scholarly journals Modelling Marten (Martes americana) Movement Costs in a Boreal Forest: Effects of Grain Size and Thematic Resolution

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Ophélie Planckaert ◽  
André Desrochers
Keyword(s):  
Grain Size ◽  
Model Performance ◽  
Null Model ◽  
Martes Americana ◽  
Landscape Resistance ◽  
Mature Forest ◽  
Thematic Resolution ◽  
Point Data ◽  
Cost Paths ◽  
Better Than

We investigated landscape resistance to movements of American marten (Martes americana) based on snow-tracking data. We generated movement cost maps of the study area with different grain size, thematic resolution, and habitat-specific resistance to movements. We compared simulated tracks obtained from resistance maps to real tracks plotted along transects that we surveyed in winters 2004 to 2008 at the Montmorency Forest, Quebec, Canada. Simulated tracks were located at the intersection between least-cost paths simulated across the study area and transects. We used nearest-neighbour distances between simulated and real tracks to assess the performance of resistance maps and estimate landscape resistance parameters. Simulations with specified costs to movement for open areas, young forest, and mature forest performed better than simpler resistance scenarios, suggesting that resistance to marten movements differed among those landscape attributes that were considered. Simulations with a map grain size of 100 m performed significantly better than 5, 25, and 300 m, possibly because of gap crossing avoidance. Model performance (compared to null model) was maximal when resistance to movement in open habitat was set to 20 times higher than in mature forest, but uncertainty around this estimate was large. This research demonstrates that presence-only (point) data can be used to parameterize movements using spatially explicit modelling.

General Models for Automated Essay Scoring: Exploring an Alternative to the Status Quo

2005 ◽  
Vol 33 (1) ◽  
pp. 101-113 ◽  
Author(s):  
P. Adam Kelly
Keyword(s):  
Empirical Evidence ◽  
Writing Assessment ◽  
Model Performance ◽  
Status Quo ◽  
Automated Essay Scoring ◽  
The Status ◽  
Essay Scoring ◽  
Better Than

Powers, Burstein, Chodorow, Fowles, and Kukich (2002) suggested that automated essay scoring (AES) may benefit from the use of “general” scoring models designed to score essays irrespective of the prompt for which an essay was written. They reasoned that such models may enhance score credibility by signifying that an AES system measures the same writing characteristics across all essays. They reported empirical evidence that general scoring models performed nearly as well in agreeing with human readers as did prompt-specific models, the “status quo” for most AES systems. In this study, general and prompt-specific models were again compared, but this time, general models performed as well as or better than prompt-specific models. Moreover, general models measured the same writing characteristics across all essays, while prompt-specific models measured writing characteristics idiosyncratic to the prompt. Further comparison of model performance across two different writing tasks and writing assessment programs bolstered the case for general models.

Effect of Hf Content on Oxidation Resistance of Single Crystal Superalloy at 1000°C

2014 ◽  
Vol 915-916 ◽  
pp. 562-566 ◽  
Author(s):  
Z.X. Shi ◽  
Shi Zhong Liu ◽  
M. Han ◽  
J.R. Li
Keyword(s):  
Grain Size ◽  
Single Crystal ◽  
Oxide Scale ◽  
Oxide Layer ◽  
Oxidation Resistance ◽  
Isothermal Oxidation ◽  
Single Crystal Superalloy ◽  
Ambient Atmosphere ◽  
Directionally Solidified ◽  
Better Than

The specimens of single crystal superalloy DD6 with 0.10% Hf and 0.47% Hf were prepared in the directionally solidified furnace. The effect of Hf content on the isothermal oxidation resistance of the second generation single crystal superalloy DD6 was studied at 1000°Cin ambient atmosphere. Morphology of oxides was examined by SEM, and their composition was analyzed by XRD and EDS. The experimental results show that the oxidation resistance of DD6 alloy with 0.47% Hf is better than that of the alloy with 0.10% Hf. The alloy with different Hf content all obeys parabolic rate law during oxidation for 100h at 1000°C. The increase of Hf content can promote the Al2O3 formation and decreases the proportion of NiO. The oxide grain size and the thickness of the oxide layer all reduce with increasing of Hf content. The oxide scale of the alloy with different Hf content is made up of an outer NiO layer with a small amount of Co3O4, inner Al2O3 and Cr2O3 layer with a small amount of TaO2.

Modeling Wood Density of Larch Using Random Effects Models

2013 ◽  
Vol 302 ◽  
pp. 124-127
Author(s):  
Yin Bang Liu ◽  
Li Chun Jiang
Keyword(s):  
Wood Density ◽  
Mixed Model ◽  
Model Performance ◽  
Polynomial Equation ◽  
Ordinary Least Squares ◽  
Mixed Effects ◽  
Water Displacement ◽  
Random Effects Models ◽  
Relative Errors ◽  
Better Than

Wood density samples were collected from dahurian larch (Larix gmelinii Rupr.) trees grown in northeastern China. Six discs (about 5 cm thick) were cut from each tree (i.e. from the root stem, at breast height (1.3m), and at 20%, 40%, 60%, and 80% of the total height). For each disc, a thick sliver with parallel sides was cut out along the diameter of the disc. The sliver was about 40-mm thick, with the pith located in the middle. Eight small pieces were cut from the sliver with equal distance from pith to bark. Wood density of small piece was obtained using water displacement method. A second order polynomial equation with linear mixed-effects was used for modeling wood density. The LME procedure in S-Plus is used to fit the mixed-effects models for the wood density data. The results showed that the polynomial model with three random parameters could significantly improve the model performance. The fitted mixed-effects model was also evaluated using a separate dataset. The mixed model was found to predict wood density better than the original model fitted using ordinary least-squares based on absolute and relative errors.

Abstract 31: Prediction of coronary artery and abdominal aortic calcium in middle-aged adults using the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) risk score: the CARDIA study

Circulation ◽  
2014 ◽  
Vol 129 (suppl_1) ◽  
Author(s):  
Christopher Prendergast ◽  
Jamal S Rana ◽  
Alex McMahan ◽  
Henry McGill ◽  
Jeff Carr ◽  
...  
Keyword(s):  
Risk Factors ◽  
Young Adults ◽  
Coronary Artery ◽  
Risk Score ◽  
Model Performance ◽  
Baseline Risk ◽  
Risk Scores ◽  
Abdominal Aortic ◽  
Point Increase ◽  
Better Than

Background: Risk scores to predict coronary and abdominal atherosclerosis have been developed from autopsy specimens from the right coronary artery and descending aorta and risk factors measured post-mortem in the Pathobiological Determinants of Atherosclerosis in Youth Study (PDAY), cohort aged 15-34 years. While the PDAY risk score predicts coronary artery calcium (CAC) up to 15 years before its assessment in Coronary Artery Risk Development in Young Adults (CARDIA), the clinical validity at 25 years follow up and of the abdominal score to predict abdominal aortic calcium (AAC) has not been tested. Objectives: To test the hypotheses: 1) PDAY risk scores at CARDIA baseline (cohort aged 18-30 years) predict CAC and abdominal aortic calcium (AAC) at year 25 better than PDAY risk scores measured at subsequent time points. 2) Change in risk over time will improve associations in Aim 1. Methods: The CARDIA study assessed CAC and AAC by computed tomography in young adults participating at year 25. The PDAY risk score was calculated from risk factors measured at the CARDIA examinations at years 0 (cohort aged 18-30 years), 5, 10, 15 and 25 (age 43-55 years). Results: Age and gender independent PDAY risk scores increased from CARDIA year 0 to year 25 (coronary from 1.80 to 4.95, abdomen from 1.88 to 3.18). Prevalence of any CAC was 28% and AAC was 53%. For a one point increase in risk score, baseline risk predicted CAC and AAC better than year 25 risk; change in risk improved the prediction further (Table). C-statistics for CAC prediction were higher at year 0 but similar at years 0 and 25 for AAC. Further analyses using PDAY scores calculated at 5 year intervals prior to the CT scan confirmed that CAC at baseline and AAC at year 5 had the highest Odds Ratios for a one point increase in score (AAC year 5 Odds Ratio 1.35 (1.30-1.41)). Conclusions: PDAY risk scores, applied to living adults in the CARDIA study, predicted CAC and AAC in 43-55 year old adults; including change in risk slightly improves model performance.

Paleoenvironmental context of the evolution of the Baodun Culture at Chengdu Plain, Sichuan Province, China

The Holocene ◽  
2019 ◽  
Vol 29 (11) ◽  
pp. 1731-1742 ◽  
Author(s):  
Ming Huang ◽  
Cheng Zhu ◽  
Chunmei Ma ◽  
Kunyu He ◽  
Jiajia Xu
Keyword(s):  
Grain Size ◽  
Climatic Conditions ◽  
Alluvial Fan ◽  
Human Migration ◽  
Cultural Groups ◽  
Hydrothermal Conditions ◽  
Chengdu Plain ◽  
Minjiang River ◽  
Archeological Evidence ◽  
Better Than

The Baodun Culture (4600–3700 a BP) is currently the earliest archeological culture found at the Chengdu Plain in southwestern China. Archeological evidence has shown that the Baodun Culture likely originated from the upper reaches of the Minjiang River, with two possible routes for human migration into the lower Chengdu Plain proposed: (1) At about 5000 a BP, favorable climatic conditions in the upper reaches of the Minjiang stimulated the growth of populations and the development of agriculture in the region. Due to this shift, some groups expanded from the upper Minjiang River to sites in the northern area of the Chengdu Plain, such as the Guiyuanqiao site; (2) during 4800–4300 a BP, a drying event occurred in the upper regions of the river valley causing a reduction in agricultural harvests and the migration of populations into sites – including the Baodun site – from this area of the Minjiang to the southwest piedmont of the Chengdu Plain. A multi-facetted study of the T3321 profile at Baodun site, including pollens, grain size, and geochemistry, demonstrates that after 6000 a BP, the climate of the Chengdu Plain shifted from cool, toward warmer and dryer conditions. However, as the Chengdu Plain is located in an alluvial fan, hydrothermal conditions here are still generally better than those in the upper reaches of Minjiang River. A change in the proportion of Concentricystes seen in the profile T3321 also indicates that after 4700 a BP, the lake and marsh areas associated with the Baodun site further decreased. However, as a result of this reduction, more terrestrial surfaces were exposed, providing favored space for Baodun Cultural groups in the area of the site. Due to such conditions, by about 4600 cal. a BP, people in the upper reaches of the Minjiang River had primarily moved to the southwest piedmont regions of the Chengdu Plain.

scholarly journals Assessing the Uncertainties of Four Precipitation Products for Swat Modeling in Mekong River Basin

2019 ◽  
Vol 11 (3) ◽  
pp. 304 ◽  
Author(s):  
Xiongpeng Tang ◽  
Jianyun Zhang ◽  
Chao Gao ◽  
Gebdang Ruben ◽  
Guoqing Wang
Keyword(s):  
River Basin ◽  
Assessment Tool ◽  
Model Performance ◽  
Mekong River ◽  
Distributed Hydrological Model ◽  
Parameter Uncertainties ◽  
Mekong River Basin ◽  
Daily Streamflow ◽  
Precipitation Estimates ◽  
Better Than

Using hydrological simulation to evaluate the accuracy of satellite-based and reanalysis precipitation products always suffer from a large uncertainty. This study evaluates four widely used global precipitation products with high spatial and temporal resolutions [i.e., AgMERRA (AgMIP modern-Era Retrospective Analysis for Research and Applications), MSWEP (Multi-Source Weighted-Ensemble Precipitation), PERSIANN-CDR (Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Climate Data Record), and TMPA (Tropical Rainfall Measuring Mission 3B42 Version7)] against gauge observations with six statistical metrics over Mekong River Basin (MRB). Furthermore, the Soil and Water Assessment Tool (SWAT), a widely used semi-distributed hydrological model, is calibrated using different precipitation inputs. Both model performance and uncertainties of parameters and prediction have been quantified. The following findings were obtained: (1) The MSWEP and TMPA precipitation products have good accuracy with higher CC, POD, and lower ME and RMSE, and the AgMERRA precipitation estimates perform better than PERSIANN-CDR in this rank; and (2) out of the six different climate regions of MRB, all six metrics are worse than that in the whole MRB. The AgMERRA can better reproduce the occurrence and contributions at different precipitation densities, and the MSWEP has the best performance in Cwb, Cwa, Aw, and Am regions that belong to the low latitudes. (3) Daily streamflow predictions obtained using MSWEP precipitation estimates are better than those simulated by other three products in term of both the model performance and parameter uncertainties; and (4) although MSWEP better captures the precipitation at different intensities in different climatic regions, the performance can still be improved, especially in the regions with higher altitude.

Combining remote sensing and eddy covariance data to monitor the gross primary production of an estuarine wetland ecosystem in East China

2015 ◽  
Vol 17 (4) ◽  
pp. 753-762
Author(s):  
Mingquan Wu ◽  
Shakir Muhammad ◽  
Fang Chen ◽  
Zheng Niu ◽  
Changyao Wang
Keyword(s):  
Remote Sensing ◽  
Primary Production ◽  
Eddy Covariance ◽  
Gross Primary Production ◽  
Model Performance ◽  
Wetland Ecosystem ◽  
Wetland Ecosystems ◽  
New Model ◽  
Estuarine Wetland ◽  
Better Than

A new model performance better than the MODIS GPP product for wetland ecosystems was proposed and validated.

The effect of increased soil nitrogen associated with medic ley on the performance of a standard and a semi-dwarf wheat cultivar

1973 ◽  
Vol 13 (60) ◽  
pp. 63 ◽  
Author(s):  
CL Tuohey
Keyword(s):  
Grain Size ◽  
Soil Nitrogen ◽  
Harvest Index ◽  
Wheat Cultivar ◽  
The Other ◽  
Nitrogen Level ◽  
Plant Nitrogen ◽  
Dwarf Cultivar ◽  
Standard Cultivar ◽  
Better Than

Two cropping rotations of fallow-wheat and four years of barrel medic (Medicago truncatula) pasture were used to obtain two levels of soil total nitrogen on a grey clay at Longerenong College, Dooen, Victoria. A semi-dwarf cultivar, Mexico 120, and a standard cultivar, Olympic, were then compared at the two levels of soil nitrogen over four years from 1964 to 1967. Mexico 120 outyielded Olympic by 1490 kg ha-1 in 1964 at the higher soil nitrogen level; however, it did not yield any better than Olympic at low soil nitrogen in that year nor at either soil nitrogen level in the other years. Mexico 120 had higher tiller survival, larger grain size, and shorter straw than Olympic in all years. In 1965 and 1966 its harvest index and the percentage of plant nitrogen in the grain responded more to higher soil nitrogen than that of Olympic.

scholarly journals HD-Tree: An Efficient High-Dimensional Virtual Index Structure Using a Half Decomposition Strategy

Algorithms ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 338
Author(s):  
Ting Huang ◽  
Zhengping Weng ◽  
Gang Liu ◽  
Zhenwen He
Keyword(s):  
Hash Table ◽  
Index Structure ◽  
High Dimensional ◽  
Sequential Search ◽  
Storage Space ◽  
Hash Tables ◽  
Time Performance ◽  
Indexing Method ◽  
Point Data ◽  
Better Than

To manage multidimensional point data more efficiently, this paper presents an improvement, called HD-tree, of a previous indexing method, called D-tree. Both structures combine quadtree-like partitioning (using integer shift operations without storing internal nodes, but only leaves) and hash tables (for searching for the nodes stored). However, the HD-tree follows a brand-new decomposition strategy, which is called half decomposition strategy. This improvement avoids the generation of nodes containing only a small amount of data and the sequential search of the hash table, so that it can save storage space while having faster I/O and better time performance when building the tree and querying data. The results demonstrate convincingly that the time and space performance of HD-tree is better than that of D-tree regardless of uniform or uneven data, which are less affected by data distribution.

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