In this paper,we consider a cognitive radio(CR) system with a single secondary user(SU) and multiple licensed channels.The SU requests a fixed number of licensed channels and must sense the licensed channels one by on...In this paper,we consider a cognitive radio(CR) system with a single secondary user(SU) and multiple licensed channels.The SU requests a fixed number of licensed channels and must sense the licensed channels one by one before transmission.By leveraging prediction based on correlation between the licensed channels,we propose a novel spectrum sensing strategy,to decide which channel is the best choice to sense in order to reduce the sensing time overhead and further improve the SU's achievable throughput.Since the correlation coefficients between the licensed channels cannot be exactly known in advance,the spectrum sensing strategy is designed based on the model-free reinforcement learning(RL).The experimental results show that the proposed spectrum sensing strategy based on reinforcement learning converges and outperforms random sensing strategy in terms of long-term statistics.展开更多
Because most people consider advertising as an irritant and a distraction and would avoid it, should there be an alternative, advertising agencies strive to utilize the interactive, demassifying, and asynchronous qual...Because most people consider advertising as an irritant and a distraction and would avoid it, should there be an alternative, advertising agencies strive to utilize the interactive, demassifying, and asynchronous qualities of newer technologies to create an appealing advertisement. The current study investigates whether college students＇ attitudes toward advertising on traditional media are different when online advertising is used, especially on Social Media Networking Sites （SMNSs）. Employing the concept of reciprocity （of replicating offline attitudes online） and the flow theory that relates one＇s concentration on an activity and its impact on other occurrences happening around him/her, 287 college students responded to a questionnaire on their perceptions of online advertising, their preferred SMNS, and the SMNS on which they would consider viewing an advertising message. The results showed that 57.8% of the participants avoid online advertising at all costs, which is similar to their offline perception of advertising. Some 42.2% reported that they may consider viewing online advertising if the attributes of relevance, interest, creativity, and interactivity are present, as in viral advertisement. In addition, among the four SMNSs reviewed--Facebook, MySpace, Twitter, and Linkedln--a majority of students indicated that Facebook is their preferred site for online advertising because it allows for creativity and they consider those messages credible, especially if their Facebook friends tagged, liked, or shared the advertisement.展开更多
Chemical processes are usually nonlinear singular systems.In this study,a soft sensor using nonlinear singular state observer is established for unknown inputs and uncertain model parameters in chemical processes,whic...Chemical processes are usually nonlinear singular systems.In this study,a soft sensor using nonlinear singular state observer is established for unknown inputs and uncertain model parameters in chemical processes,which are augmented as state variables.Based on the observability of the singular system,this paper presents a simplified observability criterion under certain conditions for unknown inputs and uncertain model parameters.When the observability is satisfied,the unknown inputs and the uncertain model parameters are estimated online by the soft sensor using augmented nonlinear singular state observer.The riser reactor of fluid catalytic cracking unit is used as an example for analysis and simulation.With the catalyst circulation rate as the only unknown input without model error,one temperature sensor at the riser reactor outlet will ensure the correct estimation for the catalyst circulation rate.However,when uncertain model parameters also exist,additional temperature sensors must be used to ensure correct estimation for unknown inputs and uncertain model parameters of chemical processes.展开更多
基金supported by National Nature Science Foundation of China(NO.61372109)
文摘In this paper,we consider a cognitive radio(CR) system with a single secondary user(SU) and multiple licensed channels.The SU requests a fixed number of licensed channels and must sense the licensed channels one by one before transmission.By leveraging prediction based on correlation between the licensed channels,we propose a novel spectrum sensing strategy,to decide which channel is the best choice to sense in order to reduce the sensing time overhead and further improve the SU's achievable throughput.Since the correlation coefficients between the licensed channels cannot be exactly known in advance,the spectrum sensing strategy is designed based on the model-free reinforcement learning(RL).The experimental results show that the proposed spectrum sensing strategy based on reinforcement learning converges and outperforms random sensing strategy in terms of long-term statistics.
文摘Because most people consider advertising as an irritant and a distraction and would avoid it, should there be an alternative, advertising agencies strive to utilize the interactive, demassifying, and asynchronous qualities of newer technologies to create an appealing advertisement. The current study investigates whether college students＇ attitudes toward advertising on traditional media are different when online advertising is used, especially on Social Media Networking Sites （SMNSs）. Employing the concept of reciprocity （of replicating offline attitudes online） and the flow theory that relates one＇s concentration on an activity and its impact on other occurrences happening around him/her, 287 college students responded to a questionnaire on their perceptions of online advertising, their preferred SMNS, and the SMNS on which they would consider viewing an advertising message. The results showed that 57.8% of the participants avoid online advertising at all costs, which is similar to their offline perception of advertising. Some 42.2% reported that they may consider viewing online advertising if the attributes of relevance, interest, creativity, and interactivity are present, as in viral advertisement. In addition, among the four SMNSs reviewed--Facebook, MySpace, Twitter, and Linkedln--a majority of students indicated that Facebook is their preferred site for online advertising because it allows for creativity and they consider those messages credible, especially if their Facebook friends tagged, liked, or shared the advertisement.
基金Supported by the National Natural Science Foundation of China （21006127）, the National Basic Research Program of China （2012CB720500） and the Science Foundation of China University of Petroleum, Beijing （KYJJ2012-05-28）.
文摘Chemical processes are usually nonlinear singular systems.In this study,a soft sensor using nonlinear singular state observer is established for unknown inputs and uncertain model parameters in chemical processes,which are augmented as state variables.Based on the observability of the singular system,this paper presents a simplified observability criterion under certain conditions for unknown inputs and uncertain model parameters.When the observability is satisfied,the unknown inputs and the uncertain model parameters are estimated online by the soft sensor using augmented nonlinear singular state observer.The riser reactor of fluid catalytic cracking unit is used as an example for analysis and simulation.With the catalyst circulation rate as the only unknown input without model error,one temperature sensor at the riser reactor outlet will ensure the correct estimation for the catalyst circulation rate.However,when uncertain model parameters also exist,additional temperature sensors must be used to ensure correct estimation for unknown inputs and uncertain model parameters of chemical processes.
