WLAN与LTE网络间IP流移动性的控制策略探讨

通过对3GPP标准的WLAN与LTE融合以及ANDSF等相关内容的研究,探讨利用ANDSF实现WLAN与LTE网络间IP流移动性的策略控制,并从组网架构、策略类型、策略组合等方面给出了可行性建议。

一种基于代理移动IPv6的全局移动性管理结构和协议

该文定义一种基于代理移动IPv6的全局移动性管理结构和协议,简称为PMIPGMM。在PMIPGMM中,由网络实体而不是移动节点完成移动性管理,另外消除了移动节点和接入路由器之间分发数据的无线链路隧道负荷。为与熟知的层次移动IPv6协议比较,基于液体流移动性模型,分别给出了每个协议下,移动节点在平均域停留时间内产生的位置更新、数据分发和总费用函数。分别研究了各种系统参数对费用函数的影响。分析结果表明所提出的基于代理移动IPv6的全局移动性管理协议可以保证低的总费用。

移动数据流量卸载技术的比较研究

首先描述了几种主要的移动数据流量卸载技术,包括Wi-Fi、Femtocell以及机会通信网络等,随后分别介绍了相应的网络架构,并分析了各种技术的优缺点,最后展望了今后移动数据卸载技术的重点研究方向。

WLAN和移动网互通技术分析

业界对WLAN与移动网的互通技术研究日益深入,新的互通技术层出不穷。这些技术有何特征,该如何与实际网络部署相结合,技术又有何发展方向,这些问题都将是本文分析研究的重点。

WLAN/LTE异构网络中网络选择优化算法

提出了一种在WLAN/LTE异构网络环境下接入网络选择的优化方案。方案不仅考虑了移动节点中的可用参数和它当前所关联的网络及备选网络,还对异构网络的整体性能进行了优化。介绍了一种基于著名的装箱问题近似解的优化模型和分布式处理信号的方案。最后用模拟器对方案进行了验证,结果表明,相比只根据本地可用信息来进行切换,上述解决方案对网络的性能有明显改善。

LBMA： A Novel Locator Based Mobility Support Approach in Named Data Networking

To enhance seamless source mobility support in the mobile NDN(Named Data Networking) environment,we propose a novel Locator Based Mobility support Approach,dubbed LBMA.In this approach,we assign a unique topologically layered locator to each AR(Access Route)in NDN network,and extend the AR with additional functionalities,such as caching and forwarding Interest packets on behalf of the source.Meanwhile,we add an optional field to the original NDN packet,and modify the Outgoing Interface(s) field in the AR's original FIB(Forwarding Information Base)entries,to record the mobility status and the current locator of the source.Specifically,the consumer in LBMA can continue the interrupted communication,without delivering Interest packets towards the old location of the source,nor waiting for all relevant devices completing the FIB entries updating.The performance analysis result indicates that LBMA has lower handoff cost and shorter handoff latency,compared with other existing source mobility support approaches.

Characteristics of unsteady flow in porous media while considering threshold pressure gradient with Green＇s function

The flow behavior in porous media with threshold pressure gradient(TPG) is more complex than Darcy flow and the equations of motion, and outer boundary and inner boundary with TPG are also different from Darcy flow for unsteady flow of a producing well in a reservoir. An analytic method to solve this kind of problem is in a need of reestablishment. The classical method of Green's function and Newman product principle in a new way are used to solve the unsteady state flow problems of various shapes of well and reservoir while considering the TPG. Four Green's functions of point, line, band and circle while considering the TPG are achieved. Then, two well models of vertical well and horizontal well are built and simultaneously the function to calculate the moving boundary of each well model is provided. The results show that when considering TPG the pressure field is much different, which has a sudden pressure change, with a moving boundary in it. And the moving boundary of each well model increases with time but slows down rapidly, especially when the TGP is large.

Effect of Sudden Increase of Solid Feed Rate on the Arching in Hoppers Connected to a Moving-Bed Standpipe with Interstitial Gas Flow

In this paper, a model is proposed for the prediction of the width of arching in hoppers resulted from sudden changes in solid feed rates. Such changes in solid feed rate usually come from the collision on the surface of the moving-bed in the standpipe. The model also takes into account the effect of the powder height in the standpipe of the hopper. The model proves to be adaptable for predicting operational conditions to avoid arching by keeping constant powder height in the main standpipe with interstitial gas flow.

Epidemic-Like Proximity-Based Traffic Offloading

Cellular networks are overloaded due to the mobile traffic surge,and mobile social networks(MSNets) can be leveraged for traffic offloading.In this paper,we study the issue of choosing seed users for maximizing the mobile traffic offloaded from cellular networks.We introduce a gossip-style social cascade(GSC) model to model the epidemic-like information diffusion process in MSNets.For static-case and mobile-case networks,we establish an equivalent view and a temporal mapping of the information diffusion process,respectively.We further prove the submodularity in the information diffusion and propose a greedy algorithm to choose the seed users for traffic offloading,yielding a sub-optimal solution to the NP-hard traffic offloading maximization(TOM) problem.Experiments are carried out to study the offloading performance,illustrating that the greedy algorithm significantly outperforms the heuristic and random algorithms,and user mobility can help further reduce cellular load.

Developing a 2D vertical flow and sediment transport model for open channels using the Youngs-VOF method

A 2D vertical （2DV） numerical model, without o-coordinate transformation in the vertical direction, is developed for the simulation of flow and sediment transport in open channels. In the model, time-averaged Reynolds equations are closed by the k-e nonlinear turbulence model. The modified Youngs- VOF method is introduced to capture free surface dynamics, and the free surface slope is simulated using the ELVIRA method. Based on the power-law scheme, the k-e model and the suspended-load transport model are solved numerically with an implicit scheme applied in the vertical plane and an explicit scheme applied in the horizontal plane. Bedload transport is modeled using the Euler-WENO scheme, and the grid-closing skill is adopted to deal with the moving channel bed boundary. Verification of the model using laboratory data shows that the model is able to adequately simulate flow and sediment transport in open channels, and is a good starting point for the study of sediment transport dynamics in strong nonlinear flow scenarios.

Mobile Business Process Personalization for End Users

Many specified business needs in enterprise context cannot be effectively satisfied using current business process technology.This phenomenon is called the "long tail" of business processes.In addition,more and more business applications need to be accessed from mobile devices such as smartphones by enterprise end users.This paper attempts to solve both two challenges above.A lightweight event-driven process model is proposed aiming at satisfying the spontaneous business needs in enterprise.And we design an innovative wizard,which works like a tutorial,guiding end users in creating this lightweight process model.Moreover,end users are allowed to interact with the process created by themselves on smartphones.Finally,the usability of our approach was evaluated on a small set of users in a real business scenario.The results show that end users can effectively build their personalized business processes using our approach and interact with them in mobile environment.

SIGNIFICANCE OF PASSIVE MIGRATION IN EVOLUTION OF INSECTICIDE RESISTANCE IN THE MOSQUITO CULEX PIPIENS (DIPTERA:CULICIDAE)

In order to determine the combined effects of migration and gene flow on evolution of insecticide resistance in the mosquito Culex pipiens, four samples were collected in China, among which two were collected along the railway from Beijing to Guangzhou. Bioassay data showed that the resistance levels of the four populations to dichlorvos were high and to parathion moderate as compared with the susceptible strain and there was no significant difference among the four populations to the same organophosphate (OP) insecticide. Starch electrophoresis was done to identify the frequency of known overproduced esterases and to analyze genetic diversity among various populations by electrophoretic polymorphism of five presumably neutral loci. The results indicated that the gene flow between populations existed and the number of effective migrants (Nm) was related to collection geography (Nm from 1.67 to 40.07). In contrast with lower genetic differentiation between two nearby populations (between GZ and ZS, ZZ and SQ) and higher genetic differentiation between two distant populations (between GZ and ZZ), there was a significant and inconsistent difference in the distribution of resistance alleles, A2-B2 when explained only with active migration. This divergent situation could be straightened out when considering passive migration (such as railway transport) which increased the spread of A2-B2 along the railway, i.e., in GZ and ZZ. The resistance alleles, A2-B2, dispersing to around areas by active migration suffered from the limitation of gene flow and the speed of invasion.

Numerical and Experimental Investigation of an Axial Compressor Flow with Tandem Cascade

Basing on a prototype of DCA airfoil and axial displacement overlap of 10% chord,seven kinds of tangential displacements are taken to simulate the flow conditions in tandem cascade with numerical methods to select a better geometry with higher performance.The configuration with tangential displacement b/t=0.83 would gain better flow performance than the others.On this basis,two configurations with tangential displacement b/t=0.67 and 0.83 among several configurations are chosen to take into experimental investigations by using TR-PIV system to capture the flow velocity instantaneously.The configuration with b/t=0.83 is observed a better flow field performance than b/t=0.67.Its injection flow in the gap zone is much stronger,wake zone area of the front and rear blade is smaller and the stream flow is more improved.It shows that the flow performance in experimental investigation is quite in the same trend as the numerical results predict.

Comparative Study of Convective Heat Transfer Performance of Steam and Air Flow in Rib Roughened Channels

A comparative experimental study of heat transfer characteristics of steam and air flow in rectangular channels roughened with parallel ribs was conducted by using an infrared camera. Effects of Reynolds numbers and rib angles on the steam and air convective heat transfer have been obtained and compared with each other for the Reynolds number from about 4,000 to 15,000. For all the ribbed channels the rib pitch to height ratio(p/e) is 10, and the rib height to the channel hydraulic diameter ratio is 0.078, while the rib angles are varied from 90° to 45°.Based on experimental results, it can be found that, even though the heat transfer distributions of steam and air flow in the ribbed channels are similar to each other, the steam flow can obtain higher convective heat transfer enhancement capability, and the heat transfer enhancement of both the steam and air becomes greater with the rib angle deceasing from 90° to 45°. At Reynolds number of about 12,000, the area-averaged Nusselt numbers of the steam flow is about 13.9%, 14.2%, 19.9% and 23.9% higher than those of the air flow for the rib angles of 90°,75°, 60° and 45° respectively. With the experimental results the correlations for Nusselt number in terms of Reynolds number and rib angle for the steam and air flow in the ribbed channels were developed respectively.

Computation of the Viscous Hydrodynamic Forces on a KVLCC2 Model Moving Obliquely in Shallow Water

The viscous hydrodynamic force and moment on ships moving obliquely in shallow water are important for ship navigation safety.In the paper,the viscous flow field around a KVLCC2 model moving obliquely in shallow water is simulated and the hydrodynamic drag,lateral force and yaw moment acting on the hull are obtained by a general purpose computational fluid dynamics(CFD) package FLUENT with shear-stress transport(SST) k—ωturbulence model.The numerical computation is performed at different drift angels and water depths.The numerical results are compared with experimental results,and a good agreement is demonstrated.

Two-flux method for radiation heat transfer in anisotropic gas-particles media

Two-flux method can be used, as a simplification for the radiative heat transfer, to predict heat flux in a slab consisting of gas and particles. In the original two-flux method (Schuster, 1905 and Schwarzschild, 1906), the radiation field was assumed to be isotropic. But for gas-particles mixture in combustion environments, the scatterings of particles are usually anisotropic, and the original two-flux method gives critical errors when ignoring this anisotropy. In the present paper, a multilayer four-flux model developed by Rozé et al. (2001) is extended to calculate the radiation heat flux in a slab containing participating particles and gas mixture. The analytic resolution of the radiative transfer equation in the framework of a two-flux approach is presented. The average crossing parameter ε and the forward scattering ratio ζ are defined to describe the anisotropy of the radiative field. To validate the model, the radiation transfer in a slab has been computed. Comparisons with the exact analytical result of Modest (1993) and the original two-flux model show the exactness and the improvement. The emissivity of a slab containing flyash/CO2/H2O mixture is obtained using the new model. The result is identical with that of Goodwin (1989).

Optimization of Dimples in Microchannel Heat Sink with Impinging Jets-Part B： the Influences of Dimple Height and Arrangement

The combination of a microchannel heat sink with impinging jets and dimples(MHSIJD) can effectively improve the flow and heat transfer performance on the cooling surface of electronic devices with very high heat fluxes. Based on the previous work by analysing the effect of dimple radius on the overall performance of MHSIJD, the effects of dimple height and arrangement were numerically analysed. The velocity distribution, pressure drop, and thermal performance of MHSIJD under various dimple heights and arrangements were presented. The results showed that: MHSIJD with higher dimples had better overall performance with dimple radius being fixed; creating a mismatch between the impinging hole and dimple can solve the issue caused by the drift phenomenon; the mismatch between the impinging hole and dimple did not exhibit better overall performance than a well-matched design.

Peristaltic transport of pseudoplastic fluid in a curved channel with wall properties and slip conditions

Effects of wall properties and slip condition on the peristaltic flow of an incompressible pseudoplastic fluid in a curved channel are studied. Series solution of the governing problem is obtained after applying long wavelength and low Reynolds number approximations. The results are validated with the numerical solutions through the built-in routine for solving nonlinear boundary value problems via software Mathematica. The variations of different parameters on axial velocity are carefully analyzed. Behaviors of embedding parameters on the dimensionless stream function are also discussed. It is noted that the axial velocity and size of trapped bolus increases with an increase in slip parameter. It is also observed that the profiles of axial velocity are not symmetric about the central line of the curved channel which is different from the case of planar channel.

A review on gyrotactic swimmers in turbulent flows

Many marine plankton species are motile and perform daily vertical migrations,traveling across water columns over distances of tens of meters.It is intriguing that these tiny and slow swimmers can travel in a certain direction within a turbulent environment.One way to do that is by exploiting gravitaxis,which is a form of taxis characterised by the directional movement of an organism in response to gravity.Many plankton species are able to generate a gravitational torque(e.g.,due to a nonuniform mass distribution)that reorients them upwards.However,the swimming direction is disturbed by the shearing motions and the velocity fluctuations that characterise oceanic turbulence:these can generate a viscous torque that may destabilize the swimmer.The directed locomotion resulting from the combination of gravitational and viscous torques in a flow is termed gyrotaxis,which is known to lead to a non-uniform spatial accumulation of swimmers in patches or layers.These phenomena depend strongly on the non-linear dynamics that originate from the fluid motions,and the study of gyrotactic swimmers in complex flows is attracting growing attention.Numerical simulations of the Navier-Stokes equations coupled with suitable models of gyrotactic swimmers have proven their capability to provide valuable insight into the dynamical and statistical properties of self-propelled organisms.In this paper,we review recent studies and key findings on gyrotactic swimmers in turbulent flows.First,we introduce the most recent results concerning the orientation and vertical migration of gyrotactic swimmers in isotropic turbulence.Second,we discuss the findings on the accumulation of the swimmers.Last,we review recent progresses concerning the behaviour of gyrotactic swimmers in free-surface turbulence.

The effects of slip condition and fluid flow through a channel multiple stenoses on micropolar of non-uniform cross-section

In this paper, steady incompressible micropolar fluid flow through a non-uniform channel with multiple stenoses is considered. Assuming the stenoses to be mild and using the slip boundary condition, the equations governing the flow of the proposed model are solved, and closed-form expressions for the flow characteristics （resistance to flow and wall shear stress） are derived. The effects of different parameters on these flow characteristics are analyzed. It is observed that both the resistance to the flow and the wall shear stress increase with the heights of the stenoses and the slip parameter; but decrease with the Darcy number, b^rthermore, the effects of the wall exponent parameter, the cross-viscosity coefficient and the micropolar parameter on the flow characteristics are discussed.