Synthetic aperture radar (SAR) is theoretically based on uniform rectilinear motion. But in real situations, the flight cannot be kept in a uniform rectilinear motion due to many factors. Therefore, the motion compens...Synthetic aperture radar (SAR) is theoretically based on uniform rectilinear motion. But in real situations, the flight cannot be kept in a uniform rectilinear motion due to many factors. Therefore, the motion compensation is needed to achieve the high-resolution image. This paper proposes an improved motion information sensor (MIS)-based on global navigation statellite system (GNSS) and strapdown inertial navigation system (SINS) for SAR motion compensation. MIS can provide the long-term absolute accuracy, and the short-term high relative accuracy during SAR imaging. Many issues related to MIS, such as system design, error models and navigation algorithms, are stressed. Experimental results show that MIS can provide accurate navigation information (position, velocity and attitude) to meet the requirements of SAR motion compensation. Especially, MIS is suitable for the case: the accuracy of airplane master inertial navigation system is too low or not configured.展开更多
Cluster Synthetic Aperture Radar (SAR) system is composed of a group of spaceborne SAR systems. With its agility of combination, this system can work in several different modes. In this letter, the basic configuration...Cluster Synthetic Aperture Radar (SAR) system is composed of a group of spaceborne SAR systems. With its agility of combination, this system can work in several different modes. In this letter, the basic configuration and the working mode of the system are presented.The special performance of the system compared with the conventional SAR system is indicated.展开更多
Biomedical applications of porous calcium car- bonate （CaCO3） microspheres have been mainly restricted by their aqueous instability and low remineralization rate. To overcome these obstacles, a novel symmetry-breaki...Biomedical applications of porous calcium car- bonate （CaCO3） microspheres have been mainly restricted by their aqueous instability and low remineralization rate. To overcome these obstacles, a novel symmetry-breaking assembled porous calcite microsphere （PCMS） was con- structed in an ethanol/water mixed system using a two-step vapor-diffusion/aging crystallization strategy. In contrast to the conventional additive-induced crystallization method, the present strategy was performed under mild conditions and was free from any foreign additives, thus avoiding the potential contamination of the final product. Meanwhile, the prepared PCMSs were characterized by their highly uniform spherical morphology and large open pores, which are fa- vorable for large protein delivery. An antimicrobial study of immunoglobulin Y （IgY）-loaded PCMSs revealed excellent antimicrobial activity against Streptococcus mutans. More importantly, they showed surprisingly rapid transformation to bone minerals in physiological medium. Evaluation of the in vitro efficacy of PCMSs in dentinal tubule occlusion demonstrated their powerful potential to serve as a catalyst in the repair of dental hard tissue. Therefore, the developed PCMSs show great promise as multifunctional biomaterials for dental treatment applications.展开更多
文摘Synthetic aperture radar (SAR) is theoretically based on uniform rectilinear motion. But in real situations, the flight cannot be kept in a uniform rectilinear motion due to many factors. Therefore, the motion compensation is needed to achieve the high-resolution image. This paper proposes an improved motion information sensor (MIS)-based on global navigation statellite system (GNSS) and strapdown inertial navigation system (SINS) for SAR motion compensation. MIS can provide the long-term absolute accuracy, and the short-term high relative accuracy during SAR imaging. Many issues related to MIS, such as system design, error models and navigation algorithms, are stressed. Experimental results show that MIS can provide accurate navigation information (position, velocity and attitude) to meet the requirements of SAR motion compensation. Especially, MIS is suitable for the case: the accuracy of airplane master inertial navigation system is too low or not configured.
基金Supported by the university doctorate special research fund (No.20030614001)
文摘Cluster Synthetic Aperture Radar (SAR) system is composed of a group of spaceborne SAR systems. With its agility of combination, this system can work in several different modes. In this letter, the basic configuration and the working mode of the system are presented.The special performance of the system compared with the conventional SAR system is indicated.
基金supported by the National Natural Science Foundation ofChina (51402329 and 81500806)the Science Foundation for Youth Scholar of State Key Laboratory of High Performance Ceramics and Superfine Microstructures (SKL201404)Shanghai Excellent Academic Leaders Program (14XD1403800)
文摘Biomedical applications of porous calcium car- bonate （CaCO3） microspheres have been mainly restricted by their aqueous instability and low remineralization rate. To overcome these obstacles, a novel symmetry-breaking assembled porous calcite microsphere （PCMS） was con- structed in an ethanol/water mixed system using a two-step vapor-diffusion/aging crystallization strategy. In contrast to the conventional additive-induced crystallization method, the present strategy was performed under mild conditions and was free from any foreign additives, thus avoiding the potential contamination of the final product. Meanwhile, the prepared PCMSs were characterized by their highly uniform spherical morphology and large open pores, which are fa- vorable for large protein delivery. An antimicrobial study of immunoglobulin Y （IgY）-loaded PCMSs revealed excellent antimicrobial activity against Streptococcus mutans. More importantly, they showed surprisingly rapid transformation to bone minerals in physiological medium. Evaluation of the in vitro efficacy of PCMSs in dentinal tubule occlusion demonstrated their powerful potential to serve as a catalyst in the repair of dental hard tissue. Therefore, the developed PCMSs show great promise as multifunctional biomaterials for dental treatment applications.
