A Novel Optimal Mapping Algorithm With Less Computational Complexity for Virtual Network Embedding

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. Network Virtualization (NV) is widely accepted as one enabling technology for future network, which enables multiple Virtual Networks (VNs) with different paradigms and protocols to coexist on the shared Substrate Network (SN). One key challenge in network virtualization is Virtual Network Embedding (VNE), which maps a virtual network onto the shared SN. Since VNE is NP-hard, existing efforts mainly focus on proposing heuristic algorithms that try to achieve feasible VN embedding in reasonable time, consequently the resulted embedding is not optimal. To tackle this difficulty, we propose a candidate assisted (CAN-A) optimal VNE algorithm with lower computational complexity. The key idea of the CAN-A algorithm lies in constructing the candidate substrate node subset and the candidate substrate path subset before embedding. This reduces the mapping execution time substantially without performance loss. In the following embedding, four types of node and link constraints are considered in the CAN-A algorithm, making it more applicable to realistic networks. Simulation results show that the execution time of CAN-A is hugely cut down compared with pure VNE-MIP algorithm. CAN-A also outperforms the typical heuristic algorithms in terms of other performance indices, such as the average virtual network request (VNR) acceptance ratio and the average virtual link propagation delay

Observation of a pressure-induced transition from interlayer ferromagnetism to intralayer antiferromagnetism in Sr4Ru3O10

Sr4Ru3O10 is a Ruddlesden-Popper compound with triple Ru-O perovskite layers separated by Sr-O alkali layers. This compound presents a rare coexistence of interlayer (c-axis) ferromagnetism and intralayer (basal-plane) metamagnetism at ambient pressure. Here we report the observation of pressure-induced, intralayer itinerant antiferromagnetism arising from the interlayer ferromagnetism. The application of modest hydrostatic pressure generates an anisotropy that causes a flattening and a tilting of RuO6 octahedra. All magnetic and transport results from this study indicate these lattice distortions diminish the c-axis ferromagnetism and basal-plane metamagnetism, and induce a basal-plane antiferromagnetic state. The unusually large magnetoelastic coupling and pressure tunability of Sr4Ru3O10 makes it a unique model system for studies of itinerant magnetism.Comment: 6 figure

Anti-Stokes scattering and Stokes scattering of stimulated Brillouin scattering cascade in high-intensity laser-plasmas interaction

The anti-Stokes scattering and Stokes scattering in stimulated Brillouin scattering (SBS) cascade have been researched by the Vlasov-Maxwell simulation. In the high-intensity laser-plasmas interaction, the stimulated anti-Stokes Brillouin scattering (SABS) will occur after the second stage SBS rescattering. The mechanism of SABS has been put forward to explain this phenomenon. And the SABS will compete with the SBS rescattering to determine the total SBS reflectivity. Thus, the SBS rescattering including the SABS is an important saturation mechanism of SBS, and should be taken into account in the high-intensity laser-plasmas interaction.Comment: 6 pages, 5 figure

An energy-aware protocol for data gathering applications in wireless sensor networks

2006-2007 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

Metropolitan Trends and Challenges in China: The Demographic Dimension

Over the past century China has been transforming from a rural to an urban economy. In the course of this transition, significant regional variations have emerged in urban growth, with a gap forming between coastal and inland areas. This report focuses on Chinas metropolitan regions: Shanghai, Beijing, and Guangdong which are the most socioeconomically advanced regions in China. It is the first outcome of the joint IIASA and Beijing University project on "Regional Urbanization and Human Capital Projections for China," which focuses on demographic matters, and it will analyze the following major issues: What factors have contributed to the growth of Chinas metropolitan areas over the last two decades? What specific urbanization patterns occur in the transformation from a rural to an urban economy? How does demography drive the speed of urbanization, in particular, in the metropolitan areas? How is IIASAs multistate method used for urbanization projections and what are its advantages and disadvantages? What challenges will China face in the near future as a result of rapid metropolitan growth? This paper suggests that the growth of Chinese mega-urban regions will have knock-on effects at the global level in the medium term

Quantification of N and C cycling during aerobic composting, including automated direct measurement of N-2, N2O, NO, NH3, CO2 and CH4 emissions

Closing the carbon (C) and nitrogen (N) balance has yet to be achieved in aerobic bioprocess due to current methodological drawbacks in the frequency of sampling and detection and the challenge in direct measurement of instantaneous N-2 emission. To address this issue, a novel system was developed enabling simultaneous and online determination of gaseous C and N species (N-2, N2O, NO, NH3, CO2 and CH4) from aerobic composting at a high frequency of 120 times center dot d(-1). A helium-oxygen gas mixture was used to replace the air in the system to enable direct measurement of N-2 emission, and three different gas exchange methods were assessed in their ability to minimize atmospheric background N-2: 1) the N-2-free gas purging method; 2) one cycle of the evacuation-refilling procedure; 3) one cycle of evacuating and refilling followed by N-2-free gas purging. Method 3 was demonstrated as an optimumN(2)-removal method, and background N-2 concentrations decreased to similar to 66 mu mol center dot mol(-1) within 11.6 h. During the N-2-free gas purging period, low temperature incubation at 15 degrees C reduced CO2, CH4, NO, N2O and NH3 losses by 80.5 %, 41-fold, 10-fold, 11,403-fold and 61.4 %, respectively, compared with incubation at 30 degrees C. Therefore, a fast and low-perturbation N-2 removal method was developed, namely the evacuating/refilling-low temperature purging method. Notably, all C and N gases exhibited large within-day variations during the peak emission period, which can be addressed by high-frequency measurement. Based on the developed method, up to 97.8 % of gaseous C and 95.6 % of gaseous N losses were quantified over a 43-day compost incubation, with N-2 emission accounting (on average) for 5.8% of the initial total N. This system for high frequency measurement of multiple gases (including N-2) provides a novel tool for obtaining a deeper understanding of C andN turnover andmore accurate estimation of reactive N and greenhouse gas emissions during composting

Effects of frequency-modulated pump on stimulated Brillouin scattering in inhomogeneous plasmas

The effects of the frequency-modulated pump on stimulated Brillouin scattering (SBS) in a flowing plasma are investigated by theory analysis, three-wave simulations, one-dimensional Vlasov-Maxwell simulations, and particle-in-cell (PIC) simulations. The resonance points of SBS oscillate in a certain spatial region as time when frequency modulations are applied. There exists a certain frequency modulation that makes the velocity of resonant points close to the group velocity of seed laser, which increases the SBS reflectivity. And the SBS could be suppressed by frequency modulation with larger bandwidth. In the Vlasov-Maxwell simulations, the muti-locations autoresonance is observed in narrow bandwidth frequency modulation case, which can also increase the SBS reflectivity. Finally, one-dimensional PIC simulations confirm our conclusions and the movement of resonant points by autoresonance is consistent with our theoretical predications

Electrical Control of Structural and Physical Properties via Strong Spin-Orbit Interactions in Sr2IrO4

Electrical control of structural and physical properties is a long-sought, but elusive goal of contemporary science and technology. We demonstrate that a combination of strong spin-orbit interactions (SOI) and a canted antiferromagnetic (AFM) Mott state is sufficient to attain that goal. The AFM insulator Sr2IrO4 provides a model system in which strong SOI lock canted Ir magnetic moments to IrO6-octahedra, causing them to rigidly rotate together. A novel coupling between an applied electrical current and the canting angle reduces the N\'eel temperature and drives a large, non-linear lattice expansion that closely tracks the magnetization, increases the electron mobility, and precipitates a unique resistive switching effect. Our observations open new avenues for understanding fundamental physics driven by strong SOI in condensed matter, and provide a new paradigm for functional materials and devices.Comment: 5 figures; to be published in Physical Review Letter