14,040 research outputs found

    Automated Configuration Design and Analysis for Service High-Availability

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    The need for highly available services is ever increasing in various domains ranging from mission critical systems to transaction based ones such as online banking. The Service Availability Forum (SAForum) has defined a set of services and related Application Programming Interface (API) specifications to address the growing need of commercial-off-the-shelf high availability solutions. Among these services, the Availability Management Framework (AMF) is the service responsible for managing the high availability of the application services. To achieve this task, an AMF implementation requires a specific logical view of the organization of the application’s services and components, known as an AMF configuration. Any AMF configuration must be compliant to the concepts and constraints defined in the AMF specifications. The process of defining AMF configurations is error prone and requires extensive domain knowledge. Another major issue is being able to analyze the designed AMF configuration to quantify the anticipated service availability. This requires a different set of modeling and analysis skills that system integrators might not necessarily possess. In this dissertation we propose the automation of this process. The premise is to define a generation method within which we embed the domain knowledge and the domain constraints, and by that generating AMF configurations that are valid by construction. We also define an approach for the service availability analysis of AMF configurations. Our method is based on generating an analysis stochastic model that captures the middleware behavior and the application configuration. This model is thereafter solved to quantify the service availability

    A Review of the Monitoring of Market Power The Possible Roles of TSOs in Monitoring for Market Power Issues in Congested Transmission Systems

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    The paper surveys the literature and publicly available information on market power monitoring in electricity wholesale markets. After briefly reviewing definitions, strategies and methods of mitigating market power we examine the various methods of detecting market power that have been employed by academics and market monitors/regulators. These techniques include structural and behavioural indices and analysis as well as various simulation approaches. The applications of these tools range from spot market mitigation and congestion management through to long-term market design assessment and merger decisions. Various market-power monitoring units already track market behaviour and produce indices. Our survey shows that these units collect a large amount of data from various market participants and we identify the crucial role of the transmission system operators with their access to dispatch and system information. Easily accessible and comprehensive data supports effective market power monitoring and facilitates market design evaluation. The discretion required for effective market monitoring is facilitated by institutional independence.Electricity, liberalisation, market power, regulation

    A smart resource management mechanism with trust access control for cloud computing environment

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    The core of the computer business now offers subscription-based on-demand services with the help of cloud computing. We may now share resources among multiple users by using virtualization, which creates a virtual instance of a computer system running in an abstracted hardware layer. It provides infinite computing capabilities through its massive cloud datacenters, in contrast to early distributed computing models, and has been incredibly popular in recent years because to its continually growing infrastructure, user base, and hosted data volume. This article suggests a conceptual framework for a workload management paradigm in cloud settings that is both safe and performance-efficient. A resource management unit is used in this paradigm for energy and performing virtual machine allocation with efficiency, assuring the safe execution of users' applications, and protecting against data breaches brought on by unauthorised virtual machine access real-time. A secure virtual machine management unit controls the resource management unit and is created to produce data on unlawful access or intercommunication. Additionally, a workload analyzer unit works simultaneously to estimate resource consumption data to help the resource management unit be more effective during virtual machine allocation. The suggested model functions differently to effectively serve the same objective, including data encryption and decryption prior to transfer, usage of trust access mechanism to prevent unauthorised access to virtual machines, which creates extra computational cost overhead

    Vehicle re-routing strategies for congestion avoidance

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    Traffic congestion causes driver frustration and costs billions of dollars annually in lost time and fuel consumption. This dissertation introduces a cost-effective and easily deployable vehicular re-routing system that reduces the effects of traffic congestion. The system collects real-time traffic data from vehicles and road-side sensors, and computes proactive, individually tailored re-routing guidance, which is pushed to vehicles when signs of congestion are observed on their routes. Subsequently, this dissertation proposes and evaluates two classes of re-routing strategies designed to be incorporated into this system, namely, Single Shortest Path strategies and Multiple Shortest Paths Strategies. These strategies are firstly implemented in a centralized system, where a server receives traffic updates from cars, computes alternative routes, and pushes them as guidance to drivers. The extensive experimental results show that the proposed strategies are capable of reducing the travel time comparable to a state-of-the-art Dynamic Traffic Assignment (DTA) algorithm, while avoiding the issues that make DTA impractical, such as lack of scalability and robustness, and high computation time. Furthermore, the variety of proposed strategies allows the system to be tuned to different levels of trade-off between re-routing effectiveness and computational efficiency. Also, the proposed traffic guidance system is robust even if many drivers ignore the guidance, or if the system adoption rate is relatively low. The centralized system suffers from two intrinsic problems: the central server has to perform intensive computation and communication with the vehicles in real-time, which can make such solutions infeasible for large regions with many vehicles; and driver privacy is not protected since the drivers have to share their location as well as the origins and destinations of their trips with the server, which may prevent the adoption of such solutions. To address these problems, a hybrid vehicular re-routing system is presented in this dissertation. The system off-loads a large part of the re-routing computation at the vehicles, and thus, the re-routing process becomes practical in real-time. To make collaborative re-routing decisions, the vehicles exchange messages over vehicular ad hoc networks. The system is hybrid because it still uses a server to determine an accurate global view of the traffic. In addition, the user privacy is balanced with the re-routing effectiveness. The simulation results demonstrate that, compared with a centralized system, the proposed hybrid system increases the user privacy substantially, while the re-routing effectiveness is minimally impacted

    Battery storage systems as balancing option in intermittent renewable energy systems - A transdisciplinary approach under the frame of Constructive Technology Assessment

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    Different battery storage technologies are considered as important flexibility option in the face of increasing shares of renewables in the grid. A challenge is to support decision-making by providing a broader perspective on battery technology development, choice, and implementation. The tailored approach in the frame of Constructive Technology Assessment (CTA) in combination with system analysis allows it to explore actor visions and expectations about battery storage and to use this information to provide quantitative information about the consequences of these. Research results combine the perspectives of technology and non-technology related actors (enactors and selectors) to create new and broader knowledge to provide “better” technology. Major implications identified for battery storage are missing business models, uncertain regulations, and doubts about their techno-economic viability. A highlight is a proof that expectations about technology characteristics in orientation to sustainability criteria are settled within concentric perspectives by using the Analytic-Hierarchy-Process (AHP). Enactors focus on economic and technological criteria which reflect the concentric bias of this group. In contrast, selectors perceive environmental and social criteria as more important. The consensus among actors regarding criteria importance is not existent to moderate which indicates that more research is required here. System analysis is used to quantify actor preferences obtained through the AHP. Li-Ion-batteries (LIB), lead-acid-batteries (VRLA), high-temperature-batteries (NaNiCl and NaS), and Vanadium-redox-flowbatteries (VRFB) are evaluated through e.g. life cycle assessment and costing for four different application fields (decentralized storage, wind energy support, primary regulation and energy-time-shift (ETS-includes compressed-air-energy-storage (CAES) and pumped-hydro-storage (PHS)). Preliminary rankings indicate that most LIBs can be recommended for all application areas, wherein decentralized storage is considered to offer the highest potentials for battery storage. VRLA and NaS achieve rather low scores whereas ranking of VRFB is highly dependent on the considered use case. PHS and CAES dominate all assessed energy storage technologies in the ETS application case

    Automatic generation of AMF compliant configurations

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    Nowadays, the demand for robust, reliable, and dependable telecommunication systems is higher than ever. End users expect services to be delivered with minimal to no interruption especially in cases where the effect of service outage can have catastrophic consequences such as loss of human lives and monetary losses. Examples of such applications include air traffic control and navigation systems, or systems that perform money transfer transactions such as VISA. Systems are considered highly available if they are up and running 99.999% of the time. One solution to sustain such availability is for such systems to be deployed on specific middleware that allow the redundancy of the system components to ensure the availability of services they provide. However, most existing platforms are proprietary and platform dependent. The goal of the Service Availability Forum (SAF) is to develop open specifications that aim to standardize the interface between the applications and the middleware from one side and the middleware and the underlying hardware from the other side. SAF specifications have also been developed to allow highly available applications to be built using commercial off-the-shelf components. A key component of SAF is the Availability Management Framework (AMF), which is the middleware part responsible for managing the redundant resources of applications and therefore enables high availability. AMF, however, requires a certain organization and groupings of those components known as an AMF configuration. Creating AMF configurations manually tends to be very difficult, error prone and sometimes impossible when the number of components forming the application and the cluster hosting the application is considerably high, which is the case for most real-world telecommunication systems. In this thesis, we devise a solution for automatically generating AMF compliant configurations for applications. The proposed solution encompasses two techniques that vary depending on the way AMF entities are handled. We have implemented both approaches and applied one of them to a case study to demonstrate the applicability of our solutio

    CHORUS Deliverable 2.1: State of the Art on Multimedia Search Engines

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    Based on the information provided by European projects and national initiatives related to multimedia search as well as domains experts that participated in the CHORUS Think-thanks and workshops, this document reports on the state of the art related to multimedia content search from, a technical, and socio-economic perspective. The technical perspective includes an up to date view on content based indexing and retrieval technologies, multimedia search in the context of mobile devices and peer-to-peer networks, and an overview of current evaluation and benchmark inititiatives to measure the performance of multimedia search engines. From a socio-economic perspective we inventorize the impact and legal consequences of these technical advances and point out future directions of research
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