Event Stream Processing with Multiple Threads

Current runtime verification tools seldom make use of multi-threading to speed up the evaluation of a property on a large event trace. In this paper, we present an extension to the BeepBeep 3 event stream engine that allows the use of multiple threads during the evaluation of a query. Various parallelization strategies are presented and described on simple examples. The implementation of these strategies is then evaluated empirically on a sample of problems. Compared to the previous, single-threaded version of the BeepBeep engine, the allocation of just a few threads to specific portions of a query provides dramatic improvement in terms of running time

Cooperative Epistemic Multi-Agent Planning for Implicit Coordination

Epistemic planning can be used for decision making in multi-agent situations with distributed knowledge and capabilities. Recently, Dynamic Epistemic Logic (DEL) has been shown to provide a very natural and expressive framework for epistemic planning. We extend the DEL-based epistemic planning framework to include perspective shifts, allowing us to define new notions of sequential and conditional planning with implicit coordination. With these, it is possible to solve planning tasks with joint goals in a decentralized manner without the agents having to negotiate about and commit to a joint policy at plan time. First we define the central planning notions and sketch the implementation of a planning system built on those notions. Afterwards we provide some case studies in order to evaluate the planner empirically and to show that the concept is useful for multi-agent systems in practice.Comment: In Proceedings M4M9 2017, arXiv:1703.0173

Experimental and simulation study on the effect of geometrical and flow parameters for combined-hole film cooling

Film cooling method was applied to the turbine blades to provide thermal protection from high turbine inlet temperatures in modern gas turbines. Recent literature discovers that combining two cylindrical holes of film cooling is one of the ways to further enhance the film cooling performances. In the present study, a batch of simulations and experiments involving two cylindrical holes with opposite compound angle were carried out and this two cylindrical hole also known as combined-hole film cooling. The main objective of this study is to determine the influence of different blowing ratio, M with a combination of different lateral distance between cooling holes (PoD), a streamwise distance between cooling holes (LoD) and compound angle of cooling hole (1/2) on the film cooling performance. The simulation of the present study had been carried out by using Computational Fluid Dynamic (CFD) with application of Shear Stress Transport (SST) turbulence model analysis from ANSYS CFX. Meanwhile, the experimental approach makes used of open end wind tunnel and the temperature distributions were measured by using infrared thermography camera. The purpose of the experimental approach in the present study is to validate three cases from all cases considered in the simulation approach. As the results shown, the lateral coverage was observed to be increased as PoD and 1/2 increased due to the interaction between two cooling air ejected from both cooling holes. Meanwhile, film cooling performance insignificantly changed when different LoD was applied. As the conclusion, a combination of the different geometrical parameters with various flow parameters produced a pattern of results. Therefore, the best configuration has been determined based on the average area of film cooling effectiveness. For M = 0.5, PoD = 1.0, LoD = 2.5 and 1 / 2 = -45o /+45o case is the most effective configuration. In the case of M = 1.0 and M = 1.5, PoD = 0.0, LoD = 3.5, 1 / 2 = -45o /+45o and PoD = 0.0, LoD = 2.5, 1 / 2 = -45o /+30o are the best configurations based on the overall performance of film cooling

Optimising Simulation Data Structures for the Xeon Phi

In this paper, we propose a lock-free architecture to accelerate logic gate circuit simulation using SIMD multi-core machines. We evaluate its performance on different test circuits simulated on the Intel Xeon Phi and 2 other machines. Comparisons are presented of this software/hardware combination with reported performances of GPU and other multi-core simulation platforms. Comparisons are also given between the lock free architecture and a leading commercial simulator running on the same Intel hardware

Comprehensive Monitor-Oriented Compensation Programming

Compensation programming is typically used in the programming of web service compositions whose correct implementation is crucial due to their handling of security-critical activities such as financial transactions. While traditional exception handling depends on the state of the system at the moment of failure, compensation programming is significantly more challenging and dynamic because it is dependent on the runtime execution flow - with the history of behaviour of the system at the moment of failure affecting how to apply compensation. To address this dynamic element, we propose the use of runtime monitors to facilitate compensation programming, with monitors enabling the modeller to be able to implicitly reason in terms of the runtime control flow, thus separating the concerns of system building and compensation modelling. Our approach is instantiated into an architecture and shown to be applicable to a case study.Comment: In Proceedings FESCA 2014, arXiv:1404.043

Collaborative Reuse of Streaming Dataflows in IoT Applications

Distributed Stream Processing Systems (DSPS) like Apache Storm and Spark Streaming enable composition of continuous dataflows that execute persistently over data streams. They are used by Internet of Things (IoT) applications to analyze sensor data from Smart City cyber-infrastructure, and make active utility management decisions. As the ecosystem of such IoT applications that leverage shared urban sensor streams continue to grow, applications will perform duplicate pre-processing and analytics tasks. This offers the opportunity to collaboratively reuse the outputs of overlapping dataflows, thereby improving the resource efficiency. In this paper, we propose \emph{dataflow reuse algorithms} that given a submitted dataflow, identifies the intersection of reusable tasks and streams from a collection of running dataflows to form a \emph{merged dataflow}. Similar algorithms to unmerge dataflows when they are removed are also proposed. We implement these algorithms for the popular Apache Storm DSPS, and validate their performance and resource savings for 35 synthetic dataflows based on public OPMW workflows with diverse arrival and departure distributions, and on 21 real IoT dataflows from RIoTBench.Comment: To appear in IEEE eScience Conference 201

Towards an Efficient Context-Aware System: Problems and Suggestions to Reduce Energy Consumption in Mobile Devices

Looking for optimizing the battery consumption is an open issue, and we think it is feasible if we analyze the battery consumption behavior of a typical context-aware application to reduce context-aware operations at runtime. This analysis is based on different context sensors configurations. Actually existing context-aware approaches are mainly based on collecting and sending context data to external components, without taking into account how expensive are these operations in terms of energy consumption. As a first result of our work in progress, we are proposing a way for reducing the context data publishing. We have designed a testing battery consumption architecture supported by Nokia Energy Profiler tool to verify consumption in different scenarios