A Network Recovery Strategy Scheme Based on Network Failure Scenarios and Topologies

Network failures happen frequently. There is a need for recovery mechanisms to reduce service interruption. Recovery mechanismsâ advantages and disadvantages are described extensively based on their characteristics and performances. However, it is more desirable that network recovery strategies are chosen based on failure scenarios and topologies. In this paper, we propose a recovery scheme and focus on networks whose paths and resources from source to destination nodes are computed and negotiated primarily at source nodes, Ingress Label Switched Router (LSR), which are the case for Generalized Multiprotocol Label Switching (GMPLS) networks. Choosing proper network recovery mechanisms depends on many parameters such as distance of failure from source node, degree distribution of nodes, availabilities of alternative paths, and maximum allowed-hopcount increase in alternative paths. Three recovery mechanisms: Haskin, Global and Local Protection are compared with the proposed restoration scheme. By changing parameters on appropriate ranges and by using probability of received data packet at the destination node, e.g. probability of error as one of the performance criteria, we can make a fair judgment on choosing a network strategy by considering available network parameters and topology

Effect of cavities on the behaviour of model pile under axial loading in sand

Presence of cavities in soils is an important area of interest within the field of geotechnical engineering. A better understanding of the behaviour of such soils, particularly in locations where the presence of gypsum deposits is apparent, will have a large impact on the stability of foundations and allows designers and engineers to have a convincing explanation of this phenomenon on the stability of foundations in general. The research offers an experimental investigation to study the performance of axially loaded piles embedded in sandy soils with cavities. The experimental study comprised a full laboratory testing programme carried out on small scale piles embedded in predetermined cavities within a soil mass. The experimental model has the capability to investigate the effect of different cavity locations on the ultimate pile resistances. Thirteen cavity locations were chosen to study their influence on the ultimate carrying load of single pile. It was concluded that the maximum ultimate carrying load of the pile is reduced by the presence of the cavity within the soil mass. This reduction varies according to the cavity location. The effect of cavity’s presence on the ultimate bearing capacity of pile ranged from 0% to 30.82% for side cavities, while the range of reduction factor for cavities under the pile tip is from 31.58% to 43.4%. The reduction in pile capacity increases when the cavity is closer to the pile. Also, pile settlement value without cavity is less than the settlement of the same pile with cavity

Modelling the response of single passive piles subjected to lateral soil movement using PLAXIS

Response of single pile subjected to lateral displacements of soil mass using 3D finite element software (PLAXIS) is studied. Embedded pile feature in which the pile composed of beam elements with special interface elements to represent pile-soil interaction is used. The Mohr–Coulomb elastic–plastic constitutive model was employed for the soil stress-strain behaviour. A good agreement between laboratory and predicted results is observed in the validation analysis. A parametric study was conducted to investigate the influence of soil Young's modulus and soil movement profile on the response of single "passive pile". The software results revealed that the distribution of bending moment along the pile length vary considerably and was in a very good agreement with the real pile behaviour when adopting a variation of soil elastic modulus with depth instead of choosing a constant value

Optimization of the OpenFlow Controller in Wireless Environments for Enhancing Mobility

OpenRoads or OpenFlow Wireless is an open-source platform for deploying an innovative and realistic strategy for different services in wireless networks. It provides a wireless extension for OpenFlow. It is developed to support existing Wireless Local Area Networks (WLANs) and Worldwide Interoperability for Microwave Access (WiMAX) networks. It can provide several mobility managers and run them concurrently in the network including hard handover, informed handover, n-casting and Hoolock. However, the provided mobility support for flow-based routing, where flows of one source taking different paths through multiple wireless access points or base stations, is not simple and hard to be deployed in the traditional routing algorithms. This paper proposes an intelligent mobility enhancement control and then develops an algorithm to decide which neighbor switches need to be selected for the installation of new flow entries and to allocate the appropriate idle-timeout for the selected switches. The proposed approach provides a simple solution to solve the user mobility problem in wireless OpenFlow environments which can handle the fast migration of user addresses (e.g. IP addresses) between several wireless access points and base stations. This approach leads to improvement in the end users' experience

Developing an application based on OpenFlow to enhance mobile IP networks

Mobile Internet Protocol (IP) has been developed to maintain permanent IP addresses for mobile users while they are moving from one point to another where the Mobile Terminal (MT) device will have two IP addresses: a static home address and a care-of address which will be changed and re-attached at each point of the movement of the MT. However, a location update message is required to be sent to the home agent for each new connection. This will potentially increase the handoff latency and leads to high load on the global Internet. This paper presents the concepts and the challenges of Mobile IP networks and then proposes the use of OpenFlow approach as an alternate transport mechanism to perform routing and to provide network connectivity for Mobile IP networks. The proposed application determines calculations and reroutes the subsequent packets. OpenFlow aims to optimize routing path and handoff performance by using controller's application and exchanges controllers' information. © 2013 IEEE

Lowering of ground state induced by core-shell structure in strontium titanate

International audienc

Some Numerical Methods For Solving Fractional Parabolic Partial Differential Equations

The aim of this paper isto approximate the solution offractionalparabolicpartial differential equations using two numerical methods which areBellman's method (make use of Lagrange interpolation formula) and the methodof lines. Fractional Parabolic partial differential equations are transformed to asystem of first order ordinary differential equations that are solved using a Runge-Kutta method. An illustrative example using thesemethodsare also presented andcompared with the exact solution

Multi-Service Group Key Management for High Speed Wireless Mobile Multicast Networks

YesRecently there is a high demand from the Internet Service Providers to transmit multimedia services over high speed wireless networks. These networks are characterized by high mobility receivers which perform frequent handoffs across homogenous and heterogeneous access networks while maintaining seamless connectivity to the multimedia services. In order to ensure secure delivery of multimedia services to legitimate group members, the conventional cluster based group key management (GKM) schemes for securing group communication over wireless mobile multicast networks have been proposed. However, they lack efficiency in rekeying the group key in the presence of high mobility users which concurrently subscribe to multiple multicast services that co-exist in the same network. This paper proposes an efficient multi-service group key management scheme (SMGKM) suitable for high mobility users which perform frequent handoffs while participating seamlessly in multiple multicast services. The users are expected to drop subscriptions after multiple cluster visits hence inducing huge key management overhead due to rekeying the previously visited cluster keys. The already proposed multi-service SMGKM system with completely decentralised authentication and key management functions is adopted to meet the demands for high mobility environment with the same level of security. Through comparisons with existing GKM schemes and simulations, SMGKM shows resource economy in terms of reduced communication and less storage overheads in a high speed environment with multiple visits

Using an ICN Approach to Support Multiple Controllers in OpenFlow

Abstract — Information Centric Networking (ICN) is an innovative direction for next generation networks. It is a concept of networking paradigm which is considered as a new technique for future search activities. ICN is based on caching contents in several nodes and replicating these contents. It provides contents requested by users from the nearest node instead of creating a communication channel between sender and receiver just for calling information. This paper aims to scale OpenFlow network in traffic engineering by reducing number of transactions, predicting and pre-populating flow entries using the ICN approach. In addition, the paper shows the advantages of implementing ICN designs within OpenFlow. The proposed approach aims to implement ICN concepts to enhance OpenFlow network. This will enable the deployment of networking solutions in the existing network infrastructure and will lead to more flexibility in OpenFlow network. In addition, OpenFlow will have a global management view for all connected networks managed by different controllers. The proposed solution can fulfill current management and utilization of network demands. The paper then debates the implementation of ICN’s design and features based on Software Defined Networking (SDN)

Birth prevalence of non-syndromic orofacial clefts in Saudi Arabia and the effects of parental consanguinity

Objectives: To describe the characteristics and prevalence of non-syndromic orofacial clefting (NSOFC) and assess the effects of parental consanguinity on NSOFC phenotypes in the 3 main cities of Saudi Arabia. Methods: All infants (114,035) born at 3 referral centers in Riyadh, and 6 hospitals in Jeddah and Madinah between January 2010 and December 2011 were screened. The NSOFC cases (n=133) were identified and data was collected through clinical examination and records, and information on consanguinity through parent interviews. The diagnosis was confirmed by reviewing medical records and contacting the infants’ pediatricians. Control infants (n=233) matched for gender and born in the same hospitals during the same period, were selected. Results: The prevalence of NSOFC was 1.07/1000 births in Riyadh, and 1.17/1000 births overall; cleft lip (CL) was 0.47/1000 births, cleft lip and palate (CLP) was 0.42/1000 births, and cleft palate (CP) was 0.28/1000 births. Cleft palate was significantly associated with consanguinity (p=0.047, odds ratio: 2.5, 95% confidence interval: 1 to 6.46), particularly for first cousin marriages. Conclusion: The birth prevalence of NSOFC in Riyadh alone, and in the 3 main cities of Saudi Arabia were marginally lower than the mean global prevalence. While birth prevalence for CLP was comparable to global figures, the CL:CLP ratio was high, and only CP was significantly associated with consanguinity