To satisfy different service requirements of multiple users in the orthogo nal frequency division multiple access wireless local area network OFDMA-WLAN system downlink transmission a resource allocation algorithm bas...To satisfy different service requirements of multiple users in the orthogo nal frequency division multiple access wireless local area network OFDMA-WLAN system downlink transmission a resource allocation algorithm based on fairness and quality of service QoS provisioning is proposed. Different QoS requirements are converted into different rate requirements to calculate the QoSs atisfaction level.The optimization object is revised as a fairness-driven resource optimization function to provide fairness. The complex resource allocation problem is divided into channel allocation and power assignment sub-problems. The sub-problems are solved by the bipartite graph matching and water-filling based method.Compared with other algorithms the proposed algorithm sacrifices less data rate for higher fairnes and QoS satisfaction.The sim ulation results show that the proposed algorithm is capableo fp rovi ding QoS and fairness and performs better in a tradeoff among QoS fairness and data rate.展开更多
[Objective] In order to study plant adaptation mechanism under different landforms in drought regions.[Method] Observe soil moisture dynamic of Salix psammophila sample areas on the dune and depression with neutron mo...[Objective] In order to study plant adaptation mechanism under different landforms in drought regions.[Method] Observe soil moisture dynamic of Salix psammophila sample areas on the dune and depression with neutron moisture gauge and research the roots distribution of Salix psammophila sample areas on the dune and depression respectively by digging method.[Result] The quantity of Salix psammophila roots on the dune exponentially decreases while that on the depression decreases by power function in horizontal direction.In vertical direction,Salix psammophila roots on the dune are mainly distributed in 0-30 and 80-120 cm layers as 72% of all,while Salix psammophila roots on the depression are mainly distributed in 0-40 cm layers as 54% of all.[Conclusion] Salix psammophila roots on the dune not only use surface soil water but also use middle-layer groundwater.Salix psammophila roots on the depression primarily use surface soil water.展开更多
Based on the analysis of forest inner mechanism, forest benefit in re ducing flood disaster is defined. Through the characteristic analysis of forest benefit in reducing flood disaster, it is suggested that it is imp...Based on the analysis of forest inner mechanism, forest benefit in re ducing flood disaster is defined. Through the characteristic analysis of forest benefit in reducing flood disaster, it is suggested that it is impossible to ado pt the microanalysis method for studying the forest benefit in reducing flood, t he macro analysis is the only method to be adopted. With the special case of dis aster flooding of Changjiang River happened in 1998, the forest benefit in reduc ing flood disaster was scientifically assessed. The estimated results of forest benefit in reducing flood shows that forest vegetation establishment is the radi cal way to control flood, but it only equals to 5 percent of the total benefits of water conservancy facilities.展开更多
Xinli district of Sanshandao Gold Mine is the first subsea metal mine in China.To achieve 6 kt/d production capacity under the premise of safe mining,high-intensity mining might destroy the in-situ stress filed and th...Xinli district of Sanshandao Gold Mine is the first subsea metal mine in China.To achieve 6 kt/d production capacity under the premise of safe mining,high-intensity mining might destroy the in-situ stress filed and the stability of rockmass.According to sampling and testing of ore-rock and backfill and in-situ stress field measurement,safety factor method calculation model based on stress-strain strength reduction at arbitrary points and Mohr-Coulomb yield criterion was established and limit displacement subsidence values under the safety factor of different limit stoping steps were calculated.The results from three years in-situ mining and strata movement monitoring using multi-point displacements meter showed that the lower settlement frame stope hierarchical level filling mining method,mining sequence are reasonable and rockmass stability evaluation using safety factor method,in-situ real-time monitoring can provide the technical foundation for the safety of seabed mining.展开更多
基金The National Science and Technology Major Project(No.2012ZX03004005-003)the National Natural Science Foundationof China(No.61171081,61201175)the Science and Technology Support Program of Jiangsu Province(No.BE2011187)
文摘To satisfy different service requirements of multiple users in the orthogo nal frequency division multiple access wireless local area network OFDMA-WLAN system downlink transmission a resource allocation algorithm based on fairness and quality of service QoS provisioning is proposed. Different QoS requirements are converted into different rate requirements to calculate the QoSs atisfaction level.The optimization object is revised as a fairness-driven resource optimization function to provide fairness. The complex resource allocation problem is divided into channel allocation and power assignment sub-problems. The sub-problems are solved by the bipartite graph matching and water-filling based method.Compared with other algorithms the proposed algorithm sacrifices less data rate for higher fairnes and QoS satisfaction.The sim ulation results show that the proposed algorithm is capableo fp rovi ding QoS and fairness and performs better in a tradeoff among QoS fairness and data rate.
基金Supported by Science and Technology Research Major Project ofthe Ministry of Education (308021)Publicly-Traded Research Pro-ject of the Ministry of Land and Resources (200911004)~~
文摘[Objective] In order to study plant adaptation mechanism under different landforms in drought regions.[Method] Observe soil moisture dynamic of Salix psammophila sample areas on the dune and depression with neutron moisture gauge and research the roots distribution of Salix psammophila sample areas on the dune and depression respectively by digging method.[Result] The quantity of Salix psammophila roots on the dune exponentially decreases while that on the depression decreases by power function in horizontal direction.In vertical direction,Salix psammophila roots on the dune are mainly distributed in 0-30 and 80-120 cm layers as 72% of all,while Salix psammophila roots on the depression are mainly distributed in 0-40 cm layers as 54% of all.[Conclusion] Salix psammophila roots on the dune not only use surface soil water but also use middle-layer groundwater.Salix psammophila roots on the depression primarily use surface soil water.
基金National Foundation of Ninth Five-Yea r Plan (No. 96-007-04-06-03).
文摘Based on the analysis of forest inner mechanism, forest benefit in re ducing flood disaster is defined. Through the characteristic analysis of forest benefit in reducing flood disaster, it is suggested that it is impossible to ado pt the microanalysis method for studying the forest benefit in reducing flood, t he macro analysis is the only method to be adopted. With the special case of dis aster flooding of Changjiang River happened in 1998, the forest benefit in reduc ing flood disaster was scientifically assessed. The estimated results of forest benefit in reducing flood shows that forest vegetation establishment is the radi cal way to control flood, but it only equals to 5 percent of the total benefits of water conservancy facilities.
基金Project(10872218) supported by the National Natural Science Foundation of ChinaProject(2010CB732004) supported by the National Key Basic Research Program of China+1 种基金Project(20090461022) supported by the National Postdoctoral Foundation of ChinaProject (11MX21) supported by the Students' Innovation Project Aubsidize Award of Arcelor Mittal
文摘Xinli district of Sanshandao Gold Mine is the first subsea metal mine in China.To achieve 6 kt/d production capacity under the premise of safe mining,high-intensity mining might destroy the in-situ stress filed and the stability of rockmass.According to sampling and testing of ore-rock and backfill and in-situ stress field measurement,safety factor method calculation model based on stress-strain strength reduction at arbitrary points and Mohr-Coulomb yield criterion was established and limit displacement subsidence values under the safety factor of different limit stoping steps were calculated.The results from three years in-situ mining and strata movement monitoring using multi-point displacements meter showed that the lower settlement frame stope hierarchical level filling mining method,mining sequence are reasonable and rockmass stability evaluation using safety factor method,in-situ real-time monitoring can provide the technical foundation for the safety of seabed mining.
