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Marine organism classification method based on hierarchical multi-scale attention mechanism
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作者 XU Haotian CHENG Yuanzhi +1 位作者 ZHAO Dong XIE Peidong 《Optoelectronics Letters》 2025年第6期354-361,共8页
We propose a hierarchical multi-scale attention mechanism-based model in response to the low accuracy and inefficient manual classification of existing oceanic biological image classification methods. Firstly, the hie... We propose a hierarchical multi-scale attention mechanism-based model in response to the low accuracy and inefficient manual classification of existing oceanic biological image classification methods. Firstly, the hierarchical efficient multi-scale attention(H-EMA) module is designed for lightweight feature extraction, achieving outstanding performance at a relatively low cost. Secondly, an improved EfficientNetV2 block is used to integrate information from different scales better and enhance inter-layer message passing. Furthermore, introducing the convolutional block attention module(CBAM) enhances the model's perception of critical features, optimizing its generalization ability. Lastly, Focal Loss is introduced to adjust the weights of complex samples to address the issue of imbalanced categories in the dataset, further improving the model's performance. The model achieved 96.11% accuracy on the intertidal marine organism dataset of Nanji Islands and 84.78% accuracy on the CIFAR-100 dataset, demonstrating its strong generalization ability to meet the demands of oceanic biological image classification. 展开更多
关键词 integrate information different scales hierarchical multi scale attention lightweight feature extraction focal loss efficientnetv marine organism classification oceanic biological image classification methods convolutional block attention module
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Improvement of X-Band Polarization Radar Melting Layer Recognition by the Bayesian Method and ITS Impact on Hydrometeor Classification 被引量:7
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作者 Jianli MA Zhiqun HU +1 位作者 Meilin YANG Siteng LI 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2020年第1期105-116,共12页
Using melting layer(ML)and non-melting layer(NML)data observed with the X-band dual linear polarization Doppler weather radar(X-POL)in Shunyi,Beijing,the reflectivity(ZH),differential reflectivity(ZDR),and correlation... Using melting layer(ML)and non-melting layer(NML)data observed with the X-band dual linear polarization Doppler weather radar(X-POL)in Shunyi,Beijing,the reflectivity(ZH),differential reflectivity(ZDR),and correlation coefficient(CC)in the ML and NML are obtained in several stable precipitation processes.The prior probability density distributions(PDDs)of the ZH,ZDR and CC are calculated first,and then the probabilities of ZH,ZDR and CC at each radar gate are determined(PBB in the ML and PNB in the NML)by the Bayesian method.When PBB>PNB the gate belongs to the ML,and when PBB<PNB the gate belongs to the NML.The ML identification results with the Bayesian method are contrasUsing melting layer(ML)and non-melting layer(NML)data observed with the X-band dual linear polarization Doppler weather radar(X-POL)in Shunyi,Beijing,the reflectivity(ZH),differential reflectivity(ZDR),and correlation coefficient(CC)in the ML and NML are obtained in several stable precipitation processes.The prior probability density distributions(PDDs)of the ZH,ZDR and CC are calculated first,and then the probabilities of ZH,ZDR and CC at each radar gate are determined(PBB in the ML and PNB in the NML)by the Bayesian method.When PBB>PNB the gate belongs to the ML,and when PBB<PNB the gate belongs to the NML.The ML identification results with the Bayesian method are contrasted under the conditions of the independent PDDs and joint PDDs of the ZH,ZDR and CC.The results suggest that MLs can be identified effectively,although there are slight differences between the two methods.Because the values of the polarization parameters are similar in light rain and dry snow,it is difficult for the polarization radar to distinguish them.After using the Bayesian method to identify the ML,light rain and dry snow can be effectively separated with the X-POL observed data.ted under the conditions of the independent PDDs and joint PDDs of the ZH,ZDR and CC.The results suggest that MLs can be identified effectively,although there are slight differences between the two methods.Because the values of the polarization parameters are similar in light rain and dry snow,it is difficult for the polarization radar to distinguish them.After using the Bayesian method to identify the ML,light rain and dry snow can be effectively separated with the X-POL observed data. 展开更多
关键词 X-band polarimetric radar Bayesian method melting layer identification hydrometeor classification
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Three-dimensional Extension of the Unit-Feature Spatial Classification Method for Cloud Type 被引量:1
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作者 张成伟 郁凡 +1 位作者 王晨曦 杨建宇 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2011年第3期601-611,共11页
We describe how the Unit-Feature Spatial Classification Method(UFSCM) can be used operationally to classify cloud types in satellite imagery efficiently and conveniently.By using a combination of Interactive Data Lang... We describe how the Unit-Feature Spatial Classification Method(UFSCM) can be used operationally to classify cloud types in satellite imagery efficiently and conveniently.By using a combination of Interactive Data Language(IDL) and Visual C++(VC) code in combination to extend the technique in three dimensions(3-D),this paper provides an efficient method to implement interactive computer visualization of the 3-D discrimination matrix modification,so as to deal with the bi-spectral limitations of traditional two dimensional(2-D) UFSCM.The case study of cloud-type classification based on FY-2C satellite data (0600 UTC 18 and 0000 UTC 10 September 2007) is conducted by comparison with ground station data, and indicates that 3-D UFSCM makes more use of the pattern recognition information in multi-spectral imagery,resulting in more reasonable results and an improvement over the 2-D method. 展开更多
关键词 cloud-type classification unit-feature spatial classification method three dimensions
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An overview of thermoelectric films:Fabrication techniques,classification,and regulation methods 被引量:1
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作者 Jing-jing Feng Wei Zhu Yuan Deng 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第4期12-26,共15页
Thermoelectric materials have aroused widespread concern due to their unique ability to directly convert heat to electricity without any moving parts or noxious emissions.Taking advantages of two-dimensional structure... Thermoelectric materials have aroused widespread concern due to their unique ability to directly convert heat to electricity without any moving parts or noxious emissions.Taking advantages of two-dimensional structures of thermoelectric films,the potential applications of thermoelectric materials are diversified,particularly in microdevices.Well-controlled nanostructures in thermoelectric films are effective to optimize the electrical and thermal transport,which can significantly improve the performance of thermoelectric materials.In this paper,various physical and chemical approaches to fabricate thermoelectric films,including inorganic,organic,and inorganic–organic composites,are summarized,where more attentions are paid on the inorganic thermoelectric films for their excellent thermoelectric responses.Additionally,strategies for enhancing the performance of thermoelectric films are also discussed. 展开更多
关键词 thermoelectric films fabrication techniques classification regulation methods
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Research Dynamics of the Classification Methods of Remote Sensing Images 被引量:1
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作者 Yan ZHANG Baoguo WU Dong WANG 《Asian Agricultural Research》 2013年第3期118-122,共5页
As the key technology of extracting remote sensing information,the classification of remote sensing images has always been the research focus in the field of remote sensing. The paper introduces the classification pro... As the key technology of extracting remote sensing information,the classification of remote sensing images has always been the research focus in the field of remote sensing. The paper introduces the classification process and system of remote sensing images. According to the recent research status of domestic and international remote sensing classification methods,the new study dynamics of remote sensing classification,such as artificial neural networks,support vector machine,active learning and ensemble multi-classifiers,were introduced,providing references for the automatic and intelligent development of remote sensing images classification. 展开更多
关键词 REMOTE SENSING IMAGES classification methods CLASS
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ESTIMATION OF 2-D DOA USING NON-CIRCULAR MUSIC METHOD FOR UNIFORM CIRCULAR AND RECTANGULAR ARRAYS 被引量:1
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作者 Li Rui Shi Xiaowei +2 位作者 Xu Le Bi Xiaojun Li Ping 《Journal of Electronics(China)》 2011年第1期38-43,共6页
This paper extends the Non-Circular MUltiple SIgnal Classification(MUSIC)(NC-MUSIC) method for the common array geometries including Uniform Circular Arrays(UCAs) and Uniform Rectangular Arrays(URAs),which enables the... This paper extends the Non-Circular MUltiple SIgnal Classification(MUSIC)(NC-MUSIC) method for the common array geometries including Uniform Circular Arrays(UCAs) and Uniform Rectangular Arrays(URAs),which enables the algorithm to estimate 2-D Direction Of Arrival(DOA).A comparison between UCAs and URAs of NC-MUSIC is made in this paper.The simulations show that the NC-MUSIC method doubles the maximum estimation number of standard MUSIC.Using non-circular signals,the performance of URAs is improved remarkably while the improvement of UCAs is not so significantly.Moreover,the influence of arrays structures on the NC-MUSIC method is discussed. 展开更多
关键词 Non-circular signals MUltiple SIgnal classification(music) Array 2-D Direction Of Arrival(DOA)
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Classification of Preparation Methods and Wearability of Smart Textiles 被引量:2
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作者 FANG Jialu DU Jianxia 《Journal of Donghua University(English Edition)》 CAS 2022年第4期379-391,共13页
In recent years,smart textiles have attracted the attention of scholars from all walks of life,but there is an imbalance between functionality and usability,which affects their marketization process.Firstly,five repre... In recent years,smart textiles have attracted the attention of scholars from all walks of life,but there is an imbalance between functionality and usability,which affects their marketization process.Firstly,five representative smart textiles are introduced and their respective wearability is described around preparation methods.Secondly,it is concluded that the preparation methods of smart textiles can be divided into two categories:fiber methods and finishing methods.The fiber methods refer to making smart fibers into smart textiles.Textiles made by fiber methods are breathable and feel good in the hand,but the mechanical properties are influenced by the production equipment,and the process cost is high.The finishing methods refer to the functional finishing of ordinary textiles.Although the finishing method is simple and convenient,it may reduce the comfort of the textile.Finally,applications and new research in various fields of smart textiles are presented with promising prospects.It is anticipated that this review will serve as a theoretical basis for future research and development of smart textiles.Researchers are expected to create new technologies to overcome the tension between functionality and usability,as well as to increase user comfort and convenience. 展开更多
关键词 smart textiles classification of preparation method WEARABILITY FUNCTIONALITY fabric comfort
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Music Genre Classification Using DenseNet and Data Augmentation 被引量:1
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作者 Dao Thi Le Thuy Trinh Van Loan +1 位作者 Chu Ba Thanh Nguyen Hieu Cuong 《Computer Systems Science & Engineering》 SCIE EI 2023年第10期657-674,共18页
It can be said that the automatic classification of musical genres plays a very important role in the current digital technology world in which the creation,distribution,and enjoyment of musical works have undergone h... It can be said that the automatic classification of musical genres plays a very important role in the current digital technology world in which the creation,distribution,and enjoyment of musical works have undergone huge changes.As the number ofmusic products increases daily and themusic genres are extremely rich,storing,classifying,and searching these works manually becomes difficult,if not impossible.Automatic classification ofmusical genres will contribute to making this possible.The research presented in this paper proposes an appropriate deep learning model along with an effective data augmentation method to achieve high classification accuracy for music genre classification using Small Free Music Archive(FMA)data set.For Small FMA,it is more efficient to augment the data by generating an echo rather than pitch shifting.The research results show that the DenseNet121 model and data augmentation methods,such as noise addition and echo generation,have a classification accuracy of 98.97%for the Small FMA data set,while this data set lowered the sampling frequency to 16000 Hz.The classification accuracy of this study outperforms that of the majority of the previous results on the same Small FMA data set. 展开更多
关键词 music genre classification Small FMA DenseNet CNN GRU data augmentation
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An integrated classification method for thematic mapper imagery of plain and highland terrains 被引量:1
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作者 Shan-long LU Xiao-hua SHEN +6 位作者 Le-jun ZOU Chang-jiang LI Yan-jun MAO Gui-fang ZHANG Wen-yuan WU Ying LIU Zhong ZHANG 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2008年第6期858-866,共9页
The classification of thematic mapper imagery in areas with strong topographic variations has proven problematic in the past using a single classifier, due to the changing sun illumination geometry. This often results... The classification of thematic mapper imagery in areas with strong topographic variations has proven problematic in the past using a single classifier, due to the changing sun illumination geometry. This often results in the phenomena of identical object with dissimilar spectrum and different objects with similar spectrum. In this paper, an integrated classification method that combines a decision tree with slope data, tasseled cap transformation indices and maximum likelihood classifier is introduced, to find an optimal classification method for thematic mapper imagery of plain and highland terrains. A Landsat 7 ETM+ image acquired over Hangzhou Bay, in eastern China was used to test the method. The results indicate that the performance of the inte- grated classifier is acceptably good in comparison with that of the existing most widely used maximum likelihood classifier. The integrated classifier depends on hypsography (variation in topography) and the characteristics of ground truth objects (plant and soil). It can greatly reduce the influence of the homogeneous spectrum caused by topographic variation. This integrated classifier might potentially be one of the most accurate classifiers and valuable tool for land cover and land use mapping of plain and highland terrains. 展开更多
关键词 Image classification Land cover and land use Thematic mapper imagery Plain and highland terrains Integratedclassification method
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A Brief Analysis of the Application of Situational Teaching Method in Primary School Music Class 被引量:1
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作者 Yuchen Zhang 《Journal of Contemporary Educational Research》 2020年第10期62-65,共4页
Music situational teaching method aims to mobilize the students’thoughts in a natural state so as to enhance the attractiveness and efficiency of music classes.In the process of this method,some specific situational ... Music situational teaching method aims to mobilize the students’thoughts in a natural state so as to enhance the attractiveness and efficiency of music classes.In the process of this method,some specific situational are designed according to the characteristics of music and under the guidance of psychology,methodology,pedagogy and other theories,and various sensory organs are employed.Different from traditional teaching method,situational teaching method creates learning situational for students,which is consistent with the characteristics of primary school students’physical and mental development and maximizes students’experience and feeling of music. 展开更多
关键词 music situational teaching method Primary school music education music class
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A NEW METHOD FOR CLASSIFICATION OF ROCK DRILLABILITY
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作者 Lu, Fan Central-South University of Technology, Changsha 410083, China 《中国有色金属学会会刊:英文版》 CSCD 1993年第3期76-80,共5页
A New method of rock drillability classification for impregnated diamond drilling is recommended. The essence of the method is comparing the area of the slots cut respectively on a standard synthetic rock sample and t... A New method of rock drillability classification for impregnated diamond drilling is recommended. The essence of the method is comparing the area of the slots cut respectively on a standard synthetic rock sample and the rock sample being classified by one diamond saw to determine the rock drillability in diamond core drilling. This method has the advantages of good in simulation and stable in comparison standard. 展开更多
关键词 ROCK DRILLABILITY classification DIAMOND core DRILLING cutting-comparison method
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On Eigen-Matrix Translation Method for Classification of Biological Data
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作者 JIANG Hao QIU Yushan +1 位作者 CHENG Xiaoqing CHING Waiki 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2015年第5期1212-1230,共19页
Driven by the challenge of integrating large amount of experimental data, classification technique emerges as one of the major and popular tools in computational biology and bioinformatics research. Machine learning m... Driven by the challenge of integrating large amount of experimental data, classification technique emerges as one of the major and popular tools in computational biology and bioinformatics research. Machine learning methods, especially kernel methods with Support Vector Machines (SVMs) are very popular and effective tools. In the perspective of kernel matrix, a technique namely Eigen- matrix translation has been introduced for protein data classification. The Eigen-matrix translation strategy has a lot of nice properties which deserve more exploration. This paper investigates the major role of Eigen-matrix translation in classification. The authors propose that its importance lies in the dimension reduction of predictor attributes within the data set. This is very important when the dimension of features is huge. The authors show by numerical experiments on real biological data sets that the proposed framework is crucial and effective in improving classification accuracy. This can therefore serve as a novel perspective for future research in dimension reduction problems. 展开更多
关键词 classification dimension reduction eigen-matrix translation glycan data kernel method(KM) support vector machine (SVM)
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A classification method of building structures based on multi-feature fusion of UAV remote sensing images
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作者 Haoguo Du Yanbo Cao +6 位作者 Fanghao Zhang Jiangli Lv Shurong Deng Yongkun Lu Shifang He Yuanshuo Zhang Qinkun Yu 《Earthquake Research Advances》 CSCD 2021年第4期38-47,共10页
In order to improve the accuracy of building structure identification using remote sensing images,a building structure classification method based on multi-feature fusion of UAV remote sensing image is proposed in thi... In order to improve the accuracy of building structure identification using remote sensing images,a building structure classification method based on multi-feature fusion of UAV remote sensing image is proposed in this paper.Three identification approaches of remote sensing images are integrated in this method:object-oriented,texture feature,and digital elevation based on DSM and DEM.So RGB threshold classification method is used to classify the identification results.The accuracy of building structure classification based on each feature and the multi-feature fusion are compared and analyzed.The results show that the building structure classification method is feasible and can accurately identify the structures in large-area remote sensing images. 展开更多
关键词 Remote sensing image Building structure classification Multi-feature fusion Object-oriented classification method Texture feature classification method DSM and DEM elevation classification method RGB threshold classification method
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Using Hybrid and Diversity-Based Adaptive Ensemble Method for Binary Classification
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作者 Xing Fan Chung-Horng Lung Samuel A. Ajila 《International Journal of Intelligence Science》 2018年第3期43-74,共32页
This paper proposes an adaptive and diverse hybrid-based ensemble method to improve the performance of binary classification. The proposed method is a non-linear combination of base models and the application of adapt... This paper proposes an adaptive and diverse hybrid-based ensemble method to improve the performance of binary classification. The proposed method is a non-linear combination of base models and the application of adaptive selection of the most suitable model for each data instance. Ensemble method, an important machine learning technique uses multiple single models to construct a hybrid model. A hybrid model generally performs better compared to a single individual model. In a given dataset the application of diverse single models trained with different machine learning algorithms will have different capabilities in recognizing patterns in the given training sample. The proposed approach has been validated on Repeat Buyers Prediction dataset and Census Income Prediction dataset. The experiment results indicate up to 18.5% improvement on F1 score for the Repeat Buyers dataset compared to the best individual model. This improvement also indicates that the proposed ensemble method has an exceptional ability of dealing with imbalanced datasets. In addition, the proposed method outperforms two other commonly used ensemble methods (Averaging and Stacking) in terms of improved F1 score. Finally, our results produced a slightly higher AUC score of 0.718 compared to the previous result of AUC score of 0.712 in the Repeat Buyers competition. This roughly 1% increase AUC score in performance is significant considering a very big dataset such as Repeat Buyers. 展开更多
关键词 Bigdata ANALYTICS MACHINE Learning ADAPTIVE ENSEMBLE methods BINARY classification
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Classification of musical hallucinations and the characters along with neural-molecular mechanisms of musical hallucinations associated with psychiatric disorders
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作者 Xin Lian Wei Song +1 位作者 Tian-Mei Si Naomi Zheng Lian 《World Journal of Psychiatry》 SCIE 2024年第9期1386-1396,共11页
BACKGROUND Musical hallucinations(MH)involve the false perception of music in the absence of external stimuli which links with different etiologies.The pathomechanisms of MH encompass various conditions.The etiologica... BACKGROUND Musical hallucinations(MH)involve the false perception of music in the absence of external stimuli which links with different etiologies.The pathomechanisms of MH encompass various conditions.The etiological classification of MH is of particular importance and offers valuable insights to understand MH,and further to develop the effective treatment of MH.Over the recent decades,more MH cases have been reported,revealing newly identified medical and psychiatric causes of MH.Functional imaging studies reveal that MH activates a wide array of brain regions.An up-to-date analysis on MH,especially on MH comorbid psychiatric conditions is warranted.AIM To propose a new classification of MH;to study the age and gender differences of MH in mental disorders;and neuropathology of MH.METHODS Literatures searches were conducted using keywords such as“music hallucination,”“music hallucination and mental illness,”“music hallucination and gender difference,”and“music hallucination and psychiatric disease”in the databases of PubMed,Google Scholar,and Web of Science.MH cases were collected and categorized based on their etiologies.The t-test and ANOVA were employed(P<0.05)to compare the age differences of MH different etiological groups.Function neuroimaging studies of neural networks regulating MH and their possible molecular mechanisms were discussed.RESULTS Among the 357 yielded publications,294 MH cases were collected.The average age of MH cases was 67.9 years,with a predominance of females(66.8%females vs 33.2%males).MH was classified into eight groups based on their etiological mechanisms.Statistical analysis of MH cases indicates varying associations with psychiatric diagnoses.CONCLUSION We carried out a more comprehensive review of MH studies.For the first time according to our knowledge,we demonstrated the psychiatric conditions linked and/or associated with MH from statistical,biological and molecular point of view. 展开更多
关键词 PATHOMECHANISM Etiological factors classification Gender difference Neuropathway Psychotic musical hallucination and non-psychotic musical hallucination Neuropathway Biological and molecular mechanism
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Man-Computer Interactive Method on Cloud Classification Based on Bispectral Satellite Imagery
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《Advances in Atmospheric Sciences》 SCIE CAS CSCD 1997年第3期102-111,共10页
Man-ComputerInteractiveMethodonCloudClasificationBasedonBispectralSateliteImageryYuFan(郁凡),LiuChangsheng(刘长盛... Man-ComputerInteractiveMethodonCloudClasificationBasedonBispectralSateliteImageryYuFan(郁凡),LiuChangsheng(刘长盛)DepartmentofAtmo... 展开更多
关键词 Man-Computer Interactive method on Cloud classification Based on Bispectral Satellite IMAGERY 刘长
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Material balance method and classification of non-uniform water invasion mode for water-bearing gas reservoirs considering the effect of water sealed gas 被引量:1
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作者 Tan Xiaohua Peng Gangzhen +6 位作者 Li Xiaoping Chen Yingli Xu Xiaoling Kui Mingqing Li Qian Yang Guojun Xiao Heng 《Natural Gas Industry B》 2021年第4期353-358,共6页
In order to clarify the characteristics of non-uniform water invasion in water-bearing gas reservoirs,it is necessary to introduce the nonuniformity coefficient(A)and water invasion constant(B)to characterize the non-... In order to clarify the characteristics of non-uniform water invasion in water-bearing gas reservoirs,it is necessary to introduce the nonuniformity coefficient(A)and water invasion constant(B)to characterize the non-uniformity degree of reservoir physical properties and the activity degree of peripheral water,respectively,based on the dual mechanism of water invasion to recharge the formation energy and seal off the gas in the reservoir.Then,the material balance method considering the phenomenon of water sealed gas was established.On this basis,the water invasion characteristic curve chart of water-bearing gas reservoirs was plotted,and the non-uniform water invasion mode was classified based on the example gas reservoir.And the following research results were obtained.First,in the water invasion characteristic curve chart of waterbearing gas reservoirs which is plotted based on the material balance method considering the influence of water sealed gas,the upper right area and the lower left area are defined as recharge area and seal area,respectively.By taking A=0 and B=2 as the boundary,the recharge area is divided into strong recharge area and weak recharge area.By taking A=2 and B=2 as the boundary,the seal area is divided into strong seal area and weak seal area.And correspondingly there are four water invasion modes,i.e.,strong recharge,weak recharge,weak seal and strong seal.Second,for fractured gas reservoirs,the non-uniformity degree of reservoir physical properties is high,and water sealed gas can be formed easily after water invasion.The dimensionless relative pseudo-pressure data of this type of gas reservoir is located in the seal area of the water invasion characteristic curve chart.Third,for the gas reservoirs whose reservoir physical properties are relatively uniform,the dimensionless relative pseudo-pressure data is located in the recharge area of the water invasion characteristic curve chart,and the recharge effect of water invasion on formation energy is greater than the weakening effect of water sealed gas on formation energy.Fourth,with the increase of A,the non-uniformity degree of reservoir physical properties increases,the water invasion characteristic curve shifts from the upper right to the lower left,and the recovery factor of gas reservoir decreases continuously.With the increase of B,the recharge effect of water invasion on formation energy and the weakening effect of water sealed gas on formation energy are both weakened,the distribution range of water invasion characteristic curve narrows to the recharge/seal boundary,and the corresponding range of gas reservoir recovery factor also narrows. 展开更多
关键词 Water-bearing gas reservoir Material balance method Water invasion characteristic Water sealed gas Non-uniformity coefficient Water invasion constant Water invasion mode classification
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Comparative Study of the Geomagnetic Activity Effect on foF2 Variation as Defined by the Two Classification Methods at Dakar Station over Solar Cycle Phases
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作者 Sibri Alphonse Sandwidi Doua Allain Gnabahou Frédéric Ouattara 《International Journal of Geosciences》 2020年第8期501-517,共17页
This paper aims to establish a comparison between both geomagnetic activity classification methods on foF2 diurnal variation over solar cycle phases. It concerns first a comparison of geomagnetic activity occurrences ... This paper aims to establish a comparison between both geomagnetic activity classification methods on foF2 diurnal variation over solar cycle phases. It concerns first a comparison of geomagnetic activity occurrences according to both classification methods;and second the geomagnetic effect on foF2 diurnal variation profiles as defined for the equatorial latitudes. The occurrences of the different disturbed geomagnetic activities (recurrent activity (RA), shock activity (SA) and fluctuant activity (FA)) according to both classifications (ancient classification (AC) and new classification (NC)) have been studied at Dakar ionosonde station (Lat: 14.8°N;Long: 342.6°E). Regarding both classifications, the RA occurs more during the decreasing phase. And it’s observed that the RA occurs the most during the increasing phase for the AC and during the minimum phase for the NC. The maximum gap of occurrence (<img src="Edit_e4627ea9-9a9a-4473-9017-202d04a16377.bmp" alt="" /><span><span style="font-family:Verdana;">) between both classifications is <span style="font-size:10.0pt;font-family:;" "=""><span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">&#45</span></span></span><span style="font-family:;" "=""><span style="font-family:Verdana;">11.1%</span><span style="font-family:Verdana;"> (for the negative value which is observed during the increasing phase) and </span><span style="font-family:Verdana;">+16.74%</span><span style="font-family:Verdana;"> (for the positive one which is observed during the decreasing phase). The occurrence of the SA in relation with both classifications is the lowest during the minimum phase and the maximum occurrence is observed during the maximum and decreasing phases, for the AC, with a value close to </span><span style="font-family:Verdana;">37%</span><span style="font-family:Verdana;"> and for the NC at the maximum phase with a percentage of </span><span style="font-family:Verdana;">54.47%</span><span><span style="font-family:Verdana;">. The maximum gap of occurrence (</span><img src="Edit_20fa141b-ecee-4e06-8024-144ba0969395.bmp" alt="" /></span></span><span style="font-family:Verdana;">) between both classifications is <span style="font-size:10.0pt;font-family:;" "=""><span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">&#45</span></span></span><span style="font-family:;" "=""><span style="font-family:Verdana;">17.85%</span><span style="font-family:Verdana;"> (for the negative value which is observed at maximum phase) and </span><span style="font-family:Verdana;">+13.53%</span><span style="font-family:Verdana;"> (for the positive one which is observed during the decreasing phase). For both classifications, the FA occurs the least during the minimum phase and the most during the maximum phase for the AC and at maximum and decreasing phases with percentage values of occurrence of roughly </span><span style="font-family:Verdana;">37%</span><span><span style="font-family:Verdana;"> for the NC. The maximum gap of occurrence (</span><img src="Edit_eecb8939-783e-4d43-b92c-80c528c1890b.bmp" alt="" /><span style="font-family:Verdana;"></span></span></span><span style="font-family:Verdana;">) between both classifications is <span style="font-size:10.0pt;font-family:;" "=""><span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">&#45</span></span>10% (for the negative value which is observed during the decreasing phase) and </span><span style="font-family:;" "=""><span style="font-family:Verdana;">+20.11%</span><span style="font-family:Verdana;"> (for the positive one which is observed during the maximum phase). foF2 diurnal profiles throughout solar cycle phases concerning the AC and the NC have been compared. The FA diurnal profiles don’t present a difference. The RA and the SA present a difference during minimum and increasing phases and the least at maximum and decreasing phases.</span></span></span> 展开更多
关键词 Geomagnetic Activity classification method Solar Cycle Phases foF2 Diurnal Profile
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Symmetry Classification of Partial Differential Equations Based on Wu's Method
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作者 TIAN Yi WAN Jianxiong 《Journal of Donghua University(English Edition)》 CAS 2021年第2期187-192,共6页
Lie algorithm combined with differential form Wu's method is used to complete the symmetry classification of partial differential equations(PDEs)containing arbitrary parameter.This process can be reduced to solve ... Lie algorithm combined with differential form Wu's method is used to complete the symmetry classification of partial differential equations(PDEs)containing arbitrary parameter.This process can be reduced to solve a large system of determining equations,which seems rather difficult to solve,then the differential form Wu's method is used to decompose the determining equations into a series of equations,which are easy to solve.To illustrate the usefulness of this method,we apply it to some test problems,and the results show the performance of the present work. 展开更多
关键词 Lie algorithm differential form Wu's method determining equation symmetry classification partial differential equation(PDE)
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叶端振动信号频谱分析的前后向平滑MUSIC法
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作者 平艳 王增坤 +3 位作者 范志飞 袁超 杨志勃 乔百杰 《振动与冲击》 北大核心 2025年第10期208-214,共7页
叶端定时是航空发动机叶片叶端振动非接触测量的有效手段,但其采样模式决定了所采信号具有高度欠采样特征,需要进行抗混叠频谱分析从而提取转子叶片固有频率这一关键指标。利用了前向平滑策略的改进多重信号分类法(multiple sIgnal clas... 叶端定时是航空发动机叶片叶端振动非接触测量的有效手段,但其采样模式决定了所采信号具有高度欠采样特征,需要进行抗混叠频谱分析从而提取转子叶片固有频率这一关键指标。利用了前向平滑策略的改进多重信号分类法(multiple sIgnal classification,MUSIC)能实现抗混叠但无法充分发挥平滑方法的优势。因此,提出适用于叶端定时信号处理的前后向平滑MUSIC法,通过建立传感器的对称布局条件,利用前后向平滑方法代替前向平滑方法,得到更准确的自相关矩阵估计,进而提高叶片固有频率估计性能,并通过仿真和试验验证了在样本数量、算法参数等相同的情况下,前后向平滑MUSIC法的混叠与噪声抑制能力得到了提升。 展开更多
关键词 叶端定时 发动机转子叶片 多重信号分类法(music) 空间平滑 频率估计
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