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The aim of this work was to build up a new monitoring technique for the lung preservation. The medical aside problem is to measure the integrity and functionality of the lung tissue, specifically at cellular preservation level in order to improve the survival time until it is grafted. The Impedance monitoring technique for diagnosis edema development is the key in this new technique. The hypothesis...
Several approaches have been developed to define the non-active power concept under nonsinusoidal situations in electrical systems. Nevertheless, these contributions do not provide a complete and satisfactory solution to the non-active power reversibility between frequency domain and time domain. This paper presents a non-active power multivector concept, based on an original vector space frequency-domain...
This paper is a new contribution to the clarification of the non-active power concept. It is based on a Generalized Complex Geometric Algebra (CGn) spanned by a frequency-domain vector space.The classic definition of this quantity is usually associated to the use of the scalar product of voltages and currents rms values. We show that the non-active power can be deduced directly from the power multivector...
The Fourier transform analysis is able to estimate the amplitude and frequency of signals under stationary conditions. For transient or aperiodic signals the Fourier analysis is unable to obtain accurate results and a joint time-frequency analysis must be used to provide simultaneous time and frequency information of transient intervals. A power quality index is proposed for evaluation of both the...
One of the most important aspects of groupware systems is the concept of awareness, which refers to the perception and knowledge of the group and its activities. This paper extends a previously developed ontology-based conceptualization for the development of user interfaces in groupware systems that support awareness. Specifically, we are interested in domain-independent design groupware. We propose...
Pair programming practices usually take place on a single computer where two programmers collaborate, taking on the roles of driver and observer. This article presents COLLECE, a groupware system to support synchronous distributed pair programming practices, and includes a variety of experimental activities in which two groups of programmers were involved to solve various programming problems. The...
This paper addresses the problem of probability estimation in multiclass classification tasks combining two well known data mining techniques: support vector machines and neural networks. We present an algorithm which uses both techniques in a two-step procedure. The first step employs support vector machines within a one-vs-all reduction from multiclass to binary approach to obtain the distances...
A significant number of CSCL (computer-supported collaborative learning) environments support the learning of groups of students enabling their collaboration in solving problems. In this paper, we propose a methodological approach for the design of observation systems in CSCL environments that collect and store all the information required for comprehensive analysis of both the collaboration process...
(N-1)-phase N-wire systems are analyzed into an orthonormal-coordinate system using the fundamental laws of polyphase systems and the condition of zero neutral-current. N-dimension voltage vectors are referenced to a virtual star-point and the current vectors are decomposed into three mutually orthogonal components, two of them are responsible of the active power. Without the condition of zero neutral-current,...
Within groupware systems, collaborative modelling systems play an important role. However, they are difficult to build and domain-specific. In this article we propose the use of the so-called domain-independent modelling systems, which are more flexible and adapt better when new domains appear. We have developed ontologies to support the construction of such systems, defining the domain as well as...
A voltage quality index (VQI) is proposed for evaluation of the voltage quality aspects (QAs) of three-phase voltage signals: instantaneous frequency-deviations, total harmonic distortion and instantaneous symmetrical components. A VQI in the range between 0 to 1 is defined and measured. Accurate measurement of these Qas and VQI are obtained with a virtual instrument: the voltage quality analyzer...
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