Lateral dispersion significantly directs the assessment of rockfall hazard and design of countermeasures. In the present study, the dependence of lateral dispersion on different controlling factors has been systematic...Lateral dispersion significantly directs the assessment of rockfall hazard and design of countermeasures. In the present study, the dependence of lateral dispersion on different controlling factors has been systematically evaluated by performing laboratory tests using three different rock block types, namely circular block, and two types of elliptical block. The three types of rock block are released onto an inclined surface with the identical initial status. Parallel, anti-parallel, and oblique impact tests set at slope angles of 22.5° and 45°are conducted to study the block-slope interaction of rockfall. Lateral dispersion of rockfall is less influenced by the block shape for the oblique impact, while the post-impact behaviors are greatly affected by the block shape. The key factors influencing the deviation of the post-impact trajectory direction are the slope angle (θ) and direction difference (Δφ). An empirical model is then developed to characterize the deviation distribution of lateral dispersion by 5th and 95th percentile values with the inclusion of the two key factors. Linear function can be used to describe the 5th percentile boundary, while hyperbolic function is good for the 95th percentile boundary, which need to be validated by field tests in the subsequent research.展开更多
Lateral solid mixing was investigated experimentally in the dense zone of a 900mm×100mm×5.2m rectangular circulating fluidized bed riser.Using heated tracer injection,the lateral solid dispersion was determ...Lateral solid mixing was investigated experimentally in the dense zone of a 900mm×100mm×5.2m rectangular circulating fluidized bed riser.Using heated tracer injection,the lateral solid dispersion was determined by measuring the temperature response at different lateral positions. Furthermore, a one-dimensional dispersion model,which describes the solid mixing in the dense zone,is presented.The experimental results were used to determine the lateral particle dispersion coefficient under various operating conditions. A correlation of dispersion coefficient with bed height, gas velocity,and particle size is also proposed.展开更多
随着神经退行性疾病的发病率不断上升,迫切需要一种生物标志物能够在重度神经元丢失出现之前检测到疾病的病理变化,以促进疾病的早期干预。神经突方向离散度和密度成像(neurite orientation dispersion and density imaging,NODDI)是一...随着神经退行性疾病的发病率不断上升,迫切需要一种生物标志物能够在重度神经元丢失出现之前检测到疾病的病理变化,以促进疾病的早期干预。神经突方向离散度和密度成像(neurite orientation dispersion and density imaging,NODDI)是一种新型的扩散MRI多室生物物理模型,能够量化神经突的密度与纤维分散程度,特异性地反映脑组织微观结构的改变。目前,该技术已用于多种神经退行性疾病的研究。本文就NODDI的技术原理及其在神经退行性疾病中的应用进行综述,以期为今后的研究提供影像学参考。展开更多
基金support from the Natural Science Foundation of China(Grant Nos.42177165 and 41672302)the Opening fund of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Chengdu University of Technology)(Grant No.SKLGP2018K018).
文摘Lateral dispersion significantly directs the assessment of rockfall hazard and design of countermeasures. In the present study, the dependence of lateral dispersion on different controlling factors has been systematically evaluated by performing laboratory tests using three different rock block types, namely circular block, and two types of elliptical block. The three types of rock block are released onto an inclined surface with the identical initial status. Parallel, anti-parallel, and oblique impact tests set at slope angles of 22.5° and 45°are conducted to study the block-slope interaction of rockfall. Lateral dispersion of rockfall is less influenced by the block shape for the oblique impact, while the post-impact behaviors are greatly affected by the block shape. The key factors influencing the deviation of the post-impact trajectory direction are the slope angle (θ) and direction difference (Δφ). An empirical model is then developed to characterize the deviation distribution of lateral dispersion by 5th and 95th percentile values with the inclusion of the two key factors. Linear function can be used to describe the 5th percentile boundary, while hyperbolic function is good for the 95th percentile boundary, which need to be validated by field tests in the subsequent research.
文摘Lateral solid mixing was investigated experimentally in the dense zone of a 900mm×100mm×5.2m rectangular circulating fluidized bed riser.Using heated tracer injection,the lateral solid dispersion was determined by measuring the temperature response at different lateral positions. Furthermore, a one-dimensional dispersion model,which describes the solid mixing in the dense zone,is presented.The experimental results were used to determine the lateral particle dispersion coefficient under various operating conditions. A correlation of dispersion coefficient with bed height, gas velocity,and particle size is also proposed.
文摘随着神经退行性疾病的发病率不断上升,迫切需要一种生物标志物能够在重度神经元丢失出现之前检测到疾病的病理变化,以促进疾病的早期干预。神经突方向离散度和密度成像(neurite orientation dispersion and density imaging,NODDI)是一种新型的扩散MRI多室生物物理模型,能够量化神经突的密度与纤维分散程度,特异性地反映脑组织微观结构的改变。目前,该技术已用于多种神经退行性疾病的研究。本文就NODDI的技术原理及其在神经退行性疾病中的应用进行综述,以期为今后的研究提供影像学参考。
