The left-hand superluminous electromagnetic waves, L-O mode and L-X mode, can be excited and observed in the auroral cavity of the Earth during the magnetic storms. The two modes can propagate into outer radiation zon...The left-hand superluminous electromagnetic waves, L-O mode and L-X mode, can be excited and observed in the auroral cavity of the Earth during the magnetic storms. The two modes can propagate into outer radiation zone and encounter enhanced resonant interactions with the trapped energetic electrons over a wide range of magnetosphere. A current first-order resonant model is extended to evaluate the stochastic acceleration of electrons by the L-O mode and L-X mode at the higher-order resonance. Similar to the first-order resonance, L-O mode can produce significant acceleration of electrons at the higher harmonic resonances over a wide range of wave normal angles and spatial regions. However, the higher harmonic resonance＇s contribution for significant electron acceleration by L-X mode is less than that of the first order resonance, with the requirement of higher minimum energies, e.g., -1 MeV in the outer radiation belt. This indicates that L-O mode may be one of the efficient mechanisms for the stochastic acceleration of electrons within the outer radiation zone.展开更多
The effect of the azimuthal angle φ of the wave vector k on the propagation characteristics of the superluminous L-O mode waves （together with a case of the R-X mode） during different geomagnetic activities using a...The effect of the azimuthal angle φ of the wave vector k on the propagation characteristics of the superluminous L-O mode waves （together with a case of the R-X mode） during different geomagnetic activities using a three-dimensional （3D） ray-tracing method is investigated. This work is primarily an extension of our previous two-dimensional study in which the wave azimuthal angle was not considered. We present numerical simulations for this mode which is generated in the source cavity along a 70° night geomagnetic field line at the specific altitude of 1.5RE （where RE is the Earth＇s radius）. It is found that, as in the two-dimensional case, the trajectory of L-O mode starting in the source meridian plane （or the wave azimuthal angle φ = 180°） can reach the lowest latitude; whereas it basically stays at relatively higher latitudes starting off the source meridian plane （or φ=180°）. The results reveal that under appropriate conditions, the superluminous L-O mode waves may exist in the radiation belts of the Earth, but this remains to be supplemented by observational data.展开更多
Purpose： Distal radial fracture is one of the most common fractures. Up to now, locking plates （LP） and external fixation （EF） are two conventional surgical approaches to type C radius fracture. Which method is s...Purpose： Distal radial fracture is one of the most common fractures. Up to now, locking plates （LP） and external fixation （EF） are two conventional surgical approaches to type C radius fracture. Which method is superior has not yet reached a consensus. We try to assess the clinical effectiveness of the two in- terventions by this meta-analysis. Methods： We used network to search the PubMed, Embase, and Cochrane Medical Library of randomized controlled clinical trials about the type C distal radius fractures performed according to the search strategy mentioned in Cochrane Handbook 5.1.0 from Jan. 2005 to Jan. 2016. Patients in the experimental group were used LP, in the control group were included EF and other surgical approaches. Publication language was restricted to English. Studies that patient population and surgical indication did not define had been excluded. Studies must report at least one of the outcomes as follow： radial inclination, patmar tilt, ulnar variance, range of wrist flexion and extension, and range of wrist supination and pronation. The trials in which participants included children were excluded. We used Jadad study scores to appraise the study. Results： Seven studies included 162 patients （LP group） and 190 patients （EF group）. We compared the radial inclination, palmar tilt, ulnar variance, range of wrist flexion and extension, and range of wrist supination and pronation. The radial inclination were revealed a difference favoring LP over EF [WMD = 1.84, 95% CI （0.17, 3.50）, p = 0.03] and the palmar tilt and ulnar variance was no significant difference between the two groups [（WMD = 3.61, 95% CI （0.00, 7.23）, p = 0.05; WMD = 0.05, 95% CI （-0.99,1.09）, p = 0.93]. The functional activities of range of flexion and extension and range of supination and pronation between the two groups was no difference [WMD = 10.04, 95% CI （-6.88, 26.96）, p = 0.24; WMD = 12.53, 95% CI （-9.99, 35.06）, p = 0.28]. Conclusion： Locking plate and external fixation is fe展开更多
特征提取和健康状态的辨识是复杂系统健康状态评估中的关键问题。提出一种新的健康状态评估方法,该方法分为3个步骤:首先,采用经验模态分解(empirical model decomposition,EMD)和奇异值分解(singular value decomposition,SVD)来提取...特征提取和健康状态的辨识是复杂系统健康状态评估中的关键问题。提出一种新的健康状态评估方法,该方法分为3个步骤:首先,采用经验模态分解(empirical model decomposition,EMD)和奇异值分解(singular value decomposition,SVD)来提取振动信号的特征变量。然后,运用马田系统(Mahalanobis-Taguchi system,MTS)构造马氏空间,并对其进行优化,从而降低特征变量的维度。最后,提出了一种健康度(health index,HI)的概念,并且用来对复杂系统健康问题进行评估。该方法成功地应用在轴承的健康状态评估中。展开更多
基金The project supported by National Natural Science Foundation of China (Nos. 40336052, 40274050, and 40474064)Outstanding Youth Foundation of Education Bureau of Hunan Province (No. 04B003)
文摘The left-hand superluminous electromagnetic waves, L-O mode and L-X mode, can be excited and observed in the auroral cavity of the Earth during the magnetic storms. The two modes can propagate into outer radiation zone and encounter enhanced resonant interactions with the trapped energetic electrons over a wide range of magnetosphere. A current first-order resonant model is extended to evaluate the stochastic acceleration of electrons by the L-O mode and L-X mode at the higher-order resonance. Similar to the first-order resonance, L-O mode can produce significant acceleration of electrons at the higher harmonic resonances over a wide range of wave normal angles and spatial regions. However, the higher harmonic resonance＇s contribution for significant electron acceleration by L-X mode is less than that of the first order resonance, with the requirement of higher minimum energies, e.g., -1 MeV in the outer radiation belt. This indicates that L-O mode may be one of the efficient mechanisms for the stochastic acceleration of electrons within the outer radiation zone.
基金National Natural Science Foundation of China(Nos.40774078,40774077)the Chinese Academy of Sciences(No.KZCX3-SW-144)
文摘The effect of the azimuthal angle φ of the wave vector k on the propagation characteristics of the superluminous L-O mode waves （together with a case of the R-X mode） during different geomagnetic activities using a three-dimensional （3D） ray-tracing method is investigated. This work is primarily an extension of our previous two-dimensional study in which the wave azimuthal angle was not considered. We present numerical simulations for this mode which is generated in the source cavity along a 70° night geomagnetic field line at the specific altitude of 1.5RE （where RE is the Earth＇s radius）. It is found that, as in the two-dimensional case, the trajectory of L-O mode starting in the source meridian plane （or the wave azimuthal angle φ = 180°） can reach the lowest latitude; whereas it basically stays at relatively higher latitudes starting off the source meridian plane （or φ=180°）. The results reveal that under appropriate conditions, the superluminous L-O mode waves may exist in the radiation belts of the Earth, but this remains to be supplemented by observational data.
文摘Purpose： Distal radial fracture is one of the most common fractures. Up to now, locking plates （LP） and external fixation （EF） are two conventional surgical approaches to type C radius fracture. Which method is superior has not yet reached a consensus. We try to assess the clinical effectiveness of the two in- terventions by this meta-analysis. Methods： We used network to search the PubMed, Embase, and Cochrane Medical Library of randomized controlled clinical trials about the type C distal radius fractures performed according to the search strategy mentioned in Cochrane Handbook 5.1.0 from Jan. 2005 to Jan. 2016. Patients in the experimental group were used LP, in the control group were included EF and other surgical approaches. Publication language was restricted to English. Studies that patient population and surgical indication did not define had been excluded. Studies must report at least one of the outcomes as follow： radial inclination, patmar tilt, ulnar variance, range of wrist flexion and extension, and range of wrist supination and pronation. The trials in which participants included children were excluded. We used Jadad study scores to appraise the study. Results： Seven studies included 162 patients （LP group） and 190 patients （EF group）. We compared the radial inclination, palmar tilt, ulnar variance, range of wrist flexion and extension, and range of wrist supination and pronation. The radial inclination were revealed a difference favoring LP over EF [WMD = 1.84, 95% CI （0.17, 3.50）, p = 0.03] and the palmar tilt and ulnar variance was no significant difference between the two groups [（WMD = 3.61, 95% CI （0.00, 7.23）, p = 0.05; WMD = 0.05, 95% CI （-0.99,1.09）, p = 0.93]. The functional activities of range of flexion and extension and range of supination and pronation between the two groups was no difference [WMD = 10.04, 95% CI （-6.88, 26.96）, p = 0.24; WMD = 12.53, 95% CI （-9.99, 35.06）, p = 0.28]. Conclusion： Locking plate and external fixation is fe
文摘特征提取和健康状态的辨识是复杂系统健康状态评估中的关键问题。提出一种新的健康状态评估方法,该方法分为3个步骤:首先,采用经验模态分解(empirical model decomposition,EMD)和奇异值分解(singular value decomposition,SVD)来提取振动信号的特征变量。然后,运用马田系统(Mahalanobis-Taguchi system,MTS)构造马氏空间,并对其进行优化,从而降低特征变量的维度。最后,提出了一种健康度(health index,HI)的概念,并且用来对复杂系统健康问题进行评估。该方法成功地应用在轴承的健康状态评估中。
