平方公里阵SKA(Square Kilometre Array)将是世界上最大的综合孔径射电望远镜,致力于回答宇宙起源等基本问题.目前SKA项目已进入建设准备阶段,包括中国在内的许多国家正在进行先导天线、相控阵馈源、超宽带单波束馈源等关键技术的试验研...平方公里阵SKA(Square Kilometre Array)将是世界上最大的综合孔径射电望远镜,致力于回答宇宙起源等基本问题.目前SKA项目已进入建设准备阶段,包括中国在内的许多国家正在进行先导天线、相控阵馈源、超宽带单波束馈源等关键技术的试验研究.其中,中国验证天线DVA-C(Dish Verification Antenna-China)是我国针对SKA中频反射面天线阵列提出的技术方案.文章详细介绍了DVA-C的微波光学与馈源的设计思路、方法和研究成果,以及预期达到的指标.由于DVA-C以轴向波束性能最优作为设计原则,对使用相控阵馈源的多波束观测造成了一定影响,故文中对此也进行了仿真和分析,并提出了应对的方案.展开更多
Fujian cuisine is a distinctive Chinese cuisine.Today,there are many faults and mistakes in the translation of the dish names,which leads to the failure and inconvenience of cross-cultural communication.The paper is a...Fujian cuisine is a distinctive Chinese cuisine.Today,there are many faults and mistakes in the translation of the dish names,which leads to the failure and inconvenience of cross-cultural communication.The paper is an attempt to probe into the appropriate translation of Fujian dish names by the employment of explicitation.展开更多
The technology of small point-focusing concentrator of solar energy has been developing rapidly in recent years owing to its compact structure and high collecting efficiency. This report presents important development...The technology of small point-focusing concentrator of solar energy has been developing rapidly in recent years owing to its compact structure and high collecting efficiency. This report presents important developments of small point-focusing concentrator in the past decade. This kind of solar concentrator refers to the parabolic dish concentrator, the point-focusing Fresnel lens, and the Scheffler reflector. Technological advances of these concentrators and the related performances have been presented. There are three main mirror fabrication technologies for dish concentrator, which are high polishing metal, silver-glass mirror and vacuum-membrane. Polymethyl methacrylate is widely used as material in Fresnel lens. Many scholars have proposed new lens shape to improve the uniformity of focusing. The Scheffler reflector has a characteristic of fixed focus, but its design parameters are not perfect so current research focuses on the theoretical calculation of the mirror. In addition, typical applications of the small point-focusing concentrator in photovoltaic system, solar thermal system, solar chemical system, and day-lighting system are summarized. Upon listing the important publications in open literature, a category of main applications of such kind of solar collector is provided based on the working characteristics of the system.展开更多
Two high concentrating solar systems have been established with dish concentrator and plane-mirrors array concentrator.In the paper,the thermal performance has been experimentally studied with jet water cooling device...Two high concentrating solar systems have been established with dish concentrator and plane-mirrors array concentrator.In the paper,the thermal performance has been experimentally studied with jet water cooling device and flat microchannel water-cooled device.The experimental results show that the maximum surface temperature difference of the dish concentrating system is greater than 20°C,while the plane-mirrors array system is lower than 4°C.It indicates that the plane-mirrors array concentrator has better uniformity.As the concentration ratio increases,the electrical efficiency of the concentrating photovoltaic system gradually decreases.When the concentration ratio is 200,the electrical efficiency of the photovoltaic system is 25%.The concentration ratio of 500 times or less is considered to be a suitable value,and then the electrical efficiency can still exceed 20%.It is found that the plane-mirrors array solar system is more suitable for the photovoltaic system than dish type system,which is only suitable for thermal power generation system.展开更多
Diffuse idiopathic skeletal hyperostosis(DISH) is a prevalent noninflammatory spondyloarthropathy characterized by ectopic mineral formation along the anterolateral aspect of the vertebral column, yet little is known ...Diffuse idiopathic skeletal hyperostosis(DISH) is a prevalent noninflammatory spondyloarthropathy characterized by ectopic mineral formation along the anterolateral aspect of the vertebral column, yet little is known about its underlying pathogenesis. Our objective was to evaluate the histopathological features and composition of ectopic mineral within spinal tissues affected by DISH in humans. Thoracic spine segments from six embalmed cadaveric donors(one female and five males;median age 82 years)meeting the radiographic diagnostic criteria for DISH were evaluated using radiological, histological, and physical analyses. Overall,the histological features of ectopic mineralization at individual motion segments were heterogeneous, including regions of heterotopic ossification and dystrophic calcification. Heterotopic ossifications were characterized by woven and lamellar bone,multifocal areas of metaplastic cartilage, and bony bridges along the anterior aspect of the intervertebral disc space. Dystrophic calcifications were characterized by an amorphous appearance, a high content of calcium and phosphorus, an X-ray diffraction pattern matching that of hydroxyapatite, and radiodensities exceeding that of cortical bone. Dystrophic calcifications were found within the anterior longitudinal ligament and annulus fibrosus in motion segments both meeting and not meeting the radiographic criteria for DISH. In summary, our findings indicate that in DISH, ectopic mineral forms along the anterior aspect of the spine by both heterotopic ossification and dystrophic calcification of fibrocartilaginous tissues. Although both types of ectopic mineralization are captured by current radiographic criteria for DISH, dystrophic calcification may reflect a distinct disease process or an early stage in the pathogenesis of DISH.展开更多
The three dimensional lead rubber dish spring bearing (3DB) is proposed in this paper. The 3DB is composed of lead rubber bearing (LRB) and dish spring bearing (DSB) with damper in series. The 3DB put forward in t...The three dimensional lead rubber dish spring bearing (3DB) is proposed in this paper. The 3DB is composed of lead rubber bearing (LRB) and dish spring bearing (DSB) with damper in series. The 3DB put forward in this paper is effective in the resolution of difficulties in strong vertical capacity and vertical damping of three dimensional isolation bearings. It effectively suppresses rocking motions as well. The analytical model and motion equations of multi dimensional seismic responses of 3D base isolated frame structures are established. Taking a five storey frame structure as an example, an extensive simulation analysis is carried out. The results show that the 3D base isolated structure with the proposed 3DB is effective in 3D isolation; it can reduce seismic responses by 50 % compared to a non isolated structure. Therefore, the 3D isolation problem in building can be solved easily and effectively with the 3DB proposed in this paper.展开更多
文摘平方公里阵SKA(Square Kilometre Array)将是世界上最大的综合孔径射电望远镜,致力于回答宇宙起源等基本问题.目前SKA项目已进入建设准备阶段,包括中国在内的许多国家正在进行先导天线、相控阵馈源、超宽带单波束馈源等关键技术的试验研究.其中,中国验证天线DVA-C(Dish Verification Antenna-China)是我国针对SKA中频反射面天线阵列提出的技术方案.文章详细介绍了DVA-C的微波光学与馈源的设计思路、方法和研究成果,以及预期达到的指标.由于DVA-C以轴向波束性能最优作为设计原则,对使用相控阵馈源的多波束观测造成了一定影响,故文中对此也进行了仿真和分析,并提出了应对的方案.
文摘Fujian cuisine is a distinctive Chinese cuisine.Today,there are many faults and mistakes in the translation of the dish names,which leads to the failure and inconvenience of cross-cultural communication.The paper is an attempt to probe into the appropriate translation of Fujian dish names by the employment of explicitation.
基金sponsored by the National Key Basic Research Program of China (No. 2015CB251303)
文摘The technology of small point-focusing concentrator of solar energy has been developing rapidly in recent years owing to its compact structure and high collecting efficiency. This report presents important developments of small point-focusing concentrator in the past decade. This kind of solar concentrator refers to the parabolic dish concentrator, the point-focusing Fresnel lens, and the Scheffler reflector. Technological advances of these concentrators and the related performances have been presented. There are three main mirror fabrication technologies for dish concentrator, which are high polishing metal, silver-glass mirror and vacuum-membrane. Polymethyl methacrylate is widely used as material in Fresnel lens. Many scholars have proposed new lens shape to improve the uniformity of focusing. The Scheffler reflector has a characteristic of fixed focus, but its design parameters are not perfect so current research focuses on the theoretical calculation of the mirror. In addition, typical applications of the small point-focusing concentrator in photovoltaic system, solar thermal system, solar chemical system, and day-lighting system are summarized. Upon listing the important publications in open literature, a category of main applications of such kind of solar collector is provided based on the working characteristics of the system.
基金supported by the Natural Science Foundation of Jiangsu Educational committee (No.18KJD480001)Innovation Practice Project of Yangzhong (No. YZGXYJS2018-KYCX-012)
文摘Two high concentrating solar systems have been established with dish concentrator and plane-mirrors array concentrator.In the paper,the thermal performance has been experimentally studied with jet water cooling device and flat microchannel water-cooled device.The experimental results show that the maximum surface temperature difference of the dish concentrating system is greater than 20°C,while the plane-mirrors array system is lower than 4°C.It indicates that the plane-mirrors array concentrator has better uniformity.As the concentration ratio increases,the electrical efficiency of the concentrating photovoltaic system gradually decreases.When the concentration ratio is 200,the electrical efficiency of the photovoltaic system is 25%.The concentration ratio of 500 times or less is considered to be a suitable value,and then the electrical efficiency can still exceed 20%.It is found that the plane-mirrors array solar system is more suitable for the photovoltaic system than dish type system,which is only suitable for thermal power generation system.
基金supported by the Canadian Institutes of Health Research (grant number 115068)。
文摘Diffuse idiopathic skeletal hyperostosis(DISH) is a prevalent noninflammatory spondyloarthropathy characterized by ectopic mineral formation along the anterolateral aspect of the vertebral column, yet little is known about its underlying pathogenesis. Our objective was to evaluate the histopathological features and composition of ectopic mineral within spinal tissues affected by DISH in humans. Thoracic spine segments from six embalmed cadaveric donors(one female and five males;median age 82 years)meeting the radiographic diagnostic criteria for DISH were evaluated using radiological, histological, and physical analyses. Overall,the histological features of ectopic mineralization at individual motion segments were heterogeneous, including regions of heterotopic ossification and dystrophic calcification. Heterotopic ossifications were characterized by woven and lamellar bone,multifocal areas of metaplastic cartilage, and bony bridges along the anterior aspect of the intervertebral disc space. Dystrophic calcifications were characterized by an amorphous appearance, a high content of calcium and phosphorus, an X-ray diffraction pattern matching that of hydroxyapatite, and radiodensities exceeding that of cortical bone. Dystrophic calcifications were found within the anterior longitudinal ligament and annulus fibrosus in motion segments both meeting and not meeting the radiographic criteria for DISH. In summary, our findings indicate that in DISH, ectopic mineral forms along the anterior aspect of the spine by both heterotopic ossification and dystrophic calcification of fibrocartilaginous tissues. Although both types of ectopic mineralization are captured by current radiographic criteria for DISH, dystrophic calcification may reflect a distinct disease process or an early stage in the pathogenesis of DISH.
文摘The three dimensional lead rubber dish spring bearing (3DB) is proposed in this paper. The 3DB is composed of lead rubber bearing (LRB) and dish spring bearing (DSB) with damper in series. The 3DB put forward in this paper is effective in the resolution of difficulties in strong vertical capacity and vertical damping of three dimensional isolation bearings. It effectively suppresses rocking motions as well. The analytical model and motion equations of multi dimensional seismic responses of 3D base isolated frame structures are established. Taking a five storey frame structure as an example, an extensive simulation analysis is carried out. The results show that the 3D base isolated structure with the proposed 3DB is effective in 3D isolation; it can reduce seismic responses by 50 % compared to a non isolated structure. Therefore, the 3D isolation problem in building can be solved easily and effectively with the 3DB proposed in this paper.
