基于FPGA的液晶控制器研究

现代社会由于信息技术的飞速发展,人类获得的视觉信息很大部分是从各种各样的电子显示器件上获得的,因此,显示技术也有了很大的进步,不仅液晶显示器件本身而且关于液晶驱动控制系统也取得了很大发展.本文介绍了一种基于FPGA的液晶显示控制器的设计,主要论述了使用FPGA设计的用于本系统的特殊SDRAM控制器,以及液晶控制器通过该SDRAM控制器进行显示缓冲器的管理,STN液晶彩色屏灰度显示的时间抖动算法和帧率控制原理及实现,显示数据的缓冲、转化方法,还给出了系统硬件原理图、软件系统的VHDL描述及仿真结果等.     

Temporal evolution analysis of storm-enhanced density during an intense magnetic storm on March 2015

An intense Storm Enhancement Density (SED) event with the magnetic storm occurred on 17–24 March 2015 has been investigated. The morphological character of the SED during different phase of the magnetic storm is examined and compared with the non-storm time. Three intensity indexes, i.e., “general” SED index, “heavy” SED index and “severe” SED index, are defined to represent the intensity of SED respectively represented by the numbers of the ionospheric total electron content (TEC) grids with TEC > 60 TECu, TEC > 80 TECu and TEC > 100 TECu. The temporal evolution of the SED intensity indexes during a time span covering the non-storm time and the magnetic storm time have also been investigated. The SED exhibits a shape with two parallel slender troughs in the middle and low latitudes during the non-storm time and then gradually develops into an ellipse structure as the development of magnetic storm. The intensity of SED and the fluctuation of the TEC evolution are generally corresponding to the fluctuation of Dst index. The analyzing results enrich our understanding of the temporal and spatial evolution of the ionospheric SED.     

Study of TEC changes during geomagnetic storms occurred near the crest of the equatorial ionospheric ionization anomaly in the Indian sector

GPS satellites data obtained at Bhopal (23.16° N, 77.36° E, geomagnetic latitude 14.23° N) India were analyzed to study the TEC changes during several geomagnetic storms (−300 nT < Dst < −50 nT) occurred in 2005–2007. We had segregated the storms according to the Dst value, i.e. moderate storms (−100 nT < Dst ? −50 nT), strong storms (−150 nT < Dst < −100 nT), and severe storms (Dst less than −150 nT). Total of 21 geomagnetic storms (10 moderate, 9 strong, 2 severe) are considered for the present study. Deviation in vertical total electron content (VTEC) during the main phase of the storm was found to be associated with the prompt penetration of electric field originated due to the under-shielding and over-shielding conditions for almost all geomagnetic storms discussed in this paper. For most of the storms VTEC shows the positive percentage deviation during the main phase while it shows positive as well as the negative deviation during the recovery phase of the storms. The −80% deviation in VTEC was found for geomagnetic storm occurred on July 17, 2005 and the negative trend continued for recovery phase of the storm. This was mainly due to the thermospheric composition changes by Joule heating effect at auroral latitudes that generate electric field disturbance at low latitudes. Traveling ionospheric disturbances (TIDs) were responsible for the formation of wave like nature in VTEC for the storms occurred on May 15, 2005, whereas it was not observed for storm occurred on August 24, 2005.     

基于FPGA的液晶控制器研究

现代社会由于信息技术的飞速发展，人类获得的视觉信息很大部分是从各种各样的电子显示器件上获得的，因此，显示技术也有了很大的进步，不仅液晶显示器件本身而且关于液晶驱动控制系统也取得了很大发展。本文介绍了一种基于FPGA的液晶显示控制器的设计，主要论述了使用FPGA设计的用于本系统的特殊SDRAM控制器，以及液晶控制器通过该SDRAM控制器进行显示缓冲器的管理，STN液晶彩色屏灰度显示的时间抖动算法和帧率控制原理及实现，显示数据的缓冲、转化方法，还给出了系统硬件原理图、软件系统的vHDL描述及仿真结果等。