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HYPE with stochastic events.
 In: QAPL 2011, EPTCS 57,
, 2011
"... The process algebra HYPE was recently proposed as a finegrained modelling approach for capturing the behaviour of hybrid systems. In the original proposal, each flow or influence affecting a variable is modelled separately and the overall behaviour of the system then emerges as the composition of ..."
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Cited by 6 (2 self)
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The process algebra HYPE was recently proposed as a finegrained modelling approach for capturing the behaviour of hybrid systems. In the original proposal, each flow or influence affecting a variable is modelled separately and the overall behaviour of the system then emerges as the composition of these flows. The discrete behaviour of the system is captured by instantaneous actions which might be urgent, taking effect as soon as some activation condition is satisfied, or nonurgent meaning that they can tolerate some (unknown) delay before happening. In this paper we refine the notion of nonurgent actions, to make such actions governed by a probability distribution. As a consequence of this we now give HYPE a semantics in terms of TransitionDriven Stochastic Hybrid Automata, which are a subset of a general class of stochastic processes termed Piecewise Deterministic Markov Processes.
PCTMC models of wireless sensor network protocols
 in Proc. UK Performance Engineering Workshop (UKPEW
, 2012
"... Abstract. Wireless Sensor Networks (WSNs) consist of a large number of spatially distributed embedded devices (nodes), which communicate with one another via radio. Over the last decade improvements in hardware and a steady decrease in cost have encouraged the application of WSNs in areas such as in ..."
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Cited by 4 (3 self)
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Abstract. Wireless Sensor Networks (WSNs) consist of a large number of spatially distributed embedded devices (nodes), which communicate with one another via radio. Over the last decade improvements in hardware and a steady decrease in cost have encouraged the application of WSNs in areas such as industrial control, security and environmental monitoring. However, despite increasing popularity, the design of endtoend software for WSNs is still an expert task since the choice of middleware protocols heavily influences the performance of resourceconstrained WSNs. As a consequence, WSN designers resort to discrete event simulation prior to deploying networks. While such simulations are reasonably accurate, they tend to be computationally expensive to run, especially for large networks. This particularly limits the number of distinct protocol configurations that engineers can test in advance of construction and hence their final setup may be suboptimal. To mitigate this effect we discuss how highly efficient meanfield techniques can be brought to bear on models of wireless sensor networks. In particular, we consider the practical modelling issues involved in constructing appropriately realistic Population CTMC (PCTMC) models of WSN protocols.
Hybrid performance modelling of opportunistic networks
 In: QAPL 2012, EPTCS 85
, 2012
"... We demonstrate the modelling of opportunistic networks using the process algebra stochastic HYPE. Network traffic is modelled as continuous flows, contact between nodes in the network is modelled stochastically, and instantaneous decisions are modelled as discrete events. Our model describes a netw ..."
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We demonstrate the modelling of opportunistic networks using the process algebra stochastic HYPE. Network traffic is modelled as continuous flows, contact between nodes in the network is modelled stochastically, and instantaneous decisions are modelled as discrete events. Our model describes a network of stationary video sensors with a mobile ferry which collects data from the sensors and delivers it to the base station. We consider different mobility models and different buffer sizes for the ferries. This case study illustrates the flexibility and expressive power of stochastic HYPE. We also discuss the software that enables us to describe stochastic HYPE models and simulate them.
A COMPOSITIONAL APPROACH FOR MODELING AND SIMULATION OF BIOMOLECULAR SYSTEMS
"... The simulation of biological systems is a challenge to modeling methodologies. Living entities are supported by a complex hierarchical network of chemical reactions. The accurate representation of organisms require the use of stochastic chemical equations (SCE) organized into compartments in order t ..."
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The simulation of biological systems is a challenge to modeling methodologies. Living entities are supported by a complex hierarchical network of chemical reactions. The accurate representation of organisms require the use of stochastic chemical equations (SCE) organized into compartments in order to reflect the organization into cells, tissues and organs. In this paper we introduce a modeling and simulation framework based on the Heterogeneous Flow System Specification formalism (HFSS). HFSS provides an hybrid representation of dynamic systems, being able to describe sampled and discrete event systems. These features enable a modular representation of stochastic chemical reactions. In particular, we show that SCE require only two types of HFSS models defined in this paper: molecule holders, and chemical reactors. We provide a description of a HFSS implementation based on pluggable software units (PUs), a componentbased framework that supports the development of SCE libraries. 1
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"... Hybrid performance modelling of opportunistic networks ..."