Behavior of the equivalent slab thickness over three European stations

The total electron content (TEC) derived from the global positioning system (GPS) and the F2-layer peak electron density obtained from Digisonde data have been used to study the diurnal, seasonal and solar activity variations of the ionospheric equivalent slab thickness (τ) over three European stations located at Pruhonice (50.0°N, 15.0°E), Ebro (40.8°N, 0.5°E) and El Arenosillo (37.1°N, 353.3°E). The diurnal variation of the τ is characterized by daytime values lower than nighttime ones for all seasons at low solar activity while daytime values larger than nighttime characterizes the diurnal variation for summer at high solar activity. A double peak is noticeable at dusk and at dawn, better expressed for winter at low solar activity. The seasonal variations of τ depend on local time and solar activity, the daytime values of τ increases from winter to summer whereas nighttime values of τ show the opposite. The effect of the solar activity on τ depends on local time and season, there being very sensitive for winter nighttime values of τ. The results of this study are compared with those presented by other authors.     

Comparative study of foF2 measurements with IRI-2007 model predictions during extended solar minimum

The unusually deep and extended solar minimum of cycle 23/24 made it very difficult to predict the solar indices 1 or 2 years into the future. Most of the predictions were proven wrong by the actual observed indices. IRI gets its solar, magnetic, and ionospheric indices from an indices file that is updated twice a year. In recent years, due to the unusual solar minimum, predictions had to be corrected downward with every new indices update. In this paper we analyse how much the uncertainties in the predictability of solar activity indices affect the IRI outcome and how the IRI values calculated with predicted and observed indices compared to the actual measurements. Monthly median values of F2 layer critical frequency (foF2) derived from the ionosonde measurements at the mid-latitude ionospheric station Juliusruh were compared with the International Reference Ionosphere (IRI-2007) model predictions. The analysis found that IRI provides reliable results that compare well with actual measurements, when the definite (observed and adjusted) indices of solar activity are used, while IRI values based on earlier predictions of these indices noticeably overestimated the measurements during the solar minimum. One of the principal objectives of this paper is to direct attention of IRI users to update their solar activity indices files regularly. Use of an older index file can lead to serious IRI overestimations of F-region electron density during the recent extended solar minimum.     

低功耗数字气压计的设计

介绍了一种低功耗数字气压计的软硬件实现方法。通过气压传感器获得与大气压相对应的模拟电压值,并经过A/D变换输入到单片机进行处理,从而实时显示相应的气压值。通过休眠或掉电的方式降低了仪器的耗电量,使用一支高容量锂/亚硫酰氯电池供电可以连续使用8年以上。     

电压／频率变换电路实现A／D转换

数据的采集与处理广泛的应用在自动化领域中,由于应用的场合不同,对数据采集与处理所要求的精度也不相同。考虑到测量精度要求,详细的阐述了以MSP430F149为主控芯片的系统软硬件的研究、设计和实现,介绍了如何采用压控振荡器LM331与控制器MSP430F149内部Timer模块构成ADC,即线性放电法（威尔金逊法）ADC。     

Multi-station observation of ionospheric irregularities over South Africa during strong geomagnetic storms

This paper presents results pertaining to the response of the mid-latitude ionosphere to strong geomagnetic storms that occurred from 31 March to 02 April 2001 and 07–09 September 2002. The results are based on (i) Global Positioning Systems (GPSs) derived total electron content (TEC) variations accompanying the storm, (ii) ionosonde measurements of the ionospheric electrodynamic response towards the storms and (iii) effect of storm induced travelling ionospheric disturbances (TIDs) on GPS derived TEC. Ionospheric data comprising of ionospheric TEC obtained from GPS measurements, ionograms, solar wind data obtained from Advanced Composition Explorer (ACE) and magnetic data from ground based magnetometers were used in this study. Storm induced features in vertical TEC (VTEC) have been obtained and compared with the mean VTEC of quiet days. The response of the mid-latitude ionosphere during the two storm periods examined may be characterised in terms of increased or decreased level of VTEC, wave-like structures in VTEC perturbation and sudden enhancement in hmF2 and h′F. The study reveals both positive and negative ionospheric storm effects on the ionosphere over South Africa during the two strong storm conditions. These ionospheric features have been mainly attributed to the travelling ionospheric disturbances (TIDs) as the driving mechanism for the irregularities causing the perturbations observed. TEC perturbations due to the irregularities encountered by the satellites were observed on satellites with pseudo random numbers (PRNs) 15, 17, 18 and 23 between 17:00 and 23:00 UT on 07 September 2002.     

基于常规发动机发展STOVL推进系统的总体性能方案

结合F135-PW-600发动机构型,开展基于常规涡扇发动机发展短距起飞/垂直降落(STOVL)推进系统的总体性能方案研究,分析了影响性能方案的各升力部件参数,完成了针对总升力提升的方案优化。研究结果表明:以提高总升力为目标,升力风扇应选取低功耗、小压比、大流量的参数组合;滚转喷管引气量应由风扇裕度、滚转力及其力矩控制需求共同决定;增加外涵道调节机构和重新设计低压涡轮等措施,可将推进系统总升力最高提升近20%;保持主发动机部件不变,通过多学科优化设计,综合考虑质量等结构参数及耗油率等性能参数影响,可使短垂推进系统净收益提升近20%。     

MEMS惯性鞋式行人导航系统

本文以微机械系统（Micro-Electro-Mechanical System,MEMS）惯性器件为测量单元,搭建行人导航硬件系统并进行系统软件设计,硬件系统选用STM32F405作为核心处理器。通过分析行人脚步运动特点,设计零速修正行人导航算法,通过零速修正卡尔曼滤波器单一条件和三条件的零速检测方法进行导航姿态、速度和位置误差评估,并进行鞋式导航实物实验验证。实验结果表明,所设计的鞋式行人导航算法行之有效,并为行人导航系统实际应用指明了研究方向。     

中性气体释放人工产生气辉

电离层中分子性的离子与电子的复合要比氧离子与电子的辐射性复合快得多,因此火箭发动机产生的尾气和空间等离子体主动实验中主动释放的中性气体会对电离层有很大的影响,这么大的电离层扰动现象在过去的实验中经常可以观测到.根据中性气体在热层背景中的扩散方程,考虑电离层F区主要的离子化学反应,研究了H2,H2O和CO2气体在电离层高度上的扩散过程和电离层对所释放气体的响应,计算了气辉的体发射系数和发射强度.结果表明,中性气体在电离层高度上扩散非常迅速,在F区的一些高度上,主要正离子成分由O+转变为其他分子离子,且在释放过程中伴随气辉发射,发射气辉的波长和特征与释放物质的种类有关.      

基于MSP430单片机的固体助推器使用环境监测系统设计

对舰载导弹固体助推器使用环境监测系统的需求进行了分析,给出了基于MSP430F149单片机的监测系统总体方案。对监测系统硬件进行了选择,给出了部分电路连接图和监测系统软件设计。对监测系统样机进行了测试,结果表明该系统可用于固体助推器使用环境监测。     

基于TMS320C32的嵌入式系统的设计与实现

基于TMS320C32中bootload自引导的原理,提出了实现嵌入式系统的上电及复位后程序自动执行功能的一种方法,实验结果证明方法的可行性.