Three‐dimensional soil heterogeneity modulates responses of grassland mesocosms to an experimentally imposed drought extreme

Oikos ◽  
2021 ◽  
Author(s):  
Yongjie Liu ◽  
Michiel F. Bortier ◽  
Ivan Nijs ◽  
Yongshuo Fu ◽  
Zhenqing Li ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Soil Heterogeneity

scholarly journals Three-dimensional modeling of nitrate-N transport in vadose zone: Roles of soil heterogeneity and groundwater flux

2018 ◽  
Vol 211 ◽  
pp. 15-25 ◽  
Author(s):  
Simin Akbariyeh ◽  
Shannon Bartelt-Hunt ◽  
Daniel Snow ◽  
Xu Li ◽  
Zhenghong Tang ◽  
...  
Keyword(s):  
Vadose Zone ◽  
Three Dimensional ◽  
Soil Heterogeneity ◽  
Three Dimensional Modeling ◽  
Groundwater Flux ◽  
Dimensional Modeling ◽  
Nitrate N

Effects of three-dimensional soil heterogeneity on seed germination in controlled experiments

2020 ◽  
Vol 14 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Yongjie Liu ◽  
Fujiang Hou
Keyword(s):  
Seed Germination ◽  
Germination Rate ◽  
Three Dimensional ◽  
Soil Heterogeneity ◽  
Strong Variation ◽  
Soil Resources ◽  
Soil Spatial Heterogeneity ◽  
Elymus Nutans ◽  
Negative Impacts ◽  
Growing Conditions

Abstract Aims Seed germinations react to their local growing conditions, but the impacts of soil heterogeneity on seed germinations are not well known. Methods Effects of three-dimensional soil heterogeneity on seed germinations of grasses species were explored, where two levels of such soil heterogeneity were created via alternatively filling nutrient-poor and nutrient-rich substrate in pot in all directions. Patch sizes of the two heterogeneity levels are around 7.5 and 15 cm, respectively. Fifty seeds of each of the grasses species (Lolium perenne and Elymus nutans) were set either in these heterogeneous soils or in petri dishes with distilled water. Seed germinations of these species were daily recorded. Important Findings We found that pots with smaller patches had relatively lower germination rate, which is consistent with our expectation that shorter distance between nutrient-rich and nutrient-poor patches in pots with smaller patches allows plants to reduce their germination rates and delay their germination, in order to reduce the negative impacts of the strong variation of soil resources in these pots. Our results also revealed that pots with smaller patches yielded more heterogeneous seed germination, i.e. seed germinations highly diverged among these pots. These findings highlight that the realistic three-dimensional design can improve our understanding of seed germination as driven by soil spatial heterogeneity.

scholarly journals Root distribution responses to three-dimensional soil heterogeneity in experimental mesocosms

2017 ◽  
Vol 421 (1-2) ◽  
pp. 353-366 ◽  
Author(s):  
Yongjie Liu ◽  
Michiel F. Bortier ◽  
Hans J. De Boeck ◽  
Ivan Nijs
Keyword(s):  
Root Distribution ◽  
Three Dimensional ◽  
Soil Heterogeneity ◽  
Experimental Mesocosms

Transient Response of Gradient-Based Optimization for Ground Source Heat Exchangers

2019 ◽  
Author(s):  
Anthony A. DiCarlo ◽  
Rickey A. Caldwell
Keyword(s):  
Finite Element ◽  
Gradient Descent ◽  
Three Dimensional ◽  
Ambient Air ◽  
Element Model ◽  
Soil Heterogeneity ◽  
Initial Guess ◽  
Heating And Cooling ◽  
Ground Source ◽  
Critical Locations

Abstract The efficiency of ground source heating and cooling can be improved during installation by utilizing non-uniform properties of the soil. This paper presents a transient analysis of a computed optimal distribution of heterogeneous soils with varying thermal conductivities. This optimal configuration was computed via a gradient descent approach. The numerically simulated case studies demonstrate an improved performance when utilizing this approach to maximize the overall efficiency. The focus of this study is optimization of the soil heterogeneity surrounding the ground heat exchanger composed of pipes buried 2 meters underground. Finite element mathematics is used for the optimization algorithm. The finite element cells are treated as isotropic material voxels. The variation of material thermal conductivity in individual cells is employed as the optimizing variable. The updated conductivities are verified to ensure they are within the design domain. This method computes the sensitivities for the search direction (i.e. the gradient descent direction) utilizing the equations employed in the finite element mathematics. The optimization solution commences with the finite element model and applied boundary conditions. An initial guess is made of the elements’ conductivity. Based on these conductivities, the initial temperature is computed and later implemented to estimate the gradient. The global geometric conductivity matrix is assembled once in this process from the element geometric conductivity matrices. The objective function presented in this work maximizes the temperature at the critical locations. For this study, the critical locations are the location of the pipes. A three-dimensional, transient thermal simulation is developed based upon the optimized configuration for the soil. The monthly mean diurnal ambient air temperature variations for the months in the Northeast United States representing winter and summer are implemented in this study along with typical solar loading for each season. The results are presented for both a baseline homogeneous soil configuration and the optimized configuration. The results illustrate the benefits of an optimized soil configuration to maximize performance.

scholarly journals Effects of soil heterogeneity on susceptibility of shallow landslides

Landslides ◽  
2021 ◽  
Author(s):  
Emir Ahmet Oguz ◽  
Ivan Depina ◽  
Vikas Thakur
Keyword(s):  
Monte Carlo ◽  
Spatial Variability ◽  
Landslide Susceptibility ◽  
Three Dimensional ◽  
Soil Heterogeneity ◽  
Shallow Landslides ◽  
Model Parameters ◽  
The Monte Carlo Method ◽  
Proposed Model ◽  
Susceptibility Model

AbstractUncertainties in parameters of landslide susceptibility models often hinder them from providing accurate spatial and temporal predictions of landslide occurrences. Substantial contribution to the uncertainties in landslide assessment originates from spatially variable geotechnical and hydrological parameters. These input parameters may often vary significantly through space, even within the same geological deposit, and there is a need to quantify the effects of the uncertainties in these parameters. This study addresses this issue with a new three-dimensional probabilistic landslide susceptibility model. The spatial variability of the model parameters is modeled with the random field approach and coupled with the Monte Carlo method to propagate uncertainties from the model parameters to landslide predictions (i.e., factor of safety). The resulting uncertainties in landslide predictions allow the effects of spatial variability in the input parameters to be quantified. The performance of the proposed model in capturing the effect of spatial variability and predicting landslide occurrence has been compared with a conventional physical-based landslide susceptibility model that does not account for three-dimensional effects on slope stability. The results indicate that the proposed model has better performance in landslide prediction with higher accuracy and precision than the conventional model. The novelty of this study is illustrating the effects of the soil heterogeneity on the susceptibility of shallow landslides, which was made possible by the development of a three-dimensional slope stability model that was coupled with random field model and the Monte Carlo method.

The orbit of Pluto over a long interval of time

1966 ◽  
Vol 25 ◽  
pp. 227-229 ◽  
Author(s):  
D. Brouwer
Keyword(s):  
Periodic Orbit ◽  
Numerical Integration ◽  
Restricted Problem ◽  
Three Dimensional ◽  
The Third ◽  
Circular Restricted Problem ◽  
Resonance Relation

The paper presents a summary of the results obtained by C. J. Cohen and E. C. Hubbard, who established by numerical integration that a resonance relation exists between the orbits of Neptune and Pluto. The problem may be explored further by approximating the motion of Pluto by that of a particle with negligible mass in the three-dimensional (circular) restricted problem. The mass of Pluto and the eccentricity of Neptune's orbit are ignored in this approximation. Significant features of the problem appear to be the presence of two critical arguments and the possibility that the orbit may be related to a periodic orbit of the third kind.

Conformation of Ribosomes from Escherichia Coli

1974 ◽  
Vol 32 ◽  
pp. 210-211
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Binding Sites ◽  
Ribosomal Proteins ◽  
Fluorescent Dyes ◽  
Protein Biosynthesis ◽  
Three Dimensional ◽  
Spatial Arrangement ◽  
Dimensional Structure ◽  
Complete Understanding ◽  
And Function

The present knowledge of the three-dimensional structure of ribosomes is far too limited to enable a complete understanding of the various roles which ribosomes play in protein biosynthesis. The spatial arrangement of proteins and ribonuclec acids in ribosomes can be analysed in many ways. Determination of binding sites for individual proteins on ribonuclec acid and locations of the mutual positions of proteins on the ribosome using labeling with fluorescent dyes, cross-linking reagents, neutron-diffraction or antibodies against ribosomal proteins seem to be most successful approaches. Structure and function of ribosomes can be correlated be depleting the complete ribosomes of some proteins to the functionally inactive core and by subsequent partial reconstitution in order to regain active ribosomal particles.

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