In cloud computing,the number of replicas and deployment strategy have extensive impacts on user's requirement and storage efficiency.Therefore,in this paper,a new definition of file access popularity according to...In cloud computing,the number of replicas and deployment strategy have extensive impacts on user's requirement and storage efficiency.Therefore,in this paper,a new definition of file access popularity according to users' preferences,and its prediction algorithm are provided to predict file access trend with historical data.Files are sorted by priority depending on their popularity.A mathematical model between file access popularity and the number of replicas is built so that the reliability is increased efficiently.Most importantly,we present an optimal strategy of dynamic replicas deployment based on the file access popularity strategy with the overall concern of nodes' performance and load condition.By this strategy,files with high priority will be deployed on nodes with better performance therefore higher quality of service is guaranteed.The strategy is realized in the Hadoop platform.Performance is compared with that of default strategy in Hadoop and CDRM strategy.The result shows that the proposed strategy can not only maintain the system load balance,but also supply better service performance,which is consistent with the theoretical analysis.展开更多
Reducing cost of service is an important goal for resource discovery and interaction technologies. The shortcomings of transhipment-method and hibernation-method are to increase holistic cost of service and to slower ...Reducing cost of service is an important goal for resource discovery and interaction technologies. The shortcomings of transhipment-method and hibernation-method are to increase holistic cost of service and to slower resource discovery respectively. To overcome these shortcomings, a context-aware computing-based method is developed. This method, firstly, analyzes the courses of devices using resource discovery and interaction technologies to identify some types of context related to reducing cost of service, then, chooses effective methods such as stopping broadcast and hibernation to reduce cost of service according to information supplied by the context but not the transhipment-method’s simple hibernations. The results of experiments indicate that under the worst condition this method overcomes the shortcomings of transhipment-method, makes the “poor” devices hibernate longer than hibernation-method to reduce cost of service more effectively, and discovers resources faster than hibernation-method; under the best condition it is far better than hibernation-method in all aspects.展开更多
With the improvement of agricultural mechanization equipment levels, the mechanized wheat harvesting level has been above 80% and the rate of wheat straw returned has increased significantly in the main wheat producti...With the improvement of agricultural mechanization equipment levels, the mechanized wheat harvesting level has been above 80% and the rate of wheat straw returned has increased significantly in the main wheat production of wheat of northern countryside in China. Chinese government popularized the beneficial agronomic measures in the process of wheat straw returned field by mechanization. The agronomic measure was reducing the wheat straw stubble height(WSSH) not more than 20 cm.However, local government didn't apply and disseminate the measure, because in practice the cost of fuel consumption was high, and the operation time of harvesting was longer than ever. The machinery operators and farmers needed to support extra fuel cost and time if they took government's advice. In fact, the objective subsidy policy of fuel cost on reducing WSSH was not been formulated by all levels of government. Therefore, the set of agronomic measure couldn't be popularized in main wheat production area of North China. Our research addressed to master the changing feature of fuel cost and mechanical efficiency,seeking suitable subsidy standard, providing some useful and constructive suggestions to improve subsidy policy of fuel consumption cost for national government department. The study carried out the tracking experiments of the operation efficiency and fuel costs of farm harvester in the situation of different WSSH in 2010 in Xushui District of Hebei Province. In conclusion, the operation time of harvesting decline and machinery fuel consumption cost increased along with the decreasing of WSSH. First for the older harvester, the operation efficiency would decline by 18.7% when the WSSH changed from 20 cm to 10 cm, the cost would increase 4.7%, exact cost was 152.2CNY per hectare. For the new harvester, the operation efficiency would decline by 39.9% when the WSSH changed from 20 cm to 15 cm, the cost would increase 4.6%, exact cost was 368.4CNY per hectare. We provided about 375 CNY per hectare to the mechanical operators and farmer who attended this project, and they were willing to accept the subsidies. We also put forwards some policy suggestions on promoting agronomic measures of reducing WSSH including strengthen the construction of agricultural machinery service system, practise a special fuel consumption subsidies of agricultural machinery and open up new paths for combine sales and circulation.展开更多
基金Supported by the National Natural Science Foundation of China(No.61170209,61272508,61202432,61370132,61370092)
文摘In cloud computing,the number of replicas and deployment strategy have extensive impacts on user's requirement and storage efficiency.Therefore,in this paper,a new definition of file access popularity according to users' preferences,and its prediction algorithm are provided to predict file access trend with historical data.Files are sorted by priority depending on their popularity.A mathematical model between file access popularity and the number of replicas is built so that the reliability is increased efficiently.Most importantly,we present an optimal strategy of dynamic replicas deployment based on the file access popularity strategy with the overall concern of nodes' performance and load condition.By this strategy,files with high priority will be deployed on nodes with better performance therefore higher quality of service is guaranteed.The strategy is realized in the Hadoop platform.Performance is compared with that of default strategy in Hadoop and CDRM strategy.The result shows that the proposed strategy can not only maintain the system load balance,but also supply better service performance,which is consistent with the theoretical analysis.
文摘Reducing cost of service is an important goal for resource discovery and interaction technologies. The shortcomings of transhipment-method and hibernation-method are to increase holistic cost of service and to slower resource discovery respectively. To overcome these shortcomings, a context-aware computing-based method is developed. This method, firstly, analyzes the courses of devices using resource discovery and interaction technologies to identify some types of context related to reducing cost of service, then, chooses effective methods such as stopping broadcast and hibernation to reduce cost of service according to information supplied by the context but not the transhipment-method’s simple hibernations. The results of experiments indicate that under the worst condition this method overcomes the shortcomings of transhipment-method, makes the “poor” devices hibernate longer than hibernation-method to reduce cost of service more effectively, and discovers resources faster than hibernation-method; under the best condition it is far better than hibernation-method in all aspects.
基金Supported by National Nonprofit Institute Research Grant of CAAS(IARRP-2015-7)Key Laboratory of Nonpoint Source Pollution Control,Ministry of Agriculture,P.R.China,Chinese Academy of Agricultural Sciences Science and Technology Innovation Project in 2017the Public Welfare Industry Science and Technology Projects for financing the research (no.200903011)
文摘With the improvement of agricultural mechanization equipment levels, the mechanized wheat harvesting level has been above 80% and the rate of wheat straw returned has increased significantly in the main wheat production of wheat of northern countryside in China. Chinese government popularized the beneficial agronomic measures in the process of wheat straw returned field by mechanization. The agronomic measure was reducing the wheat straw stubble height(WSSH) not more than 20 cm.However, local government didn't apply and disseminate the measure, because in practice the cost of fuel consumption was high, and the operation time of harvesting was longer than ever. The machinery operators and farmers needed to support extra fuel cost and time if they took government's advice. In fact, the objective subsidy policy of fuel cost on reducing WSSH was not been formulated by all levels of government. Therefore, the set of agronomic measure couldn't be popularized in main wheat production area of North China. Our research addressed to master the changing feature of fuel cost and mechanical efficiency,seeking suitable subsidy standard, providing some useful and constructive suggestions to improve subsidy policy of fuel consumption cost for national government department. The study carried out the tracking experiments of the operation efficiency and fuel costs of farm harvester in the situation of different WSSH in 2010 in Xushui District of Hebei Province. In conclusion, the operation time of harvesting decline and machinery fuel consumption cost increased along with the decreasing of WSSH. First for the older harvester, the operation efficiency would decline by 18.7% when the WSSH changed from 20 cm to 10 cm, the cost would increase 4.7%, exact cost was 152.2CNY per hectare. For the new harvester, the operation efficiency would decline by 39.9% when the WSSH changed from 20 cm to 15 cm, the cost would increase 4.6%, exact cost was 368.4CNY per hectare. We provided about 375 CNY per hectare to the mechanical operators and farmer who attended this project, and they were willing to accept the subsidies. We also put forwards some policy suggestions on promoting agronomic measures of reducing WSSH including strengthen the construction of agricultural machinery service system, practise a special fuel consumption subsidies of agricultural machinery and open up new paths for combine sales and circulation.
