The River Chenab is one of the main western rivers of the Indus River system in Pakistan, which undergoes intensive inundation almost every year during the late monsoon period. The present study performs flood frequen...The River Chenab is one of the main western rivers of the Indus River system in Pakistan, which undergoes intensive inundation almost every year during the late monsoon period. The present study performs flood frequency analyses for the river basin as well as simulates different levels of water flow in the system to speculate all kinds of inundation under different scenarios, i.e., to predict flood hazard and flood extended areas. Flood frequency analyses were performed at MARALA Headworks to Khanki Headworks. Data were collected from the Punjab Irrigation Department, Pakistan and from USGS and ASTER GDEM. The peak discharge of MARALA Headworks had been analyzed for 25 years. The preprocessing was performed in HEC Geo-RAS after preprocessing model run in HEC-RAS. After analysis the data were exported in HEC-RAS to ARCMAP to generate a floodplain and inundation map. Our analysis generated the result that different areas would be under water in different return periods. Flood hazards maps for different return periods 10, 20, 50 and 100 years were conducted using annual peaks flow of 35 years from 1980 to 2016. The maximum discharges at up and down stream for different periods were obtained using Gumbel distribution model results which showed that different areas were predicted under water in different return periods and affected areas after five years’ return period.展开更多
The primary technique used for air traffic surveillance is radar.However,nowadays,its role in surveillance is gradually being replaced by the recently adopted Automatic Dependent Surveillance-Broadcast(ADS-B).ADS-B of...The primary technique used for air traffic surveillance is radar.However,nowadays,its role in surveillance is gradually being replaced by the recently adopted Automatic Dependent Surveillance-Broadcast(ADS-B).ADS-B offers a higher accuracy,lower power consumption,and longer range than radar,thus providing more safety to aircraft.The coverage of terrestrial radar and ADS-B is confined to continental parts of the globe,leaving oceans and poles uncovered by real-time surveillance measures.This study presents an optimized Low-Earth Orbit(LEO)-based ADS-B constellation for global air traffic surveillance over intercontinental trans-oceanic flight routes.The optimization algorithm is based on performance evaluation parameters,i.e.,coverage time,satellite availability,and orbit stability(precession and perigee rotation),and communication analysis.The results indicate that the constellation provides ample coverage in the simulated global oceanic regions.The constellation is a feasible and cost-effective solution for global air supervision,which can supplement terrestrial ADS-B and radar systems.展开更多
文摘The River Chenab is one of the main western rivers of the Indus River system in Pakistan, which undergoes intensive inundation almost every year during the late monsoon period. The present study performs flood frequency analyses for the river basin as well as simulates different levels of water flow in the system to speculate all kinds of inundation under different scenarios, i.e., to predict flood hazard and flood extended areas. Flood frequency analyses were performed at MARALA Headworks to Khanki Headworks. Data were collected from the Punjab Irrigation Department, Pakistan and from USGS and ASTER GDEM. The peak discharge of MARALA Headworks had been analyzed for 25 years. The preprocessing was performed in HEC Geo-RAS after preprocessing model run in HEC-RAS. After analysis the data were exported in HEC-RAS to ARCMAP to generate a floodplain and inundation map. Our analysis generated the result that different areas would be under water in different return periods. Flood hazards maps for different return periods 10, 20, 50 and 100 years were conducted using annual peaks flow of 35 years from 1980 to 2016. The maximum discharges at up and down stream for different periods were obtained using Gumbel distribution model results which showed that different areas were predicted under water in different return periods and affected areas after five years’ return period.
文摘The primary technique used for air traffic surveillance is radar.However,nowadays,its role in surveillance is gradually being replaced by the recently adopted Automatic Dependent Surveillance-Broadcast(ADS-B).ADS-B offers a higher accuracy,lower power consumption,and longer range than radar,thus providing more safety to aircraft.The coverage of terrestrial radar and ADS-B is confined to continental parts of the globe,leaving oceans and poles uncovered by real-time surveillance measures.This study presents an optimized Low-Earth Orbit(LEO)-based ADS-B constellation for global air traffic surveillance over intercontinental trans-oceanic flight routes.The optimization algorithm is based on performance evaluation parameters,i.e.,coverage time,satellite availability,and orbit stability(precession and perigee rotation),and communication analysis.The results indicate that the constellation provides ample coverage in the simulated global oceanic regions.The constellation is a feasible and cost-effective solution for global air supervision,which can supplement terrestrial ADS-B and radar systems.
