Intelligent vehicles systems are becoming more complex and with that the development and testing complexity of such systems. As real world tests are not sufficient anymore, simulation driven testing and development becomes indispensably important. A key element of intelligent vehicles simulation is hereby the generation of dynamic traffic situations via scenario engines. Such frameworks need to be flexible enough to model highly diverse concrete and implicit scenarios. To meet these demanding needs, we developed the OpenSource YASE (Yet Agnostic/ Yet Another Scenario Engine) framework. It contains scenario file compiler frontends to load scenarios and a behavior tree implementation for scenario execution. In this paper we present the novel approach of YASE to combine concrete scenarios, implicit traffic, scenery behavior and test criteria evaluation into one holistic framework. This modular approach allows to compose any arbitrary behavior needed for intelligent vehicle development and testing. First, the general functionality of behavior trees is introduced. N ext, we demonstrate the implementation of a concrete Euro NCAP scenario. For this scenario we explain the execution tree traversals for exemplary traffic situations. This is followed by implementations of a driver and a traffic model as a behavior tree. We elaborate in this context the composability characteristics of the used approach by reusing nodes in different contexts and combining scenario nodes with models. Finally, we highlight the model capabilities with a large scaled simulation with more then 8 million covered kilometers of highway traffic within the time frame of 15 simulated years.

Abstract With ever-increasing computational power, larger computational domains are employed and thus the data output grows as well. Writing this data to disk can become a significant part of runtime if done serially. Even if the output is done in parallel, e.g., via MPI I/O, there are many user-space parameters for tuning the performance. This paper focuses on the available parameters for the Lustre file system and the Cray MPICH implementation of MPI I/O. Experiments on the Cray XC40 Hazel Hen using a Cray Sonexion 2000 Lustre file system were conducted. In the experiments, the core count, the block size and the striping configuration were varied. Based on these parameters, heuristics for striping configuration in terms of core count and block size were determined, yielding up to a 32-fold improvement in write rate compared to the default. This corresponds to 85 GB/s of the peak bandwidth of 202.5 GB/s. The heuristics are shown to be applicable to a small test program as well as a complex application.

Real-valued black-box optimization of badly behaved and not well understood functions is a wide topic in many scientific areas. Possible applications range from maximizing portfolio profits in financial mathematics over efficient training of neuronal networks in computational linguistics to parameter identification of metabolism models in industrial biotechnology. This paper presents a comparison of several global as well as local optimization strategies applied to the task of efficiently identifying free parameters of a metabolic network model. A focus is being set on the ease of adopting these strategies to modern, highly parallel architectures. Finally an outlook on the possible parallel performance is being presented.

Abstract The Abstract Data and Communication Library (ADCL) is an adaptive communication library optimizing application level group communication operations at runtime. The library provides for a given communication pattern a large number of implementations and incorporates a runtime selection logic in order to choose the implementation leading to the highest performance. In this paper, we demonstrate how an application utilizing ADCL is deployed on a wide range of HPC architectures, including an IBM Blue Gene/L, an NEC SX‐8, an IBM Power PC cluster using an IBM Federation Switch, an AMD Opteron cluster utilizing a 4xInfiniBand and a Gigabit Ethernet network, and an Intel EM64T cluster using a hierarchical Gigabit Ethernet network with reduced uplink bandwidth. We demonstrate, how different implementations for the three‐dimensional neighborhood communication lead to the minimal execution time of the application on different architectures. ADCL gives the user the advantage of having to maintain only a single version of the source code and still have the ability to achieve close to optimal performance for the application on all architectures. Copyright © 2010 John Wiley & Sons, Ltd.

When an adaptive software component is employed to select the best-performing implementation for a communication operation at runtime, the correctness of the decision taken strongly depends on detecting and removing outliers in the data used for the comparison. This automatic decision is greatly complicated by the fact that the types and quantities of outliers depend on the network interconnect and the nodes assigned to the job by the batch scheduler. This paper evaluates four different statistical methods used for handling outliers, namely a standard interquartile range method, a heuristic derived from the trimmed mean value, cluster analysis and a method using robust statistics. Using performance data from the Abstract Data and Communication Library (ADCL) we evaluate the correctness of the decisions made with each statistical approach over three fundamentally different network interconnects, namely a highly reliable InfiniBand network, a gigabit Ethernet network having a larger variance in the performance, and a hierarchical gigabit Ethernet network.

The development of the Grid has opened new possibilities for scientists and engineers to execute large-scale modeling experiments. This has stimulated the generation and development of tools for the creation and management of complex computing experiments in the Grid. Among these, tools for the automation of the programming of experiments play a significant role. In this paper we present GriCoL, which we propose as a simple and efficient language for the description of complex Grid experiments. We also describe the environment within which GriCoL works, namely the Science Experimental Grid Laboratory (SEGL) system for designing and executing complex experiments. As an illustration, the paper includes the description of a biochemical experiment using Molecular Dynamics simulations.

This paper introduces an MPI test suite to thoroughly test the correctness of an MPI-implementation. Scientific applications require stable tools and libraries for portable and efficient programming, e. g. when depending on the single-sided communication on multiple platforms. This test suite was originally used to check the correct transmission of data in the PACX-MPI implementation, but has been mainly used and extended to test the development of the new Open MPI implementation. The tool has been designed to be easily extendible in order to integrate new tests using the underlying functionality

High performance computing has gradually shifted from the realm of research into development and partially even into the production cycles of industry. High performance computers therefore have to be integrated into production environments that demand the simultaneous solution of multidisciplinary physics problems. Supercomputer centers can learn from these new challenges imposed by industry. The concepts of workflow and production cycle open up a new horizon for integrating systems and software into what is called a distributed 'Teraflop-workbench' approach. Terascale storage and communication infrastructures eventually needed to support such an environment.

Abstract Grid computing has become a popular concept in the last few years. While in the beginning the driving force was metacomputing, the focus has now shifted towards resource management issues and concepts like ubiquitous computing. For the High‐Performance Computing Center Stuttgart (HLRS) the key challenges of Grid computing have come from the demands of its users and customers. With high‐speed networks in place, programmers expect to be able to exploit the overall performance of several instruments and high‐speed systems for their applications. In order to meet these demands, HLRS has set out a research effort to provide these users with the necessary tools to develop and run their codes on clusters of supercomputers. This has resulted in the development of a basic Grid‐computing environment for technical and scientific computing. In this paper we describe the building blocks of this software development environment and focus specifically on communication and debugging. We present the Grid‐enabled MPI implementation PACX‐MPI and the MPI debugger MARMOT. Copyright © 2002 John Wiley & Sons, Ltd.

Coupling computer resources to work on a given problem has been a successful strategy for years. Due to the existence of high bandwidth WAN it has become possible to couple big machines to build clusters that outperform the most powerful existing single computers. The article discusses such a powerful cluster, a metacomputer. While for MPPs the message passing model was standardized already 4 years ago (1995), a standard for interoperable MPI has only been published recently. We briefly present an approach for MPI based metacomputing called PACX-MPI. We also describe other approaches, and give an overview of the technical concept.