Wideband multiple-input multiple-output (MIMO) channel measurements were performed at5.25GHz in the hotspot environment in Beijing.The propagation mechanism was line-of-sight and ob-structed-line-of-sight (LOS/OLOS) i...Wideband multiple-input multiple-output (MIMO) channel measurements were performed at5.25GHz in the hotspot environment in Beijing.The propagation mechanism was line-of-sight and ob-structed-line-of-sight (LOS/OLOS) in the outdoor scenario.Using a large amount of estimated angle ofdeparture (AoD) and angle of arrival (AoA) results,the cumulative distribution functions (CDFs) of di-rectional spread (DS) are extracted,which illustrate that the spatial dispersion is quite significant at bothends due to the low antenna height of base station and rich scatterers.The average power azimuth spec-trum (PAS) is found to be well fitted with a Laplacian function.In addition,the non-isotropic property ofspatial correlation is investigated,and the average envelop correlation over arbitrary antenna spacing pro-vides the correlation distance to facilitate the MIMO optimization and deployment in the outdoor hotspotenvironment.展开更多
A schematic to make the spectra of the exterior noise of high speed railway was put forward. The exterior noise spectrum was defined based on the characteristics of the high-speed train exterior noise. Its characteris...A schematic to make the spectra of the exterior noise of high speed railway was put forward. The exterior noise spectrum was defined based on the characteristics of the high-speed train exterior noise. Its characteristics considered here include identifying the exterior main sources and their locations, their frequency components including the Doppler effect due to the noise sources moving at high speed, the sound field intensity around the train in high-speed operation, the sound radiation path out of the train, and the pressure level and frequency components of the noise at the measuring points specified by the International Organization for Standardization(ISO). The characteristics of the high-speed train exterior noise of the high speed railways in operation were introduced. The advanced measuring systems and their principles for clearly indentifying the exterior noise sources were discussed in detail. Based on the concerned noise results measured at sites, a prediction model was developed to calculate the sound level and the characteristics of the exterior noise at any point where it is difficult to measure and to help to make the exterior noise spectrums. This model was also verified with the test results. The verification shows that there is a good agreement between the theoretical and experimental results.展开更多
In order to eliminate the impact of the Doppler effects caused by the motion of the spacecraft on the X-ray pulsar-based navigation, an innovative navigation method using the pulse phase and Doppler frequency measurem...In order to eliminate the impact of the Doppler effects caused by the motion of the spacecraft on the X-ray pulsar-based navigation, an innovative navigation method using the pulse phase and Doppler frequency measurements of the X-ray pulsars is proposed. Given the initial estimate of the spacecraft's state,the real-time photon arrival model is established at the spacecraft with respect to the spacecraft's position and velocity predicted by the orbit dynamic model and their estimation errors. On this basis, a maximum likelihood estimation algorithm directly using the observed photon event timestamps is developed to extract a single pair of pulse phase and Doppler frequency measurements caused by the spacecraft's state estimation error. Since the phase estimation error increases as the observation time increases, we propose a new measurement updating scheme of referring the measurements to the middle time of an observation interval. By using the ground-based simulation system of X-ray pulsar signals, a series of photon-level simulations are performed. The results testify to the feasibility and real-timeliness of the proposed navigation method, and show that the incorporation of the Doppler measurement as well as the pulse phase into the navigation filter can improve the navigation accuracy.展开更多
OBJECTIVE:To compare the curative effects of heat-sensitive moxibustion with conventional drugs on chronic persistent asthma and seek a valuable therapy to replaceWestern Medicine.METHODS:The participants in this mult...OBJECTIVE:To compare the curative effects of heat-sensitive moxibustion with conventional drugs on chronic persistent asthma and seek a valuable therapy to replaceWestern Medicine.METHODS:The participants in this multi-center,randomized,and controlled study were randomly divided into two groups:group A(n=144),treated with heat-sensitive moxibustion(50 sessions)and group B(n=144),treated with Seretide(salmeterol50μg/fluticasone 250μg,twice a day).The scores of asthma control test(ACT),forced expiratory volume in 1 second(FEV1),peak expiratory flow(PEF),and attack frequency were measured after 15,30,60,and 90 days of treatment.Patients followed up3 and 6 months after treatment.RESULTS:There was a significant difference(P=0.0002)in the ACT score and lung function between the two groups after 3 months of treatment and(P=0.000 03)during the follow-up visits.In addition,heat-sensitive moxibustion reduced attack frequency in the period from inclusion to the6-month follow-up visit.CONCLUSION:This study shows that heat-sensitive moxibustion may have a comparable curative effect toSeretide(salmeterol/fluticasone)on asthma.展开更多
基金the National High Technology Research and Development Programme of China(No.2006AA01Z258)
文摘Wideband multiple-input multiple-output (MIMO) channel measurements were performed at5.25GHz in the hotspot environment in Beijing.The propagation mechanism was line-of-sight and ob-structed-line-of-sight (LOS/OLOS) in the outdoor scenario.Using a large amount of estimated angle ofdeparture (AoD) and angle of arrival (AoA) results,the cumulative distribution functions (CDFs) of di-rectional spread (DS) are extracted,which illustrate that the spatial dispersion is quite significant at bothends due to the low antenna height of base station and rich scatterers.The average power azimuth spec-trum (PAS) is found to be well fitted with a Laplacian function.In addition,the non-isotropic property ofspatial correlation is investigated,and the average envelop correlation over arbitrary antenna spacing pro-vides the correlation distance to facilitate the MIMO optimization and deployment in the outdoor hotspotenvironment.
基金Project(2682013BR009)supported by the Fundamental Research Funds of the Central Universities,ChinaProject(2011AA11A103-2-2)the National High-Technology Research and Development Program of China
文摘A schematic to make the spectra of the exterior noise of high speed railway was put forward. The exterior noise spectrum was defined based on the characteristics of the high-speed train exterior noise. Its characteristics considered here include identifying the exterior main sources and their locations, their frequency components including the Doppler effect due to the noise sources moving at high speed, the sound field intensity around the train in high-speed operation, the sound radiation path out of the train, and the pressure level and frequency components of the noise at the measuring points specified by the International Organization for Standardization(ISO). The characteristics of the high-speed train exterior noise of the high speed railways in operation were introduced. The advanced measuring systems and their principles for clearly indentifying the exterior noise sources were discussed in detail. Based on the concerned noise results measured at sites, a prediction model was developed to calculate the sound level and the characteristics of the exterior noise at any point where it is difficult to measure and to help to make the exterior noise spectrums. This model was also verified with the test results. The verification shows that there is a good agreement between the theoretical and experimental results.
文摘In order to eliminate the impact of the Doppler effects caused by the motion of the spacecraft on the X-ray pulsar-based navigation, an innovative navigation method using the pulse phase and Doppler frequency measurements of the X-ray pulsars is proposed. Given the initial estimate of the spacecraft's state,the real-time photon arrival model is established at the spacecraft with respect to the spacecraft's position and velocity predicted by the orbit dynamic model and their estimation errors. On this basis, a maximum likelihood estimation algorithm directly using the observed photon event timestamps is developed to extract a single pair of pulse phase and Doppler frequency measurements caused by the spacecraft's state estimation error. Since the phase estimation error increases as the observation time increases, we propose a new measurement updating scheme of referring the measurements to the middle time of an observation interval. By using the ground-based simulation system of X-ray pulsar signals, a series of photon-level simulations are performed. The results testify to the feasibility and real-timeliness of the proposed navigation method, and show that the incorporation of the Doppler measurement as well as the pulse phase into the navigation filter can improve the navigation accuracy.
基金Supported by the Major State Basic Research and Development Program of People's Republic of China(No.2009CB522902)National Key Technology R&D Program(No.2006BAI12B04-2)+2 种基金National Natural Science Foundation of China(No.81160453)National Natural Science Foundation of China(No.81202854)Jiangxi Key R&D Project
文摘OBJECTIVE:To compare the curative effects of heat-sensitive moxibustion with conventional drugs on chronic persistent asthma and seek a valuable therapy to replaceWestern Medicine.METHODS:The participants in this multi-center,randomized,and controlled study were randomly divided into two groups:group A(n=144),treated with heat-sensitive moxibustion(50 sessions)and group B(n=144),treated with Seretide(salmeterol50μg/fluticasone 250μg,twice a day).The scores of asthma control test(ACT),forced expiratory volume in 1 second(FEV1),peak expiratory flow(PEF),and attack frequency were measured after 15,30,60,and 90 days of treatment.Patients followed up3 and 6 months after treatment.RESULTS:There was a significant difference(P=0.0002)in the ACT score and lung function between the two groups after 3 months of treatment and(P=0.000 03)during the follow-up visits.In addition,heat-sensitive moxibustion reduced attack frequency in the period from inclusion to the6-month follow-up visit.CONCLUSION:This study shows that heat-sensitive moxibustion may have a comparable curative effect toSeretide(salmeterol/fluticasone)on asthma.
