Cognitive radio(CR) can bring about remarkable improvement in spectrum utilization.Different cognition cycles have been proposed in recent years.However,most of the existing works only emphasize functional or operatio...Cognitive radio(CR) can bring about remarkable improvement in spectrum utilization.Different cognition cycles have been proposed in recent years.However,most of the existing works only emphasize functional or operational aspects of cognition cycle,regardless of other indispensable aspects and the connection between them.To deal with the emerging situation of "data rich,information vague,knowledge poor" in cognitive radio networks(CRNs),we propose the hierarchical cognition cycle(HCC) as a new transdisciplinary research field in this paper.HCC investigates a fundamental problem,which is how to manage available resources in the complex environment to meet various demands in CRN.A comprehensive theoretical framework of HCC is established in terms of the core,the essence loop,the function loop,the operation loop,and the external loop of HCC.The reduction of uncertainty in CRN is studied and several new metrics in HCC are defined.Furthermore,a few research challenges ahead are presented as well.展开更多
Objective To observe the changes on multifocal electroretinography （MfERG） in the fellow eyes of patients with high myopia without fundus lesions and rhegmatogenous retinal detachment （RRD）. Methods MfERG was perf...Objective To observe the changes on multifocal electroretinography （MfERG） in the fellow eyes of patients with high myopia without fundus lesions and rhegmatogenous retinal detachment （RRD）. Methods MfERG was performed in 66 patients （ 66 eyes） which were grouped into ： emmetropes （ n = 22 ） as the control eye ; high myopes without fundus lesions （ corrected visual acuity ≥ 1. 0, n = 15 ） ; and fellow eyes of high myopics with RRD （n = 29 ）. The first-order kernels N1, P1, N2 response density and latency were analyzed. Results When compared with the emmetropes group, the high myopes group had significantly reduced N1 , PI , and N2 wave response densities in rings 1 to 6 （ P 〈 0. 05 ）, delayed N1 wave latency in rings 3 to 6, and P1 wave latency in rings 3 to 5 （ P 〈 0. 05 ）. The fellow eyes group had significantly reduced N1, P1, and N2 wave response densities in rings 1 to 6 and significantly delayed N1 and P1 wave latencies in rings 3 to 6 （ P 〈0. 05） compared with the emmetropes group. Compared with the high myopes group, P1 wave response densities in rings 1 to 6, N1 wave response densities in rings 1,3, 4, and 6, and N2 wave response density in ring 1 were significantly decreased in the fellow eyes group （ P 〈 0. 05 ） ; whereas there were no significant differences in latencies between the two groups （P 〉0.05）. Conclusion MfERG can sensitively assess the early changes in visual function in fellow eyes in patients with RRD.展开更多
This paper proposes a high performance double-interleaved dual boost （DIDB） technique to solve the problems of high ripple current, large inductor size and the requirement of step-up transformer in many case found i...This paper proposes a high performance double-interleaved dual boost （DIDB） technique to solve the problems of high ripple current, large inductor size and the requirement of step-up transformer in many case found in the conventional DC-DC boost converter. The 3-phase grid connected converter with decoupling control give an independent control between active and reactive power using the load current feed-forward. With this technique, the disturbance rejection and the output power quality can be improved. Experiments are conducted with three case studies： 1） a test of the DIDB converter to determine current ripple and voltage gain, 2） a test of the 3-phase grid connected converter to determine DC-link voltage regulation, power factor and total harmonic distortion （THD）, and 3） a test of the overall system with a 7.5 kW wind turbine simulator by step and various input wind speeds to determine the output power at the grid side and verify the maximum peak power tracking （MPPT） performance. The results can confirm that the DIDB converter gives lower ripple current and higher voltage gain than the conventional converter. For the grid side, the 3-phase grid connected converter can regulate the DC-link with fast dynamic response to disturbance rejection and low overshoot while complying with the THD standard defined in IEEE 519-1992. In addition, the MPPT controller is able to achieve the maximum energy capture with the various input wind speeds.展开更多
With the rapidly development of rural tourism, tourism e-commerce provides an internet platform for it that promotes the combination of e-tourism and rural tourism. Based on the research on electronic information serv...With the rapidly development of rural tourism, tourism e-commerce provides an internet platform for it that promotes the combination of e-tourism and rural tourism. Based on the research on electronic information services, website features and mode of operation of rural tourism, a case study was employed to develop rural e-commerce in Hainan where its topical website type and function were studied. In this paper, questionnaire was using to identify existing problems in the perceptions and expectations of rural tourism tourists website features module, we recommend B2B2C model is proposed to develop rural tourism e-commerce in Hainan.展开更多
In the context of＂lnternet ＋＂, the development of e-commerce has promoted the development of modern logistics industry to the integration, multi-function nationalization, information nationalization, globalization ...In the context of＂lnternet ＋＂, the development of e-commerce has promoted the development of modern logistics industry to the integration, multi-function nationalization, information nationalization, globalization and greening. Modern logistics is a new industry in the service industry, which not only promotes the circulation of goods, flourishes the regional market, improves the consumption of the residents, and promotes the regional development and economic growth. This paper explores the new ideas of building modern logistics industry in Henan province by analyzing the logistics market in Henan province and the development of modern logistics industry.展开更多
A Cognitive radio communication link is possible to be interrupted easily when its physical channel suffers severe fading. Relay technology is an effective way to mitigate the fading effect of wireless channels in a n...A Cognitive radio communication link is possible to be interrupted easily when its physical channel suffers severe fading. Relay technology is an effective way to mitigate the fading effect of wireless channels in a network. Based on the highest achievable rate of the relay channels, this paper considers a cognitive radio relay network where the secondary transmitter communicates with the receiver through the best relay node under the peak power constraint of a primary receiver. Intuitively, the secondary transmission can benefit from an intermediate relay node chosen from N possible nodes. To quantify this benefit, outage probability of cognitive radio relay networks is derived and also the closed-form expressions for outage capacity and ergodic capacity of cognitive radio relay networks are obtained in Rayleigh fading channels. Numerical simulation results are provided to show that the outage capacity and ergodic capacity benefit tremendously by properly increasing the number of relaying nodes.展开更多
The violently penetration of renewables in power supply network leads to situations, by which the offer exceeds the demand. Therefore, it is necessary to include a system for processes＇ management. SmartGrid is a pla...The violently penetration of renewables in power supply network leads to situations, by which the offer exceeds the demand. Therefore, it is necessary to include a system for processes＇ management. SmartGrid is a platform over the power supply network. It is represented with its network and services, which also have to be managed. The paper aims to show the second stage of SmartGrid management modeling. It meets heterogeneous requirements of the actors--subscriber without photovoltaics, subscriber with photovoltaics, service provider, network operator, and network elements operator--to service and network management and is oriented to functional areas, covering the life cycle of power supply service： Design, Planning, Installation, Provision, Configuration, Maintenance, Performance, Accounting, Buying Up, Security and Subscriber Control. Functional models for existing networks--telecommunications--are used and they are adapted to power supply. The results are illustrated with three functional areas for service management： Accounting, Buying Up, and Performance. The synthesis of network management functions and network element management functions are similar.展开更多
基金supported by the National Key Basic Research Program of China(973 Program) under Grant No.2009CB320400the National Natural Science Foundation of China under Grants No.60932002,61172062,61301160the Natural Science Foundation of Jiangsu,China under Grant No.BK2011116
文摘Cognitive radio(CR) can bring about remarkable improvement in spectrum utilization.Different cognition cycles have been proposed in recent years.However,most of the existing works only emphasize functional or operational aspects of cognition cycle,regardless of other indispensable aspects and the connection between them.To deal with the emerging situation of "data rich,information vague,knowledge poor" in cognitive radio networks(CRNs),we propose the hierarchical cognition cycle(HCC) as a new transdisciplinary research field in this paper.HCC investigates a fundamental problem,which is how to manage available resources in the complex environment to meet various demands in CRN.A comprehensive theoretical framework of HCC is established in terms of the core,the essence loop,the function loop,the operation loop,and the external loop of HCC.The reduction of uncertainty in CRN is studied and several new metrics in HCC are defined.Furthermore,a few research challenges ahead are presented as well.
文摘Objective To observe the changes on multifocal electroretinography （MfERG） in the fellow eyes of patients with high myopia without fundus lesions and rhegmatogenous retinal detachment （RRD）. Methods MfERG was performed in 66 patients （ 66 eyes） which were grouped into ： emmetropes （ n = 22 ） as the control eye ; high myopes without fundus lesions （ corrected visual acuity ≥ 1. 0, n = 15 ） ; and fellow eyes of high myopics with RRD （n = 29 ）. The first-order kernels N1, P1, N2 response density and latency were analyzed. Results When compared with the emmetropes group, the high myopes group had significantly reduced N1 , PI , and N2 wave response densities in rings 1 to 6 （ P 〈 0. 05 ）, delayed N1 wave latency in rings 3 to 6, and P1 wave latency in rings 3 to 5 （ P 〈 0. 05 ）. The fellow eyes group had significantly reduced N1, P1, and N2 wave response densities in rings 1 to 6 and significantly delayed N1 and P1 wave latencies in rings 3 to 6 （ P 〈0. 05） compared with the emmetropes group. Compared with the high myopes group, P1 wave response densities in rings 1 to 6, N1 wave response densities in rings 1,3, 4, and 6, and N2 wave response density in ring 1 were significantly decreased in the fellow eyes group （ P 〈 0. 05 ） ; whereas there were no significant differences in latencies between the two groups （P 〉0.05）. Conclusion MfERG can sensitively assess the early changes in visual function in fellow eyes in patients with RRD.
文摘This paper proposes a high performance double-interleaved dual boost （DIDB） technique to solve the problems of high ripple current, large inductor size and the requirement of step-up transformer in many case found in the conventional DC-DC boost converter. The 3-phase grid connected converter with decoupling control give an independent control between active and reactive power using the load current feed-forward. With this technique, the disturbance rejection and the output power quality can be improved. Experiments are conducted with three case studies： 1） a test of the DIDB converter to determine current ripple and voltage gain, 2） a test of the 3-phase grid connected converter to determine DC-link voltage regulation, power factor and total harmonic distortion （THD）, and 3） a test of the overall system with a 7.5 kW wind turbine simulator by step and various input wind speeds to determine the output power at the grid side and verify the maximum peak power tracking （MPPT） performance. The results can confirm that the DIDB converter gives lower ripple current and higher voltage gain than the conventional converter. For the grid side, the 3-phase grid connected converter can regulate the DC-link with fast dynamic response to disturbance rejection and low overshoot while complying with the THD standard defined in IEEE 519-1992. In addition, the MPPT controller is able to achieve the maximum energy capture with the various input wind speeds.
文摘With the rapidly development of rural tourism, tourism e-commerce provides an internet platform for it that promotes the combination of e-tourism and rural tourism. Based on the research on electronic information services, website features and mode of operation of rural tourism, a case study was employed to develop rural e-commerce in Hainan where its topical website type and function were studied. In this paper, questionnaire was using to identify existing problems in the perceptions and expectations of rural tourism tourists website features module, we recommend B2B2C model is proposed to develop rural tourism e-commerce in Hainan.
文摘In the context of＂lnternet ＋＂, the development of e-commerce has promoted the development of modern logistics industry to the integration, multi-function nationalization, information nationalization, globalization and greening. Modern logistics is a new industry in the service industry, which not only promotes the circulation of goods, flourishes the regional market, improves the consumption of the residents, and promotes the regional development and economic growth. This paper explores the new ideas of building modern logistics industry in Henan province by analyzing the logistics market in Henan province and the development of modern logistics industry.
文摘A Cognitive radio communication link is possible to be interrupted easily when its physical channel suffers severe fading. Relay technology is an effective way to mitigate the fading effect of wireless channels in a network. Based on the highest achievable rate of the relay channels, this paper considers a cognitive radio relay network where the secondary transmitter communicates with the receiver through the best relay node under the peak power constraint of a primary receiver. Intuitively, the secondary transmission can benefit from an intermediate relay node chosen from N possible nodes. To quantify this benefit, outage probability of cognitive radio relay networks is derived and also the closed-form expressions for outage capacity and ergodic capacity of cognitive radio relay networks are obtained in Rayleigh fading channels. Numerical simulation results are provided to show that the outage capacity and ergodic capacity benefit tremendously by properly increasing the number of relaying nodes.
文摘The violently penetration of renewables in power supply network leads to situations, by which the offer exceeds the demand. Therefore, it is necessary to include a system for processes＇ management. SmartGrid is a platform over the power supply network. It is represented with its network and services, which also have to be managed. The paper aims to show the second stage of SmartGrid management modeling. It meets heterogeneous requirements of the actors--subscriber without photovoltaics, subscriber with photovoltaics, service provider, network operator, and network elements operator--to service and network management and is oriented to functional areas, covering the life cycle of power supply service： Design, Planning, Installation, Provision, Configuration, Maintenance, Performance, Accounting, Buying Up, Security and Subscriber Control. Functional models for existing networks--telecommunications--are used and they are adapted to power supply. The results are illustrated with three functional areas for service management： Accounting, Buying Up, and Performance. The synthesis of network management functions and network element management functions are similar.
