西藏高原 广州地区f0E,f0Es,fbEs的某些变化特征

本文利用西藏、广州地区1985—1988年夏季的7、8月份的实测资料,对电离层特征参数,f_oE,f_oE_s,f_bE_s,进行了统计分析,得到它们的变化规律与特点。 从图1中看出,西藏高原地区的f_oE值,其变化规律,受太阳黑子的影响较大且为正     

IRI-90及其与中国电离层资料f_0F_2的比较

本文介绍了国际参考电离层IRI-90版中新增的内容,比较了它与IRI-86的主要差别。与我国电离层临频数据的统计分析表明,新版本对我国地区的适用程度有了改进。     

SHIPDES ＊ EDI──基于OSI模式的EDI应用系统

论述了ＥＤＩ的构造原理以及应用发展前景，并介绍了一种基于ＯＳＩ模式、建立在Ｃｈｉｎａｐａｃ公共数据交换网基础上，用于船舶货运单证电子数据交换的可进行发送、存贮和接收电子数据的ＥＤＩ应用系统ＳＨＩＰＤＥＳ＊ＥＤＩ。     

低速风洞数据采集与处理系统

对低速风洞数据采集与处理系统作了综合介绍，该系统以先进的电子扫描压力测量仪器为主体，高性能微机为系统控制处理机，配制高精度模拟量采集部件和前置通道放大器，灵活实用的软件，系统具有同时进行测力测压试验的能力。该系统提供压力联机校正，模拟量通道标准信号校正功能，整个系统的设计包括了许多先进的仪器概念如：电子扫描测压，模拟量信号调理等。该系统具有采集速度快，高稳定性，软硬件功能齐全，实时数据处理，快速提     

A MLP neural network as an investigator of TEC time series to detect seismo-ionospheric anomalies

Anomaly detection is extremely important for earthquake parameters estimation. In this paper, an application of Artificial Neural Networks (ANNs) in the earthquake precursor’s domain has been developed. This study is concerned with investigating the Total Electron Content (TEC) time series by using a Multi-Layer Perceptron (MLP) neural network to detect seismo-ionospheric anomalous variations induced by the powerful Tohoku earthquake of March 11, 2011.     

Kalman filter based estimation of differential hardware biases with triangular interpolation technique for IRNSS

Ionosphere delay correction is the main error correction to the computation of single frequency user position using satellite navigation. However ionosphere delay consists of not only delay but also frequency dependent differential hardware biases from satellite and receiver ends. For ionosphere point of view, Indian Regional Navigation Satellite System (IRNSS) service area comes in equatorial anomaly region. It is a unique satellite navigation system which operates at L5 and S frequencies and consists of Geostationary Earth Orbit (GEO) and Geo Synchronous Orbit (GSO) satellite constellation. With IRNSS measurements availability, there is a good opportunity to estimate and analyse differential hardware biases with GEO/GSO combination and with equatorial ionosphere variation. In this paper, Kalman filter based estimation with triangular interpolation technique is used to estimate differential hardware biases for all IRNSS satellites and reference receivers at L5 frequency. The standard deviation of the 15?days of daily estimation of satellite differential hardware biases is in the range of 0.32 to 1.17 TECU for all IRNSS satellites. Similarly, the standard deviation of the 15?days of daily estimation varies up to 2.85 and 6.0 TECU for receiver differential hardware biases during calm and stormy period respectively. The ionosphere delay computed using estimated differential hardware biases is compared with Global Ionosphere Map (GIM) data. A rigorous analysis is carried out to study the error in the estimation in terms of input data noise level, satellite constellation and effect of latitude. Our result reveals that over IRNSS service area, there is an exponential increase in the error in the estimation of receiver differential hardware biases with respect to latitude.     

Estimation of probability of occurrence of F1 layer or L condition using tables and electron density profile models

An algorithm is proposed for evaluation of the probability of occurrence of an F1 layer or L condition, based on tables. Observations independent of the tables database are used for comparison between the estimated probability of occurrence, the formulation used at present in IRI, and the occurrence actually observed. The importance of the inclusion of L condition in the electron density profile model is shown.     

Plasmaspheric electron content derived from GPS TEC and FORMOSAT-3/COSMIC measurements: Solar minimum condition

The plasmaspheric electron content (PEC) was estimated by comparison of GPS TEC observations and FORMOSAT-3/COSMIC radio occultation measurements at the extended solar minimum of cycle 23/24. Results are retrieved for different seasons (equinoxes and solstices) of the year 2009. COSMIC-derived electron density profiles were integrated up to the height of 700 km in order to retrieve estimates of ionospheric electron content (IEC). Global maps of monthly median values of COSMIC IEC were constructed by use of spherical harmonics expansion. The comparison between two independent measurements was performed by analysis of the global distribution of electron content estimates, as well as by selection specific points corresponded to mid-latitudes of Northern America, Europe, Asia and the Southern Hemisphere. The analysis found that both kinds of observations show rather similar diurnal behavior during all seasons, certainly with GPS TEC estimates larger than corresponded COSMIC IEC values. It was shown that during daytime both GPS TEC and COSMIC IEC values were generally lower at winter than in summer solstice practically over all specific points. The estimates of PEC (h > 700 km) were obtained as a difference between GPS TEC and COSMIC IEC values. Results of comparative study revealed that for mid-latitudinal points PEC estimates varied weakly with the time of a day and reached the value of several TECU for the condition of solar minimum. Percentage contribution of PEC to GPS TEC indicated the clear dependence from the time with maximal values (more than 50–60%) during night-time and lesser values (25–45%) during day-time.     

A study of occurrence characteristics of plasma bubbles over Hong Kong area

Plasma bubble is one of the important weather events of the ionosphere. In past research, many studies on its occurrence characteristics have been done based on various observations, such as ionosondes, topside sounders, radio scintillations and in situ measurements by satellites. In recent years, GPS has become an important tool for the studies in this aspect. In this research, a study is made on occurrence characteristics of plasma bubbles with the GPS observations collected by the Hong Kong local GPS network for about 12 years.