排序方式: 共有35条查询结果,搜索用时 15 毫秒
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Luxing Yang Moez Draief Xiaofan Yang 《Mathematical Methods in the Applied Sciences》2017,40(5):1396-1413
The node‐based epidemic modeling is an effective approach to the understanding of the impact of the structure of the propagation network on the epidemics of electronic virus. In view of the heterogeneity of the propagation network, a heterogeneous node‐based SIRS model is proposed. Theoretical analysis shows that the maximum eigenvalue of a matrix related to the model determines whether viruses tend to extinction or persist. When viruses persist, the connectedness of the propagation network implies the existence and uniqueness of a viral equilibrium, and a set of sufficient conditions for the global stability of the viral equilibrium are given. Numerical examples verify the correctness of our results. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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Abdullah S. AlRamadan Moez Ben Houidi Julien Sotton Marc Bellenoue Bengt Johansson S. Mani Sarathy 《Proceedings of the Combustion Institute》2021,38(4):5539-5548
One approach to enhancing the thermal efficiency of combustion systems is to burn fuels at ultra-lean conditions (equivalence ratio below 0.5). It has been recently reported that the auto-ignition of some hydrocarbon fuels, under specific temperature, pressure, and mixture conditions, releases heat in three distinctive stages. The three auto-ignition stages can be divided as a first low-temperature auto-ignition stage with conventional low temperature, and a high-temperature stage separated into two sub-stages. This study presents ignition delay time measurements of n-heptane and methyl-cyclohexane (MCH) mixtures in a flat piston rapid compression machine (RCM) under ultra-lean conditions. It provides experimental evidence of three-stage auto-ignition. This phenomenon of delayed high-temperature heat release is seldom reported in the literature and this is the first time to be reported for these types of fuels. The experiments cover two binary n-heptane/MCH mixtures of 15/85 and 70/30 by volume, pressures of 11 bar and 16 bar, temperature range of 700 to 900 K, and equivalence ratio of 0.4. The RCM optical access was utilized for high-speed chemiluminescence imaging. Detailed chemical kinetic simulations in a homogenous batch reactor with variable volume were conducted to further interrogate the three-stage auto-ignition phenomenon. Chemiluminescence shows that three-stage auto-ignition occurs in the adiabatically compressed end-gas, which indicates that this phenomenon is chemically-driven and is not induced by a thermal stratification in the RCM experiments. The model predicts the features of three-stage auto-ignition, which were experimentally observed at temperatures approximately below 750 K. As expected, significant discrepancies are observed in the ignition delays of experiment and simulation in the negative temperature coefficient (NTC) region. The simulation of the n-heptane/MCH 70/30 mixture shows better agreement with experiments in the Positive Temperature Coefficient (PTC) region compared to the 15/85 mixture. 相似文献
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Moez Guettari Riadh Gomati Abdelhafidh Gharbi 《Journal of Macromolecular Science: Physics》2013,52(3):552-562
The behavior of polyvinylpyrrolidone in mixed water/methanol solvents was studied by rheoviscosimetry over a temperature range of 20°C–40°C. For the lower temperatures of this range, the intrinsic viscosity variation of the polymer vs. methanol molar fraction shows structural transitions (coil–globule–coil). This transition, which is usually attributed to the cononsolvency phenomenon, agrees with our previously published results obtained by dynamic light scattering. For higher temperatures, near 40°C, the intrinsic viscosity increase shows an expansion of the polymer over the alcohol molar fraction range 0.2 < X A < 0.5. This last result can be attributed to the water/alcohol complex destruction under temperature increase. The “excess viscosity” of the polymer-mixed solvents vanishes with increasing temperature and becomes positive at 40°C. So, the polymer chain tends to transit from a globular to an ideal chain in the middle composition range of the mixed solvents. 相似文献
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This article addresses a wave equation on a exterior domain in ? d (d odd) with nonlinear time-dependent dissipation. Under a microlocal geometric condition we prove that the decay rates of the local energy functional are obtained by solving a nonlinear non-autonomous differential equation 相似文献
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This paper deals with the problem of synchronization of chaotic dynamical systems. We consider a drive-response type of synchronization via a scalar transmitted signal. Unlike most works we consider the presence of some unknown inputs in the drive system and that no knowledge about their nature is available. A reduced-order observer-based response system is designed to synchronize with the missing states. We show that under some assumptions the synchronization is exponentially achieved. The efficiency of our method is confirmed by numerical simulations of two well-known chaotic systems: Chua’s circuit and Lur’e system. 相似文献
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The design of micro‐optical resonator arrays are introduced and tailored towards refractive index sensing applications, building on the previously unexplored benefits of open dielectric stacks. The resonant coupling of identical hollow cavities present strong and narrow spectral resonance bands beyond that available with a single Fabry Perot interferometer. Femtosecond laser irradiation with selective chemical etching is applied to precisely fabricate stacked and waveguide‐coupled open resonators into fused silica, taking advantage of small 12 nm rms surface roughness made available by the self‐alignment of nanograting planes. Refractive index sensing of methanol‐water solutions confirm a very attractive sensing resolution of 6.5 × 10−5 RIU. Such high finesse optical elements open a new realm of optofluidic sensing and integrated optical circuit concepts for detecting minute changes in sample properties against a control solution that may find importance in chemical and biological sensors, telecom sensing networks, biomedical probes, and low‐cost health care products.
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Guettari Moez Ajroudi Lilia Jouini Karima Tajouri Tahar Herráez José V. 《Journal of solution chemistry》2014,43(8):1414-1420
Journal of Solution Chemistry - The aim of this work is to develop a simple theory to study the effect of the addition of an impurity on the interaction between unlike molecules in mixed liquids.... 相似文献
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Jeremy Pitt Daniel Ramirez-Cano Moez Draief Alexander Artikis 《Computational & Mathematical Organization Theory》2011,17(4):344-378
Ad hoc networks can be formed from arbitrary collections of sensors, mobile routers, or business processes. These networks
are open systems, in the sense that the network nodes share a common language but do not necessarily share a common goal or
common knowledge, and there is no centralised controller or global data repository. Such systems have numerous advantages
in terms of enabling autonomous, heterogeneous components to achieve individual goals without central direction and with only
partial knowledge. However, operational problems stem from potential conflicts over resource allocation, miscommunication,
and sub-ideal operation, and the general need of embedded systems to change behaviour according to changes in the environment.
To address these problems, we propose to converge aspects of norm-governed specification from distributed multi-agent systems,
opinion formation from social networks, and voting procedures from computational social choice. In particular, we develop
a prototype system which interleaves gossiping, expressed preferences (voting) and norms, to configure rules and assign roles.
This is another demonstration of the use of socially-inspired mechanisms for regulation of decentralised systems and a key
step towards the realization of organized adaptation for open multi-agent systems. 相似文献