scholarly journals A New Model for Size-Dependent Tree Growth in Forests

PLoS ONE ◽  
2016 ◽  
Vol 11 (4) ◽  
pp. e0152219 ◽  
Author(s):  
Masae Iwamoto Ishihara ◽  
Yasuo Konno ◽  
Kiyoshi Umeki ◽  
Yasuyuki Ohno ◽  
Kihachiro Kikuzawa
Keyword(s):  
Tree Growth ◽  
New Model ◽  
Size Dependent

Size dependent associations between tree diameter growth rates and functional traits in an Asian tropical seasonal rainforest

2021 ◽  
Vol 48 (2) ◽  
pp. 231
Author(s):  
Yu-Mei Yan ◽  
Ze-Xin Fan ◽  
Pei-Li Fu ◽  
Hui Chen ◽  
Lu-Xiang Lin
Keyword(s):  
Functional Traits ◽  
Tree Growth ◽  
Growth Rates ◽  
Small Diameter ◽  
Diameter Growth ◽  
Ontogenetic Shifts ◽  
Size Classes ◽  
Size Dependent ◽  
Large Trees ◽  
Leaf Economic Spectrum

Many studies focus on the relationships between plant functional traits and tree growth performances. However, little is known about the ontogenetic shifts of the relationships between functional traits and tree growth. This study examined associations between stem and leaf functional traits and growth rates and their ontogenetic shifts across 20 tropical tree species in a tropical seasonal rainforest in Xishuangbanna, south-west China. For each species, physiological active branches of individual trees belonged to three size classes (i.e. small, diameter at breast height (DBH) 5–10 cm; middle, DBH 10–20 cm; big, DBH >20 cm) were sampled respectively. We measured 18 morphological and structural traits, which characterised plant hydraulic properties or leaf economic spectrum. Associations between diameter growth rates and functional traits were analysed across three size classes. Our results revealed that diameter growth rates of big-sized trees were mainly related to traits related to plant hydraulic efficiency (i.e. theoretical hydraulic conductivity (Ktheo) and leaf vein density (Dvein)), which suggests that the growth of large trees is limited mainly by their xylem water transport capacity. For middle-sized trees, growth rates were significantly related to traits representing leaf economic spectrum (i.e. specific leaf area (SLA), individual leaf mass (ILM), palisade thickness (PT) and spongy thickness (SP)). Diameter growth rates of small-sized trees were not correlated with hydraulic or leaf economic traits. Thus, the associations between tree growth rates and functional traits are size dependent. Our results suggest ontogenetic shift of functional traits which could potential contribute to different growth response to climate change.

PULL-IN INSTABILITY OF CIRCULAR PLATE MEMS: A NEW MODEL BASED ON STRAIN GRADIENT ELASTICITY THEORY

2012 ◽  
Vol 04 (01) ◽  
pp. 1250003 ◽  
Author(s):  
BINGLEI WANG ◽  
SHENJIE ZHOU ◽  
JUNFENG ZHAO ◽  
XI CHEN
Keyword(s):  
Elasticity Theory ◽  
Strain Gradient ◽  
Plate Thickness ◽  
Gradient Elasticity ◽  
Strain Gradient Elasticity ◽  
New Model ◽  
Size Dependent ◽  
Strain Gradient Elasticity Theory ◽  
Gradient Elasticity Theory ◽  
Material Length Scale

Size-dependent characteristics have been widely observed in microscale devices. For the electrostatically actuated circular microplate-based MEMS, we propose a new model to predict the size-dependent pull-in instability based on the strain gradient elasticity theory. The model embeds three material length scale parameters (MLSPs), which can effectively predict the size-dependent pull-in voltage. The model can be reduced to the classical continuum model when MLSPs are ignored. The results show that the normalized pull-in voltage predicted by the present model increases nonlinearly with the decrease of the size scale of the plate, and the size effect becomes prominent if the characteristic dimension (plate thickness) is on the order of microns or smaller. The effects of the plate thickness and gap on the pull-in voltage are also investigated.

scholarly journals Size‐dependent nutrient limitation of tree growth from subtropical to cold temperate forests

2017 ◽  
Vol 32 (1) ◽  
pp. 95-105 ◽  
Author(s):  
Yong Li ◽  
Dashuan Tian ◽  
Hao Yang ◽  
Shuli Niu
Keyword(s):  
Nutrient Limitation ◽  
Tree Growth ◽  
Temperate Forests ◽  
Size Dependent

Mechanical Behavior Analysis of Micro-Scaled Functionally Graded Timoshenko Beams by the Strain Gradient Theory

2012 ◽  
Author(s):  
S. A. Tajalli ◽  
M. H. Kahrobaiyan ◽  
M. Rahaeifard ◽  
M. T. Ahmadian ◽  
M. R. Movahhedy ◽  
...  
Keyword(s):  
Strain Gradient ◽  
Functionally Graded ◽  
Strain Gradient Theory ◽  
Gradient Theory ◽  
Length Scale ◽  
Timoshenko Beams ◽  
New Model ◽  
Scale Parameters ◽  
Size Dependent ◽  
Special Cases

In this paper, a size-dependent formulation is developed for Timoshenko beams made of functionally graded materials (FGM). The developed formulation is based on the strain gradient theory; a non-classical continuum theory able to capture the size-effect in micro-scaled structures. Considering the material length scale parameters of the FG beams vary through the thickness, the new equivalent length scale parameters are proposed as functions of the constituents’ length scale parameters to describe the size-dependent static and dynamic behavior of FG microbeams. The governing differential equations of equilibrium and both classical and non-classical sets of boundary conditions are derived for the proposed strain gradient FG Timoshenko beam using variational approach. As case studies, the static bending deformation of the new model is investigated for an FG simply supported beam made of tungsten/copper (W/Cu) in which properties are varying through the thickness according to a power law. The results of the new model are compared to those of the modified couple stress and the classical theories where the two latter theories are special cases of the strain gradient theory.

Production and STEM examination of controlled-size silver clusters

1983 ◽  
Vol 41 ◽  
pp. 338-339
Author(s):  
M. A. Listvan ◽  
R. P. Andres
Keyword(s):  
Cluster Size ◽  
Metal Clusters ◽  
Experimental Parameter ◽  
Carbon Films ◽  
Metal Species ◽  
Silver Clusters ◽  
Free Jet ◽  
Size Dependent ◽  
Cluster Properties ◽  
Controllable Size

Knowledge of the function and structure of small metal clusters is one goal of research in catalysis. One important experimental parameter is cluster size. Ideally, one would like to produce metal clusters of regulated size in order to characterize size-dependent cluster properties.A source has been developed which is capable of producing microscopic metal clusters of controllable size (in the range 5-500 atoms) This source, the Multiple Expansion Cluster Source, with a Free Jet Deceleration Filter (MECS/FJDF) operates as follows. The bulk metal is heated in an oven to give controlled concentrations of monomer and dimer which were expanded sonically. These metal species were quenched and condensed in He and filtered to produce areosol particles of a controlled size as verified by mass spectrometer measurements. The clusters were caught on pre-mounted, clean carbon films. The grids were then transferred in air for microscopic examination. MECS/FJDF was used to produce two different sizes of silver clusters for this study: nominally Ag6 and Ag50.

The Hitachi Model HS-8 Electron Microscope

1967 ◽  
Vol 25 ◽  
pp. 238-239
Author(s):  
H. Akabori ◽  
K. Nishiwaki ◽  
K. Yoneta
Keyword(s):  
Electron Microscope ◽  
New Model ◽  
Predecessor Model

By improving the predecessor Model HS- 7 electron microscope for the purpose of easier operation, we have recently completed new Model HS-8 electron microscope featuring higher performance and ease of operation.

Transfer Technique for Electron Microscopy of Membrance Filter Samples

1974 ◽  
Vol 32 ◽  
pp. 554-555
Author(s):  
Lawrence W. Ortiz ◽  
Bonnie L. Isom
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Pore Size ◽  
Membrane Filters ◽  
Size Dependent

A procedure is described for the quantitative transfer of fibers and particulates collected on membrane filters to electron microscope (EM) grids. Various Millipore MF filters (Millipore AA, HA, GS, and VM; 0.8, 0.45, 0.22 and 0.05 μm mean pore size) have been used with success. Observed particle losses have not been size dependent and have not exceeded 10%. With fibers (glass or asbestos) as the collected media this observed loss is approximately 3%.

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