One of the key challenges in ad-hoc networks is the resource discovery problem.How efciently&quickly the queried resource/object can be resolved in such a highly dynamic self-evolving network is the underlying que...One of the key challenges in ad-hoc networks is the resource discovery problem.How efciently&quickly the queried resource/object can be resolved in such a highly dynamic self-evolving network is the underlying question?Broadcasting is a basic technique in the Mobile Ad-hoc Networks(MANETs),and it refers to sending a packet from one node to every other node within the transmission range.Flooding is a type of broadcast where the received packet is retransmitted once by every node.The naive ooding technique oods the network with query messages,while the random walk scheme operates by contacting subsets of each node’s neighbors at every step,thereby restricting the search space.Many earlier works have mainly focused on the simulation-based analysis of ooding technique,and its variants,in a wired network scenario.Although,there have been some empirical studies in peer-to-peer(P2P)networks,the analytical results are still lacking,especially in the context of mobile P2P networks.In this article,we mathematically model different widely used existing search techniques,and compare with the proposed improved random walk method,a simple lightweight approach suitable for the non-DHT architecture.We provide analytical expressions to measure the performance of the different ooding-based search techniques,and our proposed technique.We analytically derive 3 relevant key performance measures,i.e.,the avg.number of steps needed to nd a resource,the probability of locating a resource,and the avg.number of messages generated during the entire search process.展开更多
The pursuit of high oil recovery rate has been a persistent objective for oil industry. Pseudomonas sp. LP-7 and Bacillus sp. PAH-2 were isolated from oil-contaminated surface soil samples of an oilfield. The antimicr...The pursuit of high oil recovery rate has been a persistent objective for oil industry. Pseudomonas sp. LP-7 and Bacillus sp. PAH-2 were isolated from oil-contaminated surface soil samples of an oilfield. The antimicrobial degradation rates(ADRs) of polymers achieved by LP-7 and PAH-2 were evaluated at a temperature of 35 °C in the mineral salt media during the shaken flask trial. The ADRs of copolymer synthesized by using a surfactant with a concentration of 5% could reach 8.4% for PAH-2 and 15.3% for LP-7. The ADRs of copolymer could reach 10.4% for PAH-2 and 21.3% for LP-7,when the polymer concentration was 2 g/L. All results confirmed that the ADRs of copolymers increased with an increasing content of HDDE(capsaicin derivative monomer) in the polymer. The copolymers also manifested excellent antimicrobial degradation performance in the presence of Cu^(2+), Zn^(2+), and Pb^(2+) ions, respectively, which had great potential for applications in enhanced oil recovery.展开更多
文摘One of the key challenges in ad-hoc networks is the resource discovery problem.How efciently&quickly the queried resource/object can be resolved in such a highly dynamic self-evolving network is the underlying question?Broadcasting is a basic technique in the Mobile Ad-hoc Networks(MANETs),and it refers to sending a packet from one node to every other node within the transmission range.Flooding is a type of broadcast where the received packet is retransmitted once by every node.The naive ooding technique oods the network with query messages,while the random walk scheme operates by contacting subsets of each node’s neighbors at every step,thereby restricting the search space.Many earlier works have mainly focused on the simulation-based analysis of ooding technique,and its variants,in a wired network scenario.Although,there have been some empirical studies in peer-to-peer(P2P)networks,the analytical results are still lacking,especially in the context of mobile P2P networks.In this article,we mathematically model different widely used existing search techniques,and compare with the proposed improved random walk method,a simple lightweight approach suitable for the non-DHT architecture.We provide analytical expressions to measure the performance of the different ooding-based search techniques,and our proposed technique.We analytically derive 3 relevant key performance measures,i.e.,the avg.number of steps needed to nd a resource,the probability of locating a resource,and the avg.number of messages generated during the entire search process.
基金the Natural Science Foundation of China(50673085,41576077)the National High-Tech Research and Development Programme of China(2010AA09Z203)the Fundamental Research Funds for the Central Universities of China(201562026)
文摘The pursuit of high oil recovery rate has been a persistent objective for oil industry. Pseudomonas sp. LP-7 and Bacillus sp. PAH-2 were isolated from oil-contaminated surface soil samples of an oilfield. The antimicrobial degradation rates(ADRs) of polymers achieved by LP-7 and PAH-2 were evaluated at a temperature of 35 °C in the mineral salt media during the shaken flask trial. The ADRs of copolymer synthesized by using a surfactant with a concentration of 5% could reach 8.4% for PAH-2 and 15.3% for LP-7. The ADRs of copolymer could reach 10.4% for PAH-2 and 21.3% for LP-7,when the polymer concentration was 2 g/L. All results confirmed that the ADRs of copolymers increased with an increasing content of HDDE(capsaicin derivative monomer) in the polymer. The copolymers also manifested excellent antimicrobial degradation performance in the presence of Cu^(2+), Zn^(2+), and Pb^(2+) ions, respectively, which had great potential for applications in enhanced oil recovery.
文摘反距离加权插值方法(Inverse Distance Weighted,IDW)是生成数字高程模型(Digital Elevation Model,DEM)的常用内插手段之一,不同的地形应使用合适的IDW距离指数进行插值。本文选取了平原、丘陵、小起伏山地、中起伏山地和大起伏山地5种地形,设计了2组试验,从地形宏观形态和地形微观形态2个方面研究了地形对IDW插值中最优距离指数(Optimal order of distances,OOD)的影响。首先使用狼群算法(Wolf pack algorithm,WPA)计算不同地形区下IDW插值的OOD,分析不同地形之间OOD的分布差异;其次选取坡度、坡向、曲率3个地形因子,计算各采样点的OOD,分析不同地形因子对采样点OOD的影响。结果表明,从平原地区到大起伏山地地区,随着区域内地形起伏度的增加,OOD减小。采样点的OOD在高值区的占比随坡度增大而减小;OOD随坡向变化差异不大;随着地形曲率的增大,OOD在高值区的占比增加,在低值区的占比减小。在较为平坦的地区,例如平原地区,丘陵地区建议使用OOD在3≤a≤4范围内取值进行IDW插值,而在小起伏山地、中起伏山地和大起伏山地等山地区建议采用OOD在1≤a≤2范围内取值进行IDW插值。
