@article {18566,
	title = {Impact of Failure Prediction on Availability: Modeling and Comparative Analysis of Predictive and Reactive Methods},
	journal = {IEEE Transactions on Dependable and Secure Computing},
	year = {2018},
	pages = {1-1},
	abstract = {Predicting failures and acting proactively have a potential to improve availability as a correct prediction and a successful mitigation may bring a reward resulting in decrease of downtime and availability improvement. But, conversely, each incorrect prediction may introduce additional downtime (penalty). Therefore, depending on the quality of prediction and the system parameters, predictive fault-tolerance methods may improve or may degrade availability in comparison to the reactive ones. We first derive taxonomies of fault-tolerant techniques and policies to differentiate between reactive and proactive policies that are further classified as systematic and predictive. To evaluate whether a predictive policy improves availability or not, we derive an analytical model for availability quantification. We use Markov chains to extend steady-state availability equation to include: precision and recall, penalty and reward, mitigation success probability and potential failure rate increase due to the prediction load. We also derive A-measure to optimize failure prediction for increasing availability. In our conclusion, precision and recall have comparable impact on availability as changing MTTF and MTTR. To validate the model we also simulate and analyze availability of a virtualized server with exponential distribution of failure and repair rates.},
	keywords = {Analytical models, availability, Computational modeling, failure, fault tolerance, Fault tolerant systems, Mathematical model, modeling, Optimization, prediction, predictive, Predictive models, proactive, Servers},
	issn = {1545-5971},
	doi = {10.1109/TDSC.2018.2806448},
	author = {Kaitovi{\'c}, Igor and Malek, Miroslaw}
}
@conference {17729,
	title = {A Model for the Evaluation of User-Perceived Service Properties},
	booktitle = {International Symposium on Parallel Distributed Processing, Workshops and Phd Forum (IPDPSW)},
	year = {2013},
	month = {May},
	publisher = {IEEE Computer Society},
	organization = {IEEE Computer Society},
	address = {Boston, Massachusetts, USA},
	abstract = {An ever-increasing number of both functional and non-functional requirements has resulted in growing system complexity which demands new solutions in system modeling and evaluation. As a remedy, service-oriented architecture (SOA) offers services as basic building elements of system design. Service dependability is highly dependent on the properties of the underlying information and communications technology (ICT) infrastructure. This is especially true for the user-perceived dependability of a specific pair service client and provider as every pair may utilize different ICT components. We provide a model for the description of ICT components and their non-functional properties based on the Unified Modeling Language (UML). Given a service description, a network topology model and a pair service client and provider, we propose a methodology to automatically identify relevant ICT components and generate a user-perceived service infrastructure model (UPSIM). We demonstrate the feasibility of the methodology by applying it to parts of the service network infrastructure at Universit{\`a} della Svizzera italiana, Switzerland. We then show how this methodology can be used to facilitate user-perceived service dependability analysis.},
	keywords = {availability, design engineering, metamodeling, modeling, object oriented modeling, quality of service (QoS), service dependability, service network management, service networks},
	isbn = {978-0-7695-4979-8},
	doi = {10.1109/IPDPSW.2013.163},
	url = {http://andreas-dittrich.eu/2013/03/a-model-for-the-evaluation-of-user-perceived-service-properties},
	author = {Dittrich, Andreas and Kaitovi{\'c}, Igor and Murillo, Cristina and Rezende, Rafael}
}
@inbook {17731,
	title = {Model-Driven Evaluation of User-Perceived Service Availability},
	booktitle = {Dependable Computing},
	series = {Lecture Notes in Computer Science},
	volume = {7869},
	year = {2013},
	month = {May},
	pages = {39-53},
	publisher = {Springer Berlin Heidelberg},
	organization = {Springer Berlin Heidelberg},
	abstract = {Service-oriented architecture (SOA), which proposes services as basic building elements of system design, has emerged as an approach to master growing system complexity. However, it remains difficult to evaluate dependability of such distributed and heterogeneous functionality as it depends highly on the properties of the enabling information and communications technology (ICT) infrastructure. Moreover, every specific pair service client and provider can utilize different ICT components, constituting for the user-perceived view of a service. We provide a model-driven methodology to automatically create reliability block diagrams of such views. Given a service description, a network topology model and a pair service client and provider, it identifies relevant ICT components and generates a user-perceived service availability model (UPSAM). We then use this UPSAM to calculate the steady-state availability of different views on an examplary mail service deployed in the network infrastructure of University of Lugano.},
	keywords = {availability, design engineering, modeling, object oriented modeling, quality of service (QoS), service dependability, service network management, service networks},
	issn = {978-3-642-38788-3},
	doi = {10.1007/978-3-642-38789-0_4},
	url = {http://andreas-dittrich.eu/2013/04/model-driven-evaluation-of-user-perceived-service-availability},
	author = {Dittrich, Andreas and Rezende, Rafael},
	editor = {Vieira, Marco and Cunha, Jo{\~a}o Carlos}
}
@inbook {18089,
	title = {Systems Engineering for Assessment of Virtual Power System Implementations},
	booktitle = {Artificial Intelligence Applications and Innovations},
	series = {9th IFIP WG 12.5 International Conference, AIAI 2013, Paphos, Cyprus, September 30 {\textendash} October 2, 2013, Proceedings},
	volume = {412},
	year = {2013},
	pages = {667-676},
	publisher = {Springer Berlin Heidelberg},
	organization = {Springer Berlin Heidelberg},
	abstract = {In this work we present an adoption of systems engineering methodology for design and assessment of a Virtual Power System (VPS). The VPS has been defined as an aggregation of distributed energy resources, consumers and storages which can operate autonomously, and is presented to the power system as a single unit in technical and commercial terms. The complexity of these critical systems is tackled by means of systems engineering. We have applied our approach in scope of a research project AlpEnergy.},
	keywords = {assessment, modeling, SysML, systems engineering, VPS},
	isbn = {978-3-642-41141-0},
	issn = {1868-4238},
	doi = {10.1007/978-3-642-41142-7_67},
	author = {Lukovi{\'c}, Slobodan and Kaitovi{\'c}, Igor}
}
@conference {17846,
	title = {User-Perceived Instantaneous Service Availability Evaluation},
	booktitle = {19th Pacific Rim International Symposium on Dependable Computing (PRDC)},
	year = {2013},
	month = {12/2013},
	publisher = {IEEE Computer Society},
	organization = {IEEE Computer Society},
	address = {Vancouver, British Columbia, Canada},
	abstract = {Today{\textquoteright}s businesses rely ever more on dependable service provision deployed on information and communications technology (ICT) infrastructures. Service dependability is highly influenced by the individual infrastructure component properties. Combining these properties for consistent dependability analysis is challenging as every service requester might use a different set of components during service usage, constituting the user-perceived view on a service. This paper presents a methodology to evaluate user-perceived instantaneous service availability. It uses three input models: (1) The ICT infrastructure, with failure rates, repair rates and deployment times of all components, (2) an abstract description of complex hierarchical services, (3) a mapping that contains concrete ICT components for the service pair requester and provider, as well as their existing replicas, and a duration of usage. The methodology then automatically generates an availability model from those parts of the ICT infrastructure needed during provision for the specified pair. To calculate instantaneous availability, the age of the ICT components, the order and time of their usage during service provision are taken into account. The methodology supports generation of different availability models, we demonstrate this by providing reliability block diagrams and fault-trees. We demonstrate the feasibility of the methodology by applying it to parts of the network infrastructure of Universit{\`a} della Svizzera italiana, Switzerland.},
	keywords = {availability, Client-server systems, Distributed computing, fault tolerance, modeling},
	doi = {10.1109/PRDC.2013.49},
	url = {http://andreas-dittrich.eu/2013/08/user-perceived-instantaneous-service-availability-evaluation},
	author = {Rezende, Rafael and Dittrich, Andreas and Malek, Miroslaw}
}
@conference {85.MuSaParma08,
	title = {Code Generation from Statecharts: Simulation of Wireless Sensor Networks},
	booktitle = {Proceedings of DSD08},
	year = {2008},
	month = {September},
	address = {Parma, Italy},
	abstract = {Automatic generation of code starting from lightweight modeling languages such as UML is by now a widely adopted approach. In particular generation of executable SystemC models starting from StateCharts and other UML diagrams represents a promising research field. While RTL SystemC appears better suited for matching the StateCharts formalism (being intrinsically clocked), performances of the generated code suffer from the heavy overhead induced by time management, specially when the number of concurrent processes is high. In this paper we present a methodology that allows applying a solution mixing event based and clock-driven approach. More specifically, clock-driven simulation is activated only when the configuration of the system is identified to be evolving. When no events are present this fact is also detected (together with the interval of absence of events) so that no simulation is performed although the clock runs on. This solution is particularly suited for low duty cycle systems, as, e.g. when simulating Wireless Sensor Networks (WSN); in such instances, speedup of the generated code has been found to be well over two orders of magnitude. Application of the technique to the generation of a power simulator for the IEEE 802.15.4 networking protocol is used as a test case.},
	keywords = {low power design, modeling, protocol, wireless sensor networks},
	doi = {http://dx.doi.org/10.1109/DSD.2008.106},
	author = {Mura, Marcello and Sami, Mariagiovanna}
}
@conference {79.Ptsbrg,
	title = {Modelling the Power Cost of Security in Wireless Sensor Networks : the Case of 802.15.4},
	booktitle = {Proceedings of IEEE ICT08},
	year = {2008},
	month = {June},
	address = {Saint Petersburg, Russia},
	abstract = {Pervasive applications and in particular Wireless Sensors Networks have very strict requirements in terms of power consumption. It is well known that radio activity is very expensive in terms of energy; we show here that intensive processing activities (as security) represent a major contribution to power budget. In this paper we extend our methodology for analyzing the impact of Security related operations on power consumption and optimizing it. The analysis is based on experimental data and was validated with measurements on a real platform.},
	keywords = {low power design, modeling, protocol, wireless sensor networks},
	doi = {http://dx.doi.org/10.1109/ICTEL.2008.4652616},
	author = {Mura, Marcello and Fabbri, Fabio and Sami, Mariagiovanna}
}
@conference {49.MuPaNeSaFa07,
	title = {Power Modeling and Power Analysis for IEEE 802.15.4: a Concurrent State Machine Approach},
	booktitle = {Proceedings of CCNC 2007},
	year = {2007},
	month = {January 11-13},
	address = {Las Vegas, USA},
	abstract = {802.15.4 is a recent low-rate/low-power standard for wireless personal area and sensor networks. Its simple infrastructure, intermediate range and good power performance make it a candidate for applications that require a reasonably low throughput but a very high device lifetime and power efficiency. An experimental power analysis of an 802.15.4 implementation is carried out, providing a detailed power model of the protocol based on concurrent state machines; resulting power model is then used to generate a customized simulator. The model has been validated through a set of experiments and provides good accuracy; results are discussed, considering in particular use of the model as a basis for subsequent optimizations on 802.15.4 networks.},
	keywords = {low power design, modeling, wireless sensor networks},
	doi = {http://dx.doi.org/10.1109/CCNC.2007.135},
	author = {Mura, Marcello and Paolieri, Marco and Negri, Luca and Fabbri, Fabio and Sami, Mariagiovanna}
}
@conference {71.pisa,
	title = {Ultra-low power optimizations for the IEEE 802.15.4 networking protocol},
	booktitle = {proceedings of MASS},
	year = {2007},
	month = {October},
	abstract = {A main challenge to be tackled in the area of Wireless Sensors Networks (WSN)s is related to the limited amount of energy available and the requirements in terms of lifetime. IEEE 802.15.4 is a recent low-rate/lowpower standard for wireless personal area and sensor networks. Its simple infrastructure, intermediate range and reasonable power performance make it a candidate for a wide range of applications that require a low throughput but a reasonable device lifetime and consequently a certain power efficiency. Anyway there are some main inefficiencies of the protocol that limit its power performance and cause unnecessary power waste in some situations. In this paper these limitations of the standard in terms of power performance are investigated. Possible optimizations that can be achieved with minimal or null changes on available 802.15.4 compliant hardware platforms are suggested.},
	keywords = {low power design, modeling, protocol, wireless sensor networks},
	doi = {http://dx.doi.org/10.1109/MOBHOC.2007.4428630},
	author = {Mura, Marcello}
}
