Branch Inclination Research Articles

Calculated Deposition in Growing Tracheobronchial Airways: Effect of Growth-Rate Assumptions

Most current deterministic computer dosimetry models use idealized dichotomous symmetrical infant, child, and adolescent tracheobronchial geometries for dosimetry predictions. These tracheobronchial geometries were derived from either the morphometric measurements of J. D. Mortensen and colleagues or those of R. F. Phalen and colleagues. The airway growth curves used to create these geometries are typically means from all airways within a single generation in the tracheobronchial tree. This idealized approach implies that the growth rate of all airways in the same generation is identical (symmetric growth, SG), which is unlikely. In this study, existing morphometric measurements of airway dimensions were used to determine growth equations for airway length, diameter, branch angle, and inclination to gravity as a function of body height for each airway in the first four tracheobronchial generations. Tracheobronchial geometries (asymmetrical growth, AG) were created from these growth curves for the first 4 tracheobronchial generations representing a 4- and 11-yr-old child and an adult. Particle deposition predictions for steady inspiratory flow using 0.1- to 20-μm diameter monodisperse particles in these AG geometries were compared with predictions using the SG geometries using the uniform growth rate approach. Each airway in the first four generations had a unique airway length and diameter growth rate. Airway branch angle and inclination to gravity did not change as a function of body height. The unique airway growth rates resulted in significant differences in predicted deposition efficiency between the AG and SG geometry. Use of AG geometry may provide improved estimates of regional particle deposition in infants, children, and adolescents.

Winter chemical leaching from deciduous tree branches as a function of branch inclination angle in central Massachusetts

AbstractLeaching is an important process in the biogeochemical cycling of nutrients from above‐ground vegetative surfaces to the forest floor. Little is known about winter leaching from deciduous tree species and the influence of branch inclination angle on leachate chemistry. Using a set of field‐based isolated branches harvested from mature crowns of Betula lenta, Carya glabra and Quercus rubra, we tested the null hypothesis that during winter neither branch inclination angle nor branch species would have a detectable influence on differences in leachate chemistry and the quantity of intercepted precipitation from the branch surface. Leachate concentrations were significantly greater from branches inclined at 20° than 5° or 38°. Absolute nutrient inputs were also greatest for branches inclined at 20°. The significantly enriched branchflow and greater total nutrient input from branches inclined at 20° were attributed to increased residence time of intercepted precipitation with the branch surface, the lower probability of branch drip than branches inclined at 5°, and only minimal differences in branchflow quantity compared with branches inclined at 38°. Branchflow was more enriched from all three branch angles during precipitation events of longer duration and lower intensity than shorter, intense events. The leachate quantities of K+ and Ca2+ differ significantly among species. Carya glabra and Quercus rubra leached more K+ than Betula lenta. All three species leached significantly different amounts of Ca2+, with Quercus rubra leaching the most and Carya glabra the least. The adaptive geometry of deciduous canopy trees should be considered in relation to the interception of precipitation and aqueous leaching during winter when the canopy is leafless. Copyright © 2002 John Wiley & Sons, Ltd.

Effect of small branch inclination on gas–liquid flow separation in T junctions

AbstractA model developed calculates the mass intake fraction of gas and liquid phase during gas–liquid flow with small liquid holdup values (ϵL ≤ 0.1) through regular T junctions with small branch inclinations. It was derived from the steady‐state macroscopic mechanical energy balance (extended Bernoulli equation) applied to the “inlet‐to‐run” streamline and “inlet‐to‐branch” streamline of both gas and liquid phases. The model results are compared with experimental data of the system air/water–glycerol (0, 33, and 60 wt. %) flowing through a regular (D1 = D2 = D3 = 0.051 m) T junction with branch inclinations ranging from 0° to 0.5°. It was found that the gas–liquid flow split behavior is affected strongly by the liquid viscosity and by branch inclinations of 0.1° and higher. The results predicted with the model agree well with experimental results obtained in a regular T junction with a horizontal inlet run and an inclined side arm.

Investigation of strain induced patterning in superlattices by grazingincidence diffraction - comparison of morphological and strainordering

Symmetrically strained superlattices on off-oriented substrates are studied by x-ray grazing incidence diffraction in order to investigate compositional ordering separately from the related lattice strain correlation depending on the lattice mismatch. Narrow grating rods in strain-insensitive reciprocal space maps indicate a remarkably periodic lateral morphological ordering. Significant differences are observed in strain sensitive maps, where grating rod broadening indicates strain fluctuations. From the inclination of satellite branches in the maps, the direction of interface replication and of strain replication can be determined separately for the strained layer superlattice and for the low strained capping layers.

Substrate use of three epiphytic bromeliads

In the moist tropical forest of Barro Colorado Island, Panama, the distribution of three epiphytic bromehads growing on the host tree species Annona glabra was studied with respect to size of the epiphyte, substrate height, diameter, branch inclination and position relative to the periphery of the crown There were significant interspecific differences for almost all environmental variables, but there were no size‐related changes in distribution patterns The results suggest that a safe germination site is also a potential growing site for mature plants, and that mortality does not correlate with any of the measured parameters

Modelling crown shape of Piceaabies: spacing effects

A model of branch length increment and inclination was developed for Piceaabies (L.) Karst. to describe the dynamics of crown shape. Four trees belonging to the provenance Istebna, from Poland, were sampled in an experimental plot where density varied continuously from 200 to 10 000 stems/ha. Sampling along the density gradient enabled us to study the effect of spacing on tree morphology and development. The model of branch extension is based on height growth and on the year of elongation of the branch. A second model describes the change in branch inclination. Branch spread increased with between-tree spacing, whereas branch inclination was affected by crown contact; competition was then divided into two components: (i) direct mechanical contact and (ii) global resource depletion. The sample trees were young (26 years), so height growth was mainly linear and the effect of apical control could not be tested. This study provides a simple model of crown shape development that can be used in a more detailed process-based model. Simulations are presented based only on height growth. For wood quality purposes, the relationship between branch diameter and branch length is provided to give access to the knottiness of the stem. The limitations of the sample are discussed in view of a more general use of these models.

Spatial Distribution of Vascular Epiphytes on Three Emergent Canopy Trees in French Guiana

The distribution of vascular epiphytes was analyzed on three emergent trees (Hura crepitans, Ceiba pentandra, and Couratari stellata). A total number of 77 species, including 46 orchids, in 17 families was recorded. Number of species was highest in the center of the tree crowns while cover was highest in the middle third of the crown or equally distributed. This leads to the assumption that succession does not always reach equilibrium on old branches towards crown center. Distribution patterns of single species do not necessarily correspond to that of the total epiphyte mass. The entire epiphyte cover is highest on the top of branches while certain species, that could be discussed as specialists on the basis of particular life-form characteristics, are equally abundant on the bottom. There was no clear distribution pattern with respect to branch inclination. Distribution patterns are partly explained by the life-form of the plants.

Finite-Element Modeling of Tubular Joints. I: Numerical Results

The results of a study of 12 tubular joint models with varying branch to chord diameter ratios β and branch inclination angles θ, subjected to axial tension, axial compression, and in-plane bending moment, are presented. The analyses were performed using finite-element software that is capable of modeling elasto-plastic material behavior and geometric nonlinearities as well as ductile and brittle fracture. The results showed that the current use of sin(θ) in design equations for inclined branches is reasonable, but somewhat conservative. When compared with the current experimental database, a close correlation of results was obtained for all axial tension cases, and for axial compression and in-plane bending moment cases for low to moderate β values. For a β value of 1 and compression and bending loads, the enhanced strength that was observed was attributed to uncertainty in the definition of failure, and the effects of various support conditions and chord lengths in the experimental studies. It is recommended that these properties be standardized for the definition of the database.

SELF-OSCILLATIONS OF AN OPTICALLY BISTABLE ELEMENT WITH VERY BROAD HYSTERESIS IN A HYBRID RING CAVITY

We investigate thermally induced optical nonlinearity of a glass doped with semiconductor quantum dots. With the feedback of a Fabry-Perot resonator this glass shows dispersive optical bistability. The reflected light signal is coupled to a hybrid ring cavity with a round trip time much longer than that of the Fabry-Perot resonator and even longer than the thermal relaxation time of the glass. The self-oscillations occurring for certain input parameters are regular and the appearance of different modes as a function of the light intensity coupled to the resonator is observed. Due to the broad hysteresis and the high inclination of both branches of the bistable loop we observe large numbers of ascending and descending steps in the output intensity, i.e., long oscillation periods. A simple model of adiabatic simulations by an iterated map shows that the mode structure follows a Farey-tree construction.

Canopy development in young sugi (Cryptomeria japonica) stands in relation to changes with age in crown morphology and structure

In young sugi (Cryptomeria japonica D. Don) stands, crown shape (crown length/crown diameter) ratio, average branch inclination, and spatial density of foliage in the crown increased with stand age. Within crowns, foliage distribution increased from the apex downward and, until crown closure, reached a maximum near the crown base. After crown closure, the maximum occurred near the middle of the crown. In each stand, foliage distribution in the canopy showed almost the same vertical change over time as it did in individual crowns. The vertical distribution of foliage in the canopy moved upward with stand age, accompanied by an increase in canopy depth and leaf mass. The shape of the vertical distribution was almost symmetrical between the upper and lower halves in the closed stands, although slightly skewed downward. The logarithm of average spatial density decreased linearly as cumulative leaf mass increased with distance from the top of the canopy. The total cross-sectional area of the crowns exceeded the stand area from the middle of the canopy downward in the closed stands because of crown overlap. However, partly because of changes in crown morphology and structure, the increase in leaf mass with stand age did not always cause more severe crown competition.

Analysis of the morphology and structure of crowns in a young sugi (Cryptomeria japonica) stand

Crown form, vertical changes in branch inclination and vertical distribution of foliage density in a young sugi (Crytomeria japonica D. Don) stand were analyzed using allometric equations. Tall trees had deeper crowns than short trees, whereas the crown diameters of both tall and short trees were similar. Apical roundness was more pronounced in the lower-story trees, which were characterized by umbrella-shaped crowns. The vertical distribution of foliage density was approximated by a nearly symmetrical curve. Tall trees had higher spatial densities of foliage than short trees. Branch inclination also varied significantly with tree height. The middle-story trees had the largest branch inclinations and the lower-story trees had the smallest branch inclinations. Even in young uniform stands, crown morphology and structure were modified in response to the light environment.

Raindrop impact and water flow on the vegetative surfaces of trees and the effects on stemflow and throughfall generation

AbstractThe physical processes of raindrop impact and water flow on the leaves and branches of selected tropical tree species were examined under laboratory conditions using simulated rainfall. Inclined branches were found to be particularly efficient in detaining impacting water droplets. This efficiency in raindrop detention increases linearly as a function of branch inclination on branches that are initially dry. On branches that have been thoroughly wetted, this increase in raindrop detention with branch inclination is best expressed as a logarithmic function. At branch inclinations of 60° above the horizontal, the quantity of branchflow was found to be > 80 per cent of the total quantity of impacting rainfall, indicating that < 20 per cent was lost to rainsplash. The strong positive relationship between branchflow and branch inclination explains why trees with large projected areas of steeply inclined upthrust branches have significant quantities of intercepted water draining from their branches and trunks under heavy rainfall conditions. This drainage from the woody frame of trees influences surficial processes by generating both stemflow and large throughfall droplets.

Limb Impact Harvesting, Part III: Model Studies

ABSTRACT SIMULATION studies using the finite element model presented in Part I showed that impacting from below in a direction normal to the limb (transverse) was superior to impacting the limb in any other direction. The optimal direction of the inclination of branches of a Y-shaped open center tree was found to be between 45 deg and 60 deg from the horizontal for a transverse im-pact from below. The occurrence of stem-pull (i.e., fruit detachment without the stem intact) was dependent on the angle of attachment of the stem to the spur, the angle of attachment of the spur to the limb, the direction of im-pact force, the modulus of elasticity and the diameter of the stem.

Extension of the Optical Diffraction Analysis Technique for Estimating Forest Canopy Geometry.

Optical diffraction analysis of in situ ground photographs has previously been used to estimate foliage angle distributions in grassland canopies. These canopies are typically characterized by a single component-leaves-and the foliage is highly linear in nature. In this paper, the diffraction technique is extended to a multicomponent forest canopy containing needles and branches. Additional convolution and coordinate transformations are used to estimate the branch and needle angle frequency distributions for top, middle, and base sections of two lodgepole pine (Pinus contorta) trees. The resulting distributions show that the branch inclination angles tend to increase as one proceeds to the tree tops. The needle inclination angle distribution was relatively constant for all layers, and it is believed that this distribution is characteristic of a large class of needle-bearing species.