在300～600K温度范围内分析并模拟了栅长为100nm的SOI（Silicon On Insulator）和SOAN（Silicon On Aluminum Nitride）MOSFETs的输出特性和有源区温度分布，得出了SOAN器件更适合高温应用的结论；针对高温应用环境，对SOAN器件结构参...在300～600K温度范围内分析并模拟了栅长为100nm的SOI（Silicon On Insulator）和SOAN（Silicon On Aluminum Nitride）MOSFETs的输出特性和有源区温度分布，得出了SOAN器件更适合高温应用的结论；针对高温应用环境，对SOAN器件结构参数及工艺参数进行优化，得出了各个参数的优化值，并使用优化后参数仿真CMOS反相器的瞬态特性，结果显示在环境温度为300K和500K时，SOANCMOS门极延迟分别为19ps、25．5ps；而SOI CMOS的门极延迟在相同的温度下分别为28．5ps、35．5ps。展开更多
Since the early Pleistocene,climatic variability has profoundly influenced population dynamics,including the migration of hominins into and out of Africa.In South Asia,Quaternary sediments,particularly those found in ...Since the early Pleistocene,climatic variability has profoundly influenced population dynamics,including the migration of hominins into and out of Africa.In South Asia,Quaternary sediments,particularly those found in the Siwaliks,provide a valuable record of climatic changes relevant to hominin habitation.While the upper Soan Valley in Pakistan has been extensively studied for evidence of hominin to modern human activities,the associated environmental and climatic changes remain underexplored.This study aims to elucidate the climatic evolution of the Quaternary sediments in the Riwat area,with the primary objective of reconstructing the environmental conditions that facilitated long-term hominin settlement and survival.To address this knowledge gap,we analyzed the geochemistry and clay mineralogy of 46 sediment samples utilizing spectroscopy and X-ray diffractometry(XRD),focusing on the Plio-Quaternary period.Our findings reveal three distinct climatic stages.The first stage(StageⅠ),was characterized by cold conditions during the Pliocene,and was further divided into semi-arid to semi-humid substages based on C-values.This was followed by a cold to humid climatic stage(StageⅡ)during the early to middle Pleistocene,marked by moderate to high chemical weathering,which was also categorized into semi-arid to semi-humid substages.Within StageⅡ,a warm and humid phase was inferred during the early to middle Pleistocene,culminating in the coldest and most arid conditions of StageⅢduring the late Pleistocene to Holocene.The climatic changes observed are indicative of the uplift of the Himalayan-Tibetan Plateau and the influence of the southwestern monsoon on the Indian subcontinent.Moderate to intense monsoonal activity characterized the early to middle Pleistocene,creating conditions conducive to early hominin settlement and adaptation due to the availability of resources.Conversely,environmental conditions during periods of weakened monsoons exhibited an arid climate from the late Pleistocene to Holocene(corresponding to MIS 1-4 in oceanic records).This study enhances our understanding of hominin-climate interactions and has implications for the role of climate in shaping diverse hominin habitation patterns,both globally(out of Africa)and regionally(South Asian)contexts.展开更多
The Soil and Water Assessment Tool （SWAT） was implemented in a small forested watershed of the Soan River Basin innorthern Pakistan through application of the sequential uncertainty fitting （SUFI-2） method to inve...The Soil and Water Assessment Tool （SWAT） was implemented in a small forested watershed of the Soan River Basin innorthern Pakistan through application of the sequential uncertainty fitting （SUFI-2） method to investigate the associateduncertainty in runoff and sediment load estimation. The model was calibrated for a 10-year period （1991–2000） with aninitial 4-year warm-up period （1987–1990）, and was validated for the subsequent 10-year period （2001–2010）. Themodel evaluation indices R2 （the coefficient of determination）, NS （the Nash-Sutcliffe efficiency）, and PBIAS （percentbias） for stream flows simulation indicated that there was a good agreement between the measured and simulated flows.To assess the uncertainty in the model outputs, p-factor （a 95% prediction uncertainty, 95PPU） and r-factors （averagewideness width of the 95PPU band divided by the standard deviation of the observed values） were taken into account.The 95PPU band bracketed 72% of the observed data during the calibration and 67% during the validation. The r-factorwas 0.81 during the calibration and 0.68 during the validation. For monthly sediment yield, the model evaluation coefficients（R2 and NS） for the calibration were computed as 0.81 and 0.79, respectively; for validation, they were 0.78and 0.74, respectively. Meanwhile, the 95PPU covered more than 60% of the observed sediment data during calibrationand validation. Moreover, improved model prediction and parameter estimation were observed with the increasednumber of iterations. However, the model performance became worse after the fourth iterations due to an unreasonableparameter estimation. Overall results indicated the applicability of the SWAT model with moderate levels of uncertaintyduring the calibration and high levels during the validation. Thus, this calibrated SWAT model can be used for assessmentof water balance components, climate change studies, and land use management practices.展开更多
Land use changes such as deforestation,increase in cropping or grazing areas and built-up land, likely modify the water balance and land surface behavior in the Himalayan watersheds.An integrated approach of hydrologi...Land use changes such as deforestation,increase in cropping or grazing areas and built-up land, likely modify the water balance and land surface behavior in the Himalayan watersheds.An integrated approach of hydrological and hydraulic modeling was adopted for comparative analysis of hydrological pattern in three Himalayan watersheds i.e.Khanpur,Rawal and Simly situated in the Northern territory of Pakistan.The rainfall-runoff model SWAT- Soil and water assessment tool and Hydro CAD were calibrated for the selected watersheds.The correlation analysis of the precipitation data of two climate stations i.e.Murree and Islamabad, with the discharge data of three rivers was utilized to select best suitable input precipitation data for Hydro CAD rainfall-runoff modeling.The peak flood hydrograph were generated using Hydro CAD runoff to optimize the basin parameters like CN, runoff volume, peak flows of the three watersheds.The hydrological response of the Rawal watershed was studied as a case study to different scenarios of land use change using SWAT model.The scenario of high deforestation indicated a decline of about 6.3% in the groundwater recharge tostream while increase of 7.1% in the surface runoff has been observed under the scenario of growth in urbanization in the recent decades.The integrated modeling approach proved helpful in investigating the hydrological behavior under changing environment at watershed level in the Himalayan region.展开更多
Compared with bulk-silicon technology, silicon-on-insulator (SOI) technology possesses many advan-tages but it is inevitable that the buried silicon dioxide layer also thermally insulates the metal – oxide – silicon...Compared with bulk-silicon technology, silicon-on-insulator (SOI) technology possesses many advan-tages but it is inevitable that the buried silicon dioxide layer also thermally insulates the metal – oxide – silicon field-effect transistors (MOSFETs) from the bulk due to the low thermal conductivity. One of the alternative insulator to replace the buried oxide layer is aluminum nitride (AlN), which has a thermal conductivity that is about 200 times higher than that of SiO2 (320 W·m ? 1·K? 1 versus 1.4 W·m? 1·K? 1). To investigate the self-heating effects of small-size MOSFETs fabricated on silicon-on-aluminum nitride (SOAN) substrate, a two-dimensional numerical analysis is performed by using a device simulator called MEDICI run on a Solaris workstation to simulate the electri-cal characteristics and temperature distribution by comparing with those of bulk and standard SOI MOSFETs. Our study suggests that AlN is a suitable alternative to silicon dioxide as a buried dielectric in SOI and expands the appli-cations of SOI to high temperature conditions.展开更多
文摘在300～600K温度范围内分析并模拟了栅长为100nm的SOI（Silicon On Insulator）和SOAN（Silicon On Aluminum Nitride）MOSFETs的输出特性和有源区温度分布，得出了SOAN器件更适合高温应用的结论；针对高温应用环境，对SOAN器件结构参数及工艺参数进行优化，得出了各个参数的优化值，并使用优化后参数仿真CMOS反相器的瞬态特性，结果显示在环境温度为300K和500K时，SOANCMOS门极延迟分别为19ps、25．5ps；而SOI CMOS的门极延迟在相同的温度下分别为28．5ps、35．5ps。
基金China scholarship council for continuous support in this research projectsupported by the National Natural Science Foundation of China(NSFC-42330411)
文摘Since the early Pleistocene,climatic variability has profoundly influenced population dynamics,including the migration of hominins into and out of Africa.In South Asia,Quaternary sediments,particularly those found in the Siwaliks,provide a valuable record of climatic changes relevant to hominin habitation.While the upper Soan Valley in Pakistan has been extensively studied for evidence of hominin to modern human activities,the associated environmental and climatic changes remain underexplored.This study aims to elucidate the climatic evolution of the Quaternary sediments in the Riwat area,with the primary objective of reconstructing the environmental conditions that facilitated long-term hominin settlement and survival.To address this knowledge gap,we analyzed the geochemistry and clay mineralogy of 46 sediment samples utilizing spectroscopy and X-ray diffractometry(XRD),focusing on the Plio-Quaternary period.Our findings reveal three distinct climatic stages.The first stage(StageⅠ),was characterized by cold conditions during the Pliocene,and was further divided into semi-arid to semi-humid substages based on C-values.This was followed by a cold to humid climatic stage(StageⅡ)during the early to middle Pleistocene,marked by moderate to high chemical weathering,which was also categorized into semi-arid to semi-humid substages.Within StageⅡ,a warm and humid phase was inferred during the early to middle Pleistocene,culminating in the coldest and most arid conditions of StageⅢduring the late Pleistocene to Holocene.The climatic changes observed are indicative of the uplift of the Himalayan-Tibetan Plateau and the influence of the southwestern monsoon on the Indian subcontinent.Moderate to intense monsoonal activity characterized the early to middle Pleistocene,creating conditions conducive to early hominin settlement and adaptation due to the availability of resources.Conversely,environmental conditions during periods of weakened monsoons exhibited an arid climate from the late Pleistocene to Holocene(corresponding to MIS 1-4 in oceanic records).This study enhances our understanding of hominin-climate interactions and has implications for the role of climate in shaping diverse hominin habitation patterns,both globally(out of Africa)and regionally(South Asian)contexts.
基金supported by the Centre of Excellence in Water Resources Engineering, University of Engineering and Technology Lahore, and local authorities in Pakistan
文摘The Soil and Water Assessment Tool （SWAT） was implemented in a small forested watershed of the Soan River Basin innorthern Pakistan through application of the sequential uncertainty fitting （SUFI-2） method to investigate the associateduncertainty in runoff and sediment load estimation. The model was calibrated for a 10-year period （1991–2000） with aninitial 4-year warm-up period （1987–1990）, and was validated for the subsequent 10-year period （2001–2010）. Themodel evaluation indices R2 （the coefficient of determination）, NS （the Nash-Sutcliffe efficiency）, and PBIAS （percentbias） for stream flows simulation indicated that there was a good agreement between the measured and simulated flows.To assess the uncertainty in the model outputs, p-factor （a 95% prediction uncertainty, 95PPU） and r-factors （averagewideness width of the 95PPU band divided by the standard deviation of the observed values） were taken into account.The 95PPU band bracketed 72% of the observed data during the calibration and 67% during the validation. The r-factorwas 0.81 during the calibration and 0.68 during the validation. For monthly sediment yield, the model evaluation coefficients（R2 and NS） for the calibration were computed as 0.81 and 0.79, respectively; for validation, they were 0.78and 0.74, respectively. Meanwhile, the 95PPU covered more than 60% of the observed sediment data during calibrationand validation. Moreover, improved model prediction and parameter estimation were observed with the increasednumber of iterations. However, the model performance became worse after the fourth iterations due to an unreasonableparameter estimation. Overall results indicated the applicability of the SWAT model with moderate levels of uncertaintyduring the calibration and high levels during the validation. Thus, this calibrated SWAT model can be used for assessmentof water balance components, climate change studies, and land use management practices.
文摘Land use changes such as deforestation,increase in cropping or grazing areas and built-up land, likely modify the water balance and land surface behavior in the Himalayan watersheds.An integrated approach of hydrological and hydraulic modeling was adopted for comparative analysis of hydrological pattern in three Himalayan watersheds i.e.Khanpur,Rawal and Simly situated in the Northern territory of Pakistan.The rainfall-runoff model SWAT- Soil and water assessment tool and Hydro CAD were calibrated for the selected watersheds.The correlation analysis of the precipitation data of two climate stations i.e.Murree and Islamabad, with the discharge data of three rivers was utilized to select best suitable input precipitation data for Hydro CAD rainfall-runoff modeling.The peak flood hydrograph were generated using Hydro CAD runoff to optimize the basin parameters like CN, runoff volume, peak flows of the three watersheds.The hydrological response of the Rawal watershed was studied as a case study to different scenarios of land use change using SWAT model.The scenario of high deforestation indicated a decline of about 6.3% in the groundwater recharge tostream while increase of 7.1% in the surface runoff has been observed under the scenario of growth in urbanization in the recent decades.The integrated modeling approach proved helpful in investigating the hydrological behavior under changing environment at watershed level in the Himalayan region.
基金Supported by the Special Funds for Major State Basic Research Projects (No.G2000036506)the National Natural Science Foundation of China (No. 60476006)
文摘Compared with bulk-silicon technology, silicon-on-insulator (SOI) technology possesses many advan-tages but it is inevitable that the buried silicon dioxide layer also thermally insulates the metal – oxide – silicon field-effect transistors (MOSFETs) from the bulk due to the low thermal conductivity. One of the alternative insulator to replace the buried oxide layer is aluminum nitride (AlN), which has a thermal conductivity that is about 200 times higher than that of SiO2 (320 W·m ? 1·K? 1 versus 1.4 W·m? 1·K? 1). To investigate the self-heating effects of small-size MOSFETs fabricated on silicon-on-aluminum nitride (SOAN) substrate, a two-dimensional numerical analysis is performed by using a device simulator called MEDICI run on a Solaris workstation to simulate the electri-cal characteristics and temperature distribution by comparing with those of bulk and standard SOI MOSFETs. Our study suggests that AlN is a suitable alternative to silicon dioxide as a buried dielectric in SOI and expands the appli-cations of SOI to high temperature conditions.
