The study was designed to investigate into the level of cassava commercialization, extent of gender effects and other factors on household commercialization index （HCI） of cassava in both rural and peri-urban areas ...The study was designed to investigate into the level of cassava commercialization, extent of gender effects and other factors on household commercialization index （HCI） of cassava in both rural and peri-urban areas of Rivers State, Nigeria. The study used a stratified random sampling technique to select 50 cassava farmers each from Etche and Ekwerre LGAs of the state （i.e. 100 farmers in all）. A set of structured questionnaire and interview schedule was used to retrieve information from the farmers. Data analysis was done using descriptive statistics, Chow test and truncated regression analysis model based on Maximum Likelihood derived from Censored Normal or TOBIT approach. It was found that significant difference exist in the HC1 of rural farmers （49%） and peri-urban （40%）. The drivers of HCI varied across the areas but on the whole it was noted that gender, farm size, distance to market, labour, farming experience, price of cassava and access to market information signiftcantly influenced the probability of expanding the scale of commercialization of cassava in the area. It was recommended that government and interested bodies should give priority to women in designing and implementing cassava commercialization programmes policies that will improve farmers access to land and also help build on capacities of the farmers to commercialize such as access to extension service, establishment of market information service （MIS）, development of market and transport infrastructure were recommended too.展开更多
A new form of producing and sharing knowledge has emerged as an international(United States of America,Asia,and Europe) research collaboration,known as the Long-Term Ecological Research(LTER) Network.Although Africa b...A new form of producing and sharing knowledge has emerged as an international(United States of America,Asia,and Europe) research collaboration,known as the Long-Term Ecological Research(LTER) Network.Although Africa boasts rich biodiversity,including endemic species,it lacks the long-term initiatives to underpin sustainable biodiversity managements.At present,climate change may exacerbate hunger and poverty concerns in addition to resulting in ecosystem degradation,land use change,and other threats in Africa.Therefore,ecosystem monitoring was suggested to understanding the effects of climate change and setting strategies to mitigate these changes.This paper aimed to investigate ecosystem monitoring ground sites and address their coverage gaps in Africa to provide a foundation for optimizing the African Ecosystem Research Network(AERN) ground sites.The geographic coordinates and characteristics of ground sites-based ecosystem monitoring were collected from various networks aligned with the LTER implementation in Africa.Additionally,climatic data and biodiversity distribution maps were retrieved from various sources.These data were used to assess the size of existing ground sites and the gaps in description,ecosystems and biomes.The results reveal that there were 1089 sites established by various networks.Among these sites,30.5%,27.5%,and 28.8% had no information of area,year of establishment,current status,respectively.However,68.0% of them had an area equal to or greater than 1 km2.Sites were created progressively over the course of the years,with 68.9% being created from 2000 to 2005.To date,only 41.5% of the sites were operational.The sites were scattered across Africa,but they were concentrated in Eastern and Southern Africa.The unbalanced distribution pattern of the sites left Central and Northern Africa hardly covered,and many unique ecosystems in Central Africa were not included.To sustain these sites,the AERN should be based on operational sites,seeking secure funding by establishing multiple partnerships.展开更多
Traditional HPC （High Performance Computing） cluster is built on top of physical machines. It is usually not practical to reassign these machines to other tasks due to the fact that software installation is time con...Traditional HPC （High Performance Computing） cluster is built on top of physical machines. It is usually not practical to reassign these machines to other tasks due to the fact that software installation is time consuming. As a result, these machines are usually dedicated for the cluster usage. Virtualization technology provides an abstract layer which allows several different operating systems （with different software packages） running on top of one physical machine. Cloud computing provides an easy way for the user to manage and interact with the computing resources （the virtual machines in this case）. In this work, we demonstrate the feasibility of building a cloud-based cluster for HPC on top of a set of desktop computers that are interconnected by means of Fast Ethernet. Our cluster has several advantages. For instance, the deployment time of the cluster is quite fast： We need only 5 min to deploy a cluster of 30 machines, Besides, several performance benchmarks have been carried out. As expected, the embarrassingly parallel problem has the linear relationship between the performance and the cluster size.展开更多
In this paper, from the two economic concepts of the price elasticity of demand and the cross elasticity of demand, under the assumption that the operator＇s management goal is to obtain the profit maximization, the a...In this paper, from the two economic concepts of the price elasticity of demand and the cross elasticity of demand, under the assumption that the operator＇s management goal is to obtain the profit maximization, the author established the mathematical model of the adjustment of the optimal price of the substituting commodity.展开更多
The demands of programmability have become more and more exigent as novel network services appear, such as E-commerce, social softwares, and online videos. Commodity multi-core CPUs have been widely applied in network...The demands of programmability have become more and more exigent as novel network services appear, such as E-commerce, social softwares, and online videos. Commodity multi-core CPUs have been widely applied in network packet processing to get high programmability and reduce the time-to-market. However,there is a great gap between the packet processing performance of commodity multi-core and that of the traditional packet processing hardware, e.g., NP(Network Process). Recently, optimization of the packet processing performance of commodity multi-cores has become a hot topic in industry and academia. In this paper, based on a detailed analysis of the packet processing procedure, firstly we identify two dominating overheads, namely the virtual-to-physical address translation and the packet buffer management. Secondly, we make a comprehensive survey on the current optimization methods. Thirdly, based on the survey, the heterogeneous architecture of the commodity multi-core + FPGA is proposed as a promising way to improve the packet processing performance.Fourthly, a novel Self-Described Buffer(SDB) management technology is introduced to eliminate the overheads of the allocation and deallocation of the packet buffers offloaded to FPGA. Then, an evaluation testbed, named PIOT(Packet I/O Testbed), is designed and implemented to evaluate the packet forwarding performance. I/O capacity of different commodity multi-core CPUs and the performance of optimization methods are assessed and compared based on PIOT. At last, the future work of packet processing optimization on multi-core CPUs is discussed.展开更多
文摘The study was designed to investigate into the level of cassava commercialization, extent of gender effects and other factors on household commercialization index （HCI） of cassava in both rural and peri-urban areas of Rivers State, Nigeria. The study used a stratified random sampling technique to select 50 cassava farmers each from Etche and Ekwerre LGAs of the state （i.e. 100 farmers in all）. A set of structured questionnaire and interview schedule was used to retrieve information from the farmers. Data analysis was done using descriptive statistics, Chow test and truncated regression analysis model based on Maximum Likelihood derived from Censored Normal or TOBIT approach. It was found that significant difference exist in the HC1 of rural farmers （49%） and peri-urban （40%）. The drivers of HCI varied across the areas but on the whole it was noted that gender, farm size, distance to market, labour, farming experience, price of cassava and access to market information signiftcantly influenced the probability of expanding the scale of commercialization of cassava in the area. It was recommended that government and interested bodies should give priority to women in designing and implementing cassava commercialization programmes policies that will improve farmers access to land and also help build on capacities of the farmers to commercialize such as access to extension service, establishment of market information service （MIS）, development of market and transport infrastructure were recommended too.
基金Under the auspices of National Natural Science Foundation of China(No.31161140355)
文摘A new form of producing and sharing knowledge has emerged as an international(United States of America,Asia,and Europe) research collaboration,known as the Long-Term Ecological Research(LTER) Network.Although Africa boasts rich biodiversity,including endemic species,it lacks the long-term initiatives to underpin sustainable biodiversity managements.At present,climate change may exacerbate hunger and poverty concerns in addition to resulting in ecosystem degradation,land use change,and other threats in Africa.Therefore,ecosystem monitoring was suggested to understanding the effects of climate change and setting strategies to mitigate these changes.This paper aimed to investigate ecosystem monitoring ground sites and address their coverage gaps in Africa to provide a foundation for optimizing the African Ecosystem Research Network(AERN) ground sites.The geographic coordinates and characteristics of ground sites-based ecosystem monitoring were collected from various networks aligned with the LTER implementation in Africa.Additionally,climatic data and biodiversity distribution maps were retrieved from various sources.These data were used to assess the size of existing ground sites and the gaps in description,ecosystems and biomes.The results reveal that there were 1089 sites established by various networks.Among these sites,30.5%,27.5%,and 28.8% had no information of area,year of establishment,current status,respectively.However,68.0% of them had an area equal to or greater than 1 km2.Sites were created progressively over the course of the years,with 68.9% being created from 2000 to 2005.To date,only 41.5% of the sites were operational.The sites were scattered across Africa,but they were concentrated in Eastern and Southern Africa.The unbalanced distribution pattern of the sites left Central and Northern Africa hardly covered,and many unique ecosystems in Central Africa were not included.To sustain these sites,the AERN should be based on operational sites,seeking secure funding by establishing multiple partnerships.
文摘Traditional HPC （High Performance Computing） cluster is built on top of physical machines. It is usually not practical to reassign these machines to other tasks due to the fact that software installation is time consuming. As a result, these machines are usually dedicated for the cluster usage. Virtualization technology provides an abstract layer which allows several different operating systems （with different software packages） running on top of one physical machine. Cloud computing provides an easy way for the user to manage and interact with the computing resources （the virtual machines in this case）. In this work, we demonstrate the feasibility of building a cloud-based cluster for HPC on top of a set of desktop computers that are interconnected by means of Fast Ethernet. Our cluster has several advantages. For instance, the deployment time of the cluster is quite fast： We need only 5 min to deploy a cluster of 30 machines, Besides, several performance benchmarks have been carried out. As expected, the embarrassingly parallel problem has the linear relationship between the performance and the cluster size.
文摘In this paper, from the two economic concepts of the price elasticity of demand and the cross elasticity of demand, under the assumption that the operator＇s management goal is to obtain the profit maximization, the author established the mathematical model of the adjustment of the optimal price of the substituting commodity.
基金supported by National High-tech R&D Program of China(863 Program)(Grant No.2015AA0156-03)National Natural Science Foundation of China(Grant No.61202483)
文摘The demands of programmability have become more and more exigent as novel network services appear, such as E-commerce, social softwares, and online videos. Commodity multi-core CPUs have been widely applied in network packet processing to get high programmability and reduce the time-to-market. However,there is a great gap between the packet processing performance of commodity multi-core and that of the traditional packet processing hardware, e.g., NP(Network Process). Recently, optimization of the packet processing performance of commodity multi-cores has become a hot topic in industry and academia. In this paper, based on a detailed analysis of the packet processing procedure, firstly we identify two dominating overheads, namely the virtual-to-physical address translation and the packet buffer management. Secondly, we make a comprehensive survey on the current optimization methods. Thirdly, based on the survey, the heterogeneous architecture of the commodity multi-core + FPGA is proposed as a promising way to improve the packet processing performance.Fourthly, a novel Self-Described Buffer(SDB) management technology is introduced to eliminate the overheads of the allocation and deallocation of the packet buffers offloaded to FPGA. Then, an evaluation testbed, named PIOT(Packet I/O Testbed), is designed and implemented to evaluate the packet forwarding performance. I/O capacity of different commodity multi-core CPUs and the performance of optimization methods are assessed and compared based on PIOT. At last, the future work of packet processing optimization on multi-core CPUs is discussed.
