Width of firebreak that is necessary to stop grass fires: some field experiments

1988 ◽  
Vol 18 (6) ◽  
pp. 682-687 ◽  
Author(s):  
Andrew A. G. Wilson
Keyword(s):  
Response Function ◽  
Field Experiments ◽  
Flame Length ◽  
Northern Territory ◽  
Forward Rate ◽  
Rate Of Spread ◽  
Practical Implications

Firebreaks were tested in the Northern Territory of Australia for their performance in halting the spread of 113 experimental grass fires burning in blocks which ranged from 1 to 4 ha in size. The widths of firebreak tested ranged from 1.5 to 15 m. The most intense of the fires burnt with a rate of spread of 1.9 m s−1 and had a fireline intensity of 17 MW m−1. The fastest fire stopped by a firebreak burnt with a forward rate of spread of 2.2 m s−1 and had a fireline intensity of 8 MW m−1. A logistic response function was fitted to the data on firebreak breach; this resulted in an equation for predicting the probability of firebreak breach. The probability of firebreak breach was found to increase with increasing fireline intensity and the presence of trees within 20 m of the firebreak and to decrease with increasing firebreak width. A published relationship between fireline intensity and flame length provided a sensible approximation to the width of firebreak that could be breached, via flame contact, by a fire of a given fireline intensity. Practical implications of the results are discussed.

“Please tidy up before leaving”: nudging Airbnb guests toward altruistic behavior

2019 ◽  
Vol 13 (4) ◽  
pp. 524-530 ◽  
Author(s):  
Paul Ranson ◽  
Daniel Guttentag
Keyword(s):  
Social Presence ◽  
Design Methodology ◽  
Field Experiments ◽  
Experimental Results ◽  
Altruistic Behavior ◽  
Content Type ◽  
The Social ◽  
Relationship Model ◽  
Social Market ◽  
Practical Implications

Purpose This study aimed to investigate whether increasing the social presence within an Airbnb lodging environment could nudge guests toward altruistic cleaning behaviors. Design/methodology/approach The study was based around a theoretical framework combining the social-market versus money-market relationship model, nudge theory and social presence theory. A series of three field experiments were conducted, in which social presence was manipulated to test its impact on guest cleaning behaviors prior to departure. Findings The experimental results confirmed the underlying hypothesis that an Airbnb listing’s enhanced social presence can subtly induce guests to help clean their rental units prior to departure. Originality/value This study is the first to examine behavioral nudging in an Airbnb context. It is also one of the first field experiments involving Airbnb. The study findings offer clear theoretical and practical implications.

scholarly journals The Impact of a Complement-Based Assortment Organization on Purchases

2019 ◽  
Vol 56 (3) ◽  
pp. 459-478 ◽  
Author(s):  
Panagiotis Sarantopoulos ◽  
Aristeidis Theotokis ◽  
Katerina Pramatari ◽  
Anne L. Roggeveen
Keyword(s):  
Virtual Reality ◽  
Field Experiments ◽  
Physical Characteristics ◽  
Lab Experiment ◽  
Product Categories ◽  
The Impact ◽  
Practical Implications

This article examines whether and why organizing product categories according to the consumption goal they serve (i.e., complement-based assortment organization) may increase purchases compared with organizing product categories according to their attributes or physical characteristics (i.e., substitute-based assortment organization). Across two field experiments, a virtual reality experiment, and a lab experiment, the authors show that a complement-based assortment organization, compared with a substitute-based assortment organization, leads to increased numbers of purchases and increased expenditures. Ease of visualization of the consumption process mediates the results. The impact of the complement-based organization on purchases is more pronounced for less involved consumers and for consumers with a less specific shopping goal. These findings have both theoretical and practical implications.

scholarly journals The reversal effect of prohibition signs

2011 ◽  
Vol 14 (5) ◽  
pp. 681-688 ◽  
Author(s):  
Kees Keizer ◽  
Siegwart Lindenberg ◽  
Linda Steg
Keyword(s):  
Field Experiments ◽  
Framing Theory ◽  
Public Places ◽  
Negative Norm ◽  
Support Mechanism ◽  
Reversal Effect ◽  
Goal Framing ◽  
Practical Implications

In public places one encounters many prohibition signs, as well as traces of the norm-violating behavior these signs are trying to reduce, like graffiti or litter. Based on goal framing theory and previous research, we argue that signs of (dis)respect of others for norms serve as norm-support cues which can weaken or strengthen the influence of norms. This norm-support mechanism implies that (traces of) norm violating behavior by others (i.e. negative norm-support cues) inhibit the influence of norms in general. We also hypothesize that making a known norm salient by means of a prohibition sign will not only focus people on this norm, but also on the corresponding (negative) norm-support cues in that particular situation, thereby enhancing the influence of these norm-support cues. Therefore, we expected that a prohibition sign placed in a setting with corresponding negative norm-support cues induces rather than reduces violations of the very same norm (i.e. same-norm reversal effect) and other norms (cross-norm reversal effect). We report results of two (quasi) field experiments that support the negative norm-support mechanism as well as the reversal effect of prohibition signs when cues show noncompliance. These findings are not only intriguing but they have important and clear practical implications.

Nitrogen and phosphorus nutrition of dryland grain sorghum at Katherine, Northern Territory. 2. Effect of rate and source of phosphorus fertilizer

1978 ◽  
Vol 18 (93) ◽  
pp. 564 ◽  
Author(s):  
RJK Myers
Keyword(s):  
Field Experiments ◽  
Grain Sorghum ◽  
Northern Territory ◽  
Diammonium Phosphate ◽  
Yield Response ◽  
Growth Stages ◽  
Growth Responses ◽  
Triple Superphosphate ◽  
Monoammonium Phosphate ◽  
Nitrogen And Phosphorus

Field experiments were conducted at Katherine, Northern Territory, in 1970-71 and 1971 -72 to examine responses of dryland grain sorghum to applied phosphorus at different growth stages. In the first, the effect of rate of application up to 100 kg P ha-1 as triple superphosphate was investigated. Growth responses to phosphorus were noted from mid-elongation onwards, but the magnitude of response varied between seasons, being greater in the higher rainfall season 1970-71. Maximum yields of grain were 7730 kg ha-1 with 50 kg P ha-1 in 1970-71, and 4440 kg ha-1 with 100 kg P ha-1 in 1971-72, which were increases of 49 and 37 per cent respectively over the appropriate zero phosphorus treatment. These suggested an increased requirement for phosphorus over previous recommendations. Phosphorus reduced the time from emergence to anthesis from 68 to 60 and from 70 to 63 days respectively in the two seasons. About half of the plant phosphorus was taken up after anthesis. It was concluded from soil analysis that phosphate-treated plots had an enhanced supply of phosphorus throughout the period of crop growth. In the second study, four phosphorus sources (superphosphate, triple superphosphate, monoammonium phosphate, and diammonium phosphate) were compared. With 25 kg P ha-1 and with constant nitrogen, grain yield response followed the order superphosphate > monoammonium phosphate > diammonium phosphate > triple superphosphate in both years. Triple superphosphate tended to give lower dry matter yields and nitrogen and phosphorus concentrations than the other three sources.

Nitrogen and phosphorus nutrition of dryland grain sorghum at Katherine, Northern Territory. 1. Effect of rate of nitrogen fertilizer

1978 ◽  
Vol 18 (93) ◽  
pp. 554 ◽  
Author(s):  
RJK Myers
Keyword(s):  
Nitrogen Fertilizer ◽  
Field Experiments ◽  
Nitrogen Concentration ◽  
Balance Sheet ◽  
Grain Sorghum ◽  
Northern Territory ◽  
Grain Weight ◽  
Nitrogen And Phosphorus ◽  
Nitrogen Response ◽  
Applied Nitrogen

Responses of dryland grain sorghum to applied nitrogen were examined in three field experiments at Katherine, Northern Territory, in 1969-70, 1970-71 and 1971-72. Rates of nitrogen up to 89 kg ha-1 in the first season and up to 200 kg ha-1 in subsequent seasons were used. The crops were sampled at floral initiation, mid-elongation, anthesis, and maturity. The three growing seasons were rated as below average, above average and average, respectively, for grain sorghum production. Nitrogen response was strongly season-dependent, Maximum yields (adjusted to 14 per cent moisture) were: 1969-70, 2280 kg ha-1, with 22.4 kg N ha-1 applied (with lower yields at higher rates of nitrogen) ; 1970-71,7730 kg ha-1 with 150 kg N ha-1 applied; and 1971-72,4440 kg ha-1 with 200 kg N ha-1 applied. These represented increases of 6, 50, and 62 per cent, respectively, over the zero nitrogen treatments. Applied nitrogen increased grain numbers per head and individual grain weight, but had no significant effect on head numbers. Applied nitrogen increased yields of nitrogen and phosphorus in plant material, and increased nitrogen concentration in plant parts. Apparent recoveries of nitrogen fertilizer ranged from 0 to 40 per cent, depending on year and rate applied. An approximate balance sheet suggested substantial losses from the mineral nitrogen pool in 1970- 71, a year of above average rainfall. Significant interactions between nitrogen and phosphorus fertilizer occurred only with grains per head and thousand grain weight.

scholarly journals The effect of ignition protocol on grassfire development

2020 ◽  
Vol 29 (1) ◽  
pp. 70
Author(s):  
Duncan Sutherland ◽  
Jason J. Sharples ◽  
Khalid A. M. Moinuddin
Keyword(s):  
Wind Speed ◽  
Temporal Resolution ◽  
Line Length ◽  
Forward Rate ◽  
High Temporal Resolution ◽  
Quasi Equilibrium ◽  
Rate Of Spread ◽  
Straight Line ◽  
Shortest Distance ◽  
Physics Based Simulation

The effect of ignition protocol on the development of grassfires is investigated using physics-based simulation. Simulation allows measurement of the forward rate of spread of a fire as a function of time at high temporal resolution. Two ignition protocols are considered: the inward ignition protocol, where the ignition proceeds in a straight line from the edges of the burnable fire plot to the centre of the plot; and the outwards ignition protocol, where the ignition proceeds from the centre of the burnable fire plot to the edges of the plot. In addition to the two ignition protocols, the wind speed, time taken for the ignition to be completed and ignition line length are varied. The rate of spread (R) of the resultant fires is analysed. The outwards ignition protocol leads to an (approximately) monotonic increase in R, whereas the inward ignition protocol can lead to a peak in R before decreasing to the quasi-equilibrium R. The fires simulated here typically take 50m from the ignition line to develop a quasi-equilibrium R. The results suggest that a faster ignition is preferable to achieve a quasi-equilibrium R in the shortest distance from the ignition line.

scholarly journals Evaluating the 10% wind speed rule of thumb for estimating a wildfire's forward rate of spread against an extensive independent set of observations

2020 ◽  
Vol 133 ◽  
pp. 104818
Author(s):  
Miguel G. Cruz ◽  
Martin E. Alexander ◽  
Paulo M. Fernandes ◽  
Musa Kilinc ◽  
Ângelo Sil
Keyword(s):  
Wind Speed ◽  
Independent Set ◽  
Forward Rate ◽  
Rule Of Thumb ◽  
Rate Of Spread

Weed Response, Yield, and Economics of Hexazinone and Nitrogen use in Lowbush Blueberry Production

Weed Science ◽  
1986 ◽  
Vol 34 (5) ◽  
pp. 723-729 ◽  
Author(s):  
David E. Yarborough ◽  
John J. Hanchar ◽  
Steven P. Skinner ◽  
Amr A. Ismail
Keyword(s):  
Response Function ◽  
Field Experiments ◽  
Function Analysis ◽  
Block Design ◽  
Growth And Yield ◽  
Net Income ◽  
Partial Budgeting ◽  
Lowbush Blueberry ◽  
Plant Stand ◽  
Effect On Yield

Field experiments designed to determine the efficacy and interaction of hexazinone [(3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione] and nitrogen on weeds and lowbush blueberry [Vaccinium angustifolium (Ait.)] growth and yield were established at five locations in 1980 and 13 locations in 1981. Hexazinone was applied after pruning, preemergence with nitrogen, using a split-block design, with locations serving as replications. Grasses, goldenrod (Solidago spp.), and meadowsweet [Spiraea latifolia (Ait.) Borkh. # SPVLF] were reduced significantly as the rate of hexazinone was increased. Blueberry injury, plant stand, number of flower buds, and yield all increased with increases in hexazinone rate. Variations in blueberry yields occurred among locations due to differences in plant stand and productivity, as well as climatic and edaphic factors. Within each nitrogen rate, increases in the rate of hexazinone resulted in a quadratic increase in blueberry yield. Within the hexazinone treatments, increasing nitrogen had no effect on yield. Blueberry yield reached a maximum of 3926 kg/ha at a hexazinone rate of 1.83 kg/ha. Partial budgeting was used to evaluate the effect of combinations of hexazinone and nitrogen on net income. Response function analysis determined yield and profit-maximizing combinations of hexazinone and nitrogen. Partial budgeting indicated that hexazinone alone or combined with nitrogen increased net income, but nitrogen without hexazinone decreased net income. Response function analysis indicated that hexazinone at 1.79 kg/ha without nitrogen maximized profits.

Behaviour and effects of prescribed fire in masticated fuelbeds

2011 ◽  
Vol 20 (8) ◽  
pp. 932 ◽  
Author(s):  
Eric E. Knapp ◽  
J. Morgan Varner ◽  
Matt D. Busse ◽  
Carl N. Skinner ◽  
Carol J. Shestak
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Tree Mortality ◽  
Fire Hazard ◽  
Weather Conditions ◽  
Flame Length ◽  
Fire Behaviour ◽  
Prescribed Burns ◽  
Rate Of Spread ◽  
Fuel Models

Mechanical mastication converts shrub and small tree fuels into surface fuels, and this method is being widely used as a treatment to reduce fire hazard. The compactness of these fuelbeds is thought to moderate fire behaviour, but whether standard fuel models can accurately predict fire behaviour and effects is poorly understood. Prescribed burns were conducted in young ponderosa pine (Pinus ponderosa Laws.) forests at two sites in northern California where the midstorey layer dominated by shrubs had been masticated. Surface fuels were raked from the base of a subset of trees before burning. Rate of spread and flame length were estimated for both backing and heading fires, soil heating measured with thermocouples and tree fire injury recorded. Standard fuel models often over-predicted rate of spread or under-predicted flame length. Custom models generally provided a better balance between the slow rates of spread and moderate flame lengths observed in prescribed burns. Post-fire tree mortality was most strongly associated with crown scorch and tree size; raking fuels from the base of trees did not improve survival. Under severe fire weather conditions, fire behaviour and effect models as well as observations from wildfires suggest that mastication may be more effective for moderating fire behaviour than reducing residual tree mortality. Treating masticated fuels with prescribed burns could potentially improve the resilience of stands to wildfire.

Fire spread in chaparral – a comparison of laboratory data and model predictions in burning live fuels

2016 ◽  
Vol 25 (9) ◽  
pp. 980 ◽  
Author(s):  
David R. Weise ◽  
Eunmo Koo ◽  
Xiangyang Zhou ◽  
Shankar Mahalingam ◽  
Frédéric Morandini ◽  
...  
Keyword(s):  
Laboratory Data ◽  
Slope Angle ◽  
Fire Spread ◽  
Flame Length ◽  
Important Variable ◽  
Rate Of Spread ◽  
Model Predictions ◽  
Physically Based ◽  
Live Fuels ◽  
Physically Based Models

Fire behaviour data from 240 laboratory fires in high-density live chaparral fuel beds were compared with model predictions. Logistic regression was used to develop a model to predict fire spread success in the fuel beds and linear regression was used to predict rate of spread. Predictions from the Rothermel equation and three proposed changes as well as two physically based models were compared with observed spread rates of spread. Flame length–fireline intensity relationships were compared with flame length data. Wind was the most important variable related to spread success. Air temperature, live fuel moisture content, slope angle and fuel bed bulk density were significantly related to spread rate. A flame length–fireline intensity model for Galician shrub fuels was similar to the chaparral data. The Rothermel model failed to predict fire spread in nearly all of the fires that spread using default values. Increasing the moisture of extinction marginally improved its performance. Modifications proposed by Cohen, Wilson and Catchpole also improved predictions. The models successfully predicted fire spread 49 to 69% of the time. Only the physical model predictions fell within a factor of two of actual rates. Mean bias of most models was close to zero. Physically based models generally performed better than empirical models and are recommended for further study.

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