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Asia and South Pacific Design Automation Conference

作者： Hui Li Sébastien Le Beux Gabriela Nicolescu Ian O'Connor Lyon Institute of Nanotechnology INL-UMR5270 Ecole Centrale de Lyon Ecully France Computer and Software Engineering Dept. Ecole Polytechnique de Montreal Montréal (QC) Canada

ISBN: (纸本)9781479977932

The many cores design research community have shown high interest in optical crossbars on chip for more than a decade. Key properties of optical crossbars, namely a) contention-free data routing b) low-latency communication and c) potential for high bandwidth through the use of WDM, motivate several implementations. These implementations demonstrate very different scalability and power efficiency ability depending on three key design factors: a) the network topology, b) the considered layout and c) the insertion losses induced by the fabrication process. The emerging design technique relying on multi-layer deposited silicon allows reducing optical losses, which may lead to significant reduction of the power consumption. In this paper, multi-layer deposited silicon based crossbars are proposed and compared. The results indicate that the proposed ring-based network exhibits, on average, 22% and 51.4% improvement for worst-case and average losses respectively compared to the most power-efficient related crossbars.

关键词： Optical waveguides IP networks Optical losses Optical device fabrication Layout Propagation losses

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An extension for AADL to model mixed-criticality avionic systems deployed on IMA architectures with TTEthernet 1

An extension for AADL to model mixed-criticality avionic sys...

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1st International Workshop on Architecture Centric Virtual Integration, ACVI 2014, Co-located with the 17th International Conference on Model Driven engineering Languages and Systems, MoDELS 2014

作者： Robati, Tiyam El Kouhen, Amine Gherbi, Abdelouahed Hamadou, Sardaouna Mullins, John Dept. of Software and IT Engineering École de Technologie Suprieure Canada Dept. of Computer and Software Eng Ecole Polytechnique de Montreal Canada

Integrated modular avionics architectures combined with the emerging SAE TTEthernet standard provides a strong infrastructure for the deployment of mixed-critical avionic applications having stringent safety, reliability and performance requirements. The integration of such systems is a very complex and challenging engineering task. Therefore, a model-based approach, which endows system engineers with a methodology and the supporting tools to cope with this complexity, is of a paramount importance. In this research paper, we present an extension for the standard architecture and analysis modeling language AADL to enable modeling integrated multi-critical avionic applications deployed on TTEthernet-based IMA architectures. In particular, we present a metamodel which extends the core AADL metamodel with concepts and constraints relevant for this domain, we define the concrete textual syntax for this extension and we outline the implementation of this extension using the Open Source AADL Tool Environment (OSATE). Finally, we illustrate our AADL extension using a case study based on the Flight Management System.

关键词： Modeling languages

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Numerical simulation of cavitating flow around a hydrofoil 4

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ASME 2014 4th Joint US-European Fluids engineering Division Summer Meeting, FEDSM 2014, Collocated with the ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels

作者： Tran, Tan Dung Nennemann, Bernd Vu, Thi Cong Guibault, François Department of Mechanical Engineering École Polytechnique de Montréal MontrealQC Canada Andritz-Hydro Ltd. MontrealQC Canada Department of Computer and Software Engineering École Polytechnique de Montréal MontrealQC Canada

ISBN: (纸本)9780791846261

The objective of this paper is to evaluate the applicability of different cavitation models and determine appropriate numerical parameters for cavitating flows around a hydrofoil. The simulations are performed for a NACA 66 foil at 6 degrees angle of attack, Reynolds number of 750 000 and for a cavitation number of 1.49 corresponding to the partial sheet cavitating regime. The incompressible, multiphase Reynoldsaveraged Navier-Stokes (RANS) equations are solved by the CFD solver CFX with Kubota and Merkle cavitation models. As part of the work, the Merkle model is implemented into CFX by User Fortran code because this model has shown good cavitation prediction capability according to the literature. The effects of the k-Ε and SST turbulence models on the cavitating flow dynamics are compared. Also, an investigation on structured and hybrid meshes with different mesh sizes and concentrations is carried out in order to better understand the mesh influence for this cavitation simulation. The local compressibility effect is considered by correcting the turbulent eddy viscosity inside the mixture vapor/liquid zones. The numerical results are validated by experiments conducted in a cavitation tunnel at the French Naval Academy. Copyright © 2014 by ASME.

关键词： Hydrofoils

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Investigation of cavitation models for steady and unsteady cavitating flow simulation

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International Journal of Fluid Machinery and Systems 2015年第4期8卷 240-253页

作者： Tran, Tan Dung Nennemann, Bernd Vu, Thi Cong Guibault, François Department of Mechanical Engineering École Polytechnique de Montréal 2900 Boulevard Edouard-Montpetit MontrealH3T 1J4 Canada Department of Computer and Software Engineering École Polytechnique de Montréal 2900 Boulevard Edouard-Montpetit MontrealH3T 1J4 Canada Andritz Hydro Canada Inc 6100 Trans Canada Hwy Pointe ClaireQCH9R 1B9 Canada

The objective of this paper is to evaluate the applicability of mass transfer cavitation models and determine appropriate numerical parameters for cavitating flow simulations. CFD simulations were performed for a NACA66 hydrofoil at cavitation numbers of 1.49 and 1.00, corresponding to steady sheet and unsteady sheet/cloud cavitating regimes using the Kubota and Merkle cavitation models. The Merkle model was implemented into CFX by User Fortran code. The Merkle cavitation model is found to give some improvements for cavitating flow simulation results for these cases. Turbulence modeling is also found to have an important contribution to the prediction quality of the simulations. The relationship between the turbulence viscosity modification, in order to take into account the local compressibility at the vapor/liquid interfaces, and the predicted numerical results is clarified. The limitations of current cavitating flow simulation techniques are discussed throughout the paper. © 2015 by the authors;licensee MDPI, Basel, Switzerland.

关键词： Cavitation

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Applying Formal Methods into Safety-Critical Health Applications

Lecture Notes in Computer Science (including subseries Lectu...

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Lecture Notes in computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 2014年 8822卷 195-208页

作者： Gholami, Mohammad-Reza Boucheneb, Hanifa VeriForm Lab Department of Computer and Software Engineering Ecole Polytechnique of Montreal Canada

software performs a critical role in almost every aspect of our daily life specially in the embedded systems of medical equipments. A key goal of software engineering is to make it possible for developers to construct systems that operate reliably regardless of their complexity. In this paper, by employing Model-Based Design for large and safety-related applications and applying formal verification techniques, we define specific properties to ensure that a software system satisfies its correctness criteria. We use the formal approach to study and verify the properties of a medical device known as Endotracheal intubation. We present how the system is modeled in the Simulink and Stateflow and present a functionality formalization. In order to formally prove some critical properties, we employ Simulink Design Verifier toolset. © 2014 Springer International Publishing Switzerland.

关键词： Biomedical equipment

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Multiscale navigation in large trace data

Multiscale navigation in large trace data

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Canadian Conference on Electrical and computer engineering (CCECE)

作者： Naser Ezzati-Jivan Michel R. Dagenais Department of Computer and Software Engineering Ecole Polytechnique de Montreal

One solution to handle large data sets is to organize and visualize them in a hierarchical model. This paper investigates hierarchical management of large trace logs and proposes an interactive zoomable timeline view to visualize the multiple levels of information generated by analyzing the execution trace logs. The view supports both the semantic (data) zooming and physical (visual) zooming. It displays a coarser layer first and provides some operations to explore and navigate the different layers of data. The method mainly facilitates the comprehension of the execution trace logs and can also be used to improve root cause analysis. The paper also discusses the hierarchical data model designed for organizing and visualizing the information at multiple levels.

关键词： Data visualization Abstracts Kernel Data models Data structures Navigation Aggregates

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Optical crossbars on chip, a comparative study based on worst-case losses

Optical crossbars on chip, a comparative study based on wors...

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作者： Le Beux, Sébastien Li, Hui Nicolescu, Gabriela Trajkovic, Jelena O'Connor, Ian Lyon Institute of Nanotechnology INL-UMR5270 Ecole Centrale de Lyon EcullyF-69134 France Computer and Software Engineering Dept. Ecole Polytechnique de Montréal MontrealQC Canada Electrical and Computer Engineering Department Concordia University MontrealQC Canada

The many-core design research community has shown high interest in optical crossbar on chip for more than a decade. Key properties of optical crossbars, namely (1) contention-free data routing, (2) low latency communication, and (3) potential for high bandwidth through the use of wavelength division multiplexing, motivate several implementations of this type of interconnect. These implementations demonstrate very different scalability and power efficiency abilities depending on three key design factors: (1) network topology, (2) considered layout, and (3) insertion losses induced by the fabrication process. In this paper, the worst-case optical losses of crossbar implementations are compared according to the factors mentioned earlier. The comparison results have the potential to help many-core system designer to select the most appropriate crossbar implementation according to, for instance, the number of IP cores and the die size. Copyright © 2014 John Wiley & Sons, Ltd.

关键词： Network-on-chip

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A model for carbon footprint optimization in an InterCloud environment

A model for carbon footprint optimization in an InterCloud e...

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IEEE International Conference on Cloud Networking (CLOUDNET)

作者： Valerie Danielle Justafort Ronald Beaubrun Samuel Pierre Computing and Software Engineering Department Ecole Polytechnique de Montreal Montreal Canada Department of Computer Science and Software Engineering Laval University Quebec Canada

In this paper, we address the problem of virtual machine (VM) placement in an InterCloud with regard to the reduction of carbon footprint in such computing environment. In order to minimize the data center Greenhouse Gas (GhG) emissions, this paper proposes a new mathematical formulation, where the placement approach is stated as a mixed integer programming problem which aims at minimizing the overall carbon footprint of the InterCloud. The proposed formulation presents an accurate carbon footprint evaluation based on joint optimization techniques, such as workload consolidation and cooling efficiency maximization, while considering the greenness of the data centers and the dynamic behavior of the IT equipment cooling fans. Simulation results showed that our model leads to optimal configurations with minimal carbon footprint in the InterCloud environment.

关键词： Servers Carbon Power demand Cooling Mathematical model Temperature distribution Cloud computing

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LTTng CLUST: A System-Wide Unified CPU and GPU Tracing Tool for OpenCL Applications

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Advances in software engineering 2015年第1期2015卷

作者： David Couturier Michel R. Dagenais Department of Computer and Software Engineering Polytechnique Montreal P.O. Box 6079 Station Downtown Montreal QC Canada H3C 3A7polymtl.ca

As computation schemes evolve and many new tools become available to programmers to enhance the performance of their applications, many programmers started to look towards highly parallel platforms such as Graphical Processing Unit (GPU). Offloading computations that can take advantage of the architecture of the GPU is a technique that has proven fruitful in recent years. This technology enhances the speed and responsiveness of applications. Also, as a side effect, it reduces the power requirements for those applications and therefore extends portable devices battery life and helps computing clusters to run more power efficiently. Many performance analysis tools such as LTTng , strace and SystemTap already allow Central Processing Unit (CPU) tracing and help programmers to use CPU resources more efficiently. On the GPU side, different tools such as Nvidia ’s Nsight , AMD ’s CodeXL , and third party TAU and VampirTrace allow tracing Application Programming Interface (API) calls and OpenCL kernel execution. These tools are useful but are completely separate, and none of them allow a unified CPU-GPU tracing experience. We propose an extension to the existing scalable and highly efficient LTTng tracing platform to allow unified tracing of GPU along with CPU’s full tracing capabilities.

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Linux Low-Latency Tracing for Multicore Hard Real-Time Systems

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Advances in computer engineering 2015年第1期2015卷

作者： Raphaël Beamonte Michel R. Dagenais Computer and Software Engineering Department Polytechnique Montreal C.P. 6079 Station Downtown Montréal QC Canada H3C 3A7polymtl.ca

Real-time systems have always been difficult to monitor and debug because of the timing constraints which rule out any tool significantly impacting the system latency and performance. Tracing is often the most reliable tool available for studying real-time systems. The real-time behavior of Linux systems has improved recently and it is possible to have latencies in the low microsecond range. Therefore, tracers must ensure that their overhead is within that range and predictable and scales well to multiple cores. The LTTng 2.0 tools have been optimized for multicore performance, scalability, and flexibility. We used and extended the real-time verification tool rteval to study the impact of LTTng on the maximum latency on hard real-time applications. We introduced a new real-time analysis tool to establish the baseline of real-time system performance and then to measure the impact added by tracing the kernel and userspace (UST) with LTTng . We then identified latency problems and accordingly modified LTTng-UST and the procedure to isolate the shielded real-time cores from the RCU interprocess synchronization routines. This work resulted in extended tools to measure the real-time properties of multicore Linux systems, a characterization of the impact of LTTng kernel and UST tracing tools, and improvements to LTTng .

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