A Comparison of Two Photographic Techniques for Estimating Foliage Angle Distribution

1977 ◽  
Vol 25 (5) ◽  
pp. 545 ◽  
Author(s):  
JA Smith ◽  
RE Oliver ◽  
JK Berry
Keyword(s):  
Integral Equation ◽  
Solar Radiation ◽  
Ground Level ◽  
Theoretical Models ◽  
Angle Distribution ◽  
Plant Canopy ◽  
Agropyron Smithii ◽  
In Situ Method ◽  
Vegetation Canopies

There is an increasing interest in theoretical models which describe the interaction of solar radiation with vegetation canopies. Common to these models is a need to describe mathematically the geometric structure of the plant canopy. The amount of radiation reflected or absorbed by the canopy is primarily determined by the distribution of gaps in the foliage with respect to the radiation source. A measure of canopy geometry related to gap frequency at various view angles is the distribution of leaf angles. Two methods for measuring the distribution of leaf angles are discussed. The first method is to project orthogonally and photograph individual plants and relate the measured leaf angles in the projections to the canopy distribution of angles. The second method is a rapid in situ method based on ground level multiple view angle photography. A Fredholm integral equation relating foliage angles to the proportion of gap in the canopy as a function of view angle is then solved. Comparisons of the results using the two methods are made for a canopy of Western wheat grass (Agropyron smithii).

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).

Solar radiation attenuation in a hillside jack pine forest

1982 ◽  
Vol 60 (10) ◽  
pp. 1913-1922
Author(s):  
D. W. A. Whitfield ◽  
L. A. Mehlenbacher ◽  
C. Labine
Keyword(s):  
Solar Radiation ◽  
Field Measurements ◽  
Jack Pine ◽  
Individual Plant ◽  
Plant Canopy ◽  
Model Output ◽  
Area Index ◽  
Scattering Effects ◽  
Pine Trees ◽  
Vegetation Canopies

A modelling technique for penetration of solar radiation into clumped vegetation canopies is described. It combines Monte-Carlo simulation to determine ray pathlengths through individual plant canopy envelopes with exponential attenuation along these rays. The technique is applied to a hillside forest of randomly located and sized jack pine trees. Scattering effects are incorporated and the model output is compared with field measurements. The results depend on the shape of the tree outline. Attenuation is less rapid with downward cumulative leaf area index than in a randomly dispersed canopy.

scholarly journals Application of Furcellaran Nanocomposite Film as Packaging of Cheese

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1428
Author(s):  
Agnieszka Pluta-Kubica ◽  
Ewelina Jamróz ◽  
Gohar Khachatryan ◽  
Adam Florkiewicz ◽  
Pavel Kopel
Keyword(s):  
Silver Nanoparticles ◽  
Nanocomposite Film ◽  
Microbiological Quality ◽  
Inhibitory Effect ◽  
Quality Properties ◽  
In Situ Method ◽  
And Migration ◽  
Total Bacteria

There is a serious need to develop and test new biodegradable packaging which could at least partially replace petroleum-based materials. Therefore, the objective of this work was to examine the influence of the recently developed furcellaran nanocomposite film with silver nanoparticles (obtained by an in situ method) on the quality properties of two cheese varieties: a rennet-curd (gouda) and an acid-curd (quark) cheese. The water content, physicochemical properties, microbiological and organoleptic quality of cheese, and migration of silver nanoparticles were examined. Both the number of Lactococcus and total bacteria count did not differ during storage of gouda regardless of the packaging applied. The number of Lactococcus decreased in analogous quark samples. The use of the film slowed down and inhibited the growth of yeast in gouda and quark, respectively. An inhibitory effect of this film on mold count was also observed; however, only regarding gouda. The level of silver migration was found to be lower in quark than in gouda. The film improved the microbiological quality of cheeses during storage. Consequently, it is worth continuing research for the improvement of this film in order to enable its use in everyday life.

Photocatalytic degradation of tetracycline under visible light using TiO2@sulfur doped carbon nitride nanocomposite synthesized via in-situ method

2021 ◽  
Vol 9 (4) ◽  
pp. 105560
Author(s):  
Krishnan Divakaran ◽  
Amanulla Baishnisha ◽  
Vellaichamy Balakumar ◽  
Krishnan Nattamai Perumal ◽  
Chandran Meenakshi ◽  
...  
Keyword(s):  
Visible Light ◽  
Photocatalytic Degradation ◽  
Carbon Nitride ◽  
In Situ Method

Obtainable Method of Measuring the Solar Radiant Flux Based on Silicone Photodiode Element

2016 ◽  
Vol 824 ◽  
pp. 477-484 ◽  
Author(s):  
Miroslav Čekon ◽  
Richard Slávik ◽  
Peter Juras
Keyword(s):  
Solar Radiation ◽  
Solar Irradiance ◽  
Climate Science ◽  
Radiant Flux ◽  
Silicon Photodiode ◽  
Building Science ◽  
Solar Instruments ◽  
Solar Radiation Exposure ◽  
Building Physics

Solar radiation exposure and its monitoring does have not only the importance for climate science and meteorology however is equally of highly relevant use for the field of Building Science as primarily those of analyzing thermal aspects in building physics. Here the measuring of solar irradiance by means of well-established solar instruments can be applied whose advances have been undergoing steep progress. Currently, a silicon photodiode element, as a truly obtainable form, may have a feasible exploitation in the field of building applications concerning the solar radiant flux quantifying. It represents a small optoelectronic element and has a several exploitable advantages. The paper presents a perspective alternative to monitor solar irradiance. Own measurement assembly is proposed and introduced. Initial in-situ measurements are performed and final comparability with existing commercial solar instruments is presented. An obtained correlation with existing types demonstrates its applicability to the field of building science and solar energy.

Dynamic Modeling of Solar Radiation Disturbances Based on a Biomimetic Cloud Shading Model

2018 ◽  
Vol 140 (2) ◽  
Author(s):  
Jesús García ◽  
Iván Portnoy ◽  
Ricardo Vasquez Padilla ◽  
Marco E. Sanjuan
Keyword(s):  
Time Series ◽  
Solar Radiation ◽  
Control Strategies ◽  
Ground Level ◽  
Direct Solar Radiation ◽  
Complex Phenomenon ◽  
Two Dimensional ◽  
Multi Objective Optimization ◽  
Tuning Parameters ◽  
Radiation Time

Variation in direct solar radiation is one of the main disturbances that any solar system must handle to maintain efficiency at acceptable levels. As known, solar radiation profiles change due to earth's movements. Even though this change is not manipulable, its behavior is predictable. However, at ground level, direct solar radiation mainly varies due to the effect of clouds, which is a complex phenomenon not easily predictable. In this paper, dynamic solar radiation time series in a two-dimensional (2D) spatial domain are obtained using a biomimetic cloud-shading model. The model is tuned and compared against available measurement time series. The procedure uses an objective function based on statistical indexes that allow extracting the most important characteristics of an actual set of curves. Then, a multi-objective optimization algorithm finds the tuning parameters of the model that better fit data. The results showed that it is possible to obtain responses similar to real direct solar radiation transients using the biomimetic model, which is useful for other studies such as testing control strategies in solar thermal plants.

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