Dynamic service provisioning using GRIA SLAs

Service Level Agreements (SLA) include quality of service (QoS) constraints and bounds that have to be honoured by the service provider. To maximise the Service Provider revenue while satisfying the QoS requirements of the agreed SLAs it is important to be able to per- form a dynamic distribution of the service provider resources between the services and SLAs. This distribution should be based on the current status and predicted evolution of the QoS characteristics. This paper de- scribes the experiences managing SLA obligations from a service provider perspective in a scenario where dynamic deployment of services can be undertaken. The main issues faced to deal with the management of SLAs in this context are detailed. The adopted solution, based on GRIA (a Service Oriented Architecture framework) is discussed

Dynamic Service Provisioning Using GRIA SLAs

Abstract. Service Level Agreements (SLA) include quality of service (QoS) constraints and bounds that have to be honoured by the service provider. To maximise the Service Provider revenue while satisfying the QoS requirements of the agreed SLAs it is important to be able to perform a dynamic distribution of the service provider resources between the services and SLAs. This distribution should be based on the current status and predicted evolution of the QoS characteristics. This paper describes the experiences managing SLA obligations from a service provider perspective in a scenario where dynamic deployment of services can be undertaken. The main issues faced to deal with the management of SLAs in this context are detailed. The adopted solution, based on GRIA (a Service Oriented Architecture framework) is discussed. Key words: SLA management, dynamic provisioning

On the Privacy of Counting Bloom Filters Under a Black-Box Attacker

7 páginas, 8 figurasCounting Bloom Filters (CBFs) are approximate membership checking data structures, and it is normally believed that at most an approximate reconstruction of the underlying set can be derived when interacting with a CBF. This paper decisively refutes this assumption. In a recent paper, we considered the privacy of CBFs when the attacker has access to the implementation details and thus, it sees the filter as a white-box. In that setting, we showed that the attacker may be able to extract the elements stored in the filter when the number of false positives over the entire universe is not significantly larger than the number of elements stored in the filter. In this work, we consider a black-box attacker that can only perform user interactions on the CBF to insert, remove and query elements with no knowledge of the filter implementation details. We show that even in this case, an attacker may be able to extract information from the filter at the cost of using more complex and time-consuming attack algorithms. The proposed algorithms have been implemented and compared with the white-box attack, showing that in most cases, almost the same information can be extracted from the filter

Radiation Hardened Digital Direct Synthesizer With CORDIC for Spaceborne Applications

The Coordinate Rotation Digital Computer algorithm (CORDIC) is a simple mechanism to compute a set of elementary functions, such as trigonometric functions, using fixed-point devices. It is widely adopted, also in applications running in harsh environments such as space, where radiation is a cause of errors in nanoelectronic devices. A single event upset in a configuration bit of a Field Programmable Gate Array (FPGA) can completely change the behavior of the implemented circuit, so it is important to detect and reconfigure the FPGA when this happens. Dual modular redundancy is the typical method to detect errors in electronic circuits, but it has an important overhead in area and power consumption and it does not provide any additional functionality apart from the activation of the FPGA reconfiguration trigger in presence of error. This paper presents two ad-hoc techniques to protect the Digital Direct Synthesizer with CORDIC when it is implemented into an FPGA, with limited overhead in terms of area and power consumption when compared with the traditional solution. The first solution slightly increases the percentage of undetected errors, about 11%, reducing to almost half the area overhead of the circuit. The second solution introduces a trade-off between the percentage of error detection and the precision of the trigonometric output of the CORDIC by means of a polymorphic structure with lower area resources than the existing solutions. This last proposal allows the system to increase the precision of the digital synthesis signal under absence of errors or to activate the error protection in scenarios with external disturbances such as radiation.Depto. de Arquitectura de Computadores y AutomáticaFac. de InformáticaTRUEpu

Reducing the Impact of Defects in Quantum-Dot Cellular Automata (QCA) Approximate Adders at Nano Scale

Quantum-dot Cellular Automata (QCA) has been studied for some time as a candidate to replace traditional CMOS circuits. QCA circuits are implemented using majority-logic gates and inverters as primitive elements. Different types of defects affecting QCA during synthesis and manufacturing have been identified. Due to the use of the majority logic gate as the main building block of logic designs, the probability and impact of a defect affecting this type of element is significant. The effect can be translated into a change of the boolean expression implemented by the gate. QCA Approximate adders have been proposed for image processing and other applications. This paper analyzes the effect of QCA majority gate defects in the processing of images when using approximate adders. This is done by evaluating the variation in the value of common error distance metrics in the presence of defects. Mitigation of these defects by combining approximate and exact adders and selective introduction of fault-tolerant majority gates in different bits is analyzed. The technique achieves a reduction of around 75% of the average normalized mean error distance (NMED). Specific image-based metrics such as PSNR and SSIM are also evaluated in two different experiments, with an increase of up to 225% and 226% respectively. The increase in area is limited to around 40%.Depto. de Arquitectura de Computadores y AutomáticaFac. de InformáticaTRUEpu

Erratum to: Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition) (Autophagy, 12, 1, 1-222, 10.1080/15548627.2015.1100356

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