Estimating the accuracy of volume equations using taper equations of stem profile

1988 ◽  
Vol 18 (8) ◽  
pp. 1002-1007 ◽  
Author(s):  
Greg S. Biging
Keyword(s):  
Measurement Error ◽  
Simple Model ◽  
Numerical Technique ◽  
Total Error ◽  
Model Misspecification ◽  
Volume Estimation ◽  
White Fir ◽  
Taper Equations ◽  
Volume Equations ◽  
Selection Of

Comparisons of log volume estimation techniques are performed using the equations of Smalian, Huber, and Newton, and a numerical technique using cubic splines. The data utilized were obtained by predicting diameters at various points along the stem from two paper equations for white fir. Results indicate that Newton's and Huber's equations were the most accurate, followed by the cubic spline and Smalian's equation, respectively. This technique facilitated partitioning of the total error in volume estimation into measurement error and error due to model misspecification arising when the taper of logs could not be exactly described by a simple model such as a frustum of a paraboloid. For the taper relationships analyzed it was shown that the error due to the selection of an inappropriate mensurational model is less than 5% for a measurement distance of 16 ft (4.9 m) for all models tested and can be substantially reduced by applying the formulae only to logs positioned above basal swell. Systematic measurement error was assessed analytically and found to range between 1 and 4%. Thus, total error in volume estimation was less than 9% for all methods tested.

Guidelines for choosing volume equations in the presence of measurement error in height

2000 ◽  
Vol 30 (2) ◽  
pp. 306-310 ◽  
Author(s):  
M S Williams ◽  
H T Schreuder
Keyword(s):  
Measurement Error ◽  
Tree Species ◽  
Measurement Errors ◽  
Tree Diameter ◽  
Total Height ◽  
Volume Equations

Assuming volume equations with multiplicative errors, we derive simple conditions for determining when measurement error in total height is large enough that only using tree diameter, rather than both diameter and height, is more reliable for predicting tree volumes. Based on data for different tree species of excurrent form, we conclude that measurement errors up to ±40% of the true height can be tolerated before inclusion of estimated height in volume prediction is no longer warranted.

Dynamic Characterization of Brushless DC Motors and Propellers for Flight Applications

2017 ◽  
Vol 05 (03) ◽  
pp. 159-167 ◽  
Author(s):  
Dominic Muzar ◽  
Eric Lanteigne ◽  
Justin McLeod
Keyword(s):  
Simple Model ◽  
Brushless Dc Motor ◽  
Dynamic Characterization ◽  
Brushless Dc Motors ◽  
Brushless Dc ◽  
Dc Motors ◽  
Simple Motor ◽  
Aerial Vehicle ◽  
Selection Of

Although there exist a number of accurate unmanned aerial vehicle (UAV) thruster models, these models require the precise measurements of several motor and propeller characteristics. This paper presents a simple motor and propeller model that relies solely upon data provided by manufacturers. The model is validated by comparing theoretical motor and propeller behavior to experimental results obtained from thrust tests in a wind tunnel. The objective is to provide an accurate yet simple model to facilitate the selection of appropriate brushless DC motor and propeller combinations for flight applications.

scholarly journals Tilt error in cryospheric surface radiation measurements at high latitudes: a model study

2016 ◽  
Vol 10 (2) ◽  
pp. 613-622 ◽  
Author(s):  
Wiley Steven Bogren ◽  
John Faulkner Burkhart ◽  
Arve Kylling
Keyword(s):  
Measurement Error ◽  
Total Error ◽  
Surface Radiation ◽  
Cloud Optical Depth ◽  
Model Study ◽  
Tilt Error ◽  
Total Measurement Error ◽  
Spectral Ranges ◽  
Radiation Measurements

Abstract. We have evaluated the magnitude and makeup of error in cryospheric radiation observations due to small sensor misalignment in in situ measurements of solar irradiance. This error is examined through simulation of diffuse and direct irradiance arriving at a detector with a cosine-response fore optic. Emphasis is placed on assessing total error over the solar shortwave spectrum from 250 to 4500 nm, as well as supporting investigation over other relevant shortwave spectral ranges. The total measurement error introduced by sensor tilt is dominated by the direct component. For a typical high-latitude albedo measurement with a solar zenith angle of 60°, a sensor tilted by 1, 3, and 5° can, respectively introduce up to 2.7, 8.1, and 13.5 % error into the measured irradiance and similar errors in the derived albedo. Depending on the daily range of solar azimuth and zenith angles, significant measurement error can persist also in integrated daily irradiance and albedo. Simulations including a cloud layer demonstrate decreasing tilt error with increasing cloud optical depth.

Converting Volume Equations to Compatible Taper Equations

1972 ◽  
Vol 18 (3) ◽  
pp. 241-245 ◽  
Author(s):  
J. P. Demaerschalk
Keyword(s):  
Taper Equations ◽  
Volume Equations

scholarly journals Taper Equations for Five Major Commercial Tree Species in Manitoba, Canada

2007 ◽  
Vol 22 (3) ◽  
pp. 163-170 ◽  
Author(s):  
Ryan J. Klos ◽  
G. Geoff Wang ◽  
Qing-Lai Dang ◽  
Ed W. East
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Pinus Banksiana ◽  
White Spruce ◽  
Jack Pine ◽  
Volume Estimation ◽  
Trembling Aspen ◽  
Stem Form ◽  
Taper Equation ◽  
Taper Equations

Abstract Kozak's variable exponent taper equation was fitted for balsam poplar (Populus balsamifera L.), trembling aspen (Populus tremuloides Michx.), white spruce (Picea glauca [Moench] Voss), black spruce (Picea mariana [Mill.] B.S.P.), and jack pine (Pinus banksiana Lamb.) in Manitoba. Stem taper variability between two ecozones (i.e., Boreal Shield and Boreal Plains) were tested using the F-test. Regional differences were observed for trembling aspen, white spruce, and jack pine, and for those species, separate ecozone-specific taper equations were developed. However, the gross total volume estimates using the ecozone-specific equations were different from those of the provincial equations by only 2 percent. Although the regional difference in stem form was marginal within a province, a difference of approximately 7 percent of gross total volume estimation was found when our provincial taper equations were compared with those developed in Alberta and Saskatchewan. These results suggest that stem form variation increases with spatial scale and that a single taper equation for each species may be sufficient for each province.

Integrated Systems for the Estimation of Tree Taper and Volume

1973 ◽  
Vol 3 (1) ◽  
pp. 90-94 ◽  
Author(s):  
J. P. Demaerschalk
Keyword(s):  
Integrated Systems ◽  
Total Height ◽  
Breast Height ◽  
Taper Equations ◽  
Diameter Outside Bark ◽  
Volume Equations

The desirability and the advantages of deriving taper equations from existing volume equations are discussed. It is demonstrated that the most common types of volume equations can be converted to compatible taper equations. These mathematical stem profile expressions yield tree volumes for any desired stump height and top diameter outside bark from inputs of diameter breast height outside bark and total height.

An Assessment of White Spruce Tree Volume Equations in Canada

1990 ◽  
Vol 66 (6) ◽  
pp. 600-605 ◽  
Author(s):  
R. T. Morton ◽  
T. I. Grabowski ◽  
S. J. Titus ◽  
G. M. Bonnor
Keyword(s):  
Goodness Of Fit ◽  
White Spruce ◽  
Volume Estimation ◽  
Estimation Methods ◽  
Single Model ◽  
Variable Model ◽  
Fit Statistics ◽  
Volume Equations ◽  
Better Than

In 1985, a survey of nine provinces and two territories was conducted to summarize operational tree volume estimation methods. Based on those results, six tree volume estimation functions were evaluated to answer the question: can a single model be used nation-wide for tree volume estimation? The six models were fitted to nation-wide data for 980 white spruce trees distributed nearly equally among the provinces and territories. Based on goodness of fit statistics and analysis of residuals, Schumacher's (1933) model and the Quebec combined variable model performed marginally better than the others. Further, the analyses did not reveal any significant differences between territories and provinces. It appears that any of these models could be applied to broad regions of Canada without suffering significant losses in accuracy.

The sensitivity of measurement error in stand volume estimation

1990 ◽  
Vol 20 (6) ◽  
pp. 800-804 ◽  
Author(s):  
George Z. Gertner
Keyword(s):  
Measurement Error ◽  
Random Sample ◽  
Sampling Error ◽  
Regression Function ◽  
Volume Estimation ◽  
Simple Random Sample ◽  
Large Reduction ◽  
Stand Volume ◽  
Volume Function ◽  
Independent Variables

A method is given for approximating and evaluating the consequences of random and nonrandom errors in the independent variables of a nonlinear tree volume function that is used in the estimation of stand volume based on a simple random sample of plots. Sampling error, regression function error, and measurement error are accounted for with the method presented. An application is given where relatively moderate amounts of measurement error in the independent variables of a tree volume function can cause a relatively large reduction in the accuracy of estimated stand volume.

scholarly journals Evolutionary Selection of Individual Expectations and Aggregate Outcomes in Asset Pricing Experiments

2012 ◽  
Vol 4 (4) ◽  
pp. 35-64 ◽  
Author(s):  
Mikhail Anufriev ◽  
Cars Hommes
Keyword(s):  
Asset Pricing ◽  
Simple Model ◽  
Predictive Power ◽  
Experimental Setting ◽  
Price Behavior ◽  
Switching Model ◽  
Evolutionary Selection ◽  
Out Of Sample ◽  
Monotonic Convergence ◽  
Selection Of

In recent “learning to forecast” experiments (Hommes et al. 2005), three different patterns in aggregate price behavior have been observed: slow monotonic convergence, permanent oscillations, and dampened fluctuations. We show that a simple model of individual learning can explain these different aggregate outcomes within the same experimental setting. The key idea is evolutionary selection among heterogeneous expectation rules, driven by their relative performance. The out-of-sample predictive power of our switching model is higher compared to the rational or other homogeneous expectations benchmarks. Our results show that heterogeneity in expectations is crucial to describe individual forecasting and aggregate price behavior. (JEL C53, C91, D83, D84, G12)

Evaluation of Tensile Strength of Multistrand Conductors—Part I: Theoretical Basis

1998 ◽  
Vol 120 (1) ◽  
pp. 33-38 ◽  
Author(s):  
J. Lanteigne ◽  
A. Akhtar
Keyword(s):  
Tensile Strength ◽  
Simple Model ◽  
Theoretical Basis ◽  
Rotation Angle ◽  
Tensile Loading ◽  
Total Elongation ◽  
Plastic Behavior ◽  
Permanent Set ◽  
Selection Of

A simple model was developed to predict the plastic behavior of a stranded conductor under tensile loading to fracture. Two cases are considered; the torque transmitted in the case of conductors with fixed extremities and the rotation angle in the case of free rotating conductors. The permanent set caused by bending and torsion during the stranding process associated with conductor fabrication was taken into consideration. The model predicts maximum failing load and total elongation, parameters currently used for design and selection of conductors.

Sign in / Sign up

Export Citation Format

Share Document