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NDVI changes in China between 1989 and 1999 using change vector analysis based on time series data 被引量:3
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作者 Chen Yun-hao Li Xiao-bing Xie Feng 《Journal of Geographical Sciences》 SCIE CSCD 2001年第4期3-12,共10页
Change vector analysis (CVA) and principal component analysis in NDVI time-trajectories space are powerful tools to analyze land-cover change. The magnitude of the change vector indicates amplitude of the change, whil... Change vector analysis (CVA) and principal component analysis in NDVI time-trajectories space are powerful tools to analyze land-cover change. The magnitude of the change vector indicates amplitude of the change, while its direction indicates the nature of the change. CVA is applied to two remotely sensed indicators of land surface conditions, NDVI and spatial structure, in order to improve the capability to detect and categorize land-cover change. The magnitude and type of changes are calculated in China from 1989 to 1999. Through the research, the main conclusions are drawn as follows: 1) The changes of NDVI are quite different between eastern China and western China, and the change range in the east is bigger than that in the west. The trend in NDVI time series is smoothly increasing, the increases happen mostly in Taiwan, Fujian, Sichuan and Henan provinces and the decreases occur in Yunnan and Xinjiang. 2) The spatial structure index can indicate changes in the seasonal ecosystem dynamics for spatially heterogeneous landscapes. Most of spatial structure changes, which occurred in southern China, correlated with vegetation growth processes and strike of mountains. 展开更多
关键词 LAND-COVER NDVI change vector analysis spatial structure
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Response of fuzzy clustering on different threshold determination algorithms in spectral change vector analysis over Western Himalaya, India 被引量:2
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作者 SINGH Sartajvir TALWAR Rajneesh 《Journal of Mountain Science》 SCIE CSCD 2017年第7期1391-1404,共14页
Abstract: Change detection is a standard tool to extract and analyze the earth's surface features from remotely sensed data. Among the different change detection techniques, change vector analysis (CVA) have an ex... Abstract: Change detection is a standard tool to extract and analyze the earth's surface features from remotely sensed data. Among the different change detection techniques, change vector analysis (CVA) have an exceptional advantage of discriminating change in terms of change magnitude and vector direction from multispectral bands. The estimation of precise threshold is one of the most crucial task in CVA to separate the change pixels from unchanged pixels because overall assessment of change detection method is highly dependent on selected threshold value. In recent years, integration of fuzzy clustering and remotely sensed data have become appropriate and realistic choice for change detection applications. The novelty of the proposed model lies within use of fuzzy maximum likelihood classification (FMLC) as fuzzy clustering in CVA. The FMLC based CVA is implemented using diverse threshold determination algorithms such as double-window flexible pace search (DFPS), interactive trial and error (T&E), and 3x3-pixel kernel window (PKW). Unlike existing CVA techniques, addition of fuzzy clustering in CVA permits each pixel to have multiple class categories and offers ease in threshold determination process. In present work, the comparative analysis has highlighted the performance of FMLC based CVA overimproved SCVA both in terms of accuracy assessment and operational complexity. Among all the examined threshold searching algorithms, FMLC based CVA using DFPS algorithm is found to be the most efficient method. 展开更多
关键词 Change vector analysis (CVA) Fuzzymaximum likelihood classification (FMLC) Double-window flexible pace search (DFPS) Interactive trialand error (T&E) Pixel kernel window (PKW)
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Bioelectrical impedance vector analysis evaluates cellularity and hydration in cirrhotic patients 被引量:1
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作者 Sabrina Alves Fernandes Lara Rigon Leonhardt +2 位作者 Daniella Miranda da Silva Fernanda Donner Alves Claudio Augusto Marroni 《World Journal of Hepatology》 2020年第12期1276-1288,共13页
BACKGROUND Malnutrition in cirrhotic patients is correlated with mortality and a better response to liver transplantation.However,recovery of the nutritional status in these patients is a challenge due to the difficul... BACKGROUND Malnutrition in cirrhotic patients is correlated with mortality and a better response to liver transplantation.However,recovery of the nutritional status in these patients is a challenge due to the difficulty in establishing a reliable nutritional diagnosis.The bioelectrical impedance vector analysis(BIVA)method appears as a feasible tool in clinical practice to define the physiological state of cirrhotic patients by assessing hydration and body cellularity.AIM To evaluate body composition in cirrhotic patients using BIVA.METHODS This retrospective cross-sectional study was carried out by following cirrhotic outpatients at a hospital in Porto Alegre,Brazil.A tetrapolar bioelectrical impedance analysis device was used to evaluate cellularity and hydration and to perform the BIVA.The BIVA graphic was elaborated by software and for statistical analysis a significance level of 5%(P≤0.05)was considered.RESULTS One hundred and ninety patients,61.1%males,with a mean age of 56.6±11.0 years,were evaluated.Of these,56.3%had Child-Turcotte-Pugh(CTP)A score,and the prevalent etiology was hepatitis C virus(47.4%).The patients were classified according to cellularity and hydration by the quadrants and ellipses of the BIVA method,quadrant 1(47.9%);quadrant 2(18.9%);quadrant 3(14.2%);and quadrant 4(18.9%).Those classified in quadrant 1 and 2 had a higher phase angle compared to those in quadrants 3 and 4(P<0.001).Quadrant 2 patients had a lower average age than the other groups.The association with CTP score showed that patients in quadrant 2 had a higher proportion of CTP A,and those in quadrant 4 had a higher proportion of CTP C(P<0.052).CONCLUSION The BIVA method allows identification of the cellularity and hydration status of cirrhotic patients,and its association with clinical factors determines the disease severity,age and prognostic index. 展开更多
关键词 Body composition HYDRATION CELLULARITY Hepatic cirrhosis Electrical Bioimpedance Bioelectrical impedance vector analysis
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Independent Vector Analysis Based Blind Interference Reduction and Signal Recovery for MIMO IoT Green Communications
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作者 Zhongqiang Luo Mingchun Li Chengjie Li 《China Communications》 SCIE CSCD 2022年第7期79-88,共10页
In application to time convolutive mixing model or frequency domain blind separation model for wireless receiving applications,frequency domain independent component analysis(FDICA)has been a very popular method but w... In application to time convolutive mixing model or frequency domain blind separation model for wireless receiving applications,frequency domain independent component analysis(FDICA)has been a very popular method but with adverse random permutation ambiguity influence.In order to solve this inherent problem in FDICA assisted multiple-input multiple-output orthogonal frequency-division multiplexing(MIMO-OFDM)based the Internet of Thing(IoT)systems,this paper proposes an new detection mechanism,named independent vector analysis(IVA),for realizing blind adaptive signal recovery in MIMO IoT green communication to reduce inter-carrier interference(ICI)and multiple access interference(MAI).IVA jointly implements separation work for different frequency bin data while the FDICA deals with it separately.In IVA,the dependencies of frequency bins can be exploited in mitigating the random permutation problem.In addition,multivariate prior distributions are employed to preserve the inter-frequency dependencies for individual sources,which can result in separation performance enhancement.Simulation results and analysis corroborate the effectiveness of the proposed method. 展开更多
关键词 independent vector analysis blind source separation MIMO green communications
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Vector analysis of Contoura Vision for the correction of myopia and myopic astigmatism
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作者 Ying Lin Huan-Jun Su +1 位作者 Mu-Zhi Yuan Yong Zhang 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2022年第6期983-989,共7页
AIM: To evaluate the visual outcomes of Contoura Vision(CV) with automatic eye tracking system in eyes with myopia and myopic astigmatism.METHODS: This prospective study included 160 eyes(80 patients) with moderate my... AIM: To evaluate the visual outcomes of Contoura Vision(CV) with automatic eye tracking system in eyes with myopia and myopic astigmatism.METHODS: This prospective study included 160 eyes(80 patients) with moderate myopia and irregular astigmatism between January and August 2018. Subjects were randomly divided into CV group(80 eyes) that under went CV femtosecond laser-assisted in situ keratomileusis(FS-LASIK) and a control group(80 eyes) that underwent wavefrontoptimized FS-LASIK. Visual outcomes and astigmatic vector analysis were evaluated and compared between preoperatively and 3 mo postoperatively. RESULTS: Basic details were similar in both groups(P>0.05). At 3 mo postoperatively, uncorrected distance visual acuity was 20/16, 20/20, and 20/25 in 24, 76, and 80 eyes of patients in CV group, respectively. The CV group was better in predictability of astigmatism correction at 3 mo postoperatively. In CV group, 64 eyes had deviation of astigmatic axis within 15° and 28 eyes had deviation of astigmatic axis within 5°, both were better than those in the control group. The number of eyes with residual astigmatism within 0.5 D were less in CV group(48 eyes) than the control group(40 eyes). Compared with the preoperative, C7 significantly reduced to 0.056±0.030 in CV group at 3 mo after the procedure(P<0.05), and were significantly lower than those in the control group(P<0.05).CONCLUSION: CV with automatic eye tracking system is safe and effective for the correction of myopia and myopic astigmatism. 展开更多
关键词 vector analysis irregular astigmatism Contoura Vision
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Q Vector Analysis of Torrential Rainfall from Meiyu Front Cyclone:A Case Study 被引量:1
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作者 岳彩军 《Acta meteorologica Sinica》 SCIE 2009年第1期68-80,共13页
Following similar derivation of quasi-geostrophic Q vector (Q^C), a new Q vector (Q^N) is constructed in this study. Their difference is that the geostrophic wind in quasi-geostrophic Q vector is replaced by the w... Following similar derivation of quasi-geostrophic Q vector (Q^C), a new Q vector (Q^N) is constructed in this study. Their difference is that the geostrophic wind in quasi-geostrophic Q vector is replaced by the wind in Q^N vector. The diagnostic analysis of Q^N vector is compared with that of Q^G vector in the case study of a typical Meiyu front cyclone (MYFC) occurred over Changjiang-Huaihe regions during 5-6 July 1991. The results show that the Q^N vector has more diagnostic advantages than Q^G vector does. Convergence of Q^N vector at 700 hPa is found to be a good indicator to mimic the horizontal distribution of precipitation. Q^N vector is further partitioned into four components: Q^Nalst (along-stream stretching),Q^Ncurv (curvature),Q^Nshdv (shear advection), and Q^Ncrst (cross-stream stretching) in a natural coordinate system with isohypse (PG partitioning). The application of Q^N PG partitioning in the MYFC torrential rain indicates that PG partitioning of Q can identify dominant physical processes. The horizontal distribution of 2V·Q^Nalst is similar to that of 2V·Q^N and mainly accounts for 2V·Q^N during the entire period of Meiyu. The effects of Q^Ncurv on rainfall enhancement fade from the mature stage to decay stage. Qshdv enhances precipitation significantly as the MYFC develops, and the effect weakens rapidly when the MYFC decays during its eastward propagation. Q^Ncrst shows little impacts on rainfall during the onset and mature phases whereas it displays significant role during the decay phase.Q^N alst and Q^Nshdv and Q^Ncrst show cancellation only during the decay period. 展开更多
关键词 Q vector analysis Q^N vector partitioning of Q^N vector Meiyu front cyclone torrential rainfall
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Surgically induced astigmatismCorneal astigmatismMeanSummated vector meanCentroidVector analysisTemporal incisionSuperior incisionICL implantation
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作者 Kazutaka Kamiya Wakako Ando +1 位作者 Masahide Takahashi Nobuyuki Shoji 《Eye and Vision》 SCIE CSCD 2023年第6期1-7,共7页
BackgroundTo compare the arithmetic mean (M-SIA) and the summated vector mean of surgically induced astigmatism (SVM-SIA) according to the incision site after phakic intraocular lens (Visian implantable collamer lens ... BackgroundTo compare the arithmetic mean (M-SIA) and the summated vector mean of surgically induced astigmatism (SVM-SIA) according to the incision site after phakic intraocular lens (Visian implantable collamer lens (ICL), STAAR Surgical) implantation.MethodsThis study comprised 121 eyes of 121 consecutive patients undergoing ICL surgery through a 3.0-mm temporal or superior clear corneal incision. The magnitude and the axis of corneal astigmatism preoperatively and 3 months postoperatively were measured using an automated keratometer. The M-SIA and the SVM-SIA were determined according to the incision site.ResultsThe magnitude of corneal astigmatism significantly increased from 1.23 ± 0.59 D preoperatively to 1.46 ± 0.72 D postoperatively in the temporal incision group (Wilcoxon signed-rank test, P < 0.001), but it significantly decreased from 1.09 ± 0.36 D preoperatively to 0.86 ± 0.41 D postoperatively in the superior incision group (P < 0.001). The M-SIA was 0.48 ± 0.30 D, and the SVM-SIA was 0.23 ± 0.52 D at a meridian of 82° in the temporal incision group. The M-SIA was 0.57 ± 0.30 D, and the SVM-SIA was 0.47 ± 0.45 D at a meridian of 1° in the superior incision group.ConclusionsICL implantation induces the M-SIA by approximately 0.5 D, but the SVM-SIA decreased to 50% and 80% of the M-SIA in magnitude through temporal and superior incisions, respectively. The direction of the SVM-SIA showed a tendency toward corneal flattening to the incisional site. It should be noted that the M-SIA is somewhat different from the SVM-SIA according to the incision site. 展开更多
关键词 Surgically induced astigmatism Corneal astigmatism Mean Summated vector mean CENTROID vector analysis Temporal incision Superior incision ICL implantation
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Slope stability analysis under seismic load by vector sum analysis method 被引量:15
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作者 Mingwei Guo Xiurun Ge Shuilin Wang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE 2011年第3期282-288,共7页
The vibration characteristics and dynamic responses of rock and soil under seismic load can be estimated with dynamic finite element method (DFEM). Combining with the DFEM, the vector sum analysis method (VSAM) is... The vibration characteristics and dynamic responses of rock and soil under seismic load can be estimated with dynamic finite element method (DFEM). Combining with the DFEM, the vector sum analysis method (VSAM) is employed in seismic stability analysis of a slope in this paper. Different from other conventional methods, the VSAM is proposed based on the vector characteristic of force and current stress state of the slope. The dynamic stress state of the slope at any moment under seismic load can he obtained by the DFEM, thus the factor of safety of the slope at any moment during earthquake can be easily obtained with the VSAM in consideration of the DFEM. Then, the global stability of the slope can be estimated on the basis of time-history curve of factor of safety and reliability theory. The VSAM is applied to a homogeneous slope under seismic load. The factor of safety of the slope is 1.30 under gravity only and the dynamic factor of safety under seismic load is 1.21. The calculating results show that the dynamic characteristics and stability state of the slope with input ground motion can be actually analyzed. It is believed that the VSAM is a feasible and practical approach to estimate the dynamic stability of slopes under seismic load. 展开更多
关键词 slope stability vector sum analysis method (VSAM) seismic load dynamic finite element method (DFEM)
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WAVELET ANALYSIS OF THE VECTOR MAGNITUDE WAVE FOR DETECTION OF VENTRICULAR LATE POTENTIALS
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作者 Wu shuicai Lin lan Lin Jiarui(Huazhong University of Science and technology, Wuhan 430074, China) 《Chinese Journal of Biomedical Engineering(English Edition)》 1999年第3期30-31,共2页
关键词 IEEE WAVELET analysis OF THE vector MAGNITUDE WAVE FOR DETECTION OF VENTRICULAR LATE POTENTIALS
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Fuzzy Random Reliability Analysis of Blocky Rock-Mass in Slopes 被引量:3
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作者 YANGKun ZHANGXin 《Journal of China University of Mining and Technology》 EI 2005年第2期129-134,共6页
Slope stability assessment is a geotechnical problem characterized by many sources of uncertainty. In clas- sical reliability analysis, only the randomness of uncertainties is taken into account but the fuzziness of t... Slope stability assessment is a geotechnical problem characterized by many sources of uncertainty. In clas- sical reliability analysis, only the randomness of uncertainties is taken into account but the fuzziness of them is ignored. In this paper, a fuzzy probability approach and a fuzzy JC method are presented for the reliability analysis. The two methods have been applied to stability analysis of a certain slope of permanent ship lock in the Three-Gorges Project. The results obtained from these two methods are basically the same. However, compared with the fuzzy probability means, the fuzzy JC method can reflect the real situation better because it uses a fuzzy-based analysis applied to not only limit state equation but also mechanical parameters. 展开更多
关键词 blocky rock mass vector analysis fuzzy-random reliability fuzzy failure probability
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LS-SVM and Monte Carlo methods based reliability analysis for settlement of soft clayey foundation 被引量:5
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作者 Yinghe Wang Xinyi Zhao Baotian Wang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2013年第4期312-317,共6页
A method which adopts the combination of least squares support vector machine(LS-SVM) and Monte Carlo(MC) simulation is used to calculate the foundation settlement reliability.When using LS-SVM,choosing the traini... A method which adopts the combination of least squares support vector machine(LS-SVM) and Monte Carlo(MC) simulation is used to calculate the foundation settlement reliability.When using LS-SVM,choosing the training dataset and the values for LS-SVM parameters is the key.In a representative sense,the orthogonal experimental design with four factors and five levels is used to choose the inputs of the training dataset,and the outputs are calculated by using fast Lagrangian analysis continua(FLAC).The decimal ant colony algorithm(DACA) is also used to determine the parameters.Calculation results show that the values of the two parameters,and δ2 have great effect on the performance of LS-SVM.After the training of LS-SVM,the inputs are sampled according to the probabilistic distribution,and the outputs are predicted with the trained LS-SVM,thus the reliability analysis can be performed by the MC method.A program compiled by Matlab is employed to calculate its reliability.Results show that the method of combining LS-SVM and MC simulation is applicable to the reliability analysis of soft foundation settlement. 展开更多
关键词 Foundation settlement Reliability analysis Least squares support vector machine(LS-SVM) Monte Carlo(MC) simulation Decimal ant colony algorithm(DACA)
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Modified Lorentz Transformations and Space-Time Splitting According to the Inverse Relativity Model
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作者 Michael Girgis 《Journal of Applied Mathematics and Physics》 2024年第7期2467-2489,共23页
Analysis of a four-dimensional displacement vector on the fabric of space-time in the special or general case into two Four-dimensional vectors, according to specific conditions leads to the splitting of the total fab... Analysis of a four-dimensional displacement vector on the fabric of space-time in the special or general case into two Four-dimensional vectors, according to specific conditions leads to the splitting of the total fabric of space-time into a positive subspace-time that represents the space of causality and a negative subspace-time which represents a space without causality, thus, in the special case, we have new transformations for the coordinates of space and time modified from Lorentz transformations specific to each subspace, where the contraction of length disappears and the speed of light is no longer a universal constant. In the general case, we have new types of matric tensor, one for positive subspace-time and the other for negative subspace-time. We also find that the speed of the photon decreases in positive subspace-time until it reaches zero and increases in negative subspace-time until it reaches the speed of light when the photon reaches the Schwarzschild radius. 展开更多
关键词 Four-Dimensional vector analysis Four-Dimensional Subspace Causal Space analysis of the Speed of Light Inverse Theory of Relativity
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Relativistic Mechanics in Positive and Negative Subspace-Time according to the Inverse Relativity Model
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作者 Michael Girgis 《Journal of Applied Mathematics and Physics》 2024年第11期3784-3815,共32页
In the second paper on the inverse relativity model, we explained in the first paper [1] that analyzing the four-dimensional displacement vector on space-time according to a certain approach leads to the splitting of ... In the second paper on the inverse relativity model, we explained in the first paper [1] that analyzing the four-dimensional displacement vector on space-time according to a certain approach leads to the splitting of space-time into positive and negative subspace-time. Here, in the second paper, we continue to analyze each of the four-dimensional vectors of velocity, acceleration, momentum, and forces on the total space-time fabric. According to the approach followed in the first paper. As a result, in the special case, we obtain new transformations for each of the velocity, acceleration, momentum, energy, and forces specific to each subspace-time, which are subject to the positive and negative modified Lorentz transformations described in the first paper. According to these transformations, momentum remains a conserved quantity in the positive subspace and increases in the negative subspace, while the relativistic total energy decreases in the positive subspace and increases in the negative subspace. In the general case, we also have new types of energy-momentum tensor, one for positive subspace-time and the other for negative subspace-time, where the energy density decreases in positive subspace-time and increases in negative subspace-time, and we also obtain new gravitational field equations for each subspace-time. 展开更多
关键词 4D Velocity vector analysis Positive Subspace Negative Subspace Negative Relativistic Mechanics Positive Tensor of Energy and Momentum Inverse Theory of Relativity
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Growth and nutrient dynamics of Betula alnoides seedlings under exponential fertilization 被引量:17
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作者 Lin Chen Chunsheng Wang +4 位作者 Bernard Dell Zhigang Zhao Junjie Guo Daping Xu Jie Zeng 《Journal of Forestry Research》 SCIE CAS CSCD 2018年第1期111-119,共9页
Betula alnoides is a fast-growing hardwood species grown in large plantations in Southeast Asia and South China.Nitrogen requirements for producing robus seedlings,growth and nutrient dynamics were investigated using ... Betula alnoides is a fast-growing hardwood species grown in large plantations in Southeast Asia and South China.Nitrogen requirements for producing robus seedlings,growth and nutrient dynamics were investigated using exponential fertilization treatments.Root collar diameter,height,dry mass and nutrient contents of seedlings increased exponentially in all fertilization treatments as time progressed.Moreover,with water soluble fertilizer(Plant Products plus microelements N–P2O5–K2O:20–20–20),300 mg N seedling-1was adequate.Vector analysis revealed that P was the most responsive nutrient element followed by N and K.Dilutions of N and K were evident in the plants without N addition,which induced initial P sufficiency and then luxury consumption probably due to the antagonistic interaction between N and P.However deficiencies of N,P and K were mostly observed in al exponential regimes during the experiment because seedling growth rate exceeded nutrient uptake rate,inferring that further study on improving the nutrient uptake efficiency is needed.Analysis of relationships among nutrient supply,dry mass,N content and N concentration demonstrated that 100–400 mg N seedling-1induced sufficiency to luxury consumption of nitrogen without significant change in dry mass,and 400 mg N seedling-1is recommended to apply for nutrient loading of seedlings before outplanting.The findings will help improve seedling quality and enhance the production of robust seedlings for plantation forestry of this species. 展开更多
关键词 Betula alnoides Growth performance Luxury nutrient consumption Nitrogen requirement vector analysis
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GRINDING OF DOUBLE DISC GRINDING MACHINE 被引量:4
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作者 HuHuiqing 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2005年第1期1-4,共4页
The grinding of two parallel sides of a component is accomplished with theaccuracy and higher productivity by passing a blank through the truncated cone shape grinders, whichare turned angles. The machine is designate... The grinding of two parallel sides of a component is accomplished with theaccuracy and higher productivity by passing a blank through the truncated cone shape grinders, whichare turned angles. The machine is designated by the name of double disc grinding machine (DDGM).Usually, it is used in the mass production. The relationship between these angles, the accuracy,productivity, allowance and parameters of the machine and technology is explained in detail by math,such as vector analysis, transformation of 3D space coordinates, etc. Therefore, in the aspects ofqualitative and quantitative analyses, the grinding potential of DDGM is enormous increased andsuperior to conventional methods. Furthermore, the theoretical foundation of DDGM grinding designand technology is provided to improve, to expand and to create for future. The established machinedesign and practical experience of grinding technology will get great benefit by them. 展开更多
关键词 Truncated cone shape vector analysis Qualitative and quantitative analysis
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Using multispectral landsat and sentinel-2 satellite data to investigate vegetation change at Mount St. Helens since the great volcanic eruption in 1980 被引量:2
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作者 Katharina TELTSCHER Fabian Ewald FASSNACHT 《Journal of Mountain Science》 SCIE CSCD 2018年第9期1851-1867,共17页
Long-term analyses of vegetation succession after catastrophic events are of high interest for an improved understanding of succession dynamics. However, in many studies such analyses were restricted to plot-based mea... Long-term analyses of vegetation succession after catastrophic events are of high interest for an improved understanding of succession dynamics. However, in many studies such analyses were restricted to plot-based measurements. Contrarily, spatially continuous observations of succession dynamics over extended areas and timeperiods are sparse. Here, we applied a change vector analysis(CVA) to investigate vegetation succession dynamics at Mount St. Helens after the great volcanic eruption in 1980 using Landsat. We additionally applied a supervised random forest classification using Sentinel-2 data to map the currently prevailing vegetation types. Change vector analysis was performed with the normalized difference vegetation index(NDVI) and the urban index(UI) for three subsequent decades after the eruption as well as for the whole observation time between 1984 and 2016. The influence of topography on the current vegetation distribution was examined by comparing altitude, slope angles and aspect values of vegetation classes derived by the random forest classification. WilcoxRank-Sum test was applied to test for significant differences between topographic properties of the vegetation classes inside and outside of the areas affected by the eruption. For the full time period, a total area of 516 km2 was identified as re-vegetated, whereas the area and magnitude of re-growing vegetation decreased during the three decades and migrated closer to the volcanic crater. Vegetation losses were mainly observed in regions unaffected by the eruption and related mostly to timber harvesting. The vegetation type classification reached a high overall accuracy of approximately 90%. 36 years after the eruption, coniferous and deciduous trees have established at formerly devastated areas dominating with a proportion of 66%, whereas shrubs are more abundant in riparian zones. Sparse vegetation dominates at regions very close to the crater. Elevation was found to have a great influence on the reestablishment and distribution of the vegetation classes within the devastated areas showing in almost all cases significant differences in altitude distribution. Slope was less important for the different classes-only representing significantly higher values for meadows, whereas aspect seems to have no notable influence on the reestablishment of vegetation at Mount St. Helens. We conclude that major vegetation succession dynamics after catastrophic events can be assessed and characterized over large areas from freely available remote sensing data and hence contribute to an improved understanding of succession dynamics. 展开更多
关键词 Mount St. Helens Vegetation change Remote sensing Change vector analysis (CVA) Supervised classification Topography Density-plots
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Single-step transepithelial photorefractive keratectomy in high myopia:qualitative and quantitative visual functions 被引量:8
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作者 Soheil Adib-Moghaddam 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2017年第3期445-452,共8页
AIM:To investigate quantitative and qualitative optical outcomes of single-step transepithelial photorefractive keratectomy(Trans PRK)in high myopia.METHODS:In a prospective interventional case-series,30 eyes with... AIM:To investigate quantitative and qualitative optical outcomes of single-step transepithelial photorefractive keratectomy(Trans PRK)in high myopia.METHODS:In a prospective interventional case-series,30 eyes with high myopia(-6.00 to-8.75 D)with(up to-3.00 D)or without astigmatism were enrolled from Bina Eye Hospital,Tehran,Iran. One-step Trans PRK was performed with aberration-free aspherical optimized profile and SCHWIND AMARIS 500 laser. One-year follow-up results for refraction,visual acuities,vector analysis,ocular wavefront(OWF)and corneal wave-front(CWF)higher order aberrations(HOA),contrast sensitivity(CS),and postoperative haze were assessed.RESULTS:After the surgery,both photopic and mesopic CSs significantly improved(both P〈0.001). We detected significant induction of OWF coma and trefoil(P〈0.001 for both)HOAs; CWF coma(P=0.002),spherical(P〈0.001),and tetrafoil(P=0.003)HOAs in 6 mm analysis diameter; and CWF trefoil(P=0.04)HOA in 4 mm analysis diameter. The range of mean induction observed for various HOAs was0.005-0.11 μm. The 86.7% of eyes reached an uncorrected distance visual acuity of 20/20 or better; 96.7% of eyes were within ±0.5 D of targeted spherical refraction. In vector analysis,mean correction index value was 1.03 and mean index of success was 0.22. By 12mo after the operation,no eye lost any number of corrected distancevisual acuity lines. We detected no corneal haze greater than 1~+ throughout the follow-up.CONCLUSION:Our findings show promising effects of single-step Trans PRK on quality of vision in high myopic eyes. It also improves refraction and visual acuity. 展开更多
关键词 single-step transepithelial photorefractive keratectomy transepithelial photorefractive keratectomy high myopia contrast sensitivity higher order aberrations vector analysis
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Validity of automated refraction after segmented refractive multifocal intraocular lens implantation 被引量:5
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作者 Cesar Albarran-Diego Gonzalo Munoz +2 位作者 Stephanie Rohrweck Satiago Garcia-Lazaro Jose Ricardo Albero 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2017年第11期1728-1733,共6页
AIM: To evaluate the clinical utility of automated refraction(AR) and keratometry(KR) compared with subjective or manifest refraction(MR) after cataract or refractive lens exchange surgery with implantation of ... AIM: To evaluate the clinical utility of automated refraction(AR) and keratometry(KR) compared with subjective or manifest refraction(MR) after cataract or refractive lens exchange surgery with implantation of Lentis Mplus X(Oculentis GmbH) refractive multifocal intraocular lens(IOL).METHODS: Eighty-six eyes implanted with the Lentis Mplus X multifocal IOL were included. MR was performed in all patients followed by three consecutive AR measurements using the Topcon KR-8000 autorefractor. Assessment of repeatability of consecutive AR before and after dilation with phenylephrine 10%, and comparison of the AR and KR with MR using vector analysis were performed at 3 mo follow-up.RESULTS: Analysis showed excellent repeatability of the AR measurements. Linear regression of AR versus MR showed good correlation for sphere and spherical equivalent, whereas the correlation for astigmatism was low. The mean difference AR-MR was-1.28±0.29 diopters(D) for sphere. Astigmatism showed better correlation between KR and MR. CONCLUSION: We suggest AR sphere plus 1.25 D and the KR cylinder as the starting point for MR in eyes with a Lentis Mplus X multifocal IOL. If AR measurements are equal to MR, decentration of the IOL should be suspected. 展开更多
关键词 autorefraction vector analysis agreement multifocal intraocular lenses
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Nitrogen retranslocation, allocation, and utilization in bare root Larix olgensis seedlings
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作者 WEI Hong.xu·XU Cheng-yang · MA Lii-yi · DUAN Jie 《Journal of Forestry Research》 SCIE CAS CSCD 2012年第1期87-94,共8页
We quantified biomass accumulation and nitrogen (N) re- translocation, allocation, and utilization of Changbai larch (Larix olgen- sis) seedlings subjected to four fertilization treatments (24, 59, 81, 117 kg.ha-... We quantified biomass accumulation and nitrogen (N) re- translocation, allocation, and utilization of Changbai larch (Larix olgen- sis) seedlings subjected to four fertilization treatments (24, 59, 81, 117 kg.ha-1 N) with an unfertilized control during summer and autumn 2009. Ammonium phosphate (18-46-0) was the fertilizer used in all treatments. On both sampling dates, the needles had greater biomass and N content than new (2009) stems and old (2008) stems, and coarse, medium and fine roots (diameters of 〉5, 2-5 mm, and 0-2 mm, respectively). Higher N concentration was observed in old stems and coarse roots than that in new stems and medium roots. In mid-summer, fine roots had higher N concentration than coarse roots. The treatment with 24 kg.ha1 N had the greatest biomass and N content in needles and old stems, and highest net N retranslocation (NRA) and amount of N derived from soil. On Sep- tember 21, no N translocation was observed, while the treatment with 24 kg.ha^-1 N had the highest N utilization efficiency and fertilizer efficiency. Vector analysis revealed that all four fertilization treatments induced Nexcess relative to the control. The treatments with 59, 81, 117 kg.ha^-1 N induce N excess compared with treatments at 24 kg.ha-1 N. We conclude that the traditional local fertilizer application rates exceeded N require- ments and N uptake ability for Changbai larch seedlings. The application rate of 24 kg.ha^-1 N is recommended. 展开更多
关键词 Larix olgensis NITROGEN RETRANSLOCATION ALLOCATION bio-mass vector analysis
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Growth Responses of Trees to Micronutrients and Their Feedback Effect in Various Soil-Forest Ecosystems of Taihu Lake Region
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作者 ZHANGHUANCHAO XUHONGQIANG 《Pedosphere》 SCIE CAS CSCD 2001年第4期311-320,共10页
Vector analysis technique and ecological sequential comparison methods were adopted to study tree growth response to the micronutrients, B, Mo, Cu, Zn, Fe, and Mn, in soils derived from various parent materials in the... Vector analysis technique and ecological sequential comparison methods were adopted to study tree growth response to the micronutrients, B, Mo, Cu, Zn, Fe, and Mn, in soils derived from various parent materials in the forest area of Taihu Lake region in southeast China. The results showed that the dry weight of individual current-year needle of Chinese fir (Cunninghamia lanceolata) grown on the soi1 derived from granite parent rock was increased by 8% and 13% in comparison with that grown on the soils derived from sandstone and ash-tuff parent rock, respectively. And such dry weight of loblolly pine (Pinus taeda) grown on the soil derived from sandstone parent rock was increased by 21% in comparison with that on the soil derived from ash-tuff parent rock. One of the reasons for those results was that micronutrients content in the soil derived from ash-tuff parent rock were not sufficient to meet the requirement of the growth of Chinese fir and loblolly pine, i.e., micronutrients in soil were deficient and/or induced deficient. The amounts of Cu, Zn, Fe, and Mn uptake by Chinese fir and loblolly pine were in agreement with the contents of available micronutrients in soil respectively, except for B and Mo. Meanwhile, there might exist an "antagonism" between the uptake of B versus Mo by trees, although more studies are needed to confirm it. Regression analysis indicated that amount of a soil available micronutrient was correlated to the type of parent material and its total amount in the forest floor, except for B. The F test identified that the correlation of each equation reached the significant level to different extents, respectively. The t test confirmed that amount of available forms was mainly depended on the type of parent material for Mo, Cu, Zn and Mn but on the forest floor for Fe. There was a feedback effect of forest stand on the amount of soil available micronutrients. The ability of accumulating available micronutrients in soil was better by the sawtooth oak (Quercus acutissima) stand than by the Chinese fir stand (except for B). The ability of accumulating available Zn, Fe, Mn and Mo in soil was better by the Chinese fir stand than by the loblolly pine stand, while as for available B and Cu, by the latter was better than by the former. When discussing the effect of forest stand on the amount of soil available micronutrients, not only the amount of micronutrient in the forest floor and the parent materials but also the amount of micronutrient taken up by current-year needles have to be considered. 展开更多
关键词 feedback effect MICRONUTRIENT parent rock tree growth vector analysis
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