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排序方式: 共有138条查询结果,搜索用时 234 毫秒
1.
Haas R. Kencl L. Kind A. Metzler B. Pletka R. Waldvogel M. Frelechoux L. Droz P. Jeffries C. 《IEEE network》2003,17(4):46-54
In this article we present five case studies of advanced networking functions that detail how a network processor (NP) can provide high performance and also the necessary flexibility compared with ASIC. We first review the basic NP system architectures, and describe the IBM PowerNP architecture from the data plane as well as the control plane point of view. We introduce models for the programmer's views of NP that facilitate a global understanding of NP software programming. Then, for each case study, we present results from prototypes as well as general considerations that apply to a wider range of system architectures. Specifically, we investigate the suitability of NP for QoS (active queue management and traffic engineering), header processing (GPRS tunneling protocol), intelligent forwarding (load balancing without flow disruption), payload processing (code interpretation and just-in-time compilation in active networks), and protocol stack termination (SCTP). Finally, we summarize the key features as revealed by each case study, and conclude with remarks on the future of NP. 相似文献
2.
The efficacy of photodynamic therapy is dependent upon the optical dose rate or upon the fractionation schedule on the light. These effects are thought to be limited by the time required for oxygen diffusion from the capillaries, since this therapy can consume oxygen faster than it can be supplied to tissues distant from the blood vessels. Oxygen diffusion and consumption by metabolic and photochemical mechanisms have been modeled here to compare theoretical predictions with experimental results of varying light fractionations and delivered dose rates. The mathematics of the problem have been described in the literature, and the present study extends these calculations to allow a more direct and quantitative comparison with fractionation experiments, using both analytical and numerical arguments. The optimum fraction time was found to depend only on the intercapillary spacing and not on the intensity of irradiation or the concentration of photosensitizer. The calculations indicate that experimentally observed optimum fractionation times of 30 and 60 s correspond to a distance from capillary to cell of approximately 1 mm. These results suggest that the fractionated light irradiation experiments need careful interpretation, and some possible reasons for longer optimum fractionation times are discussed. 相似文献
3.
A tool for modelling and simulation of product development processes has to be able to map the specific stochastic behaviour of these processes. Taking this into consideration, the paper presents an approach to adaptive modelling and simulation using Petri nets. New to this approach is that the process model is generated dynamically at simulation run time. Based on the effective premises and boundary conditions, generic processes are selected, parameterised, and integrated as an instance into the model. Thereby, the model is adapted to its present state at simulation run time. This enhances the quality of the simulation results. 相似文献
4.
Sandra Jeck Philip Scharfer Wilhelm Schabel Matthias Kind 《Chemical Engineering and Processing: Process Intensification》2011,50(5-6):543-550
The development of reliable mathematical models for mass transport in crosslinked polymers and their thorough experimental validation are of substantial interest in the design of technical membrane processes or the assessment of polymer performance when applications such as functional films and protective coatings are concerned.The present study aims at the joint experimental and numerical characterisation of mass transport during water vapour sorption into physically crosslinked poly(vinyl alcohol) membranes. A mathematical model comprising both phase equilibrium and the respective mass transport mechanisms is proposed and verified by means of in situ sorption kinetic measurements. Drawing on the independent determination of equilibrium solvent uptake, the comparison of model calculations and experimental sorption data demonstrates that water transport in the crosslinked polymer membrane is successfully described by pure Fickian diffusion with a simple exponential expression for the solvent diffusion coefficient to account for its pronounced concentration dependency, allowing the latter to be specified quantitatively. 相似文献
5.
Tarek Abu‐Husein Swen Schuster Martin Kind Tobias Santowski Adrian Wiesner Ryan Chiechi Egbert Zojer Andreas Terfort Michael Zharnikov 《Advanced functional materials》2015,25(25):3943-3957
Using a representative model system, here electronic and structural properties of aromatic self‐assembled monolayers (SAMs) are described that contain an embedded, dipolar group. As polar unit, pyrimidine is used, with its orientation in the molecular backbone and, consequently, the direction of the embedded dipole moment being varied. The electronic and structural properties of these embedded‐dipole SAMs are thoroughly analyzed using a number of complementary characterization techniques combined with quantum‐mechanical modeling. It is shown that such mid‐chain‐substituted monolayers are highly interesting from both fundamental and application viewpoints, as the dipolar groups are found to induce a potential discontinuity inside the monolayer, electrostatically shifting the core‐level energies in the regions above and below the dipoles relative to one another. These SAMs also allow for tuning the substrate work function in a controlled manner independent of the docking chemistry and, most importantly, without modifying the SAM‐ambient interface. 相似文献
6.
J. Kind M. Ramm E. Gründemann H.-J. Niclas 《Advanced Synthesis \u0026amp; Catalysis》1994,336(5):439-443
Upon treatment with KF in acetonitrile the zwitterionic Meisenheimer complexes 3 undergo β-elimination leading to potassium 7-(2-aryl-2-oxo-ethylidene)-4,6-dinitro-7,x-dihydrobenzofurazanide 1-oxides 4 in 72–87% yield. Compounds 4 give 7-(2-aryl-2-oxo-ethyl)-4,6-dinitrobenzofuroxans 6 when treated with hydrochloric acid. 4-(2-Aryl-1-dimethylsulfonio-2-oxo-ethylidene)-5,7-dinitro-4,x-dihydrobenzofurazanides 5 are obtained by reaction of 3 with sodium methoxide. The structure of 5e is confirmed by X-ray structure analysis. The reaction of complexes 8 with acetic acid/potassium acetate at 80°C affords 4-(2-aryl-2-oxo-1-pyridinio-ethylidene)-5,7-dinitro-4,x-dihydrobenzofurazanides 9 in moderate yields. 相似文献
7.
Dimitrios Dechouniotis Nikolaos Leontiou Xenofontas Dimitropoulos Andreas Kind Spyros Denazis 《International Journal of Network Management》2009,19(6):513-526
Nowadays traffic monitoring and analysis tools provide poor information about traffic volume without giving any clear view of what the hidden rules and relationships that govern these flows are. Since the majority of flows is generated by services (web browsing, email, p2p) and most of these applications are dependent on many network assets (servers and databases) we should discover the underlying relationships of every application. We present a technique that discovers the hidden relationships among components of a network that consist of parts of specific applications. From time information and flow attributes, such as IP addresses and service ports, our method using a novel hybrid genetic algorithm produces a small set of fuzzy rules that can reveal the underlying relationships over a network without any guidance. These dependencies build a service graph which can become a useful tool for fault localization, monitoring service performance, designing changes and anomaly detection. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
8.
Yvonne Serfert Stephan Drusch Benjamin Schmidt-Hansberg Matthias Kind Karin Schwarz 《Journal of food engineering》2009,95(3):386-392
Aim of the present study was to investigate the impact of the emulsifying carrier matrix constituent, n-octenylsuccinate-derivatised (OSA)-starch, and process conditions on physical characteristics and oxidative stability of microencapsulated fish oil. Furthermore, the effect of the drying medium, i.e. air or nitrogen, on lipid oxidation during spray-drying and subsequent storage was investigated. Particle characteristics and lipid oxidation of microencapsulated fish oil were both influenced by the type of OSA-starch and the drying conditions. The highest oxidative stability was observed for fish oil microencapsulated in OSA-starch with the lowest average molecular weight and glucose syrup spray-dried at a moderate temperature setting. Particle characteristics of the microcapsules were not attributable for differences in lipid oxidation during storage. In spray-dried carrier matrix particles, the particle size increased with increasing average molecular weight of the OSA-starch and was attributed to an increase in air inclusion. Thus differences in lipid oxidation of the microencapsulated fish oil were attributed to differences in air inclusion as affected by the type of OSA-starch. In terms of spray-drying under inert conditions and in the presence of air, lipid oxidation of microencapsulated fish oil was rather attributed to oxygen availability in the feed emulsion than in the drying gas. 相似文献
9.
In scale-model studies of snowdrifting phenomena the similarity requirements cannot all be satisfied. The question of which of the conflicting requirements should be satisfied reduces to one of whether low-density or high-density particles should be used to simulate the snow. Experiments aimed at resolving this question are reported.Wind-tunnel experiments involving saltation of low-density (specific gravity 0.16) and high-density (specific gravity 2.7) particles were carried out. Velocity profiles, particle transport rates and “snowdrift” shapes produced by model snowfences were measured and compared with field data.The results show that when using the low-density particles the saltation process is not dynamically similar to that in actual snowdrifting; important differences in snowdrift shape and particle transport rates occur. The lack of similarity apparently stems from aerodynamic lift forces which are not negligible in comparison with the weight of the low-density particles. The use of high-density particles is recommended when modeling snowdrifting phenomena. 相似文献
10.