Quadrature Spatial Modulation (QSM) is a high spectral efficiency Multiple-Input Multiple Output (MIMO) technique used to improve the spectral efficiency of wireless communication systems. The main concept of QSM is t...Quadrature Spatial Modulation (QSM) is a high spectral efficiency Multiple-Input Multiple Output (MIMO) technique used to improve the spectral efficiency of wireless communication systems. The main concept of QSM is to extend the spatial constellation of the conventional Spatial Modulation (SM) in both the in-phase and quadrature components of the data symbol. In this paper, because QSM-based on Interleaxdng Division Multiplexing (IDM) has not been introduced in the literature as a multiple antenna system, we introduced a novel scheme, called QSM system based on Interleaving Division Multiplexing (QSM-IDM). The antenna sets are also applied to a spreader, before being used to assign an antenna number for information transmission. Analysis and simulations for a flat fading channel show that the proposed QSM-IDM method significantly outperforms the original QSM system with the same data rate, while maintaining a relatively acceptable complexity. The obtained simulation results show that the conducted analysis yields significant improvements for the accuracy of the proposed scheme, with satisfactory complexity.展开更多
Trees are able to adapt to changing environmental conditions through modifications in their crown morphology and branch architecture.In light-limited environments,tree structures are mainly optimised to increase light...Trees are able to adapt to changing environmental conditions through modifications in their crown morphology and branch architecture.In light-limited environments,tree structures are mainly optimised to increase light interception.This might have side effects on other properties such as the hydraulic system that determines water conduction and tree reactions to drought events.Given the increasing exposure of forest ecosystems to drought stress it is thus crucial to investigate possible correlations between the crown morphology and branch architecture and drought responses.Our study aimed to compare different crown archetypes and branch characteristics of European beech(Fagus sylvatica L.)in their reaction to drought,which was assessed by measuring tree-ring widths of increment cores sampled at breast height.Using Terrestrial Laser Scanning and Quantitative Structure Models,we explored various crown morphological and branch architectural characteristics of 67 beech trees and identified three species-specific crown archetypes.The crown archetypes and branch variables were contrasted with growth responses using linear mixed models.While productivity levels differed,the negative impact of drought stress on radial growth was consistent across all crown archetypes.Nevertheless,certain branch architectural variables were important predictors for radial growth in drought situations.Specifically,long water conduction paths and many branching nodes along those paths were positively influencing growth.Our results indicate that trees showing these characteristics might have a competitive edge regarding drought-affected radial growth compared to others.They could be promoted through thinning measures,which would allow improving the adaption of existing beech forests in situ to climate change and drought stress.展开更多
定量磁化率成像(quantitative susceptibility mapping,QSM)技术大多采用多回波梯度回波序列采集相位数据,经加权最小二乘法(weighted linear least-square,WLS)拟合得到局部磁场分布.对于组织磁化率分布不均匀的区域,尤其是颅底部位,常...定量磁化率成像(quantitative susceptibility mapping,QSM)技术大多采用多回波梯度回波序列采集相位数据,经加权最小二乘法(weighted linear least-square,WLS)拟合得到局部磁场分布.对于组织磁化率分布不均匀的区域,尤其是颅底部位,常规WLS算法拟合得到的局部磁场误差较大,导致相应部位磁化率分布图信噪比较低.针对常规WLS算法的这一不足,该文提出了一种截断WLS算法.对两种算法拟合得到的磁化率分布图对比研究发现,截断WLS算法可有效提高颅底部位定量磁化率分布图的图像质量,使其噪声明显下降.展开更多
文摘Quadrature Spatial Modulation (QSM) is a high spectral efficiency Multiple-Input Multiple Output (MIMO) technique used to improve the spectral efficiency of wireless communication systems. The main concept of QSM is to extend the spatial constellation of the conventional Spatial Modulation (SM) in both the in-phase and quadrature components of the data symbol. In this paper, because QSM-based on Interleaxdng Division Multiplexing (IDM) has not been introduced in the literature as a multiple antenna system, we introduced a novel scheme, called QSM system based on Interleaving Division Multiplexing (QSM-IDM). The antenna sets are also applied to a spreader, before being used to assign an antenna number for information transmission. Analysis and simulations for a flat fading channel show that the proposed QSM-IDM method significantly outperforms the original QSM system with the same data rate, while maintaining a relatively acceptable complexity. The obtained simulation results show that the conducted analysis yields significant improvements for the accuracy of the proposed scheme, with satisfactory complexity.
基金funding received from the Project“Hochaufgeloste Quanti fizierung des N ahrstoffentzuges bei verschiedenen Ernteszenarien der Buche”through the GFH Freiburg,which assisted with laser scanningsupported by the German Federal Ministry of Food and Agriculture and the Federal Ministry for the Environment,Nature Conservation,Nuclear Safety and Consumer Protection(grant:2219WK60C4)。
文摘Trees are able to adapt to changing environmental conditions through modifications in their crown morphology and branch architecture.In light-limited environments,tree structures are mainly optimised to increase light interception.This might have side effects on other properties such as the hydraulic system that determines water conduction and tree reactions to drought events.Given the increasing exposure of forest ecosystems to drought stress it is thus crucial to investigate possible correlations between the crown morphology and branch architecture and drought responses.Our study aimed to compare different crown archetypes and branch characteristics of European beech(Fagus sylvatica L.)in their reaction to drought,which was assessed by measuring tree-ring widths of increment cores sampled at breast height.Using Terrestrial Laser Scanning and Quantitative Structure Models,we explored various crown morphological and branch architectural characteristics of 67 beech trees and identified three species-specific crown archetypes.The crown archetypes and branch variables were contrasted with growth responses using linear mixed models.While productivity levels differed,the negative impact of drought stress on radial growth was consistent across all crown archetypes.Nevertheless,certain branch architectural variables were important predictors for radial growth in drought situations.Specifically,long water conduction paths and many branching nodes along those paths were positively influencing growth.Our results indicate that trees showing these characteristics might have a competitive edge regarding drought-affected radial growth compared to others.They could be promoted through thinning measures,which would allow improving the adaption of existing beech forests in situ to climate change and drought stress.
文摘定量磁化率成像(quantitative susceptibility mapping,QSM)技术大多采用多回波梯度回波序列采集相位数据,经加权最小二乘法(weighted linear least-square,WLS)拟合得到局部磁场分布.对于组织磁化率分布不均匀的区域,尤其是颅底部位,常规WLS算法拟合得到的局部磁场误差较大,导致相应部位磁化率分布图信噪比较低.针对常规WLS算法的这一不足,该文提出了一种截断WLS算法.对两种算法拟合得到的磁化率分布图对比研究发现,截断WLS算法可有效提高颅底部位定量磁化率分布图的图像质量,使其噪声明显下降.
