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Near-infrared reflectance spectroscopy reveals wide variation in major components of sesame seeds from Africa and Asia 被引量:11
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作者 Komivi Dossa Xin Wei +7 位作者 Marème Niang Pan Liu Yanxin Zhang Linhai Wang Boshou Liao Ndiaga Cissé Xiurong Zhang Diaga Diouf 《The Crop Journal》 SCIE CAS CSCD 2018年第2期202-206,共5页
Sesame is an important oilseed crop in Africa and Asia, owing to its high nutritional quality seed and market value. Variation in sesame seed components including oil, oleic acid,linoleic acid, and protein was investi... Sesame is an important oilseed crop in Africa and Asia, owing to its high nutritional quality seed and market value. Variation in sesame seed components including oil, oleic acid,linoleic acid, and protein was investigated by near-infrared reflectance spectrometry in 139 samples collected from different countries. Oil and protein contents were between 40.8%and 60.3%(mean 53.0%) and 15.5% to 25.5%(mean 20.4%), respectively. Linoleic acid,ranging from 31.8% to 52.4%(mean 46%) was more abundant than oleic acid(31.8%–50.6%,mean 38.1%). Light-seeded samples displayed higher nutritional quality, as they were richer in oil, protein, and linoleic acid than dark seeds. Samples from Africa had higher oil and linoleic acid contents, while Asian samples had higher oleic content. The analysis revealed West African sesame cultivars containing especially high levels of seed components, which may command high market values. Two clusters of sesame samples grouped by seed composition were obtained, including one cluster with high oil and oleic acid content and the other with high protein and linoleic acid content. This study revealed that sesame samples from Africa and Asia harbor high variation for major seed components and also provided background information for breeding high-nutrition varieties according to the demands of sesame seed markets. 展开更多
关键词 Sesamum indicum Major SEED components variation ASIA AFRICA NIRS
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Natural variation of main biochemical components,morphological and yield traits among a panel of 87 tea [Camellia sinensis(L.) O. Kuntze] cultivars 被引量:1
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作者 Fawad Zaman EZhang +9 位作者 Li Xia Xielong Deng Muhammad Ilyas Ahmad Ali Fei Guo Pu Wang Mingle Wang Yu Wang Dejiang Ni Hua Zhao 《Horticultural Plant Journal》 SCIE CAS CSCD 2023年第3期563-576,共14页
Many attentions have been previously focused to identify the multiple biochemical components related to tea quality and health benefits,however, the natural variation of biochemical components present in tea germplasm... Many attentions have been previously focused to identify the multiple biochemical components related to tea quality and health benefits,however, the natural variation of biochemical components present in tea germplasm has not been adequately evaluated. In this study, the main biochemical components, leaf morphological and yield characteristics were evaluated for four rounds of tea leaves in a panel of 87 elite tea cultivars suitable for black, green, or oolong tea. Significant variations were observed among the tea cultivars, as well as seasonal differences in the levels of the free amino acid(FAA), caffeine(CAF), tea polyphenols(TP), water extract(WE) and TP to FAA ratio(TP/FAA). Results showed that the average levels of FAA showed a seasonal change, with the highest level of 4.0% in the 1st spring tea in the cultivars suitable for green tea and the lowest of 3.2% in summer tea in the cultivars suitable for black tea. The average CAF content was highest 3.2% in the cultivars suitable for oolong tea in the 1st spring and the lowest 2.5% in the cultivars suitable for green tea in summer. Limited seasonal and varietal variations were noticed in the average levels of WE among the three categories of tea. In addition, significant natural variation of the morphological characteristics, bud length varying from 2.5 cm to 8.7 cm, bud density from 190.3 buds · m-2to 1 730.3 buds · m-2, mature leaves biomass from 128.4 kg · hm-2to 2 888.4 kg · hm-2, and yield component traits of 100 buds(one bud with two leaves) dry weight from 3.7 g to37.7 g, tea yield/round from 444.6 kg · hm-2to 905.3 kg · hm-2, were observed. The aim of our evaluation was not only to identify the advantages of seasonal and clonal variations but also to provide a new viewpoint for their further application. Representative accessions were selected from the germplasm to promote the establishment of an inherent biochemical constituent expressing the quality of black, green, and oolong tea. The findings might be utilized to establish early selection criteria to enhance the tea breeding and production program. 展开更多
关键词 Camellia sinensis Biochemical components GERMPLASM Natural variation Morphology Yield
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Spatial Correlation Anomalies of the Diurnal Variation of the Geomagnetic Vertical Component before the Yingjiang MS 6.1 and Ludian MS 6.5 Earthquakes
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作者 Dai Yong Feng Zhisheng +1 位作者 Yang Yanming Gegen 《Earthquake Research in China》 CSCD 2018年第4期521-532,共12页
Significant anomalies were observed at the geomagnetic stations in the southwest region of China before the Yingjiang M_S6. 1 earthquake and the Ludian M_S6. 5 earthquake in 2014.We processed the geomagnetic vertical ... Significant anomalies were observed at the geomagnetic stations in the southwest region of China before the Yingjiang M_S6. 1 earthquake and the Ludian M_S6. 5 earthquake in 2014.We processed the geomagnetic vertical component diurnal variation data by the spatial correlation method. The results show that during the period from April 1 to May 20,2014,there existed quasi-synchronous decrease changes in the coefficient curves between the five geomagnetic stations of Guiyang,Hechi,Nanshan,Muli,Yongning and Xinyi and Hongshan stations. Furthermore,there was a high gradient zone in the normalized correlation coefficient contour map with background values removed. The epicenters of the Yingjiang M_S6. 1 earthquake and the Ludian M_S6. 5 earthquake are located in the gradient zone or near the gradient zone. 展开更多
关键词 Yingjiang MS6.1 EARTHQUAKE Ludian MS6.5 EARTHQUAKE GEOMAGNETISM VERTICAL component Abnormal variation
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Genetic Variation and Heritability Estimates for Bunch Yield, Bunch Components and Vegetative Traits in Oil Palm Interspecific Hybrids
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作者 Mohd Din Amiruddin Rajanaidu Nookiah +1 位作者 Jalani Sukaimi Zakri Abdul Hamid 《Journal of Agricultural Science and Technology(A)》 2015年第3期162-173,共12页
Progeny testing of oil palm interspecific hybrids was conducted in four trials in Kluang, Ulu Paka, Teluk Intan and Carey Island, Malaysia. The interspecific hybrids (O × P) were created according to the North ... Progeny testing of oil palm interspecific hybrids was conducted in four trials in Kluang, Ulu Paka, Teluk Intan and Carey Island, Malaysia. The interspecific hybrids (O × P) were created according to the North Carolina Model I (NCM I) mating design, using Elaeis oleifera (0) and Elaeis guineensis var. pisifera (P) as the maternal and paternal parents, respectively. Differences among O, P and O-within-P were determined by the performance (bunch yield, components and vegetative traits) of the progenies. There were significant differences among P for fresh fruit bunch (FFB) yield, bunch number (BN) and average bunch weight (ABW) in Kluang, Ulu Paka and Teluk Intan, but not in Carey Island. FFB yield was generally higher on coastal soils (Teluk Intan and Carey Island) than inland soils (Kluang and Ulu Paka). Heritability was calculated based on the intraclass correlation. Heritability estimates for these three yield components were variable, depending on the breeding material and environment in which the materials were tested. Fruit to bunch (F/B) and oil to bunch (O/B) of parthenocarpic fruits were important in determining the overall O/B of the interspecific hybrids. The O x P hybrids in Kluang showed the lowest height increment with only a mean of 14.0 cm/year, whereas in Ulu Paka and Teluk Intan, the values were higher at 24.0 cm/year and 25.0 cm/year, respectively. The study showed that the FFB yields ofoil palm interspecific hybrids performed better in coastal soils than inland soils. 展开更多
关键词 Oil palm interspecific hybrids genetic variation heritability estimates bunch yield bunch components vegetativetraits.
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Spatial and Temporal Variations of Daily Ranges of the Geomagnetic Vertical Component in the Chinese Mainland
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作者 Li Junhui Li Qi +3 位作者 Wang Xingzhou He Kang Tao Yuechao Chen Jun 《Earthquake Research in China》 2013年第1期91-100,共10页
In this paper, we use the daily ranges of the vertical magnetic intensity of approximately 76 geomagnetic stations from January 1, 2008 to December 31, 2010 to analyze the spatial and temporal characteristics of Z ran... In this paper, we use the daily ranges of the vertical magnetic intensity of approximately 76 geomagnetic stations from January 1, 2008 to December 31, 2010 to analyze the spatial and temporal characteristics of Z ranges. The results are summarized as follows: (1) Temporally, we use regressive analysis and FFT analysis to analyze the data. The results show that the Z component daily ranges of all stations have an obvious cyclical variation, the computed Fourier spectra of all data sets have clearly resolved the required periodicities in the data, in the form of distinct peaks at days 365, 183, 22, and 73, and the power spectra of day 365 is the highest in all periods. (2) In terms of spatial variation, the daily ranges show nonlinear variation with latitude in China. The results show the existence of a point of inflexion (maximal value point) nearby at about 25°N, the daily ranges of Z rise from 15°~25°N and have a good linear decrease variation along with 25°~50°N. (3) Compared with the spatial and temporal variations of Z daily ranges with the Sq current inversion, we found that the spatial and temporal characteristics of Z ranges are decided mainly by the spatio-temporal evolution of the Sq current system. (4) If the latitudes of the maximum amplitudes of variation of the vertical component in the geomagnetic quiet days are roughly taken as the latitudes corresponding to the foci of Sq overhead current system, we can see that these latitudes of foci become higher in summer, are lowest in winter and highest during Equinoxes, displaying conspicuous monthly and daily variations. For two successive geomagnetic quiet days, the latitudes of foci may vary ten degrees. 展开更多
关键词 Chinese mainland GEOMAGNETIC Daily ranges of Z component Spatial and temporal variations
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Phenotypic variation in Phoebe bournei populations preserved in the primary distribution area 被引量:19
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作者 Yingang Li Xinhong Liu +2 位作者 Junwei Ma Xiaomian Zhang Li-an Xu 《Journal of Forestry Research》 SCIE CAS CSCD 2018年第1期35-44,共10页
Phoebe bournei(Hemsl.) Yang is a rare and protected plant in China. This study was conducted to determine the phenotypic variation in this species and to document phenotypic variation within and among populations of... Phoebe bournei(Hemsl.) Yang is a rare and protected plant in China. This study was conducted to determine the phenotypic variation in this species and to document phenotypic variation within and among populations of P. bournei. Nested analysis of variance, coefficient of variation, multiple comparisons, principal component analysis(PCA) and correlation analysis were used to analyze ten phenotypic traits in ten natural populations of P.bournei from both the northeastern and the primary region of the range of this species. Significant differences among and within populations were observed in leaf and seed phenotypic traits. Variation among populations(34.92%)was greater than that within populations(26.19%). The mean phenotypic differentiation coefficient was 53.77% among populations, indicating that variation among populations comprised the majority of the phenotypic variation of P. bournei. The coefficient of variance(CV) of ten traits varied from 6.44 to 18.45%, with an average of 12.03%.The CV of leaf traits among populations(15.64%) was higher than that of seed traits(8.60%), indicating that seed traits were more stable. The results from CV and PCA indicated that leaf area, leaf length and thousand seed weight were the main factors accounting for the observed phenotypic variations. Significant or highly significant correlations were observed among most leaf and/or in seed phenotypic traits, whereas no significant correlations were observed between phenotypic traits and geographic factors.Based on cluster analysis, the ten populations can be divided into three clusters. These clusters were not a result of geographic distances. 展开更多
关键词 Phenotypic variation Phoebe bournei POPULATION Principal component analysis Protection and utilization
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DYNAMIC VARIATIONS OF WATER QUALITY IN TAIHU LAKE AND MULTIVARIATE ANALYSIS OF ITS INFLUENTIAL FACTORS 被引量:9
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作者 Cai Qiming Gao Xiyun Chen Yuwei Ma Shengwei Nanjing Institute of Geography and Limnology, CAS, Nanjing 210008 People’s Republic of ChinaMartin Dokulil Institute of Limnology, Austria 《Journal of Geographical Sciences》 SCIE CSCD 1997年第3期72-82,共11页
Dynamic variation of water quality in Meiliang Bay and part of West Taihu Lake has been analysed based on data from 1991 to 1992. Principal Component Analysis is used to reveal the mutual relationships of various fact... Dynamic variation of water quality in Meiliang Bay and part of West Taihu Lake has been analysed based on data from 1991 to 1992. Principal Component Analysis is used to reveal the mutual relationships of various factors. It is shown that there existis an obvious spatial and temporal variation in the main factors of water quality. Annual values of TP, CON, TN, Chl-a and conductivity decrease evidently from inner Meiliang Bay to the outer from north to south. TP and TN fluctuate seasonally with much higher value in winter. This is particularly true for the mouth of Liangxi River. In addition, the Chl-1 has a synchronous variation with water temperature, although being lagged a little, and closely relates to TP and TN. Finally, the results from Principal Component Analysis show that TP, TN, SS (or SD), water temperature and Chl-a are the most influential factors to water qualuty in this area, and both suspensions and algae can contribute to transparency to Taihu Lake. 展开更多
关键词 Taihu Lake dynamic variation water quality principal component analysis.
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Chemometric study of spatial variations of environmental and ecological characteristics in the Zhujiang River (Pearl River) Estuary and adjacent waters 被引量:6
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作者 SONG Xingyu HUANG Liangmin +4 位作者 ZHANG Jianlin YIN Kedong LIU Sheng TAN Yehui YIN Jianqiang 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2011年第4期60-74,共15页
Chemometric approach based on principal component analysis(PCA) was utilized to examine the spatial variances of environmental and ecological characteristics in the Zhujiang River(Pearl River) Estuary and adjacent... Chemometric approach based on principal component analysis(PCA) was utilized to examine the spatial variances of environmental and ecological characteristics in the Zhujiang River(Pearl River) Estuary and adjacent waters(ZREAW) in the South China Sea. The PCA result shows that the ZREAW can be divided into different zones according to the principal components and geographical locations of the study stations,and indicates that there are distinct regional variances on environmental features and the corresponding phytoplankton biomass and community structures among different areas. The spatial distribution of ecological features was implied to be influenced by various degrees of the different water resources,such as the Pearl River discharges,the coastal current and the oceanic water from the South China Sea. The variation of the biomass maximum zone and the complex impacts on the spatial distributions of phytoplankton biomass and production were also evaluated. 展开更多
关键词 principal component analysis spatial variations environmental conditions ecological distribution PHYTOPLANKTON Zhujiang River (Pearl River) Estuary
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A Modeling Study of Seasonal Variation of Atmospheric Aerosols over East Asia 被引量:5
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作者 LI Jiawei HAN Zhiwei 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2012年第1期101-117,共17页
In this study, a regional air quality model system (RAQMS) was applied to investigate the spatial distributions and seasonal variations of atmospheric aerosols in 2006 over East Asia. Model validations demonstrated ... In this study, a regional air quality model system (RAQMS) was applied to investigate the spatial distributions and seasonal variations of atmospheric aerosols in 2006 over East Asia. Model validations demonstrated that RAQMS was able to reproduce the evolution processes of aerosol components reasonably well. Ground-level PM10 (particles with aerodynamic diameter ≤10 μm) concentrations were highest in spring and lowest in summer and were characterized by three maximum centers: the Taklimakan Desert (-1000 μg m^-3), the Gobi Desert (-400 μg m^-3), and the Huabei Plain (- 300 μg m^-3) of China. Vertically, high PM10 concentrations ranging from 100 μg m-3 to 250 μg m-3 occurred from the surface to an altitude of 6000 m at 30°-45°N in spring. In winter, the vertical gradient was so large that most aerosols were restricted in the boundary layer. Both sulfate and ammonium reached their highest concentrations in autumn, while nitrate reached its maximum level in winter. Black carbon and organic carbon aerosol concentrations reached maximums in winter. Soil dust were strongest in spring, whereas sea salt exerted the strongest influence on the coastal regions of eastern China in summer. The estimated burden of anthropogenic aerosols was largest in winter (1621 Gg) and smallest in summer (1040 Gg). The sulfate burden accounted for -42% of the total anthropogenic aerosol burden. The dust burden was about twice the anthropogenic aerosol burden, implying the potentially important impacts of the natural aerosols on air quality and climate over East Asia. 展开更多
关键词 East Asia aerosol components model simulation spatial distribution seasonal variation column burden
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Relationship between land cover and monsoon interannual variations in east Asia 被引量:5
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作者 XIANG Bao, LIU Ji-yuan (Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China) 《Journal of Geographical Sciences》 SCIE CSCD 2002年第1期42-48,共7页
Asian monsoon have multiple forms of variations such as seasonal variation, intra-seasonal variation, interannual variation, etc. The interannual variations have not only yearly variations but also variations among se... Asian monsoon have multiple forms of variations such as seasonal variation, intra-seasonal variation, interannual variation, etc. The interannual variations have not only yearly variations but also variations among several years. In general, the yearly variations are described with winter temperature and summer precipitation, and the variations among several years are reflected by circulation of ENSO events. In this study, at first, we analyze the relationship between land cover and interannual monsoon variations represented by precipitation changes using Singular Value Decomposition method based on the time series precipitation data and 8km NOAA AVHRR NDVI data covering 1982 to 1993 in east Asia. Furthermore, after confirmation and reclassification of ENSO events which are recognized as the strong signal of several year monsoon variation, using the same time series NDVI data during 1982 to 1993 in east Asia, we make a Principle Component Analysis and analyzed the correlation of the 7th component eigenvectors and Southern Oscillation Index (SOI) that indicates the characteristic of ENSO events, and summed up the temporal-spatial distribution features of east Asian land cover’s inter-annual variations that are being driven by changes of ENSO events. 展开更多
关键词 east Asian land cover monsoon climate interannual variations Singular Value Decomposition ENSO events Principle component Analysis
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DYNAMIC VARIATIONS OF WATER QUALITY IN TAIHU LAKE AND MULTIVARIATE ANALYSIS OF ITS INFLUENTIAL FACTORS 被引量:2
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作者 Qiming Cai Xiyun Gao +2 位作者 Yuwei Chen Shengwei Ma Dokulil Martin 《Chinese Geographical Science》 SCIE CSCD 1996年第4期364-374,共11页
DYNAMIC VARIATIONS OF WATER QUALITY IN TAIHU LAKE AND MULTIVARIATE ANALYSIS OF ITS INFLUENTIAL FACTORSDYNAMI... DYNAMIC VARIATIONS OF WATER QUALITY IN TAIHU LAKE AND MULTIVARIATE ANALYSIS OF ITS INFLUENTIAL FACTORSDYNAMICVARIATIONSOFWATE... 展开更多
关键词 Taihu LAKE DYNAMIC variation of WATER QUALITY principal component ANALYSIS
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THE INTERDECADAL VARIATION OF THE SOUTH ASIAN HIGH AND ITS ASSOCIATION WITH THE SEA SURFACE TEMPERATURE OF TROPICAL AND SUBTROPICAL REGIONS 被引量:2
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作者 PENG Li-xia ZHU Wei-jun +4 位作者 LI Zhong-xian NI Dong-hong CHEN Hai-shan PAN Lin-lin LIU Yu-bao 《Journal of Tropical Meteorology》 SCIE 2018年第1期111-122,共12页
This study aims to explore the interdecadal variation of South Asian High(SAH) and its relationship with SST(sea surface temperature) of the tropical and subtropical regions by using the NCEP/NCAR monthly reanalysis d... This study aims to explore the interdecadal variation of South Asian High(SAH) and its relationship with SST(sea surface temperature) of the tropical and subtropical regions by using the NCEP/NCAR monthly reanalysis data from 1948 to 2012, based on the NCAR CAM 3.0 general circulation model. The results show that: 1) the intensity of SAH represents a remarkable interdecadal variation characteristic, the intensity of SAH experienced from weak to strong at the late 1970 s, and after the late 1970 s, its strength is enhanced and the area is expanded in the east-west direction.The expansion degree is greater westward than eastward, while it is opposite in summer. 2) Corresponding to the interdecadal variation of SAH intensity, after the late 1970 s, the divergent component of wind field has two ascending and three descending areas. Of the two ascending areas, one is located in the East Pacific, the other location varies with the season from the Indian Ocean in winter to the South China Sea and West Pacific in summer. Three descending areas are located in the north-central Africa, the East Asia and the Middle Pacific region respectively. 3) Corresponding to the interdecadal variation of SAH intensity, the rotational component of wind field at the lower level is an anomalous cyclone over the South China Sea and West Pacific in summer, while in winter, it is an anomalous cyclone over the Indian Ocean, and an anomalous anticyclone over the equatorial Middle Pacific. 4) Numerical simulations show that the interdecadal variation of SAH is closely related to the SST of the tropical and subtropical regions. The SST of Indian Ocean plays an important role in winter, while in summer, the SST of the South China Sea and West Pacific plays an important role, and the SST of the East Pacific also plays a certain role. 展开更多
关键词 South Asian high interdecadal variation divergent component rotational component SST
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Wavenumber-4 spectral component extracted from TIMED/SABER observations 被引量:2
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作者 Xing Li WeiXing Wan +1 位作者 JinBin Cao ZhiPeng Ren 《Earth and Planetary Physics》 CSCD 2020年第5期436-448,共13页
The wavenumber spectral components WN4 at the mesosphere and low thermosphere(MLT)altitudes(70–10 km)and in the latitude range between±45°are obtained from temperature data(T)observed by the Sounding of the... The wavenumber spectral components WN4 at the mesosphere and low thermosphere(MLT)altitudes(70–10 km)and in the latitude range between±45°are obtained from temperature data(T)observed by the Sounding of the Atmosphere using Broadband Emission Radiometry(SABER)instruments on board the National Aeronautics and Space Administration(NASA)’s Thermosphere–Ionosphere–Mesosphere Energetics and Dynamics(TIMED)spacecraft during the 11-year solar period from 2002 to 2012.We analyze in detail these spectral components WNk and obtain the main properties of their vertical profiles and global structures.We report that all of the wavenumber spectral components WNk occur mainly around 100 km altitude,and that the most prominent component is the wavenumber spectral component WN4 structure.Comparing these long duration temperature data with results of previous investigations,we have found that the yearly variation of spectral component WN4 is similar to that of the eastward propagating non-migrating diurnal tide with zonal wavenumber 3(DE3)at the low latitudes,and to that of the semi-diurnal tide with zonal wavenumber 2(SE2)at the mid-latitudes:the amplitudes of the A4 are larger during boreal summer and autumn at the low-latitudes;at the mid-latitudes the amplitudes have a weak peak in March.In addition,the amplitudes of component WN4 undergo a remarkable short period variation:significant day-to-day variation of the spectral amplitudes A4 occurs primarily in July and September at the low-latitudes.In summary,we conclude that the non-migrating tides DE3 and SE2 are likely to be the origins,at the low-latitudes and the mid-latitudes in the MLT region,respectively,of the observed wavenumber spectral component WN4. 展开更多
关键词 TIMED observations wavenumber spectral components non-migrating tides short period variation
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Multivariate Spatial and Temporal Analysis to Study the Variation of Physico-Chemical Parameters in Litani River, Lebanon
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作者 Ali Hayek Samir Abbad Andaloussi +3 位作者 Nabil Tabaja Joumana Toufaily Evelyne Garnie-Zarli Tayssir Hamieh 《American Journal of Analytical Chemistry》 2021年第11期373-391,共19页
Water quality of Litani River was deteriorated due to rapid population growth and industrial and agricultural activity. Multivariate analysis of spatio-temporal variation of water quality is useful to improve the proj... Water quality of Litani River was deteriorated due to rapid population growth and industrial and agricultural activity. Multivariate analysis of spatio-temporal variation of water quality is useful to improve the projects of water quality management and treatment of the river. In this work, analysis of samples from different locations at different seasons was investigated. The spatio-temporal variation of physico-chemical parameters of the water was determined. A total of 11 water quality parameters were monitored over 12 months during 2018 at 3 sites located in different areas of the river. Multivariate statistical techniques were used to study the spatio-temporal evolution of the studied parameters and the correlation between the different factors. Principal Component Analysis (PCA) was applied to the responsible factors for water quality variations during wet and dry periods. The multivariate analysis of variance (MANOVA) was also applied to the same factors and gives the best results for both spatial and temporal analysis. A black point of agricultural, industrial and sewage water pollution was identified in Jeb-Jennine station from the high concentrations of ammonia, sulfate and phosphate. This difference was proved by the major changes in the values of the parameters from one station to the other. Jeb-Jennine represents a main pollution area in the river. The high ammonia, sulfate and phosphate concentrations result from the important agricultural, industrial and sewage water pollution in the area. A high bacterial activity was highlighted in Jeb-Jennine and Quaroun stations because of the presence of the high nitrite concentrations in the two locations. All parameters are highly affected by climate factors, especially temperature and precipitation. TDS, salinity, electrical conductivity and the concentrations of all pollutants increase during wet season affected by the runoff. Other factors can affect the water quality of the river for example geographical features of the region and seasonal human activity like tourism. The correlation between different parameters was evaluated using PCA statistical method. This correlation is not stable, and evolves between wet and dry season. 展开更多
关键词 Water Quality Litani River Principal component Analysis Seasonal variation Spatial variation
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Dynamics of vector solitons in two-component Bose-Einstein condensates with time-dependent interactions and harmonic potential
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作者 周政 俞慧友 颜家壬 《Chinese Physics B》 SCIE EI CAS CSCD 2010年第1期46-50,共5页
We present two kinds of exact vector-soliton solutions for coupled nonlinear Schrodinger equations with time- varying interactions and time-varying harmonic potential. Using the variational approach, we investigate th... We present two kinds of exact vector-soliton solutions for coupled nonlinear Schrodinger equations with time- varying interactions and time-varying harmonic potential. Using the variational approach, we investigate the dynamics of the vector solitons. It is found that the two bright sol/tons oscillate about slightly and pass through each other around the equilibration state which means that they are stable under our modeh At the same time, we obtain the opposite situation for dark-dark solitons. 展开更多
关键词 two-component Bose Einstein condensates vector solitons the variational approach
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基于参数优化变分模态分解的信号降噪方法
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作者 何玉洁 李新娥 贺俊 《现代电子技术》 北大核心 2025年第2期70-76,共7页
针对心电信号中肌电干扰噪声难以去除的问题,提出一种基于参数优化变分模态分解(VMD)的信号降噪方法。通过设计动态边界策略和反向种群生成方式,对白鲸优化(BWO)算法进行改进;采用改进白鲸优化算法对VMD参数自适应寻优,确定分解层数K与... 针对心电信号中肌电干扰噪声难以去除的问题,提出一种基于参数优化变分模态分解(VMD)的信号降噪方法。通过设计动态边界策略和反向种群生成方式,对白鲸优化(BWO)算法进行改进;采用改进白鲸优化算法对VMD参数自适应寻优,确定分解层数K与惩罚因子α;对含噪心电信号进行分解,得到k个本征模态函数(IMF)分量,同时采用相关系数法进行有效模态和含噪模态识别;对噪声主导的模态分量采用小波阈值降噪,并重构信号主导模态与降噪后模态。对仿真信号与含真实肌电干扰的心电信号进行降噪处理,实验结果表明,所提方法去噪效果优于小波阈值去噪法、EMD法、EMD-小波阈值去噪法,真实含噪的心电信号经该方法去噪后自相关系数可达0.91以上。 展开更多
关键词 变分模态分解 信号降噪 参数优化 改进白鲸优化算法 心电信号 IMF分量 小波阈值降噪 肌电干扰
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特香型白酒基酒贮存期风味成分平衡过程的解析
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作者 祝云飞 林培 +3 位作者 吴生文 谢芳迁 曾婷婷 蔡珊 《中国酿造》 北大核心 2025年第1期65-72,共8页
以40个陶坛贮存的特香型白酒新基酒为研究对象,每3个月进行检测,跟踪检测2年。基于Pearson相关性分析,从化学反应平衡角度解析基酒总酸/总酯、乳酸/乳酸乙酯、乙酸/乙酸乙酯、己酸/己酸乙酯、丁酸/丁酸乙酯、乙醛/乙缩醛共6组风味成分... 以40个陶坛贮存的特香型白酒新基酒为研究对象,每3个月进行检测,跟踪检测2年。基于Pearson相关性分析,从化学反应平衡角度解析基酒总酸/总酯、乳酸/乳酸乙酯、乙酸/乙酸乙酯、己酸/己酸乙酯、丁酸/丁酸乙酯、乙醛/乙缩醛共6组风味成分在贮存期的相互平衡过程,同时通过配制平衡前后的模拟酒样,分析平衡对基酒感官风味的影响。结果表明,新酒酸酯比值各异,但在贮存过程中差异逐渐变小,酸与对应乙酯的线性相关系数(R2)不断增大,贮存2年相关系数(R2)可达到0.9以上,酸酯比值接近同一数值,达到化学反应平衡。贮存2年白酒酯化浓度商减小量与新酒浓度商具有极显著的正相关性(P<0.01),表明新酒酸酯比值与平衡比值相差越大,平衡速度越快。乙醛与乙缩醛在贮存过程中同步增长,始终保持良好的线性关系。风味成分化学平衡作用可提升酒体的闻香、绵甜感、醇厚感与爽净度。特香型基酒陶坛贮存2年主要风味成分可达到平衡。 展开更多
关键词 白酒 老熟 风味成分 变化规律 酸酯平衡
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扇形段拉矫力数据突变特征提取方法
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作者 代超 容芷君 +3 位作者 但斌斌 都胜朝 刘洋 肖浩 《计算机集成制造系统》 北大核心 2025年第1期254-263,共10页
多维时序拉矫力的幅值突变表征着扇形段机组的故障,多维时序数据的时间和空间复杂度对突变特征提取方法的准确率和效率提出了更高的要求。利用多维时序数据的时间和空间相似性,提出小波相关滤波结合主成分分析的多维时序突变特征提取方... 多维时序拉矫力的幅值突变表征着扇形段机组的故障,多维时序数据的时间和空间复杂度对突变特征提取方法的准确率和效率提出了更高的要求。利用多维时序数据的时间和空间相似性,提出小波相关滤波结合主成分分析的多维时序突变特征提取方法。首先,将每一维时域含噪拉矫力分别变换到小波域,利用拉矫力的自相似性进行降噪;然后,将去噪后的拉矫力映射到正交空间中,利用多维拉矫力之间的互相似性,通过线性变换将多维拉矫力映射到一维,再根据一维特征曲线的统计特征确定阈值,提取突变特征;最后,应用基于时间的滑动窗口动态更新数据,实现状态的连续在线识别;通过现场实测数据分析表明,小波相关滤波-主成分分析模型对多维时序数据的突变特征提取的准确率和效率分别达到90.39%和97.56%。 展开更多
关键词 扇形段 多维时间序列 主成分分析 突变特征
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不同地理分布水松叶挥发性成分差异
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作者 杨晓娟 刘世男 +3 位作者 邓必玉 卢志海 黄安书 梁永延 《热带作物学报》 北大核心 2025年第2期440-446,共7页
为探究水松(Glyptostrobus pensilis)叶挥发性成分的地理变化规律,本研究采用GC-MS方法测定广西6个地理分布(宾阳县、天等县、雁山区、苍梧县、平乐县和覃塘区)的野生水松叶挥发物成分。结果表明:不同地理分布水松叶挥发性成分共检测出... 为探究水松(Glyptostrobus pensilis)叶挥发性成分的地理变化规律,本研究采用GC-MS方法测定广西6个地理分布(宾阳县、天等县、雁山区、苍梧县、平乐县和覃塘区)的野生水松叶挥发物成分。结果表明:不同地理分布水松叶挥发性成分共检测出139种化学成分,其中,萜烯类的α-蒎烯和D-柠檬烯在各地理分布中的相对含量均较高,分别为18.61%~28.32%、16.80%~49.02%。通过对比6个地理分布水松叶挥发性成分发现,覃塘区水松叶挥发物种类最少,宾阳县的最多;雁山区的醇类、芳香烃类、醚类、醛类、萜烯类、酮类和酯类相对含量均最低,而天等县的芳香烃类、酚类、醚类、醛类、酸类、萜烯类和烷烃类相对含量均最高。不同地理分布水松叶挥发性成分主成分分析表明,前3个主成分累计贡献率达97.53%,可以反映大部分成分信息,其中,醚类、萜烯类、烷烃类、芳香烃类、酸类、烯烃类、酚类、酯类、酮类、醇类和其他类的特征向量绝对值较大,是区分不同地理分布水松的差异性物质。聚类分析结果显示,覃塘区、苍梧县和雁山区聚为一组,平乐县和宾阳县聚为一组,天等县单独为一组。挥发性成分与环境因子的相关性分析表明,经度和海拔对挥发性成分含量的影响最大。本研究结果可为水松的培育和资源利用提供参考依据。 展开更多
关键词 水松 挥发性成分 GC-MS 地理变化
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滇中4种典型公益林土壤活性有机碳分布特征
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作者 吴思政 李小英 +2 位作者 王毅雯 陈晓琴 朱腾达 《中南林业科技大学学报》 北大核心 2025年第2期185-193,215,共10页
【目的】云南省阔叶林面积远低于针叶林,阔叶林的生态功能没有得到充分重视,因此探究滇中地区不同公益林土壤活性有机碳空间分布特征和碳储量,为西南山地森林土壤碳汇管理以及生态效益评估提供参考依据。【方法】以滇中地区4种主要林分... 【目的】云南省阔叶林面积远低于针叶林,阔叶林的生态功能没有得到充分重视,因此探究滇中地区不同公益林土壤活性有机碳空间分布特征和碳储量,为西南山地森林土壤碳汇管理以及生态效益评估提供参考依据。【方法】以滇中地区4种主要林分(旱冬瓜、元江栲、锥连栎和云南松)为研究对象,分析土壤有机碳、DOC、ROC、MBC含量和碳储量在不同坡向0~60 cm土层的分布状况,以及土壤活性有机碳与土壤基本性质之间的相互影响。【结果】1)研究区3种阔叶树种土壤活性有机碳含量、碳储量在不同坡向上表现为阴坡>阳坡;土壤活性有机碳含量、碳储量具有明显的表聚现象,均随土层加深呈下降趋势;2)元江栲林各坡向0~20 cm土层的SOC、DOC和MBC含量显著高于其余3种林分(P<0.05),而ROC含量均值的最大值则出现在旱冬瓜林;3)4种林分土壤碳储量阴坡为116.37~327.10 t·hm^(-2),阳坡为97.49~263.81 t·hm^(-2),元江栲林固碳能力最佳,营造人工林或碳汇林可适当考虑增加该树种;4)4种林分SOC与DOC、ROC、MBC两两之间均呈正相关,3种阔叶林土壤活性有机碳含量与TP呈显著正相关(P<0.05),在今后森林培育过程中可补充磷肥以促进其生长发育。【结论】滇中地区土壤活性有机碳分布受树种影响显著,研究区内元江栲林土壤固碳能力最佳,今后建设碳汇林或公益林时可优先考虑选择阔叶树种元江栲。 展开更多
关键词 土壤 碳组分 碳储量 垂直变化 公益林
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