589 research outputs found
VisualPDE: rapid interactive simulations of partial differential equations
Computing has revolutionised the study of complex nonlinear systems, both by
allowing us to solve previously intractable models and through the ability to
visualise solutions in different ways. Using ubiquitous computing
infrastructure, we provide a means to go one step further in using computers to
understand complex models through instantaneous and interactive exploration.
This ubiquitous infrastructure has enormous potential in education, outreach
and research. Here, we present VisualPDE, an online, interactive solver for a
broad class of 1D and 2D partial differential equation (PDE) systems. Abstract
dynamical systems concepts such as symmetry-breaking instabilities, subcritical
bifurcations and the role of initial data in multistable nonlinear models
become much more intuitive when you can play with these models yourself, and
immediately answer questions about how the system responds to changes in
parameters, initial conditions, boundary conditions or even spatiotemporal
forcing. Importantly, VisualPDE is freely available, open source and highly
customisable. We give several examples in teaching, research and knowledge
exchange, providing high-level discussions of how it may be employed in
different settings. This includes designing web-based course materials
structured around interactive simulations, or easily crafting specific
simulations that can be shared with students or collaborators via a simple URL.
We envisage VisualPDE becoming an invaluable resource for teaching and research
in mathematical biology and beyond. We also hope that it inspires other efforts
to make mathematics more interactive and accessible.Comment: 19 pages, 7 figures. This is a companion paper to the website
https://visualpde.com
A chromatic transient visual evoked potential based encoding/decoding approach for brain-computer interface
This paper presents a new encoding/decoding approach to brain-computer interface (BCI) based on chromatic transient visual evoked potential (CTVEP). The proposed CTVEP-based encoding/decoding approach is designed to provide a safer and more comfortable stimulation method than the conventional VEP-based stimulation methods for BCI without loss of efficiency. For this purpose, low-frequency isoluminant chromatic stimuli are time-encoded to serve as different input commands for BCI control, and the superior comfortableness of the proposed stimulation method is validated by a survey. A combination of diversified signal processing techniques are further employed to decode the information from CTVEP. Based on experimental results, a properly designed configuration of the CTVEP-based stimulation method and a tailored signal processing framework are developed. It is demonstrated that high performance (at information transfer rate: 58.0 bits/min, accuracy: 94.9%, false alarm rate: 1.3%) for BCI can be achieved by means of the CTVEP-based encoding/decoding approach. It turns out that to achieve such good performance, only simple signal processing algorithms with very low computational complexity are required, which makes the method suitable for the development of a practical BCI system. A preliminary prototype of such a system has been implemented with demonstrated applicability. © 2011 IEEE.published_or_final_versio
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