Quality of service (QoS) provisioning generally assumes more than one QoS measure that implies that QoS routing can be categorized
as an instance of routing subject to multiple constraints: delay jitter, bandwidth, cost, etc. We study the problem of constructing
multicast trees to meet the QoS requirements of real-time interactive applications where it is necessary to provide bounded
delays and bounded delay variation among the source and all destinations while keeping overall cost of the multicast tree
low. The main contribution of our work is a new strategy for constructing multiconstrained multicast trees. We first derive
mathematically a new delay-variation estimation scheme and prove its efficiency. Thereafter, we propose a simple and competitive
(in terms of running time) heuristic algorithm, for delay and delay variation constrained routing problem based on the proposed
delay-variation estimation scheme and using the Extended Prim-Dijkstra tradeoffs’ algorithm. Our contribution also extends
previous works in providing some properties and analyses of delay bounded paths satisfying delay variation constraints. Extensive
simulation results show that our algorithm outperforms DVDMR in terms of multicast delay variation with the same time complexity
as DVDMR. 相似文献
Journal of Inorganic and Organometallic Polymers and Materials - Recently, great efforts have been dedicated to the construct and design of low cost and high-performance photocatalysts for the... 相似文献
The elastic properties of single-crystalline erbia (Er2O3) at room temperature have been investigated using resonant ultrasound spectroscopy. The three independent stiffness constants of anisotropic Er2O3 cubic type-C crystals have been measured. The values of the stiffness constants were c 11= 256.4 GPa, c 12= 146.8 GPa, and c 44= 75.2 GPa. From the stiffness constants, the estimated values for dense polycrystalline erbia for Young's modulus, the shear modulus, the bulk modulus, and Poisson's ratio at room temperature were 179 GPa, 67 GPa, 183.3 GPa, and 0.337, respectively. The value of Young's modulus is a minimum along [001] and a maximum along [111]. The value of the shear modulus is independent of the direction in the (001) and (111) planes, whereas it decreases in (11¯0) from 75 GPa along [001] to 55 GPa along [110]. 相似文献
This paper is concerned with Electroencephalography (EEG) seizure prediction, which means the detection of the pre-ictal state prior to ictal activity occurrence. The basic idea of the proposed approach for EEG seizure prediction is to work on the signals in the Hilbert domain. The operation in the Hilbert domain guarantees working on the low-pass spectra of EEG signal segments to avoid artifacts. Signal attributes in the Hilbert domain including amplitude, derivative, local mean, local variance, and median are analyzed statistically to perform the channel selection and seizure prediction tasks. Pre-defined prediction and false-alarm probabilities are set to select the channels, the attributes, and bins of probability density functions (PDFs) that can be useful for seizure prediction. Due to the multi-channel nature of this process, there is a need for a majority voting strategy to take a decision for each signal segment. Simulation results reveal an average prediction rate of 96.46%, an average false-alarm rate of 0.028077/h and an average prediction time of 60.1595 min for a 90-min prediction horizon.
Advances in the field of automation have meant hitherto complex manual cell-based assays can now be automated. These improvements have brought significant enhancements in throughput, data fidelity and consistency, and allowed a reallocation of constrained resources.Building upon these improvements, we have linked our automated cell-based screening system, Assay Platform™, to Activity Base (IDBS), a software package designed to automate the analysis of HTS data. Customisation of this package has resulted in software that can identify ‘active’ compounds and re-pick them ‘on the fly’ from the original compound plates for triplicate re-testing without operator intervention.Based on an operator initially defining ‘normal’ parameters for assay activity in Activity Base, combined with an automated quality control software module that checks data fidelity, wells containing ‘active’ compounds can be re-picked and re-tested at the end of an automated screening run. Automating cell-based assays has significantly improved productivity, and, with the synergism of Activity Base, has given us greater power to complete each screening run and report ‘active’ compounds to Chemistry more rapidly. This article presents our approach to the automation of cell-based Fluorescent Imaging Plate Reader (FLIPR) screening together with automated active re-test confirmation using Activity Base. 相似文献
Over recent years, there has been a clear increase in the frequency of reported flooding events around the world. Gabion structures offer one means of flood mitigation in dam spillways. These types of structures provide an additional challenge to the computational modeller in that flow through the porous gabions must be simulated. We have used a computational model to investigate the flow over gabion stepped spillways. The model was first validated against published experimental results. Then, gabion stepped spillways with four different step geometries were tested under the same conditions in order to facilitate inter-comparisons and to choose the best option in terms of energy dissipation. The results show that normal gabion steps can dissipate more energy than overlap, inclined, and pooled steps. An intensive set of tests with varying slope, stone size, and porosity were undertaken. The location of the inception point and the water depth at this point obtained from this study were compared with those from existing formulae. Two new empirical equations have been derived, on the basis of a regression analysis, to provide improved results for gabion stepped spillways. 相似文献
Reliability analysis of millimetric wave propagation in airdland is presented. Based on long term rain data and sand storm record in Riyadh, the paper estimates the outage due to individual effects. The total outage due to rain and sand is then derived under various storm conditions. It is particularly shown that rain and sand storms may have comparable effects on link reliability for typical storms. For adverse storm conditions marked by large and wet particles, rain will have less effect on system reliability compared to sand storms. 相似文献
The effects of hippocampal ablation on acquisition rates and temporal characteristics of classically conditioned nictitating membrane responses were examined in 54 New Zealand albino rabbits trained with a 150-, 300-, or 600-msec interstimulus interval. Acquisition rates were accelerated in the 150- and 600-msec groups. No effect was present in the 300-msec group. Response onset latencies were also affected in the 150-msec group. Results indicate that damage to the hippocampus influences the acquisition of classically conditioned responses only when temporal parameters are relatively complex. Findings also support the notion that the hippocampus modulates learned motor behavior by a neural model of the response to be executed. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献