In this paper, using the observational data of ACE satellite, ionosonde and GPS TEC, the authors analyze the ionospheric storm during 19-22 March 2001. The results show that the interplanetary environment induced by the coronal mass ejection (CME) provides the large scale background for the ionospheric storm. The strong negative ionospheric storm occurs in the recovery phase of the geomagnetic storm. And the mechanism of the negative ionospheric storm is consistent with the storm ring theory.
The Doppler shift of radio wave echoes reflected from ionosphere is an important parameter to observe ionospheric movements. Generally, high resolution Doppler shift could be obtained in drift mode with digital ionosonde. In this mode, only a few working frequencies are used, so ionospheric disturbance profile with height cannot be acquired. However, in ionogram mode, though Digisonde works with many sounding frequencies, the resolution of Doppler shift is too low to detect ionospheric disturbances precisely. In this paper, a new analysis method is given based on the fact of narrow band of ionospheric echoes, through converting sixteen Doppler channel data to temporal domain by IDFT and estimating the phase differences of adjacent time by least square method, the high accurate doppliono-gram could be acquired in ionogram mode. In order to prove the effectiveness of the method, some experiments have been carried out with Digisonde-256 at Wuhan Ionospheric Observatory. The experimental results have revealed that the high accurate Dopplionogram can be acquired, and the present method is very useful in experimental investigation of ionospheric disturbances.
This paper discusses chaotic properties of ionospheric total electron content (TEC) based on the TEC data from 1996 to 2004, and analyzes possibility to predict it by using the chaos theory. Calculation shows that the TEC chaos properties over a specified area exist. The correlation dimension is 3.6092 and the Lyapumov exponent is 0.3369. It is successful to predict TEC by using the weighted one-rank local-region forecasting model. Analysis of the forecasting error indicates that the error is lesser comparatively among 1 similar to 144 forecasted points, while the standard deviation is about 7.6438 TECU and the correlation coefficient is about 0.9172.
Objective To compare the diagnostic values of rest 99Tcm-MIBI MPI and two-dimensional echocardiography (2-DE) for the detection of coronary artery damage at sub-acute phase of Kawasaki disease (KD).Methods Twenty-four children (14 males and 10 females,mean age:(2.50±2.19)years) with KD at sub-acute phase were studied between August 1999 and March 2012.All patients underwent rest 99Tcm-MIBI MPI and 2-DE.x2 and Wilcoxon rank sum tests with SPSS 13.0 were used for data analysis.Results The positive rate of MPI was 66.67％ (16/24),significantly higher than that of 2-DE (37.50％,9/24; x2 =4.00,P＜0.05).There was no significant difference between the duration for definite diagnosis by MPI and 2-DE ((13.79±2.86) vs (15.89±5.60) d; Z=-0.746,P＞0.05).Eight of 24 patients (33.33％) had positive results for both MPI and 2-DE,and 7 patients (29.17％) had negative findings for both methods.Eight patients (8/24,33.33％) were positive on MPI but negative on 2-DE,and 1 patient (1/24,4.17％) was positive on 2-DE but negative on MPI.The areas of myocardial ischemia detected by MPI in 4 patients were consistent with the findings by 2-DE.Conclusions Rest 99Tcm-MIBI MPI is a valuable noninvasive method to evaluate the coronary circulation and myocardial ischemia in KD patients at sub-acute phase.In combination with MPI,2-DE might provide more comprehensive information for the evaluation of KD.
Key words:
Mucocutaneous lymph node syndrome; Coronary disease; Tomography,emission-computed, single-photon; Echocardiography; MIBI
Based on the International Reference Ionosphere model (IRI) and the correcting model of ionosphere time delay, this paper has given the space-time distributing of ionosphere time delay in our territory and the error of correcting model with numerical study.
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