Recently, an adaptive unified differential evolution algorithm for single-objective global optimization was proposed in an internal report. Instead of the multiple mutation strategies in conventional differential evolution algorithms, this algorithm employs a single equation unifying multiple strategies into one expression. It has the virtue of mathematical simplicity and also provides users the flexibility for broader exploration of the space of mutation operators. However, the four control parameters used in the unified mutation expression might slow down the speed of convergence due to an over exploration of the search space. In this paper, we systematically studied the choice of those control parameters in the unified mutation strategy using fourteen unimodal and multimodal functions from the CEC2005 benchmark. Those numerical results suggest that the use of three control parameters in the unified mutation strategy improves the performance of the original algorithm and shows promising performance in comparison to several conventional differential evolution algorithms.

Modern scientific datasets present numerous data management and analysis challenges. State-of-the-art index and query technologies are critical for facilitating interactive exploration of large datasets, but numerous challenges remain in terms of designing a system for processing general scientific datasets. The system needs to be able to run on distributed multi-core platforms, efficiently utilize underlying I/O infrastructure, and scale to massive datasets.

The high energy colliders are essential to study the inner structure of nuclear and elementary particles. A parallel particle simulation code, BeamBeam3D, has been developed and actively used to model the beam dynamics and to optimize the performance of these colliders. In this paper, we analyzed the performance characteristics of BeamBeam3D on four leading high performance computing architectures, including a massive parallel system, a commodity-based cluster, an advanced vector platform, and a novel architecture focused on low power consumption and high density. We examine how to partition the workload among the processors to effectively use the computing resources, whether these platforms exhibit similar performance bottlenecks and how to address them, whether some platforms perform substantially better than others, and finally, the implications of BeamBeam3D for the design of the next generation supercomputer architectures

An accurate modeling of the beam-beam interaction is essential to maximizing the luminosity in existing and future colliders. BeamBeam3D was the first parallel code that can be used to study this interaction fully self-consistently on high-performance computing platforms. Various all-to-all personalized communication (AAPC) algorithms dominate its communication patterns, for which we developed a sequence of performance models using a series of micro-benchmarks. We find that for SMP based systems the most important performance constraint is node-adapter contention, while for 3D-Torus topologies good performance models are not possible without considering link contention. The best average model prediction error is very low on SMP based systems with of 3% to 7%. On torus based systems errors of 29% are higher but optimized performance can again be predicted within 8% in some cases. These excellent results across five different systems indicate that this methodology for performance modeling can be applied to a large class of algorithms.1

In this paper we present a self-consistent simulation model of colliding beams in high energy accelerators. The model, which is based on a particle-in-cell method, uses a new developed shifted-Green function algorithm for the efficient calculation of the beam-beam interaction. The model uses transfer maps to treat the external focusing elements and a stochastic map to treat radiation damping and quantum excitation of the beams. In the parallel implementation we studied various strategies to deal with the particular nature of the colliding beam system - a system in which there can be significant particle movement between beam-beam collisions. We chose a particle-field decomposition approach instead of the conventional domain decomposition or particle decomposition approach. The particle-field approach leads to good load balance, reduced communication cost, and shows the best scalability on an IBM SP3 among the three parallel implementations we studied. A performance test of the beam-beam model on a Cray T3E, IBM SP3, and a PC cluster is presented. As an application, we studied the effect of long-range collisions on antiproton lifetime in the Fermilab Tevatron.

This paper presents two new hardware-assisted rendering techniques developed for interactive visualization of the terascale data generated from numerical modeling of next-generation accelerator designs. The first technique, based on a hybrid rendering approach, makes possible interactive exploration of large-scale particle data from particle beam dynamics modeling. The second technique, based on a compact texture-enhanced representation, exploits the advanced features of commodity graphics cards to achieve perceptually effective visualization of the very dense and complex electromagnetic fields produced from the modeling of reflection and transmission properties of open structures in an accelerator design. Because of the collaborative nature of the overall accelerator modeling project, the visualization technology developed is for both desktop and remote visualization settings. We have tested the techniques using both time-varying particle data sets containing up to one billion particles per time step and electromagnetic field data sets with millions of mesh elements.

In many plasma physics and changed-particle beam dynamics problems, Coulomb collisions are modeled by a Fokker-Planck equation. In order to incorporate these collisions, we present a three-dimensional parallel Langevin simulation method using a Particle-In-Cell (PIC) approach implemented on high-performance parallel computers. We perform, for the first time, a fully self-consistent simulation, in which the friction and diffusion coefficients are computed from first principles. We employ a two-dimensional domain decomposition approach within a message passing programming paradigm along with dynamic load balancing. Object oriented programming is used to encapsulate details of the communication syntax as well as to enhance reusability and extensibility. Performance tests on the SGI Origin 2000, IBM SP RS/6000 and the Cray T3E-900 have demonstrated good scalability. As a test example, we demonstrate the collisional relaxation to a final thermal equilibrium of a beam with an initially anisotropic velocity distribution.

Article An object-oriented parallel particle-in-cell code for beam dynamics simulation in linear accelerators Share on Authors: J. Qiang LANL, Los Alamos, NM LANL, Los Alamos, NMView Profile , R. D. Ryne LANL, Los Alamos, NM LANL, Los Alamos, NMView Profile , S. Habib LANL, Los Alamos, NM LANL, Los Alamos, NMView Profile , V. Decyk UCLA, Los Angeles, CA UCLA, Los Angeles, CAView Profile Authors Info & Claims SC '99: Proceedings of the 1999 ACM/IEEE conference on SupercomputingJanuary 1999 Pages 55–eshttps://doi.org/10.1145/331532.331587Online:01 January 1999Publication History 4citation551DownloadsMetricsTotal Citations4Total Downloads551Last 12 Months3Last 6 weeks0 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteGet Access