2HOT: An Improved Parallel Hashed Oct-Tree N-Body Algorithm for Cosmological Simulation

We report on improvements made over the past two decades to our adaptive treecode N-body method (HOT). A mathematical and computational approach to the cosmological N-body problem is described, with performance and scalability measured up to 256k ($2^{18}$) processors. We present error analysis and scientific application results from a series of more than ten 69 billion ($4096^3$) particle cosmological simulations, accounting for $4 \times 10^{20}$ floating point operations. These results include the first simulations using the new constraints on the standard model of cosmology from the Planck satellite. Our simulations set a new standard for accuracy and scientific throughput, while meeting or exceeding the computational efficiency of the latest generation of hybrid TreePM N-body methods.Comment: 12 pages, 8 figures, 77 references; To appear in Proceedings of SC '1

マルチパーティー計算の効率的な構成と実装

電気通信大学201

HI Lightcones for LADUMA using Gadget-3 : performance profiling and application of an HPC code

Includes bibliographical references.This project concerns the investigation, performance profiling and optimisation of the high performance cosmological code, GADGET-3. This code was used to develop a synthetic field-of-view, or lightcone, for the MeerKAT telescope to replicate what it will observe when it conducts the LADUMA ultra-deep HI survey. This lightcone will assist in the planning process of the survey. The deliverables for this project are summarised as follows: * Provide an up-to-date performance evaluation and optimisation report for the cosmological simulation code GADGET-3. * Use GADGET-3 to produce an sufficiently high resolution simulation of a region of the Universe. • Develop a Python code to produce a lightcone which represents the MeerKAT telescope's field-of-view, by post-processing simulation output snapshots. * Extract relevant metadata from the simulation snapshots to provide additional insight into the simulated observation. * Produce an efficiently written and well documented software package to enable other researchers to produce synthetic lightcones

Languages and Tools for Optimization of Large-Scale Systems

Modeling and simulation are established techniques for solving design problems in a wide range of engineering disciplines today. Dedicated computer languages, such as Modelica, and efficient software tools are available. In this thesis, an extension of Modelica, Optimica, targeted at dynamic optimization of Modelica models is proposed. In order to demonstrate the Optimica extension, supporting software has been developed. This includes a modularly extensible Modelica compiler, the JModelica compiler, and an extension that supports also Optimica. A Modelica library for paper machine dryer section modeling, DryLib, has been developed. The classes in the library enable structured and hierarchical modeling of dryer sections at the application user level, while offering extensibility for the expert user. Based on DryLib, a parameter optimization problem, a model reduction problem, and an optimization-based control problem have been formulated and solved. A start-up optimization problem for a plate reactor has been formulated in Optimica, and solved by means of the Optimica compiler. In addition, the robustness properties of the start-up trajectories have been evaluated by means of Monte-Carlo simulation. In many control systems, it is necessary to consider interaction with a user. In this thesis, a manual control scheme for an unstable inverted pendulum system, where the inputs are bounded, is presented. The proposed controller is based on the notion of reachability sets and guarantees semi global stability for all references. An inverted pendulum on a two wheels robot has been developed. A distributed control system, including sensor processing algorithms and a stabilizing control scheme has been implemented on three on-board embedded processors