Simulation Of Interference Effects Research Articles

Semi-classical Monte Carlo algorithm for the simulation of X-ray grating interferometry

Traditional simulation techniques such as wave optics methods and Monte Carlo (MC) particle transport cannot model both interference and inelastic scattering phenomena within one framework. Based on the rules of quantum mechanics to calculate probabilities, we propose a new semi-classical MC algorithm for efficient and simultaneous modeling of scattering and interference processes. The similarities to MC particle transport allow the implementation as a flexible c++ object oriented extension of EGSnrc—a well-established MC toolkit. In addition to previously proposed Huygens principle based transport through optics components, new variance reduction techniques for the transport through gratings are presented as transport options to achieve the required improvement in speed and memory costs necessary for an efficient exploration (system design—dose estimations) of the medical implementation of X-ray grating interferometry (GI), an emerging imaging technique currently subject of tremendous efforts towards clinical translation. The feasibility of simulation of interference effects is confirmed in four academic cases and an experimental table-top GI setup. Comparison with conventional MC transport show that deposited energy features of EGSnrc are conserved.

Simulation of Interference Effects from MB-OFDM and DS-UWB to a QPSK Digital Transmission System

This paper reports on a study of the interference effects from 2 types of ultra wideband (UWB) sources on a QPSK transmission system by simulation. The culprit UWB sources were: multi-band orthogonal frequency-division multiple-access (MB-OFDM) and direct-sequence UWB (DS-UWB), which were modeled on the proposal specifications in the IEEE 802.15.3a to standardize high-speed wireless personal area networks. Average bit error rate (BER) degradation of the victim system was evaluated under in-band interference from the UWB signals. The proposed modified equivalent baseband system was employed in the simulation in order to reduce the simulation costs. Interference effects from the UWB sources were also examined under a Rayleigh fading channel.

Simulation of interference effects in particle streams following impact with a flat surface: Part II. Parametric study and implications for erosion testing and blast cleaning

In a companion paper [Simulation of interference effects in particle streams following impact with a flat surface. Part I. Theory and analysis, submitted for publication], a computer simulation capable of describing the interference between an incident stream of spheres and those rebounding from a flat surface was presented. In the present paper, the model is used to study the effect of the following parameters on the severity of inter-particle collisions: stream angle of incidence, nozzle divergence angle, incident particle velocity, particle size, particle flux, particle–particle and particle–surface impact parameters, and standoff distance. Useful dimensionless parameters are identified and their significance is characterised using a sensitivity analysis. A detailed parametric study of the most important input parameters revealed that interference effects strongly depend not only on flux, but also on angle of attack, standoff distance, coefficient of restitution between particle and surface, and nozzle to particle radius ratio. It is thus important that a full description of experimental conditions in erosion tests be given. Finally, a series of non-dimensional results was presented that can be used to assess the reduction, due to interference effects, in stream power from that available at the nozzle exit. This can be used to estimate how coverage in shot peening, and erosive power in erosion testing, will be affected by interference effects.

Simulation of interference effects in particle streams following impact with a flat surface: Part I. Theory and analysis

The interference between an incident stream of spheres and those rebounding from a flat surface is described using a computer model. The model was capable of examining the effect of the following parameters on the severity and frequency of inter-particle collisions: stream angle of incidence, nozzle divergence angle, incident particle velocity and flux, particle size, particle–particle and particle–surface impact parameters, and stand-off distance. The collision dynamics for systems consisting in excess of 10 4 particles were obtained. Frictionless inter-particle collisions were assumed, but friction for particles impacting the surface was considered. For all collisions, a coefficient of restitution model of impact behaviour was assumed. Dimensionless parameters used to aid in the presentation of the results were identified, and a companion paper [Simulation of interference effects in particle streams following impact with a flat surface. Part II. Parametric study and implications for erosion testing and blast cleaning, submitted for publication] presents a parametric study of their role in erosion testing and blast cleaning processes.