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

1979 ◽  
Vol 27 (5) ◽  
pp. 575 ◽  
Author(s):  
DS Kimes ◽  
JA Smith ◽  
JK Berry
Keyword(s):  
Diffraction Analysis ◽  
Pinus Contorta ◽  
Forest Canopy ◽  
Optical Diffraction ◽  
Angle Distribution ◽  
Coordinate Transformations ◽  
Frequency Distributions ◽  
Analysis Technique ◽  
Inclination Angles

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.

Note on Paper 'Optical Diffraction Analysis for Estimating Foliage Angle Distribution in Grassland Canopies', by J. A. Smith and J. K. Berry.

1980 ◽  
Vol 28 (4) ◽  
pp. 495
Author(s):  
ARG Lang
Keyword(s):  
Angular Distribution ◽  
Diffraction Analysis ◽  
Probability Density ◽  
Inclination Angle ◽  
Leaf Length ◽  
Optical Diffraction ◽  
Angle Distribution

It is shown that a technique previously described for analysing foliage angular distribution in grassland canopies is not well based theoretically because it does not give exact measures of the probability density of longitudinal leaf length with respect to inclination angle.

ORIENTATION OF SORBUS AUCUPARIA LEAVES BY THE RESULTS OF FIELD SURVEYS IN THE TERRITORY OF THE LENINGRAD REGION

2021 ◽  
Author(s):  
I. V. Matelenok ◽  
◽  
F. A. Alekseev ◽  
E. A. Evdokimova ◽  
◽  
...  
Keyword(s):  
Forest Canopy ◽  
Integral Function ◽  
Leaf Angle ◽  
Distribution Data ◽  
Leningrad Region ◽  
Angle Distribution ◽  
Office Work ◽  
Sorbus Aucuparia ◽  
Inclination Angles ◽  
Leaf Angle Distribution

Methods for retrieving leaf inclination angles in a forest canopy are considered. To acquire data on the orientation of Sorbus aucuparia leaves, a technique based on leveled camera digital photography well suited for conducting surveys in a boreal forest was used. In the course of field and office work, leaf angle distribution data for the specified species in the Priozersky district of the Leningrad region was obtained and analyzed. Values of the Ross-Nielson integral function were estimated.

Optical Diffraction Analysis for Estimating Foliage Angle Distribution in Grassland Canopies

1979 ◽  
Vol 27 (2) ◽  
pp. 123 ◽  
Author(s):  
JA Smith ◽  
JK Berry
Keyword(s):  
Probability Distributions ◽  
Optical Diffraction ◽  
Angle Distribution ◽  
Agropyron Smithii ◽  
Diffraction Patterns ◽  
Three Space ◽  
Non Destructive ◽  
Sampling Probability ◽  
Angular Bias

A non-destructive, rapid technique utilizing horizontal in situ ground photographs for estimating foliage angle distributions is discussed. Optical diffraction patterns generated from orthogonal photographs are analysed for angular bias by wedge sampling. Probability distributions for planar projections of foliage orientations are derived from these measurements and mathematically convo- luted to determine the actual three-space probability distribution function for foliage angles. The method is particularly appropriate for dense canopies which are difficult to measure by other tech- niques. The diffraction technique is evaluated for abstract canopies and for a canopy of Western wheat grass (Agropyron smithii). It also yields physically consistent interpretations for the phenolo- gical development of domestic Satanta wheat (Triticum aestivum).

Light Optical Diffraction Studies of Macromolecular Ultrastructure

1970 ◽  
Vol 28 ◽  
pp. 258-259
Author(s):  
Glen B. Haydon
Keyword(s):  
High Resolution ◽  
Diffraction Analysis ◽  
Diffraction Pattern ◽  
Electron Micrographs ◽  
Optical Diffraction ◽  
Electron Micrograph ◽  
Its Analysis ◽  
Resolution Electron ◽  
Diffraction Patterns

Analysis of light optical diffraction patterns produced by electron micrographs can easily lead to much nonsense. Such diffraction patterns are referred to as optical transforms and are compared with transforms produced by a variety of mathematical manipulations. In the use of light optical diffraction patterns to study periodicities in macromolecular ultrastructures, a number of potential pitfalls have been rediscovered. The limitations apply to the formation of the electron micrograph as well as its analysis.(1) The high resolution electron micrograph is itself a complex diffraction pattern resulting from the specimen, its stain, and its supporting substrate. Cowley and Moodie (Proc. Phys. Soc. B, LXX 497, 1957) demonstrated changing image patterns with changes in focus. Similar defocus images have been subjected to further light optical diffraction analysis.

Spectro-mechanical Characterization of Aromaticity and Maturity of Kerogens in Oil Shale at 6 nm Spatial Resolution

2018 ◽  
Author(s):  
Devon Jakob ◽  
Le Wang ◽  
Haomin Wang ◽  
Xiaoji Xu
Keyword(s):  
Spatial Resolution ◽  
Oil Shale ◽  
Infrared Imaging ◽  
Mechanical Characterization ◽  
Optical Diffraction ◽  
Chemical Compositions ◽  
Valuable Insight ◽  
Eagle Ford Shale

<p>In situ measurements of the chemical compositions and mechanical properties of kerogen help understand the formation, transformation, and utilization of organic matter in the oil shale at the nanoscale. However, the optical diffraction limit prevents attainment of nanoscale resolution using conventional spectroscopy and microscopy. Here, we utilize peak force infrared (PFIR) microscopy for multimodal characterization of kerogen in oil shale. The PFIR provides correlative infrared imaging, mechanical mapping, and broadband infrared spectroscopy capability with 6 nm spatial resolution. We observed nanoscale heterogeneity in the chemical composition, aromaticity, and maturity of the kerogens from oil shales from Eagle Ford shale play in Texas. The kerogen aromaticity positively correlates with the local mechanical moduli of the surrounding inorganic matrix, manifesting the Le Chatelier’s principle. In situ spectro-mechanical characterization of oil shale will yield valuable insight for geochemical and geomechanical modeling on the origin and transformation of kerogen in the oil shale.</p>

In Situ Analysis of Surface Contaminant Desorption during Low-Temperature Silicon Substrate Cleaning using Reflection Electron Energy Loss Spectrometry

1992 ◽  
Vol 259 ◽  
Author(s):  
Selmer S. Wong ◽  
Shouleh Nikzad ◽  
Channing C. Ahn ◽  
Aimee L. Smith ◽  
Harry A. Atwater
Keyword(s):  
Low Temperature ◽  
Energy Loss ◽  
Electron Energy ◽  
Core Loss ◽  
Temperature Dependent ◽  
Electron Energy Loss Spectrometry ◽  
Analysis Technique ◽  
Chemical Analysis Technique ◽  
Electron Energy Loss

ABSTRACTWe have employed reflection electron energy loss spectrometry (REELS), a surface chemical analysis technique, in order to analyze contaminant coverages at the submonolayer level during low-temperature in situ cleaning of hydrogen-terminated Si(100). The chemical composition of the surface was analyzed by measurements of the C K, O K and Si L2,3 core loss intensities at various stages of the cleaning. These results were quantified using SiC(100) and SiO2 as reference standards for C and O coverage. Room temperature REELS core loss intensity analysis after sample insertion reveals carbon at fractional monolayer coverage. We have established the REELS detection limit for carbon coverage to be 5±2% of a monolayer. A study of temperature-dependent hydrocarbon desorption from hydrogen-terminated Si(100) reveals the absence of carbon on the surface at temperatures greater than 200°C. This indicates the feasibility of epitaxial growth following an in situ low-temperature cleaning and also indicates the power of REELS as an in situ technique for assessment of surface cleanliness.

scholarly journals Insertion of Phosphenium Ions into a Bicyclo[1.1.0]Tetraphosphabutane Iron Complex

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3920
Author(s):  
Martin Weber ◽  
Gábor Balázs ◽  
Alexander V. Virovets ◽  
Eugenia Peresypkina ◽  
Manfred Scheer
Keyword(s):  
Diffraction Analysis ◽  
Room Temperature ◽  
31P Nmr ◽  
Spectroscopic Studies ◽  
Iron Complex ◽  
The Novel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Phosphenium Ions

By reacting [{Cp‴Fe(CO)2}2(µ,η1:1-P4)] (1) with in situ generated phosphenium ions [Ph2P][A] ([A]− = [OTf]− = [O3SCF3]−, [PF6]−), a mixture of two main products of the composition [{Cp‴Fe(CO)2}2(µ,η1:1-P5(C6H5)2)][PF6] (2a and 3a) could be identified by extensive 31P NMR spectroscopic studies at 193 K. Compound 3a was also characterized by X-ray diffraction analysis, showing the rarely observed bicyclo[2.1.0]pentaphosphapentane unit. At room temperature, the novel compound [{Cp‴Fe}(µ,η4:1-P5Ph2){Cp‴(CO)2Fe}][PF6] (4) is formed by decarbonylation. Reacting 1 with in situ generated diphenyl arsenium ions gives short-lived intermediates at 193 K which disproportionate at room temperature into tetraphenyldiarsine and [{Cp‴Fe(CO)2}4(µ4,η1:1:1:1-P8)][OTf]2 (5) containing a tetracyclo[3.3.0.02,7.03,6]octaphosphaoctane ligand.

scholarly journals Improved understanding of drought controls on seasonal variation in Mediterranean forest canopy CO<sub>2</sub> and water fluxes through combined in situ measurements and ecosystem modelling

2009 ◽  
Vol 6 (8) ◽  
pp. 1423-1444 ◽  
Author(s):  
T. Keenan ◽  
R. García ◽  
A. D. Friend ◽  
S. Zaehle ◽  
C. Gracia ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Forest Canopy ◽  
Moisture Stress ◽  
Mediterranean Ecosystems ◽  
Forest Growth ◽  
Water Fluxes ◽  
Soil Moisture Stress ◽  
Dynamic Global Vegetation Model ◽  
Forest Growth Model

Abstract. Water stress is a defining characteristic of Mediterranean ecosystems, and is likely to become more severe in the coming decades. Simulation models are key tools for making predictions, but our current understanding of how soil moisture controls ecosystem functioning is not sufficient to adequately constrain parameterisations. Canopy-scale flux data from four forest ecosystems with Mediterranean-type climates were used in order to analyse the physiological controls on carbon and water flues through the year. Significant non-stomatal limitations on photosynthesis were detected, along with lesser changes in the conductance-assimilation relationship. New model parameterisations were derived and implemented in two contrasting modelling approaches. The effectiveness of two models, one a dynamic global vegetation model ("ORCHIDEE"), and the other a forest growth model particularly developed for Mediterranean simulations ("GOTILWA+"), was assessed and modelled canopy responses to seasonal changes in soil moisture were analysed in comparison with in situ flux measurements. In contrast to commonly held assumptions, we find that changing the ratio of conductance to assimilation under natural, seasonally-developing, soil moisture stress is not sufficient to reproduce forest canopy CO2 and water fluxes. However, accurate predictions of both CO2 and water fluxes under all soil moisture levels encountered in the field are obtained if photosynthetic capacity is assumed to vary with soil moisture. This new parameterisation has important consequences for simulated responses of carbon and water fluxes to seasonal soil moisture stress, and should greatly improve our ability to anticipate future impacts of climate changes on the functioning of ecosystems in Mediterranean-type climates.

Optical Diffraction Analysis of Petrographic Thin Sections

Science ◽  
1974 ◽  
Vol 186 (4160) ◽  
pp. 234-239 ◽  
Author(s):  
P. C. Power ◽  
H. J. PincuS
Keyword(s):  
Diffraction Analysis ◽  
Optical Diffraction ◽  
Thin Sections
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