In this paper,we explore a cooperative decode-and-forward(DF)relay network comprised of a source,a relay,and a destination in the presence of an eavesdropper.To improve physical-layer security of the relay system,we p...In this paper,we explore a cooperative decode-and-forward(DF)relay network comprised of a source,a relay,and a destination in the presence of an eavesdropper.To improve physical-layer security of the relay system,we propose a jamming aided decodeand-forward relay(JDFR)scheme combining the use of artificial noise and DF relaying which requires two stages to transmit a packet.Specifically,in stage one,the source sends confidential message to the relay while the destination acts as a friendly jammer and transmits artificial noise to confound the eavesdropper.In stage two,the relay forwards its re-encoded message to the destination while the source emits artificial noise to confuse the eavesdropper.In addition,we analyze the security-reliability tradeoff(SRT)performance of the proposed JDFR scheme,where security and reliability are evaluated by deriving intercept probability(IP)and outage probability(OP),respectively.For the purpose of comparison,SRT of the traditional decode-and-forward relay(TDFR)scheme is also analyzed.Numerical results show that the SRT performance of the proposed JDFR scheme is better than that of the TDFR scheme.Also,it is shown that for the JDFR scheme,a better SRT performance can be obtained by the optimal power allocation(OPA)between the friendly jammer and user.展开更多
Ecosystem services(ESs)refer to the continuous provisioning of ecosystem goods and services that benefit human beings.Over recent decades,rapid urbanization has exerted significant pressure on coastal ecosystems,resul...Ecosystem services(ESs)refer to the continuous provisioning of ecosystem goods and services that benefit human beings.Over recent decades,rapid urbanization has exerted significant pressure on coastal ecosystems,resulting in biodiversity and habitat loss,environmental pollution,and the depletion of natural resources.In response to these environmental challenges,the Sustainable Development Goals(SDGs)were proposed.Given the pressing need to address these issues,understanding the changes in ESs under the SDGs is crucial for formulating specific ecological strategies.In this study,we first analyzed land use and cover change in the Zhejiang coasts of China during 2000–2020.Then,we investigated the spatiotemporal configuration of ESs by integrating carbon storage(CS),soil retention(SR),habitat quality(HQ)and water yield(WY)using the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model.The driving mechanisms of ESs,which varied by space and time,were also explored using the Geo-detector method.The results revealed that,over the past two decades:1)the Zhejiang coasts have experienced a significant increase of 2783.72 km^(2) in built-up land areas and a continuous decrease in farmland areas due to rapid urbanization;2)owing to higher precipitation,extensive vegetation cover,and reduced anthropogenic disturbances,forests emerge as a crucial land use type for maintaining ecosystem services such as HQ,CS,WY,and SR;3)ESs have generally declined across the entire Zhejiang coasts,with a significant decrease observed in the northern areas and an increase in the southern areas spatially;4)the expansion of built-up land areas emerged as the primary factor affecting ecosystem services,while the vegetation factor has been increasingly significant and is expected to become predominant in the near future.Our study provides insights of understanding of ecosystem service theory and emphasizing the importance of preserving biodiversity for long-term sustainable development,and valuable scientific references to support the ecological management decision-making for local governments.展开更多
Regional sustainable development necessitates a holistic understanding of spatiotemporal variations in ecosystem carbon storage(ECS),particularly in ecologically sensitive areas with arid and semi-arid climate.In this...Regional sustainable development necessitates a holistic understanding of spatiotemporal variations in ecosystem carbon storage(ECS),particularly in ecologically sensitive areas with arid and semi-arid climate.In this study,we calculated the ECS in the Ningxia Section of Yellow River Basin,China from 1985 to 2020 using the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model based on land use data.We further predicted the spatial distribution of ECS in 2050 under four land use scenarios:natural development scenario(NDS),ecological protection scenario(EPS),cultivated land protection scenario(CPS),and urban development scenario(UDS)using the patch-generating land use simulation(PLUS)model,and quantified the influences of natural and human factors on the spatial differentiation of ECS using the geographical detector(Geodetector).Results showed that the total ECS of the study area initially increased from 1985 until reaching a peak at 402.36×10^(6) t in 2010,followed by a decreasing trend to 2050.The spatial distribution of ECS was characterized by high values in the eastern and southern parts of the study area,and low values in the western and northern parts.Between 1985 and 2020,land use changes occurred mainly through the expansion of cultivated land,woodland,and construction land at the expense of unused land.The total ECS in 2050 under different land use scenarios(ranked as EPS>CPS>NDS>UDS)would be lower than that in 2020.Nighttime light was the largest contributor to the spatial differentiation of ECS,with soil type and annual mean temperature being the major natural driving factors.Findings of this study could provide guidance on the ecological construction and high-quality development in arid and semi-arid areas.展开更多
There has been growing attention to intraspecific variation in trait-based plant ecology. However, studies on these changes across ontogenetic stages and the potential trade-offs with interspecific traits along enviro...There has been growing attention to intraspecific variation in trait-based plant ecology. However, studies on these changes across ontogenetic stages and the potential trade-offs with interspecific traits along environmental gradients are rare. In this study, we measured six wood and bark traits of 1030 trees of six species(Castanopsis nigrescens; C. carlesii; Lithocarpus polystachyus; L. synbalanos; Ormosia glaberrima; O. pachycarpa) from a10-ha plot in a subtropical forest. Mean intraspecific variation in bark thickness and bark percentage to DBH was more than twice that for wood density and bark density.Bark thickness and bark percentage showed a consistent trend with increasing tree size. Small-tree traits were more variable than the same traits in larger trees. Altitude,convexity and soil nutrients explained the majority of the variations in the six traits, while sibling species had similar relationships between traits and environmental variables.Trees with dense wood and thin bark were usually found on steep slopes at lower altitudes. Our findings show intraspecific trait variability has different spatial patterns compared with interspecific variabilities along an environmental gradient.展开更多
Under the influence of various natural and human factors, the relationship between the ecosystem services provided for human beings by a karst ecosystem is becoming increasingly complex, profoundly limiting the effect...Under the influence of various natural and human factors, the relationship between the ecosystem services provided for human beings by a karst ecosystem is becoming increasingly complex, profoundly limiting the effective and sustainable development of the social economy and ecosystem protection in karst areas. Taking Guizhou, China as an example, which includes both karst(including five different landforms) and non-karst area, the study explored and compared the tradeoff and synergy between ecosystem services in both terrain types. The results showed higher change rates of water yield and soil retention in karst areas than those in non-karst areas, with only small differences in the carbon storage and crop production change. The ecosystem service relationships in the karst area from 1995 to 2005 were consistent with the relationships in the non-karst area. However, differences were observed in most of these relationships from 2005 to 2015. The relationships between ecosystem services in different karst landforms from 1995 to 2005 remained the same, but there are differences found in the relationships of ecosystem services from 2005 to 2015. The trade-off and synergistic relationships between ecosystem services in the different landforms were closely related to the changes of climate and land use, particularly related to rainfall, rainfall erosivity, farmland, and forestland.展开更多
While the Network Coding cooperative relaying (NC-relaying) has the merit of high spectral efficiency,Superposition Coding relaying (SC-relaying) has the merit of high throughput. In this paper,a novel concept,coded c...While the Network Coding cooperative relaying (NC-relaying) has the merit of high spectral efficiency,Superposition Coding relaying (SC-relaying) has the merit of high throughput. In this paper,a novel concept,coded cooperative relaying,is presented,which is a unified scheme of the NC-relaying and SC-relaying. For the SC-relaying strategy which can be considered one-way coded relaying scheme with multi-access channel,the close-form solution of the outage probabilities of the basic signal and additional signal are obtained firstly. Secondly,the Diversity-and-Multiplexing Tradeoff (DMT) characteristics of basic signal and additional signal are investigated entirely as well as the optimal close-form solutions. The compared numerical analysis shows the evaluation error of throughput based on the close-form solution is about 0.15 nats,which is within the acceptable error range. Due to the mutual effect between the both source signals,the available maximal values of the two multiplexing gains are less than 1.展开更多
Although the quantification and valuation of ecosystem services have been studied for a long time, few studies have specifically focused on the quantification of tradeoffs between ecosystem services and tradeoff hotsp...Although the quantification and valuation of ecosystem services have been studied for a long time, few studies have specifically focused on the quantification of tradeoffs between ecosystem services and tradeoff hotspots. Based on previous studies of ecosystem service assessment, we proposed a feasible method to analyze the tradeoffs between ecosystem services, including determination of their relationship, quantification of tradeoffs, and identification of tradeoff hotspots. Potential influencing factors were then further analyzed. The Yanhe Basin in the Loess Plateau was selected as an example to demonstrate the application process. Firstly, the amounts of net primary production(NPP) and water yield(WY) in 2000 and 2008 were estimated by using biophysical models. Secondly, correlation analysis was used to indicate the tradeoffs between NPP and WY. Thirdly, tradeoff index(TI_(NPP/WY)) was established to quantify the extent of tradeoffs between NPP and WY, and the average value of TI_(NPP/WY) is 24.4 g/(mm·m^2) for the Yanhe Basin between 2000 and 2008. Finally, the tradeoff hotspots were identified. The results indicated that the area of lowest tradeoff index concentrated in the middle part of the Yanhe Basin and marginal areas of the southern basin. Map overlapping was used for preliminary analysis to seek potential influencing factors, and the results showed that shrub was the best suited for growing in the Yanhe Basin, but also was a potential influencing factor for formulation of the tradeoff hotspots. The concept of tradeoff index could also be used to quantify the degree of synergy between different ecosystem services. The method to identify the tradeoff hotspots could help us to narrow the scope of study area for further research on the relationship among ecosystem services and concentrate on the potential factors for formation of tradeoff between ecosystem services, enhance the capacity to maintain the sustainability of ecosystem.展开更多
基金supported in part by the National Natural Science Foundation of China under Grant 62271268,Grant 62071253,and Grant 62371252in part by the Jiangsu Provincial Key Research and Development Program under Grant BE2022800in part by the Jiangsu Provincial 333 Talent Project。
文摘In this paper,we explore a cooperative decode-and-forward(DF)relay network comprised of a source,a relay,and a destination in the presence of an eavesdropper.To improve physical-layer security of the relay system,we propose a jamming aided decodeand-forward relay(JDFR)scheme combining the use of artificial noise and DF relaying which requires two stages to transmit a packet.Specifically,in stage one,the source sends confidential message to the relay while the destination acts as a friendly jammer and transmits artificial noise to confound the eavesdropper.In stage two,the relay forwards its re-encoded message to the destination while the source emits artificial noise to confuse the eavesdropper.In addition,we analyze the security-reliability tradeoff(SRT)performance of the proposed JDFR scheme,where security and reliability are evaluated by deriving intercept probability(IP)and outage probability(OP),respectively.For the purpose of comparison,SRT of the traditional decode-and-forward relay(TDFR)scheme is also analyzed.Numerical results show that the SRT performance of the proposed JDFR scheme is better than that of the TDFR scheme.Also,it is shown that for the JDFR scheme,a better SRT performance can be obtained by the optimal power allocation(OPA)between the friendly jammer and user.
基金Under the auspices of the National Natural Science Fundation (No.41901121,42276234)Open Funding of Zhejiang Collaborative Innovation Center for Land and Marine Spatial Utilization and Governance Research (No.LHGTXT-2024-004)+1 种基金Science and Technology Major Project of Ningbo (No.2022Z181)Key Laboratory of Coastal Zone Exploitation and Protection,Ministry of Natural Resources (No.2023CZEPK04)。
文摘Ecosystem services(ESs)refer to the continuous provisioning of ecosystem goods and services that benefit human beings.Over recent decades,rapid urbanization has exerted significant pressure on coastal ecosystems,resulting in biodiversity and habitat loss,environmental pollution,and the depletion of natural resources.In response to these environmental challenges,the Sustainable Development Goals(SDGs)were proposed.Given the pressing need to address these issues,understanding the changes in ESs under the SDGs is crucial for formulating specific ecological strategies.In this study,we first analyzed land use and cover change in the Zhejiang coasts of China during 2000–2020.Then,we investigated the spatiotemporal configuration of ESs by integrating carbon storage(CS),soil retention(SR),habitat quality(HQ)and water yield(WY)using the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model.The driving mechanisms of ESs,which varied by space and time,were also explored using the Geo-detector method.The results revealed that,over the past two decades:1)the Zhejiang coasts have experienced a significant increase of 2783.72 km^(2) in built-up land areas and a continuous decrease in farmland areas due to rapid urbanization;2)owing to higher precipitation,extensive vegetation cover,and reduced anthropogenic disturbances,forests emerge as a crucial land use type for maintaining ecosystem services such as HQ,CS,WY,and SR;3)ESs have generally declined across the entire Zhejiang coasts,with a significant decrease observed in the northern areas and an increase in the southern areas spatially;4)the expansion of built-up land areas emerged as the primary factor affecting ecosystem services,while the vegetation factor has been increasingly significant and is expected to become predominant in the near future.Our study provides insights of understanding of ecosystem service theory and emphasizing the importance of preserving biodiversity for long-term sustainable development,and valuable scientific references to support the ecological management decision-making for local governments.
基金supported by the Innovation Projects for Overseas Returnees of Ningxia Hui Autonomous Region-Study on Multi-Scenario Land Use Optimization and Carbon Storage in the Ningxia Section of Yellow River Basin(202303)the National Natural Science Foundation of China(42067022,41761066)the Natural Science Foundation of Ningxia Hui Autonomous Region,China(2022AAC03024)。
文摘Regional sustainable development necessitates a holistic understanding of spatiotemporal variations in ecosystem carbon storage(ECS),particularly in ecologically sensitive areas with arid and semi-arid climate.In this study,we calculated the ECS in the Ningxia Section of Yellow River Basin,China from 1985 to 2020 using the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model based on land use data.We further predicted the spatial distribution of ECS in 2050 under four land use scenarios:natural development scenario(NDS),ecological protection scenario(EPS),cultivated land protection scenario(CPS),and urban development scenario(UDS)using the patch-generating land use simulation(PLUS)model,and quantified the influences of natural and human factors on the spatial differentiation of ECS using the geographical detector(Geodetector).Results showed that the total ECS of the study area initially increased from 1985 until reaching a peak at 402.36×10^(6) t in 2010,followed by a decreasing trend to 2050.The spatial distribution of ECS was characterized by high values in the eastern and southern parts of the study area,and low values in the western and northern parts.Between 1985 and 2020,land use changes occurred mainly through the expansion of cultivated land,woodland,and construction land at the expense of unused land.The total ECS in 2050 under different land use scenarios(ranked as EPS>CPS>NDS>UDS)would be lower than that in 2020.Nighttime light was the largest contributor to the spatial differentiation of ECS,with soil type and annual mean temperature being the major natural driving factors.Findings of this study could provide guidance on the ecological construction and high-quality development in arid and semi-arid areas.
基金funded by the National Natural Science Foundation of China(Key Projects 31230013,31361140363)the Zhang-Hongda Science Foundation at Sun Yat-sen University
文摘There has been growing attention to intraspecific variation in trait-based plant ecology. However, studies on these changes across ontogenetic stages and the potential trade-offs with interspecific traits along environmental gradients are rare. In this study, we measured six wood and bark traits of 1030 trees of six species(Castanopsis nigrescens; C. carlesii; Lithocarpus polystachyus; L. synbalanos; Ormosia glaberrima; O. pachycarpa) from a10-ha plot in a subtropical forest. Mean intraspecific variation in bark thickness and bark percentage to DBH was more than twice that for wood density and bark density.Bark thickness and bark percentage showed a consistent trend with increasing tree size. Small-tree traits were more variable than the same traits in larger trees. Altitude,convexity and soil nutrients explained the majority of the variations in the six traits, while sibling species had similar relationships between traits and environmental variables.Trees with dense wood and thin bark were usually found on steep slopes at lower altitudes. Our findings show intraspecific trait variability has different spatial patterns compared with interspecific variabilities along an environmental gradient.
基金supported by the Science and Technology Foundation of Guizhou Province(NO.[2020]1Y152)the Humanity and Social Science Youth foundation of the Ministry of Education(18YJCZH042)the Scientific Research Foundation of the Guizhou Institute of Technology
文摘Under the influence of various natural and human factors, the relationship between the ecosystem services provided for human beings by a karst ecosystem is becoming increasingly complex, profoundly limiting the effective and sustainable development of the social economy and ecosystem protection in karst areas. Taking Guizhou, China as an example, which includes both karst(including five different landforms) and non-karst area, the study explored and compared the tradeoff and synergy between ecosystem services in both terrain types. The results showed higher change rates of water yield and soil retention in karst areas than those in non-karst areas, with only small differences in the carbon storage and crop production change. The ecosystem service relationships in the karst area from 1995 to 2005 were consistent with the relationships in the non-karst area. However, differences were observed in most of these relationships from 2005 to 2015. The relationships between ecosystem services in different karst landforms from 1995 to 2005 remained the same, but there are differences found in the relationships of ecosystem services from 2005 to 2015. The trade-off and synergistic relationships between ecosystem services in the different landforms were closely related to the changes of climate and land use, particularly related to rainfall, rainfall erosivity, farmland, and forestland.
基金Supported by the 973 Project of China (No.2007CB 310607)the 863 Key Project of "Key Technologies and System for Trunk Communication Based on TD-SCDMA" of China (No.2009AA011302)the Open Research Fund of National Mobile Communications Research Lab,Southeast University (N200604)
文摘While the Network Coding cooperative relaying (NC-relaying) has the merit of high spectral efficiency,Superposition Coding relaying (SC-relaying) has the merit of high throughput. In this paper,a novel concept,coded cooperative relaying,is presented,which is a unified scheme of the NC-relaying and SC-relaying. For the SC-relaying strategy which can be considered one-way coded relaying scheme with multi-access channel,the close-form solution of the outage probabilities of the basic signal and additional signal are obtained firstly. Secondly,the Diversity-and-Multiplexing Tradeoff (DMT) characteristics of basic signal and additional signal are investigated entirely as well as the optimal close-form solutions. The compared numerical analysis shows the evaluation error of throughput based on the close-form solution is about 0.15 nats,which is within the acceptable error range. Due to the mutual effect between the both source signals,the available maximal values of the two multiplexing gains are less than 1.
基金Under the auspices of National Natural Sciences Foundation of China(No.41230745)Major Program of High Resolution Earth Observation System(No.30-Y30B13-9003-14/16-02)
文摘Although the quantification and valuation of ecosystem services have been studied for a long time, few studies have specifically focused on the quantification of tradeoffs between ecosystem services and tradeoff hotspots. Based on previous studies of ecosystem service assessment, we proposed a feasible method to analyze the tradeoffs between ecosystem services, including determination of their relationship, quantification of tradeoffs, and identification of tradeoff hotspots. Potential influencing factors were then further analyzed. The Yanhe Basin in the Loess Plateau was selected as an example to demonstrate the application process. Firstly, the amounts of net primary production(NPP) and water yield(WY) in 2000 and 2008 were estimated by using biophysical models. Secondly, correlation analysis was used to indicate the tradeoffs between NPP and WY. Thirdly, tradeoff index(TI_(NPP/WY)) was established to quantify the extent of tradeoffs between NPP and WY, and the average value of TI_(NPP/WY) is 24.4 g/(mm·m^2) for the Yanhe Basin between 2000 and 2008. Finally, the tradeoff hotspots were identified. The results indicated that the area of lowest tradeoff index concentrated in the middle part of the Yanhe Basin and marginal areas of the southern basin. Map overlapping was used for preliminary analysis to seek potential influencing factors, and the results showed that shrub was the best suited for growing in the Yanhe Basin, but also was a potential influencing factor for formulation of the tradeoff hotspots. The concept of tradeoff index could also be used to quantify the degree of synergy between different ecosystem services. The method to identify the tradeoff hotspots could help us to narrow the scope of study area for further research on the relationship among ecosystem services and concentrate on the potential factors for formation of tradeoff between ecosystem services, enhance the capacity to maintain the sustainability of ecosystem.