29,711 research outputs found
Universality and Realistic Extensions to the Semi-Analytic Simulation Principle in GNSS Signal Processing
Semi-analytic simulation principle in GNSS signal processing bypasses the bit-true operations at high sampling frequency. Instead, signals at the output branches of the integrate&dump blocks are successfully modeled, thus making extensive Monte Carlo simulations feasible. Methods for simulations of code and carrier tracking loops with BPSK, BOC signals have been introduced in the literature. Matlab toolboxes were designed and published. In this paper, we further extend the applicability of the approach. Firstly, we describe any GNSS signal as a special instance of linear multi-dimensional modulation. Thereby, we state universal framework for classification of differently modulated signals. Using such description, we derive the semi-analytic models generally. Secondly, we extend the model for realistic scenarios including delay in the feed back, slowly fading multipath effects, finite bandwidth, phase noise, and a combination of these. Finally, a discussion on connection of this semi-analytic model and position-velocity-time estimator is delivered, as well as comparison of theoretical and simulated characteristics, produced by a prototype simulator developed at CTU in Prague
M[pi]log, Macromodeling via parametric identification of logic gates
This paper addresses the development of computational models of digital integrated circuit input and output buffers via the identification of nonlinear parametric models. The obtained models run in standard circuit simulation environments, offer improved accuracy and good numerical efficiency, and do not disclose information on the structure of the modeled devices. The paper reviews the basics of the parametric identification approach and illustrates its most recent extensions to handle temperature and supply voltage variations as well as power supply ports and tristate devices
Mesoscale modeling of the rheology of pressure sensitive adhesives through inclusion of transient forces
For optimal application, pressure-sensitive adhesives must have rheological
properties in between those of a viscoplastic solid and those of a viscoelastic
liquid. Such adhesives can be produced by emulsion polymerisation, resulting in
latex particles which are dispersed in water and contain long-chain acrylic
polymers. When the emulsion is dried, the latex particles coalesce and an
adhesive film is formed. The rheological properties of the dried samples are
believed to be dominated by the interface regions between the original latex
particles, but the relation between rheology and latex particle properties is
poorly understood. In this paper we show that it is possible to describe the
bulk rheology of a pressure-sensitive adhesive by means of a mesoscale
simulation model. To reach experimental time and length scales, each latex
particle is represented by just one simulated particle. The model is subjected
to oscillatory shear flow and extensional flow. Simple order of magnitude
estimates of the model parameters already lead to semi-quantitative agreement
with experimental results. We show that inclusion of transient forces in the
model, i.e. forces with memory of previous configurations, is essential to
correctly predict the linear and nonlinear properties.Comment: 29 pages, 8 figure
A Taxonomy of Data Grids for Distributed Data Sharing, Management and Processing
Data Grids have been adopted as the platform for scientific communities that
need to share, access, transport, process and manage large data collections
distributed worldwide. They combine high-end computing technologies with
high-performance networking and wide-area storage management techniques. In
this paper, we discuss the key concepts behind Data Grids and compare them with
other data sharing and distribution paradigms such as content delivery
networks, peer-to-peer networks and distributed databases. We then provide
comprehensive taxonomies that cover various aspects of architecture, data
transportation, data replication and resource allocation and scheduling.
Finally, we map the proposed taxonomy to various Data Grid systems not only to
validate the taxonomy but also to identify areas for future exploration.
Through this taxonomy, we aim to categorise existing systems to better
understand their goals and their methodology. This would help evaluate their
applicability for solving similar problems. This taxonomy also provides a "gap
analysis" of this area through which researchers can potentially identify new
issues for investigation. Finally, we hope that the proposed taxonomy and
mapping also helps to provide an easy way for new practitioners to understand
this complex area of research.Comment: 46 pages, 16 figures, Technical Repor
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