Fuelbed ignition potential and bark morphology explain the notoriety of the eucalypt messmate 'stringybark' for intense spotting

2011 ◽  
Vol 20 (7) ◽  
pp. 897 ◽  
Author(s):  
P. F. M. Ellis
Keyword(s):  
Moisture Content ◽  
Pinus Radiata ◽  
Laboratory Tests ◽  
Flight Behaviour ◽  
Outer Bark ◽  
Ignition Probability ◽  
Loss Of Life ◽  
Moisture Contents ◽  
Eastern Australia ◽  
Probability Weight

In south-eastern Australia, bark of the ‘stringybark’ eucalypt group, and notably that of messmate (Eucalyptus obliqua L’Hér.), is notorious for intense spotting and it is likely that firebrands of this type contribute significantly to loss of life and property during major wildfires. The fuelbed ignition potential by glowing samples was laboratory tested on excised sections of Pinus radiata D. Don litterbed at moisture contents between 2 and 8% and for ‘no-wind’ or for ‘wind’ of 1 m s–1. Prepared samples of outer bark between 0.5 and 1.6 g were combusted until they attained ~20% of initial mass before placement. For ‘no-wind’, flaming ignition did not occur and the probability of glowing ignition appeared to depend on the chance of contact with needles. For ‘wind’, the probability of flaming ignition was a function of sample glowing mass and fuelbed moisture content. Its ignition probability, weight-for-weight, appears to exceed that reported for other forest firebrands, including bark of E. globulus Labill. However, it is likely that the notoriety of messmate bark is also due, in part, to its morphology and in-flight behaviour. It is argued that firebrand laboratory tests to date may poorly reflect the ignition potential of similar samples after flight.

Figure 1. Anmonia-binding capacity of the three litters under laboratory conditions. 4. LIQUID-BINDING CAPACITY The absorption capacity of the litter determines the amount used, and also affects the functioning of hydraulic manure presses. Hie absorption capacity of litter depends on its initial moisture content. In the laboratory tests , peat had a much greater absorption capacity than other litters. Peat absorbed a maximum of 4.5 times its own weight of liquid, straw 3.5 times, cutter shavings 3.6 times and sawdust 1.5 times (4). The litters used in the tests had an initial moisture content of 20%, with the exception of peat, which contained 40% moisture. These moisture contents represent the working values for good-quality litters. Peat was far superior in terms of absoption capacity to the other litters. Litter should retain its absorption capacity even when under pressure, for example in a hydraulic manure press. The ability of litters to withstand pressure was tested by first allowing than to absorb either water or urine. The litters were then compressed in a hydraulic press for one hour as the pressure was increased stepwise from 20 N/an2 to 50 N/an2. The pressure exerted by hydraulic manure presses in practice is around 40-60 N/cm2. All the retained urine better than water. Sawdust was found to have the greatest resistance to pressure, retaining about 75% of the absorbed

1986 ◽  
pp. 197-197
Keyword(s):  
Moisture Content ◽  
Laboratory Tests ◽  
Binding Capacity ◽  
Initial Moisture Content ◽  
Hydraulic Press ◽  
Absorption Capacity ◽  
The Other ◽  
Moisture Contents ◽  
Laboratory Conditions ◽  
Better Than

Fire and the opening of Banksia ornata F. Muell. Follicles

1976 ◽  
Vol 24 (3) ◽  
pp. 329 ◽  
Author(s):  
AM Gill
Keyword(s):  
Moisture Content ◽  
Room Temperature ◽  
Dry Weight ◽  
Field Conditions ◽  
Abscission Layer ◽  
Moisture Contents ◽  
Follicle Rupture ◽  
Eastern Australia ◽  
Water Saturated ◽  
Increasing Temperature

Banksia ornata is a sclerophyll shrub, characteristic of the heaths of south-eastern Australia. Its follicles are almost entirely dependent on fire for rupture and release of seed, although a few open under ambient field conditions. At air-dry moisture content (10-12% oven-dry weight) temperatures in excess of about 75°C are required for the rupture of the abscission layer between the woody valves, the time of exposure necessary for rupture decreasing with increasing temperature. At higher moisture contents rupture is delayed. No rupture occurs when follicles are water-saturated and exposed to a temperature of 100° over long periods. Similarly, no rupture occurs at room temperature when follicles are dried under vacuum (to 1.4% oven-dry weight). After rupture, the extent of valve reflexion is greatest when follicle valves are driest. These results are interpreted as follows. Follicle rupture occurs when tension across the abscission zone exceeds its strength: moisture has a major role in affecting the tension, and temperature a major role in affecting the strength.

Variation of Live and Dead Fine Fuel Moisture in Pinus radiata Plantations of the Australian-Capital-Territory

1993 ◽  
Vol 3 (3) ◽  
pp. 155 ◽  
Author(s):  
EW Pook ◽  
AM Gill
Keyword(s):  
Moisture Content ◽  
Pinus Radiata ◽  
Dry Weight ◽  
Pine Plantations ◽  
Fuel Moisture ◽  
Atmospheric Conditions ◽  
Needle Age ◽  
Moisture Contents ◽  
Highly Correlated ◽  
Mean Differences

A study was made of the variation in moisture content of fine dead fuel (FFM) in relation to 1) differences of fuel type (needles, leaves, twigs, bark), 2) different fuel locations (dead canopy and surface litter), 3) contrasting management of plantations (unthinned-unpruned vs thinned-pruned) and 4) environmental factors (air temperature (T) and relative humidity (H); moisture content of duff (D) and topsoil (S)). The variation of live (green needle) fine fuel moisture content (LFMC) in relation to needle age, canopy location (shaded vs unshaded) and season was also studied in Pinus radiata D. Don plantations over 2 years. Mean differences of moisture content between the several types of fuel exposed to the same atmospheric conditions were generally significant and ranged from 0.6% (pine twigs vs eucalypt twigs) up to 2.8% oven dry weight (ODW) (eucalypt bark vs recently cast pine needles). T and H were highly correlated between study sites in pine plantations and an official meteorological station at Canberra airport, 15 km away. In the pine plantations, mid afternoon moisture contents of pine needle litter (litter FFMs) were mostly higher than moisture contents of dead needles in canopies (aerial FFMs); the mean differences between litter FFMs and aerial FFMs were statistically significant. FFMs in the unthinned-unpruned plantation were also generally higher than those in the thinned-pruned plantations. Regression analyses of relationships between FFM and environmental variables showed that T and H in combination explained a large proportion of the variation in aerial FFM but much less of the variation in litter FFM. However, the inclusion of either D or S in multiple regression models accounted for significant amounts of the variation in litter FFM. LFMC decreased with needle age and, for full-grown needles, was up to 25% (ODW) higher in shaded compared to unshaded canopy locations. Seasonal patterns of change in LFMC of full-grown needles were not well defined. Variation in the parameters and the precision of FFM regression relationships between fuel locations and stands with contrasting management demonstrate the site specificity and limitations of empirical FFM models. The results suggest that for prediction of aerial FFM, models based on a combination of T and H are most appropriate; while, models that include a soil moisture variable may predict FFM of litter fuels more accurately. However, the intrinsic variation in FFM revealed in this study indicates that such models, although providing a useful guide, may not predict FFM with the accuracy required for fire behaviour models during high fire danger weather - when fuel moistures are low.

THE EFFECT ON VARIATIONS IN DECAY OF MOISTURE CONTENT AND RATE OF GROWTH IN SUBALPINE SPRUCE

1958 ◽  
Vol 36 (1) ◽  
pp. 187-206 ◽  
Author(s):  
D. E. Etheridge
Keyword(s):  
Moisture Content ◽  
Laboratory Tests ◽  
Moisture Contents ◽  
Test Pieces ◽  
Significant Difference ◽  
Rate Of Decay ◽  
Laboratory Infection ◽  
Basal Portion ◽  
Understory Trees ◽  
Overstory Trees

The moisture content in subalpine spruce was highest in overstory trees and lowest in understory trees, and it was higher in trees on a moist site than in trees of similar vigor classes on a dry site. Moisture contents of 10% of saturation for the more vigorous trees on the moist site and 7% of saturation for the less vigorous trees on the dry site represented a statistically significant difference which appeared to restrict the development of heartwood fungi to the wetter trees. A similar difference in the moisture content existed between the 1.5-ft. and the 20-ft. level of the trees, the occurrence of fungi being restricted to the wetter basal portion of the stems. In the laboratory, infection did not take place in test blocks at moisture contents lower than 8% of saturation. It is suggested that the threshold moisture content for infection in the trees occurs around the 7 to 8% saturation level. In the laboratory tests a difference in the moisture content of 3.4% of saturation in wood resulted in a statistically significant difference in the rate of decay by Coniophora puteana (Schum. ex Fr.) Karst., but differences in ring frequency and specific gravity in the test pieces corresponding to the differences between these properties in the living trees did not appreciably affect the decay rate. There was no evidence that variations in the distribution of decay-promoting or decay-retarding substances occurred in the trees from the two sites.

The likelihood of ignition of dry-eucalypt forest litter by firebrands

2015 ◽  
Vol 24 (2) ◽  
pp. 225 ◽  
Author(s):  
P. F. M. Ellis
Keyword(s):  
Wind Speed ◽  
Moisture Content ◽  
Eucalyptus Globulus ◽  
Forest Litter ◽  
Fuel Moisture ◽  
Ignition Probability ◽  
Moisture Contents ◽  
Eucalypt Forest ◽  
Fuel Moisture Content ◽  
Practical Measure

Ignition probability of litter of dry-eucalypt forest by standard flaming and glowing firebrand samples was tested in a wind tunnel. Standard flaming firebrands were sections of bamboo sate stick 50 mm long, and flamed for ~9 s in still air. Standard glowing samples were sections of shed bark of Eucalyptus globulus 50 mm long, 15 mm wide and ~2 mm in thickness. These were burnt at their terminal velocities and at deposition had a mean mass of 0.2 g and would remain glowing for 2.5 min in wind. Ignition was tested using air speeds of zero, 1 and 2 m s–1, and oven-dried fuel moisture contents between 4 and 21%. For flaming samples, ignition probability was insensitive to variation in fuel and airflow characteristics and was a function of wind (no wind or wind) and fuel moisture content. For glowing samples, ignition probability was a function of fuel moisture content and wind speed. The models confirm the dominating influence of fuel moisture, are consistent with expert observations in the field and provide a practical measure of ignition likelihood by firebrands. It is argued that airflow turbulence and relative humidity are potentially significant for ignition by glowing firebrands.

The Smoulder Stream of Cigarettes / Zur Kenntnis des Glimmstromes von Cigaretten

1965 ◽  
Vol 3 (2) ◽  
Author(s):  
F. Seehofer ◽  
W. Schulz
Keyword(s):  
Moisture Content ◽  
Spatial Position ◽  
High Yield ◽  
Physical Conditions ◽  
Moisture Contents ◽  
Cigarette Paper ◽  
First Time

AbstractThe phenomenon of the smoulder stream flowing through the cigarette during smouldering and during the puff intervals is demonstrated for the first time and its dependence upon physical conditions is examined. The volume of the smoulder stream can amount up to 180 ml per cigarette. Increasing draw resistance of the cigarette and augmenting moisture content of the tobacco as well as perforation of the cigarette paper have a decreasing effect on volume and velocity of the smoulder stream. The porosity of the cigarette paper has no perceptible influence. The spatial position of the cigarette affects volume and velocity of the smoulder stream. The influence exercised by the smoulder stream on the yields of total condensate, nicotine, phenols, aldehydes, and acroleine when the cigarette tip is open during the puff intervals is determined. When the moisture contents of the tobacco were extremely high, yield decreases reaching 50 % could be observed.

Developing a Linearization Method to Determine Optimum Blending for Surimi with Varied Moisture Contents Using Linear Programming

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Hyeon W. Park ◽  
Jae W. Park ◽  
Won B. Yoon
Keyword(s):  
Linear Programming ◽  
Moisture Content ◽  
Standard Procedure ◽  
Unit Cost ◽  
Linearization Method ◽  
Model Parameters ◽  
Additional Information ◽  
Moisture Contents ◽  
Design Variables ◽  
Critical Moisture

AbstractNovel algorithm to determine the least cost formulation of a surimi blend was developed using linear programming (LP). Texture properties and the unit cost of surimi blend at the target moisture content were used as constraint functions and the objective function, respectively. The mathematical models to describe the moisture content dependence of the ring tensile properties were developed using critical moisture content, and the model parameters were used for the least cost LP (LCLP) model. The LCLP model successfully predicted the quality of surimi blend. Sensitivity analysis was used to obtain an additional information when the perturbations of design variables are provided. A standard procedure to determine the least cost formulation for blending surimi with varied moisture contents was systematically developed.

scholarly journals Experimental Study on the Softening Characteristics of Sandstone and Mudstone in Relation to Moisture Content

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Gui-chen Li ◽  
Chong-chong Qi ◽  
Yuan-tian Sun ◽  
Xiao-lin Tang ◽  
Bao-quan Hou
Keyword(s):  
Moisture Content ◽  
Vertical Displacement ◽  
Surface Porosity ◽  
Shear Tests ◽  
Moisture Contents ◽  
Dynamic Finite Element ◽  
Rock Types ◽  
Underground Roadway ◽  
The Stability ◽  
Kinetics Of

The kinetics of fluid-solid coupling during immersion is an important topic of investigation in rock engineering. Two rock types, sandstone and mudstone, are selected in this work to study the correlation between the softening characteristics of the rocks and moisture content. This is achieved through detailed studies using scanning electron microscopy, shear tests, and evaluation of rock index properties during exposure to different moisture contents. An underground roadway excavation is simulated by dynamic finite element modeling to analyze the effect of moisture content on the stability of the roadway. The results show that moisture content has a significant effect on shear properties reduction of both sandstone and mudstone, which must thus be considered in mining or excavation processes. Specifically, it is found that the number, area, and diameter of micropores, as well as surface porosity, increase with increasing moisture content. Additionally, stress concentration is negatively correlated with moisture content, while the influenced area and vertical displacement are positively correlated with moisture content. These findings may provide useful input for the design of underground roadways.

Effect of Bromus inermis Leyss Planting on Dynamic Changes of Soil Moisture Contents on the Bare Slope

2013 ◽  
Vol 807-809 ◽  
pp. 1648-1652
Author(s):  
Tie Jun Sun ◽  
Baderihu Tajilake
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Regulatory Mechanism ◽  
Dynamic Balance ◽  
Bromus Inermis ◽  
Dynamic Changes ◽  
Moisture Contents ◽  
Biological Characters ◽  
Underground Biomass

Experiment was executed to plant eco-grass of Bromus inermis Leyss on 15°bare slopes, and study effect of biological characters on dynamics of soil moisture contents. The results indicated that vegetation restored quickly on the bare slope after the eco-grass planted. There were 2473.4 kg/hm2 of overground biomass and 1744.1kg/hm2 of underground biomass, and 70% of underground biomass was in 0-10cm layer of soil. Meanwhile, there was a regulatory mechanism of soil moisture content for Bromus inermis Leyss. When rainfall was enough, soil moisture content in 0-80 cm layer could reach to the most of 26.83% quickly this year. Next it could decline near to the first value of 19.81% after rainfall stopped, and keep a dynamic balance between 19.48% and 19.96%. Moreover, the regulatory mechanism realized though underground biomass, and was clearer with underground biomass increasing, especially in the 0-40cm layer of soil.

Assessment of Moisture Content in Sandy Beach Environments from Multispectral Satellite Imagery

2021 ◽  
Author(s):  
Julie Paprocki ◽  
Nina Stark ◽  
Hans C Graber ◽  
Heidi Wadman ◽  
Jesse E McNinch
Keyword(s):  
Moisture Content ◽  
Laboratory Data ◽  
Field Measurements ◽  
Weather Conditions ◽  
Sandy Beaches ◽  
Percent Error ◽  
Moisture Contents ◽  
Multispectral Satellite Imagery ◽  
Factor C

A framework for estimating moisture content from satellite-based multispectral imagery of sandy beaches was tested under various site conditions and sensors. It utilizes the reflectance of dry soil and an empirical factor c relating reflectance and moisture content for specific sediment. Here, c was derived two ways: first, from in-situ measurements of moisture content and average NIR image reflectance; and second, from laboratory-based measurements of moisture content and spectrometer reflectance. The proposed method was tested at four sandy beaches: Duck, North Carolina, and Cannon Beach, Ocean Cape, and Point Carrew, Yakutat, Alaska. Both measured and estimated moisture content profiles were impacted by site geomorphology. For profiles with uniform slopes, moisture contents ranged from 3.0%-8.0% (Zone 1) and from 8.0%-23.0% (Zone 2). Compared to field measurements, the moisture contents estimated using c calibrated from in-situ and laboratory data resulted in percent error of 3.6%-44.7% and 2.7%-58.6%, respectively. The highest percent error occurred at the transition from Zone 1 to Zone 2. Generally, moisture contents were overestimated in Zone 1 and underestimated in Zone 2, but followed the expected trends based on field measurements. When estimated moisture contents in Zone 1 exceeded 10%, surface roughness, debris, geomorphology, and weather conditions were considered.

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