951 resultados para vector auto-regressive model


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We report on a new vector model of an erbium doped fiber laser mode locked with carbon nanotubes. This model goes beyond the limitations of the previously used models based on either coupled nonlinear Schrödinger or Ginzburg-Landau equations. It results in a new family of vector solitons with fast evolving states of polarization experimentally observed in our previous papers.

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Background: Allergy is a form of hypersensitivity to normally innocuous substances, such as dust, pollen, foods or drugs. Allergens are small antigens that commonly provoke an IgE antibody response. There are two types of bioinformatics-based allergen prediction. The first approach follows FAO/WHO Codex alimentarius guidelines and searches for sequence similarity. The second approach is based on identifying conserved allergenicity-related linear motifs. Both approaches assume that allergenicity is a linearly coded property. In the present study, we applied ACC pre-processing to sets of known allergens, developing alignment-independent models for allergen recognition based on the main chemical properties of amino acid sequences.Results: A set of 684 food, 1,156 inhalant and 555 toxin allergens was collected from several databases. A set of non-allergens from the same species were selected to mirror the allergen set. The amino acids in the protein sequences were described by three z-descriptors (z1, z2 and z3) and by auto- and cross-covariance (ACC) transformation were converted into uniform vectors. Each protein was presented as a vector of 45 variables. Five machine learning methods for classification were applied in the study to derive models for allergen prediction. The methods were: discriminant analysis by partial least squares (DA-PLS), logistic regression (LR), decision tree (DT), naïve Bayes (NB) and k nearest neighbours (kNN). The best performing model was derived by kNN at k = 3. It was optimized, cross-validated and implemented in a server named AllerTOP, freely accessible at http://www.pharmfac.net/allertop. AllerTOP also predicts the most probable route of exposure. In comparison to other servers for allergen prediction, AllerTOP outperforms them with 94% sensitivity.Conclusions: AllerTOP is the first alignment-free server for in silico prediction of allergens based on the main physicochemical properties of proteins. Significantly, as well allergenicity AllerTOP is able to predict the route of allergen exposure: food, inhalant or toxin. © 2013 Dimitrov et al.; licensee BioMed Central Ltd.

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As one of the most popular deep learning models, convolution neural network (CNN) has achieved huge success in image information extraction. Traditionally CNN is trained by supervised learning method with labeled data and used as a classifier by adding a classification layer in the end. Its capability of extracting image features is largely limited due to the difficulty of setting up a large training dataset. In this paper, we propose a new unsupervised learning CNN model, which uses a so-called convolutional sparse auto-encoder (CSAE) algorithm pre-Train the CNN. Instead of using labeled natural images for CNN training, the CSAE algorithm can be used to train the CNN with unlabeled artificial images, which enables easy expansion of training data and unsupervised learning. The CSAE algorithm is especially designed for extracting complex features from specific objects such as Chinese characters. After the features of articficial images are extracted by the CSAE algorithm, the learned parameters are used to initialize the first CNN convolutional layer, and then the CNN model is fine-Trained by scene image patches with a linear classifier. The new CNN model is applied to Chinese scene text detection and is evaluated with a multilingual image dataset, which labels Chinese, English and numerals texts separately. More than 10% detection precision gain is observed over two CNN models.

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Background: DNA-binding proteins play a pivotal role in various intra- and extra-cellular activities ranging from DNA replication to gene expression control. Identification of DNA-binding proteins is one of the major challenges in the field of genome annotation. There have been several computational methods proposed in the literature to deal with the DNA-binding protein identification. However, most of them can't provide an invaluable knowledge base for our understanding of DNA-protein interactions. Results: We firstly presented a new protein sequence encoding method called PSSM Distance Transformation, and then constructed a DNA-binding protein identification method (SVM-PSSM-DT) by combining PSSM Distance Transformation with support vector machine (SVM). First, the PSSM profiles are generated by using the PSI-BLAST program to search the non-redundant (NR) database. Next, the PSSM profiles are transformed into uniform numeric representations appropriately by distance transformation scheme. Lastly, the resulting uniform numeric representations are inputted into a SVM classifier for prediction. Thus whether a sequence can bind to DNA or not can be determined. In benchmark test on 525 DNA-binding and 550 non DNA-binding proteins using jackknife validation, the present model achieved an ACC of 79.96%, MCC of 0.622 and AUC of 86.50%. This performance is considerably better than most of the existing state-of-the-art predictive methods. When tested on a recently constructed independent dataset PDB186, SVM-PSSM-DT also achieved the best performance with ACC of 80.00%, MCC of 0.647 and AUC of 87.40%, and outperformed some existing state-of-the-art methods. Conclusions: The experiment results demonstrate that PSSM Distance Transformation is an available protein sequence encoding method and SVM-PSSM-DT is a useful tool for identifying the DNA-binding proteins. A user-friendly web-server of SVM-PSSM-DT was constructed, which is freely accessible to the public at the web-site on http://bioinformatics.hitsz.edu.cn/PSSM-DT/.

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In this study it is shown that the nontrivial hyperbolic fixed point of a nonlinear dynamical system, which is formulated by means of the adaptive expectations, corresponds to the unstable equilibrium of Harrod. We prove that this nonlinear dynamical (in the sense of Harrod) model is structurally stable under suitable economic conditions. In the case of structural stability, small changes of the functions (C1-perturbations of the vector field) describing the expected and the true time variation of the capital coefficients do not influence the qualitative properties of the endogenous variables, that is, although the trajectories may slightly change, their structure is the same as that of the unperturbed one, and therefore these models are suitable for long-time predictions. In this situation the critique of Lucas or Engel is not valid. There is no topological conjugacy between the perturbed and unperturbed models; the change of the growth rate between two levels may require different times for the perturbed and unperturbed models.

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A szerzők cikke az etnocentrikus érzelmek hatását mutatja be a hazai és a külföldi termékek megítélésére. Empirikus kutatásaikra és regressziós modelljeikre támaszkodva felvázolják azt a hatásmechanizmust, amely a szakirodalomba a fogyasztói etnocentrizmus néven vonult be. Megállapítják, hogy másképp hatnak a patrióta és a nacionalista érzelmek a hazai és a külföldi termékek iránti attitűdökre. Míg a hazai termékeknél egy karakterisztikus, többdimenziós kép tárul elénk, addig a cseh, kanadai és német termékek megítéléséből általánosított, külföldi termékek esetében csak a termékkel való azonosulást tudták kiemelni. A megkérdezettek demográfiai jellemzői közül egyedül a férfiak mutattak statisztikailag azonos irányú és erősségű kapcsolatot a hazai és a külföldi termékek megítélésénél. _______________________ The authors’ article presents effects of the ethnocentric emotion of the appreciation of the domestic and foreign goods. Based on their empirical and regressive models they feature that effectmechanism, which is named consumer ethnocentrism in the special literature. They set that the patriot and the nationalist emotions acting differently on attitudes of the domestic and the foreign goods.

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A pulse–pulse interaction that leads to rogue wave (RW) generation in lasers was previously attributed either to soliton–soliton or soliton–dispersive-wave interaction. The beating between polarization modes in the absence of a saturable absorber causes similar effects. Accounting for these polarization modes in a laser resonator is the purpose of the distributed vector model of laser resonators. Furthermore, high pump power, high amplitude, and short pulse duration are not necessary conditions to observe pulse attraction, repulsion, and collisions and the resonance exchange of energy between among them. The regimes of interest can be tuned just by changing the birefringence in the cavity with the pump power slightly higher than the laser threshold. This allows the observation of a wide range of RW patterns in the same experiment, as well as to classify them. The dynamics of the interaction between pulses leads us to the conclusion that all of these effects occur due to nonlinearity induced by the inverse population in the active fiber as well as an intrinsic nonlinearity in the passive part of the cavity. Most of the mechanisms of pulse–pulse interaction were found to be mutually exclusive. This means that all the observed RW patterns, namely, the “lonely,” “twins,” “three sisters,” and “cross,” are probably different cases of the same process.

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This paper presents an extension to the energy vector, well known in the Ambisonics literature, to improve its predictions of localisation at off-centre listening positions. In determining the source direction, a perceptual weight is assigned to each loudspeaker gain, taking into account the relative arrival times, levels, and directions of the loudspeaker signals. The proposed model is evaluated alongside the original energy vector and two binaural models through comparison with the results of recent perceptual studies. The extended version was found to provide results that were at least 50% more accurate than the second best predictor for two experiments involving off-centre listeners with first- and third-order Ambisonics systems.

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This paper presents the first multi vector energy analysis for the interconnected energy systems of Great Britain (GB) and Ireland. Both systems share a common high penetration of wind power, but significantly different security of supply outlooks. Ireland is heavily dependent on gas imports from GB, giving significance to the interconnected aspect of the methodology in addition to the gas and power interactions analysed. A fully realistic unit commitment and economic dispatch model coupled to an energy flow model of the gas supply network is developed. Extreme weather events driving increased domestic gas demand and low wind power output were utilised to increase gas supply network stress. Decreased wind profiles had a larger impact on system security than high domestic gas demand. However, the GB energy system was resilient during high demand periods but gas network stress limited the ramping capability of localised generating units. Additionally, gas system entry node congestion in the Irish system was shown to deliver a 40% increase in short run costs for generators. Gas storage was shown to reduce the impact of high demand driven congestion delivering a reduction in total generation costs of 14% in the period studied and reducing electricity imports from GB, significantly contributing to security of supply.

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Motivated by environmental protection concerns, monitoring the flue gas of thermal power plant is now often mandatory due to the need to ensure that emission levels stay within safe limits. Optical based gas sensing systems are increasingly employed for this purpose, with regression techniques used to relate gas optical absorption spectra to the concentrations of specific gas components of interest (NOx, SO2 etc.). Accurately predicting gas concentrations from absorption spectra remains a challenging problem due to the presence of nonlinearities in the relationships and the high-dimensional and correlated nature of the spectral data. This article proposes a generalized fuzzy linguistic model (GFLM) to address this challenge. The GFLM is made up of a series of “If-Then” fuzzy rules. The absorption spectra are input variables in the rule antecedent. The rule consequent is a general nonlinear polynomial function of the absorption spectra. Model parameters are estimated using least squares and gradient descent optimization algorithms. The performance of GFLM is compared with other traditional prediction models, such as partial least squares, support vector machines, multilayer perceptron neural networks and radial basis function networks, for two real flue gas spectral datasets: one from a coal-fired power plant and one from a gas-fired power plant. The experimental results show that the generalized fuzzy linguistic model has good predictive ability, and is competitive with alternative approaches, while having the added advantage of providing an interpretable model.

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Motivated by environmental protection concerns, monitoring the flue gas of thermal power plant is now often mandatory due to the need to ensure that emission levels stay within safe limits. Optical based gas sensing systems are increasingly employed for this purpose, with regression techniques used to relate gas optical absorption spectra to the concentrations of specific gas components of interest (NOx, SO2 etc.). Accurately predicting gas concentrations from absorption spectra remains a challenging problem due to the presence of nonlinearities in the relationships and the high-dimensional and correlated nature of the spectral data. This article proposes a generalized fuzzy linguistic model (GFLM) to address this challenge. The GFLM is made up of a series of “If-Then” fuzzy rules. The absorption spectra are input variables in the rule antecedent. The rule consequent is a general nonlinear polynomial function of the absorption spectra. Model parameters are estimated using least squares and gradient descent optimization algorithms. The performance of GFLM is compared with other traditional prediction models, such as partial least squares, support vector machines, multilayer perceptron neural networks and radial basis function networks, for two real flue gas spectral datasets: one from a coal-fired power plant and one from a gas-fired power plant. The experimental results show that the generalized fuzzy linguistic model has good predictive ability, and is competitive with alternative approaches, while having the added advantage of providing an interpretable model.

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Introdução: Uma relação de vinculação segura implica a presença de um modelo representacional das figuras de vinculação como “disponíveis” e capazes de proporcionar protecção e que a qualidade dos cuidados parentais precoce é fundamental a determinar a saúde mental dos indivíduos. Se esta relação assume um enorme relevância para a saúde mental de qualquer ser humano, a institucionalização de crianças/jovens, envolvendo ameaças em termos da disponibilidade das figuras de vinculação constitui uma condição propícia para atrasos de desenvolvimento e aumento da probabilidade do desenvolvimento de sintomatologia psicopatológica. Os objectivos deste estudo passam, então, por analisar as diferenças na vinculação, mas também na auto-estima, de jovens institucionalizados vs nãoinstitucionalizados. Metodologia: A nossa amostra é constituída por 223 jovens nãoinstitucionalizados de duas escolas do Concelho de Coimbra (média de idades M=15.3; desvio-padrão, DP=1.97) e 47 jovens institucionalizados (M=15.5 DP=1.93). Tanto os jovens institucionalizados como não-institucionalizados preencheram um questionário com questões sóciodemográficas, relacionais, escolares, de saúde e bem-estar (com pequenas particularidades em algumas variáveis conforme a sub-amostra), o Inventory of Parent Attachment (IPPA) e a Rosenberg Self-Esteem Scale (RSES). A sub-amostra de jovens institucionalizados respondeu ainda a questões sobre a sua adaptação/vivência ao/no Lar. Resultados: Os rapazes da amostra não institucionalizada apresentam uma pontuação média mais elevada de auto-estima vs. raparigas. Nos jovens institucionalizados não foram encontradas diferenças de género a este nível. Não existem diferenças de género, em ambas as sub-amostras, na pontuação total do IPPA e suas dimensões. Os rapazes nãoinstitucionalizados vs. institucionalizados não divergem na pontuação média total de autoestima. O mesmo sucede com as raparigas. Ambas as sub-amostras não divergem na pontuação média total do IPPA e suas dimensões. Na amostra não-institucionalizada quer nos rapazes, quer nas raparigas não existem diferenças na pontuação total média na RSES, entre os jovens mais novos vs. mais velhos. Na amostra institucionalizada também não se verificam diferenças na pontuação total na RSES por idades. Nos jovens não institucionalizados foram encontradas diferenças na pontuação total média no IPPA (e suas dimensões, à excepção da Alienação), por idade, com os mais novos a apresentarem sempre valores médios mais elevados. Na amostra institucionalizada estas diferenças não se verificaram. Nos rapazes e raparigas da amostra não-institucionalizada verificaram-se associações significativas entre a pontuação na RSES e no IPPA e em todas as suas dimensões. O mesmo se verificou na subamostra institucionalizada. Não existe uma associação significativa entre a pertença a dada sub-amostra e a pertença ao grupo “pouco seguro” vs. “muito seguro”. Apesar de outras associações terem sido encontradas, importa reforçar as associações significativas entre a pontuação na auto-estima e na vinculação total e suas dimensões (quer nos rapazes e raparigas não-institucionalizados, como na amostra institucionalizada) e variáveis como a sintomatologia depressiva, a sintomatologia ansiosa e algumas variáveis relacionais. Discussão/Conclusão: De um modo geral parecem não existir diferenças entre jovens nãoinstitucionalizados vs. institucionalizados em termos de vinculação e de auto-estima. Porém, a uma vinculação insegura e uma menor auto-estima associam-se piores outcomes (e.g. sintomatologia depressiva) em ambas as amostras. Os profissionais trabalhando com adolescentes não-institucionalizados ou institucionalizados devem preocupar-se em avaliar a sua auto-estima e vinculação, procurando, eventualmente, nelas intervir terapeuticamente. / Introduction: It is well kown that a secure attachment relation implies the presence of representational model of the attachment figures as being available and able to provide protection and that the quality of earlier parental care is crucial in determining subjects mental health and there developmental trajectories. If this relation assumes such a big relevance to the mental health of any human being, the institutionalization of children/adolescents, even when truly needed, involving threats in terms of the availability of attachment figures constitutes a condition that might lead to developmental delays and might increase the probability of psychopathological sintomatology developing. The aims of this study are, then, to analyze if there are attachment differences and, also, in self-esteem, between a sub-sample of non-institutionalized and institutionalized adolescents. Methodology: Our sample comprises 223 adolescents non-institutionalized from two schools of Coimbra Council (mean age, M=15.3; standard deviation, SD=1.97) and 47 institutionalized adolescents (M=15.5 SD=1.93). Both sub-samples filled in a questionnaire with sociodemographic, relational, about school, health and well-being questions (with small particularities in some variables, regarding each sub-sample), the Inventory of Parent Attachment (IPPA) and the Rosenberg Self-Esteem Scale (RSES). Institutionalized adolescents also answered questions about the adaptation/life to/in the institution. Results: Boys from the non-institutionalized sub-sample present an higher self-esteem mean score vs. girls. We did not find significant gender differences in self-esteem mean score in the subsample of institutionalized adolescents. There are no gender differences, in both sub-samples, in IPPA (and all its dimensions) total score. Non-institutionalized boys vs. institutionalized boys do not differ in their self-esteem mean score. The same is valid for girls. Both subsamples do not differ in their IPPA (and all its dimensions) mean score. In the noninstitutionalized sample, either in boys, either in girls there are no differences regarding total RSES mean score, between younger (12-15 years old) and older (16-20 years old) adolescents. In the institutionalized sample there were also no differences regarding this score, by age groups. In the non-institutionalized sub-sample we found differences in IPPA total mean score (an in all its dimensions, with the exception of Alienation), by age, with younger adolescents presenting always higher mean scores. In the institutionalized sample there were no differences. Both in boys and girls from the non-institutionalized sample there were significant associations between RSES score and IPPA (and all its dimensions) score. The same result was found in the total institutionalized sample. Although other significant associations were found, we must reinforce the presence of significant associations between self-esteem score and IPPA total score (and of its dimensions) (either in boys and girls noninstitutionalized, either in the institutionalized sub-sample) and variables such as lifetime and depressive symptomatology in the last two weeks, anxious symptomatology in the last two weeks and some relational variables. Discussion/Conclusion: In general, we did not found significant differences between non-institutionalized vs. institutionalized adolescents in terms of attachment and self-esteem. However, a secure attachment and a lower self-esteem are associated with worst outcomes (e.g. depressive symptomatology) in both samples. Professionals working with adolescents, either or not institutionalized must assess their selfesteem and attachment and might, eventually, intervene on these aspects therapeutically.

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According to law number 12.715/2012, Brazilian government instituted guidelines for a program named Inovar-Auto. In this context, energy efficiency is a survival requirement for Brazilian automotive industry from September 2016. As proposed by law, energy efficiency is not going to be calculated by models only. It is going to be calculated by the whole universe of new vehicles registered. In this scenario, the composition of vehicles sold in market will be a key factor on profits of each automaker. Energy efficiency and its consequences should be taken into consideration in all of its aspects. In this scenario, emerges the following question: which is the efficiency curve of one automaker for long term, allowing them to adequate to rules, keep balancing on investment in technologies, increasing energy efficiency without affecting competitiveness of product lineup? Among several variables to be considered, one can highlight the analysis of manufacturing costs, customer value perception and market share, which characterizes this problem as a multi-criteria decision-making. To tackle the energy efficiency problem required by legislation, this paper proposes a framework of multi-criteria decision-making. The proposed framework combines Delphi group and Analytic Hierarchy Process to identify suitable alternatives for automakers to incorporate in main Brazilian vehicle segments. A forecast model based on artificial neural networks was used to estimate vehicle sales demand to validate expected results. This approach is demonstrated with a real case study using public vehicles sales data of Brazilian automakers and public energy efficiency data.

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This paper reports some experiments in using SVG (Scalable Vector Graphics), rather than the browser default of (X)HTML/CSS, as a potential Web-based rendering technology, in an attempt to create an approach that integrates the structural and display aspects of a Web document in a single XML-compliant envelope. Although the syntax of SVG is XML based, the semantics of the primitive graphic operations more closely resemble those of page description languages such as PostScript or PDF. The principal usage of SVG, so far, is for inserting complex graphic material into Web pages that are predominantly controlled via (X)HTML and CSS. The conversion of structured and unstructured PDF into SVG is discussed. It is found that unstructured PDF converts into pages of SVG with few problems, but difficulties arise when one attempts to map the structural components of a Tagged PDF into an XML skeleton underlying the corresponding SVG. These difficulties are not fundamentally syntactic; they arise largely because browsers are innately bound to (X)HTML/CSS as their default rendering model. Some suggestions are made for ways in which SVG could be more totally integrated into browser functionality, with the possibility that future browsers might be able to use SVG as their default rendering paradigm.