A new method was put forward to optimize the position of actuator/sensor of multi-body system with quick startup and brake. Dynamical equation was established for the system with intelligent structure of piezoelectric...A new method was put forward to optimize the position of actuator/sensor of multi-body system with quick startup and brake. Dynamical equation was established for the system with intelligent structure of piezoelectric actuators. According to the property of the modes varying with time, the performance index function was developed based on the optimal configuration principle of energy maximal dissipation, and the relevant optimal model was obtained. According to its characteristic, a float-encoding genetic algorithm, which is efficient, simple and excellent for solving the global-optimal solution of this problem, was adopted. Taking the plane manipulator as an example, the result of numerical calculation shows that, after the actuator/sensor position being optimized, the vibration amplitude of the multi-body system is reduced by 35% compared with that without optimization.展开更多
In wireless multimedia communications, it is extremely difficult to derive general end-to-end capacity results because of decentralized packet scheduling and the interference between communicating nodes. In this paper...In wireless multimedia communications, it is extremely difficult to derive general end-to-end capacity results because of decentralized packet scheduling and the interference between communicating nodes. In this paper, we present a state-based channel capacity perception scheme to provide statistical Quality-of-Service (QoS) guarantees under a medium or high traffic load for IEEE 802.11 wireless multi-hop networks. The proposed scheme first perceives the state of the wireless link from the MAC retransmission information and extends this information to calculate the wireless channel capacity, particularly under a saturated traffic load, on the basis of the interference among flows and the link state in the wireless multi-hop networks. Finally, the adaptive optimal control algorithm allocates a network resource and forwards the data packet by taking into consideration the channel capacity deployments in multi-terminal or multi-hop mesh networks. Extensive computer simulations demonstrate that the proposed scheme can achieve better performance in terms of packet delivery ratio and network throughput compared to the existing capacity prediction schemes.展开更多
The stability of the Newton-like algorithm in optimization flow control is considered in this paper. This algorithm is proved to be globally stable under a general network topology by means of Lyapunov stability theor...The stability of the Newton-like algorithm in optimization flow control is considered in this paper. This algorithm is proved to be globally stable under a general network topology by means of Lyapunov stability theory,without considering the round trip time of each source. While the stability of this algorithm with considering the round trip time is analyzed as well. The analysis shows that the algorithm with only one bottleneck link accessed by several sources is also globally stable,and all trajectories described by this algorithm ultimately converge to the equilibrium point.展开更多
A new medium access control method is proposed over the predominant Ethernet broadcast channel. Taking advantages of intrinsic variable length characteristic of standard Ethemet frame, message-oriented dynamic priorit...A new medium access control method is proposed over the predominant Ethernet broadcast channel. Taking advantages of intrinsic variable length characteristic of standard Ethemet frame, message-oriented dynamic priority mechanism is established. Prioritized medium access control operates under a so-called block mode in event of collisions. High priority messages have a chance to preempt block status incurred by low priority ones. By this means, the new MAC provides a conditional detrministic real time performance beyond a statistical one. Experiments effectiveness and attractiveness of the proposed scheme.Moreover,this new MAC is completely compatible with IEEE802.3 .展开更多
The techniques of stress relief mining in low-permeability coal seams and pillarless gob side retained roadway entry using Y-type ventilation and gas drainage systems were developed to control gas outbursts and applie...The techniques of stress relief mining in low-permeability coal seams and pillarless gob side retained roadway entry using Y-type ventilation and gas drainage systems were developed to control gas outbursts and applied successfully. However, as the mining depth increasing, parts of the gas drainage system are not suitable for mines with high gas emissions. Because larger mining depths cause higher ground stresses, it becomes extremely difficult to maintain long gob side roadways. The greater deformation suffered by the roadway is not favorable lor borehole drilling for continuous gas drainage. To solve these problems, Y-type ventilation and gas drainage systems installed from a roof roadway were designed for drainage optimization. This system was designed based on a gas-enrichment zone analysis developed from mining the 11-2 coal seam in the Zhuji Mine at Huainan, Anhui Province, China. The method of Y-type gas extraction from different mine areas was applied to the panel 1112（1） in the Zhuji Mine. The absolute gas emission rate was up to 116.3 m^3/min with an average flow of 69.1 m^3/min at an average drainage concentration of nearly 85 %. After the Y-type method was adopted, the concentration of gas in the return air was 0.15 %-0.64 %, averaging 0.39 % with a ventilation rate of 2100-2750 m^3/min. The gas management system proved to be efficient, and the effective gas control allowed safe production to continue .展开更多
Cognitive radio(CR) is regarded as a promising technology for providing a high spectral efficiency to mobile users by using heterogeneous wireless network architectures and dynamic spectrum access techniques.However,c...Cognitive radio(CR) is regarded as a promising technology for providing a high spectral efficiency to mobile users by using heterogeneous wireless network architectures and dynamic spectrum access techniques.However,cognitive radio networks(CRNs)may also impose some challenges due to the ever increasing complexity of network architecture,the increasing complexity with configuration and management of large-scale networks,fluctuating nature of the available spectrum,diverse Quality-of-Service(QoS)requirements of various applications,and the intensifying difficulties of centralized control,etc.Spectrum management functions with self-organization features can be used to address these challenges and realize this new network paradigm.In this paper,fundamentals of CR,including spectrum sensing,spectrum management,spectrum mobility and spectrum sharing,have been surveyed,with their paradigms of self-organization being emphasized.Variant aspects of selforganization paradigms in CRNs,including critical functionalities of Media Access Control(MAC)- and network-layer operations,are surveyed and compared.Furthermore,new directions and open problems in CRNs are also identified in this survey.展开更多
This paper discusses the problem of design and optimization of low-energy transfer orbit with multi-body environment. A new integrative method is proposed to effectively solve the problem, in which the parameterized p...This paper discusses the problem of design and optimization of low-energy transfer orbit with multi-body environment. A new integrative method is proposed to effectively solve the problem, in which the parameterized patched manifolds in CR3BP(circular restricted three-body problems), the shape-based method with multi-body environment, the homotopic method with multi-body environment, and the low-thrust capturing and descending algorithm with multi-body environment are all included. Firstly, the parameters describing the patched manifolds in CR3 BP are optimized until the least total absolute velocity increment has been got, including the employment of the shape-based method with multi-body environment. Secondly, the low-thrust control laws of the transfer orbit are optimized employing the homotopic method with multi-body environment that transfers the fuel optimization problem to an easier energy optimization problem. Thirdly, the low-thrust descending orbit around Mars is computed using the laws proposed in this paper. As a typical example, the Earth-Mars transfer orbit design is discussed. The results showed that the parameters describing the patched manifolds could be optimized by the DE(differential evolution) algorithm effectively; the homotopic method with multi-body environment could get the optimal value that meets the first order optimality conditions; and the low-thrust descending orbit could effectively be captured by Mars and finally become a circular parking orbit around it by the hypothesis control laws proposed in this paper. It shows that the final fuel cost is much less than the optimal transfer in the patched two-body problems. In conclusion, the method proposed in this paper could effectively solve the low-energy low-thrust optimal control problem in multi-body environment for the future deep space explorations.展开更多
基金Project(50390063) supported by the National Natural Science Foundation of China
文摘A new method was put forward to optimize the position of actuator/sensor of multi-body system with quick startup and brake. Dynamical equation was established for the system with intelligent structure of piezoelectric actuators. According to the property of the modes varying with time, the performance index function was developed based on the optimal configuration principle of energy maximal dissipation, and the relevant optimal model was obtained. According to its characteristic, a float-encoding genetic algorithm, which is efficient, simple and excellent for solving the global-optimal solution of this problem, was adopted. Taking the plane manipulator as an example, the result of numerical calculation shows that, after the actuator/sensor position being optimized, the vibration amplitude of the multi-body system is reduced by 35% compared with that without optimization.
基金supported by the National Natural Science Foundation of China under Grants No.60972038,No.61001077,No.61101105 the Scientific Research Foundation for Nanjing University of Posts and Telecommunications under Grant No.NY211007+2 种基金 the Open Research Fund of National Mobile Communications Research Laboratory,Southeast University under Grant No.2011D05 Specialized Research Fund for the Doctoral Program of Higher Education under Grant No.20113223120002 University Natural Science Research Project of Jiangsu Province under Grant No.11KJB510016
文摘In wireless multimedia communications, it is extremely difficult to derive general end-to-end capacity results because of decentralized packet scheduling and the interference between communicating nodes. In this paper, we present a state-based channel capacity perception scheme to provide statistical Quality-of-Service (QoS) guarantees under a medium or high traffic load for IEEE 802.11 wireless multi-hop networks. The proposed scheme first perceives the state of the wireless link from the MAC retransmission information and extends this information to calculate the wireless channel capacity, particularly under a saturated traffic load, on the basis of the interference among flows and the link state in the wireless multi-hop networks. Finally, the adaptive optimal control algorithm allocates a network resource and forwards the data packet by taking into consideration the channel capacity deployments in multi-terminal or multi-hop mesh networks. Extensive computer simulations demonstrate that the proposed scheme can achieve better performance in terms of packet delivery ratio and network throughput compared to the existing capacity prediction schemes.
基金the National Outstanding Youth Foundation of China (Grant No.60525303)the NNSF of China( Grant No.60404022 and 60604004)+2 种基金the NSF of Hebei Province (Grant No.102160)the Special Projects in Mathematics Funded by Natural Science Foundation of Hebei Prov-ince(Grant No.07M005)the NS of Education Office in Hebei Province (Grant No.2004123).
文摘The stability of the Newton-like algorithm in optimization flow control is considered in this paper. This algorithm is proved to be globally stable under a general network topology by means of Lyapunov stability theory,without considering the round trip time of each source. While the stability of this algorithm with considering the round trip time is analyzed as well. The analysis shows that the algorithm with only one bottleneck link accessed by several sources is also globally stable,and all trajectories described by this algorithm ultimately converge to the equilibrium point.
基金This workis partly supported by national 863 project under grant 2002 AA412010 08
文摘A new medium access control method is proposed over the predominant Ethernet broadcast channel. Taking advantages of intrinsic variable length characteristic of standard Ethemet frame, message-oriented dynamic priority mechanism is established. Prioritized medium access control operates under a so-called block mode in event of collisions. High priority messages have a chance to preempt block status incurred by low priority ones. By this means, the new MAC provides a conditional detrministic real time performance beyond a statistical one. Experiments effectiveness and attractiveness of the proposed scheme.Moreover,this new MAC is completely compatible with IEEE802.3 .
基金Acknowledgments This work was supported by the National Nat- ural Science Foundation of China （41172147）, the Anhui Province Science and Technology Research Plan （12010402110）, and the Shanxi Province One Hundred Distinguished Professor Plan project.
文摘The techniques of stress relief mining in low-permeability coal seams and pillarless gob side retained roadway entry using Y-type ventilation and gas drainage systems were developed to control gas outbursts and applied successfully. However, as the mining depth increasing, parts of the gas drainage system are not suitable for mines with high gas emissions. Because larger mining depths cause higher ground stresses, it becomes extremely difficult to maintain long gob side roadways. The greater deformation suffered by the roadway is not favorable lor borehole drilling for continuous gas drainage. To solve these problems, Y-type ventilation and gas drainage systems installed from a roof roadway were designed for drainage optimization. This system was designed based on a gas-enrichment zone analysis developed from mining the 11-2 coal seam in the Zhuji Mine at Huainan, Anhui Province, China. The method of Y-type gas extraction from different mine areas was applied to the panel 1112（1） in the Zhuji Mine. The absolute gas emission rate was up to 116.3 m^3/min with an average flow of 69.1 m^3/min at an average drainage concentration of nearly 85 %. After the Y-type method was adopted, the concentration of gas in the return air was 0.15 %-0.64 %, averaging 0.39 % with a ventilation rate of 2100-2750 m^3/min. The gas management system proved to be efficient, and the effective gas control allowed safe production to continue .
基金ACKNOWLEDGEMENT This work was supported by National Natural Science Foundation of China （No. 61172050）, Program for New Century Excellent Talents in University （NECT-12-0774）, the open research fund of National Mobile Communications Research Laboratory, Southeast University （No.2013D12）, the Foundation of Beijing Engineering and Technology Research Center for Convergence Networks and Ubiquitous Services. The corresponding author is Dr. Zhongshan Zhang.
文摘Cognitive radio(CR) is regarded as a promising technology for providing a high spectral efficiency to mobile users by using heterogeneous wireless network architectures and dynamic spectrum access techniques.However,cognitive radio networks(CRNs)may also impose some challenges due to the ever increasing complexity of network architecture,the increasing complexity with configuration and management of large-scale networks,fluctuating nature of the available spectrum,diverse Quality-of-Service(QoS)requirements of various applications,and the intensifying difficulties of centralized control,etc.Spectrum management functions with self-organization features can be used to address these challenges and realize this new network paradigm.In this paper,fundamentals of CR,including spectrum sensing,spectrum management,spectrum mobility and spectrum sharing,have been surveyed,with their paradigms of self-organization being emphasized.Variant aspects of selforganization paradigms in CRNs,including critical functionalities of Media Access Control(MAC)- and network-layer operations,are surveyed and compared.Furthermore,new directions and open problems in CRNs are also identified in this survey.
基金supported by the National Hi-Tech Research and Development Program of China("863"Project)(Grant No.2010AA7040014)
文摘This paper discusses the problem of design and optimization of low-energy transfer orbit with multi-body environment. A new integrative method is proposed to effectively solve the problem, in which the parameterized patched manifolds in CR3BP(circular restricted three-body problems), the shape-based method with multi-body environment, the homotopic method with multi-body environment, and the low-thrust capturing and descending algorithm with multi-body environment are all included. Firstly, the parameters describing the patched manifolds in CR3 BP are optimized until the least total absolute velocity increment has been got, including the employment of the shape-based method with multi-body environment. Secondly, the low-thrust control laws of the transfer orbit are optimized employing the homotopic method with multi-body environment that transfers the fuel optimization problem to an easier energy optimization problem. Thirdly, the low-thrust descending orbit around Mars is computed using the laws proposed in this paper. As a typical example, the Earth-Mars transfer orbit design is discussed. The results showed that the parameters describing the patched manifolds could be optimized by the DE(differential evolution) algorithm effectively; the homotopic method with multi-body environment could get the optimal value that meets the first order optimality conditions; and the low-thrust descending orbit could effectively be captured by Mars and finally become a circular parking orbit around it by the hypothesis control laws proposed in this paper. It shows that the final fuel cost is much less than the optimal transfer in the patched two-body problems. In conclusion, the method proposed in this paper could effectively solve the low-energy low-thrust optimal control problem in multi-body environment for the future deep space explorations.
