Cognitive radio is considered as an efficient way to improve the spectrum efficiency. As one of its key technologies,spectrum handoff can guarantee the transmission continuity of secondary users(SUs). In this paper,we...Cognitive radio is considered as an efficient way to improve the spectrum efficiency. As one of its key technologies,spectrum handoff can guarantee the transmission continuity of secondary users(SUs). In this paper,we address a new and more generalized spectrum handoff problem in cognitive radio networks(CRNs),by considering simultaneously energy efficiency,multiple spectrum handoffs and multiple channels. Furthermore,effects of the primary users'(PUs')arrival and service rate on the target channel sequence selection are also considered. In order to obtain the energy-efficient target channel sequence,we firstly analyze the energy consumption and the number of delivered bits per hertz in the spectrum handoff process,and formulate a ratio-type energy efficiency optimization problem,which can be transformed into a parametric problem by utilizing fractional programming. Then,we propose an algorithm combining dynamic programming with bisection(DPB)algorithm to solve the energy efficiency optimization problem. Our simulation results verify that the designed target channel sequence has better performance than the existing algorithms in terms of energy efficiency.展开更多
The Port of Durban is one of the largest ports in the Southern Hemisphere and is the main port for the Southern African region. However, the port is reaching its capacity limit and it is apparent that for South Africa...The Port of Durban is one of the largest ports in the Southern Hemisphere and is the main port for the Southern African region. However, the port is reaching its capacity limit and it is apparent that for South Africa＇s economic growth this port needs to expand. In order to expand the port needs to not only expand its waterside infrastructure but it would need to provide new logistics corridors though the city of Durban. The city of Durban has completely surrounded the port making expansion options difficult and intertwined with the planning of the city. This paper examines the various options and timelines for port expansion as well as the issues from the city perspective. Areas of possible conflict in this process revolve around traffic capacity and related road/rail infrastructure, environmental issues, social and economic impacts.展开更多
Based on the relationships between the lanes of signal-controlled intersections, we utilize the integration method of cluster analysis and stepwise regression and the integration method of cluster analysis and the pri...Based on the relationships between the lanes of signal-controlled intersections, we utilize the integration method of cluster analysis and stepwise regression and the integration method of cluster analysis and the principal component analysis method to predict the lanes＇ traffic volume of non-detector isolated controlled intersections. The results are examined by the real-time lanes＇ traffic volume data of the road network of Nanjing City. The problem of the lanes＇ traffic volume prediction of non-detector isolated signal-controlled intersections was resolved which can be widely used in urban traffic flow guidance and urban traffic control in cities.展开更多
In this paper, the H∞ control problem is investigated for a class of discrete-time switched linear systems with modal persistent dwell-time(MPDT) switching. The redundant channels are considered to use in the data tr...In this paper, the H∞ control problem is investigated for a class of discrete-time switched linear systems with modal persistent dwell-time(MPDT) switching. The redundant channels are considered to use in the data transmission to benefit the capability of overcoming the fragility of networks commonly configured by a single channel in the communication networks subject to random packet losses. In light of a new class of Lyapunov functions, the desired observer-based quasi-time-dependent controllers, which have less conservatism than the time-independent ones, are designed such that the resulting closed-loop system is exponentially mean-square stable with a guaranteed H_∞ disturbance attenuation performance. The MPDT can be minimized while ensuring the existence of such a class of observer-based controllers for a given period of persistence. An example of DC-DC boost converter is provided to verify the effectiveness of theoretical findings.展开更多
This paper addresses a robust stabilization problem of a class of uncertain nonlinear systems using output measurements via a finite data-rate communication channel. The authors assumes that there exist an observer an...This paper addresses a robust stabilization problem of a class of uncertain nonlinear systems using output measurements via a finite data-rate communication channel. The authors assumes that there exist an observer and a control law for the systems in the absence of any finite data-rate communi- cation channel. Based on the observer and the control law, the authors constructs an encoder/decoder pair and provides a sufficient condition, including suitable sampling period and data rate, which will guarantee the stability of the closed-loop systems when a finite data-rate communication channel is introduced.展开更多
基金Heilongjiang Province Natural Science Foundation(Grant No.F2016019)；National Natural Science Foundation of China(Grant No.61571162)；Major National Science and Technology Project(2015ZX03004002004)； China Postdoctoral Science Foundation(Grant No.2014M561347).
文摘Cognitive radio is considered as an efficient way to improve the spectrum efficiency. As one of its key technologies,spectrum handoff can guarantee the transmission continuity of secondary users(SUs). In this paper,we address a new and more generalized spectrum handoff problem in cognitive radio networks(CRNs),by considering simultaneously energy efficiency,multiple spectrum handoffs and multiple channels. Furthermore,effects of the primary users'(PUs')arrival and service rate on the target channel sequence selection are also considered. In order to obtain the energy-efficient target channel sequence,we firstly analyze the energy consumption and the number of delivered bits per hertz in the spectrum handoff process,and formulate a ratio-type energy efficiency optimization problem,which can be transformed into a parametric problem by utilizing fractional programming. Then,we propose an algorithm combining dynamic programming with bisection(DPB)algorithm to solve the energy efficiency optimization problem. Our simulation results verify that the designed target channel sequence has better performance than the existing algorithms in terms of energy efficiency.
文摘The Port of Durban is one of the largest ports in the Southern Hemisphere and is the main port for the Southern African region. However, the port is reaching its capacity limit and it is apparent that for South Africa＇s economic growth this port needs to expand. In order to expand the port needs to not only expand its waterside infrastructure but it would need to provide new logistics corridors though the city of Durban. The city of Durban has completely surrounded the port making expansion options difficult and intertwined with the planning of the city. This paper examines the various options and timelines for port expansion as well as the issues from the city perspective. Areas of possible conflict in this process revolve around traffic capacity and related road/rail infrastructure, environmental issues, social and economic impacts.
文摘Based on the relationships between the lanes of signal-controlled intersections, we utilize the integration method of cluster analysis and stepwise regression and the integration method of cluster analysis and the principal component analysis method to predict the lanes＇ traffic volume of non-detector isolated controlled intersections. The results are examined by the real-time lanes＇ traffic volume data of the road network of Nanjing City. The problem of the lanes＇ traffic volume prediction of non-detector isolated signal-controlled intersections was resolved which can be widely used in urban traffic flow guidance and urban traffic control in cities.
基金supported by the National Natural Science Foundation of China(Grant No.61322301)the Natural Science Foundation of Heilongjiang(Grant Nos.F201417&JC2015015)+1 种基金the Fundamental Research Funds for the Central UniversitiesChina(Grant Nos.HIT.BRETIII.201211&HIT.BRETIV.201306)
文摘In this paper, the H∞ control problem is investigated for a class of discrete-time switched linear systems with modal persistent dwell-time(MPDT) switching. The redundant channels are considered to use in the data transmission to benefit the capability of overcoming the fragility of networks commonly configured by a single channel in the communication networks subject to random packet losses. In light of a new class of Lyapunov functions, the desired observer-based quasi-time-dependent controllers, which have less conservatism than the time-independent ones, are designed such that the resulting closed-loop system is exponentially mean-square stable with a guaranteed H_∞ disturbance attenuation performance. The MPDT can be minimized while ensuring the existence of such a class of observer-based controllers for a given period of persistence. An example of DC-DC boost converter is provided to verify the effectiveness of theoretical findings.
文摘This paper addresses a robust stabilization problem of a class of uncertain nonlinear systems using output measurements via a finite data-rate communication channel. The authors assumes that there exist an observer and a control law for the systems in the absence of any finite data-rate communi- cation channel. Based on the observer and the control law, the authors constructs an encoder/decoder pair and provides a sufficient condition, including suitable sampling period and data rate, which will guarantee the stability of the closed-loop systems when a finite data-rate communication channel is introduced.
