An improved Gaussian mixture model （GMM）- based clustering method is proposed for the difficult case where the true distribution of data is against the assumed GMM. First, an improved model selection criterion, the ...An improved Gaussian mixture model （GMM）- based clustering method is proposed for the difficult case where the true distribution of data is against the assumed GMM. First, an improved model selection criterion, the completed likelihood minimum message length criterion, is derived. It can measure both the goodness-of-fit of the candidate GMM to the data and the goodness-of-partition of the data. Secondly, by utilizing the proposed criterion as the clustering objective function, an improved expectation- maximization （EM） algorithm is developed, which can avoid poor local optimal solutions compared to the standard EM algorithm for estimating the model parameters. The experimental results demonstrate that the proposed method can rectify the over-fitting tendency of representative GMM-based clustering approaches and can robustly provide more accurate clustering results.展开更多
In order to determine the reasonable completed dead load state in earth-anchored cable-stayed bridges,a practical method is proposed. The method is based on the rigidly supported continuous beam method and the feasibl...In order to determine the reasonable completed dead load state in earth-anchored cable-stayed bridges,a practical method is proposed. The method is based on the rigidly supported continuous beam method and the feasible zone method,emphasizing on the mutual effect between the self-anchored structural parts and the earth-anchored ones. Three cable-stayed bridge models are designed with the main spans of 1 400 m,including a partially earth-anchored cable-stayed bridge,a cable-stayed-suspension bridge and a fully selfanchored cable-stayed bridge,in which the C50 concrete and Q345 steel are adopted. The partially earthanchored cable-stayed bridge and the cable-stayed-suspension bridge secure lower compressive force in the girder than the fully self-anchored cable-stayed bridge by 25 percent at least. The same is for the material consumption of the whole bridge. Furthermore,the anchor volume is more than 20% lower in the partially earthanchored cable-stayed bridge than that in the cable-stayed-suspension bridge. Consequently,the practical span of cable-stayed bridges can be accordingly extended.展开更多
In order to quantitatively study the seismic absorption effect of the cushion on a superstructure, a numerical simulation and parametric study are carried out on the overall FEA model of a rigid-pile composite foundat...In order to quantitatively study the seismic absorption effect of the cushion on a superstructure, a numerical simulation and parametric study are carried out on the overall FEA model of a rigid-pile composite foundation in ABAQUS. A simulation of a shaking table test on a rigid mass block is first completed with ABAQUS and EERA, and the effectiveness of the Drucker-Prager constitutive model and the finite-infinite element coupling method is proved. Dynamic time-history analysis of the overall model under frequent and rare earthquakes is carried out using seismic waves from the El Centro, Kobe, and Bonds earthquakes. The different responses of rigid-pile composite foundations and pile-raft foundations are discussed. Furthermore, the influence of thickness and modulus of cushion, and ground acceleration on the seismic absorption effect of the cushion are analyzed. The results show that： 1） the seismic absorption effect of a cushion is good under rare earthquakes, with an absorption ratio of about 0.85; and 2） the seismic absorption effect is strongly affected by cushion thickness and ground acceleration.展开更多
A hydro-dynamic model is established on basis of MIKE21 FM to simulate the hydro-dynamic characteristics of Xinghua Bay and investigate the influence of reclamation project on the tidal elevation and tidal currents. T...A hydro-dynamic model is established on basis of MIKE21 FM to simulate the hydro-dynamic characteristics of Xinghua Bay and investigate the influence of reclamation project on the tidal elevation and tidal currents. Tidal elevation data was obtained at the six tide gauge stations around the Xinghua Bay, and another six current stations were established to observe the tidal current velocity and direction. Validation shows that the model-simulated tidal elevation and tidal currents agree well with observations made at different stations. Predictions are made according to the reclamation project proposed in the regional marine planning of Hanjiang Industrial Park around the port in Putian City. The variations of hydro-dynamic factors, such as tide, current velocity and direction and tidal influx are obtained, and the adverse effect of reclamation on marine environment is discussed. It is shown that the tidal level inside the Xinghua Bay during high tide decreases after the reclamation project is completed. The tidal currents during flooding tide generally decrease in the southeast of the reclamation region, with the maximum decreasing amplitude reaching 0.44 m s^(-1). On the other hand, the tidal currents during flooding tide increase around the southeast and southwest corners of the reclamation region. The tidal currents during ebb tide increase around the southeast and southwest corners of the reclamation region, with the maximum increasing amplitude attaining 0.18 m s^(-1). The results in this paper can give some guidance for the marine environment management and the effective utilization of land in Putian.展开更多
In these pages in December 2016 [1 ], it was noted that the United States and China, representing together 38% of global greenhouse gas emissions, agreed in September 2016 to join the Paris Agreement [2,3] and that, o...In these pages in December 2016 [1 ], it was noted that the United States and China, representing together 38% of global greenhouse gas emissions, agreed in September 2016 to join the Paris Agreement [2,3] and that, on November 4, 2016, the required ratifications were reached in order to put the agreement in force [4].展开更多
Under the condition of normal strength and stress with unknown distribution parameters but getting a completed sample respectively, a comparison among the errors of some kinds of approximate limits for structural reli...Under the condition of normal strength and stress with unknown distribution parameters but getting a completed sample respectively, a comparison among the errors of some kinds of approximate limits for structural reliability has been made in this paper, basing on the exact limits presented. All results in this paper can be used with condition logical normal distribution conveniently.展开更多
BACKGROUND An atrial septal defect is a common condition and accounts for 25%of adult congenital heart diseases.Transcatheter occlusion is a widely used technique for the treatment of secondary aperture-type atrial se...BACKGROUND An atrial septal defect is a common condition and accounts for 25%of adult congenital heart diseases.Transcatheter occlusion is a widely used technique for the treatment of secondary aperture-type atrial septal defects(ASDs).CASE SUMMARY A 30-year-old female patient was diagnosed with ASD by transthoracic echocardiography(TTE)1 year ago.The electrocardiogram showed a heart rate of 88 beats per minute,normal sinus rhythm,and no change in the ST-T wave.After admission,TTE showed an atrial septal defect with a left-to-right shunt,aortic root short-axis section with an ASD diameter of 8 mm,a parasternal four-chamber section with an ASD diameter of 9 mm,and subxiphoid biatrial section with a diameter of 13 mm.Percutaneous occlusion was proposed.The intraoperative TTE scan showed that the atrial septal defect was oval in shape,was located near the root of the aorta,and had a maximum diameter of 13 mm.A 10-F sheath was placed in the right femoral vein,and a 0.035°hard guidewire was used to establish the transport track between the left pulmonary vein and the inferior vena cava.A shape-memory alloy atrial septal occluder with a waist diameter of 20 mm was placed successfully and located correctly.TTE showed that the double disk unfolded well and that the clamping of the atrial septum was smooth.Immediately after the disc was revealed,electrocardiograph monitoring showed that the ST interval of the inferior leads was prolonged,the P waves and QRS waves were separated,a junctional escape rhythm maintained the heart rate,and the blood pressure began to decrease.After removing the occluder,the elevation in the ST segment returned to normal immediately,and the sinus rhythm returned to average approximately 10 min later.After consulting the patient’s family,we finally decided to withdraw from the operation.CONCLUSION Compression of the small coronary artery,which provides an alternative blood supply to the atrioventricular nodule during the operation,leads to the emergence of a complete atrioventricular block.展开更多
After the space lab missions and extended experiments were completed,the Tianzhou 1 cargo spacecraft effectively put on its'breaks'twice,thus continuously lowering its altitude before burning-up in the atmosph...After the space lab missions and extended experiments were completed,the Tianzhou 1 cargo spacecraft effectively put on its'breaks'twice,thus continuously lowering its altitude before burning-up in the atmosphere around 6p.m.on September 22.Tianzhou 1 was China’s first cargo spacecraft developed by CASC,launched on April 20 from the Hainan Wenchang Spacecraft Launch Site.Tianzhou 1,signified the end of展开更多
Little is known about the association between parity and the risk of ovarian cysts. The aim of this study was to examine the association between parity and the risk of ovarian cysts among a population of Chinese women...Little is known about the association between parity and the risk of ovarian cysts. The aim of this study was to examine the association between parity and the risk of ovarian cysts among a population of Chinese women. A total of 20 502 women aged 45–86 years from the Dongfeng-Tongji Cohort study completed baseline questionnaires, medical examination and provided baseline blood samples. Participants were categorized into four groups according to parity（one, two, three, and four or more live births）. Logistic regression models were used to investigate the association between parity and the risk of ovarian cysts. The prevalence of ovarian cysts in the study population was 4.0%（816/20 502）. Increasing parity was associated with decreasing risk of ovarian cysts without adjustment for any covariates and after age-adjusted model（P〈0.001）. After adjusting for potential confounders, women who had had four or more live births had lower risk of ovarian cysts（OR： 0.51; 95% CI： 0.27–0.96） compared with women who had had one live birth. There was a consistent but non-significant decreased risk of ovarian cysts for women who had had two, and three live births（OR： 0.85; 95% CI： 0.68–1.05） and（OR： 0.84; 95% CI： 0.59–1.20） respectively compared with women who had had one live birth. It was concluded that higher parity was associated with decreasing risk of ovarian cysts in this population of Chinese women. These findings could be helpful in decision making in clinical practice for gynecologists when evaluating women suspected to have ovarian cysts.展开更多
Disorder inevitably exists in realistic samples,manifesting itself in various exotic properties for the topological states.In this paper,we summarize and briefly review the work completed over the last few years,inclu...Disorder inevitably exists in realistic samples,manifesting itself in various exotic properties for the topological states.In this paper,we summarize and briefly review the work completed over the last few years,including our own,regarding recent developments in several topics about disorder effects in topological states.For weak disorder,the robustness of topological states is demonstrated,especially for both quantum spin Hall states with Z2 = 1 and size induced nontrivial topological insulators with Z2 = 0.For moderate disorder,by increasing the randomness of both the impurity distribution and the impurity induced potential,the topological insulator states can be created from normal metallic or insulating states.These phenomena and their mechanisms are summarized.For strong disorder,the disorder causes a metal-insulator transition.Due to their topological nature,the phase diagrams are much richer in topological state systems.Finally,the trends in these areas of disorder research are discussed.展开更多
Technical standardization is very essential to electricity industry, which plays an active role in many aspects including technology standardization, secure and economic operation of power systems, environment protect...Technical standardization is very essential to electricity industry, which plays an active role in many aspects including technology standardization, secure and economic operation of power systems, environment protection, technological progress, and improvement of enterprises' management. This paper introduces the current status of hydroelectricity standardization, summarizes the progress and achievements, and then points out the development direction and working target in the future.展开更多
Aerodynamic force can lead to the strong structural vibration of flying aircraft at a high speed. This harmful vibration can bring damage or failure to the electronic equipment fixed in aircraft. It is necessary to pr...Aerodynamic force can lead to the strong structural vibration of flying aircraft at a high speed. This harmful vibration can bring damage or failure to the electronic equipment fixed in aircraft. It is necessary to predict the structural dynamic response in the design course. This paper presents a new numerical algorithm and scheme to solve the structural dynamics responses when considering fluid–structure interaction（FSI）. Numerical simulation for a free-flying structural model in transonic speed is completed. Results show that the small elastic deformation of the structure can greatly affect the FSI. The FSI vibration tests are carried out in a transonic speed windtunnel for checking numerical theory and algorithms, and the wind-tunnel test results well accord with that of the numerical simulation. This indicates that the presented numerical method can be applied to predicting the structural dynamics responses when containing the FSI.展开更多
The development of the Chinese-French Oceanography Satellite Program is proceeding well,according to China Spacesat Co.,Ltd under China Aerospace Science and Technology Corporation who is in charge of the development ...The development of the Chinese-French Oceanography Satellite Program is proceeding well,according to China Spacesat Co.,Ltd under China Aerospace Science and Technology Corporation who is in charge of the development of the satellite.The interface validation of the prototype phase has been completed and the satellite is expected to enter into flight model phase next year.展开更多
China’s most advanced Earth observation satellite,GF-2,was put into service on March 6,2015.The GF-2 satellite is the second of seven satellites that will be launched for the High Resolution Earth Observation project...China’s most advanced Earth observation satellite,GF-2,was put into service on March 6,2015.The GF-2 satellite is the second of seven satellites that will be launched for the High Resolution Earth Observation project mission before 2020.The project was initiated in May 2010 and GF-1 was展开更多
The ocean-going instrumentations-Yuan Wang,are an important part of the space TT&C networks in China.They have successfully completed 11 missions in the past 20 years.The tasks of these ships are to track and meas...The ocean-going instrumentations-Yuan Wang,are an important part of the space TT&C networks in China.They have successfully completed 11 missions in the past 20 years.The tasks of these ships are to track and measure the flight path data of spacecraft and launch rockets,receive the remote information,transmit the command as well as communicate with and rescue the astronauts reentrying and splashing down over the sea in the futureThe detail characteristics of the Yuan Wang’s structure,the main components,durability,adaptability and stability in various conditions are given in this paper.The shipboard high precision TT&.C equipments include the 180 Monopulse Radar,the 450-3 Remote Telemetry System and the 718 Laser Position Indicator,and their basic compositions and functions are also given.The technical measures to be taken to support the TT&C system are discussed here.展开更多
In the long history of development of human society, people have gradually foundthat some marine living beings could be used as medicines. As early as in 1596 A. D.,LiShizhen, a Chinese scholar of the Ming Dynasty,had...In the long history of development of human society, people have gradually foundthat some marine living beings could be used as medicines. As early as in 1596 A. D.,LiShizhen, a Chinese scholar of the Ming Dynasty,had completed Compendium of MateriaMedia,in which he described 1, 892 kinds of medicines,of which more than 90 are marinemedicines. This book has been highly valued,has become an important part of the tradi-展开更多
After a dozen days of hardwork under extreme conditionsfrom May 25 to June 10, a teamof 20 Chinse scientists returnedfrom Qomolangma (Everest) withair and water samples, and atmos-pheric ozone profile data.
基金The National Natural Science Foundation of China(No.61105048,60972165)the Doctoral Fund of Ministry of Education of China(No.20110092120034)+2 种基金the Natural Science Foundation of Jiangsu Province(No.BK2010240)the Technology Foundation for Selected Overseas Chinese Scholar,Ministry of Human Resources and Social Security of China(No.6722000008)the Open Fund of Jiangsu Province Key Laboratory for Remote Measuring and Control(No.YCCK201005)
文摘An improved Gaussian mixture model （GMM）- based clustering method is proposed for the difficult case where the true distribution of data is against the assumed GMM. First, an improved model selection criterion, the completed likelihood minimum message length criterion, is derived. It can measure both the goodness-of-fit of the candidate GMM to the data and the goodness-of-partition of the data. Secondly, by utilizing the proposed criterion as the clustering objective function, an improved expectation- maximization （EM） algorithm is developed, which can avoid poor local optimal solutions compared to the standard EM algorithm for estimating the model parameters. The experimental results demonstrate that the proposed method can rectify the over-fitting tendency of representative GMM-based clustering approaches and can robustly provide more accurate clustering results.
基金Sponsored by the National Basic Research Program of China(Grant No.2013CB036303)the National Natural Science Foundation of China(Grant No.51008223)
文摘In order to determine the reasonable completed dead load state in earth-anchored cable-stayed bridges,a practical method is proposed. The method is based on the rigidly supported continuous beam method and the feasible zone method,emphasizing on the mutual effect between the self-anchored structural parts and the earth-anchored ones. Three cable-stayed bridge models are designed with the main spans of 1 400 m,including a partially earth-anchored cable-stayed bridge,a cable-stayed-suspension bridge and a fully selfanchored cable-stayed bridge,in which the C50 concrete and Q345 steel are adopted. The partially earthanchored cable-stayed bridge and the cable-stayed-suspension bridge secure lower compressive force in the girder than the fully self-anchored cable-stayed bridge by 25 percent at least. The same is for the material consumption of the whole bridge. Furthermore,the anchor volume is more than 20% lower in the partially earthanchored cable-stayed bridge than that in the cable-stayed-suspension bridge. Consequently,the practical span of cable-stayed bridges can be accordingly extended.
基金This project,No.2011ZA05,is supported by the State Key Laboratory of Subtropical Building Science,South China University of Technology,Guangzhou,China
文摘In order to quantitatively study the seismic absorption effect of the cushion on a superstructure, a numerical simulation and parametric study are carried out on the overall FEA model of a rigid-pile composite foundation in ABAQUS. A simulation of a shaking table test on a rigid mass block is first completed with ABAQUS and EERA, and the effectiveness of the Drucker-Prager constitutive model and the finite-infinite element coupling method is proved. Dynamic time-history analysis of the overall model under frequent and rare earthquakes is carried out using seismic waves from the El Centro, Kobe, and Bonds earthquakes. The different responses of rigid-pile composite foundations and pile-raft foundations are discussed. Furthermore, the influence of thickness and modulus of cushion, and ground acceleration on the seismic absorption effect of the cushion are analyzed. The results show that： 1） the seismic absorption effect of a cushion is good under rare earthquakes, with an absorption ratio of about 0.85; and 2） the seismic absorption effect is strongly affected by cushion thickness and ground acceleration.
基金supported by the Regional Marine Planning of Hanjiang Industrial Park around the port in Putian City
文摘A hydro-dynamic model is established on basis of MIKE21 FM to simulate the hydro-dynamic characteristics of Xinghua Bay and investigate the influence of reclamation project on the tidal elevation and tidal currents. Tidal elevation data was obtained at the six tide gauge stations around the Xinghua Bay, and another six current stations were established to observe the tidal current velocity and direction. Validation shows that the model-simulated tidal elevation and tidal currents agree well with observations made at different stations. Predictions are made according to the reclamation project proposed in the regional marine planning of Hanjiang Industrial Park around the port in Putian City. The variations of hydro-dynamic factors, such as tide, current velocity and direction and tidal influx are obtained, and the adverse effect of reclamation on marine environment is discussed. It is shown that the tidal level inside the Xinghua Bay during high tide decreases after the reclamation project is completed. The tidal currents during flooding tide generally decrease in the southeast of the reclamation region, with the maximum decreasing amplitude reaching 0.44 m s^(-1). On the other hand, the tidal currents during flooding tide increase around the southeast and southwest corners of the reclamation region. The tidal currents during ebb tide increase around the southeast and southwest corners of the reclamation region, with the maximum increasing amplitude attaining 0.18 m s^(-1). The results in this paper can give some guidance for the marine environment management and the effective utilization of land in Putian.
文摘In these pages in December 2016 [1 ], it was noted that the United States and China, representing together 38% of global greenhouse gas emissions, agreed in September 2016 to join the Paris Agreement [2,3] and that, on November 4, 2016, the required ratifications were reached in order to put the agreement in force [4].
文摘Under the condition of normal strength and stress with unknown distribution parameters but getting a completed sample respectively, a comparison among the errors of some kinds of approximate limits for structural reliability has been made in this paper, basing on the exact limits presented. All results in this paper can be used with condition logical normal distribution conveniently.
文摘BACKGROUND An atrial septal defect is a common condition and accounts for 25%of adult congenital heart diseases.Transcatheter occlusion is a widely used technique for the treatment of secondary aperture-type atrial septal defects(ASDs).CASE SUMMARY A 30-year-old female patient was diagnosed with ASD by transthoracic echocardiography(TTE)1 year ago.The electrocardiogram showed a heart rate of 88 beats per minute,normal sinus rhythm,and no change in the ST-T wave.After admission,TTE showed an atrial septal defect with a left-to-right shunt,aortic root short-axis section with an ASD diameter of 8 mm,a parasternal four-chamber section with an ASD diameter of 9 mm,and subxiphoid biatrial section with a diameter of 13 mm.Percutaneous occlusion was proposed.The intraoperative TTE scan showed that the atrial septal defect was oval in shape,was located near the root of the aorta,and had a maximum diameter of 13 mm.A 10-F sheath was placed in the right femoral vein,and a 0.035°hard guidewire was used to establish the transport track between the left pulmonary vein and the inferior vena cava.A shape-memory alloy atrial septal occluder with a waist diameter of 20 mm was placed successfully and located correctly.TTE showed that the double disk unfolded well and that the clamping of the atrial septum was smooth.Immediately after the disc was revealed,electrocardiograph monitoring showed that the ST interval of the inferior leads was prolonged,the P waves and QRS waves were separated,a junctional escape rhythm maintained the heart rate,and the blood pressure began to decrease.After removing the occluder,the elevation in the ST segment returned to normal immediately,and the sinus rhythm returned to average approximately 10 min later.After consulting the patient’s family,we finally decided to withdraw from the operation.CONCLUSION Compression of the small coronary artery,which provides an alternative blood supply to the atrioventricular nodule during the operation,leads to the emergence of a complete atrioventricular block.
文摘After the space lab missions and extended experiments were completed,the Tianzhou 1 cargo spacecraft effectively put on its'breaks'twice,thus continuously lowering its altitude before burning-up in the atmosphere around 6p.m.on September 22.Tianzhou 1 was China’s first cargo spacecraft developed by CASC,launched on April 20 from the Hainan Wenchang Spacecraft Launch Site.Tianzhou 1,signified the end of
基金supported by grants from the National Natural Science Foundation of China(No.81273083)the Fundamental Research Funds for the Central Universities(No.2014TS051)
文摘Little is known about the association between parity and the risk of ovarian cysts. The aim of this study was to examine the association between parity and the risk of ovarian cysts among a population of Chinese women. A total of 20 502 women aged 45–86 years from the Dongfeng-Tongji Cohort study completed baseline questionnaires, medical examination and provided baseline blood samples. Participants were categorized into four groups according to parity（one, two, three, and four or more live births）. Logistic regression models were used to investigate the association between parity and the risk of ovarian cysts. The prevalence of ovarian cysts in the study population was 4.0%（816/20 502）. Increasing parity was associated with decreasing risk of ovarian cysts without adjustment for any covariates and after age-adjusted model（P〈0.001）. After adjusting for potential confounders, women who had had four or more live births had lower risk of ovarian cysts（OR： 0.51; 95% CI： 0.27–0.96） compared with women who had had one live birth. There was a consistent but non-significant decreased risk of ovarian cysts for women who had had two, and three live births（OR： 0.85; 95% CI： 0.68–1.05） and（OR： 0.84; 95% CI： 0.59–1.20） respectively compared with women who had had one live birth. It was concluded that higher parity was associated with decreasing risk of ovarian cysts in this population of Chinese women. These findings could be helpful in decision making in clinical practice for gynecologists when evaluating women suspected to have ovarian cysts.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11374219,11474085,and 11534001)the Natural Science Foundation of Jiangsu Province,China(Grant No BK20160007)
文摘Disorder inevitably exists in realistic samples,manifesting itself in various exotic properties for the topological states.In this paper,we summarize and briefly review the work completed over the last few years,including our own,regarding recent developments in several topics about disorder effects in topological states.For weak disorder,the robustness of topological states is demonstrated,especially for both quantum spin Hall states with Z2 = 1 and size induced nontrivial topological insulators with Z2 = 0.For moderate disorder,by increasing the randomness of both the impurity distribution and the impurity induced potential,the topological insulator states can be created from normal metallic or insulating states.These phenomena and their mechanisms are summarized.For strong disorder,the disorder causes a metal-insulator transition.Due to their topological nature,the phase diagrams are much richer in topological state systems.Finally,the trends in these areas of disorder research are discussed.
文摘Technical standardization is very essential to electricity industry, which plays an active role in many aspects including technology standardization, secure and economic operation of power systems, environment protection, technological progress, and improvement of enterprises' management. This paper introduces the current status of hydroelectricity standardization, summarizes the progress and achievements, and then points out the development direction and working target in the future.
基金supported by the National Natural Science Foundation of China(No.50875212)Specialized Research Fund(priority development area)for the Doctoral Program of Higher Education of China(No.20126102130004)
文摘Aerodynamic force can lead to the strong structural vibration of flying aircraft at a high speed. This harmful vibration can bring damage or failure to the electronic equipment fixed in aircraft. It is necessary to predict the structural dynamic response in the design course. This paper presents a new numerical algorithm and scheme to solve the structural dynamics responses when considering fluid–structure interaction（FSI）. Numerical simulation for a free-flying structural model in transonic speed is completed. Results show that the small elastic deformation of the structure can greatly affect the FSI. The FSI vibration tests are carried out in a transonic speed windtunnel for checking numerical theory and algorithms, and the wind-tunnel test results well accord with that of the numerical simulation. This indicates that the presented numerical method can be applied to predicting the structural dynamics responses when containing the FSI.
文摘The development of the Chinese-French Oceanography Satellite Program is proceeding well,according to China Spacesat Co.,Ltd under China Aerospace Science and Technology Corporation who is in charge of the development of the satellite.The interface validation of the prototype phase has been completed and the satellite is expected to enter into flight model phase next year.
文摘China’s most advanced Earth observation satellite,GF-2,was put into service on March 6,2015.The GF-2 satellite is the second of seven satellites that will be launched for the High Resolution Earth Observation project mission before 2020.The project was initiated in May 2010 and GF-1 was
文摘The ocean-going instrumentations-Yuan Wang,are an important part of the space TT&C networks in China.They have successfully completed 11 missions in the past 20 years.The tasks of these ships are to track and measure the flight path data of spacecraft and launch rockets,receive the remote information,transmit the command as well as communicate with and rescue the astronauts reentrying and splashing down over the sea in the futureThe detail characteristics of the Yuan Wang’s structure,the main components,durability,adaptability and stability in various conditions are given in this paper.The shipboard high precision TT&.C equipments include the 180 Monopulse Radar,the 450-3 Remote Telemetry System and the 718 Laser Position Indicator,and their basic compositions and functions are also given.The technical measures to be taken to support the TT&C system are discussed here.
文摘In the long history of development of human society, people have gradually foundthat some marine living beings could be used as medicines. As early as in 1596 A. D.,LiShizhen, a Chinese scholar of the Ming Dynasty,had completed Compendium of MateriaMedia,in which he described 1, 892 kinds of medicines,of which more than 90 are marinemedicines. This book has been highly valued,has become an important part of the tradi-
文摘After a dozen days of hardwork under extreme conditionsfrom May 25 to June 10, a teamof 20 Chinse scientists returnedfrom Qomolangma (Everest) withair and water samples, and atmos-pheric ozone profile data.
