遮挡效应是多天线复杂系统设计一个重要考虑因素。国家重大科技基础设施项目子午工程二期建设完成后,明安图台站各类天线总数将达到373套。受限于测试场地、模型复杂度和计算量,特别是对电大尺寸障碍物的遮挡效应通常很难实测和预测。...遮挡效应是多天线复杂系统设计一个重要考虑因素。国家重大科技基础设施项目子午工程二期建设完成后,明安图台站各类天线总数将达到373套。受限于测试场地、模型复杂度和计算量,特别是对电大尺寸障碍物的遮挡效应通常很难实测和预测。明安图台站太阳射电望远镜(Mingantu Solar Radio Telescope,MST)在2017~2020年S,C和X频段的观测数据显示了以20 m天线和远方丘陵为障碍物的遮挡效应,并可以分为天线、大气和丘陵3个不同特性区域。基于ITU-R P.526-15建议书单刃峰绕射损耗预测方法,进行20 m天线反射面仿真建模和近似计算。观测和仿真结果显示,绕射损耗随频率变化趋势基本一致,遮挡效应与波长、障碍物特性及其相对源和接收天线的距离和角度、接收设备的天线波束和动态范围等有关。展开更多
Silk derived from the silkworm Bombyx mori is among the most important fibrous protein biomaterials due to large-scale production from natural sources, excellent biocompatibility, unique mechanical properties and cont...Silk derived from the silkworm Bombyx mori is among the most important fibrous protein biomaterials due to large-scale production from natural sources, excellent biocompatibility, unique mechanical properties and controllable degradation. Silk fibroin can be processed into a variety of formats to match different applications, such as tissue engineering, drug delivery or as the passive substrate of a bio-device. Advances in fabrication technologies provide new possibilities for the combination of silk fibroin with other nanomaterials to functionalize silk fibroin for specialized purposes, including sensing, cell visualization,resistance to ultraviolet light and provision of antibacterial properties. As the requirement for wearable and intelligent devices has become increasingly important over recent years, silk fibroin has been utilized as the active element in electronic and optical instruments. This review summarizes these recent advances in the innovative applications of silk fibroin.展开更多
Two different chemical methods, TEMPO-oxidation and nitro-oxidation, were used to extract carboxyl cellulose nanofibers(CNFs) from non-wood biomass sources(i.e., jute, soft and hard spinifex grasses). The combined TEM...Two different chemical methods, TEMPO-oxidation and nitro-oxidation, were used to extract carboxyl cellulose nanofibers(CNFs) from non-wood biomass sources(i.e., jute, soft and hard spinifex grasses). The combined TEMPO-oxidation and homogenization approach was very efficient to produce CNFs from the cellulose component of biomass;however, the nitrooxidation method was also found to be effective to extract CNFs directly from raw biomass even without mechanical treatment.The effect of these two methods on the resulting cross-section dimensions of CNFs was investigated by solution small-angle Xray scattering(SAXS), transmission electron microscopy(TEM) and atomic force microscopy(AFM). The UV-Vis spectroscopic data from 0.1 wt% TEMPO-oxidized nanofiber(TOCNF) and nitro-oxidized nanofiber(NOCNF) suspensions showed that TOCNF had the highest transparency(> 95%) because of better dispersion, resulted from the highest carboxylate content(1.2 mmol/g). The consistent scattering and microscopic results indicated that TOCNFs from jute and spinifex grasses possessed rectangular cross-sections, while NOCNFs exhibited near square cross-sections. This study revealed that different oxidation methods can result in different degrees of biomass exfoliation and different CNF morphology.展开更多
文摘遮挡效应是多天线复杂系统设计一个重要考虑因素。国家重大科技基础设施项目子午工程二期建设完成后,明安图台站各类天线总数将达到373套。受限于测试场地、模型复杂度和计算量,特别是对电大尺寸障碍物的遮挡效应通常很难实测和预测。明安图台站太阳射电望远镜(Mingantu Solar Radio Telescope,MST)在2017~2020年S,C和X频段的观测数据显示了以20 m天线和远方丘陵为障碍物的遮挡效应,并可以分为天线、大气和丘陵3个不同特性区域。基于ITU-R P.526-15建议书单刃峰绕射损耗预测方法,进行20 m天线反射面仿真建模和近似计算。观测和仿真结果显示,绕射损耗随频率变化趋势基本一致,遮挡效应与波长、障碍物特性及其相对源和接收天线的距离和角度、接收设备的天线波束和动态范围等有关。
基金supported by the National Key Research and Development Program of China(Grant Nos.2016YFA0201702,2018YFC1105800,2018YFC1106002)the National Natural Science Foundation of China(Grant No.21674018)+3 种基金the International Joint Laboratory for Advanced Fiber and Low-dimension Materials(Grant No.18520750400)the “Shuguang Program” supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission(Grant No.15SG30)the Youth Foundation of Donghua University(Grant No.106-07-0053028)the Fundamental Research Funds for the Central Universities
文摘Silk derived from the silkworm Bombyx mori is among the most important fibrous protein biomaterials due to large-scale production from natural sources, excellent biocompatibility, unique mechanical properties and controllable degradation. Silk fibroin can be processed into a variety of formats to match different applications, such as tissue engineering, drug delivery or as the passive substrate of a bio-device. Advances in fabrication technologies provide new possibilities for the combination of silk fibroin with other nanomaterials to functionalize silk fibroin for specialized purposes, including sensing, cell visualization,resistance to ultraviolet light and provision of antibacterial properties. As the requirement for wearable and intelligent devices has become increasingly important over recent years, silk fibroin has been utilized as the active element in electronic and optical instruments. This review summarizes these recent advances in the innovative applications of silk fibroin.
基金supported by the Polymer Program from Division of Materials Science of the National Science Foundation of USA(Grant No.DMR-1808690)supported by an NIH-NIGMS(Grant No.P41GM111244)
文摘Two different chemical methods, TEMPO-oxidation and nitro-oxidation, were used to extract carboxyl cellulose nanofibers(CNFs) from non-wood biomass sources(i.e., jute, soft and hard spinifex grasses). The combined TEMPO-oxidation and homogenization approach was very efficient to produce CNFs from the cellulose component of biomass;however, the nitrooxidation method was also found to be effective to extract CNFs directly from raw biomass even without mechanical treatment.The effect of these two methods on the resulting cross-section dimensions of CNFs was investigated by solution small-angle Xray scattering(SAXS), transmission electron microscopy(TEM) and atomic force microscopy(AFM). The UV-Vis spectroscopic data from 0.1 wt% TEMPO-oxidized nanofiber(TOCNF) and nitro-oxidized nanofiber(NOCNF) suspensions showed that TOCNF had the highest transparency(> 95%) because of better dispersion, resulted from the highest carboxylate content(1.2 mmol/g). The consistent scattering and microscopic results indicated that TOCNFs from jute and spinifex grasses possessed rectangular cross-sections, while NOCNFs exhibited near square cross-sections. This study revealed that different oxidation methods can result in different degrees of biomass exfoliation and different CNF morphology.
