The multi-model assessment of glacio-hydrological regimes can enhance our understanding of glacier response to climate change.This improved knowledge can uplift our computing abilities to estimate the contributing com...The multi-model assessment of glacio-hydrological regimes can enhance our understanding of glacier response to climate change.This improved knowledge can uplift our computing abilities to estimate the contributing components of the river discharge.This study examined and compared the hydrological responses in the glacier-dominated Shigar River basin(SRB)under various climatic scenarios using a semi-distributed Modified Positive Degree Day Model(MPDDM)and a distributed Glacio-hydrological Degree-day Model(GDM).Both glacio-hydrological models were calibrated and validated against the observed hydro-meteorological data from 1988–1992 and 1993–1997.Temperature and precipitation data from Shigar and Skardu meteorological stations were used along with field estimated degree-day factor,temperature,and precipitation gradients.The results from both models indicate that the snow and ice melt are vital contributors to sustain river flow in the catchment.However,MPDDM estimated 68%of rain and baseflow contribution to annual river runoff despite low precipitation during the summer monsoon,while GDM estimated 14%rain and baseflow contribution.Likewise,MPDDM calculated 32%,and GDM generated 86%of the annual river runoff from snow and ice melt.MPDDM simulated river discharge with 0.86 and 0.78 NSE for calibration and validation,respectively.Similarly,GDM simulated river discharge with improved accuracy of 0.87 for calibration and 0.84 NSE for the validation period.The snow and ice melt is significant in sustaining river flow in the SRB,and substantial changes in melt characteristics of snow and ice are expected to have severe consequences on seasonal water availability.Based on the sensitivity analysis,both models’outputs are highly sensitive to the variation in temperature.Furthermore,compared to MPDDM,GDM simulated considerable variation in the river discharge in climate scenarios,RCP4.5 and 8.5,mainly due to the higher sensitivity of GDM model outputs to temperature change.The integration of an updated melt module and two reservoir baseflow module in GDM is anticipated to advance the representation of hydrological components,unlike one reservoir baseflow module used separately in MPDDM.The restructured melt and baseflow modules in GDM have fundamentally enriched our perception of glacio-hydrological dynamics in the catchment.展开更多
The network-on-chip (NoC) architecture is a main factor affecting the system performance of complicated multi-processor systems-on-chips (MPSoCs).To evaluate the effects of the NoC architectures on communication effic...The network-on-chip (NoC) architecture is a main factor affecting the system performance of complicated multi-processor systems-on-chips (MPSoCs).To evaluate the effects of the NoC architectures on communication efficiency,several kinds of techniques have been developed,including various simulators and analytical models.The simulators are accurate but time consuming,especially in large space explorations of diverse network configurations;in contrast,the analytical models are fast and flexible,providing alternative methods for performance evaluation.In this paper,we propose a general analytical model to esti-mate the communication performance for arbitrary NoCs with wormhole routing and virtual channel flow control.To resolve the inherent dependency of successive links occupied by one packet in wormhole routing,we propose the routing path decomposition approach to generating a series of ordered link categories.Then we use the traditional queuing system to derive the fine-grained transmission latency for each network component.According to our experiments,the proposed analytical model provides a good approximation of the average packet latency to the simulation results,and estimates the network throughput precisely under various NoC configurations and workloads.Also,the analytical model runs about 10 5 times faster than the cycle-accurate NoC simulator.Practical applications of the model including bottleneck detection and virtual channel allocation are also presented.展开更多
基金the Himalayan Cryosphere, Climate and Disaster Research Center (HiCCDRC), Kathmandu University for constant support throughout the researchfunded by The Second Tibetan Plateau Scientific Expedition and Research Program (STEP)(Grant No. 2019QZKK0904)+3 种基金supported by the Comprehensive Investigation and Assessment of Natural Hazards in China-Pakistan Economic Corridor (Grant No. 2018FY100500)Ministry of Science and Technology Basic Resources Survey Project (2018FY100506)International Science andTechnology Cooperation Program of China (No. 2018YFE0100100)the National Natural Science Foundation of China (41925030 and 41661144028)
文摘The multi-model assessment of glacio-hydrological regimes can enhance our understanding of glacier response to climate change.This improved knowledge can uplift our computing abilities to estimate the contributing components of the river discharge.This study examined and compared the hydrological responses in the glacier-dominated Shigar River basin(SRB)under various climatic scenarios using a semi-distributed Modified Positive Degree Day Model(MPDDM)and a distributed Glacio-hydrological Degree-day Model(GDM).Both glacio-hydrological models were calibrated and validated against the observed hydro-meteorological data from 1988–1992 and 1993–1997.Temperature and precipitation data from Shigar and Skardu meteorological stations were used along with field estimated degree-day factor,temperature,and precipitation gradients.The results from both models indicate that the snow and ice melt are vital contributors to sustain river flow in the catchment.However,MPDDM estimated 68%of rain and baseflow contribution to annual river runoff despite low precipitation during the summer monsoon,while GDM estimated 14%rain and baseflow contribution.Likewise,MPDDM calculated 32%,and GDM generated 86%of the annual river runoff from snow and ice melt.MPDDM simulated river discharge with 0.86 and 0.78 NSE for calibration and validation,respectively.Similarly,GDM simulated river discharge with improved accuracy of 0.87 for calibration and 0.84 NSE for the validation period.The snow and ice melt is significant in sustaining river flow in the SRB,and substantial changes in melt characteristics of snow and ice are expected to have severe consequences on seasonal water availability.Based on the sensitivity analysis,both models’outputs are highly sensitive to the variation in temperature.Furthermore,compared to MPDDM,GDM simulated considerable variation in the river discharge in climate scenarios,RCP4.5 and 8.5,mainly due to the higher sensitivity of GDM model outputs to temperature change.The integration of an updated melt module and two reservoir baseflow module in GDM is anticipated to advance the representation of hydrological components,unlike one reservoir baseflow module used separately in MPDDM.The restructured melt and baseflow modules in GDM have fundamentally enriched our perception of glacio-hydrological dynamics in the catchment.
基金supported by the National High-Tech Research and Development Program (863) of China (No.2009AA011706)the Fundamental Research Funds for the Central Universities,China
文摘The network-on-chip (NoC) architecture is a main factor affecting the system performance of complicated multi-processor systems-on-chips (MPSoCs).To evaluate the effects of the NoC architectures on communication efficiency,several kinds of techniques have been developed,including various simulators and analytical models.The simulators are accurate but time consuming,especially in large space explorations of diverse network configurations;in contrast,the analytical models are fast and flexible,providing alternative methods for performance evaluation.In this paper,we propose a general analytical model to esti-mate the communication performance for arbitrary NoCs with wormhole routing and virtual channel flow control.To resolve the inherent dependency of successive links occupied by one packet in wormhole routing,we propose the routing path decomposition approach to generating a series of ordered link categories.Then we use the traditional queuing system to derive the fine-grained transmission latency for each network component.According to our experiments,the proposed analytical model provides a good approximation of the average packet latency to the simulation results,and estimates the network throughput precisely under various NoC configurations and workloads.Also,the analytical model runs about 10 5 times faster than the cycle-accurate NoC simulator.Practical applications of the model including bottleneck detection and virtual channel allocation are also presented.
