This paper mainly discusses the origin and deposhional features of fan-deltas and braid deltas. Fan-del-tas are storm discharge-dominated, while braid deltas are usually flashy flood-dominated. The two types ofdelta, ...This paper mainly discusses the origin and deposhional features of fan-deltas and braid deltas. Fan-del-tas are storm discharge-dominated, while braid deltas are usually flashy flood-dominated. The two types ofdelta, like common deltas, were reworked by marine processes. Delta systems are classified into nine deltatypes on the basis of the subaerial depositional processes and the nature of marine reworking. Fan-deltas and braid deltas are of great significance for petroleum exploration. In divergent-marginforeland and intraplate rift-subsided basin settings fan-deltas often form combination traps for petroleum ac-cumulation.展开更多
Natural gas is providing a larger proportion of primary energy, and will soon surpass oil to become the most important fossil fuel. There are various genetic types of natural gas of which the type that pyrolysed or cr...Natural gas is providing a larger proportion of primary energy, and will soon surpass oil to become the most important fossil fuel. There are various genetic types of natural gas of which the type that pyrolysed or cracked from humic kerogen accounts for 70% of presently discovered global natural gas reserves. The parent material of humic kerogen is higher multi-cellular plants. Investigations of offshore basins in China, Russia, Indonesia, Bangladesh, Australia, Egypt and Namibia show that river-delta systems contain the major sources of coal-type gas. Sand and mud carried by rivers form deltas at river mouths and fertile soil of these deltas encourages the long-term growth of higher plants. Autochthonous higher plants and allochthonous terrigenous phytoclasts contribute to the formation of coal, carbargilite and dark mudstone, which are potential parent materials of natural gas and the basis of coal-type gas generation.展开更多
The electric networks for the distribution to low voltage costumers can be configured in different layouts. Two main approaches are used: the European system composed by three-phase distribution transformers or the No...The electric networks for the distribution to low voltage costumers can be configured in different layouts. Two main approaches are used: the European system composed by three-phase distribution transformers or the North American system composed by single-phase distribution transformers and three-phase transformer banks of single-phase transformers. With respect to harmonic analysis, much more attention has been focused on the three-phase balanced systems arrangements than on the unbalanced four-wire delta system extensively used to supply low voltage loads of 120/240 V. Different authors have shown the three-phase power systems modeling on a phase-coordinates frame. However, the presence of significant asymmetries in the network forces the need of adding a new phase-coordinates model to represent the three-phase transformers banks of two or three single-phase transformers in its various connections. Several papers treat the use of harmonic analysis programs based on a phase-coordinates frame to study the Wye or Delta connected three-phase systems. However, the commonly used four-wire delta connected systems are not fully treated in literature. This paper presents a phase-coordinates model for the representation of the commonly used three-phase transformer banks of three or two single-phase transformers, and single-phase distribution transformers for the harmonic analysis of the four-wire delta connected systems. The harmonic analysis method based on the presented model is used to examine the characteristics of this kind of distribution system with respect to the penetration of harmonics currents from loads to the primary system.展开更多
Gas chromatography-mass spectrometry(GC-MS)was used to analyze the pentacyclic triterpenoid distributions,specifically hopane and oleanane fingerprints,in 24 crude oil samples from the Niger Delta depobelts,with the a...Gas chromatography-mass spectrometry(GC-MS)was used to analyze the pentacyclic triterpenoid distributions,specifically hopane and oleanane fingerprints,in 24 crude oil samples from the Niger Delta depobelts,with the aim of defining the petroleum system,filling history,and the age of source rock producing these oils.The results indicate that the Niger Delta oils belong to a single fluvio-deltaic petroleum system,reflecting similar source organic facies and depositional environments.Geochemical parameters,including C29/C30hopane ratios,oleanane index,Ts/Tm,(Ts/(Ts+Tm)),moretane/C30hopane ratios,and C3222S/(22S+22R)ratios,suggest oxic conditions during source rock deposition and thermal maturity of the oils.The presence of terrigenous organic matter and complex filling history are also evident and influenced by multiple phases of sedimentation,and petroleum generation.A comparative plot of geologic time(Paleogene-Neogene age)and oleanane percentage composition show that the crude oils are constrained to the chronostratigraphic ages of their respective depobelts,demonstrating the potential of oleanane-derived parameters for relative dating of hydrocarbon sources,complementing traditional index fossil methods.展开更多
We conducted a field campaign to investigate the chemical composition,sources,and light absorption of submicron aerosols(PM_(1))from early 2022 in Nanjing,China.The average concentration of PM_(1) was 31μg m^(−3),org...We conducted a field campaign to investigate the chemical composition,sources,and light absorption of submicron aerosols(PM_(1))from early 2022 in Nanjing,China.The average concentration of PM_(1) was 31μg m^(−3),organics(33%)constituted the largest fraction,followed by nitrate(30%),sulfate(18%),ammonium(15%),chloride(3%),and rBC(2%).Four organic aerosol(OA)subcomponents were identified,including two primary OA(POA)and two secondary OA(SOA).The less-oxidized SOA(LO-OOA)contributes the most to the total OA mass(59%).LO-OOA is tightly correlated with the tracer ion C_(2)H_(4)O_(2)^(+)from levoglucosan,and another aged biomass-burning derived species,K_(3)SO_(4)^(+),suggesting it was likely influenced by aged biomass-burning OA.Our study also revealed that fireworks during the Spring Festival have a detrimental impact on air quality,contributing to secondary formation and accumulation under static winter meteorological conditions,prolonging the pollution duration.Also,LO-OOA was found to have the strongest light-absorbing ability.Our results highlight that the light absorption of LO-OOA can mainly be attributed to the C_(x)H_(y)N^(+) family,increased with the double-bond equivalent value.The more-oxidized SOA(MO-OOA)exhibited a negligible light absorption and was strongly correlated with daytime photochemical processes,implying a light-bleaching effect.This study enhances our understanding of the regional contribution of biomass combustion and fireworks to PM_(1) pollution in Nanjing,a typical megacity in the Yangtze River Delta region,during winter,aiding in the development of strategies for long-term air quality improvement in the region.展开更多
Gamma delta(γδ)T cells and invariant natural killer T(iNKT)cells are unconventional T cells with limited T cell receptor(TCR)diversity.Both can recognize lipid or non-peptide antigens,often through cluster of differ...Gamma delta(γδ)T cells and invariant natural killer T(iNKT)cells are unconventional T cells with limited T cell receptor(TCR)diversity.Both can recognize lipid or non-peptide antigens,often through cluster of differentiation 1d(CD1d),rapidly produce cytokines,express natural killer(NK)cell markers,and are mainly found in mucosal and barrier tissues.Acting as a bridge between innate and adaptive immunity,they show great promise for cancer immunotherapy.DevelopingγδT and iNKT cells for treatment involves shared features like thymic origin,MHC-independent recognition,rapid cytotoxicity,low graft-vs.-host disease(GvHD)risk,ex vivo expansion,and genetic modification,making them suitable for adoptive cell therapies.While their mechanisms are similar,iNKT cells rely on CD1d-mediated antigen presentation,provided by CD1d-expressing antigen-presenting cells(APCs)or engineered cell lines,to activate their invariant TCR and expand effectively.Chimeric antigen receptors(CAR)-induced functional activations make these cell types viable alternatives to conventional cell-based or CAR-T therapies with additional safety benefits.Early clinical trials have shown encouraging results,and their completion will confirm their potential for future treatments.This review explores the biology and mechanisms ofγδT and iNKT cells,focusing on how APCs,cytokines,feeder cells,and CARs contribute to boosting their cytotoxic function,cytokine production,and expansion,enhancing their promise as cancer immunotherapies.It also explores the advancements and challenges in developingγδT and iNKT cell-based immunotherapies,with preclinical and early clinical outcomes offering promising insights.展开更多
This paper studied an architecture model of turbidite channel systems based on the shallow- layer high resolution 3D seismic information in the deepwater area in the Niger Delta continental slope, West Africa as a pro...This paper studied an architecture model of turbidite channel systems based on the shallow- layer high resolution 3D seismic information in the deepwater area in the Niger Delta continental slope, West Africa as a prototype model. Different types of channel systems were identified and the corresponding architecture models were established. The controlling factors, evaluation criteria and spatial distribution of different channel systems were analyzed. This study shows that turbidite channel systems of West Africa could be classified into three types; confined, semi-confined and unconfined, according to the condition of canyon and the levees on both sides. Oil one hand, along the transport direction, channel system evolves from confined to unconfined. Within channel systems, channel complexes, including two types of incised and enveloped, are the most important reservoir bodies. On the other hand, there is a channel complex evolution from incised to enveloped vertically. The geological factors exert impacts of different levels on the architecture of the turbidite channels in different sedimentary systems or even within the same system.展开更多
On the basis of Landsat TM data of the Yangtze River Delta （YRD） Economic Zone in 1991, 2001 and 2008, this article, taking 90 counties in this region as study units, built spatial data transformation models, ecosys...On the basis of Landsat TM data of the Yangtze River Delta （YRD） Economic Zone in 1991, 2001 and 2008, this article, taking 90 counties in this region as study units, built spatial data transformation models, ecosystem service value （ESV） and coordination degree of eco-economic system （CDES） models. With the aid of ArcGIS9.3, mass grid and vector data has been processed for spatial analyses. ESV and CDES indexes have demonstrated the relationship between economic development and eco-environment system and its evolu- tion characteristics in the researched areas. Furthermore, the indexes have also been used for functional zoning and pattern recognition. Some results can be shown as follows. Firstly, since 1991, land use in the YRD has greatly changed： urban land area has increased primar- ily from original paddy land, dry land, grassland, garden plot and other land. Secondly, the ESV model has proved the deterioration trend of the YRD ecological system from 1991 to 2001 and slower degradation trend during 2001-2008. Also, it is illustrated that land-use conversion from water area and paddy field to urban area and dry land could cause great damage to ecosystem stabilization. Thirdly, GDP in the central and southern parts of the YRD is higher than that in the northern part since 1991. GDP growth rate in the central part is higher than that in the northern part during 1991-2001. This growth rate in the central part is also higher than that in the southern and northern parts of the YRD from 2001 to 2008. Fourthly, the YRD could be categorized into 12 types of subregions in terms of CDES index. According to its spatial characteristic of CDES index value in the study area, eco-economic conflict area with low CDES value which is located in the central part is surrounded by eco-coordinated areas with high CDES values. This illustrates a core-periphery spatial structure exists in the YRD. During 1991-2001, the CDES value implied the convergent de- terioration trend of eco-economic system in the study area; while it gradually stepped into coexistence of divergent deterioration and coordination during 2001-2008. Finally, this paper analyzed five subregions in the YRD, including initially degrading zone, initially coordinative zone, continuously degrading zone, coordination-declined.zone and coordination-promoted zone, based on eco-economic coordination and evolution patterns. And these subregions can be recognized and categorized by spatial transformation model.展开更多
Multiple natural and human factors in estuarine wetlands result in complicated land surface characteristics with distinct spatial and temporal heterogeneities,thereby contributing to the difficulty in identifying spat...Multiple natural and human factors in estuarine wetlands result in complicated land surface characteristics with distinct spatial and temporal heterogeneities,thereby contributing to the difficulty in identifying spatiotemporal variations and influencing factors of plant diversity.A unique estuarine wetland gradient system(UEWGS)consisting of soil,vegetation,heat,distance,landscape,and anthropogenic gradients was established based on the ecological features of estuarine wetland through remote sensing and field investigation methods.It resolved the complicated land surface characteristics,covered all aspects of factors influencing plant diversity,and possessed distinct spatiotemporal heterogeneities.The Yellow River Delta,the largest estuarine wetland in the northern China,was selected as the study area to demonstrate UEWGS in four seasons in 2017.A total of 123 species were recorded with considerable seasonal difference.Phragmites australis,Suaeda salsa,and Tamarix chinensis were the dominant species,and crop species also played important roles.In single effect,all aspects of gradients exerted significant influences,yet only vegetation gradient possessed significant influences in all seasons.In comprehensive effect,soil,vegetation,heat,and distance gradients showed significant gross influences.Moisture content in soil gradient and net primary productivity in vegetation gradient possessed significant net influences in all seasons and can be considered as the main driving factor and indicator,respectively,of plant diversity.The results validated the significance of UEWGS in revealing the plant diversity spatiotemporal characteristics and influencing factors,and UEWGS possessed universal applicability in the spatiotemporal analysis of plant diversity in estuarine areas.展开更多
In order to find out the variation process of water-sediment and its effect on the Yellow River Delta, the water discharge and sediment load at Lijin from 1950 to 2007 and the decrease of water discharge and sediment ...In order to find out the variation process of water-sediment and its effect on the Yellow River Delta, the water discharge and sediment load at Lijin from 1950 to 2007 and the decrease of water discharge and sediment load in the Yellow River Basin caused by human disturbances were analyzed by means of statistics. It was shown that the water discharge and sediment load into the sea were decreasing from 1950 to 2007 with serious fluctuation. The human activities were the main cause for decrease of water discharge and sediment load into the sea. From 1950 to 2005, the average annual reduction of water discharge and sediment load by means of water-soil conservation practices were 2.02×10^9 m^3 and 3.41×10^8 t respectively, and the average annual volume by water abstraction for industry and agriculture were 2.52×10^10 m^3 and 2.42×10^8 t respectively. The average sediment trapped by Sanmenxia Reservoir was 1.45×10^8 t from 1960 to 2007, and the average sediment retention of Xiaolangdi Reservoir was 2.398×10^8t from 1997 to 2007. Compared to the data records at Huanyuankou, the water discharge and sediment load into the sea decreased with siltation in the lower reaches and increased with scouring in the lower reaches. The coastline near river mouth extended and the delta area increased when the ratio of accumulative sediment load and accumulative water discharge into the sea （SSCT） is 25.4-26.0 kg/m^3 in different time periods. However, the sharp decrease of water discharge and sediment load into the sea in recent years, especially the Yellow River into the sea at Qing 8, the entire Yellow River Delta has turned into erosion from siltation, and the time for a reversal of the state was about 1997.展开更多
Tectonic activity occurred during the depositional period of the Enping Formation in the southern Baiyun Sag in the Pearl River Mouth Basin,with a series of synsedimentary faults and a set of large fan delta reservoir...Tectonic activity occurred during the depositional period of the Enping Formation in the southern Baiyun Sag in the Pearl River Mouth Basin,with a series of synsedimentary faults and a set of large fan delta reservoir bodies developing.There is no data from drilling,cores,etc.for this area,so this paper applies three-dimensional seismic data to study the structural style of the steep slope zone,the seismic facies characteristics of fan deltas,and the source-sink system and sedimentary model of the Enping Formation.The control action of tectonic activity on fan deltaic sedimentary systems is studied by combining interpretation of fault systems,dissection of structural styles,seismic reflection structure,seismic facies geometry,and seismic attribute analysis,together with theoretical analysis of the source-sink deposition process.The Baiyun Sag has experienced tectonic activity since the Eocene,and a series of synsedimentary faults are developed in the southern steep slope zone.Under the common control of multiple large synsedimentary faults,a large ancient gully formed in the steep slope zone in the south,which gradually widened from south to north.The uplift area in the southern part of the sag was exposed for a long time during the deposition of the Enping Formation and consequently suffered weathering and erosion.The resulting sediments were transported through a system of provenance channels composed of slopes and an ancient gully to the depression area,where they were deposited and eventually converged to form a large fan delta.The fan delta presents the overall characteristics of NS strong wedge reflection and EW strong domal reflection—thick in the middle part and thin in the wings.It displays a lobe-shaped distribution on the plane,with the fan root pointing to the south slope.According to differences in reflection intensity from bottom to top,it can be subdivided into three stages of progradational sedimentary bodies—the southern uplift and denudation zone,the large ancient gully,and the fan delta—which together constitute a complete source-sink system.This represents a sedimentary model of progradational fan delta under the overall joint control of the re stricted ancient gully and syndepositional faults.展开更多
The carbon cycle of terrestrial ecosystems is influenced by global climate change and human activities.Using remote sensing data and land cover products,the spatio-temporal variation characteristics and trends of NEP ...The carbon cycle of terrestrial ecosystems is influenced by global climate change and human activities.Using remote sensing data and land cover products,the spatio-temporal variation characteristics and trends of NEP in the Yangtze River Delta from 2000 to 2020 were analyzed based on the soil respiration model.The driving influences of ecosystem structure evolution,temperature,rainfall,and human activities on NEP were studied.The results show that the NEP shows an overall distribution pattern of high in the southeast and low in the northwest.The area of carbon sinks is larger than that of the carbon sources.NEP spatial heterogeneity is significant.NEP change trend is basically unchanged or significantly better.The future change trend in most areas will be continuous decrease.Compared with temperature,NEP are more sensitive to precipitation.The positive influence of human activities on NEP is mainly observed in north-central Anhui and northern Jiangsu coastal areas,while the negative influence is mainly found in highly urbanized areas.In the process of ecosystem structure,the contribution of unchanged areas to NEP change is greater than that of changed areas.展开更多
With consideration that the controller parameters may vary from the designed value when the controller is realized,based on Lyapunov stability theory,a design method of nonfragile guaranteed cost control for a class o...With consideration that the controller parameters may vary from the designed value when the controller is realized,based on Lyapunov stability theory,a design method of nonfragile guaranteed cost control for a class of Delta operator-formulated uncertain time-delay systems is studied.A sufficient condition for the existence of the nonfragile guaranteed cost controller is given.A numeric example is then given to illustrate the effectiveness and the feasibility of the designed method.The results show that even if the parameters of the designed controller are of variations,the closed-loop system is still asymptotically stable and the super value of the cost function can also be obtained,while the closed-loop system will be unstable if the variations of the controller parameters are not considered when the controller is designed.The nonfragile guaranteed cost controller derived from the traditional shift operator method may cause the closed-loop system to be unstable,while the nonfragile guaranteed cost controller based on Delta operator method can avoid the unstable problem of the closed-loop system.展开更多
文摘This paper mainly discusses the origin and deposhional features of fan-deltas and braid deltas. Fan-del-tas are storm discharge-dominated, while braid deltas are usually flashy flood-dominated. The two types ofdelta, like common deltas, were reworked by marine processes. Delta systems are classified into nine deltatypes on the basis of the subaerial depositional processes and the nature of marine reworking. Fan-deltas and braid deltas are of great significance for petroleum exploration. In divergent-marginforeland and intraplate rift-subsided basin settings fan-deltas often form combination traps for petroleum ac-cumulation.
基金funded by the National Science&Technology Specific Project of China(No.2011ZX05030)
文摘Natural gas is providing a larger proportion of primary energy, and will soon surpass oil to become the most important fossil fuel. There are various genetic types of natural gas of which the type that pyrolysed or cracked from humic kerogen accounts for 70% of presently discovered global natural gas reserves. The parent material of humic kerogen is higher multi-cellular plants. Investigations of offshore basins in China, Russia, Indonesia, Bangladesh, Australia, Egypt and Namibia show that river-delta systems contain the major sources of coal-type gas. Sand and mud carried by rivers form deltas at river mouths and fertile soil of these deltas encourages the long-term growth of higher plants. Autochthonous higher plants and allochthonous terrigenous phytoclasts contribute to the formation of coal, carbargilite and dark mudstone, which are potential parent materials of natural gas and the basis of coal-type gas generation.
文摘The electric networks for the distribution to low voltage costumers can be configured in different layouts. Two main approaches are used: the European system composed by three-phase distribution transformers or the North American system composed by single-phase distribution transformers and three-phase transformer banks of single-phase transformers. With respect to harmonic analysis, much more attention has been focused on the three-phase balanced systems arrangements than on the unbalanced four-wire delta system extensively used to supply low voltage loads of 120/240 V. Different authors have shown the three-phase power systems modeling on a phase-coordinates frame. However, the presence of significant asymmetries in the network forces the need of adding a new phase-coordinates model to represent the three-phase transformers banks of two or three single-phase transformers in its various connections. Several papers treat the use of harmonic analysis programs based on a phase-coordinates frame to study the Wye or Delta connected three-phase systems. However, the commonly used four-wire delta connected systems are not fully treated in literature. This paper presents a phase-coordinates model for the representation of the commonly used three-phase transformer banks of three or two single-phase transformers, and single-phase distribution transformers for the harmonic analysis of the four-wire delta connected systems. The harmonic analysis method based on the presented model is used to examine the characteristics of this kind of distribution system with respect to the penetration of harmonics currents from loads to the primary system.
文摘Gas chromatography-mass spectrometry(GC-MS)was used to analyze the pentacyclic triterpenoid distributions,specifically hopane and oleanane fingerprints,in 24 crude oil samples from the Niger Delta depobelts,with the aim of defining the petroleum system,filling history,and the age of source rock producing these oils.The results indicate that the Niger Delta oils belong to a single fluvio-deltaic petroleum system,reflecting similar source organic facies and depositional environments.Geochemical parameters,including C29/C30hopane ratios,oleanane index,Ts/Tm,(Ts/(Ts+Tm)),moretane/C30hopane ratios,and C3222S/(22S+22R)ratios,suggest oxic conditions during source rock deposition and thermal maturity of the oils.The presence of terrigenous organic matter and complex filling history are also evident and influenced by multiple phases of sedimentation,and petroleum generation.A comparative plot of geologic time(Paleogene-Neogene age)and oleanane percentage composition show that the crude oils are constrained to the chronostratigraphic ages of their respective depobelts,demonstrating the potential of oleanane-derived parameters for relative dating of hydrocarbon sources,complementing traditional index fossil methods.
基金support from the Natural Science Foundation of Jiangsu Province(Grant No.BK20240036)the National Natural Science Foundation of China(Grant Nos.U24A20515,22276099,and 22361162668)Guangxi Key Research and Development Program,China(Grant No.Guike AB24010074)。
文摘We conducted a field campaign to investigate the chemical composition,sources,and light absorption of submicron aerosols(PM_(1))from early 2022 in Nanjing,China.The average concentration of PM_(1) was 31μg m^(−3),organics(33%)constituted the largest fraction,followed by nitrate(30%),sulfate(18%),ammonium(15%),chloride(3%),and rBC(2%).Four organic aerosol(OA)subcomponents were identified,including two primary OA(POA)and two secondary OA(SOA).The less-oxidized SOA(LO-OOA)contributes the most to the total OA mass(59%).LO-OOA is tightly correlated with the tracer ion C_(2)H_(4)O_(2)^(+)from levoglucosan,and another aged biomass-burning derived species,K_(3)SO_(4)^(+),suggesting it was likely influenced by aged biomass-burning OA.Our study also revealed that fireworks during the Spring Festival have a detrimental impact on air quality,contributing to secondary formation and accumulation under static winter meteorological conditions,prolonging the pollution duration.Also,LO-OOA was found to have the strongest light-absorbing ability.Our results highlight that the light absorption of LO-OOA can mainly be attributed to the C_(x)H_(y)N^(+) family,increased with the double-bond equivalent value.The more-oxidized SOA(MO-OOA)exhibited a negligible light absorption and was strongly correlated with daytime photochemical processes,implying a light-bleaching effect.This study enhances our understanding of the regional contribution of biomass combustion and fireworks to PM_(1) pollution in Nanjing,a typical megacity in the Yangtze River Delta region,during winter,aiding in the development of strategies for long-term air quality improvement in the region.
文摘Gamma delta(γδ)T cells and invariant natural killer T(iNKT)cells are unconventional T cells with limited T cell receptor(TCR)diversity.Both can recognize lipid or non-peptide antigens,often through cluster of differentiation 1d(CD1d),rapidly produce cytokines,express natural killer(NK)cell markers,and are mainly found in mucosal and barrier tissues.Acting as a bridge between innate and adaptive immunity,they show great promise for cancer immunotherapy.DevelopingγδT and iNKT cells for treatment involves shared features like thymic origin,MHC-independent recognition,rapid cytotoxicity,low graft-vs.-host disease(GvHD)risk,ex vivo expansion,and genetic modification,making them suitable for adoptive cell therapies.While their mechanisms are similar,iNKT cells rely on CD1d-mediated antigen presentation,provided by CD1d-expressing antigen-presenting cells(APCs)or engineered cell lines,to activate their invariant TCR and expand effectively.Chimeric antigen receptors(CAR)-induced functional activations make these cell types viable alternatives to conventional cell-based or CAR-T therapies with additional safety benefits.Early clinical trials have shown encouraging results,and their completion will confirm their potential for future treatments.This review explores the biology and mechanisms ofγδT and iNKT cells,focusing on how APCs,cytokines,feeder cells,and CARs contribute to boosting their cytotoxic function,cytokine production,and expansion,enhancing their promise as cancer immunotherapies.It also explores the advancements and challenges in developingγδT and iNKT cell-based immunotherapies,with preclinical and early clinical outcomes offering promising insights.
基金supported by Open Fund(PLC201203)of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(Chengdu University of Technology)National Science and Technology Major Project(2011ZX05030-005)Major Project of Education Department in Sichuan Province(13ZA0177)
文摘This paper studied an architecture model of turbidite channel systems based on the shallow- layer high resolution 3D seismic information in the deepwater area in the Niger Delta continental slope, West Africa as a prototype model. Different types of channel systems were identified and the corresponding architecture models were established. The controlling factors, evaluation criteria and spatial distribution of different channel systems were analyzed. This study shows that turbidite channel systems of West Africa could be classified into three types; confined, semi-confined and unconfined, according to the condition of canyon and the levees on both sides. Oil one hand, along the transport direction, channel system evolves from confined to unconfined. Within channel systems, channel complexes, including two types of incised and enveloped, are the most important reservoir bodies. On the other hand, there is a channel complex evolution from incised to enveloped vertically. The geological factors exert impacts of different levels on the architecture of the turbidite channels in different sedimentary systems or even within the same system.
基金National Youth Science Foundation, No.40971101 The Major Project of Science and Technology Research for the 1 lth Five-Year Plan of China, No.2006BAJ05A06
文摘On the basis of Landsat TM data of the Yangtze River Delta （YRD） Economic Zone in 1991, 2001 and 2008, this article, taking 90 counties in this region as study units, built spatial data transformation models, ecosystem service value （ESV） and coordination degree of eco-economic system （CDES） models. With the aid of ArcGIS9.3, mass grid and vector data has been processed for spatial analyses. ESV and CDES indexes have demonstrated the relationship between economic development and eco-environment system and its evolu- tion characteristics in the researched areas. Furthermore, the indexes have also been used for functional zoning and pattern recognition. Some results can be shown as follows. Firstly, since 1991, land use in the YRD has greatly changed： urban land area has increased primar- ily from original paddy land, dry land, grassland, garden plot and other land. Secondly, the ESV model has proved the deterioration trend of the YRD ecological system from 1991 to 2001 and slower degradation trend during 2001-2008. Also, it is illustrated that land-use conversion from water area and paddy field to urban area and dry land could cause great damage to ecosystem stabilization. Thirdly, GDP in the central and southern parts of the YRD is higher than that in the northern part since 1991. GDP growth rate in the central part is higher than that in the northern part during 1991-2001. This growth rate in the central part is also higher than that in the southern and northern parts of the YRD from 2001 to 2008. Fourthly, the YRD could be categorized into 12 types of subregions in terms of CDES index. According to its spatial characteristic of CDES index value in the study area, eco-economic conflict area with low CDES value which is located in the central part is surrounded by eco-coordinated areas with high CDES values. This illustrates a core-periphery spatial structure exists in the YRD. During 1991-2001, the CDES value implied the convergent de- terioration trend of eco-economic system in the study area; while it gradually stepped into coexistence of divergent deterioration and coordination during 2001-2008. Finally, this paper analyzed five subregions in the YRD, including initially degrading zone, initially coordinative zone, continuously degrading zone, coordination-declined.zone and coordination-promoted zone, based on eco-economic coordination and evolution patterns. And these subregions can be recognized and categorized by spatial transformation model.
基金Under the auspices of the National Natural Science Foundation of China(No.41871089)the Basic Scientific Fund for National Public Research Institutes of China(No.2018Q07)+3 种基金the National Natural Science Foundation of China(No.41971119)the Natural Science Foundation of Shandong Province(No.ZR2019MD024)Shandong Province University Youth Innovation Team(No.2019KJD010)the Open Research Fund Program of Shandong Provincial Key Laboratory of Eco-Environmental Science for Yellow River Delta(No.2019KFJJ01).
文摘Multiple natural and human factors in estuarine wetlands result in complicated land surface characteristics with distinct spatial and temporal heterogeneities,thereby contributing to the difficulty in identifying spatiotemporal variations and influencing factors of plant diversity.A unique estuarine wetland gradient system(UEWGS)consisting of soil,vegetation,heat,distance,landscape,and anthropogenic gradients was established based on the ecological features of estuarine wetland through remote sensing and field investigation methods.It resolved the complicated land surface characteristics,covered all aspects of factors influencing plant diversity,and possessed distinct spatiotemporal heterogeneities.The Yellow River Delta,the largest estuarine wetland in the northern China,was selected as the study area to demonstrate UEWGS in four seasons in 2017.A total of 123 species were recorded with considerable seasonal difference.Phragmites australis,Suaeda salsa,and Tamarix chinensis were the dominant species,and crop species also played important roles.In single effect,all aspects of gradients exerted significant influences,yet only vegetation gradient possessed significant influences in all seasons.In comprehensive effect,soil,vegetation,heat,and distance gradients showed significant gross influences.Moisture content in soil gradient and net primary productivity in vegetation gradient possessed significant net influences in all seasons and can be considered as the main driving factor and indicator,respectively,of plant diversity.The results validated the significance of UEWGS in revealing the plant diversity spatiotemporal characteristics and influencing factors,and UEWGS possessed universal applicability in the spatiotemporal analysis of plant diversity in estuarine areas.
基金Special Expenses Program of Scientific Research in Marine Commonweal Industry, No.200805063Scien-tific Research Program of State Key Laboratory of Estuarine and Coastal Research, No.2008KYYW06Open-end Foundation of State Oceanic Administration Key Laboratory of Marine Sedimentology & Envi-ronmental Geology, No.MASEG200608
文摘In order to find out the variation process of water-sediment and its effect on the Yellow River Delta, the water discharge and sediment load at Lijin from 1950 to 2007 and the decrease of water discharge and sediment load in the Yellow River Basin caused by human disturbances were analyzed by means of statistics. It was shown that the water discharge and sediment load into the sea were decreasing from 1950 to 2007 with serious fluctuation. The human activities were the main cause for decrease of water discharge and sediment load into the sea. From 1950 to 2005, the average annual reduction of water discharge and sediment load by means of water-soil conservation practices were 2.02×10^9 m^3 and 3.41×10^8 t respectively, and the average annual volume by water abstraction for industry and agriculture were 2.52×10^10 m^3 and 2.42×10^8 t respectively. The average sediment trapped by Sanmenxia Reservoir was 1.45×10^8 t from 1960 to 2007, and the average sediment retention of Xiaolangdi Reservoir was 2.398×10^8t from 1997 to 2007. Compared to the data records at Huanyuankou, the water discharge and sediment load into the sea decreased with siltation in the lower reaches and increased with scouring in the lower reaches. The coastline near river mouth extended and the delta area increased when the ratio of accumulative sediment load and accumulative water discharge into the sea （SSCT） is 25.4-26.0 kg/m^3 in different time periods. However, the sharp decrease of water discharge and sediment load into the sea in recent years, especially the Yellow River into the sea at Qing 8, the entire Yellow River Delta has turned into erosion from siltation, and the time for a reversal of the state was about 1997.
基金supported by the National Science and Technology Major Project(Grant no.2016ZX05026–007–007)the National Natural Science Foundation of China(Grant no.41502127)+2 种基金the Natural Science Basic Research Plan in Shaanxi Province of China(Grant nos.2017JM40132020JQ798)the Scientific Team Foundation of Department of Geology,Northwest University,Xian。
文摘Tectonic activity occurred during the depositional period of the Enping Formation in the southern Baiyun Sag in the Pearl River Mouth Basin,with a series of synsedimentary faults and a set of large fan delta reservoir bodies developing.There is no data from drilling,cores,etc.for this area,so this paper applies three-dimensional seismic data to study the structural style of the steep slope zone,the seismic facies characteristics of fan deltas,and the source-sink system and sedimentary model of the Enping Formation.The control action of tectonic activity on fan deltaic sedimentary systems is studied by combining interpretation of fault systems,dissection of structural styles,seismic reflection structure,seismic facies geometry,and seismic attribute analysis,together with theoretical analysis of the source-sink deposition process.The Baiyun Sag has experienced tectonic activity since the Eocene,and a series of synsedimentary faults are developed in the southern steep slope zone.Under the common control of multiple large synsedimentary faults,a large ancient gully formed in the steep slope zone in the south,which gradually widened from south to north.The uplift area in the southern part of the sag was exposed for a long time during the deposition of the Enping Formation and consequently suffered weathering and erosion.The resulting sediments were transported through a system of provenance channels composed of slopes and an ancient gully to the depression area,where they were deposited and eventually converged to form a large fan delta.The fan delta presents the overall characteristics of NS strong wedge reflection and EW strong domal reflection—thick in the middle part and thin in the wings.It displays a lobe-shaped distribution on the plane,with the fan root pointing to the south slope.According to differences in reflection intensity from bottom to top,it can be subdivided into three stages of progradational sedimentary bodies—the southern uplift and denudation zone,the large ancient gully,and the fan delta—which together constitute a complete source-sink system.This represents a sedimentary model of progradational fan delta under the overall joint control of the re stricted ancient gully and syndepositional faults.
基金National Key R&D Program of China,No.2018YFD1100101。
文摘The carbon cycle of terrestrial ecosystems is influenced by global climate change and human activities.Using remote sensing data and land cover products,the spatio-temporal variation characteristics and trends of NEP in the Yangtze River Delta from 2000 to 2020 were analyzed based on the soil respiration model.The driving influences of ecosystem structure evolution,temperature,rainfall,and human activities on NEP were studied.The results show that the NEP shows an overall distribution pattern of high in the southeast and low in the northwest.The area of carbon sinks is larger than that of the carbon sources.NEP spatial heterogeneity is significant.NEP change trend is basically unchanged or significantly better.The future change trend in most areas will be continuous decrease.Compared with temperature,NEP are more sensitive to precipitation.The positive influence of human activities on NEP is mainly observed in north-central Anhui and northern Jiangsu coastal areas,while the negative influence is mainly found in highly urbanized areas.In the process of ecosystem structure,the contribution of unchanged areas to NEP change is greater than that of changed areas.
基金supported by the Natural Science Foundation of Fujian Province(No.2008J04016)
文摘With consideration that the controller parameters may vary from the designed value when the controller is realized,based on Lyapunov stability theory,a design method of nonfragile guaranteed cost control for a class of Delta operator-formulated uncertain time-delay systems is studied.A sufficient condition for the existence of the nonfragile guaranteed cost controller is given.A numeric example is then given to illustrate the effectiveness and the feasibility of the designed method.The results show that even if the parameters of the designed controller are of variations,the closed-loop system is still asymptotically stable and the super value of the cost function can also be obtained,while the closed-loop system will be unstable if the variations of the controller parameters are not considered when the controller is designed.The nonfragile guaranteed cost controller derived from the traditional shift operator method may cause the closed-loop system to be unstable,while the nonfragile guaranteed cost controller based on Delta operator method can avoid the unstable problem of the closed-loop system.
