Multi-seasonal evaluation of hybrid poplar (P. Deltoides) plantations using Worldview-3 imagery and State-Of-The-Art ensemble learning algorithms

Forest resources are the primary components of the ecosystem environment. Poplars (Populus sp.), a member of the fast-growing trees, are one of the most productive forest tree species for industrial production thanks to their desirable traits comprising rapid growth, hybridization ability, and ease of propagation. Determining poplar cultivated areas and mapping their geographical distributions is critical for planners and decision-makers to increase the ecological and economic benefits of poplar trees. Due to the biodiversity of each geographical region and seasonal vegetation variations, classification based on remotely sensed imagery is essential for cropland monitoring. The main goal of this study is to evaluate the potential of high-resolution multi-temporal (growing season and end of the growing season) Worldview-3 imagery in mapping poplar plantations in the Akyaz? district of Sakarya, Turkey. For this purpose, pixel- and object-based image analysis with up-to-date ensemble learning algorithms, namely random forest (RF), categorical boosting (CB), and extreme gradient boosting tree (XGB), were employed for mapping poplar fields. Results indicated that the object-based classification approach provided statistically significant improvements in map-level (about 4%) and class-level accuracy (e.g., approximately 7% and %2 for poplar and young poplar classes, respectively) than pixel-based classification. While the CB performed superior classification performance for the object-based approach (92.56%), the highest classification performance was obtained with the XGB algorithm for the pixel-based approach (90.42%) for the end of the growing season data. McNemar’s statistical test also confirmed that the performances of CB and XGB algorithms were statistically similar in pixel-based classification. Finally, analysis of multi-season images revealed that sensitivity of the vegetation phenology and seasonal effects considerably affect the separability of poplar tree species.     

Enhancement on parallel unstructured overset grid method for complex aerospace engineering applications

In the present study, an efficient overset grid method by means of parallel implicit hole-cutting is proposed for the sake of simulating unsteady flows in aerospace engineering involving multiple bodies in relative movement. In view of the degraded computational efficiency and robustness for conventional overset grid assembly, several innovative techniques are developed within the overset grid assembly process, viz., a bookkeeping alternative digital tree method to speed up the donor-cell search...     

基于 PDPC-EMV模型的装备研制方案优化设计

将全面质量管理的过程决策程序图法(PDPC)与决策分析技术的期望值法(EMV)有机结合,构建了PDPC-EMV理论模型,并将该模型引入到武器装备研制方案的设计环节中,用风险评估的思维解决全面质量管理的问题,为武器装备研制方案的设计工作开辟了一种先期质量控制思路。     

Calculating the simultaneous effect of ion dynamics and oscillating electric fields on Stark profiles

We calculate hydrogen line shapes resulting from the simultaneous Stark effect of the plasma microfield and an oscillating electric field. Like laboratory plasmas, many kinds of space plasmas are affected by oscillating electric fields with a magnitude similar to that of the microfield. Here we focus on conditions where we expect that the effect of ion dynamics and oscillating electric are both significant. The combined effect of their dynamics on the quantum emitter is retained by a computer simulation coupled to a numerical integration of the Schrödinger equation. Our calculations are applied for conditions and transitions where significant changes in the line shape allow for a diagnostic of the plasma and oscillating field.