Sampling with probability proportional to prediction (3P sampling) using covariates derived from spherical images

2021 ◽  
pp. 1-8
Author(s):  
Yung-Han Hsu ◽  
John A. Kershaw ◽  
Mark J. Ducey ◽  
Ting-Ru Yang ◽  
Haozhou Wang
Keyword(s):  
Basal Area ◽  
Efficient Design ◽  
Two Phase ◽  
Large Samples ◽  
Spherical Images ◽  
Systematic Selection ◽  
Volume Estimates ◽  
Stand Conditions ◽  
Selection Of ◽  
Spherical Camera

Using a two-phase sampling approach with systematic selection of large samples of covariates followed by a sampling with probability proportional to prediction (3P sampling) process to subsample field measures of the parameters of interest can be an efficient design to sample larger forest areas. To assist in obtaining predictions for each sample plot consistently and rapidly, we propose using a 360° spherical camera. In this study, three covariates derived from spherical images were evaluated: (i) basal area (P[BA]); (ii) sum of squared heights per hectare (P[SHT]); and (iii) stem fraction (P[SF]). These covariates were used to estimate volume. Sample simulations showed no biases in volume estimates for any of the three covariates. Overall, P[SF] had the lowest standard error percentages across different simulated sample sizes (10% for five subsamples to 2.5% for 50 subsamples), even though it had the lowest correlations with field volume (correlation = 0.30–0.31). This may be a result of the relatively consistent stand conditions within the study site. Based on our results, standard errors of 5% were obtainable with measurement fractions of about 25% of the number of image-based predictions when using P[SF] or P[BA] and 75% when using P[SHT].

Biomass estimates derived from sector subsampling of 360° spherical images

2021 ◽  
Author(s):  
Xiao Dai ◽  
Mark J Ducey ◽  
Haozhou Wang ◽  
Ting-Ru Yang ◽  
Yung-Han Hsu ◽  
...  
Keyword(s):  
Basal Area ◽  
Sampling Errors ◽  
Eastern Canada ◽  
Individual Tree ◽  
Inventory Costs ◽  
Standard Error Estimation ◽  
The Mean ◽  
Biomass Ratio ◽  
Spherical Images ◽  
Additional Level

Abstract Efficient subsampling designs reduce forest inventory costs by focusing sampling efforts on more variable forest attributes. Sector subsampling is an efficient and accurate alternative to big basal area factor (big BAF) sampling to estimate the mean basal area to biomass ratio. In this study, we apply sector subsampling of spherical images to estimate aboveground biomass and compare our image-based estimates with field data collected from three early spacing trials on western Newfoundland Island in eastern Canada. The results show that sector subsampling of spherical images produced increased sampling errors of 0.3–3.4 per cent with only about 60 trees measured across 30 spherical images compared with about 4000 trees measured in the field. Photo-derived basal area was underestimated because of occluded trees; however, we implemented an additional level of subsampling, collecting field-based basal area counts, to correct for bias due to occluded trees. We applied Bruce’s formula for standard error estimation to our three-level hierarchical subsampling scheme and showed that Bruce’s formula is generalizable to any dimension of hierarchical subsampling. Spherical images are easily and quickly captured in the field using a consumer-grade 360° camera and sector subsampling, including all individual tree measurements, were obtained using a custom-developed python software package. The system is an efficient and accurate photo-based alternative to field-based big BAF subsampling.

Systematic selection of field response measurements for excavation back analysis

2021 ◽  
Vol 48 ◽  
pp. 101296
Author(s):  
Ze Zhou Wang ◽  
Numa Joy Bertola ◽  
Siang Huat Goh ◽  
Ian F.C. Smith
Keyword(s):  
Back Analysis ◽  
Field Response ◽  
Systematic Selection ◽  
Selection Of

Systematic selection of microsatellite for paternity testing of yak

2021 ◽  
Author(s):  
Tong Chen ◽  
Ruilin Zeng ◽  
Wenyi Cai ◽  
Xianrong Xiong ◽  
Wei Fu ◽  
...  
Keyword(s):  
Paternity Testing ◽  
Systematic Selection ◽  
Selection Of

Combining computational and experimental approaches to select chromophores to enable the detection of fatty acids via HPLC

2019 ◽  
Vol 11 (23) ◽  
pp. 2952-2959 ◽  
Author(s):  
Jessica Pandohee ◽  
Robert J. Rees ◽  
Michelle J. S. Spencer ◽  
Aaron Raynor ◽  
Oliver A. H. Jones
Keyword(s):  
Fatty Acids ◽  
Quantum Mechanics ◽  
Chemical Reaction ◽  
Experimental Approaches ◽  
Systematic Selection ◽  
Selection Of

This paper outlines a protocol, which combines quantum mechanics calculations and experimental synthesis, to enable systematic selection of suitable chromophores based on their stability of fluorescence and efficiency of the chemical reaction.

Systematic selection of software architecture styles

IET Software ◽  
2010 ◽  
Vol 4 (5) ◽  
pp. 349 ◽  
Author(s):  
M. Galster ◽  
A. Eberlein ◽  
M. Moussavi
Keyword(s):  
Software Architecture ◽  
Systematic Selection ◽  
Selection Of

Numerical Solution of the Two-Phase Stefan Problem in the Enthalpy Formulation with Smoothing the Coefficients

2021 ◽  
pp. 4-23
Author(s):  
V.I. Vasilyev ◽  
M.V. Vasilyeva ◽  
S.P. Stepanov ◽  
N.I. Sidnyaev ◽  
O.I. Matveeva ◽  
...  
Keyword(s):  
Numerical Solution ◽  
Stefan Problem ◽  
Large Diameter ◽  
Discontinuous Coefficients ◽  
Numerical Calculations ◽  
Smooth Functions ◽  
Two Phase ◽  
Time Layer ◽  
Dirac Delta ◽  
Selection Of

To simulate heat transfer processes with phase transitions, the classical enthalpy model of Stefan is used, accompanied by phase transformations of the medium with absorption and release of latent heat of a change in the state of aggregation. The paper introduces a solution to the two-phase Stefan problem for a one-dimensional quasilinear second-order parabolic equation with discontinuous coefficients. A method for smearing the Dirac delta function using the smoothing of discontinuous coefficients by smooth functions is proposed. The method is based on the use of the integral of errors and the Gaussian normal distribution with an automated selection of the value of the interval of their smoothing by the desired function (temperature). The discontinuous coefficients are replaced by bounded smooth temperature functions. For the numerical solution, the finite difference method and the finite element method with an automated selection of the smearing and smoothing parameters for the coefficients at each time layer are used. The results of numerical calculations are compared with the solution of Stefan’s two-phase self-similar problem --- with a mathematical model of the formation of the ice cover of the reservoir. Numerical simulation of the thawing effect of installing additional piles on the existing pile field is carried out. The temperature on the day surface of the base of the structure is set with account for the amplitude of air temperature fluctuations, taken from the data of the Yakutsk meteorological station. The study presents the results of numerical calculations for concrete piles installed in the summer in large-diameter drilled wells using cement-sand mortars with a temperature of 25 °С. The distributions of soil temperature are obtained for different points in time

Development and Implementation of Shape Comparison of 3D CAD Models

2009 ◽  
Author(s):  
Sagar Chowdhury ◽  
Zahed Siddique
Keyword(s):  
Computer Hardware ◽  
Efficient Design ◽  
User Friendliness ◽  
Specialized Knowledge ◽  
3D Cad ◽  
Large Databases ◽  
Modeling Software ◽  
Cad Models ◽  
Near Future ◽  
Selection Of

With the advancements of 3D modeling software, the use of CAD in design has become a standard practice. In recent years development in computer hardware and improvements in user friendliness of the CAD software has allowed designers to quickly and easily modify the CAD models. This modification capability allows CAD to be an integral part of the design process. Due to the increase in global competition, companies have become increasingly interested in fast and efficient design processes. One way to achieve improved efficiency is through better collaboration among designers working in common or similar projects and disciplines. A large design problem often requires specialized knowledge from several fields. Collaboration among the designers from these fields will ensure efficient design. Interaction among the designers can prevent redesign of similar components/subsystems, which requires the ability to share their designs. With the increase of collaboration, designers can now get access to large databases of 3D CAD models. But the challenge lies in search capabilities to identify common models from a large database. These considerations suggest that in the near future a challenge in 3D CAD industry will be how to find models of similar components and products. This paper presents an approach and its implementation to measure the similarity among a number of CAD models. The approach is based on the extraction and organization of information from the CAD models, which is followed by the suitable selection of commonality index and calculation of the commonality among a set of CAD models. A set of Vacuum cleaners are modeled and then compared to demonstrate the application of the approach.

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