CMLP: Exploiting Caches at Multiple Levels of Proxies to Enhance Seamless Mobility Support in Information-Centric Networks

The recent evolution of the Internet towards "Information-centric" transfer modes has renewed the interest in exploiting proxies to enhance seamless mobility. In this work, we focus on the case of multiple levels of proxies in ICN architectures, in which content requests from mobile subscribers and the corresponding items are proactively cached to these proxies at different levels. Specifically, we present a multiple-level proactive caching model that selects the appropriate subset of proxies at different levels and supports distributed online decision procedures in terms of the tradeoff between delay and cache cost. We show via extensive simulations the reduction of up to 31.63% in the total cost relative to Full Caching, in which caching in all 1-level neighbor proxies is performed, and up to 84.21% relative to No Caching, in which no caching is used. Moreover, the proposed model outperforms other approaches with a flat cache structure in terms of the total cost.

Physics of multiple level hairpin vortex structures in turbulence

Previous experimental and numerical studies have revealed that the hairpin vortex is a basic flow element of transitional boundary layer. The hairpin vortex is believed to have legs, necks and a ring head. Based on our DNS study, the legs and the ring head are generated separately by different mechanisms. The legs function like an engine to generate low speed zones by rotation, create shear layers with surrounding high speed neighbor fluids, and further cause vortex ring formation through shear layer instability. In addition, the ring head is Ω-shaped and separated from quasi-streamwise legs from the beginning. Contrary to the classical concept of ＂vortex breakdown＂, we believe transition from laminar flow to turbulence is a ＂buildup＂ process of multiple level vortical structures. The vortex tings of first level hairpins are mostly responsible for positive spikes, which cause new vorticity rollup, second level vortex leg formation and finally smaller second level vortex ring generation. The third and lower level vortices are generated following the same mechanism. In this paper, the physical process from A-vortex to mul- ti-level hairpin vortices is described in detail.

Predicting urbanization level by main element analysis and multiple linear regression---taking Xiantao district in Hubei Province as an example

In this paper we firstly select main factors relating to urbanization level of Xiantao District in Hubei Province by main element, then, make model of urbanization level by analysis of multiple liner regression, and lastly predict its urbanization level

Image segmentation by level set evolution with region consistency constraint

Image segmentation is a key and fundamental problem in image processing,computer graphics,and computer vision.Level set based method for image segmentation is used widely for its topology flexibility and proper mathematical formulation.However,poor performance of existing level set models on noisy images and weak boundary limit its application in image segmentation.In this paper,we present a region consistency constraint term to measure the regional consistency on both sides of the boundary,this term defines the boundary of the image within a range,and hence increases the stability of the level set model.The term can make existing level set models significantly improve the efficiency of the algorithms on segmenting images with noise and weak boundary.Furthermore,this constraint term can make edge-based level set model overcome the defect of sensitivity to the initial contour.The experimental results show that our algorithm is efficient for image segmentation and outperform the existing state-of-art methods regarding images with noise and weak boundary.

Concurrent Two-Scale Topology Optimization of Thermoelastic Structures Using a M-VCUT Level Set Based Model of Microstructures

By analyzing the results of compliance minimization of thermoelastic structures,we observed that microstructures play an important role in this optimization problem.Then,we propose to use a multiple variable cutting(M-VCUT)level set-based model of microstructures to solve the concurrent two-scale topology optimization of thermoelastic structures.A microstructure is obtained by combining multiple virtual microstructures that are derived respectively from multiple microstructure prototypes,thus giving more diversity of microstructure and more flexibility in design optimization.The effective mechanical properties of microstructures are computed in an off-line phase by using the homogenization method,and then a mapping relationship between the design variables and the effective properties is established,which gives a data-driven model of microstructure.In the online phase,the data-driven model is used in the finite element analysis to improve the computational efficiency.The compliance minimization problem is considered,and the results of numerical examples prove that the proposed method is effective.

Theoretical Analysis of Gain and Threshold Current Density for Long Wavelength GaAs-Based Quantum-Dot Lasers'

Quantum dot gain spectra based on harmonic oscillator model are calculated including and excluding excitons. The effects of non-equilibrium distributions are considered at low temperatures. The variations of threshold current density in a wide temperature range are analyzed and the negative characteristic temperature and oscillatory characteristic temperature appearing in that temperature range are discussed. Also,the improvement of quantum dot lasers＇ performance is investigated through vertical stacking and p-type doping and the optimal dot density, which corresponds to minimal threshold current density,is calculated.

A two-dimensional numerical wave flume based on SA-MPLS method

A spatially adaptive (SA) two-dimensional (2-D) numerical wave flume is presented based on the quadtree mesh system,in which a new multiple particle level set (MPLS) method is proposed to solve the problem of interface tracking,in which common intersection may be traversed by multiple interfaces.By using the adaptive mesh technique and the MPLS method,mesh resolution is updated automatically with time according to flow characteristics in the modeling process with higher resolution around the free surface and the solid boundary and lower resolution in less important area.The model has good performance in saving computer memory and CPU time and is validated by computational examples of small amplitude wave,second-order Stokes wave and cnoidal wave.Computational results also indicate that standing wave and wave overtopping are also reasonably simulated by the model.

3D Simulation of Flow with Free Surface Based on Adaptive Octree Mesh System

The technique of adaptive tree mesh is an effective way to reduce computational cost through automatic adjustment of cell size according to necessity. In the present study, the 2D numerical N-S solver based on the adaptive quadtree mesh system was extended to a 3D one, in which a spatially adaptive oetree mesh system and multiple particle level set method were adopted for the convenience to deal with the air-water-structure multiple-medium coexisting domain. The stretching process of a dumbbell was simulated and the results indicate that the meshes are well adaptable to the free surface. The collapsing process of water column impinging a circle cylinder was simulated and from the results, it can be seen that the processes of fluid splitting and merging are properly simulated. The interaction of second-order Stokes waves with a square cylinder was simulated and the obtained drag force is consistent with the result by the Morison＇s wave force formula with the coefficient values of the stable drag component and the inertial force component bein~ set as 2.54.

Metropolitan Emblems or Symbols in Globalization？ Both for the Future of Metropolises and Their Citizens

This research concerns on ＂metropolis and metropolisation＂： what is new with the symbols of city local life and the emblems of global competition？ From New York, Rome, Barcelone, Paris and Bordeaux, the same question demands specific answers： can we live and appreciate urban and metropolitan symbols and emblems together or on their own？ That is the question for towns and the future of their citizens. Confrontation of urban sites and observed places with the plural points of view of their establishment, their designers and urban skills, and their inhabitants and citizens. The combination of these several points of view always make a richer discovery than their disciplinary partition and monopoly.

An Algorithm for LOD by Merging Near Coplanar Faces Based on Gauss Sphere

LOD (Level of Detail) models are widely used recently to accelerate the rendering of 3D scenes. An algorithm that creates multiple levels of detail for 3D scene by merging near-coplanar faces is presented in this paper. First a Gauss sphere is defined for the model of scene and it is divided into meshes near-uniformly. Then, the faces of objects are attached to the respective spherical meshes according to their normal direction. If faces attached to the same mesh are connected with each other, they are merged to form a near coplanar patch (Superface). Isolated vertices inside the patch are removed and the patch is retriangulated. To further improve the simplification, vicinity vertices on the boundary of the surface patch are merged. In the algorithm, a planar separate rule planar-enneatree is adopted to set up a hierarchical structure of the Gauss sphere, which is used to support the hierarchical model of the scene (LOD). The experimental result shows that the algorithm can achieve desired simplification effects.