Search results for "simulation methods"
showing 10 items of 20 documents
Structural Characterization of Organics Using Manual and Automated Electron Diffraction
2010
In the last decade the importance of transmission electron microscopic studies has become increasingly important with respect to the characterization of organic materials, ranging from small organic molecules to polymers and biological macromolecules. This review will focus on the use of transmission electron microscope to perform electron crystallography experiments, detailing the approaches in acquiring electron crystallographic data. The traditional selected area approach and the recently developed method of automated diffraction tomography (ADT) will be discussed with special attention paid to the handling of electron beam sensitive organic materials.
Comparing equilibration schemes of high-molecular-weight polymer melts with topological indicators.
2021
Abstract Recent theoretical studies have demonstrated that the behaviour of molecular knots is a sensitive indicator of polymer structure. Here, we use knots to verify the ability of two state-of-the-art algorithms—configuration assembly and hierarchical backmapping—to equilibrate high-molecular-weight (MW) polymer melts. Specifically, we consider melts with MWs equivalent to several tens of entanglement lengths and various chain flexibilities, generated with both strategies. We compare their unknotting probability, unknotting length, knot spectra, and knot length distributions. The excellent agreement between the two independent methods with respect to knotting properties provides an addit…
General Introduction to Computer Simulation Methods
1986
Computer simulation methods are now an established tool in many branches of science. The motivation for computer simulations of physical systems are manifold. One of the main motivations is that one eliminates approximations with computer simulations. Usually to treat a problem analytically (if it can be done at all) one needs to resort to some kind of approximation; for exam- ple a mean-field-type approximation. With a computer simulation we have the ability to study systems not yet tractable with analytical methods. The computer simulation approach allows one to study complex systems and gain insight into their behaviour. Indeed, the complexity can go far beyond the reach of present analy…
Second generation Car-Parrinello molecular dynamics
2014
Computer simulation methods, such as Monte Carlo or molecular dynamics, are very powerful theoretical techniques to provide detailed and essentially exact informations on rather complex classical many-body problems. With the advent of ab initio molecular dynamics (AIMD), where finite-temperature dynamical trajectories are generated using interatomic forces which are calculated on the fly using accurate electronic structure calculations, the scope of computational research has been greatly extended. This review is intended to outline the basic principles as well as being a survey of the field. Beginning with the derivation of Born–Oppenheimer molecular dynamics, the Car–Parrinello method and…
Fast simulation of muons produced at the SHiP experiment using Generative Adversarial Networks
2019
This paper presents a fast approach to simulating muons produced in interactions of the SPS proton beams with the target of the SHiP experiment. The SHiP experiment will be able to search for new long-lived particles produced in a 400~GeV$/c$ SPS proton beam dump and which travel distances between fifty metres and tens of kilometers. The SHiP detector needs to operate under ultra-low background conditions and requires large simulated samples of muon induced background processes. Through the use of Generative Adversarial Networks it is possible to emulate the simulation of the interaction of 400~GeV$/c$ proton beams with the SHiP target, an otherwise computationally intensive process. For th…
Electron crystallography and non-linear optics
1999
Electron crystallography can be used to obtain specific information about molecular parameters such as the polarisability, dipole moment, and hyperpolarisability. In this, work we show how a combination of quantum mechanics and simulation methods can be used to solve several unknown organic structures and how the calculated molecular parameters can be used to predict the corresponding physical properties of the crystals.
Comparison between simulated and observed LHC beam backgrounds in the ATLAS experiment at E beam =4 TeV
2018
Results of dedicated Monte Carlo simulations of beam-induced background (BIB) in the ATLAS experiment at the Large Hadron Collider (LHC) are presented and compared with data recorded in 2012. During normal physics operation this background arises mainly from scattering of the 4 TeV protons on residual gas in the beam pipe. Methods of reconstructing the BIB signals in the ATLAS detector, developed and implemented in the simulation chain based on the FLUKA Monte Carlo simulation package, are described. The interaction rates are determined from the residual gas pressure distribution in the LHC ring in order to set an absolute scale on the predicted rates of BIB so that they can be compared qua…
Analysis of Relationship between Net Wage and Consumer Price Index
2013
Abstract In the present paper is presented an econometric analysis of the relationship between net salary and consumer price index. After a brief historical overview will be review the calculating statistics for selected variables and coefficients and will be presented the obtained values. We will study the relationship between variables. It will be realized the cloud of points and will be applied Fisher test. The intensity of selected variables will be study too and some forms of relationship between the two chose variables will be done. Student test is applied. It will be performed the parameter estimation for regression functions and Akaike's criterion will be applied. The homoscedastici…
Highly-parallelized simulation of a pixelated LArTPC on a GPU
2023
The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The alg…
The ALICE experiment at the CERN LHC
2008
Journal of Instrumentation 3(08), S08002 (2008). doi:10.1088/1748-0221/3/08/S08002