rock structures
1
作者 Akshay Kumar Gaurav Tiwari 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第3期840-859,共20页
Traditional global sensitivity analysis(GSA)neglects the epistemic uncertainties associated with the probabilistic characteristics(i.e.type of distribution type and its parameters)of input rock properties emanating du... Traditional global sensitivity analysis(GSA)neglects the epistemic uncertainties associated with the probabilistic characteristics(i.e.type of distribution type and its parameters)of input rock properties emanating due to the small size of datasets while mapping the relative importance of properties to the model response.This paper proposes an augmented Bayesian multi-model inference(BMMI)coupled with GSA methodology(BMMI-GSA)to address this issue by estimating the imprecision in the momentindependent sensitivity indices of rock structures arising from the small size of input data.The methodology employs BMMI to quantify the epistemic uncertainties associated with model type and parameters of input properties.The estimated uncertainties are propagated in estimating imprecision in moment-independent Borgonovo’s indices by employing a reweighting approach on candidate probabilistic models.The proposed methodology is showcased for a rock slope prone to stress-controlled failure in the Himalayan region of India.The proposed methodology was superior to the conventional GSA(neglects all epistemic uncertainties)and Bayesian coupled GSA(B-GSA)(neglects model uncertainty)due to its capability to incorporate the uncertainties in both model type and parameters of properties.Imprecise Borgonovo’s indices estimated via proposed methodology provide the confidence intervals of the sensitivity indices instead of their fixed-point estimates,which makes the user more informed in the data collection efforts.Analyses performed with the varying sample sizes suggested that the uncertainties in sensitivity indices reduce significantly with the increasing sample sizes.The accurate importance ranking of properties was only possible via samples of large sizes.Further,the impact of the prior knowledge in terms of prior ranges and distributions was significant;hence,any related assumption should be made carefully. 展开更多
关键词 Bayesian inference Multi-model inference statistical uncertainty Global sensitivity analysis(GsA) Borgonovo’s indices Limited data
下载PDF
Transitivity Analysis of the Energy in China’s New Era
2
作者 SHAN Ting WANG Yu 《Journal of Literature and Art Studies》 2024年第2期170-176,共7页
At present,with the steady development of the global economy,more and more countries begin to pay attention to the impact of ecological environment on economic development and human society,so the ecological environme... At present,with the steady development of the global economy,more and more countries begin to pay attention to the impact of ecological environment on economic development and human society,so the ecological environment has become a global issue that cannot be ignored in today’s era.Therefore,from the perspective of the ecological philosophy of Diversity&Harmony as well as Interaction&Co-existence,this paper will conduct ecological discourse analysis on the Energy in China’s New Era based on the transitivity system of systemic-functional grammar,and use the Corpus analysis software UAM Corpus Tool 3.3x to label and make statistics on the transitivity system,aiming to explore the distribution characteristics of the transitivity system in this white paper.Through the transitivity analysis of the white paper,this study helps readers to have a deeper understanding of the positive significance contained in the white paper.To a certain extent,it enables readers at home and abroad to understand China’s stance on energy issues and the positive image of China in energy ecology.It also awaken readers’awareness of environmental protection and acquire good habits of resource conservation to be in harmony between human and nature for sustainable development. 展开更多
关键词 TRANsITIVITY Ecological discourse analysis Energy in China’s new era
下载PDF
Conceptual Analysis of Self-Management in Patients with Hypertension
3
作者 Li Yang Yutian Hao +4 位作者 Liling Zhong Shilin Xu Saiqiong Zhong Yanying Lu Hui Liu 《Journal of Clinical and Nursing Research》 2024年第5期356-368,共13页
Objective:To clarify the concept of self-management in hypertensive patients by analyzing the definition,attributes,and measurement tools through a literature review.Methods:An Internet-based search of the databases w... Objective:To clarify the concept of self-management in hypertensive patients by analyzing the definition,attributes,and measurement tools through a literature review.Methods:An Internet-based search of the databases was conducted using Academic Search Complete,Medical Line,CINAHL,Health Source:Nursing/Scholarly Edition,and Google Scholar.In the search process,keywords or free text were combined by using Boolean operators,with the search terms“self of management”or“self-management,”“concept*analysis”or“concept*definition,”and Walker and Avant’s concept analysis method was used.Results:Analysis of relevant literature summarized the conceptual attributes of self-management in hypertensive patients as the active participation of patients in the treatment process;the presence of interaction provided by patients and health care providers;the use of certain health management tools;and the aim of maintaining and improving the health status and living capacity of hypertensive patients.Conclusion:The concept of self-management for hypertensive patients was clarified,which helps to promote the application of hypertensive self-management in clinical work and improve outcomes and quality of life for patients with hypertension. 展开更多
关键词 HYPERTENsION sELF-MANAGEMENT Concept analysis Walker and Avant’s concept analysis method
下载PDF
Discourse Analysis of the Belt and Road Initiative From the Perspective of Central Asian Countries: A Case Study of the Republic of Kazakhstan
4
作者 CHEN Jia LIU Shumin +1 位作者 FU Da’an SHAO Di 《Journalism and Mass Communication》 2024年第2期96-100,共5页
This study employs Norman Fairclough’s Critical Discourse Analysis(CDA)three-dimensional model,using the Republic of Kazakhstan as a case study,to delve into the discourse construction of China’s Belt and Road Initi... This study employs Norman Fairclough’s Critical Discourse Analysis(CDA)three-dimensional model,using the Republic of Kazakhstan as a case study,to delve into the discourse construction of China’s Belt and Road Initiative(BRI)in Central Asian countries.Through detailed analysis of policy documents,media reports,and public discussions in Central Asian countries,this paper reveals how the BRI constructs specific social practices,discourse events,and textual meanings within these nations.The findings indicate that through this global development strategy,China has not only strengthened its economic ties with Central Asian countries but has also exerted profound influences on political,cultural,and social levels. 展开更多
关键词 Belt and Road Initiative Central Asian countries discourse analysis Norman Fairclough’s three-dimensional model
下载PDF
Shear wave splitting analysis of local earthquakes from dense arrays in Shimian,Sichuan 被引量:2
5
作者 Sha Liu Baofeng Tian 《Earthquake Science》 2023年第1期52-63,共12页
The Shimian area of Sichuan sits at the junction of the Bayan Har block.Sichuan-Yunnan rhombic block,and Yangtze block,where several faults intersect.This region features intense tectonic activity and frequent earthqu... The Shimian area of Sichuan sits at the junction of the Bayan Har block.Sichuan-Yunnan rhombic block,and Yangtze block,where several faults intersect.This region features intense tectonic activity and frequent earthquakes.In this study,we used local seismic waveform data recorded using dense arrays deployed in the Shimian area to obtain the shear wave splitting parameters at 55 seismic stations and thereby determine the crustal anisotropic characteristics of the region.We then analyzed the crustal stress pattern and tectonic setting and explored their relationship in the study area.Although some stations returned a polarization direction of NNW-SSE.a dominant polarization direction of NW-SE was obtained for the fast shear wave at most seismic stations in the study area.The polarization directions of the fast shear wave were highly consistent throughout the study-area.This orientation was in accordance with the direction of the regional principal compressive stress and parallel to the trend of the Xianshuihe and Daliangshan faults.The distribution of crustal anisotropy in this area was affected by the regional tectonic stress field and the fault structures.The mean delay time between fast and slow shear waves was 3.83 ms/km.slightly greater than the values obtained in other regions of Sichuan.This indicates that the crustal media in our study area had a high anisotropic strength and also reveals the influence of tectonic complexity resulting from the intersection of multiple faults on the strength of seismic anisotropy. 展开更多
关键词 shear wave splitting polarization direction of the fast shear wave regional principal compressive stress dense array Citation:Liu s and Tian BF(2023).shear wave splitting analysis of local earthquakes from dense arrays in shimian sichuan.
下载PDF
The Application of Deep Brain Stimulation for Parkinson’s Disease on the Motor Pathway:A Bibliometric Analysis across 10 Years
6
作者 Yong-tang SONG Yan-bo LIU +2 位作者 Hong-bing XIANG Anne Manyande Zhi-gang HE 《Current Medical Science》 SCIE CAS 2023年第6期1247-1257,共11页
Background and Objective Since its initial report by James Parkinson in 1817,Parkinson’s disease(PD)has remained a central subject of research and clinical advancement.The disease is estimated to affect approximately... Background and Objective Since its initial report by James Parkinson in 1817,Parkinson’s disease(PD)has remained a central subject of research and clinical advancement.The disease is estimated to affect approximately 1%of adults aged 60 and above.Deep brain stimulation,emerging as an alternative therapy for end-stage cases,has offered a lifeline to numerous patients.This review aimed to analyze publications pertaining to the impact of deep brain stimulation on the motor pathway in patients with PD over the last decade.Methods Data were obtained from the Web of Science Core Collection through the library of Huazhong University of Science and Technology(China).The search strategy encompassed the following keywords:“deep brain stimulation”,“Parkinson’s disease”,“motor pathway”,and“human”,from January 1,2012,to December 1,2022.Additionally,this review visualized the findings using the Citespace software.Results The results indicated that the United States,the United Kingdom,Germany,and China were the primary contributors to this research field.University College London,Capital Medical University,and Maastricht University were the top 3 research institutions in the research area.Tom Foltynie ranked first with 6 publications,and the journals of Brain and Brain Stimulation published the greatest number of relevant articles.The prevailing research focal points in this domain,as determined by keywords“burst analysis”,“encompassed neuronal activity”,“nucleus”,“hyper direct pathway”,etc.Conclusion This study has provided a new perspective through bibliometric analysis of the deep brain stimulation therapy for treating patients with PD,which can shed light on future research to advance our comprehension of this particular field of study. 展开更多
关键词 deep brain stimulation Parkinson’s disease motor pathway bibliometric analysis
下载PDF
Sensor-Based Gait Analysis for Parkinson’s Disease Prediction
7
作者 Sathya Bama B Bevish Jinila Y 《Intelligent Automation & Soft Computing》 SCIE 2023年第5期2085-2097,共13页
Parkinson’s disease is identified as one of the key neurodegenerative disorders occurring due to the damages present in the central nervous system.The cause of such brain damage seems to be fully explained in many res... Parkinson’s disease is identified as one of the key neurodegenerative disorders occurring due to the damages present in the central nervous system.The cause of such brain damage seems to be fully explained in many research studies,but the understanding of its functionality remains to be impractical.Specifically,the development of a quantitative disease prediction model has evolved in recent decades.Moreover,accelerometer sensor-based gait analysis is accepted as an important tool for recognizing the walking behavior of the patients during the early prediction and diagnosis of Parkinson’s disease.This type of minimal infrastructure equipment helps in analyzing the Parkinson’s gait properties without affecting the common behavioral patterns during the clinical practices.Therefore,the Accelerometer Sensor-based Parkinson’s Disease Identi-fication System(ASPDIS)is introduced with a kernel-based support vector machine classifier model to make an early prediction of the disease.consequently,the proposed classifier can easily predict various severity levels of Parkinson’s disease from the sensor data.The performance of the proposed classifier is com-pared against the existing models such as random forest,decision tree,and k-near-est neighbor classifiers respectively.As per the experimental observation,the proposed classifier has more capability to differentiate Parkinson’s from non-Parkinson patients depending upon the severity levels.Also,it is found that the model has outperformed the existing classifiers concerning prediction time and accuracy respectively. 展开更多
关键词 Brain disorders gait analysis Parkinson’s disease support vector machine classifier healthcare system
下载PDF
A Comprehensive Bibliometric Analysis of China’s Free Trade Zones:Status and Evolutionary Trends
8
作者 HUANG Lixia XU Miaoling 《Chinese Business Review》 2023年第3期127-140,共14页
The China free trade zone,crucial for advancing a new open economy,has gained significant attention lately.We analyzed 885 papers from Peking University Core and CSSCI journals(2012-2023)using CiteSpace for visualizat... The China free trade zone,crucial for advancing a new open economy,has gained significant attention lately.We analyzed 885 papers from Peking University Core and CSSCI journals(2012-2023)using CiteSpace for visualization.Our research results indicate that the literature on China’s free trade zone peaked with 171 articles in 2015,and gradually returned to an average of 45 articles per year.The main research focuses in this field include“institutional innovation”,“negative list”,“financial innovation”,“financial openness”,“opening up to the outside world”,and“economic growth”.In addition,cutting-edge analysis indicates that“dual circulation”and“blockchain”are future research trends.The main authors of the literature include Yang Bin,Zhu Xiaolin,Yuan Bo,Li Meng,Zhao Liang,and others.Their affiliated institutions,research institutes,and universities have not yet formed a clear core circle of authors;The top three research institutions with the highest number of publications are the International Trade and Economic Cooperation Research Institute of the Ministry of Commerce,Kaiyuan Law School of Shanghai Jiao Tong University,and the Comprehensive Research Institute of the Free Trade Zone of Sun Yatsen University.This article delves into the current hot topics and progress in the research of China’s free trade zones,providing important references and inspirations for future scholars in this field. 展开更多
关键词 China’s free trade zone bibliometric analysis CITEsPACE
下载PDF
Diagnostic performance of texture analysis in the differential diagnosis of perianal fistulising Crohn’s disease and glandular anal fistula
9
作者 Xin Zhu Dan-Dan Ye +2 位作者 Jian-Hua Wang Jing Li Shao-Wei Liu 《World Journal of Gastrointestinal Surgery》 2023年第5期882-891,共10页
BACKGROUND Perianal fistulising Crohn's disease(PFCD)and glandular anal fistula have many similarities on conventional magnetic resonance imaging.However,many patients with PFCD show concomitant active proctitis,b... BACKGROUND Perianal fistulising Crohn's disease(PFCD)and glandular anal fistula have many similarities on conventional magnetic resonance imaging.However,many patients with PFCD show concomitant active proctitis,but only few patients with glandular anal fistula have active proctitis.AIM To explore the value of differential diagnosis of PFCD and glandular anal fistula by comparing the textural feature parameters of the rectum and anal canal in fat suppression T2-weighted imaging(FS-T2WI).METHODS Patients with rectal water sac implantation were screened from the first part of this study(48 patients with PFCD and 22 patients with glandular anal fistula).Open-source software ITK-SNAP(Version 3.6.0,http://www.itksnap.org/)was used to delineate the region of interest(ROI)of the entire rectum and anal canal wall on every axial section,and then the ROIs were input in the Analysis Kit software(version V3.0.0.R,GE Healthcare)to calculate the textural feature parameters.Textural feature parameter differences of the rectum and anal canal wall between the PFCD group vs the glandular anal fistula group were analyzed using Mann-Whitney U test.The redundant textural parameters were screened by bivariate Spearman correlation analysis,and binary logistic regression analysis was used to establish the model of textural feature parameters.Finally,diagnostic accuracy was assessed by receiver operating characteristic-area under the curve(AUC)analysis.RESULTS In all,385 textural parameters were obtained,including 37 parameters with statistically significant differences between the PFCD and glandular anal fistula groups.Then,16 texture feature parameters remained after bivariate Spearman correlation analysis,including one histogram parameter(Histogram energy);four grey level co-occurrence matrix(GLCM)parameters(GLCM energy_all direction_offset1_SD,GLCM entropy_all direction_offset4_SD,GLCM entropy_all direction_offset7_SD,and Haralick correlation_all direction_offset7_SD);four texture parameters(Correlation_all direction_offset1_SD,cluster prominence_angle 90_offset4,Inertia_all direction_offset7_SD,and cluster shade_angle 45_offset7);five grey level run-length matrix parameters(grey level nonuniformity_angle 90_offset1,grey level nonuniformity_all direction_offset4_SD,long run high grey level emphasis_all direction_offset1_SD,long run emphasis_all direction_offset4_SD,and long run high grey level emphasis_all direction_offset4_SD);and two form factor parameters(surface area and maximum 3D diameter).The AUC,sensitivity,and specificity of the model of textural feature parameters were 0.917,85.42%,and 86.36%,respectively.CONCLUSION The model of textural feature parameters showed good diagnostic performance for PFCD.The texture feature parameters of the rectum and anal canal in FS-T2WI are helpful to distinguish PFCD from glandular anal fistula. 展开更多
关键词 Anal fistula Crohn’s diseases Magnetic resonance imaging Texture analysis Differential diagnosis
下载PDF
Suboptimal Rayleigh damping coefficients in seismic analysis of viscously-damped structures 被引量:7
10
作者 Pan Danguang Chen Genda Wang Zuocai 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2014年第4期653-670,共18页
An optimization method for the consistent evaluation of two Rayleigh damping coefficients is proposed. By minimizing an objective function such as an error term of the peak displacement of a structure, the two coeffic... An optimization method for the consistent evaluation of two Rayleigh damping coefficients is proposed. By minimizing an objective function such as an error term of the peak displacement of a structure, the two coefficients can be determined with response spectral analysis. The optimization method degenerates into the conventional method used in current practices when only two modes of vibration are included in the objective function. Therefore, the proposed method with all significant modes included for simplicity in practical applications results in suboptimal damping coefficients. The effects of both spatial distribution and frequency content of excitations as well as structural dynamic characteristics on the evaluation of Rayleigh damping coefficients were investigated with a five-story building structure. Two application examples with a 62-story high-rise building and a 840 m long cable-stayed bridge under ten earthquake excitations demonstrated the accuracy and effectiveness of the proposed method to account for all of the above effects. 展开更多
关键词 rayleigh damping response spectral analysis structural dynamics structural analysis optimization method
下载PDF
A Survey of English Translation Studies of Lu You’s Poetry Based on the Data Analysis of Domestic Academic Journals (2001-2022)
11
作者 Dongfang Chen Jiesen Ma 《Open Journal of Applied Sciences》 2023年第6期847-857,共11页
This article presents a comprehensive analysis of the current state of research on the English translation of Lu You’s poetry, utilizing a data sample comprising research papers published in the CNKI Full-text Databa... This article presents a comprehensive analysis of the current state of research on the English translation of Lu You’s poetry, utilizing a data sample comprising research papers published in the CNKI Full-text Database from 2001 to 2022. Employing rigorous longitudinal statistical methods, the study examines the progress achieved over the past two decades. Notably, domestic researchers have displayed considerable interest in the study of Lu You’s English translation works since 2001. The research on the English translation of Lu You’s poetry reveals a diverse range of perspectives, indicating a rich body of scholarship. However, several challenges persist, including insufficient research, limited translation coverage, and a noticeable focus on specific poems such as “Phoenix Hairpin” in the realm of English translation research. Consequently, there is ample room for improvement in the quality of research output on the English translation of Lu You’s poems, as well as its recognition within the academic community. Building on these findings, it is argued that future investigations pertaining to the English translation of Lu You’s poetry should transcend the boundaries of textual analysis and encompass broader theoretical perspectives and research methodologies. By undertaking this shift, scholars will develop a more profound comprehension of Lu You’s poetic works and make substantive contributions to the field of translation studies. Thus, this article aims to bridge the gap between past research endeavors and future possibilities, serving as a guide and inspiration for scholars to embark on a more nuanced and enriching exploration of Lu You’s poetry as well as other Chinese literature classics. 展开更多
关键词 Lu You’s Poetry English Translation studies Data analysis Translation Criticism
下载PDF
Expansion of Linear Analysis of Rayleigh-Taylor Interface Instability of Metal Materials 被引量:2
12
作者 Xinbo Bai Tao Wang +1 位作者 Yuxuan Zhu Guoqiang Luo 《World Journal of Mechanics》 2018年第4期94-106,共13页
The linear analysis of the Rayleigh-Taylor instability in metal material is extended from the perfect plastic constitutive model to the Johnson-Cook and Steinberg-Guinan constitutive model, and from the constant loadi... The linear analysis of the Rayleigh-Taylor instability in metal material is extended from the perfect plastic constitutive model to the Johnson-Cook and Steinberg-Guinan constitutive model, and from the constant loading to a time-dependent loading. The analysis is applied to two Rayleigh-Taylor instability experiments in aluminum and vanadium with peak pressures of 20 GPa and 90 GPa, and strain rates of 6 × 106 s&minus;1 and 3 × 107 s&minus;1 respectively. When the time-dependent loading and the Steinberg-Guinan constitutive model are used in the linear analysis, the analytic results are in close agreement with experiments quantitatively, which indicates that the method in this paper is applicable to the Rayleigh-Taylor instability in aluminum and vanadium metal materials under high pressure and high strain rate. From these linear analyses, we find that the constitutive models and the loading process are of crucial importance in the linear analysis of the Rayleigh-Taylor instability in metal material, and a better understanding of the Rayleigh-Taylor instability in metals is gained. These results will serve as important references for evolving high-pressure, high-strain-rate experiments and numerical simulations. 展开更多
关键词 Linear analysis rayleigh-TAYLOR INsTABILITY TIME-DEPENDENT LOADING CONsTITUTIVE Model
下载PDF
Cloning and Sequence Analysis of 16S rRNA and COI Gene in Mitochondrial DNA of Scortum barcoo 被引量:2
13
作者 张龙岗 安丽 +2 位作者 董学飒 孟庆磊 付佩胜 《Agricultural Science & Technology》 CAS 2010年第7期176-178,182,共4页
[Objective] The aim was to provide molecular biological basis for the researches on the genetic resources,genetic relationship among species and phyletic evolution of S.barcoo.[Method] PCR amplification and sequencing... [Objective] The aim was to provide molecular biological basis for the researches on the genetic resources,genetic relationship among species and phyletic evolution of S.barcoo.[Method] PCR amplification and sequencing were used to study the 16S rRNA and COI gene fragments.[Result] As for 16S rRNA gene fragments,nucleotide sequences of 791 bp were obtained,and the A,T,G and C contents in this fragment were 31.6%,21.4%,20.4% and 26.7%respectively.As for the COI gene fragments,the size was 631 bp and the A,T,G And C contents were 27.7%,23.6%,29.8% and 18.9% respectively.Among these two gene fragments,the content of GC was lower than AT,and AT/GC of these two fragments was 1.13 and 1.05 respectively.[Conclusion] The genetic characteristics of gene fragments of 16S rRNA and COI of S.barcoo suggested that the variation in the same species was relatively low.The sequences of 16S rRNA gene in three samples the same,while the sequences of COI gene was also the same,indicating that these two gene of S.barcoo were conservative. 展开更多
关键词 scortum barcoo 16s rRNA and COI gene sequence analysis
下载PDF
Comparative Analysis of Improving Effects of 12 Maize Populations with Improved S_1 Selection Method
14
作者 孙峰成 冯勇 +6 位作者 付增娟 苏二虎 张来厚 赵瑞霞 刘志雄 石海波 李美娜 《Agricultural Science & Technology》 CAS 2014年第10期1687-1692,1713,共7页
ln this study, 12 maize populations were improved with the improved S1 selection method, aiming to increase the improvement efficiency of maize popula-tions. The results showed that number of rows per spike, number of... ln this study, 12 maize populations were improved with the improved S1 selection method, aiming to increase the improvement efficiency of maize popula-tions. The results showed that number of rows per spike, number of grains per row and 100-grain weight were the three important component traits of maize yield. The highest genetic increment was found in Mengqun 2, fol owed by Mengqun 4, Mengqun 1 and other 7 maize populations. Negative genetic increment was shown in Mengqun 3 and 3 introduced foreign maize populations. Some changes were shown in spikes, plant traits and genetic diversity of maize populations. Based on our results, we concluded that Mengqun 2, Mengqun 4, Zhongzong 7, Mengqun C and Mengqun A could be directly used for the line breeding by selfing for their higher genetic increment of yield and better improvement effects of other agricultural traits. Compared with these 5 populations, the improvement potential of other maize populations was limited for their lower genetic increment. 展开更多
关键词 lmproved s1 selection method Maize population Genetic gain Comparative analysis
下载PDF
GENERAL RELIABILITY ANALYSIS FOR TWO DIMENSIONAL SLOPES
15
作者 揭敏 邓泽贤 李大海 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 1998年第1期36-41,共6页
The reliability analysis, based on the reliability index method, of two dimensional slopes is generalized by taking Sarma′s acceleration as the performance function. That is to say, a general expression of the perfo... The reliability analysis, based on the reliability index method, of two dimensional slopes is generalized by taking Sarma′s acceleration as the performance function. That is to say, a general expression of the performance function is given under various kinds of slice methods, even under various shapes of slice partition, beyond the traditional vertical slice method. A simple example shows explicitly the relationship of four commonly used slice methods in the slope reliability analysis. It is also found that the results of the reliability analysis are basically consistent with those of the stability analysis based on Sarma′s method. 展开更多
关键词 reliability stability analysis two dimen sional slope sarma′s method
下载PDF
K-S变换及其电网超谐波时频分析应用
16
作者 滕召胜 梁成斌 +2 位作者 唐求 张雷鹏 成达 《湖南大学学报(自然科学版)》 EI CAS CSCD 北大核心 2024年第6期128-136,共9页
依据FFT→优化窗→IFFT思路,突破线性时频变换的窗函数积分性能桎梏,实现高性能优化窗函数的线性时频变换应用,建立新型时频变换算法——K-S变换.对信号x(t)的FFT频谱向量进行频移处理后,与该频移点下Kaiser优化窗的频谱向量进行Hadamar... 依据FFT→优化窗→IFFT思路,突破线性时频变换的窗函数积分性能桎梏,实现高性能优化窗函数的线性时频变换应用,建立新型时频变换算法——K-S变换.对信号x(t)的FFT频谱向量进行频移处理后,与该频移点下Kaiser优化窗的频谱向量进行Hadamard乘积,再将乘积结果进行FFT逆变换(IFFT),构造出K-S变换复时频矩阵,由此获得x(t)的时间-频率-幅值、时间-频率-相位三维信息;给出逆变换的数学推导与局部性质、线性性质和变分辨率特性;0~150 kHz电网的稳态与时变超谐波信号仿真实验表明,K-S变换的时域、频域分辨能力均优于流行的短时傅里叶变换、S变换,具有优良的变分辨率性能;0~40 kHz超谐波信号的实测证明,基于K-S变换的超谐波电压幅值测量绝对误差均小于0.032 3 V. 展开更多
关键词 K-s变换 时频分析 Kaiser优化窗 变分辨率特性 电网超谐波
下载PDF
宽负荷下切圆燃煤锅炉H_(2)S分布特性的数值模拟
17
作者 邓磊 袁茂博 +3 位作者 杨家辉 韩磊 姜家豪 车得福 《煤炭学报》 EI CAS CSCD 北大核心 2024年第6期2887-2895,共9页
锅炉采用空气分级燃烧降低NO_(x)排放的同时也提高了主燃区H_(2)S体积分数。炉墙壁面过高的H_(2)S体积分数是加剧水冷壁高温腐蚀的重要因素。为保障新能源并网发电,大型燃煤机组灵活调峰的需求增加,不同负荷下的水冷壁近壁面H_(2)S分布... 锅炉采用空气分级燃烧降低NO_(x)排放的同时也提高了主燃区H_(2)S体积分数。炉墙壁面过高的H_(2)S体积分数是加剧水冷壁高温腐蚀的重要因素。为保障新能源并网发电,大型燃煤机组灵活调峰的需求增加,不同负荷下的水冷壁近壁面H_(2)S分布特性值得关注。通过正交试验分析了切圆燃煤锅炉运行参数对水冷壁近壁面H_(2)S体积分数分布的影响。选取一台超临界600 MW切圆燃煤锅炉建立数值模型,设计L_(16)(4^(5))正交工况,覆盖100%BMCR、75%THA,50%THA以及35%BMCR四种负荷。建立了自定义SO_(x)生成模型以确定燃料硫的析出和转化路径,模型包含多表面反应子模型以描述焦炭与O_(2)/CO_(2)/H_(2)O等3种气体的异相反应,并确定焦炭气化反应消耗量占总消耗量的比例,进而对炉膛H_(2)S空间分布进行了模拟计算。研究表明,近壁面高体积分数H_(2)S区域主要位于投运燃烧器层中最下层燃烧器以下以及最上层燃烧器以上至SOFA层之间,烟气切圆沿炉膛高度增加逐渐增大是造成后一区域H_(2)S体积分数较高的重要原因。35%BMCR负荷下水冷壁重点区域的H_(2)S平均体积分数为364μL/L,明显低于其他负荷。锅炉运行参数对重点区域H_(2)S体积分数影响程度的排序为:锅炉负荷>一次风率>主燃区空气过量系数>假想切圆直径>燃烧器竖直摆角。 展开更多
关键词 切圆燃煤锅炉 宽负荷 H2s分布 正交分析 数值模拟
下载PDF
基于CD-BSMOTE的D-S证据融合变压器故障诊断
18
作者 鲁玲 高诚 +3 位作者 熊威 龚康 马辉 张鑫 《水电能源科学》 北大核心 2024年第5期192-196,共5页
针对变压器油中溶解气体数据集不均衡特性对故障诊断结果的影响,提出一种基于清除临界点改进的边界合成少数类过采样算法均衡数据集和Pearson冲突距离改进D-S证据融合的变压器故障诊断模型。首先,对少数类样本进行均衡化处理,根据K-mean... 针对变压器油中溶解气体数据集不均衡特性对故障诊断结果的影响,提出一种基于清除临界点改进的边界合成少数类过采样算法均衡数据集和Pearson冲突距离改进D-S证据融合的变压器故障诊断模型。首先,对少数类样本进行均衡化处理,根据K-means聚类结果清除处于临界位置的样本;其次,搭建梯度提升树、随机森林、BP神经网络的故障诊断模型,实现变压器故障初步诊断;接着引入Pearson冲突距离改进D-S证据融合模型,实现诊断结果的融合决策;最后,经实际算例分析,诊断精确率达到92.65%。结果表明,所建模型能有效解决数据不平衡对诊断结果的影响,提高故障诊断精度。 展开更多
关键词 故障诊断 油中溶解气体分析 边界合成少数类过采样 Pearson冲突距离 D-s证据融合
下载PDF
基于T-S模糊故障树的驱动电机冷却系统可靠性分析
19
作者 柳炽伟 郭美华 《客车技术与研究》 2024年第2期19-25,共7页
车用驱动电机液压冷却系统存在故障机理不确定等问题。本文应用模糊数描述其故障概率和故障程度,建立驱动电机冷却系统的T-S模糊故障树模型,计算系统模糊可能性,分析各部件的概率重要度和关键重要度,找出影响系统可靠性的关键部件。
关键词 电动汽车 驱动电机 冷却系统 T-s模糊故障树 可靠性分析
下载PDF
Characterization and phylogenetic analysis of a phenanthrene-degrading strain isolated from oil-contaminated soil 被引量:7
20
作者 XIAYing MINHang LUZhen-mei YEYang-fang 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2004年第4期589-593,共5页
Bacterium strain EVA17 was isolated from an oil-contaminated soil, and identified as Sphingomonas sp. based on analysis of 16S rDNA sequence,cellular fatty acid composition and physiological-chemical tests. The salicy... Bacterium strain EVA17 was isolated from an oil-contaminated soil, and identified as Sphingomonas sp. based on analysis of 16S rDNA sequence,cellular fatty acid composition and physiological-chemical tests. The salicylate hydroxylase and catechol 2,3-dioxygenase(C23O) were detected in cell-free lysates, suggesting a pathway for phenanthrene catabolism via salicylate and catechol. Alignment showed that both of the C23O and GST genes of the strain EVA17 had high similarity with homologues of strains from genus Sphingomonas. The phylogenetic analysis based on 16S rDNA and C23O gene sequence indicated that EVA17 should be classified into genus Sphingomonas, although the two phylogenetic trees were slightly different from each other. The results of co-amplification and sequence determination indicated that GST gene should be located upstream of the C23O gene. 展开更多
关键词 PHENANTHRENE 16s rDNA glutathione s-transferase catechol 2 3-dioxygenase phylogenetic analysis
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部