美国纽柯钢铁公司(Nucor Corporation)宣布,其已与Next Era Energy Resources(直译“下一代能源”,下称NextEra)达成一项重要的可再生能源合作协议。据悉,该公司将从NextEra的Sebree Solar太阳能项目购买250兆瓦的可再生能源,以支持其...美国纽柯钢铁公司(Nucor Corporation)宣布,其已与Next Era Energy Resources(直译“下一代能源”,下称NextEra)达成一项重要的可再生能源合作协议。据悉,该公司将从NextEra的Sebree Solar太阳能项目购买250兆瓦的可再生能源,以支持其在美国肯塔基州(Kentucky)的生产活动。展开更多
Since most ad hoc mobile devices today operate on batteries,the power consumption becomes an important issue.This paper proposes a cross-layer design of energy-aware ad hoc on-demand distance vector(CEAODV) routing pr...Since most ad hoc mobile devices today operate on batteries,the power consumption becomes an important issue.This paper proposes a cross-layer design of energy-aware ad hoc on-demand distance vector(CEAODV) routing protocol which adopts cross-layer mechanism and energy-aware metric to improve AODV routing protocol to reduce the energy consumption and then prolong the life of the whole network.In CEAODV,the link layer and the routing layer work together to choose the optimized transmission power for nodes and the route for packets.The link layer provides the energy consumption information for the routing layer and the routing layer chooses route accordingly and conversely controls the link layer to adjust the transmission power.The simulation result shows that CEAODV can outperform AODV to save more energy.It can reduce the consumed energy by about 8%over traditional energy-aware algorithm.And the performance is better when the traffic load is higher in the network.展开更多
A new Network Coding mechanism in WSNs(Wireless Sensor Networks), which is named COEQ and aims at balancing coding opportunities, energy and QoS, is proposed and analyzed. Implemented on the basis of traditional AODV ...A new Network Coding mechanism in WSNs(Wireless Sensor Networks), which is named COEQ and aims at balancing coding opportunities, energy and QoS, is proposed and analyzed. Implemented on the basis of traditional AODV protocol, COEQ evaluates several metrics of paths comprehensively with TOPSIS method including minimum remaining energy, coding opportunities, QoS and so on, so as to select the optimal transmitting route. Experiments on NS[2] show that COEQ can improve throughput and save energy when the transmitting rate is low.展开更多
Wireless sensor networks (WSNs) are important application for safety monitoring in underground coal mines, which are difficult to monitor due to natural conditions. Based on the characteristic of limited energy for WS...Wireless sensor networks (WSNs) are important application for safety monitoring in underground coal mines, which are difficult to monitor due to natural conditions. Based on the characteristic of limited energy for WSNs in confined underground area such as coal face and laneway, we presents an energy- efficient clustering routing protocol based on weight (ECRPW) to prolong the lifetime of networks. ECRPW takes into consideration the nodes' residual energy during the election process of cluster heads. The constraint of distance threshold is used to optimize cluster scheme. Furthermore, the protocol also sets up a routing tree based on cluster heads' weight. The results show that ECRPW had better perfor- mance in energy consumption, death ratio of node and network lifetime.展开更多
With the advent of the era of cloud computing, the high energy consumption of cloud computing data centers has become a prominent problem, and how to reduce the energy consumption of cloud computing data center and im...With the advent of the era of cloud computing, the high energy consumption of cloud computing data centers has become a prominent problem, and how to reduce the energy consumption of cloud computing data center and improve the efficiency of data center has become the research focus of researchers all the world. In a cloud environment, virtual machine consolidation(VMC) is an effective strategy that can improve the energy efficiency. However, at the same time, in the process of virtual machine consolidation, we need to deal with the tradeoff between energy consumption and excellent service performance to meet service level agreement(SLA). In this paper, we propose a new virtual machine consolidation framework for achieving better energy efficiency-Improved Underloaded Decision(IUD) algorithm and Minimum Average Utilization Difference(MAUD) algorithm. Finally, based on real workload data on Planet Lab, experiments have been done with the cloud simulation platform Cloud Sim. The experimental result shows that the proposed algorithm can reduce the energy consumption and SLA violation of data centers compared with existing algorithms, improving the energy efficiency of data centers.展开更多
In this paper, the outage perfor- mance of a cognitive relaying network over Nakagami-m fading channels, employing simultaneous wireless information and power transfer （SWIPT） technology is analyzed and evaluated. T...In this paper, the outage perfor- mance of a cognitive relaying network over Nakagami-m fading channels, employing simultaneous wireless information and power transfer （SWIPT） technology is analyzed and evaluated. The operation of this network is considered in conjunction with the convention- al decode-and-forward （DF） and incremental DF （IDF） protocols. For the conventional DF protocol, it is assumed that there is no direct link between the secondary transmitter （S） and the secondary destination （D）, while （for both protocols） after harvesting energy, the relay node （R） always helps to forward the resulting signal to D. However, for the IDF protocol, R assists in relaying S＇s information to D only when the direct communication between S and D has failed. Furthermore, for both DF and IDF protocols, we assume there is no power supply for R, and R harvests energy from the transmitted signal of S. We derive exact ana- lytical expressions for the outage probability at D in DF and IDF protocols, respectively, in terms of the bivariate Meijer＇s G-function. Performance evaluation results obtained by means of Monte-Carlo simulations are also provided and have validated the correctness of the oroDosed analysis.展开更多
Energy efficiency is a primary consideration in a wireless sensor network (WSN). This is also a major parameter when designing a medium access control (MAC) protocol for WSNs. Hierarchical clustering structure is rega...Energy efficiency is a primary consideration in a wireless sensor network (WSN). This is also a major parameter when designing a medium access control (MAC) protocol for WSNs. Hierarchical clustering structure is regarded suitable for WSNs due to its good performance in energy conservation. In this work, an adequately flexible mechanism for clustering WSNs is designed, in which some creative or promotional metrics are utilized, such as cluster head selection algorithm, cluster optional reconstruction, interested data transmission, multiple path routing protocol. All these strategies were cooperated to maximize energy saving of whole system. An appropriate MAC protocol for this mechanism is proposed, by flexibly switching the status of diverse sensor nodes in different strategies. The simulation results show that the proposed MAC protocol is suitable for clustering WSNs and performs well in aspects of energy efficiency, flexibility and scalability.展开更多
Canada is abundant in oil sands. The most present statistics indicates that Canada owns the proven reserves of oil sands as much as 175 billion barrels and is producing oil from sands at the rate of over 100 million b...Canada is abundant in oil sands. The most present statistics indicates that Canada owns the proven reserves of oil sands as much as 175 billion barrels and is producing oil from sands at the rate of over 100 million barrel/day. Boosted by surging international oil price, large-scale development of oil sands in Canada attracts more and more attention from the industry. During the past two years, several Chinese oil giants had also invested in Canada＇s energy sector, promoting the Sino- Canada energy cooperation into a new stage. Therefore, it is safe to conclude that the energy cooperation between the two countries has good foundation and brilliant future.展开更多
China National Petroleum Corporation （CNPC） and KazMunaiGaz National Co, Kazakhstan＇s national oil company, signed an agreement on construction and operation of the Phase Ⅱ of the China-Kazakhstan in Astana, the c...China National Petroleum Corporation （CNPC） and KazMunaiGaz National Co, Kazakhstan＇s national oil company, signed an agreement on construction and operation of the Phase Ⅱ of the China-Kazakhstan in Astana, the capital of Kazakhstan, on August 18. The signature was witnessed by Chinese President Hu Jintao and his Kazak counterpart Nursultan Nazarbayev.展开更多
In the wireless sensor networks, high efficient data routing for the limited energy resource networks is an important issue. By introducing Antcolony algorithm, this paper proposes the wireless sensor network routing ...In the wireless sensor networks, high efficient data routing for the limited energy resource networks is an important issue. By introducing Antcolony algorithm, this paper proposes the wireless sensor network routing algorithm based on LEACH. During the construction of sensor network clusters, to avoid the node premature death because of the energy consumption, only the nodes whose residual energy is higher than the average energy can be chosen as the cluster heads. The method of repeated division is used to divide the clusters in sensor networks so that the numbers of the nodes in each cluster are balanced. The basic thought of ant-colony algorithm is adopted to realize the data routing between the cluster heads and sink nodes, and the maintenance of routing. The analysis and simulation showed that the proposed routing protocol not only can reduce the energy consumption, balance the energy consumption between nodes, but also prolong the network lifetime.展开更多
The network coding is a new technology in the field of information in 21st century. It could enhance the network throughput and save the energy consumption, and is mainly based on the single transmission rate. However...The network coding is a new technology in the field of information in 21st century. It could enhance the network throughput and save the energy consumption, and is mainly based on the single transmission rate. However, with the development of wireless network and equipment, wireless local network MAC protocols have already supported the multi-rate transmission. This paper investigates the optimal relay selection problem based on network coding. Firstly, the problem is formulated as an optimization problem. Moreover, a relay algorithm based on network coding is proposed and the transmission time gain of our algorithm over the traditional relay algorithm is analyzed. Lastly, we compare total transmission time and the energy consumption of our proposed algorithm, Network Coding with Relay Assistance (NCRA), Transmission Request (TR), and the Direct Transmission (DT) without relay algorithm by adopting IEEE 802.11b. The simulation results demonstrate that our algorithm that improves the coding opportunity by the cooperation of the relay nodes leads to the transmission time decrease of up to 17% over the traditional relay algorithms.展开更多
Wireless Body Area Network(WBAN) is the most promising technology in e-health applications.Energy efficiency stands out as the paramount issue for WBAN.In this paper,an energy efficient MAC protocol named Quasi-Sleep-...Wireless Body Area Network(WBAN) is the most promising technology in e-health applications.Energy efficiency stands out as the paramount issue for WBAN.In this paper,an energy efficient MAC protocol named Quasi-Sleep-Preempt-Supported(QSPS) is proposed.The protocol is mainly TDMA-based:nodes transmit packets in the allocated slots,while entering the Q-Sleep mode in other slots.Moreover,for a node with emergency packet,it can broadcast a special designed Awakening Message to wake up the whole network and preempts the right to use the current slot to transmit that emergency packet,thus decreasing delay.Compared with relevant protocols,QS-PS can achieve high energy efficiency and decrease the delay of both normal packets and emergency packets.展开更多
文摘美国纽柯钢铁公司(Nucor Corporation)宣布,其已与Next Era Energy Resources(直译“下一代能源”,下称NextEra)达成一项重要的可再生能源合作协议。据悉,该公司将从NextEra的Sebree Solar太阳能项目购买250兆瓦的可再生能源,以支持其在美国肯塔基州(Kentucky)的生产活动。
基金Supported by National Natural Science Foundation of China(No.90604013)Natural Science Foundation of Tianjin(No.08JCYBJC14200)National High Technology Research and Development Program("863"Program)of China(No.2007AA01Z220)
文摘Since most ad hoc mobile devices today operate on batteries,the power consumption becomes an important issue.This paper proposes a cross-layer design of energy-aware ad hoc on-demand distance vector(CEAODV) routing protocol which adopts cross-layer mechanism and energy-aware metric to improve AODV routing protocol to reduce the energy consumption and then prolong the life of the whole network.In CEAODV,the link layer and the routing layer work together to choose the optimized transmission power for nodes and the route for packets.The link layer provides the energy consumption information for the routing layer and the routing layer chooses route accordingly and conversely controls the link layer to adjust the transmission power.The simulation result shows that CEAODV can outperform AODV to save more energy.It can reduce the consumed energy by about 8%over traditional energy-aware algorithm.And the performance is better when the traffic load is higher in the network.
基金supported by the Chinese National Natural Science Foundation(No:61070204,61101108)Funding Project for Academic Human Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipality(11530500015)
文摘A new Network Coding mechanism in WSNs(Wireless Sensor Networks), which is named COEQ and aims at balancing coding opportunities, energy and QoS, is proposed and analyzed. Implemented on the basis of traditional AODV protocol, COEQ evaluates several metrics of paths comprehensively with TOPSIS method including minimum remaining energy, coding opportunities, QoS and so on, so as to select the optimal transmitting route. Experiments on NS[2] show that COEQ can improve throughput and save energy when the transmitting rate is low.
基金supports provided by the National Natural Science Foundation of China (No.50904070)the China Postdoctoral Science Foundation (No.20100471009)+2 种基金the National High Technology Research and Development Program of China (Nos. 2008AA062200 and2007AA01Z180)the Key Project of Jiangsu (No. BG2007012)the Science Foundation of China University of Mining and Technology (No. OC080303)
文摘Wireless sensor networks (WSNs) are important application for safety monitoring in underground coal mines, which are difficult to monitor due to natural conditions. Based on the characteristic of limited energy for WSNs in confined underground area such as coal face and laneway, we presents an energy- efficient clustering routing protocol based on weight (ECRPW) to prolong the lifetime of networks. ECRPW takes into consideration the nodes' residual energy during the election process of cluster heads. The constraint of distance threshold is used to optimize cluster scheme. Furthermore, the protocol also sets up a routing tree based on cluster heads' weight. The results show that ECRPW had better perfor- mance in energy consumption, death ratio of node and network lifetime.
基金supported by the National Natural Science Foundation of China (NSFC) (No. 61272200, 10805019)the Program for Excellent Young Teachers in Higher Education of Guangdong, China (No. Yq2013012)+2 种基金the Fundamental Research Funds for the Central Universities (2015ZJ010)the Special Support Program of Guangdong Province (201528004)the Pearl River Science & Technology Star Project (201610010046)
文摘With the advent of the era of cloud computing, the high energy consumption of cloud computing data centers has become a prominent problem, and how to reduce the energy consumption of cloud computing data center and improve the efficiency of data center has become the research focus of researchers all the world. In a cloud environment, virtual machine consolidation(VMC) is an effective strategy that can improve the energy efficiency. However, at the same time, in the process of virtual machine consolidation, we need to deal with the tradeoff between energy consumption and excellent service performance to meet service level agreement(SLA). In this paper, we propose a new virtual machine consolidation framework for achieving better energy efficiency-Improved Underloaded Decision(IUD) algorithm and Minimum Average Utilization Difference(MAUD) algorithm. Finally, based on real workload data on Planet Lab, experiments have been done with the cloud simulation platform Cloud Sim. The experimental result shows that the proposed algorithm can reduce the energy consumption and SLA violation of data centers compared with existing algorithms, improving the energy efficiency of data centers.
基金supported in part by the National Natural Science Foundation of China(Grant No.61472343)China Postdoctoral Science Foundation(Grant No.2014M56074)
文摘In this paper, the outage perfor- mance of a cognitive relaying network over Nakagami-m fading channels, employing simultaneous wireless information and power transfer （SWIPT） technology is analyzed and evaluated. The operation of this network is considered in conjunction with the convention- al decode-and-forward （DF） and incremental DF （IDF） protocols. For the conventional DF protocol, it is assumed that there is no direct link between the secondary transmitter （S） and the secondary destination （D）, while （for both protocols） after harvesting energy, the relay node （R） always helps to forward the resulting signal to D. However, for the IDF protocol, R assists in relaying S＇s information to D only when the direct communication between S and D has failed. Furthermore, for both DF and IDF protocols, we assume there is no power supply for R, and R harvests energy from the transmitted signal of S. We derive exact ana- lytical expressions for the outage probability at D in DF and IDF protocols, respectively, in terms of the bivariate Meijer＇s G-function. Performance evaluation results obtained by means of Monte-Carlo simulations are also provided and have validated the correctness of the oroDosed analysis.
文摘Energy efficiency is a primary consideration in a wireless sensor network (WSN). This is also a major parameter when designing a medium access control (MAC) protocol for WSNs. Hierarchical clustering structure is regarded suitable for WSNs due to its good performance in energy conservation. In this work, an adequately flexible mechanism for clustering WSNs is designed, in which some creative or promotional metrics are utilized, such as cluster head selection algorithm, cluster optional reconstruction, interested data transmission, multiple path routing protocol. All these strategies were cooperated to maximize energy saving of whole system. An appropriate MAC protocol for this mechanism is proposed, by flexibly switching the status of diverse sensor nodes in different strategies. The simulation results show that the proposed MAC protocol is suitable for clustering WSNs and performs well in aspects of energy efficiency, flexibility and scalability.
文摘Canada is abundant in oil sands. The most present statistics indicates that Canada owns the proven reserves of oil sands as much as 175 billion barrels and is producing oil from sands at the rate of over 100 million barrel/day. Boosted by surging international oil price, large-scale development of oil sands in Canada attracts more and more attention from the industry. During the past two years, several Chinese oil giants had also invested in Canada＇s energy sector, promoting the Sino- Canada energy cooperation into a new stage. Therefore, it is safe to conclude that the energy cooperation between the two countries has good foundation and brilliant future.
文摘China National Petroleum Corporation （CNPC） and KazMunaiGaz National Co, Kazakhstan＇s national oil company, signed an agreement on construction and operation of the Phase Ⅱ of the China-Kazakhstan in Astana, the capital of Kazakhstan, on August 18. The signature was witnessed by Chinese President Hu Jintao and his Kazak counterpart Nursultan Nazarbayev.
基金Acknowledgements Supported by the Fundamental Research Funds for the Central Universities（72104988）, The National High Technology Research and Development Program of China （ 2009AA01 Z204, 2007AA01Z429, 2007AA01Z405）, The post doctor science foundation of China （20090451495, 20090461415） The National Natural science foundation of China （60874085, 60633020, 60803151 ）, The Natural Science Basic Research Plan in Shaanxi Province of China （Program No. SJ08F13）, The Aviation Sci- ence Foundation of China （2007ZD31003, 2008ZD31001 ）
文摘In the wireless sensor networks, high efficient data routing for the limited energy resource networks is an important issue. By introducing Antcolony algorithm, this paper proposes the wireless sensor network routing algorithm based on LEACH. During the construction of sensor network clusters, to avoid the node premature death because of the energy consumption, only the nodes whose residual energy is higher than the average energy can be chosen as the cluster heads. The method of repeated division is used to divide the clusters in sensor networks so that the numbers of the nodes in each cluster are balanced. The basic thought of ant-colony algorithm is adopted to realize the data routing between the cluster heads and sink nodes, and the maintenance of routing. The analysis and simulation showed that the proposed routing protocol not only can reduce the energy consumption, balance the energy consumption between nodes, but also prolong the network lifetime.
基金Supported by Anhui Natural Science Foundation, China(No.1308085MF87, 128085MF89)Open Fund of State Key Laboratory for Novel Software Technology,Nanjing University,China (No.KFKT2011B18)Hefei University of Technology Ph.D. Foundation (No.2010HGBZ-0552)
文摘The network coding is a new technology in the field of information in 21st century. It could enhance the network throughput and save the energy consumption, and is mainly based on the single transmission rate. However, with the development of wireless network and equipment, wireless local network MAC protocols have already supported the multi-rate transmission. This paper investigates the optimal relay selection problem based on network coding. Firstly, the problem is formulated as an optimization problem. Moreover, a relay algorithm based on network coding is proposed and the transmission time gain of our algorithm over the traditional relay algorithm is analyzed. Lastly, we compare total transmission time and the energy consumption of our proposed algorithm, Network Coding with Relay Assistance (NCRA), Transmission Request (TR), and the Direct Transmission (DT) without relay algorithm by adopting IEEE 802.11b. The simulation results demonstrate that our algorithm that improves the coding opportunity by the cooperation of the relay nodes leads to the transmission time decrease of up to 17% over the traditional relay algorithms.
基金supported in part by National Natural Science Foundation of China(NSFC,No.61325012,6171219,6122001,61202373)
文摘Wireless Body Area Network(WBAN) is the most promising technology in e-health applications.Energy efficiency stands out as the paramount issue for WBAN.In this paper,an energy efficient MAC protocol named Quasi-Sleep-Preempt-Supported(QSPS) is proposed.The protocol is mainly TDMA-based:nodes transmit packets in the allocated slots,while entering the Q-Sleep mode in other slots.Moreover,for a node with emergency packet,it can broadcast a special designed Awakening Message to wake up the whole network and preempts the right to use the current slot to transmit that emergency packet,thus decreasing delay.Compared with relevant protocols,QS-PS can achieve high energy efficiency and decrease the delay of both normal packets and emergency packets.
