Minimax Testing of Nonparametric Hypotheses on a Distribution Density in the $L_p$ Metrics

1987 ◽  
Vol 31 (2) ◽  
pp. 333-337 ◽  
Author(s):  
Yu. I. Ingster
Keyword(s):  
Distribution Density ◽  
Minimax Testing

scholarly journals The Root-Soil Water Relationship Is Spatially Anisotropic in Shrub-Encroached Grassland in North China: Evidence from GPR Investigation

2021 ◽  
Vol 13 (6) ◽  
pp. 1137
Author(s):  
Xihong Cui ◽  
Zheng Zhang ◽  
Li Guo ◽  
Xinbo Liu ◽  
Zhenxian Quan ◽  
...  
Keyword(s):  
Soil Water ◽  
Root Distribution ◽  
Preferential Flow ◽  
Distribution Density ◽  
Vertical Direction ◽  
Additive Models ◽  
Depth Interval ◽  
Soil Core ◽  
Semi Arid ◽  
Free Area

To analyze the root-soil water relationship at the stand level, we integrated ground-penetrating radar (GPR), which characterized the distribution of lateral coarse roots (>2 mm in diameter) of shrubs (Caragana microphylla Lam.), with soil core sampling, which mapped soil water content (SWC) distribution. GPR surveys and soil sampling were carried out in two plots (Plot 1 in 2017 and Plot 2 in 2018) with the same size (30 × 30 m2) in the sandy soil of the semi-arid shrubland in northern China. First, the survey area was divided into five depth intervals, i.e., 0–20, 20–40, 40–60, 60–80, and 80–100 cm. Each depth interval was then divided into three zones in the horizontal direction, including root-rich canopy-covered area, root-rich canopy-free area, and root-poor area, to indicate different surface distances to the canopy. The generalized additive models (GAMs) were used to analyze the correlation between root distribution density and SWC after the spatial autocorrelation of each variable was eliminated. Results showed that the root-soil water relationship varies between the vertical and horizontal directions. Vertically, more roots are distributed in soil with high SWC and fewer roots in soil with low SWC. Namely, root distribution density is positively correlated with SWC in the vertical direction. Horizontally, the root-soil water relationship is, however, more complex. In the canopy-free area of Plot 1, the root-soil water relationship was significant (p < 0.05) and negatively correlated in the middle two depth intervals (20–40 cm and 40–60 cm). In the same two depth intervals in the canopy-free area of Plot 2, the root-soil water relationship was also significant (p < 0.01) but non-monotonic correlated, that is, with the root distribution density increasing, the mean SWC decreased first and then increased. Moreover, we discussed possible mechanisms, e.g., root water uptake, 3D root distribution, preferential flow along roots, and different growing stages, which might lead to the spatially anisotropic relationship between root distribution and SWC at the stand level. This study demonstrates the advantages of GPR in ecohydrology studies at the field scale that is challenging for traditional methods. Results reported here complement existing knowledge about the root-soil water relationship in semi-arid environments and shed new insights on modeling the complex ecohydrological processes in the root zone.

Effect of shape/size and distribution of microgeometries of textures on tribo-performance of crankpin bearing

2021 ◽  
pp. 135065012110105
Author(s):  
Nguyen Van Liem ◽  
Wu Zhenpeng ◽  
Jiao Renqiang
Keyword(s):  
Friction Coefficient ◽  
Friction Force ◽  
Contact Force ◽  
Distribution Density ◽  
Hydrodynamic Lubrication ◽  
Operating Conditions ◽  
Asperity Contact ◽  
Combined Model ◽  
Obvious Effect ◽  
Area Density

The effect of the shape/size and distribution of microgeometries of textures on improving the tribo-performance of crankpin bearing is proposed. Based on a combined model of the slider-crank mechanism dynamic and hydrodynamic lubrication, the distribution density, area density, and shape of spherical textures, square-cylindrical textures, wedge-shaped textures, and a hybrid between spherical texture and square-cylindrical texture on the crankpin bearing's tribo-performance are investigated under different operating conditions of the engine. The tribological characteristic of the crankpin bearing is then evaluated via the indexes of the oil film pressure p, asperity contact force, friction force, and friction coefficient of the crankpin bearing. The research results show that the distribution density with n = 12 and m = 6, and area density with α = 30% of various microtextures have an obvious effect on ameliorating the crankpin bearings tribo-performance. Concurrently, at the mixed lubrication region, the shape of the square-cylindrical texture on improving the tribo-performance is better than the other shapes of the spherical texture, wedge-shaped texture, and spherical and square-cylindrical texture. Particularly, all the average values of the asperity contact force, friction force, and friction coefficient with a square-cylindrical texture are significantly reduced by 14.6%, 19.5%, and 34.5%, respectively, in comparison without microtextures. Therefore, the microtextures of the spherical texture applied on the bearing surface can contribute to enhance the durability and decrease the friction power loss of the engine.

A distribution density-based methodology for driving data cluster analysis: A case study for an extended-range electric city bus

2018 ◽  
Vol 73 ◽  
pp. 131-143 ◽  
Author(s):  
Haiming Xie ◽  
Guangyu Tian ◽  
Hongxu Chen ◽  
Jing Wang ◽  
Yong Huang
Keyword(s):  
Cluster Analysis ◽  
Distribution Density ◽  
City Bus ◽  
Extended Range

Distance Density Based Clustering Algorithm in Wireless Sensor Network

2011 ◽  
Vol 291-294 ◽  
pp. 344-348
Author(s):  
Lin Lin ◽  
Shu Yan ◽  
Yi Nian
Keyword(s):  
Clustering Algorithm ◽  
Distribution Density ◽  
Simulation Experiment ◽  
Clustering Algorithms ◽  
Wireless Sensor ◽  
Energy Usage ◽  
Cluster Heads ◽  
Hierarchical Topology ◽  
Energy Factors ◽  
Density Based Clustering

The hierarchical topology of wireless sensor networks can effectively reduce the consumption in communication. Clustering algorithm is the foundation to realize herarchical structure, so it has been extensive researched. On the basis of Leach algorithm, a distance density based clustering algorithm (DDBC) is proposed, considering synthetically the distribution density of around nodes and the remaining energy factors of the node to dynamically banlance energy usage of nodes when selecting cluster heads. We analyzed the performance of DDBC through compared with the existing other clustering algorithms in simulation experiment. Results show that the proposed method can generare stable quantity cluster heads and banlance the energy load effectively.

scholarly journals Modeling light interception and distribution in mixed canopy of common cocklebur (Xanthium stramarium) in competition with corn

2010 ◽  
Vol 28 (3) ◽  
pp. 455-462 ◽  
Author(s):  
F. Vazin ◽  
M. Hassanzadeh ◽  
A. Madani ◽  
M. Nassiri-Mahallati ◽  
M. Nasri
Keyword(s):  
Leaf Area ◽  
Extinction Coefficient ◽  
Distribution Density ◽  
Yield Loss ◽  
Light Interception ◽  
Area Index ◽  
Corn Seed ◽  
Parabolic Function ◽  
Triangular Function ◽  
Height Model

The aim of this study was to model light interception and distribution in the mixed canopy of Common cocklebur (Xanthium stramarium) with corn. An experiment was conducted in factorial arrangement on the basis of randomized complete blocks design with three replications in Gonabad in 2006-2007 and 2007-2008 seasons. The factors used in this experiment include corn density of 7.5, 8.5 and 9.5 plants per meter of row and density of Common cocklebur of zero, 2, 4, 6 and 8 plants per meter of row. INTERCOM model was used through replacing parabolic function with triangular function of leaf area density. Vertical distribution of the species' leaf area showed that corn has concentrated the most leaf area in layer of 80 to 100 cm while Common cocklebur has concentrated in 35-50 cm of canopy height. Model sensitivity analysis showed that leaf area index, species' height, height where maximum leaf area is seen (hm), and extinction coefficient have influence on light interception rate of any species. In both species, the distribution density of leaf area at the canopy length fit a triangular function, and the height in which maximum leaf area was observed was changed by change in density. There was a correlation between percentage of the radiation absorbed by the weed and percentage of corn seed yield loss (r² = 0.89). Ideal type of corn was determined until the stage of tasseling in competition with weed. This determination indicates that the corn needs more height and leaf area, as well as less extinction coefficient to successfully fight against the weed.

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