A novel biased proportional navigation guidance （BPNG） law is proposed for the close approach phase, which aims to make the spacecraft rendezvous with the target in specific relative range and direction. Firstly, in...A novel biased proportional navigation guidance （BPNG） law is proposed for the close approach phase, which aims to make the spacecraft rendezvous with the target in specific relative range and direction. Firstly, in order to describe the special guidance requirements, the concept of zero effort miss vector is proposed and the dangerous area where there exists collision risk for safety consideration is defined. Secondly, the BPNG, which decouples the range control and direc- tion control, is designed in the line-of-sight （LOS） rotation coordinate system. The theoretical anal- ysis proves that BPNG meets guidance requirements quite well. Thirdly, for the consideration of fuel consumption, the optimal biased proportional navigation guidance （OBPNG） law is derived by solving the Schwartz inequality. Finally, simulation results show that BPNG is effective for the close approach with the ability of evading the dangerous area and OBPNG consumes less fuel compared with BPNG.展开更多
Endoscopic resection has been an optimal treatment for selected patients with early gastric cancer(EGC) based on advances in endoscopic instruments and techniques. As endoscopic submucosal dissection(ESD) has been wid...Endoscopic resection has been an optimal treatment for selected patients with early gastric cancer(EGC) based on advances in endoscopic instruments and techniques. As endoscopic submucosal dissection(ESD) has been widely used for treatment of EGC along with expanding ESD indication, concerns have been asked to achieve curative resection for EGC while guaranteeing precise prediction of lymph node metastasis(LNM). Recently, new techniques including ESD or endoscopic full-thickness resection combined with sentinel node navigation enable minimal tumor resection and a laparoscopic lymphadenectomy in cases of EGC with high risk of LNM. This review covers the development and challenges of endoscopic treatment for EGC. Moreover, a new microscopic imaging and endoscopic techniques for precise endoscopic diagnosis and minimally invasive treatment of EGC are introduced.展开更多
基金co-supported by the National Natural Science Foundation of China(No.11372345)the National Basic Research Program of China(No.2013CB733100)
文摘A novel biased proportional navigation guidance （BPNG） law is proposed for the close approach phase, which aims to make the spacecraft rendezvous with the target in specific relative range and direction. Firstly, in order to describe the special guidance requirements, the concept of zero effort miss vector is proposed and the dangerous area where there exists collision risk for safety consideration is defined. Secondly, the BPNG, which decouples the range control and direc- tion control, is designed in the line-of-sight （LOS） rotation coordinate system. The theoretical anal- ysis proves that BPNG meets guidance requirements quite well. Thirdly, for the consideration of fuel consumption, the optimal biased proportional navigation guidance （OBPNG） law is derived by solving the Schwartz inequality. Finally, simulation results show that BPNG is effective for the close approach with the ability of evading the dangerous area and OBPNG consumes less fuel compared with BPNG.
文摘Endoscopic resection has been an optimal treatment for selected patients with early gastric cancer(EGC) based on advances in endoscopic instruments and techniques. As endoscopic submucosal dissection(ESD) has been widely used for treatment of EGC along with expanding ESD indication, concerns have been asked to achieve curative resection for EGC while guaranteeing precise prediction of lymph node metastasis(LNM). Recently, new techniques including ESD or endoscopic full-thickness resection combined with sentinel node navigation enable minimal tumor resection and a laparoscopic lymphadenectomy in cases of EGC with high risk of LNM. This review covers the development and challenges of endoscopic treatment for EGC. Moreover, a new microscopic imaging and endoscopic techniques for precise endoscopic diagnosis and minimally invasive treatment of EGC are introduced.
