scholarly journals Comparison of different methods for the in situ measurement of forest litter moisture content

2015 ◽  
Vol 3 (6) ◽  
pp. 3733-3760 ◽  
Author(s):  
C. Schunk ◽  
B. Ruth ◽  
M. Leuchner ◽  
C. Wastl ◽  
A. Menzel
Keyword(s):  
Moisture Content ◽  
Fire Behavior ◽  
Forest Litter ◽  
Fire Season ◽  
Drought Period ◽  
Mean Values ◽  
Installation Effects ◽  
Standard Deviations ◽  
Reference Measurements

Abstract. Dead fine fuel (e.g. litter) moisture content is an important parameter for both forest fire and ecological applications as it is related to ignitability, fire behavior as well as soil respiration. However, the comprehensive literature review in this paper shows that there is no easy-to-use method for automated measurements available. This study investigates the applicability of four different sensor types (permittivity and electrical resistance measuring principles) for this measurement. Comparisons were made to manual gravimetric reference measurements carried out almost daily for one fire season and overall agreement was good (highly significant correlations with 0.792 ≦ r ≦ 0.947). Standard deviations within sensor types were linearly correlated to daily sensor mean values; however, above a certain threshold they became irregular, which may be linked to exceedance of the working ranges. Thus, measurements with irregular standard deviations were considered unusable and calibrations of all individual sensors were compared for useable periods. A large drift in the sensor raw value-litter moisture-relationship became obvious from drought to drought period. This drift may be related to installation effects or settling and decomposition of the litter layer throughout the fire season. Because of the drift and the in situ calibration necessary, it cannot be recommended to use the methods presented here for monitoring purposes. However, they may be interesting for scientific studies when some manual fuel moisture measurements are made anyway. Additionally, a number of potential methodological improvements are suggested.

scholarly journals Comparison of different methods for the in situ measurement of forest litter moisture content

2016 ◽  
Vol 16 (2) ◽  
pp. 403-415 ◽  
Author(s):  
C. Schunk ◽  
B. Ruth ◽  
M. Leuchner ◽  
C. Wastl ◽  
A. Menzel
Keyword(s):  
Moisture Content ◽  
Fire Behavior ◽  
Fire Risk ◽  
Forest Litter ◽  
Fire Season ◽  
Drought Period ◽  
Hazard Management ◽  
Mean Values ◽  
Standard Deviations

Abstract. Dead fine fuel (e.g., litter) moisture content is an important parameter for both forest fire and ecological applications as it is related to ignitability, fire behavior and soil respiration. Real-time availability of this value would thus be a great benefit to fire risk management and prevention. However, the comprehensive literature review in this paper shows that there is no easy-to-use method for automated measurements available. This study investigates the applicability of four different sensor types (permittivity and electrical resistance measuring principles) for this measurement. Comparisons were made to manual gravimetric reference measurements carried out almost daily for one fire season and overall agreement was good (highly significant correlations with 0.792 <  =  r <  =  0.947, p  <  0.001). Standard deviations within sensor types were linearly correlated to daily sensor mean values; however, above a certain threshold they became irregular, which may be linked to exceedance of the working ranges. Thus, measurements with irregular standard deviations were considered unusable and relationships between gravimetric and automatic measurements of all individual sensors were compared only for useable periods. A large drift in these relationships became obvious from drought to drought period. This drift may be related to installation effects or settling and decomposition of the litter layer throughout the fire season. Because of the drift and the in situ calibration necessary, it cannot be recommended to use the methods presented here for monitoring purposes and thus operational hazard management. However, they may be interesting for scientific studies when some manual fuel moisture measurements are made anyway. Additionally, a number of potential methodological improvements are suggested.

scholarly journals Why is the Effect of Live Fuel Moisture Content on Fire Rate of Spread Underestimated in Field Experiments in Shrublands?

2018 ◽  
Author(s):  
Francois Pimont ◽  
Julien Ruffault ◽  
Nicolas Martin ◽  
Jean-Luc Dupuy
Keyword(s):  
Moisture Content ◽  
Field Experiments ◽  
Fire Behavior ◽  
Fire Season ◽  
Special Focus ◽  
Fuel Moisture ◽  
Power Functions ◽  
Random Measurement Error ◽  
Live Fuel Moisture ◽  
Fuel Moisture Content

Live fuel moisture content (LFMC) influences fire activity at landscape scale and fire behavior in laboratory experiments. However, field evidences linking LFMC to fire behavior are very limited despite numerous field experiments. In the present study, we reanalyze a shrubland fire dataset with a special focus on LFMC to explain this counterintuitive outcome. We found that this controversy might result from three reasons. First, the range of experimental LFMC &nbsp;data was too moist to reveal significant effect with the widespread exponential or power functions. Indeed, LFMC exhibited a strong effect below 100%, but marginal above this threshold, contrary to these functions. Second, we found that the LFMC significance was unlikely when the size of the dataset was smaller than 40. Finally, a complementary analysis suggested that 10 to 15% of random measurement error in variables could lead to an underestimation by 30&nbsp;% of the LFMC effect. The effect of LFMC in field experiments is thus stronger than previously reported in the range prevailing during the actual French fire season and in accordance with observations at different scales. This highlights the need to improve our understanding of the relationship between LFMC and fire behavior to refine fire danger predictions.

scholarly journals Reference Measurements in Developing UAV Systems for Detecting Pests, Weeds, and Diseases

2021 ◽  
Vol 13 (7) ◽  
pp. 1238
Author(s):  
Jere Kaivosoja ◽  
Juho Hautsalo ◽  
Jaakko Heikkinen ◽  
Lea Hiltunen ◽  
Pentti Ruuttunen ◽  
...  
Keyword(s):  
Reference Data ◽  
Measurement Techniques ◽  
Synthetic Data ◽  
Ground Truth ◽  
Precision Farming ◽  
Aerial Imaging ◽  
Aerial Vehicle ◽  
Uav Images ◽  
Reference Measurements

The development of UAV (unmanned aerial vehicle) imaging technologies for precision farming applications is rapid, and new studies are published frequently. In cases where measurements are based on aerial imaging, there is the need to have ground truth or reference data in order to develop reliable applications. However, in several precision farming use cases such as pests, weeds, and diseases detection, the reference data can be subjective or relatively difficult to capture. Furthermore, the collection of reference data is usually laborious and time consuming. It also appears that it is difficult to develop generalisable solutions for these areas. This review studies previous research related to pests, weeds, and diseases detection and mapping using UAV imaging in the precision farming context, underpinning the applied reference measurement techniques. The majority of the reviewed studies utilised subjective visual observations of UAV images, and only a few applied in situ measurements. The conclusion of the review is that there is a lack of quantitative and repeatable reference data measurement solutions in the areas of mapping pests, weeds, and diseases. In addition, the results that the studies present should be reflected in the applied references. An option in the future approach could be the use of synthetic data as reference.

scholarly journals Development of a rapid field testing method for metals in horizontal directional drilling residuals with XRF sensor

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hailin Zhang ◽  
João Antonangelo ◽  
Chad Penn
Keyword(s):  
Moisture Content ◽  
Standard Method ◽  
Field Testing ◽  
Field Method ◽  
Filter Press ◽  
Directional Drilling ◽  
Horizontal Directional Drilling ◽  
Excess Water ◽  
Spiked Soil

AbstractPortable X-ray fluorescence (pXRF) spectrometer allows fast in-situ elemental determination without wet digestion for soils or geological materials, but the use of XRF on wet materials is not well documented. Our objective was to develop a rapid field method using pXRF to measure metals in the residues from horizontal directional drilling (HDD) operations so that proper disposal decisions can be made in-situ. To establish the procedure, we spiked soil samples with 4 concentrations of Cr, Ni, Cu, Zn, As, Cd, and Pb up to 1000 mg kg−1, and then the metal concentrations were determined by wet chemical method after drying and acid digestion (standard method), and by pXRF, also at laboratory conditions, after drying and at two different moisture conditions. The measurements by pXRF and standard method after drying and after removal of excess water (AREW) were highly correlated with slopes ranging from 0.83 ± 0.01 to 1.08 ± 0.01 (P < 0.001) for all metals. The relationship was better AREW than the saturated paste without removal of excess water and the moisture content affected only the accuracy of As, Cd, and Pb. The procedure established was successfully used for HDD residues collected from 26 states of US with moisture content ranging from 14 to 83% AREW. The pXRF was proven to be a reliable tool for fast detection of common metals in dried soils and HDD residues, and samples containing < 30% moisture content without needing to correct for moisture. If the moisture is > 30%, excess water in samples need to be removed with a commercially available filter press to achieve high accuracy. The developed procedures reduce time of metal detection from days to about an hour which allows drilling operators to make quick decisions on soil or HDD disposal.

Municipal solid waste in situ moisture content measurement using an electrical resistance sensor

2003 ◽  
Vol 23 (7) ◽  
pp. 667-674 ◽  
Author(s):  
Nitin A. Gawande ◽  
Debra R. Reinhart ◽  
Philip A. Thomas ◽  
Philip T. McCreanor ◽  
Timothy G. Townsend
Keyword(s):  
Moisture Content ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Electrical Resistance ◽  
Content Measurement ◽  
Moisture Content Measurement

Pyrolysis of Hailar Lignite: Experiments with a Tubular Reactor and a Continuous Screw Kiln Reactor

2014 ◽  
Vol 672-674 ◽  
pp. 665-671
Author(s):  
Hao Jie Gao ◽  
Yue Zhao Zhu ◽  
Hai Jun Chen ◽  
Chuan Hua Liao ◽  
Yang Du ◽  
...  
Keyword(s):  
Moisture Content ◽  
Significant Influence ◽  
Tubular Reactor ◽  
Product Yield ◽  
Heating Process ◽  
Intermediate Products ◽  
Temperature Programmed ◽  
Gas Dilution ◽  
Pyrolysis Processes

Pyrolysis of Hailar lignite (moisture content ~ 34.81 wt%) was investigated at temperatures ranging from 700 °C to 900 °C in two different reactors: A tubular reactor (TR) and a continuous screw kiln reactor (CSKR). Under temperature programmed-heating conditions in the TR reactor, the auto-generated steam from the lignite moisture was vaporized and swept out of the reactor by the N2flow during the long heating process, leading to a weakened effect on the subsequent reactions. However, in the CSKR tests all the volatiles was generated continuously while avoid the carrier gas dilution , significant interactions between the in situ steam and the intermediate products occurred. Upon comparing the two pyrolysis processes, it was found the CSKR process exhibits higher H2yield of 23.23 mol/kg, H2proportion of 49.82 vol % than those (16.97 mol/kg, 41.51 vol %) from the TR process. The results demonstrated that inherent moisture in Hailar lignite had a significant influence on the product yield, depending on the pyrolysis conditions. It was also shown that increase in temperature led to rising dry gas yield and H2yield.

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.

scholarly journals Between-Country Comparability of Clinical Chemistry Results: An International Quality Assessment Survey of 17 Analytes in Six European Countries through Existing National Schemes

1993 ◽  
Vol 30 (3) ◽  
pp. 304-314 ◽  
Author(s):  
R T P Jansen ◽  
D G Bullock ◽  
A Vassault ◽  
H Baadenhuijsen ◽  
A De Leenheer ◽  
...  
Keyword(s):  
The Netherlands ◽  
Quality Assessment ◽  
Mutual Recognition ◽  
Clinical Chemistry ◽  
Reference Method ◽  
European Countries ◽  
Mean Values ◽  
Related Data ◽  
Standard Deviations ◽  
The Uk

Two lyophilized control sera were distributed through seven national external quality assessment schemes in six European countries—Belgium, Switzerland, France, The Netherlands, Sweden and the United Kingdom—participated in the study. The results for 17 routine analytes were obtained from almost 5000 laboratories for the two sera. The organizers of the schemes were asked to process the results according to a common outlier removal procedure, and submit method-related data if available. The two sera were also distributed through the external/internal scheme of The Netherlands, and the within-laboratory standard deviations calculated in this scheme have been used in a scaling procedure for the external mean values and between-laboratory standard deviations of the participating countries. The results show remarkable agreement in the national mean values for practically all analytes, but considerable differences in the between-laboratory variation. Data from comparable method groups was obtained for 12 analytes from Belgium, France, The Netherlands and the UK. Though revealing some specific differences between methods and countries, the method-related data are generally in agreement with the all-method data. In this study reference method values were only available for cholesterol. The high degree of agreement found suggests, however, that mutual recognition of all-method mean values in national schemes could be acceptable, especially for analytes for which reliable reference methods are not available. The major element of variation is between-laboratory rather than between-country.

Compressibility curves as a quantitative measure of soil tilth, II

1938 ◽  
Vol 28 (3) ◽  
pp. 367-378 ◽  
Author(s):  
G. W. Scott Blair ◽  
G. H. Cashen
Keyword(s):  
Moisture Content ◽  
Quantitative Measure ◽  
New Method ◽  
Complete Analysis

1. The method described in an earlier paper for measuring the compressibility of soils in situ has been used to study the gradual consolidation of soil following digging with a fork, and a new method in which the rate of flow of water through rubber tubes buried in the soil gives a measure of compression, is described.2. By means of this latter method some measure can be obtained of the changes that take place in the soil after it has been loaded and trampled.3. The results of the experiments confirm and amplify the earlier conclusions. Without further data it is hard to distinguish quantitatively the effects of moisture and time, but it is of interest that whereas the compressibility of newly dug soils is hardly affected by differences in moisture for the range of stress used, that of soils which have rested for some time since cultivation is much increased by an increase in moisture content.4. Experiments on a wider scale should be undertaken in order that a more complete analysis may be effected.

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