Hyperspectral imagery framework for unmixing and dimensionality estimation

In hyperspectral imagery a pixel typically consists mixture of spectral signatures of reference substances, also called endmembers. Linear spectral mixture analysis, or linear unmixing, aims at estimating the number of endmembers, their spectral signatures, and their abundance fractions. This paper proposes a framework for hyperpsectral unmixing. A blind method (SISAL) is used for the estimation of the unknown endmember signature and their abundance fractions. This method solve a non-convex problem by a sequence of augmented Lagrangian optimizations, where the positivity constraints, forcing the spectral vectors to belong to the convex hull of the endmember signatures, are replaced by soft constraints. The proposed framework simultaneously estimates the number of endmembers present in the hyperspectral image by an algorithm based on the minimum description length (MDL) principle. Experimental results on both synthetic and real hyperspectral data demonstrate the effectiveness of the proposed algorithm.

A didactic sequence of elementary geometric optics Informed by history and philosophy of science

The concepts and instruments required for the teaching and learning of geometric optics are introduced in the didactic processwithout a proper didactic transposition. This claim is secured by the ample evidence of both wide- and deep-rooted alternative concepts on the topic. Didactic transposition is a theory that comes from a reflection on the teaching and learning process in mathematics but has been used in other disciplinary fields. It will be used in this work in order to clear up the main obstacles in the teachinglearning process of geometric optics. We proceed to argue that since Newton���s approach to optics, in his Book I of Opticks, is independent of the corpuscular or undulatory nature of light, it is the most suitable for a constructivist learning environment. However, Newton���s theory must be subject to a proper didactic transposition to help overcome the referred alternative concepts. Then is described our didactic transposition in order to create knowledge to be taught using a dialogical process between students��� previous knowledge, history of optics and the desired outcomes on geometrical optics in an elementary pre-service teacher training course. Finally, we use the scheme-facet structure of knowledge both to analyse and discuss our results as well as to illuminate shortcomings that must be addressed in our next stage of the inquiry.

An integer programming model for the minimum interval graph completion problem

The minimum interval graph completion problem consists of, given a graph G = ( V, E ), ���nding a supergraph H = ( V, E ��� F ) that is an interval graph, while adding the least number of edges |F| . We present an integer programming formulation for solving the minimum interval graph completion problem recurring to a characteri- zation of interval graphs that produces a linear ordering of the maximal cliques of the solution graph.

Aplica����o de um modelo de programa����o linear inteira mista (PLIM) na expans��o da rede de distribui����o de energia el��trica em Angola

Em Angola, apenas cerca de 30% da popula����o tem acesso �� energia el��trica, n��vel que decresce para valores inferiores a 10% em zonas rurais mais remotas. Este problema �� agravado pelo facto de, na maioria dos casos, as infraestruturas existentes se encontrarem danificadas ou n��o acompanharem o desenvolvimento da regi��o. Em particular na capital angolana, Luanda que, sendo a menor prov��ncia de Angola, �� a que regista atualmente a maior densidade populacional. Com uma popula����o de cerca de 5 milh��es de habitantes, n��o s�� h�� frequentemente problemas relacionados com a falha do fornecimento de energia el��trica como h�� ainda uma percentagem consider��vel de munic��pios onde a rede el��trica ainda nem sequer chegou. O governo de Angola, no seu esfor��o de crescimento e aproveitamento das suas enormes potencialidades, definiu o setor energ��tico como um dos fatores cr��ticos para o desenvolvimento sustent��vel do pa��s, tendo assumido que este �� um dos eixos priorit��rios at�� 2016. Existem objetivos claros quanto �� reabilita����o e expans��o das infraestruturas do setor el��trico, aumentando a capacidade instalada do pa��s e criando uma rede nacional adequada, com o intuito n��o s�� de melhorar a qualidade e fiabilidade da rede j�� existente como de a aumentar. Este trabalho de disserta����o consistiu no levantamento de dados reais relativamente �� rede de distribui����o de energia el��trica de Luanda, na an��lise e planeamento do que �� mais premente fazer relativamente �� sua expans��o, na escolha dos locais onde �� vi��vel localizar novas subesta����es, na modela����o adequada do problema real e na proposta de uma solu����o ��tima para a expans��o da rede existente. Depois de analisados diferentes modelos matem��ticos aplicados ao problema de expans��o de redes de distribui����o de energia el��trica encontrados na literatura, optou-se por um modelo de programa����o linear inteira mista (PLIM) que se mostrou adequado. Desenvolvido o modelo do problema, o mesmo foi resolvido por recurso a software de otimiza����o Analytic Solver e CPLEX. Como forma de valida����o dos resultados obtidos, foi implementada a solu����o de rede no simulador PowerWorld 8.0 OPF, software este que permite a simula����o da opera����o do sistema de tr��nsito de pot��ncias.

Dimens��o do sector p��blico e crescimento econ��mico: uma rela����o n��o linear na Uni��o Europeia dos 15?

Os Estados-Membros da Uni��o Europeia t��m tido a preocupa����o de reduzirem a dimens��o da Administra����o P��blica na economia, a par de a tornar muito mais eficiente de forma a promover o crescimento econ��mico. Neste artigo analisam-se as rela����es entre a despesa p��blica e o crescimento econ��mico em 14 Estados-Membros da Uni��o Europeia dos 15, com o objectivo de determinar a dimens��o ��ptima das Administra����es P��blicas, tendo por base te��rica a Curva de Armey. Os resultados, para o per��odo 1965-2007, sugerem uma dimens��o do sector p��blico maximizadora do crescimento econ��mico de 47,37% e 22,17% do PIB, quando avaliada pelas despesas p��blicas totais e o consumo p��blico, respectivamente.

Distributed Linear Precoding and User Selection in Coordinated Multicell Systems

In this manuscript we tackle the problem of semidistributed user selection with distributed linear precoding for sum rate maximization in multiuser multicell systems. A set of adjacent base stations (BS) form a cluster in order to perform coordinated transmission to cell-edge users, and coordination is carried out through a central processing unit (CU). However, the message exchange between BSs and the CU is limited to scheduling control signaling and no user data or channel state information (CSI) exchange is allowed. In the considered multicell coordinated approach, each BS has its own set of cell-edge users and transmits only to one intended user while interference to non-intended users at other BSs is suppressed by signal steering (precoding). We use two distributed linear precoding schemes, Distributed Zero Forcing (DZF) and Distributed Virtual Signalto-Interference-plus-Noise Ratio (DVSINR). Considering multiple users per cell and the backhaul limitations, the BSs rely on local CSI to solve the user selection problem. First we investigate how the signal-to-noise-ratio (SNR) regime and the number of antennas at the BSs impact the effective channel gain (the magnitude of the channels after precoding) and its relationship with multiuser diversity. Considering that user selection must be based on the type of implemented precoding, we develop metrics of compatibility (estimations of the effective channel gains) that can be computed from local CSI at each BS and reported to the CU for scheduling decisions. Based on such metrics, we design user selection algorithms that can find a set of users that potentially maximizes the sum rate. Numerical results show the effectiveness of the proposed metrics and algorithms for different configurations of users and antennas at the base stations.

Integer/fractional decomposition of the impulse response of fractional linear systems

The decomposition of a fractional linear system is discussed in this paper. It is shown that it can be decomposed into an integer order part, corresponding to possible existing poles, and a fractional part. The first and second parts are responsible for the short and long memory behaviors of the system, respectively, known as characteristic of fractional systems.

An Extension of Estimation of Domain of Attraction for Fractional Order Linear System Subject to Saturation Control

This paper employs the Lyapunov direct method for the stability analysis of fractional order linear systems subject to input saturation. A new stability condition based on saturation function is adopted for estimating the domain of attraction via ellipsoid approach. To further improve this estimation, the auxiliary feedback is also supported by the concept of stability region. The advantages of the proposed method are twofold: (1) it is straightforward to handle the problem both in analysis and design because of using Lyapunov method, (2) the estimation leads to less conservative results. A numerical example illustrates the feasibility of the proposed method.

Formula����o fisicamente n��o - linear da teoria generalizada de vigas

Disserta����o para obten����o do grau de Mestre em Engenharia Civil

Optimiza����o estrutural na an��lise n��o linear dos modelos de escoras e tirantes

Disserta����o para obten����o do Grau de Mestre em Engenharia Civil - Perfil Estruturas

Contributo para a modeliza����o de magnetos supercondutores de fluxo residual: aplica����o a um motor linear todo supercondutor

Disserta����o para obten����o do Grau de Mestre em Engenharia Electrot��cnica e de Computadores

On the analysis of data emerging in non-linear and complex systemscomparison of two X-Ray prony spectra

New arguments proving that successive (repeated) measurements have a memory and actually remember each other are presented. The recognition of this peculiarity can change essentially the existing paradigm associated with conventional observation in behavior of different complex systems and lead towards the application of an intermediate model (IM). This IM can provide a very accurate fit of the measured data in terms of the Prony's decomposition. This decomposition, in turn, contains a small set of the fitting parameters relatively to the number of initial data points and allows comparing the measured data in cases where the ���best fit��� model based on some specific physical principles is absent. As an example, we consider two X-ray diffractometers (defined in paper as A- (���cheap���) and B- (���expensive���) that are used after their proper calibration for the measuring of the same substance (corundum a-Al2O3). The amplitude-frequency response (AFR) obtained in the frame of the Prony's decomposition can be used for comparison of the spectra recorded from (A) and (B) - X-ray diffractometers (XRDs) for calibration and other practical purposes. We prove also that the Fourier decomposition can be adapted to ���ideal��� experiment without memory while the Prony's decomposition corresponds to real measurement and can be fitted in the frame of the IM in this case. New statistical parameters describing the properties of experimental equipment (irrespective to their internal ���filling���) are found. The suggested approach is rather general and can be used for calibration and comparison of different complex dynamical systems in practical purposes.

Contributo para o estudo do motor linear s��ncrono supercondutor

Disserta����o para obten����o do Grau de Mestre em Engenharia Electrot��cnica e de Computadores

Non-linear time series models

The last three decades have seen quite dramatic changes the way we modeled time dependent data. Linear processes have been in the center stage in modeling time series. As far as the second order properties are concerned, the theory and the methodology are very adequate.However, there are more and more evidences that linear models are not sufficiently flexible and rich enough for modeling purposes and that failure to account for non-linearities can be very misleading and have undesired consequences.

Analyzing Multiple Outcomes: Is it Really Worth the use of Multivariate Linear Regression?

In health related research it is common to have multiple outcomes of interest in a single study. These outcomes are often analysed separately, ignoring the correlation between them. One would expect that a multivariate approach would be a more efficient alternative to individual analyses of each outcome. Surprisingly, this is not always the case. In this article we discuss different settings of linear models and compare the multivariate and univariate approaches. We show that for linear regression models, the estimates of the regression parameters associated with covariates that are shared across the outcomes are the same for the multivariate and univariate models while for outcome-specific covariates the multivariate model performs better in terms of efficiency.