Transmission control protocol （TCP） is a reli- able transport layer protocol widely used in the Internet over decades. However, the performances of existing TCP conges- tion control algorithms degrade severely in mo...Transmission control protocol （TCP） is a reli- able transport layer protocol widely used in the Internet over decades. However, the performances of existing TCP conges- tion control algorithms degrade severely in modern heteroge- neous networks with random packet losses, packet reordering and congestion. In this paper, we propose a novel TCP algo- rithm named TCP-ACC to handle all three challenges men- tioned above. It integrates 1） a real-time reorder metric for calculating the probabilities of unnecessary Fast Retransmit （FRetran） and Timeouts （TO）, 2） an improved RTT estima- tion algorithm giving more weights to packets that are sent （as opposed to received） more recently, and 3） an improved congestion control mechanism based on packet loss and re- order rate measurements. Theoretical analysis demonstrates the equilibrium throughput of TCP-ACC is much higher than traditional TCP, while maintaining good fairness with regard to other TCP algorithms in ideal network conditions. Ex- tensive experimental results using both network emulators and real network show that the algorithm achieves signifi- cant throughput improvement in heterogeneous networks as compared with other state-of-the-art algorithms.展开更多
[Objective] The aim was to analyze economic benefits of rice farmers and influential factors in China. [Method] Based on data of rice production in 565 farm households in 2009, correlation analysis was conducted on ch...[Objective] The aim was to analyze economic benefits of rice farmers and influential factors in China. [Method] Based on data of rice production in 565 farm households in 2009, correlation analysis was conducted on characters of households, input/output of rice production, condition and environment of rice production, related policies and activities with SPSS. [Result] Yield per mu, production cost, and rice price were dominant factors influencing economic benefits of rice farmers; labor force in a household, training of rice cultivation, machine rice production and rice cropping had significant effects on benefits from rice production; area of rice, family educa- tion, on-time field management, site instruction, and demonstration fields all had in- significant effects on economic benefits of rice. In addition, suggestions were pro- posed about choice of production scale, implementation of rice policies, measures of subsidy, and purchase price of rice. [Conclusion] The research provides references for rice production and improvement of economic benefits of rice farmers.展开更多
基金This work was supported by the National Science Fund for Distinguished Young Scholars of China （61125102） and the State Key Program of National Natural Science Foundation of China （Grant No. 61133008）.
文摘Transmission control protocol （TCP） is a reli- able transport layer protocol widely used in the Internet over decades. However, the performances of existing TCP conges- tion control algorithms degrade severely in modern heteroge- neous networks with random packet losses, packet reordering and congestion. In this paper, we propose a novel TCP algo- rithm named TCP-ACC to handle all three challenges men- tioned above. It integrates 1） a real-time reorder metric for calculating the probabilities of unnecessary Fast Retransmit （FRetran） and Timeouts （TO）, 2） an improved RTT estima- tion algorithm giving more weights to packets that are sent （as opposed to received） more recently, and 3） an improved congestion control mechanism based on packet loss and re- order rate measurements. Theoretical analysis demonstrates the equilibrium throughput of TCP-ACC is much higher than traditional TCP, while maintaining good fairness with regard to other TCP algorithms in ideal network conditions. Ex- tensive experimental results using both network emulators and real network show that the algorithm achieves signifi- cant throughput improvement in heterogeneous networks as compared with other state-of-the-art algorithms.
基金Supported by the National Natural Science Foundation of China (71203236)Special Fund for Agro-scientific Research in the Public Interest (201203029)the Scientific Research Expenses of Central Scientific Research Institutes (2012RG006-4)~~
文摘[Objective] The aim was to analyze economic benefits of rice farmers and influential factors in China. [Method] Based on data of rice production in 565 farm households in 2009, correlation analysis was conducted on characters of households, input/output of rice production, condition and environment of rice production, related policies and activities with SPSS. [Result] Yield per mu, production cost, and rice price were dominant factors influencing economic benefits of rice farmers; labor force in a household, training of rice cultivation, machine rice production and rice cropping had significant effects on benefits from rice production; area of rice, family educa- tion, on-time field management, site instruction, and demonstration fields all had in- significant effects on economic benefits of rice. In addition, suggestions were pro- posed about choice of production scale, implementation of rice policies, measures of subsidy, and purchase price of rice. [Conclusion] The research provides references for rice production and improvement of economic benefits of rice farmers.
