Search results for " Signal Processing"
showing 10 items of 208 documents
Identifying Geographic Terms within Natural Language Text
2008
Masteroppgave i informasjons- og kommunikasjonsteknologi 2008 – Universitetet i Agder, Grimstad The huge amount of textual data available in digital form in today’s world increases the need for methods that facilitate ease of access and navigability. Automatic extraction of keywords from text bodies is one promising approach. However, the relevance of keywords are context dependent, and extracting relevant keywords often requires a semantic analysis, simply because words may have different meanings in different contexts. It is well-known that resolving such word sense ambiguity automatically can be very challenging. When the topic of interest is geographic information, important keywords wo…
WLAN 802.11 b/g interference into ZigBee networks
2008
Masteroppgave i informasjons- og kommunikasjonsteknologi 2008 – Universitetet i Agder, Grimstad ZigBee network as a low rate wireless personal area network (LR-WPANs) developed very fast nowadays. Since both ZigBee network and WLAN (802.11b/g) operate in the 2.4GHz unlicensed industrial scientific medical (ISM) frequency band, signal interference is possible to exist and result in signal degradation when devices are collocated in the same environment. This thesis analyzes, simulates and measures the interference and evaluates ZigBee network performance under the WLAN interference in terms of Packet Error Rate (PER) and Packet Loss Ratio (PLR). And the investigation emphasis of this thesis i…
Accurate Measurement and Visualization of Traffic Load in IEEE 802.11 WLANs
2008
Masteroppgave i informasjons- og kommunikasjonsteknologi 2008 – Universitetet i Agder, Grimstad Wireless Local Area Networks (WLANs) based on the IEEE 802.11 standard are getting very popular these days, due to their support for new multimedia services and VoIP, and because WLANs are appearing on more and more small devices. This causes a steadily increasing load and becomes a challenge to network administrators who want to make their WLANs run efficiently and to keep the users satisfied. This Master thesis addresses the lack of efficient and affordable monitoring tools for those running WLANs, by developing an accurate method and for the visualization of traffic patterns and bandwidth util…
Modelling of the Universe : Simulation of the GPS (The Global Positioning System)
2007
Masteroppgave i informasjons- og kommunikasjonsteknologi 2007 – Høgskolen i Agder, Grimstad ParAbel is a project at Agder University College aims at mathematics and physics on Internet. One of the sub projects named SimReal [2] (Simulation in ‘Realfag’), which currently aims at simulating behaviours and properties of universe for both mathematics and physics studying. This project focuses on simulation of the GPS which is one sub task in SimReal. In this paper, on the one hand, we will set up a GPS simulation model and use it to be a teaching material for learning mathematics and physics. On the other hand, by testing the simulation model among the college students, we will discuss about th…
The human-computer connection: An overview of brain-computer interfaces
2018
This article introduces the field of brain-computer interfaces (BCI), which allows the control of devices without the generation of any active motor output but directly from the decoding of the user’s brain signals. Here we review the current state of the art in the BCI field, discussing the main components of such an interface and illustrating ongoing research questions and prototypes for controlling a large variety of devices, from virtual keyboards for communication to robotics systems to replace lost motor functions and even clinical interventions for motor rehabilitation after a stroke. The article concludes with some insights into the future of BCI.
Input-Output Finite-Time Stability of Discrete-Time Impulsive Switched Linear Systems with State Delays
2013
Published version of an article in the journal: Circuits, Systems, and Signal Processing. Also available from the publisher at: http://dx.doi.org/10.1007/s00034-013-9610-7 This paper is concerned with the problem of input-output finite-time stability (IO-FTS) for discrete impulsive switched systems with state delays. Sufficient conditions are presented for the existence of IO-FTS for such systems under the cases of certain switching, arbitrary switching, and uncertain switching. All the obtained results are formulated in a set of linear matrix inequalities (LMIs). Two numerical examples are given to illustrate the effectiveness of the proposed results.
Inverse Scattering Solutions with Applications to Electromagnetic Signal Processing
2009
When a signal is recorded that has been physically generated by some scattering process (the interaction of electromagnetic, acoustic or elastic waves with inhomogeneous materials, for example), the ‘standard model’ for the signal (i.e. information content convolved with a characteristic Impulse Response Function) is usually based on a single scattering approximation. An additive noise term is introduced into the model to take into account a range of non-deterministic factors including multiple scattering that, along with electronic noise and other background noise sources, is assumed to be relatively weak. Thus, the standard model is based on a ‘weak field condition’ and the inverse scatte…
U-Rail laser-based ultrasonic inspection system prototype "system overview and status"
2006
Fast Decentralized Linear Functions via Successive Graph Shift Operators
2019
Decentralized signal processing performs learning tasks on data distributed over a multi-node network which can be represented by a graph. Implementing linear transformations emerges as a key task in a number of applications of decentralized signal processing. Recently, some decentralized methods have been proposed to accomplish that task by leveraging the notion of graph shift operator, which captures the local structure of the graph. However, existing approaches have some drawbacks such as considering special instances of linear transformations, or reducing the family of transformations by assuming that a shift matrix is given such that a subset of its eigenvectors spans the subspace of i…
Digital signal processing for relaxation data conversion
2005
Abstract The origins, philosophy and basic practical aspects are considered for an approach of digital data transformations for broadband dielectric relaxation spectroscopy and other relaxation experiments carrying out direct and inverse integral transforms with kernels depending on the ratio or product of arguments. The approach is based on the concept that the mentioned data transformations represent a filtering problem on a logarithmic scale allowing one to implement the transforms by digital functional filters with the logarithmic sampling. As an example, digital Kramers–Kronig transformers are considered.