An energy-efficient heuristic mechanism is presented to obtain the optimal solution for the coverage problem in sensor networks. The mechanism can ensure that all targets are fully covered corresponding to their level...An energy-efficient heuristic mechanism is presented to obtain the optimal solution for the coverage problem in sensor networks. The mechanism can ensure that all targets are fully covered corresponding to their levels of importance at minimum cost, and the ant colony optimization algorithm （ACO） is adopted to achieve the above metrics. Based on the novel design of heuristic factors, artificial ants can adaptively detect the energy status and coverage ability of sensor networks via local information. By introducing the evaluation function to global pheromone updating rule, the pheromone trail on the best solution is greatly enhanced, so that the convergence process of the algorithm is speed up. Finally, the optimal solution with a higher coverage- efficiency and a longer lifetime is obtained.展开更多
A heuristic metric is presented to achieve the optimal connected set covering problem （SCP） in sensor networks. The coverage solution with the energy efficiency can guarantee that all targets are fully covered. Amon...A heuristic metric is presented to achieve the optimal connected set covering problem （SCP） in sensor networks. The coverage solution with the energy efficiency can guarantee that all targets are fully covered. Among targets, the crucial ones are redundantly covered to ensure more reliable monitors. And the information collected by the above coverage solution can be transmitted to Sink by the connected data-gathering structure. A novel ant colony optimization （ACO） algorithm--improved-MMAS-ACS-hybrid algorithm （IMAH） is adopted to achieve the above metric. Based on the design of the heuristic factor, artificial ants can adaptively detect the coverage and energy status of sensor networks and find the low-energy-cost paths to keep the communication connectivity to Sink. By introducing the pheromone-judgment-factor and the evaluation function to the pheromone updating rule, the pheromone trail on the global-best solution is enhanced, while avoiding the premature stagnation. Finally, the energy efficiency set can be obtained with high coverage-efficiency to all targets and reliable connectivity to Sink and the lifetime of the connected coverage set is prolonged.展开更多
A novel immune-swarm intelligence (ISI) based algorithm for solving the deterministic coverage problems of wireless sensor networks was presented.It makes full use of information sharing and retains diversity from the...A novel immune-swarm intelligence (ISI) based algorithm for solving the deterministic coverage problems of wireless sensor networks was presented.It makes full use of information sharing and retains diversity from the principle of particle swarm optimization (PSO) and artificial immune system (AIS).The algorithm was analyzed in detail and proper swarm size,evolving generations,gene-exchange individual order,and gene-exchange proportion in molecule were obtained for better algorithm performances.According to the test results,the appropriate parameters are about 50 swarm individuals,over 3 000 evolving generations,20%-25% gene-exchange proportion in molecule with gene-exchange taking place between better fitness affinity individuals.The algorithm is practical and effective in maximizing the coverage probability with given number of sensors and minimizing sensor numbers with required coverage probability in sensor placement.It can reach a better result quickly,especially with the proper calculation parameters.展开更多
With the （ k, n ）-threshold scheme of secret sharing in the field of information security technology as an application background, the concept of set （ k, n ）-exact cover is presented in this paper. It is a modifi...With the （ k, n ）-threshold scheme of secret sharing in the field of information security technology as an application background, the concept of set （ k, n ）-exact cover is presented in this paper. It is a modification of the original concept of set covering problem. It is also different from the concept of exact cover defined by J.E. Hopcmft. Some properties of （k, n ） -exact cover are investigated; a sufficient condition for a set to be （ k, n ） -exactly coverable is given. It follows that a feasible assignment scheme of a set for the （ k, n） -exact eover is obtained if this set satisfies the sufficient condition.展开更多
This paper presents a passive monitoring mechanism, loss）, nodes inference （LoNI）, to identify loss）, nodes in wireless sensor network using end-to-end application traffic. Given topology dynamics and bandwidth co...This paper presents a passive monitoring mechanism, loss）, nodes inference （LoNI）, to identify loss）, nodes in wireless sensor network using end-to-end application traffic. Given topology dynamics and bandwidth constraints, a space-efficient packet marking scheme is first introduced. The scheme uses a Bloom filter as a compression tool so that path information can bc piggybacked by data packets. Based on the path information, LoNI then adopts a fast algorithm to detect lossy nodes. The algorithm formulates the inference problem as a weighted set-cover problem and solves it using a greedy approach with low complexity. Simulations show that LoNI can locate about 80% of lossy nodes when lossy nodes are rare in the network. Furthermore, LoNI performs better for the lossy nodes near the sink or with higher loss rates.展开更多
This paper introduces the general process of the search algorithm Structure through the knight problem. According to the characteristics of the problem, we detailed discuss the DFS（Depth First Search） algorithm and ...This paper introduces the general process of the search algorithm Structure through the knight problem. According to the characteristics of the problem, we detailed discuss the DFS（Depth First Search） algorithm and BFS（Breadth First Search） algorithm, and combine the two algorithms together to solve the knights coverage problem. This article has a good reference for the mixed-use scenarios which requires a variety of search algorithms.展开更多
The number of scientific investigations on women＇s football specific to the topics of player characteristics and demands of the game has considerably increased in recent years due to the increased popularity of the w...The number of scientific investigations on women＇s football specific to the topics of player characteristics and demands of the game has considerably increased in recent years due to the increased popularity of the women＇s game worldwide, although they are not yet as numerous as in the case of men＇s football. To date, only two scientific publications have attempted to review the main findings of studies published in this area. However, one of them was published about 20 years ago, when women＇s football was still in its infancy and there were only a few studies to report on. The other review was more recent. Nonetheless, its main focus was on the game and training demands of senior elite female players. Thus, information on female footballers of lower competitive levels and younger age groups was not included. Consequently, an updated review is needed in this area. The present article therefore aims to provide an overview of a series of studies that have been published so far on the specific characteristics of female football players and the demands of match-play. Mean values reported in the literature for age （12-27 years）, body height （155-174 cm）, body mass （48-72 kg）, percent body fat （13%-29%）, maximal oxygen uptake （45.1-55.5 mL/kg/min）, Yo-Yo Intermittent Recovery Test Level l （780-1379 m）, maximum heart rate （189-202 bpm）, 30 m sprint times （4.34-4.96 s）, and counter- movement jump or vertical jump （28-50 cm） vary mostly according to the players＇ competitive level and positional role. There are also some special considerations that coaches and other practitioners should he aware of when working with female athletes such as the menstrual cycle, potential pregnancy and lactation, common injury risks （particularly knee and head injuries） and health concerns （e.g., female athlete triad, iron deficiency, and anemia） that may affect players＇ football performance, health or return to play. Reported mean values for total distance covered （4-13 km）, distance covered at high-speed （0.2-1.7 km）, average/peak heart rate （74%-87%/94%-99% HRmax）, average/peak oxygen uptake （52%-77%/96%-98% VO2max）, and blood lactate （2.2-7.3 mmol/L） during women＇s football match-play vary according to the players＇ competitive level and positional role. Methodological differences may account for the discrepancy of the reported values as well. Finally, this review also aims to identify literature gaps that require further scientific research in women＇s football and to derive a few practical recom-mendations. The information presented in this report provides an objective point of reference about player characteristics and game demands at various levels of women＇s football, which can help coaches and sport scientists to design more effective training programs and science-based strategies for the further improvement of players＇ football performance, health, game standards, and positive image of this sport.展开更多
This article discusses the status of the ecological environment in Heihe River water source district, and points out that the decline of the forest coverage, the degradation of the pasture and the shrinking back of th...This article discusses the status of the ecological environment in Heihe River water source district, and points out that the decline of the forest coverage, the degradation of the pasture and the shrinking back of the glacier, the increased soil erosion and other phenomena are the main ecological and environmental problems in this area. The main reason is the natural and man-made results. This article proposes the specific measures to protect the ecological environment in Heihe River water source district.展开更多
基金The Natural Science Foundation of Jiangsu Province(NoBK2005409)
文摘An energy-efficient heuristic mechanism is presented to obtain the optimal solution for the coverage problem in sensor networks. The mechanism can ensure that all targets are fully covered corresponding to their levels of importance at minimum cost, and the ant colony optimization algorithm （ACO） is adopted to achieve the above metrics. Based on the novel design of heuristic factors, artificial ants can adaptively detect the energy status and coverage ability of sensor networks via local information. By introducing the evaluation function to global pheromone updating rule, the pheromone trail on the best solution is greatly enhanced, so that the convergence process of the algorithm is speed up. Finally, the optimal solution with a higher coverage- efficiency and a longer lifetime is obtained.
文摘A heuristic metric is presented to achieve the optimal connected set covering problem （SCP） in sensor networks. The coverage solution with the energy efficiency can guarantee that all targets are fully covered. Among targets, the crucial ones are redundantly covered to ensure more reliable monitors. And the information collected by the above coverage solution can be transmitted to Sink by the connected data-gathering structure. A novel ant colony optimization （ACO） algorithm--improved-MMAS-ACS-hybrid algorithm （IMAH） is adopted to achieve the above metric. Based on the design of the heuristic factor, artificial ants can adaptively detect the coverage and energy status of sensor networks and find the low-energy-cost paths to keep the communication connectivity to Sink. By introducing the pheromone-judgment-factor and the evaluation function to the pheromone updating rule, the pheromone trail on the global-best solution is enhanced, while avoiding the premature stagnation. Finally, the energy efficiency set can be obtained with high coverage-efficiency to all targets and reliable connectivity to Sink and the lifetime of the connected coverage set is prolonged.
基金Project(2008BA00400)supported by the Foundation of Department of Science and Technology of Jiangxi Province,China
文摘A novel immune-swarm intelligence (ISI) based algorithm for solving the deterministic coverage problems of wireless sensor networks was presented.It makes full use of information sharing and retains diversity from the principle of particle swarm optimization (PSO) and artificial immune system (AIS).The algorithm was analyzed in detail and proper swarm size,evolving generations,gene-exchange individual order,and gene-exchange proportion in molecule were obtained for better algorithm performances.According to the test results,the appropriate parameters are about 50 swarm individuals,over 3 000 evolving generations,20%-25% gene-exchange proportion in molecule with gene-exchange taking place between better fitness affinity individuals.The algorithm is practical and effective in maximizing the coverage probability with given number of sensors and minimizing sensor numbers with required coverage probability in sensor placement.It can reach a better result quickly,especially with the proper calculation parameters.
基金Supported by the National Natural Science Foundation of China (No. 60673053 90718011 )
文摘With the （ k, n ）-threshold scheme of secret sharing in the field of information security technology as an application background, the concept of set （ k, n ）-exact cover is presented in this paper. It is a modification of the original concept of set covering problem. It is also different from the concept of exact cover defined by J.E. Hopcmft. Some properties of （k, n ） -exact cover are investigated; a sufficient condition for a set to be （ k, n ） -exactly coverable is given. It follows that a feasible assignment scheme of a set for the （ k, n） -exact eover is obtained if this set satisfies the sufficient condition.
文摘This paper presents a passive monitoring mechanism, loss）, nodes inference （LoNI）, to identify loss）, nodes in wireless sensor network using end-to-end application traffic. Given topology dynamics and bandwidth constraints, a space-efficient packet marking scheme is first introduced. The scheme uses a Bloom filter as a compression tool so that path information can bc piggybacked by data packets. Based on the path information, LoNI then adopts a fast algorithm to detect lossy nodes. The algorithm formulates the inference problem as a weighted set-cover problem and solves it using a greedy approach with low complexity. Simulations show that LoNI can locate about 80% of lossy nodes when lossy nodes are rare in the network. Furthermore, LoNI performs better for the lossy nodes near the sink or with higher loss rates.
文摘This paper introduces the general process of the search algorithm Structure through the knight problem. According to the characteristics of the problem, we detailed discuss the DFS（Depth First Search） algorithm and BFS（Breadth First Search） algorithm, and combine the two algorithms together to solve the knights coverage problem. This article has a good reference for the mixed-use scenarios which requires a variety of search algorithms.
文摘The number of scientific investigations on women＇s football specific to the topics of player characteristics and demands of the game has considerably increased in recent years due to the increased popularity of the women＇s game worldwide, although they are not yet as numerous as in the case of men＇s football. To date, only two scientific publications have attempted to review the main findings of studies published in this area. However, one of them was published about 20 years ago, when women＇s football was still in its infancy and there were only a few studies to report on. The other review was more recent. Nonetheless, its main focus was on the game and training demands of senior elite female players. Thus, information on female footballers of lower competitive levels and younger age groups was not included. Consequently, an updated review is needed in this area. The present article therefore aims to provide an overview of a series of studies that have been published so far on the specific characteristics of female football players and the demands of match-play. Mean values reported in the literature for age （12-27 years）, body height （155-174 cm）, body mass （48-72 kg）, percent body fat （13%-29%）, maximal oxygen uptake （45.1-55.5 mL/kg/min）, Yo-Yo Intermittent Recovery Test Level l （780-1379 m）, maximum heart rate （189-202 bpm）, 30 m sprint times （4.34-4.96 s）, and counter- movement jump or vertical jump （28-50 cm） vary mostly according to the players＇ competitive level and positional role. There are also some special considerations that coaches and other practitioners should he aware of when working with female athletes such as the menstrual cycle, potential pregnancy and lactation, common injury risks （particularly knee and head injuries） and health concerns （e.g., female athlete triad, iron deficiency, and anemia） that may affect players＇ football performance, health or return to play. Reported mean values for total distance covered （4-13 km）, distance covered at high-speed （0.2-1.7 km）, average/peak heart rate （74%-87%/94%-99% HRmax）, average/peak oxygen uptake （52%-77%/96%-98% VO2max）, and blood lactate （2.2-7.3 mmol/L） during women＇s football match-play vary according to the players＇ competitive level and positional role. Methodological differences may account for the discrepancy of the reported values as well. Finally, this review also aims to identify literature gaps that require further scientific research in women＇s football and to derive a few practical recom-mendations. The information presented in this report provides an objective point of reference about player characteristics and game demands at various levels of women＇s football, which can help coaches and sport scientists to design more effective training programs and science-based strategies for the further improvement of players＇ football performance, health, game standards, and positive image of this sport.
文摘This article discusses the status of the ecological environment in Heihe River water source district, and points out that the decline of the forest coverage, the degradation of the pasture and the shrinking back of the glacier, the increased soil erosion and other phenomena are the main ecological and environmental problems in this area. The main reason is the natural and man-made results. This article proposes the specific measures to protect the ecological environment in Heihe River water source district.
