This paper presents an in-depth analysis of the interference strength and required guardband width between coexistent users for distributed orthogonal frequency division multiple access （OFDMA）. In dynamic spectrum ...This paper presents an in-depth analysis of the interference strength and required guardband width between coexistent users for distributed orthogonal frequency division multiple access （OFDMA）. In dynamic spectrum access networks, the cross-band interference between spectrally adjacent users is considered harmful with frequency guardbands inserted between spectrum blocks to eliminate the interference. However, the strength of the cross-band interference depends heavily on the user heterogeneity in different OFDM configurations. The cross-band interference due to the three user heterogeneity artifacts of power heterogeneity, sampling rate heterogeneity, and symbol length heterogeneity is investigated to determine the required guardband width. Analytical and simulation results show that the greater user heterogeneity requires larger guardbands with the sampling rate heterogeneity having the greatest effect. These results can be used to assist the design of spectrum allocation strategies.展开更多
Most route choice models assume that people are completely rational.Recently,regret theory has attracted researchers'attentions because of its power to depict real travel behavior.This paper proposes a multiclass ...Most route choice models assume that people are completely rational.Recently,regret theory has attracted researchers'attentions because of its power to depict real travel behavior.This paper proposes a multiclass stochastic user equilibrium assignment model by using regret theory.All users are differentiated by their own regret aversion.The route travel disutility for users of each class is defined as a linear combination of the travel time and anticipated regret.The proposed model is formulated as a variational inequality problem and solved by using the self-regulated averaging method.The numerical results show that users'regret aversion indeed influences their route choice behavior and that users with high regret aversion are more inclined to change route choice when the traffic congestion degree varies.展开更多
Previous works on personalized recommendation mostly emphasize modeling peoples＇ diversity in potential fa- vorites into a uniform recommender. However, these recommenders always ignore the heterogeneity of users at ...Previous works on personalized recommendation mostly emphasize modeling peoples＇ diversity in potential fa- vorites into a uniform recommender. However, these recommenders always ignore the heterogeneity of users at an individual level. In this study, we propose an individualized recommender that can satisfy every user with a customized parameter. Experimental results on four benchmark datasets demonstrate that the individualized recommender can significantly improve the accuracy of recommendation. The work highlights the importance of the user heterogeneity in recommender design.展开更多
Urban researchers have maintained a constant interest in the complexity and continuity of urban space usage.Some have applied actor-network theory(ANT)to investigate the heterogeneity of spaces and present them throug...Urban researchers have maintained a constant interest in the complexity and continuity of urban space usage.Some have applied actor-network theory(ANT)to investigate the heterogeneity of spaces and present them through the networks of their users'activities.However,these accounts are predominantly limited in examining the extent to which these spaces may be heterogeneous when exploring such networks.This paper draws on recent ANT scholarship,which employs an ethnographic research conducted in a main park in a housing project at Dahiyat Al Hussein in Amman,Jordan.The findings describe the complex and unpredictable negotiations that occur with in spaces by documenting the varieties and in terrelations among user activity networks within this common and shared urban space.This research reveals the extent to which spaces,parks in this case,may be heterogeneous by unpacking their usage.The conclusions and in sights assert then ecessity of paying attention to design detail and creating designs that are responsive to evolving user activities.展开更多
基金Supported in part by the National High-Tech Research and Development (863) Program of China(Nos. 2006AA10Z261,2006AA10A301,and 2007AA100408)
文摘This paper presents an in-depth analysis of the interference strength and required guardband width between coexistent users for distributed orthogonal frequency division multiple access （OFDMA）. In dynamic spectrum access networks, the cross-band interference between spectrally adjacent users is considered harmful with frequency guardbands inserted between spectrum blocks to eliminate the interference. However, the strength of the cross-band interference depends heavily on the user heterogeneity in different OFDM configurations. The cross-band interference due to the three user heterogeneity artifacts of power heterogeneity, sampling rate heterogeneity, and symbol length heterogeneity is investigated to determine the required guardband width. Analytical and simulation results show that the greater user heterogeneity requires larger guardbands with the sampling rate heterogeneity having the greatest effect. These results can be used to assist the design of spectrum allocation strategies.
基金This research was supported in part by grants from the National Basic Research Program of China(No.2012CB725401)the Fundamental Research Funds for the Central Universities(No.YWF-16-JCTD-A-07)This work was also supported by the Excellence Foundation of BUAA for PhD Students.
文摘Most route choice models assume that people are completely rational.Recently,regret theory has attracted researchers'attentions because of its power to depict real travel behavior.This paper proposes a multiclass stochastic user equilibrium assignment model by using regret theory.All users are differentiated by their own regret aversion.The route travel disutility for users of each class is defined as a linear combination of the travel time and anticipated regret.The proposed model is formulated as a variational inequality problem and solved by using the self-regulated averaging method.The numerical results show that users'regret aversion indeed influences their route choice behavior and that users with high regret aversion are more inclined to change route choice when the traffic congestion degree varies.
基金Supported by the National Natural Science Foundation of China under Grant Nos 91646114,61602434 and 61370150the Youth Innovation Promotion Association of Chinese Academy of Sciences under Grant No 2017393
文摘Previous works on personalized recommendation mostly emphasize modeling peoples＇ diversity in potential fa- vorites into a uniform recommender. However, these recommenders always ignore the heterogeneity of users at an individual level. In this study, we propose an individualized recommender that can satisfy every user with a customized parameter. Experimental results on four benchmark datasets demonstrate that the individualized recommender can significantly improve the accuracy of recommendation. The work highlights the importance of the user heterogeneity in recommender design.
文摘Urban researchers have maintained a constant interest in the complexity and continuity of urban space usage.Some have applied actor-network theory(ANT)to investigate the heterogeneity of spaces and present them through the networks of their users'activities.However,these accounts are predominantly limited in examining the extent to which these spaces may be heterogeneous when exploring such networks.This paper draws on recent ANT scholarship,which employs an ethnographic research conducted in a main park in a housing project at Dahiyat Al Hussein in Amman,Jordan.The findings describe the complex and unpredictable negotiations that occur with in spaces by documenting the varieties and in terrelations among user activity networks within this common and shared urban space.This research reveals the extent to which spaces,parks in this case,may be heterogeneous by unpacking their usage.The conclusions and in sights assert then ecessity of paying attention to design detail and creating designs that are responsive to evolving user activities.
