To obtain higher accurate position estimates, the stochastic model is estimated by using residual of observations, hence, the stochastic model describes the noise and bias in measurements more realistically. By using ...To obtain higher accurate position estimates, the stochastic model is estimated by using residual of observations, hence, the stochastic model describes the noise and bias in measurements more realistically. By using GPS data and broadcast ephemeris, the numerical results indicating the accurate position estimates at sub-meter level are obtainable.展开更多
Aims The Brazilian cerrado occupies land that could be occupied by seasonal forest,given current climatic conditions and their spatial proximity.Soil has been identified as one of the main determinants of cerrado and ...Aims The Brazilian cerrado occupies land that could be occupied by seasonal forest,given current climatic conditions and their spatial proximity.Soil has been identified as one of the main determinants of cerrado and forest prevalence.We tested whether cerrado and seasonal forest woody floras were assembled by different processes.We postulated that soil nutrient availability would account for dif-ferences in the functional and phylogenetic structure of the cerrado and the seasonal forest.Methods In 1005×5 m plots distributed along cerrado and seasonal forest patches in south-eastern Brazil,we sampled five individuals with a basal diameter≥3 cm from 127 species and measured seven of their functional traits(plant height,basal area,tortuosity,leaf size,specific leaf area,leaf dry matter content,and leaf toughness).We constructed a phylogenetic tree and calculated the pairwise mean functional-phy-logenetic distances(MFPDs),an approach that accounts for functional and phylogenetic information both separately and combined.We also sampled soils to a depth of 5 cm in each plot and had their chem-ical and physical properties determined.We related the MFPD to soil properties and compared MFPD between cerrado and forest species.Important Findings Phylogenetic distances were higher than functional distances in both cerrado and seasonal forest communities,suggesting trait convergence in both environments.Irrespective of the importance given to functional or phylogenetic information,most of the com-munities in the cerrado and in the seasonal forest fell within the null expectation,implying either that multiple assembly processes can occur simultaneously along the gradient of soil fertility,or that not all important traits were included.MFPD was related to soil nutrient status when only functional distances were considered.In this case,MFPD was lower in the cerrado than in the forest,indi-cating that soil nutrient availability influenced plant traits,with the low-nutrient soils in the cerrado constraining the range of variat展开更多
This research addresses the design of intensity-curvature functional(ICF)based digital high pass filter(HPF).ICF is calculated from bivariate cubic B-spline model polynomial function and is called ICF-based HPF.In ord...This research addresses the design of intensity-curvature functional(ICF)based digital high pass filter(HPF).ICF is calculated from bivariate cubic B-spline model polynomial function and is called ICF-based HPF.In order to calculate ICF,the model function needs to be second order differentiable and to have non-null classic-curvature calculated at the origin(0,0)of the pixel coordinate system.The theoretical basis of this research is called intensitycurvature concept.The concept envisions to replace signal intensity with the product between signal intensity and sum of second order partial derivatives of the model function.Extrapolation of the concept in two-dimensions(2D)makes it possible to calculate the ICF of an image.Theoretical treatise is presented to demonstrate the hypothesis that ICF is HPF signal.Empirical evidence then validates the assumption and also extends the comparison between ICF-based HPF and ten different HPFs among which is traditional HPF and particle swarm optimization(PSO)based HPF.Through comparison of image space and k-space magnitude,results indicate that HPFs behave differently.Traditional HPF filtering and ICF-based filtering are superior to PSO-based filtering.Images filtered with traditional HPF are sharper than images filtered with ICF-based filter.The contribution of this research can be summarized as follows:(1)Math description of the constraints that ICF need to obey to in order to function as HPF;(2)Math of ICF-based HPF of bivariate cubic B-spline;(3)Image space comparisons between HPFs;(4)K-space magnitude comparisons between HPFs.This research provides confirmation on the math procedure to use in order to design 2D HPF from a model bivariate polynomial function.展开更多
基金Supported by the National 863 Program of China （No.2006AA12Z325） and the National Natural Science Foundation of China （No.40274005）.
文摘To obtain higher accurate position estimates, the stochastic model is estimated by using residual of observations, hence, the stochastic model describes the noise and bias in measurements more realistically. By using GPS data and broadcast ephemeris, the numerical results indicating the accurate position estimates at sub-meter level are obtainable.
基金We are grateful to São Paulo Research Foundation(FAPESP,grant 2012/18295-4)to Coordination for the Improvement of Higher Education Personnel(CAPES,grant BEX 12105/13-9)for the scholarships granted to the first author+7 种基金to the National Council for Scientific and Technological Development for financial support and scholarship granted to the second author(CNPq,grant 305912/2013-5)to São Paulo Forestry Institute,for research permissionto the Vaçununga State Park staff,for logistical assistanceto M Groppo and WM Mantovani,for helping us with species identificationto N Abe,ALS Albino,KR Coelho,P Dodonov,JR Freitas,CS Gonçalves,DT Gregolin,LA Joaquim,MB Leite,WB Nascimento,LV Nóbrega,BA Severian and CB Zanelli,for help with field workto JR Freitas for revising an earlier draft of this manuscriptto EF Gray for revising the latest version of this manuscriptto Wiley for permitting the repro-duction of Figure 1,and to G Sonnier and an anonymous reviewer for their comments.
文摘Aims The Brazilian cerrado occupies land that could be occupied by seasonal forest,given current climatic conditions and their spatial proximity.Soil has been identified as one of the main determinants of cerrado and forest prevalence.We tested whether cerrado and seasonal forest woody floras were assembled by different processes.We postulated that soil nutrient availability would account for dif-ferences in the functional and phylogenetic structure of the cerrado and the seasonal forest.Methods In 1005×5 m plots distributed along cerrado and seasonal forest patches in south-eastern Brazil,we sampled five individuals with a basal diameter≥3 cm from 127 species and measured seven of their functional traits(plant height,basal area,tortuosity,leaf size,specific leaf area,leaf dry matter content,and leaf toughness).We constructed a phylogenetic tree and calculated the pairwise mean functional-phy-logenetic distances(MFPDs),an approach that accounts for functional and phylogenetic information both separately and combined.We also sampled soils to a depth of 5 cm in each plot and had their chem-ical and physical properties determined.We related the MFPD to soil properties and compared MFPD between cerrado and forest species.Important Findings Phylogenetic distances were higher than functional distances in both cerrado and seasonal forest communities,suggesting trait convergence in both environments.Irrespective of the importance given to functional or phylogenetic information,most of the com-munities in the cerrado and in the seasonal forest fell within the null expectation,implying either that multiple assembly processes can occur simultaneously along the gradient of soil fertility,or that not all important traits were included.MFPD was related to soil nutrient status when only functional distances were considered.In this case,MFPD was lower in the cerrado than in the forest,indi-cating that soil nutrient availability influenced plant traits,with the low-nutrient soils in the cerrado constraining the range of variat
文摘This research addresses the design of intensity-curvature functional(ICF)based digital high pass filter(HPF).ICF is calculated from bivariate cubic B-spline model polynomial function and is called ICF-based HPF.In order to calculate ICF,the model function needs to be second order differentiable and to have non-null classic-curvature calculated at the origin(0,0)of the pixel coordinate system.The theoretical basis of this research is called intensitycurvature concept.The concept envisions to replace signal intensity with the product between signal intensity and sum of second order partial derivatives of the model function.Extrapolation of the concept in two-dimensions(2D)makes it possible to calculate the ICF of an image.Theoretical treatise is presented to demonstrate the hypothesis that ICF is HPF signal.Empirical evidence then validates the assumption and also extends the comparison between ICF-based HPF and ten different HPFs among which is traditional HPF and particle swarm optimization(PSO)based HPF.Through comparison of image space and k-space magnitude,results indicate that HPFs behave differently.Traditional HPF filtering and ICF-based filtering are superior to PSO-based filtering.Images filtered with traditional HPF are sharper than images filtered with ICF-based filter.The contribution of this research can be summarized as follows:(1)Math description of the constraints that ICF need to obey to in order to function as HPF;(2)Math of ICF-based HPF of bivariate cubic B-spline;(3)Image space comparisons between HPFs;(4)K-space magnitude comparisons between HPFs.This research provides confirmation on the math procedure to use in order to design 2D HPF from a model bivariate polynomial function.
