Since 2011,America has maintained its position as the world’s largest natural gas producer.Since 2017,America has consistently experienced a surplus in natural gas supply,becoming a net exporter of natural gas.Americ...Since 2011,America has maintained its position as the world’s largest natural gas producer.Since 2017,America has consistently experienced a surplus in natural gas supply,becoming a net exporter of natural gas.America’s“natural gas independence”has reshaped the global natural gas market,creating a new pattern of“supply shifting westward and consumption shifting eastward”.展开更多
Upstream-downstream relationships of annual streamflow discharges and severity and frequency of stream-flow drought events are critical in understanding how streamflow droughts propagate over time and space. Such info...Upstream-downstream relationships of annual streamflow discharges and severity and frequency of stream-flow drought events are critical in understanding how streamflow droughts propagate over time and space. Such information can be used to resolve water disputes, trigger mitigation strategies, and understand how streamflow changes due to changes in the environment. During drought years, such information is even more critical as water resources are contested. The objective of this research is to study the upstream-downstream relationships of streamflow in Nebraska along four major river systems with diverse hydrologic characteris-tics and human activities: North Platte, Big Blue, Republican, and Niobrara. The relationships among the upstream and downstream stations along the four rivers are investigated by comparing several statistics de-rived from the annual flow discharge and on drought events. Trend analysis and coefficient of variation are applied to annual flow discharge values, and a host of drought-related parameters (e.g., annual maximum drought duration, annual accumulated drought duration, number of drought events) are also computed with respect to five different levels of streamflow drought events: water shortage, mild drought, moderate drought, significant drought, and extreme drought. The paired-t test and ANOVA with MIXED procedure are subse-quently applied to the statistics to observe whether there is a significant difference between upstream and downstream stations along a river. The analysis allows us to characterize the upstream-downstream relation-ships of the four river systems, laying the groundwork for further investigations to identify the reasons for some of the trends and observations. These findings will be essential in water resources management during or prior to hydrological droughts.展开更多
We investigate a wavelength-division-multiplexing passive optical network(WDM-PON) with centralized lightwave and direct detection. The system is demonstrated for symmetric 10 Gbit/s differential phase-shift keying(DP...We investigate a wavelength-division-multiplexing passive optical network(WDM-PON) with centralized lightwave and direct detection. The system is demonstrated for symmetric 10 Gbit/s differential phase-shift keying(DPSK) downstream signals and on-off keying(OOK) upstream signals,respectively. A wavelength reused scheme is employed to carry the upstream data by using a reflective semiconductor optical amplifier(RSOA) as an intensity modulator at the optical network unit(ONU). The constant-intensity property of the DPSK modulation format can keep high extinction ratio(ER) of downstream signal and reduce the crosstalk to the upstream signal. The bit error rate(BER) performance of our scheme shows that the proposed 10 Gbit/s symmetric WDM-PON can achieve error free transmission over 25-km-long fiber transmission with low power penalty.展开更多
A case study is introduced and discussed concerning water dispute of misuse and pollution between up\| and down\|stream parts. The relations between water usage and local industrial structures are analyzed. Results sh...A case study is introduced and discussed concerning water dispute of misuse and pollution between up\| and down\|stream parts. The relations between water usage and local industrial structures are analyzed. Results show it is important to change industrial structures of the target region along with controlling water pollution by technical and engineering methods. Three manners of upstream-downstream cooperation are presented and discussed based on the actual conditions of Guangting Reservoir watershed. Two typical scenarios are supposed and studied along with the local plan on water resources development. The best solution for this cooperation presents a good way to help the upstream developing in a new pattern of eco-economy.展开更多
River Tano, located in the Brong Ahafo region of Ghana, has a number of socio-ecological functions. Anthropogenic activities such as farming, washing, and discharge of industrial effluents into the river pose serious ...River Tano, located in the Brong Ahafo region of Ghana, has a number of socio-ecological functions. Anthropogenic activities such as farming, washing, and discharge of industrial effluents into the river pose serious threat to human health. In view of this, water quality campaign was carried out for a period of 12 months by taking samples from the source and the downstream end of the river and analysing for some physico-chemical parameters. The results showed that most of the physico-chemical parameters such as pH, fluoride, nitrite, manganese and temperature were not within the regulatory safe limit. Although the levels of total alkalinity, total iron, ammonia and phosphate kept fluctuating along the course of the river, the difference were not statistically significant apart from fluoride and phosphate which showed significant difference between the upstream and downstream levels. This may be attributed to anthropogenic activities such as farming and washing in the river which implies that human activities have impacted slightly on the water quality. It is recommended that the relevant stakeholders should come together to enforce the environmental laws regarding protection of water bodies and do continuous monitoring for early detection of any change in quality of the River Tano.展开更多
Panicle architecture is an agronomic determinant of crop yield and a target for cereal crop improvement.To investigate its molecular mechanisms in rice,we performed map-based cloning and characterization of OPEN PANIC...Panicle architecture is an agronomic determinant of crop yield and a target for cereal crop improvement.To investigate its molecular mechanisms in rice,we performed map-based cloning and characterization of OPEN PANICLE 1(OP1),a gain-of-function allele of LIGULELESS 1(LG1),controlling the spread-panicle phenotype.This allele results from a 48-bp deletion in the LG1 upstream region and promotes pulvinus development at the base of the primary branch.Increased OP1 expression and altered panicle phenotype in chimeric transgenic plants and upstream-region knockout mutants indicated that the deletion regulates spread-panicle architecture in the mutant spread panicle 1(sp1).Knocking out BRASSINOSTEROID UPREGULATED1(BU1)gene in the background of OP1 complementary plants resulted in compact panicles,suggesting OP1 may regulate inflorescence architecture via the brassinosteroid signaling pathway.We regard that manipulating the upstream regulatory region of OP1 or genes involved in BR signal pathway could be an efficient way to improve rice inflorescence architecture.展开更多
To numerically study the impact of total temperature distortion on a transonic compressor with reduced computational costs,a Body-Force Model(BFM)is developed.Firstly,the interactions between the distorted flow and th...To numerically study the impact of total temperature distortion on a transonic compressor with reduced computational costs,a Body-Force Model(BFM)is developed.Firstly,the interactions between the distorted flow and the compressor are analyzed using full-annulus Unsteady Reynolds-Averaged Navier-Stokes(URANS)results and the orbit method.It is found that the induced swirl distortion and the mass flux nonuniformity are intensified in the compressor upstream flow field.A correction factor is thus added to the BFM to account for the effect of the induced swirl,which is crucial for the accurate representation of distortion transfer in the intake.Then,steady simulations with large-amplitude 180circumferential total temperature distortion are performed using the developed BFM.It is shown that the distorted compressor map simulated with the BFM matches well with URANS results.The circumferential phase shift of total temperature and the generation of the additional total pressure distortion across the rotor are in line with the time-averaged URANS flow field.The compressor upstream effects on the distorted inflow can also be exactly captured.All above-mentioned results demonstrate the BFM developed in this paper can effectively capture the distorted flow features inside the compressor,and significantly reduce the computational costs by five orders of magnitude compared with URANS.展开更多
Grew up in this paper, in view of the urban rail transit ramp section, from the viewpoint of energy saving and increase contact line voltage index, the paper puts forward a kind appropriate location in the traction po...Grew up in this paper, in view of the urban rail transit ramp section, from the viewpoint of energy saving and increase contact line voltage index, the paper puts forward a kind appropriate location in the traction power supply division set up, the concrete implementation plan of the downlink power supply in parallel. At the same time, it puts forward a corresponding bilateral jump does not affect both the dc traction power supply system protection function, safe and reliable to achieve multichannel parallel protection scheme and the running safety and energy saving effect was analyzed.展开更多
Peninsular Malaysia is already well known for having rare earth(RE)resources.However,pertinent data and information on upstream RE resources and reserve potential in Malaysia are yet to be established.It is vital to i...Peninsular Malaysia is already well known for having rare earth(RE)resources.However,pertinent data and information on upstream RE resources and reserve potential in Malaysia are yet to be established.It is vital to identify opportunities and challenges for value addition to rare earth elements(REEs)deposits in Malaysia.Therefore,this study evaluates the potential of Malaysian geological formations to serve as repositories for RE resources,such as rare earth minerals(REMs)and REEs,by elucidating the geological processes that are considered critical to the formation of the various deposit types.This paper concisely reviews possible REE mineralization in alkaline igneous rocks,pegmatites,placer deposits:monazite and xenotime,marine sediments,river and lake sediments,ion adsorption clays(IAC)deposits,and shale/coal deposits found in Malaysia.Comparisons between Malaysian deposits revealed that these deposits are potentially enriched with RE resources showing geological formations across the world.The paper reviews the methods and flowsheets used for the recovery of REMs and REEs from primary,secondary as well as alternative resources,with special consideration to the hydrometallurgical procedures comprising of leaching with acids and alkalis tailed by ion exchange,solvent extraction,or precipitation.The REEs ecosystem of Malaysia has also been discussed by considering the latest information from the Malaysian Investment Development Authority(MIDA),the REEs processing center,the Academy of Science of Malaysia(ASM),the People’s Republic of China(PRC),Lynas Malaysia Sdn.Bhd.(Lynas),Ministry of Energy and Natural Resources(NRECC),Jabatan Mineral&Geosains(JMG),Ministry of Science,Technology,and Innovation(MOSTI),and the Malaysian Chamber of Mines.The information on upstream RE resources and recent hydrometallurgical approaches provided in this study will contribute to developing and enhancing midstream and downstream RE-based manufacturing and processing operations in Malaysia.展开更多
Little is known about the mechanism of climate-vegetation coverage coupled changes in the Tibetan Plateau(TP)region,which is the most climatically sensitive and ecologically fragile region with the highest terrain in ...Little is known about the mechanism of climate-vegetation coverage coupled changes in the Tibetan Plateau(TP)region,which is the most climatically sensitive and ecologically fragile region with the highest terrain in the world.This study,using multisource datasets(including satellite data and meteorological observations and reanalysis data)revealed the mutual feedback mechanisms between changes in climate(temperature and precipitation)and vegetation coverage in recent decades in the Hengduan Mountains Area(HMA)of the southeastern TP and their influences on climate in the downstream region,the Sichuan Basin(SCB).There is mutual facilitation between rising air temperature and increasing vegetation coverage in the HMA,which is most significant during winter,and then during spring,but insignificant during summer and autumn.Rising temperature significantly enhances local vegetation coverage,and vegetation greening in turn heats the atmosphere via enhancing net heat flux from the surface to the atmosphere.The atmospheric heating anomaly over the HMA thickens the atmospheric column and increases upper air pressure.The high pressure anomaly disperses downstream via the westerly flow,expands across the SCB,and eventually increases the SCB temperature.This effect lasts from winter to the following spring,which may cause the maximum increasing trend of the SCB temperature and vegetation coverage in spring.These results are helpful for estimating future trends in climate and eco-environmental variations in the HMA and SCB under warming scenarios,as well as seasonal forecasting based on the connection between the HMA eco-environment and SCB climate.展开更多
Glaciers in the Yarlung Zangbo Downstream Basin(YZDB)are sensitive to global climate change.The equilibrium-line altitude(ELA)is a key indicator of glacial development.Current models for simulating the meteorological ...Glaciers in the Yarlung Zangbo Downstream Basin(YZDB)are sensitive to global climate change.The equilibrium-line altitude(ELA)is a key indicator of glacial development.Current models for simulating the meteorological ELA underestimate the extent of glacial advance during the Last Glacial Maximum(LGM)in the YZDB and cannot explain the large-scale glacial extension compared with the Yarlung Zangbo Midstream Basin(YZMB).In this study,the distribution of ELA in the LGM is reconstructed using high-resolution 80-km ECHAM5 simulations and empirical relationships between temperature and precipitation.Changes in ELA between the LGM and pre-industrial era(PI)are compared.Our simulated ELA closely fits the published field data.In the YZDB,simulated LGM ELAs range from ca.3500 m to over 4900 m,representing declines of ca.300–950 m.The ECHAM5 simulations better reflect the complex topographic features than most coarse-resolution climate models,and the ELA distribution is controlled by the spatial arrangement of river valley systems and mountain ranges and their impact on precipitation.Compared with the PI era,most of the monsoon precipitation in the LGM was concentrated in the YZDB,which is the main driver of glacial extension and the differential response of the downstream and midstream basins.展开更多
Using over eight years of Mars Atmosphere and Volatile Evolutio N(MAVEN)data,from November 2014 to May 2023,we have investigated the Martian nightside ionospheric magnetic field distribution under the influence of ups...Using over eight years of Mars Atmosphere and Volatile Evolutio N(MAVEN)data,from November 2014 to May 2023,we have investigated the Martian nightside ionospheric magnetic field distribution under the influence of upstream solar wind drivers,including the interplanetary magnetic field intensity(∣BIMF∣),solar wind dynamic pressure(PS W),solar extreme ultraviolet flux(EUV),and Martian seasons(L s).Our analysis reveals pronounced correlations between magnetic field residuals and both∣BIMF∣and PS W.Correlations observed with EUV flux and Ls were weaker—notably,magnetic field residuals increased during periods of high EUV flux and at Mars perihelion.We find that the IMF penetrates to an altitude of 200 km under a wide range of upstream conditions,penetrating notably deeper under high∣BIMF∣andPSWconditions.Our analysis also indicates that EUV flux and IMF cone angle have minimal impact on IMF penetration depth.Those findings provide useful constraints on the dynamic nature of Martian atmospheric escape processes and their evolution,suggesting that historical solar wind conditions may have facilitated deeper IMF penetration and higher rates of ionospheric escape than are observed now.Moreover,by establishing criteria for magnetic‘quiet’conditions,this study offers new insights into the planet’s magnetic environment under varying solar wind influences,knowledge that should help refine models of the Martian crustal magnetic field.展开更多
In the context of emerging engineering disciplines,a hybrid teaching reform for the Bioengineering Downstream Technology course,based on ideological and political education and online open courses,is being carried out...In the context of emerging engineering disciplines,a hybrid teaching reform for the Bioengineering Downstream Technology course,based on ideological and political education and online open courses,is being carried out.This reform focuses on aspects such as“building a professional teacher team for ideological and political education,scientifically designing the ideological and political teaching system,innovating classroom teaching methods,and improving both formative and summative evaluation systems.”The“Craftsmanship in Education and Cultivating Soul and Roots”small private online course hybrid teaching reform for the Bioengineering Downstream Technology online open course provides a replicable model for the comprehensive implementation of ideological and political education in engineering courses and offers a reference for advancing ideological and political education and hybrid teaching reform in new engineering disciplines.展开更多
文摘Since 2011,America has maintained its position as the world’s largest natural gas producer.Since 2017,America has consistently experienced a surplus in natural gas supply,becoming a net exporter of natural gas.America’s“natural gas independence”has reshaped the global natural gas market,creating a new pattern of“supply shifting westward and consumption shifting eastward”.
文摘Upstream-downstream relationships of annual streamflow discharges and severity and frequency of stream-flow drought events are critical in understanding how streamflow droughts propagate over time and space. Such information can be used to resolve water disputes, trigger mitigation strategies, and understand how streamflow changes due to changes in the environment. During drought years, such information is even more critical as water resources are contested. The objective of this research is to study the upstream-downstream relationships of streamflow in Nebraska along four major river systems with diverse hydrologic characteris-tics and human activities: North Platte, Big Blue, Republican, and Niobrara. The relationships among the upstream and downstream stations along the four rivers are investigated by comparing several statistics de-rived from the annual flow discharge and on drought events. Trend analysis and coefficient of variation are applied to annual flow discharge values, and a host of drought-related parameters (e.g., annual maximum drought duration, annual accumulated drought duration, number of drought events) are also computed with respect to five different levels of streamflow drought events: water shortage, mild drought, moderate drought, significant drought, and extreme drought. The paired-t test and ANOVA with MIXED procedure are subse-quently applied to the statistics to observe whether there is a significant difference between upstream and downstream stations along a river. The analysis allows us to characterize the upstream-downstream relation-ships of the four river systems, laying the groundwork for further investigations to identify the reasons for some of the trends and observations. These findings will be essential in water resources management during or prior to hydrological droughts.
基金the Alexander von Humboldt Foundation for their support
文摘We investigate a wavelength-division-multiplexing passive optical network(WDM-PON) with centralized lightwave and direct detection. The system is demonstrated for symmetric 10 Gbit/s differential phase-shift keying(DPSK) downstream signals and on-off keying(OOK) upstream signals,respectively. A wavelength reused scheme is employed to carry the upstream data by using a reflective semiconductor optical amplifier(RSOA) as an intensity modulator at the optical network unit(ONU). The constant-intensity property of the DPSK modulation format can keep high extinction ratio(ER) of downstream signal and reduce the crosstalk to the upstream signal. The bit error rate(BER) performance of our scheme shows that the proposed 10 Gbit/s symmetric WDM-PON can achieve error free transmission over 25-km-long fiber transmission with low power penalty.
文摘A case study is introduced and discussed concerning water dispute of misuse and pollution between up\| and down\|stream parts. The relations between water usage and local industrial structures are analyzed. Results show it is important to change industrial structures of the target region along with controlling water pollution by technical and engineering methods. Three manners of upstream-downstream cooperation are presented and discussed based on the actual conditions of Guangting Reservoir watershed. Two typical scenarios are supposed and studied along with the local plan on water resources development. The best solution for this cooperation presents a good way to help the upstream developing in a new pattern of eco-economy.
文摘River Tano, located in the Brong Ahafo region of Ghana, has a number of socio-ecological functions. Anthropogenic activities such as farming, washing, and discharge of industrial effluents into the river pose serious threat to human health. In view of this, water quality campaign was carried out for a period of 12 months by taking samples from the source and the downstream end of the river and analysing for some physico-chemical parameters. The results showed that most of the physico-chemical parameters such as pH, fluoride, nitrite, manganese and temperature were not within the regulatory safe limit. Although the levels of total alkalinity, total iron, ammonia and phosphate kept fluctuating along the course of the river, the difference were not statistically significant apart from fluoride and phosphate which showed significant difference between the upstream and downstream levels. This may be attributed to anthropogenic activities such as farming and washing in the river which implies that human activities have impacted slightly on the water quality. It is recommended that the relevant stakeholders should come together to enforce the environmental laws regarding protection of water bodies and do continuous monitoring for early detection of any change in quality of the River Tano.
基金supported by the National Natural Science Foundation of China(31925029,31471457)the National Key Research and Development Project of China(2021YFD120010105)Guangdong Key Laboratory of New Technology in Rice Breeding(2020B1212060047)。
文摘Panicle architecture is an agronomic determinant of crop yield and a target for cereal crop improvement.To investigate its molecular mechanisms in rice,we performed map-based cloning and characterization of OPEN PANICLE 1(OP1),a gain-of-function allele of LIGULELESS 1(LG1),controlling the spread-panicle phenotype.This allele results from a 48-bp deletion in the LG1 upstream region and promotes pulvinus development at the base of the primary branch.Increased OP1 expression and altered panicle phenotype in chimeric transgenic plants and upstream-region knockout mutants indicated that the deletion regulates spread-panicle architecture in the mutant spread panicle 1(sp1).Knocking out BRASSINOSTEROID UPREGULATED1(BU1)gene in the background of OP1 complementary plants resulted in compact panicles,suggesting OP1 may regulate inflorescence architecture via the brassinosteroid signaling pathway.We regard that manipulating the upstream regulatory region of OP1 or genes involved in BR signal pathway could be an efficient way to improve rice inflorescence architecture.
基金the National Science and Technology Major Project,China(Nos.J2019-Ⅱ-0020-0041 and J2019-Ⅱ-0017-0038)the Science Center for Gas Turbine Project,China(No.P2022-A-Ⅱ-002-001)the National Natural Science Foundation of China(No.52206061).
文摘To numerically study the impact of total temperature distortion on a transonic compressor with reduced computational costs,a Body-Force Model(BFM)is developed.Firstly,the interactions between the distorted flow and the compressor are analyzed using full-annulus Unsteady Reynolds-Averaged Navier-Stokes(URANS)results and the orbit method.It is found that the induced swirl distortion and the mass flux nonuniformity are intensified in the compressor upstream flow field.A correction factor is thus added to the BFM to account for the effect of the induced swirl,which is crucial for the accurate representation of distortion transfer in the intake.Then,steady simulations with large-amplitude 180circumferential total temperature distortion are performed using the developed BFM.It is shown that the distorted compressor map simulated with the BFM matches well with URANS results.The circumferential phase shift of total temperature and the generation of the additional total pressure distortion across the rotor are in line with the time-averaged URANS flow field.The compressor upstream effects on the distorted inflow can also be exactly captured.All above-mentioned results demonstrate the BFM developed in this paper can effectively capture the distorted flow features inside the compressor,and significantly reduce the computational costs by five orders of magnitude compared with URANS.
文摘Grew up in this paper, in view of the urban rail transit ramp section, from the viewpoint of energy saving and increase contact line voltage index, the paper puts forward a kind appropriate location in the traction power supply division set up, the concrete implementation plan of the downlink power supply in parallel. At the same time, it puts forward a corresponding bilateral jump does not affect both the dc traction power supply system protection function, safe and reliable to achieve multichannel parallel protection scheme and the running safety and energy saving effect was analyzed.
文摘Peninsular Malaysia is already well known for having rare earth(RE)resources.However,pertinent data and information on upstream RE resources and reserve potential in Malaysia are yet to be established.It is vital to identify opportunities and challenges for value addition to rare earth elements(REEs)deposits in Malaysia.Therefore,this study evaluates the potential of Malaysian geological formations to serve as repositories for RE resources,such as rare earth minerals(REMs)and REEs,by elucidating the geological processes that are considered critical to the formation of the various deposit types.This paper concisely reviews possible REE mineralization in alkaline igneous rocks,pegmatites,placer deposits:monazite and xenotime,marine sediments,river and lake sediments,ion adsorption clays(IAC)deposits,and shale/coal deposits found in Malaysia.Comparisons between Malaysian deposits revealed that these deposits are potentially enriched with RE resources showing geological formations across the world.The paper reviews the methods and flowsheets used for the recovery of REMs and REEs from primary,secondary as well as alternative resources,with special consideration to the hydrometallurgical procedures comprising of leaching with acids and alkalis tailed by ion exchange,solvent extraction,or precipitation.The REEs ecosystem of Malaysia has also been discussed by considering the latest information from the Malaysian Investment Development Authority(MIDA),the REEs processing center,the Academy of Science of Malaysia(ASM),the People’s Republic of China(PRC),Lynas Malaysia Sdn.Bhd.(Lynas),Ministry of Energy and Natural Resources(NRECC),Jabatan Mineral&Geosains(JMG),Ministry of Science,Technology,and Innovation(MOSTI),and the Malaysian Chamber of Mines.The information on upstream RE resources and recent hydrometallurgical approaches provided in this study will contribute to developing and enhancing midstream and downstream RE-based manufacturing and processing operations in Malaysia.
基金the National Natural Science Foundation of China(Grant Nos.42205059 and 42005075)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDA23090303 and XDB40010302)+1 种基金the State Key Laboratory of Cryospheric Science(Grant No.SKLCS-ZZ-2024 and SKLCS-ZZ-2023)the Key Laboratory of Mountain Hazards and Earth Surface Processes.
文摘Little is known about the mechanism of climate-vegetation coverage coupled changes in the Tibetan Plateau(TP)region,which is the most climatically sensitive and ecologically fragile region with the highest terrain in the world.This study,using multisource datasets(including satellite data and meteorological observations and reanalysis data)revealed the mutual feedback mechanisms between changes in climate(temperature and precipitation)and vegetation coverage in recent decades in the Hengduan Mountains Area(HMA)of the southeastern TP and their influences on climate in the downstream region,the Sichuan Basin(SCB).There is mutual facilitation between rising air temperature and increasing vegetation coverage in the HMA,which is most significant during winter,and then during spring,but insignificant during summer and autumn.Rising temperature significantly enhances local vegetation coverage,and vegetation greening in turn heats the atmosphere via enhancing net heat flux from the surface to the atmosphere.The atmospheric heating anomaly over the HMA thickens the atmospheric column and increases upper air pressure.The high pressure anomaly disperses downstream via the westerly flow,expands across the SCB,and eventually increases the SCB temperature.This effect lasts from winter to the following spring,which may cause the maximum increasing trend of the SCB temperature and vegetation coverage in spring.These results are helpful for estimating future trends in climate and eco-environmental variations in the HMA and SCB under warming scenarios,as well as seasonal forecasting based on the connection between the HMA eco-environment and SCB climate.
基金The Second Tibetan Plateau Scientific Expedition and Research Program(STEP),No.2019QZKK0902Key Research and Development Program of Xizang Autonomous Region,No.XZ202301ZY0039GNational Natural Science Foundation of China,No.42305178,No.91747207,No.41790434。
文摘Glaciers in the Yarlung Zangbo Downstream Basin(YZDB)are sensitive to global climate change.The equilibrium-line altitude(ELA)is a key indicator of glacial development.Current models for simulating the meteorological ELA underestimate the extent of glacial advance during the Last Glacial Maximum(LGM)in the YZDB and cannot explain the large-scale glacial extension compared with the Yarlung Zangbo Midstream Basin(YZMB).In this study,the distribution of ELA in the LGM is reconstructed using high-resolution 80-km ECHAM5 simulations and empirical relationships between temperature and precipitation.Changes in ELA between the LGM and pre-industrial era(PI)are compared.Our simulated ELA closely fits the published field data.In the YZDB,simulated LGM ELAs range from ca.3500 m to over 4900 m,representing declines of ca.300–950 m.The ECHAM5 simulations better reflect the complex topographic features than most coarse-resolution climate models,and the ELA distribution is controlled by the spatial arrangement of river valley systems and mountain ranges and their impact on precipitation.Compared with the PI era,most of the monsoon precipitation in the LGM was concentrated in the YZDB,which is the main driver of glacial extension and the differential response of the downstream and midstream basins.
基金supported by the National Natural Science Foundation of China(Grant No.42304186)China Postdoctoral Science Foundation(2023M743466)+3 种基金the Key Research Program of Chinese Academy of Sciences(Grant No.ZDBS-SSW-TLC00103)the Key Research Program of the Institute of Geology&Geophysics,CAS(Grant No.s IGGCAS-201904,IGGCAS-202102)supported by the International Space Science Institute(ISSI)in Bern and Beijing,through ISSI/ISSI-BJ International Team project“Understanding the Mars Space Environment through Multi-Spacecraft Measurements”(ISSI Team project#23–582ISSIBJ Team project#58).
文摘Using over eight years of Mars Atmosphere and Volatile Evolutio N(MAVEN)data,from November 2014 to May 2023,we have investigated the Martian nightside ionospheric magnetic field distribution under the influence of upstream solar wind drivers,including the interplanetary magnetic field intensity(∣BIMF∣),solar wind dynamic pressure(PS W),solar extreme ultraviolet flux(EUV),and Martian seasons(L s).Our analysis reveals pronounced correlations between magnetic field residuals and both∣BIMF∣and PS W.Correlations observed with EUV flux and Ls were weaker—notably,magnetic field residuals increased during periods of high EUV flux and at Mars perihelion.We find that the IMF penetrates to an altitude of 200 km under a wide range of upstream conditions,penetrating notably deeper under high∣BIMF∣andPSWconditions.Our analysis also indicates that EUV flux and IMF cone angle have minimal impact on IMF penetration depth.Those findings provide useful constraints on the dynamic nature of Martian atmospheric escape processes and their evolution,suggesting that historical solar wind conditions may have facilitated deeper IMF penetration and higher rates of ionospheric escape than are observed now.Moreover,by establishing criteria for magnetic‘quiet’conditions,this study offers new insights into the planet’s magnetic environment under varying solar wind influences,knowledge that should help refine models of the Martian crustal magnetic field.
基金Guangdong Province Undergraduate Online Open Course Guidance Committee Research Project(2022ZXKC462)Foshan Philosophy and Social Science Planning Project(2024-GJ 037)+4 种基金Provincial First-Class Undergraduate Courses of Guangdong Provincial Education Department(Guangdong Education Gaohan[2022]No.10)Innovation Project of Guangdong Graduate Education(2022JGXM129,2022JGXM128,2023ANLK-080)Foshan University Curriculum Ideological and Political Teaching Reform and Practice Demonstration Project in 2023Quality Engineering Project of Foshan University in 2023Collaborative Education Project of the Ministry of Education in 2023(230703232312141)。
文摘In the context of emerging engineering disciplines,a hybrid teaching reform for the Bioengineering Downstream Technology course,based on ideological and political education and online open courses,is being carried out.This reform focuses on aspects such as“building a professional teacher team for ideological and political education,scientifically designing the ideological and political teaching system,innovating classroom teaching methods,and improving both formative and summative evaluation systems.”The“Craftsmanship in Education and Cultivating Soul and Roots”small private online course hybrid teaching reform for the Bioengineering Downstream Technology online open course provides a replicable model for the comprehensive implementation of ideological and political education in engineering courses and offers a reference for advancing ideological and political education and hybrid teaching reform in new engineering disciplines.
