Aiming at the problem of relative navigation for non-cooperative rendezvous of spacecraft,this paper proposes a new angles-only navigation architecture using non-linear dynamics method. This method does not solve the ...Aiming at the problem of relative navigation for non-cooperative rendezvous of spacecraft,this paper proposes a new angles-only navigation architecture using non-linear dynamics method. This method does not solve the problem of poor observability of angles-only navigation through orbital or attitude maneuvering,but improves the observability of angles-only navigation through capturing the non-linearity of the system in the evolution of relative motion. First,three relative dynamics models and their corresponding line-of-sight(LoS)measurement equations are introduced,including the rectilinear state relative dynamics model,the curvilinear state relative dynamics model,and the relative orbital elements(ROE)state relative dynamics model. Then,an observability analysis theory based on the Gramian matrix is introduced to determine which relative dynamics model could maximize the observability of angles-only navigation. Next,an adaptive extended Kalman filtering scheme is proposed to solve the problem that the angles-only navigation filter using the non-linear dynamics method is sensitive to measurement noises. Finally,the performances of the proposed angles-only navigation architecture are tested by means of numerical simulations,which demonstrates that the angles-only navigation filtering scheme without orbital or attitude maneuvering is completely feasible through improving the modeling of the relative dynamics and LoS measurement equations.展开更多
Malaria is one of the leading causes of consultation in African pediatric hospitals. In Gabon, malaria transmission is perennial. Plasmodium falciparum, responsible for the most severe form of the disease, represents ...Malaria is one of the leading causes of consultation in African pediatric hospitals. In Gabon, malaria transmission is perennial. Plasmodium falciparum, responsible for the most severe form of the disease, represents more than 95% of all species. In P. falciparum infection, the hyperparasitemia accounts among the main criteria of disease severity. However, in many endemic countries, a significant decrease of malaria burden accompanying with the diminution of parasite load in infected individuals has been demonstrated. The objective of the study was to analyze the occurrence of febrile syndrome in childhood and investigate whether the acute febrile illness could be associated with P. falciparum submicroscopic infection. A cross-sectional study was carried out during January to March 2013 in Franceville. A total of 203 acute febrile children were enrolled. A clinical examination and biomedical analysis including parasitological diagnosis by microscope were carried out in all the patients and PCR on microscope negative ones. Of 203 children recruited for febrile syndrome, 111 have been diagnosed positive for P. falciparum infection, 73 （35.9%） by microscope （ME） and 38 （18.71%） by PCR （submicroscopic infection = SM1） with an overall prevalence of 54.68%. Of the 11 1 P. falciparum infected individuals and according to the WHO criteria, 35 （31.53%） children showed a clinical picture of severe malaria against 76 （68.47%） others classified as uncomplicated malaria. The overall prevalence rates were therefore estimated as 17.24 （35/203） for severe cases and 37.43% （76/203） for uncomplicated ones. Clinically, these severe malaria cases （27 ME＋ and 8 PCR＋） were mainly composed of 85.71% of anaemic patients （30/35）, 71.14% of prostrated individuals （25/35） and 57.14% of children with clinical icterus （20/35）. However, only two cases of severe anaemia were observed, the remaining others cases were moderate （10） and mild anaemia （18）. More interestingly, eight submicroscopic infected patients （22.85%） were found with neurological manifestations （prostration） and all were experiencing thrombocytopenia. Lastly, 1 hyperparasitemia, 6 hypoglycemia and 2 respiratory distresses were also observed among these severe malaria cases. P. falciparum submicroscopic infection may lead to severe malaria in perennial transmission area.展开更多
WORI is the Production-Oriented Approach to reading in the TEFL context of China. It is intended to enhance English learners＇ proficiency in writing and reading. By asking questions to draw learners＇ attention to th...WORI is the Production-Oriented Approach to reading in the TEFL context of China. It is intended to enhance English learners＇ proficiency in writing and reading. By asking questions to draw learners＇ attention to the professional writers＇ choices concerning organization, development, style, and diction, teachers explicitly guide learners to observe, analyze, study, apperceive, so as to learn about their writing thinking and strategies. By designing a variety of reading-to-write tasks, teachers endeavour to activate learners＇ writing thinking developed in writing-oriented reading activities to have such writing thinking fixed in mind and internalized. The WORI also fosters English learners＇ autonomy of sustaining development in reading, writing, as well as their English learning.展开更多
In this work,the microstructure and optical properties of the Mo/Si multilayers mirror for the space extreme-ultraviolet solar telescope before and after 100 keV proton irradiation have been investigated.EUV/soft X-ra...In this work,the microstructure and optical properties of the Mo/Si multilayers mirror for the space extreme-ultraviolet solar telescope before and after 100 keV proton irradiation have been investigated.EUV/soft X-ray reflectometer(EXRR) results showed that,after proton irradiation,the reflectivity of the Mo/Si multilayer decreased from 12.20% to 8.34% and the center wavelength revealed red shift of 0.38 nm,as compared with those before proton irradiation.High-resolution transmission electron microscopy(HRTEM) observations revealed the presence of MoSi 2,Mo 3 Si and Mo 5 Si 3 in Mo-on-Si interlayers before irradiation.The preferred orientation such as MoSi 2 with(101) texture and Mo 5 Si 3 with(310) texture was formed in Mo-on-Si interlayers after proton irradiation,which led to the increase of thickness in the interlayers.It is suggested that the changes of microstructures in Mo/Si multilayers under proton irradiation could cause optical properties degradation.展开更多
The incidence and mortality of cancer have been increasing alarmingly in China and worldwide.Unlike other chronic diseases such as metabolic,cardiovascular,and neuropathies,most cancers,especially metastatic ones,are ...The incidence and mortality of cancer have been increasing alarmingly in China and worldwide.Unlike other chronic diseases such as metabolic,cardiovascular,and neuropathies,most cancers,especially metastatic ones,are still essentially uncontrollable in spite of significant progresses such as early diagnosis and immunotherapies.展开更多
基金supported by the China Aerospace Science and Technology Corporation Eighth Research Institute Industry-University-Research Cooperation Fund(No.SAST 2020-019)。
文摘Aiming at the problem of relative navigation for non-cooperative rendezvous of spacecraft,this paper proposes a new angles-only navigation architecture using non-linear dynamics method. This method does not solve the problem of poor observability of angles-only navigation through orbital or attitude maneuvering,but improves the observability of angles-only navigation through capturing the non-linearity of the system in the evolution of relative motion. First,three relative dynamics models and their corresponding line-of-sight(LoS)measurement equations are introduced,including the rectilinear state relative dynamics model,the curvilinear state relative dynamics model,and the relative orbital elements(ROE)state relative dynamics model. Then,an observability analysis theory based on the Gramian matrix is introduced to determine which relative dynamics model could maximize the observability of angles-only navigation. Next,an adaptive extended Kalman filtering scheme is proposed to solve the problem that the angles-only navigation filter using the non-linear dynamics method is sensitive to measurement noises. Finally,the performances of the proposed angles-only navigation architecture are tested by means of numerical simulations,which demonstrates that the angles-only navigation filtering scheme without orbital or attitude maneuvering is completely feasible through improving the modeling of the relative dynamics and LoS measurement equations.
文摘Malaria is one of the leading causes of consultation in African pediatric hospitals. In Gabon, malaria transmission is perennial. Plasmodium falciparum, responsible for the most severe form of the disease, represents more than 95% of all species. In P. falciparum infection, the hyperparasitemia accounts among the main criteria of disease severity. However, in many endemic countries, a significant decrease of malaria burden accompanying with the diminution of parasite load in infected individuals has been demonstrated. The objective of the study was to analyze the occurrence of febrile syndrome in childhood and investigate whether the acute febrile illness could be associated with P. falciparum submicroscopic infection. A cross-sectional study was carried out during January to March 2013 in Franceville. A total of 203 acute febrile children were enrolled. A clinical examination and biomedical analysis including parasitological diagnosis by microscope were carried out in all the patients and PCR on microscope negative ones. Of 203 children recruited for febrile syndrome, 111 have been diagnosed positive for P. falciparum infection, 73 （35.9%） by microscope （ME） and 38 （18.71%） by PCR （submicroscopic infection = SM1） with an overall prevalence of 54.68%. Of the 11 1 P. falciparum infected individuals and according to the WHO criteria, 35 （31.53%） children showed a clinical picture of severe malaria against 76 （68.47%） others classified as uncomplicated malaria. The overall prevalence rates were therefore estimated as 17.24 （35/203） for severe cases and 37.43% （76/203） for uncomplicated ones. Clinically, these severe malaria cases （27 ME＋ and 8 PCR＋） were mainly composed of 85.71% of anaemic patients （30/35）, 71.14% of prostrated individuals （25/35） and 57.14% of children with clinical icterus （20/35）. However, only two cases of severe anaemia were observed, the remaining others cases were moderate （10） and mild anaemia （18）. More interestingly, eight submicroscopic infected patients （22.85%） were found with neurological manifestations （prostration） and all were experiencing thrombocytopenia. Lastly, 1 hyperparasitemia, 6 hypoglycemia and 2 respiratory distresses were also observed among these severe malaria cases. P. falciparum submicroscopic infection may lead to severe malaria in perennial transmission area.
文摘WORI is the Production-Oriented Approach to reading in the TEFL context of China. It is intended to enhance English learners＇ proficiency in writing and reading. By asking questions to draw learners＇ attention to the professional writers＇ choices concerning organization, development, style, and diction, teachers explicitly guide learners to observe, analyze, study, apperceive, so as to learn about their writing thinking and strategies. By designing a variety of reading-to-write tasks, teachers endeavour to activate learners＇ writing thinking developed in writing-oriented reading activities to have such writing thinking fixed in mind and internalized. The WORI also fosters English learners＇ autonomy of sustaining development in reading, writing, as well as their English learning.
基金supported by the National Natural Science Foundation of China (Grant No. 50671042)the Open Project of State Key Laboratory of Applied Optics (Changchun Institute of Optics,Fine Mechanics and Physics,Chinese Academy of Sciences) (Grant No. 201004)the Ph.D.Innovation Programs Foundation of Jiangsu Province (Grant No.CXZZ12_0671)
文摘In this work,the microstructure and optical properties of the Mo/Si multilayers mirror for the space extreme-ultraviolet solar telescope before and after 100 keV proton irradiation have been investigated.EUV/soft X-ray reflectometer(EXRR) results showed that,after proton irradiation,the reflectivity of the Mo/Si multilayer decreased from 12.20% to 8.34% and the center wavelength revealed red shift of 0.38 nm,as compared with those before proton irradiation.High-resolution transmission electron microscopy(HRTEM) observations revealed the presence of MoSi 2,Mo 3 Si and Mo 5 Si 3 in Mo-on-Si interlayers before irradiation.The preferred orientation such as MoSi 2 with(101) texture and Mo 5 Si 3 with(310) texture was formed in Mo-on-Si interlayers after proton irradiation,which led to the increase of thickness in the interlayers.It is suggested that the changes of microstructures in Mo/Si multilayers under proton irradiation could cause optical properties degradation.
文摘The incidence and mortality of cancer have been increasing alarmingly in China and worldwide.Unlike other chronic diseases such as metabolic,cardiovascular,and neuropathies,most cancers,especially metastatic ones,are still essentially uncontrollable in spite of significant progresses such as early diagnosis and immunotherapies.
