In this article, a way to employ the diffusion approximation to model interplay between TCP and UDP flows is presented. In order to control traffic congestion, an environment of IP routers applying AQM (Active Queue Management) algorithms has been introduced. Furthermore, the impact of the fractional controller and its parameters on the transport protocols is investigated. The controller has been elaborated in accordance with the control theory. The TCP and UDP flows are transmitted simultaneously and are mutually independent. Only the TCP is controlled by the AQM algorithm. Our diffusion model allows a single TCP or UDP flow to start or end at any time, which distinguishes it from those previously described in the literature. 相似文献
In this note, some questions concerning the strong convergence of subgradients of convex functions along a given direction are recalled and posed. It is shown that some open problems in literature are linked to that of the existence of limits of subgradients from subdifferentials along a given segment. 相似文献
Journal of Thermal Analysis and Calorimetry - New coordination compounds have been synthesized by reacting Zn(II) and Co(II) nitrate or acetate in the presence of triethylamine with Schiff-base... 相似文献
Nonlinear Dynamics - The reconstruction of a road accident can be treated as the resolution of an “inverse problem” in mechanics using analytical or numerical models. In the road... 相似文献
Recently, dozens of new psychoactive substances have appeared on the European drug market every year. The most abundant group of these compounds is synthetic cannabinoids. In the first few years of the “legal highs” phenomenon, JWH (John W. Huffman) compounds were especially popular among drug users. However, the group of synthetic cannabinoids is constantly expanding, as new compounds are created by replacing known structural elements with different chemical groups. The problem with the identification of novel substances in forensic laboratories results from the structural similarity of the compounds and the rapid introduction of newer designer drugs on the black market. In this study, the fragmentation patterns of 29 new-type synthetic cannabinoids using electrospray ionization were investigated. The analysis was performed using quadrupole time-of-flight mass spectrometry. Based on measurements carried out under various conditions, the way of fragmentation of the tested compounds that were divided into groups due to their chemical structure was established. The study showed that the bond between the carbon atom of the carbonyl group and the ring or NH group attached to the ring was mainly cleaved. This mechanism was adequate for the fragmentation of first-generation synthetic cannabinoids. This paper presents characteristic ions formed by synthetic cannabinoids (i.e., ions originating from an indole/indazole ring and an adamanyl/naphthalene/quinoline ring) using electrospray ionization. Knowledge of these specific fragments can be used in forensic laboratories to determine the structure of novel compounds from the group of synthetic cannabinoids.
We consider a problem of searching an element in a partially ordered set (poset). The goal is to find a search strategy which minimizes the number of comparisons. Ben-Asher, Farchi and Newman considered a special case where the partial order has the maximum element and the Hasse diagram is a tree (tree-like posets) and they gave an O(n4log3n)-time algorithm for finding an optimal search strategy for such a partial order. We show that this problem is equivalent to finding edge ranking of a simple tree corresponding to the Hasse diagram, which implies the existence of a linear-time algorithm for this problem.Then we study a more general problem, namely searching in any partial order with maximum element. We prove that such a generalization is hard, and we give an -approximate polynomial-time algorithm for this problem. 相似文献
It is shown that the closure of the domain and the closure of the range of a maximal monotone set of type NI are convex sets. This is a positive answer to the question concerning the convexity of the closure of the range of a maximal monotone multifunction, posed in Simons (Minimax and Monotonicity, Lecture Notes in Mathematics 1693. Springer-Verlag, Berlin, 1998, X Open Problems, Problem 27.7). 相似文献
Comprehensive studies of the molecular structures, vibrational frequencies and infrared intensities of the antiperiplanar (ap) and synclinal (sc) conformers of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) have been performed by the density functional (B3LYP) method using the extended 6-311++G(df,pd) basis set. The detailed natural bond orbital (NBO) analysis has revealed the nature of the hyperconjugative interactions, which stabilize each conformer, in the gas phase. The mid-infrared spectra of HFIP in carbon tetrachloride solution were measured, and the experimental intensities of each conformer were obtained by the curve–resolution procedure. The relative abundance of the two conformers, calculated from the relative intensities, shows nearly equimolar ratio (Nsc/Nap ≈ 1), in this solution. The DFT-predicted frequencies show very good agreement with the experimental data. The clear-cut vibrational assignment for each conformer is reported on the basis of the calculated potential energy distributions. Several controversies in an earlier assignment of HFIP have been elucidated. 相似文献
In this paper we deal with the arc ranking problem of directed graphs. We give some classes of graphs for which the arc ranking problem is polynomially solvable. We prove that deciding whether , where G is an acyclic orientation of a 3-partite graph is an NP-complete problem. In this way we answer an open question stated by Kratochvil and Tuza in 1999. 相似文献
The energy dependence of superelastic scattering is measured for electrons on Mg(3(1)P) from threshold to 270 meV with a novel technique. The method uses photoelectrons produced by a narrow bandwidth laser as an approximately monoenergetic incident electron source to collide with excited atoms. Measurements are made at energies as low as 1.5 meV with a resolution of 1 meV near threshold. An efficient magnetic-bottle time-of-flight electron spectrometer allows for the simultaneous measurement of multiple scattering channels. Above-threshold ionization is also observed. The measured energy dependence for transitions from the 3(1)P state to both the 3(3)P and 3(1)S are found to be inversely proportional to the energy from 10 to 270 meV. Below 10 meV, the dependencies are different, with the 3(3)P transition having an E(-1/2) dependence and the 3(1)S channel retaining an E(-1) dependence. 相似文献