Dynamic spectrum access (DSA) scheme in Cognitive Radio (CR) can solve the current problem of scarce spectrum resource effectively, in which the unlicensed users (i.e. Second Users, SUs) can access the licensed spectrum in opportunistic ways without interference to the licensed users (i.e. Primary Users, PUs). However, SUs have to vacate the spectrum because of PUs coming, in this case the spec...

Quasi-Monte Carlo (QMC) points are a substitute for plain Monte (MC) that greatly improve integration accuracy under mild assumptions on the problem. Because QMC can give errors o(1/n) as $$n\rightarrow \infty $$ , and randomized versions attain root mean squared o(1/n), changing even one point change estimate by an amount much larger than error would have been worsen convergence rate. As resul...

Recently, many people enjoy accessing wireless network to conveniently collect their required information or happily surf within the Internet worldwide by exploiting wireless mobility, flexibility and availability. However, the more sessions accessing the channel, the more packet dropping rate. In this paper, we propose a polling access control scheme which in its PCF mode deploys non-preemptiv...

Lambda-lifting a functional program transforms it into a set of recursive equations. We present the symmetric transformation: lambda-dropping. Lambda-dropping a set of recur-sive equations restores block structure and lexical scope. For lack of scope, recursive equations must carry around all the parameters that any of their callees might possibly need. Both lambda-lifting and lambda-dropping t...

In sandy soils of the southeastern USA coastal plains, crop production is limited by low water holding capacity and compacted soil layers that reduce root growth and productivity. Polyacrylamide (PAM) was added to sandy coastal plain soils to improve physical properties and yield. Soils were amended with linear and cross-linked PAMs. Treatments and controls included the following: (1) spraying ...

Wireless Body Sensor Networks (WBSNs) involve a convergence of biosensors, wireless communication and networks technologies. WBSN enables real-time healthcare services to users. Wireless sensors can be used to monitor patients’ physical conditions and transfer real time vital signs to the emergency center or individual doctors. Wireless networks are subject to more packet loss and congestion. T...

the number of students who can not complete school programs is a serious problem facing many educational systems in all educational levels . drop oui and repetition are one of the most common matters that many educators and researchers interest to study it. there are many reasons on the retention and non-completion patterns, but it can find rarely a philosophical viewpoint on the problem. the a...

Leafcutting ants (Atta and Acromyrmex) sometimes form piles or caches of leaves on foraging trails. Laboratory experiments have shown that leaf caching at the nest entrance by Atta cephalotes and Atta colombica is adaptive because it occurs when a colony’s leaf delivery rate exceeds its leaf-processing rate and serves to increase the probability that a dropped leaf is eventually recovered. We e...