Many real-world networks have the ability to adapt themselves in response to the state of their nodes. This paper studies controlling disease spread on network with feedback mechanism, where the susceptible nodes are ...Many real-world networks have the ability to adapt themselves in response to the state of their nodes. This paper studies controlling disease spread on network with feedback mechanism, where the susceptible nodes are able to avoid contact with the infected ones by cutting their connections with probability when the density of infected nodes reaches a certain value in the network. Such feedback mechanism considers the networks＇ own adaptivity and the cost of immunization. The dynamical equations about immunization with feedback mechanism ave solved and theoretical predictions are in agreement with the results of large scale simulations. It shows that when the lethality a increases, the prevalence decreases more greatly with the same immunization g. That is, with the same cost, a better controlling result can be obtained. This approach offers an effective and practical policy to control disease spread, and also may be relevant to other similar networks.展开更多
In China, it is widely believed that teacher feedback plays a crucial role in EFL writing course, exerting a great impact on the improvement of Chinese EFL students＇ writing abilities so that teachers have been requi...In China, it is widely believed that teacher feedback plays a crucial role in EFL writing course, exerting a great impact on the improvement of Chinese EFL students＇ writing abilities so that teachers have been required to deliver feedback on students＇ writings. Teachers, consequently, spare no pains to give feedback, expecting their students would make progress in their writing, but it seems that things go contrary to their wishes. Although there are various complicated factors contributing to the situation, one of the important factors lies in the teachers, a number of whom do not grasp a systematic and effective mechanism of delivering feedback on EFL student writing. Much importance has been attached to Chinese EFL student writing, however, rare attention has been paid to conducting research on concrete ways of delivering feedback on Chinese EFL student writing in China. Therefore, this paper serves to fill the gap, mainly devoting itself to exploring concrete methods of delivering teacher feedback on EFL student writing.展开更多
The main shortcomings of direct sequence spread spectrum multiple ac-cess(DS-SSMA)communication systems are the near-far effect and multiaccess in-terferences,which impair the stability,capacity and application areas ...The main shortcomings of direct sequence spread spectrum multiple ac-cess(DS-SSMA)communication systems are the near-far effect and multiaccess in-terferences,which impair the stability,capacity and application areas of the commu-nication systems.In this paper,a new kind of multiuser detector——decorrelatingdetector with decision feedback is proposed.In linear channels,this detector can e-liminate the multiaccess interferences with low complexity.Computer simulationsverify the theoretical analysis in this paper.展开更多
在现代电力系统中,可能产生的孤岛效应一定程度上限制了光伏并网发电系统(photovoltaic grid connected power system,PV)的应用和发展,孤岛检测是光伏系统必须具备的功能。传统的滑模频率偏移法有检测效率较低、对系统发电质量影响较...在现代电力系统中,可能产生的孤岛效应一定程度上限制了光伏并网发电系统(photovoltaic grid connected power system,PV)的应用和发展,孤岛检测是光伏系统必须具备的功能。传统的滑模频率偏移法有检测效率较低、对系统发电质量影响较大等缺点,提出了一种将传统滑模频率偏移法和电压正反馈机制相结合的孤岛检测策略。分析了改进方法的工作原理,基于d q变换实现了有功电压、无功电压以及有功电流、无功电流的分离,通过与参考量做差作为反馈量,达到破坏功率平衡从而检测出孤岛的目的。仿真实验结果验证了该方法的可行性和有效性,对工程应用有一定的参考价值。展开更多
基金Project supported by the National Natural Science Foundation of China （Grant No 10375022）.
文摘Many real-world networks have the ability to adapt themselves in response to the state of their nodes. This paper studies controlling disease spread on network with feedback mechanism, where the susceptible nodes are able to avoid contact with the infected ones by cutting their connections with probability when the density of infected nodes reaches a certain value in the network. Such feedback mechanism considers the networks＇ own adaptivity and the cost of immunization. The dynamical equations about immunization with feedback mechanism ave solved and theoretical predictions are in agreement with the results of large scale simulations. It shows that when the lethality a increases, the prevalence decreases more greatly with the same immunization g. That is, with the same cost, a better controlling result can be obtained. This approach offers an effective and practical policy to control disease spread, and also may be relevant to other similar networks.
文摘In China, it is widely believed that teacher feedback plays a crucial role in EFL writing course, exerting a great impact on the improvement of Chinese EFL students＇ writing abilities so that teachers have been required to deliver feedback on students＇ writings. Teachers, consequently, spare no pains to give feedback, expecting their students would make progress in their writing, but it seems that things go contrary to their wishes. Although there are various complicated factors contributing to the situation, one of the important factors lies in the teachers, a number of whom do not grasp a systematic and effective mechanism of delivering feedback on EFL student writing. Much importance has been attached to Chinese EFL student writing, however, rare attention has been paid to conducting research on concrete ways of delivering feedback on Chinese EFL student writing in China. Therefore, this paper serves to fill the gap, mainly devoting itself to exploring concrete methods of delivering teacher feedback on EFL student writing.
文摘The main shortcomings of direct sequence spread spectrum multiple ac-cess(DS-SSMA)communication systems are the near-far effect and multiaccess in-terferences,which impair the stability,capacity and application areas of the commu-nication systems.In this paper,a new kind of multiuser detector——decorrelatingdetector with decision feedback is proposed.In linear channels,this detector can e-liminate the multiaccess interferences with low complexity.Computer simulationsverify the theoretical analysis in this paper.
