Optimization of lattice Boltzmann simulations on heterogeneous computers

High-performance computing systems are more and more often based on accelerators. Computing applications targeting those systems often follow a host-driven approach, in which hosts offload almost all compute-intensive sections of the code onto accelerators; this approach only marginally exploits the computational resources available on the host CPUs, limiting overall performances. The obvious step forward is to run compute-intensive kernels in a concurrent and balanced way on both hosts and accelerators. In this paper, we consider exactly this problem for a class of applications based on lattice Boltzmann methods, widely used in computational fluid dynamics. Our goal is to develop just one program, portable and able to run efficiently on several different combinations of hosts and accelerators. To reach this goal, we define common data layouts enabling the code to exploit the different parallel and vector options of the various accelerators efficiently, and matching the possibly different requirements of the compute-bound and memory-bound kernels of the application. We also define models and metrics that predict the best partitioning of workloads among host and accelerator, and the optimally achievable overall performance level. We test the performance of our codes and their scaling properties using, as testbeds, HPC clusters incorporating different accelerators: Intel Xeon Phi many-core processors, NVIDIA GPUs, and AMD GPUs

Forecasting Recharging Demand to Integrate Electric Vehicle Fleets in Smart Grids

Electric vehicle fleets and smart grids are two growing technologies. These technologies provided new possibilities to reduce pollution and increase energy efficiency. In this sense, electric vehicles are used as mobile loads in the power grid. A distributed charging prioritization methodology is proposed in this paper. The solution is based on the concept of virtual power plants and the usage of evolutionary computation algorithms. Additionally, the comparison of several evolutionary algorithms, genetic algorithm, genetic algorithm with evolution control, particle swarm optimization, and hybrid solution are shown in order to evaluate the proposed architecture. The proposed solution is presented to prevent the overload of the power grid

Toward an integrated conceptualization of the service and service system concepts: a systems approach

Service and service systems concepts are fundamental constructs for the development of the emergent SSME, ITSM, and Service Oriented Software (SOS) knowledge streams. A diversified literature has provided a richness of findings, but at the same time, the lack of standardized conceptualizations is a source of confusion to IT practitioners and academics. Given this problematic situation, we pose that a systems approach is useful to address it. In this article, we review and synthesize key studies in these knowledge streams to design: (i) a framework to characterize both concepts under a system view and, (ii) harmonized definitions (e.g. identification of shared and essential properties) for such fundamental concepts. Our main contribution is scholastic, but we are confident that the posed conceptual artifacts can be further used to elaborate standardized definition for the IT service and IT service system constructs, as well as analysis tools for describe real service systems

Toward an integrated conceptualization of the service and service system concepts: A systems approach

Service and service systems concepts are fundamental constructs for the development of the emergent SSME, ITSM, and Service Oriented Software (SOS) knowledge streams. A diversified literature has provided a richness of findings, but at the same time, the lack of standardized conceptualizations is a source of confusion to IT practitioners and academics. Given this problematic situation, we pose that a systems approach is useful to address it. In this article, we review and synthesize key studies in these knowledge streams to design: (i) a framework to characterize both concepts under a system view and, (ii) harmonized definitions (e.g. identification of shared and essential properties) for such fundamental concepts. Our main contribution is scholastic, but we are confident that the posed conceptual artifacts can be further used to elaborate standardized definition for the IT service and IT service system constructs, as well as analysis tools for describe real service systems

Open MAS Architecture. Providing Real Time Solutions

This presents a study in which a high level abstract architecture was used to design open multi-agent systems and virtual organizations that offer services with temporal constraints implemented by Real-Time Agents. The results will demonstrate how the proposed architecture, with features that make it suitable for development of open MAS (Multi-Agent Systems), allows us to add specific functionality and real time services

Model-Driven Service Level Management

Abstract. Service-level agreements (SLA) definition and monitoring are open issues within the IT Service Management (ITSM) domain. Our main goals are to propose a model-based approach to IT services SLA specification and compliance verification. The specification part will be accomplished by proposing a SLA language -a domain specific language (DSL) for defining quality attributes as non functional requirements (NFRs) in the context of ITSM. Its metamodel will be an extension of the meta-model of an adopted process modeling language for IT services. As such, it will be possible to ground SLA definition on the corresponding IT service model constructs. This will allow that SLA monitoring and compliance validation could occur at a level of abstraction that is understood by all the stakeholders involved in the service specification

Overview of the 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES)

Substantial uncertainties still exist in the scientific understanding of the possible interactions between urban and natural (biogenic) emissions in the production and transformation of atmospheric aerosol and the resulting impact on climate change. The US Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program's Carbonaceous Aerosol and Radiative Effects Study (CARES) carried out in June 2010 in Central Valley, California, was a comprehensive effort designed to improve this understanding. The primary objective of the field study was to investigate the evolution of secondary organic and black carbon aerosols and their climate-related properties in the Sacramento urban plume as it was routinely transported into the forested Sierra Nevada foothills area. Urban aerosols and trace gases experienced significant physical and chemical transformations as they mixed with the reactive biogenic hydrocarbons emitted from the forest. Two heavily-instrumented ground sites – one within the Sacramento urban area and another about 40 km to the northeast in the foothills area – were set up to characterize the evolution of meteorological variables, trace gases, aerosol precursors, aerosol size, composition, and climate-related properties in freshly polluted and "aged" urban air. On selected days, the DOE G-1 aircraft was deployed to make similar measurements upwind and across the evolving Sacramento plume in the morning and again in the afternoon. The NASA B-200 aircraft, carrying remote sensing instruments, was also deployed to characterize the vertical and horizontal distribution of aerosols and aerosol optical properties within and around the plume. This overview provides: (a) the scientific background and motivation for the study, (b) the operational and logistical information pertinent to the execution of the study, (c) an overview of key observations and initial findings from the aircraft and ground-based sampling platforms, and (d) a roadmap of planned data analyses and focused modeling efforts that will facilitate the integration of new knowledge into improved representations of key aerosol processes and properties in climate models.United States. Dept. of Energy. Atmospheric System Research Program (Contract DE-AC06-76RLO 1830)United States. National Oceanic and Atmospheric AdministrationUnited States. National Aeronautics and Space Administration. HQ Science Mission Directorate Radiation Sciences ProgramUnited States. National Aeronautics and Space Administration. CALIPSO ProgramUnited States. Dept. of Energy. Atmospheric Radiation Measurement Program (Interagency Agreement No. DE-AI02-05ER63985

Semiconductor Optical Amplifiers and mm-Wave Wireless Links for Converged Access Networks

Future access networks are converged optical-wireless networks, where fixed-line and wireless services share the same infrastructure. In this book, semiconductor optical amplifiers (SOA) and mm-wave wireless links are investigated, and their use in converged access networks is explored: SOAs compensate losses in the network, and thereby extend the network reach. Millimeter-wave wireless links substitute fiber links when cabling is not economical

NASA Lewis Research Center Futuring Workshop

On October 21 and 22, 1986, the Futures Group ran a two-day Futuring Workshop on the premises of NASA Lewis Research Center. The workshop had four main goals: to acquaint participants with the general history of technology forecasting; to familiarize participants with the range of forecasting methodologies; to acquaint participants with the range of applicability, strengths, and limitations of each method; and to offer participants some hands-on experience by working through both judgmental and quantitative case studies. Among the topics addressed during this workshop were: information sources; judgmental techniques; quantitative techniques; merger of judgment with quantitative measurement; data collection methods; and dealing with uncertainty