Vertex component analysis: a geometric-based approach to unmix hyperspectral data

Hyperspectral remote sensing exploits the electromagnetic scattering patterns of the different materials at specific wavelengths [2, 3]. Hyperspectral sensors have been developed to sample the scattered portion of the electromagnetic spectrum extending from the visible region through the near-infrared and mid-infrared, in hundreds of narrow contiguous bands [4, 5]. The number and variety of potential civilian and military applications of hyperspectral remote sensing is enormous [6, 7]. Very often, the resolution cell corresponding to a single pixel in an image contains several substances (endmembers) [4]. In this situation, the scattered energy is a mixing of the endmember spectra. A challenging task underlying many hyperspectral imagery applications is then decomposing a mixed pixel into a collection of reflectance spectra, called endmember signatures, and the corresponding abundance fractions [8–10]. Depending on the mixing scales at each pixel, the observed mixture is either linear or nonlinear [11, 12]. Linear mixing model holds approximately when the mixing scale is macroscopic [13] and there is negligible interaction among distinct endmembers [3, 14]. If, however, the mixing scale is microscopic (or intimate mixtures) [15, 16] and the incident solar radiation is scattered by the scene through multiple bounces involving several endmembers [17], the linear model is no longer accurate. Linear spectral unmixing has been intensively researched in the last years [9, 10, 12, 18–21]. It considers that a mixed pixel is a linear combination of endmember signatures weighted by the correspondent abundance fractions. Under this model, and assuming that the number of substances and their reflectance spectra are known, hyperspectral unmixing is a linear problem for which many solutions have been proposed (e.g., maximum likelihood estimation [8], spectral signature matching [22], spectral angle mapper [23], subspace projection methods [24,25], and constrained least squares [26]). In most cases, the number of substances and their reflectances are not known and, then, hyperspectral unmixing falls into the class of blind source separation problems [27]. Independent component analysis (ICA) has recently been proposed as a tool to blindly unmix hyperspectral data [28–31]. ICA is based on the assumption of mutually independent sources (abundance fractions), which is not the case of hyperspectral data, since the sum of abundance fractions is constant, implying statistical dependence among them. This dependence compromises ICA applicability to hyperspectral images as shown in Refs. [21, 32]. In fact, ICA finds the endmember signatures by multiplying the spectral vectors with an unmixing matrix, which minimizes the mutual information among sources. If sources are independent, ICA provides the correct unmixing, since the minimum of the mutual information is obtained only when sources are independent. This is no longer true for dependent abundance fractions. Nevertheless, some endmembers may be approximately unmixed. These aspects are addressed in Ref. [33]. Under the linear mixing model, the observations from a scene are in a simplex whose vertices correspond to the endmembers. Several approaches [34–36] have exploited this geometric feature of hyperspectral mixtures [35]. Minimum volume transform (MVT) algorithm [36] determines the simplex of minimum volume containing the data. The method presented in Ref. [37] is also of MVT type but, by introducing the notion of bundles, it takes into account the endmember variability usually present in hyperspectral mixtures. The MVT type approaches are complex from the computational point of view. Usually, these algorithms find in the first place the convex hull defined by the observed data and then fit a minimum volume simplex to it. For example, the gift wrapping algorithm [38] computes the convex hull of n data points in a d-dimensional space with a computational complexity of O(nbd=2cþ1), where bxc is the highest integer lower or equal than x and n is the number of samples. The complexity of the method presented in Ref. [37] is even higher, since the temperature of the simulated annealing algorithm used shall follow a log( ) law [39] to assure convergence (in probability) to the desired solution. Aiming at a lower computational complexity, some algorithms such as the pixel purity index (PPI) [35] and the N-FINDR [40] still find the minimum volume simplex containing the data cloud, but they assume the presence of at least one pure pixel of each endmember in the data. This is a strong requisite that may not hold in some data sets. In any case, these algorithms find the set of most pure pixels in the data. PPI algorithm uses the minimum noise fraction (MNF) [41] as a preprocessing step to reduce dimensionality and to improve the signal-to-noise ratio (SNR). The algorithm then projects every spectral vector onto skewers (large number of random vectors) [35, 42,43]. The points corresponding to extremes, for each skewer direction, are stored. A cumulative account records the number of times each pixel (i.e., a given spectral vector) is found to be an extreme. The pixels with the highest scores are the purest ones. N-FINDR algorithm [40] is based on the fact that in p spectral dimensions, the p-volume defined by a simplex formed by the purest pixels is larger than any other volume defined by any other combination of pixels. This algorithm finds the set of pixels defining the largest volume by inflating a simplex inside the data. ORA SIS [44, 45] is a hyperspectral framework developed by the U.S. Naval Research Laboratory consisting of several algorithms organized in six modules: exemplar selector, adaptative learner, demixer, knowledge base or spectral library, and spatial postrocessor. The first step consists in flat-fielding the spectra. Next, the exemplar selection module is used to select spectral vectors that best represent the smaller convex cone containing the data. The other pixels are rejected when the spectral angle distance (SAD) is less than a given thresh old. The procedure finds the basis for a subspace of a lower dimension using a modified Gram–Schmidt orthogonalizati on. The selected vectors are then projected onto this subspace and a simplex is found by an MV T pro cess. ORA SIS is oriented to real-time target detection from uncrewed air vehicles using hyperspectral data [46]. In this chapter we develop a new algorithm to unmix linear mixtures of endmember spectra. First, the algorithm determines the number of endmembers and the signal subspace using a newly developed concept [47, 48]. Second, the algorithm extracts the most pure pixels present in the data. Unlike other methods, this algorithm is completely automatic and unsupervised. To estimate the number of endmembers and the signal subspace in hyperspectral linear mixtures, the proposed scheme begins by estimating sign al and noise correlation matrices. The latter is based on multiple regression theory. The signal subspace is then identified by selectin g the set of signal eigenvalue s that best represents the data, in the least-square sense [48,49 ], we note, however, that VCA works with projected and with unprojected data. The extraction of the end members exploits two facts: (1) the endmembers are the vertices of a simplex and (2) the affine transformation of a simplex is also a simplex. As PPI and N-FIND R algorithms, VCA also assumes the presence of pure pixels in the data. The algorithm iteratively projects data on to a direction orthogonal to the subspace spanned by the endmembers already determined. The new end member signature corresponds to the extreme of the projection. The algorithm iterates until all end members are exhausted. VCA performs much better than PPI and better than or comparable to N-FI NDR; yet it has a computational complexity between on e and two orders of magnitude lower than N-FINDR. The chapter is structure d as follows. Section 19.2 describes the fundamentals of the proposed method. Section 19.3 and Section 19.4 evaluate the proposed algorithm using simulated and real data, respectively. Section 19.5 presents some concluding remarks.

China's space program : a new tool for PRC "soft power" in international relations?

When China launched an anti-satellite (ASAT) weapon in January 2007 to destroy one of its inactive weather satellites, most reactions from academics and U.S. space experts focused on a potential military “space race” between the United States and China. Overlooked, however, is China’s growing role as global competitor on the non-military side of space. China’s space program goes far beyond military counterspace applications and manifests manned space aspirations, including lunar exploration. Its pursuit of both commercial and scientific international space ventures constitutes a small, yet growing, percentage of the global space launch and related satellite service industry. It also highlights China’s willingness to cooperate with nations far away from Asia for political and strategic purposes. These partnerships may constitute a challenge to the United States and enhance China’s “soft power” among key American allies and even in some regions traditionally dominated by U.S. influence (e.g., Latin America and Africa). Thus, an appropriate U.S. response may not lie in a “hard power” counterspace effort but instead in a revival of U.S. space outreach of the past, as well as implementation of more business-friendly export control policies.

Environmental pressures and impacts of public sector organizations: the case of the Portuguese Military

Progress in Industrial Ecology, An International Journal, nº 4(5), p. 363-381

Developing and implementing an environmental performance index for the Portuguese military

Business Strategy and the Environment nº 15, p. 71–86

Technology market transfer plan launch of DELIVES to E.U. Market©

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Biotecnologia

Adenoviruses isolated from civilian and military personnel in the city of Rio de Janeiro, Brazil

Adenovirus are important pathogen primarily associated to respiratory infections of children and military personnel, even though it is also associated to cases of conjunctivitis and keratoconjunctivitis. We analyzed respiratory secretion collected from subjects with and without respiratory infection symptoms, being 181 civilians and 221 military subjects. The samples were inoculated in HEp-2 and/or A549 tissue cultures for viral isolation. Samples presenting cytopathogenic effect (CPE) in any tissue culture were tested by a polymerase chain reaction (PCR) assay to confirm adenovirus isolation. The isolates confirmed as adenovirus were further analyzed by restriction endonuclease assay for determination of viral species. Three isolates were identified as specie A (two from civilian and one from military), one isolate from military was identified as specie C, and one isolate from civilian was identified as specie D. For two isolates the specie could not be identified.

Integração Energética da Unidade de Pré-destilação U-0100 da Fábrica de Aromáticos

A presente dissertação foi realizada no âmbito do Mestrado em Engenharia Química no ramo de Otimização Energética na Indústria Química, do Instituto Superior de Engenharia do Porto. O estudo energético foi desenvolvido na empresa Petrogal, S.A, na Refinaria de Matosinhos, avaliando a possível racionalização energética do processo existente na Fábrica de Aromáticos. Os objetivos propostos basearam-se na realização de uma integração energética à unidade de pré-destilação, denominada por U-0100, que se encontra instalada na Fábrica de Aromáticos. Pretende-se, de uma forma geral, o reaproveitamento máximo da energia do processo, diminuindo o recurso a utilidades externas. Para tal recorreu-se à metodologia da análise do ponto de estrangulamento, designada por tecnologia Pinch. Numa primeira fase da otimização foi necessário conhecer todo o processo em causa e os conceitos associados à tecnologia aplicada. Após contactar com o processo procedeu-se ao levantamento energético do mesmo, referente ao ano 2013. Nesta etapa foram recolhidos todos os dados considerados relevantes para a quantificação energética das correntes e das utilidades empregues. Depois da recolha efetuou-se a integração energética estabelecendo um ∆Tmin ótimo para o processo de 5°C, após uma prévia análise da influência deste parâmetro sobre os consumos. Constatou-se que atualmente o processo de separação opera com uma taxa de recuperação energética de 16,8% da energia total, sendo a restante energia introduzida por utilidades externas. Com a análise do ponto de estrangulamento concluiu-se que a unidade de pré - destilação U-0100 se encontra integrada energeticamente, não sendo essencial proceder a qualquer modificação à mesma. No entanto sugere-se como trabalho futuro um estudo técnico e económico da implementação de um pré-aquecedor de ar, necessário ao processo de combustão que se dá na fornalha H-0101. Isto tendo em vista o reaproveitamento máximo da corrente, gases de combustão, que é desperdiçada para o meio ambiente.

Encurvadura em vigas mistas: estudo do modelo em “U” invertido

Dissertação para obtenção do Grau de Mestre em Engenharia Civil – Perfil Estruturas

Tradição e tradução: festa e etnicidade entre os imigrantes açorianos nos E.U.A.

O autor analisa a recriação das Festas dos Espírito Santo pelas comunidades açorianas dos E.U.A. na viragem do século XXI, nomeadamente a tensão entre fidelidade à tradição e inovação. A retórica tradicionalista e etnomimética coexiste com um conjunto de adaptações ao novo contexto social e cultural. Nas sociabilidades subjacentes à Festa, o protagonismo de círculos sociais da terra de origem - a família, o parentesco, a freguesia - convive com a importância das novas identidades forjadas na imigração.

Tension-Free Vaginal Tape (T.V.T) - Nova e Revolucionária Técnica para o Tratamento Cirúrgico da Incontinência Urinária de Esforço (I.U.E.) Feminina Introduzida na MAC pelo Núcleo de Ginecologia Urológica

Este artigo pretende fazer uma revisão de uma das últimas e inovadoras alternativas cirúrgicas viáveis para a cura da incontinência urinária de esforço feminina, com um sucesso superior a 86%. É uma cirurgia mini invasiva e que induz um suporte da uretra média livre de tensão, muito eficaz. Tem vantagens, poucas complicações, curto tempo operatório e benefícios para a doente no pós-operatório imediato e tardio.

Tradição e tradução: festa e etnicidade entre os imigrantes açorianos nos E.U.A.

Desde finais do século XIX que se desenvolveu, nos estados norte- -americanos de Massachusetts (MA) e de Rhode Island (RI), uma importante comunidade de origem portuguesa. De acordo com o censo norte-americano de 1990, essa comunidade é composta por um total de 320.000 pessoas de portuguese ancestry. Tendo sido freqüentemente descrita como uma minoria étnica "invisível" (cf Smith, 1978), ela tem entretanto uma presença importante em cidades como Fali River e New Bedford - no sudeste de Massachusetts - ou East Providence - Rhode Island - onde representa entre 40 a 55% da população total. Chegada aos EUA em duas vagas sucessivas - a primeira situada entre 1870 e 1930, a segunda entre 1960 e 1980 - esta comunidade é originária, em cerca de 90% dos casos, do arquipélago dos Açores. Dada esta sua ascendência açoriana, os imigrantes portugueses nos EUA mantêm laços importantes com a cultura do arquipélago, que, como se sabe, ao mesmo tempo que possui bastantes pontes com a cultura portuguesa mais geral, apresenta também inúmeras particularidades.

Incidência de hepatite por sôro homólogo no Hospital das Clínicas da F.M.U.F.Pe.

Os autores estudaram mensalmente e por um período de seis meses 62 pacientes através de exames clínico-laboratoriais e que receberam transfusão de sangue no Hospital das Clínicas da F.M.U.F.Pe. Constataram em 3 deles sinais clínicos-laboratoriais e histopatológicos de hepatite por vírus (hepatite por sóro homólogo). Após revisão da literatuta recomendam que os estudos prossigam a fim de que os riscos de transmissão da hepatite pós-transfusional sejam eliminados.

Incindência de Himenolepíase nana e Taenia sp. no Instituto de Medicina Tropical da U. F. Pernambuco no período de 1968 a 1970

Os Autores realizando um levantamento coproparasitológico no Instituto de Medicina Tropical da U.F.Pe., com relação a incidência de Hymenolepis nana e Taenia sp no período de 1968 a 1970, encontram índice de infestação muito baixo, em tôrno de 0,05% a 2,7% para Taenia sp e 0,36% para Hymenolepis nana.

Treasury bond returns and U.S. political cycles

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Finance from the NOVA – School of Business and Economics