30,254 research outputs found

    Regional integrated infrastructure scoping study

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    The purpose of the study is to consider how the Region should take infrastructure forward in an integrated way at a strategic level and to help scope further work to inform the RSS 2009 Update. It is envisaged that this scoping study is the first part of a major work stream for the Assembly to enable infrastructure to influence future locational decisions and develop a better understanding of the impact of higher levels of growth on the Region’s infrastructure

    A Survey on the Contributions of Software-Defined Networking to Traffic Engineering

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    Since the appearance of OpenFlow back in 2008, software-defined networking (SDN) has gained momentum. Although there are some discrepancies between the standards developing organizations working with SDN about what SDN is and how it is defined, they all outline traffic engineering (TE) as a key application. One of the most common objectives of TE is the congestion minimization, where techniques such as traffic splitting among multiple paths or advanced reservation systems are used. In such a scenario, this manuscript surveys the role of a comprehensive list of SDN protocols in TE solutions, in order to assess how these protocols can benefit TE. The SDN protocols have been categorized using the SDN architecture proposed by the open networking foundation, which differentiates among data-controller plane interfaces, application-controller plane interfaces, and management interfaces, in order to state how the interface type in which they operate influences TE. In addition, the impact of the SDN protocols on TE has been evaluated by comparing them with the path computation element (PCE)-based architecture. The PCE-based architecture has been selected to measure the impact of SDN on TE because it is the most novel TE architecture until the date, and because it already defines a set of metrics to measure the performance of TE solutions. We conclude that using the three types of interfaces simultaneously will result in more powerful and enhanced TE solutions, since they benefit TE in complementary ways.European Commission through the Horizon 2020 Research and Innovation Programme (GN4) under Grant 691567 Spanish Ministry of Economy and Competitiveness under the Secure Deployment of Services Over SDN and NFV-based Networks Project S&NSEC under Grant TEC2013-47960-C4-3-

    Improving the resilience of post-disaster water distribution systems using a dynamic optimization framework

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    The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Improving the resilience of water distribution systems (WDSs) to handle natural disasters (e.g., earthquakes) is a critical step towards sustainable urban water management. This requires the water utility to be able to respond quickly to such disaster events and in an organized manner, to prioritize the use of available resources to restore service rapidly whilst minimizing the negative impacts. Many methods have been developed to evaluate the WDS resilience, but few efforts are made so far to improve resilience of a post-disaster WDS through identifying optimal sequencing of recovery actions. To address this gap, a new dynamic optimization framework is proposed here where the resilience of a post-disaster WDS is evaluated using six different metrics. A tailored Genetic Algorithm is developed to solve the complex optimization problem driven by these metrics. The proposed framework is demonstrated using a real-world WDS with 6,064 pipes. Results obtained show that the proposed framework successfully identifies near-optimal sequencing of recovery actions for this complex WDS. The gained insights, conditional on the specific attributes of the case study, include: (i) the near-optimal sequencing of recovery strategy heavily depends on the damage properties of the WDS, (ii) replacements of damaged elements tend to be scheduled at the intermediate-late stages of the recovery process due to their long operation time, and (iii) interventions to damaged pipe elements near critical facilities (e.g., hospitals) should not be necessarily the first priority to recover due to complex hydraulic interactions within the WDS

    Harmonizing Climate Change Mitigation and Adaptation in Transportation and Land-Use Planning in California Cities

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    Abstract: Recent extreme weather events in California—wildfires, drought, and flooding—make abundantly clear the need to plan effective responses to both the causes and the consequences of climate change. A central challenge for climate planning efforts has been identifying transportation and land-use (TLU) strategies that simultaneously reduce greenhouse gas emissions (“mitigation”) and adapt communities so that they will be less affected by the adverse impacts of climate change (“adaptation”). Sets of policies that collectively address both mitigation and adaptation are known as “integrated actions.” This study explores municipal climate planning in California to determine whether cities incorporate integrated actions into their plans, assess the potential drivers of conflict between mitigation and adaptation in municipal plans, and identify ways the State of California can help cities more effectively incorporate integrated actions. The study methods consisted of a detailed analysis of climate planning documents from 23 California cities with particularly long histories of climate planning, plus interviews with 25 local, regional, and state officials who work on municipal climate planning. The authors found that some cities did adopt packages of integrated actions, and, promisingly, two cities with recently updated climate plans explicitly focused on the need for integrated actions. However, most cities addressed climate mitigation and adaptation in separate efforts, potentially reducing synergies between the two types of action and even creating conflicts. Since the first generation of climate action plans focused primarily on mitigation of greenhouse gases (GHGs), adaptation strategies have not yet been effectively or fully combined into mitigation plans in many cities. Also, a cross-comparison of plan content and interview data suggests that cities often had sets of policies that could potentially create conflicts—mitigation policies that would undermine adaptation capacity, and vice versa. In addition, where a city did adopt integrated actions, these efforts are typically not labeled as such, nor do the policies appear within the same policy document. The study findings suggest promising steps that both municipal and state governments can take to support integrated TLU actions at the local level. For example, cities can proactively link the content in climate mitigation and adaptation plans—a process that will require building the capacity for cross-collaboration between the various departments in charge of developing, implementing, and monitoring climate-related plans. As for the state government, it can provide funding specifically for planning and implementing integrated actions, offer technical support to help municipalities adopt programs and projects that produce integrated mitigation and adaptation benefits, and fund research in the area of integrated actions

    Self-healing in unattended wireless sensor networks

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    Wireless sensor networks (WSNs) appeal to a wide range of applications that involve the monitoring of various physical phenomena. However, WSNs are subject to many threats. In particular, lack of pervasive tamper-resistant hardware results in sensors being easy targets for compromise. Having compromised a sensor, the adversary learns all the sensor secrets, allowing it to later encrypt/decrypt or authenticate messages on behalf of that sensor. This threat is particularly relevant in the novel unattended wireless sensor networks (UWSNs) scenario. UWSNs operate without constant supervision by a trusted sink. UWSN?s unattended nature and increased exposure to attacks prompts the need for special techniques geared towards regaining security after being compromised. In this article, we investigate cooperative self-healing in UWSNs and propose various techniques to allow unattended sensors to recover security after compromise. Our techniques provide seamless healing rates even against a very agile and powerful adversary. The effectiveness and viability of our proposed techniques are assessed by thorough analysis and supported by simulation results. Finally, we introduce some real-world issues affecting UWSN deployment and provide some solutions for them as well as a few open problems calling for further investigation

    On Resilient Control of Nonlinear Systems under Denial-of-Service

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    We analyze and design a control strategy for nonlinear systems under Denial-of-Service attacks. Based on an ISS-Lyapunov function analysis, we provide a characterization of the maximal percentage of time during which feedback information can be lost without resulting in the instability of the system. Motivated by the presence of a digital channel we consider event-based controllers for which a minimal inter-sampling time is explicitly characterized.Comment: 7 pages, 1 figur
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