File-System Workload on a Scientific Multiprocessor

Many scientific applications have intense computational and I/O requirements. Although multiprocessors have permitted astounding increases in computational performance, the formidable I/O needs of these applications cannot be met by current multiprocessors a their I/O subsystems. To prevent I/O subsystems from forever bottlenecking multiprocessors and limiting the range of feasible applications, new I/O subsystems must be designed. The successful design of computer systems (both hardware and software) depends on a thorough understanding of their intended use. A system designer optimizes the policies and mechanisms for the cases expected to most common in the user's workload. In the case of multiprocessor file systems, however, designers have been forced to build file systems based only on speculation about how they would be used, extrapolating from file-system characterizations of general-purpose workloads on uniprocessor and distributed systems or scientific workloads on vector supercomputers (see sidebar on related work). To help these system designers, in June 1993 we began the Charisma Project, so named because the project sought to characterize 1/0 in scientific multiprocessor applications from a variety of production parallel computing platforms and sites. The Charisma project is unique in recording individual read and write requests-in live, multiprogramming, parallel workloads (rather than from selected or nonparallel applications). In this article, we present the first results from the project: a characterization of the file-system workload an iPSC/860 multiprocessor running production, parallel scientific applications at NASA's Ames Research Center

Low-Effort Specification Debugging and Analysis

Reactive synthesis deals with the automated construction of implementations of reactive systems from their specifications. To make the approach feasible in practice, systems engineers need effective and efficient means of debugging these specifications. In this paper, we provide techniques for report-based specification debugging, wherein salient properties of a specification are analyzed, and the result presented to the user in the form of a report. This provides a low-effort way to debug specifications, complementing high-effort techniques including the simulation of synthesized implementations. We demonstrate the usefulness of our report-based specification debugging toolkit by providing examples in the context of generalized reactivity(1) synthesis.Comment: In Proceedings SYNT 2014, arXiv:1407.493

Design of an integrated airframe/propulsion control system architecture

The design of an integrated airframe/propulsion control system architecture is described. The design is based on a prevalidation methodology that uses both reliability and performance. A detailed account is given for the testing associated with a subset of the architecture and concludes with general observations of applying the methodology to the architecture

Co-simulation techniques based on virtual platforms for SoC design and verification in power electronics applications

En las últimas décadas, la inversión en el ámbito energético ha aumentado considerablemente. Actualmente, existen numerosas empresas que están desarrollando equipos como convertidores de potencia o máquinas eléctricas con sistemas de control de última generación. La tendencia actual es usar System-on-chips y Field Programmable Gate Arrays para implementar todo el sistema de control. Estos dispositivos facilitan el uso de algoritmos de control más complejos y eficientes, mejorando la eficiencia de los equipos y habilitando la integración de los sistemas renovables en la red eléctrica. Sin embargo, la complejidad de los sistemas de control también ha aumentado considerablemente y con ello la dificultad de su verificación. Los sistemas Hardware-in-the-loop (HIL) se han presentado como una solución para la verificación no destructiva de los equipos energéticos, evitando accidentes y pruebas de alto coste en bancos de ensayo. Los sistemas HIL simulan en tiempo real el comportamiento de la planta de potencia y su interfaz para realizar las pruebas con la placa de control en un entorno seguro. Esta tesis se centra en mejorar el proceso de verificación de los sistemas de control en aplicaciones de electrónica potencia. La contribución general es proporcionar una alternativa a al uso de los HIL para la verificación del hardware/software de la tarjeta de control. La alternativa se basa en la técnica de Software-in-the-loop (SIL) y trata de superar o abordar las limitaciones encontradas hasta la fecha en el SIL. Para mejorar las cualidades de SIL se ha desarrollado una herramienta software denominada COSIL que permite co-simular la implementación e integración final del sistema de control, sea software (CPU), hardware (FPGA) o una mezcla de software y hardware, al mismo tiempo que su interacción con la planta de potencia. Dicha plataforma puede trabajar en múltiples niveles de abstracción e incluye soporte para realizar co-simulación mixtas en distintos lenguajes como C o VHDL. A lo largo de la tesis se hace hincapié en mejorar una de las limitaciones de SIL, su baja velocidad de simulación. Se proponen diferentes soluciones como el uso de emuladores software, distintos niveles de abstracción del software y hardware, o relojes locales en los módulos de la FPGA. En especial se aporta un mecanismo de sincronizaron externa para el emulador software QEMU habilitando su emulación multi-core. Esta aportación habilita el uso de QEMU en plataformas virtuales de co-simulacion como COSIL. Toda la plataforma COSIL, incluido el uso de QEMU, se ha analizado bajo diferentes tipos de aplicaciones y bajo un proyecto industrial real. Su uso ha sido crítico para desarrollar y verificar el software y hardware del sistema de control de un convertidor de 400 kVA

An Agent Based Model to Assess Crew Temporal Variability During U.S. Navy Shipboard Operations

Understanding the factors that affect human performance variability as well as their temporal impacts is an essential element in fully integrating and designing complex, adaptive environments. This understanding is particularly necessary for high stakes, time-critical routines such as those performed during nuclear reactor, air traffic control, and military operations. Over the last three decades significant efforts have emerged to demonstrate and apply a host of techniques to include Discrete Event Simulation, Bayesian Belief Networks, Neural Networks, and a multitude of existing software applications to provide relevant assessments of human task performance and temporal variability. The objective of this research was to design and develop a novel Agent Based Modeling and Simulation (ABMS) methodology to generate a timeline of work and assess impacts of crew temporal variability during U.S. Navy Small Boat Defense operations in littoral waters. The developed ABMS methodology included human performance models for six crew members (agents) as well as a threat craft, and incorporated varying levels of crew capability and task support. AnyLogic ABMS software was used to simultaneously provide detailed measures of individual sailor performance and of system-level emergent behavior. This methodology and these models were adapted and built to assure extensibility across a broad range of U.S. Navy shipboard operations. Application of the developed ABMS methodology effectively demonstrated a way to visualize and quantify impacts/uncertainties of human temporal variability on both workload and crew effectiveness during U.S. Navy shipboard operations

Enhancing Energy Production with Exascale HPC Methods

High Performance Computing (HPC) resources have become the key actor for achieving more ambitious challenges in many disciplines. In this step beyond, an explosion on the available parallelism and the use of special purpose processors are crucial. With such a goal, the HPC4E project applies new exascale HPC techniques to energy industry simulations, customizing them if necessary, and going beyond the state-of-the-art in the required HPC exascale simulations for different energy sources. In this paper, a general overview of these methods is presented as well as some specific preliminary results.The research leading to these results has received funding from the European Union's Horizon 2020 Programme (2014-2020) under the HPC4E Project (www.hpc4e.eu), grant agreement n° 689772, the Spanish Ministry of Economy and Competitiveness under the CODEC2 project (TIN2015-63562-R), and from the Brazilian Ministry of Science, Technology and Innovation through Rede Nacional de Pesquisa (RNP). Computer time on Endeavour cluster is provided by the Intel Corporation, which enabled us to obtain the presented experimental results in uncertainty quantification in seismic imagingPostprint (author's final draft

Army-NASA aircrew/aircraft integration program (A3I) software detailed design document, phase 3

The capabilities and design approach of the MIDAS (Man-machine Integration Design and Analysis System) computer-aided engineering (CAE) workstation under development by the Army-NASA Aircrew/Aircraft Integration Program is detailed. This workstation uses graphic, symbolic, and numeric prototyping tools and human performance models as part of an integrated design/analysis environment for crewstation human engineering. Developed incrementally, the requirements and design for Phase 3 (Dec. 1987 to Jun. 1989) are described. Software tools/models developed or significantly modified during this phase included: an interactive 3-D graphic cockpit design editor; multiple-perspective graphic views to observe simulation scenarios; symbolic methods to model the mission decomposition, equipment functions, pilot tasking and loading, as well as control the simulation; a 3-D dynamic anthropometric model; an intermachine communications package; and a training assessment component. These components were successfully used during Phase 3 to demonstrate the complex interactions and human engineering findings involved with a proposed cockpit communications design change in a simulated AH-64A Apache helicopter/mission that maps to empirical data from a similar study and AH-1 Cobra flight test