The present study investigated the effects of cow manure ratios mixed with maize stover,rice straw,and wheat stalk at 3,2,1(total solid based,TS-based),respectively,on methane production and microbial community struct...The present study investigated the effects of cow manure ratios mixed with maize stover,rice straw,and wheat stalk at 3,2,1(total solid based,TS-based),respectively,on methane production and microbial community structure during the anaerobic co-digestion process.Results showed cow manure co-digested with maize stover,wheat stalk,and rice straw at ratios of 2,1,and 3 had the highest cumulative methane yields(272.99,153.22167.73 mL/g volatile solid(VS),respectively)and better stability(e.g.pH,volatile fatty acids(VFAs)and their component).The main microbe evolution had a similar trend which was Petrimonas and Methanosaeta in the early digestion process(Days 0-7)and then evolved into Longilinea,Ruminofilibacter,and Methanosarcina with the progress of digestion,but the relative abundance of these microbes in each reactor was different.It was worth noting that Caldicoprobacter in cow manure to maize stover ratio of 2,and to rice straw ratio of three reactors had a relatively higher proportion than reactor of cow manure to wheat stalk ratio of 1,and Hydrogenophaga was the specific bacterium in cow manure to wheat stalk ratio of 1 reactor.In addition,Petrimonas showed positive relationship with VFAs and Longilinea was the opposite.Methanosaeta and Methanobacterium contributed the most during the peak period of methane production in cow manure and maize stover co-digested reactor,and showed positive relationship with acetic acid.However,Methanosarcina and Methanospirillum made a great contribution during the peak period of methane production in cow manure co-digested with wheat stalk and rice straw reactors.These findings could provide further information on the application of cow manure co-digested with crop wastes.展开更多
As an effective livelihood approach to alleviate poverty without rural population migration, ethnic tourism has become the primary choice of economic development in ethnic areas worldwide in addition to traditional li...As an effective livelihood approach to alleviate poverty without rural population migration, ethnic tourism has become the primary choice of economic development in ethnic areas worldwide in addition to traditional livelihood approaches. This article applies the theories of livelihood to study the community evolution driven by tourism livelihood and examine three mountainous tourism communities in different stages of tourist area life cycle. Drawing on the methods of GIS spatial analysis, semi-structured interviews and questionnaires, this article proposes a sustainable livelihood framework for ethnic tourism to explore the evolution of ethnic tourism communities by identifying changes in livelihood assets(natural, financial, social, cultural and human capitals) in the process of tourism development. The results show that the development of ethnic tourism has led to changes in the increase of building land, and the diversification of land use functions with a trend of shifting from meeting local villagers' living needs to satisfying tourists, income composition and uneven distribution of tourism income spatially. Ethnic tourism also led to the deterioration of traditional social management structure, collapse of neighboring relationship, the over- commercialization and staged authenticity of ethnic culture, as well as the gradual vanish of agricultural knowledge with a trend of increasing modern business knowledge and higher education. In addition, these changes, involving livelihood assets from natural, economic, human, social and cultural aspects are interrelated and interactive, which form new evolution characters of ethnic community. This study reveals the conflicts over livelihood approaches which have formed new vulnerabilities to impact on sustainable evolution of ethnic communities. This research provides implications for achieving the sustainable development of ethnic communities with the driving force of tourism livelihood.展开更多
Community structure is one of the most has received an enormous amount of attention in recent important properties in social networks, and community detection years. In dynamic networks, the communities may evolve ove...Community structure is one of the most has received an enormous amount of attention in recent important properties in social networks, and community detection years. In dynamic networks, the communities may evolve over time so that pose more challenging tasks than in static ones. Community detection in dynamic networks is a problem which can naturally be formulated with two contradictory objectives and consequently be solved by multiobjective optimization algorithms. In this paper, a novel nmltiobjective immune algorithm is proposed to solve the community detection problem in dynamic networks. It employs the framework of nondominated neighbor immune algorithm to simultaneously optimize the modularity and normalized mutual information, which quantitatively measure the quality of the community partitions and temporal cost, respectively. The problem-specific knowledge is incorporated in genetic operators and local search to improve the effectiveness and efficiency of our method. Experimental studies based on four synthetic datasets and two real-world social networks demonstrate that our algorithm can not only find community structure and capture community evolution more accurately but also be more steadily than the state-of-the-art algorithms.展开更多
基金financially supported by the Youth Natural Science Foundation of Hebei province(Grant No.E2020204023)the Talents Introduction Plan(Grant No.YJ201831)of the Hebei Agricultural University+1 种基金the Key R&D projects of Hebei Province(Grant No.19223811D)the Forestry discipline project of Hebei Agricultural University(Grant No.XK1008601579).
文摘The present study investigated the effects of cow manure ratios mixed with maize stover,rice straw,and wheat stalk at 3,2,1(total solid based,TS-based),respectively,on methane production and microbial community structure during the anaerobic co-digestion process.Results showed cow manure co-digested with maize stover,wheat stalk,and rice straw at ratios of 2,1,and 3 had the highest cumulative methane yields(272.99,153.22167.73 mL/g volatile solid(VS),respectively)and better stability(e.g.pH,volatile fatty acids(VFAs)and their component).The main microbe evolution had a similar trend which was Petrimonas and Methanosaeta in the early digestion process(Days 0-7)and then evolved into Longilinea,Ruminofilibacter,and Methanosarcina with the progress of digestion,but the relative abundance of these microbes in each reactor was different.It was worth noting that Caldicoprobacter in cow manure to maize stover ratio of 2,and to rice straw ratio of three reactors had a relatively higher proportion than reactor of cow manure to wheat stalk ratio of 1,and Hydrogenophaga was the specific bacterium in cow manure to wheat stalk ratio of 1 reactor.In addition,Petrimonas showed positive relationship with VFAs and Longilinea was the opposite.Methanosaeta and Methanobacterium contributed the most during the peak period of methane production in cow manure and maize stover co-digested reactor,and showed positive relationship with acetic acid.However,Methanosarcina and Methanospirillum made a great contribution during the peak period of methane production in cow manure co-digested with wheat stalk and rice straw reactors.These findings could provide further information on the application of cow manure co-digested with crop wastes.
基金supported by the National Natural Science Foundation of China(Grant No.41361033)
文摘As an effective livelihood approach to alleviate poverty without rural population migration, ethnic tourism has become the primary choice of economic development in ethnic areas worldwide in addition to traditional livelihood approaches. This article applies the theories of livelihood to study the community evolution driven by tourism livelihood and examine three mountainous tourism communities in different stages of tourist area life cycle. Drawing on the methods of GIS spatial analysis, semi-structured interviews and questionnaires, this article proposes a sustainable livelihood framework for ethnic tourism to explore the evolution of ethnic tourism communities by identifying changes in livelihood assets(natural, financial, social, cultural and human capitals) in the process of tourism development. The results show that the development of ethnic tourism has led to changes in the increase of building land, and the diversification of land use functions with a trend of shifting from meeting local villagers' living needs to satisfying tourists, income composition and uneven distribution of tourism income spatially. Ethnic tourism also led to the deterioration of traditional social management structure, collapse of neighboring relationship, the over- commercialization and staged authenticity of ethnic culture, as well as the gradual vanish of agricultural knowledge with a trend of increasing modern business knowledge and higher education. In addition, these changes, involving livelihood assets from natural, economic, human, social and cultural aspects are interrelated and interactive, which form new evolution characters of ethnic community. This study reveals the conflicts over livelihood approaches which have formed new vulnerabilities to impact on sustainable evolution of ethnic communities. This research provides implications for achieving the sustainable development of ethnic communities with the driving force of tourism livelihood.
基金supported by the National High Technology Research and Development 863 Program of China under Grant No.2009AA12Z210the Program for New Century Excellent Talents in University of China under Grant No. NCET-08-0811+1 种基金the Program for New Scientific and Technological Star of Shaanxi Province of China under Grant No. 2010KJXX-03the Fundamental Research Funds for the Central Universities of China under Grant No. K50510020001
文摘Community structure is one of the most has received an enormous amount of attention in recent important properties in social networks, and community detection years. In dynamic networks, the communities may evolve over time so that pose more challenging tasks than in static ones. Community detection in dynamic networks is a problem which can naturally be formulated with two contradictory objectives and consequently be solved by multiobjective optimization algorithms. In this paper, a novel nmltiobjective immune algorithm is proposed to solve the community detection problem in dynamic networks. It employs the framework of nondominated neighbor immune algorithm to simultaneously optimize the modularity and normalized mutual information, which quantitatively measure the quality of the community partitions and temporal cost, respectively. The problem-specific knowledge is incorporated in genetic operators and local search to improve the effectiveness and efficiency of our method. Experimental studies based on four synthetic datasets and two real-world social networks demonstrate that our algorithm can not only find community structure and capture community evolution more accurately but also be more steadily than the state-of-the-art algorithms.
