399,732 research outputs found
RPPM : Rapid Performance Prediction of Multithreaded workloads on multicore processors
Analytical performance modeling is a useful complement to detailed cycle-level simulation to quickly explore the design space in an early design stage. Mechanistic analytical modeling is particularly interesting as it provides deep insight and does not require expensive offline profiling as empirical modeling. Previous work in mechanistic analytical modeling, unfortunately, is limited to single-threaded applications running on single-core processors.
This work proposes RPPM, a mechanistic analytical performance model for multi-threaded applications on multicore hardware. RPPM collects microarchitecture-independent characteristics of a multi-threaded workload to predict performance on a previously unseen multicore architecture. The profile needs to be collected only once to predict a range of processor architectures. We evaluate RPPM's accuracy against simulation and report a performance prediction error of 11.2% on average (23% max). We demonstrate RPPM's usefulness for conducting design space exploration experiments as well as for analyzing parallel application performance
High-speed simulation of PCB emission and immunity with frequency-domain IC/LSI source models
Some recent results from research conducted in the EMC group at Okayama University are reviewed. A scheme for power-bus modeling with an analytical method is introduced. A linear macro-model for ICs/LSIs, called the LECCS model, has been developed for EMI and EMS simulation. This model has a very simple structure and is sufficiently accurate. Combining the LECCS model with analytical simulation techniques for power-bus resonance simulation provides a method for high-speed EMI simulation and decoupling evaluation related to PCB and LSI design. A useful explanation of the common-mode excitation mechanism, which utilizes the imbalance factor of a transmission line, is also presented. Some of the results were investigated by implementing prototypes of a high-speed EMI simulator, HISES. </p
Power aware early design stage hardware software co-optimization
Co-optimizing hardware and software can lead to substantial performance and energy benefits, and is becoming an increasingly important design paradigm. In scientific computing, power constraints increasingly necessitate the return to specialized chips such as Intelâs MIC or IBMâs Blue-Gene architectures. To enable hardware/software co-design in early stages of the design cycle, we propose a simulation infrastructure methodology by combining high-abstraction performance simulation using Sniper with power modeling using McPAT and custom DRAM power models. Sniper/McPAT is fast â simulation speed is around 2 MIPS on an 8-core host machine â because it uses analytical modeling to abstract away core performance during multi-core simulation. We demonstrate Sniper/McPATâs accuracy through validation against real hardware; we report average performance and power prediction errors of 22.1% and 8.3%, respectively, for a set of SPEComp benchmarks
Modeling OpAmp-induced harmonic distortion for switched-capacitor ÎŁÎ modulator design
This communication reports a new modeling of opamp-induced harmonic distortion in SC ÎŁÎ modulators, which is aimed to optimum design of this kind of circuit for high-performance applications. We analyze incomplete transfer of charge in a SC integrator and use power expansion and nonlinear fitting to obtain analytical models to represent harmonic distortion as function of the opamp finite gain-bandwidth (GB), slew-rate (SR) and nonlinear DC gain. Calculated models apply for all modulator architectures where harmonic distortion is dominated by the first integrator in the chain. We show that results provided by the new analytical models fit well to that obtained by simulation in time domain and have accuracy levels much larger than that provided by previously reported modeling approaches
Business process modeling and simulation
The textbook provides the essentials of the Business Process (BP) Modeling and Simulation (M&S) from the verbal BP description to the formulation of the mathematical scheme of the model and the simulation program.
Both the analytical modeling and the simulation approaches to BP M&S are considered. Special attention is given to the theoretical and practical aspects of the BP M&S. The text covers the following topics: fundamentals of the BP M&S, conceptual modeling using IDEF3 standard, cost metrics and the activity based costing, analytical modeling (queuing networks, linear and dynamic programming), simulation with GPSS, timed Petri Nets, and Crystal Ball toolkits. Case studies include BP simulations with BPwin and GPSS.
The intended readers are senior graduate students and junior postgraduate students of computer science and industrial management
High-accuracy Geant4 simulation and semi-analytical modeling of nuclear resonance fluorescence
Nuclear resonance fluorescence (NRF) is a photonuclear interaction that
enables highly isotope-specific measurements in both pure and applied physics
scenarios. High-accuracy design and analysis of NRF measurements in complex
geometries is aided by Monte Carlo simulations of photon physics and transport,
motivating Jordan and Warren (2007) to develop the G4NRF codebase for NRF
simulation in Geant4. In this work, we enhance the physics accuracy of the
G4NRF code and perform improved benchmarking simulations. The NRF cross section
calculation in G4NRF, previously a Gaussian approximation, has been replaced
with a full numerical integration for improved accuracy in thick-target
scenarios. A high-accuracy semi-analytical model of expected NRF count rates in
a typical NRF measurement is then constructed and compared against G4NRF
simulations for both simple homogeneous and more complex heterogeneous
geometries. Agreement between rates predicted by the semi-analytical model and
G4NRF simulation is found at a level of in simple test cases and
in more realistic scenarios, improving upon the level
of the initial benchmarking study and establishing a highly-accurate NRF
framework for Geant4.Comment: 16 pages, 6 figures, revised for peer revie
Semi-Numerical Simulation of Reionization with Semi-Analytical Modeling of Galaxy Formation
In a semi-numerical model of reionization, the evolution of ionization
fraction is simulated approximately by the ionizing photon to baryon ratio
criterion. In this paper we incorporate a semi-analytical model of galaxy
formation based on the Millennium II N-body simulation into the semi-numerical
modeling of reionization. The semi-analytical model is used to predict the
production of ionizing photons, then we use the semi-numerical method to model
the reionization process. Such an approach allows more detailed modeling of the
reionization, and also connects observations of galaxies at low and high
redshifts to the reionization history. The galaxy formation model we use was
designed to match the low- observations, and it also fits the high redshift
luminosity function reasonably well, but its prediction on the star formation
falls below the observed value, and we find that it also underpredicts the
stellar ionizing photon production rate, hence the reionization can not be
completed at without taking into account some other potential
sources of ionization photons. We also considered simple modifications of the
model with more top heavy initial mass functions (IMF), with which the
reionization can occur at earlier epochs. The incorporation of the
semi-analytical model may also affect the topology of the HI regions during the
EoR, and the neutral regions produced by our simulations with the
semi-analytical model appeared less poriferous than the simple halo-based
models.Comment: 13 pages, 8 figures, RAA accepte
Space-time numerical simulation and validation of analytical predictions for nonlinear forced dynamics of suspended cables
This paper presents space-time numerical simulation and validation of analytical predictions for the finite-amplitude forced dynamics of suspended cables. The main goal is to complement analytical and numerical solutions, accomplishing overall quantitative/qualitative comparisons of nonlinear response characteristics. By relying on an approximate, kinematically non-condensed, planar modeling, a simply supported horizontal cable subject to a primary external resonance and a 1:1, or 1:1 vs. 2:1, internal resonance is analyzed. To obtain analytical solution, a second-order multiple scales approach is applied to a complete eigenfunction-based series of nonlinear ordinary-differential equations of cable damped forced motion. Accounting for both quadratic/cubic geometric nonlinearities and multiple modal contributions, local scenarios of cable uncoupled/coupled responses and associated stability are predicted, based on chosen reduced-order models. As a cross-checking tool, numerical simulation of the associated nonlinear partial-differential equations describing the dynamics of the actual infinite-dimensional system is carried out using a finite difference technique employing a hybrid explicit-implicit integration scheme. Based on system control parameters and initial conditions, cable amplitude, displacement and tension responses are numerically assessed, thoroughly validating the analytically predicted solutions as regards the actual existence, the meaningful role and the predominating internal resonance of coexisting/competing dynamics. Some methodological aspects are noticed, along with a discussion on the kinematically approximate versus exact, as well as planar versus non-planar, cable modeling
Analytical modeling and 3D finite element simulation of line edge roughness in scatterometry
The influence of edge roughness in angle resolved scatterometry at
periodically structured surfaces is investigated. A good description of the
radiation interaction with structured surfaces is crucial for the understanding
of optical imaging processes like, e.g. in photolithography. We compared an
analytical 2D model and a numerical 3D simulation with respect to the
characterization of 2D diffraction of a line grating involving structure
roughness. The results show a remarkably high agreement. The diffraction
intensities of a rough structure can therefore be estimated using the numerical
simulation result of an undisturbed structure and an analytically derived
correction function. This work allows to improve scatterometric results for the
case of practically relevant 2D structures
Pre-shuttle lidar system research
Included are the results of the initial phase of a simulation study in connection with photomultiplier tubes (PMT) and associated networks and an analytical study of atmospheric physics (including multiscattering) leading to modeling studies in connection with differential absorption lidar (DIAL) observations. This effort was in support of the ER-2 aircraft DIAL projects
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