980 resultados para Modified Bessel Function


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The elastic behavior of the demand consumption jointly used with other available resources such as distributed generation (DG) can play a crucial role for the success of smart grids. The intensive use of Distributed Energy Resources (DER) and the technical and contractual constraints result in large-scale non linear optimization problems that require computational intelligence methods to be solved. This paper proposes a Particle Swarm Optimization (PSO) based methodology to support the minimization of the operation costs of a virtual power player that manages the resources in a distribution network and the network itself. Resources include the DER available in the considered time period and the energy that can be bought from external energy suppliers. Network constraints are considered. The proposed approach uses Gaussian mutation of the strategic parameters and contextual self-parameterization of the maximum and minimum particle velocities. The case study considers a real 937 bus distribution network, with 20310 consumers and 548 distributed generators. The obtained solutions are compared with a deterministic approach and with PSO without mutation and Evolutionary PSO, both using self-parameterization.

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A novel sensitive electrochemical sensor was developed by electropolymerization of pyrrole(PY)and molecularly imprinted polymer (MIP)which was synthesized onto a glassy carbon electrode (GCE) in aqueous solution using cyclic voltammetry in the presence of Trimethoprim (TMP) as template molecules. Furthermore,a previous electrode modification was performed by deposition of a suspension of graphene on the electrode's surface. The performance of the imprinted and non-imprinted (NIP) films was evaluated by impedance spectroscopy (EIS) and cyclic voltammetry (CV) of a ferric solution. The molecularly imprinted film exhibited a high selectivity and sensitivity toward TMP. The sensor presented a linear range, between peak current intensity and logarithm of TMP concentration between 1.0x10-6 and 1.0x10-4 M. The results were accurate (with recoveries higher than 94%), precise (with standard deviations less than 5%) and the detection limit was 1.3x10-7 M. The new sensor is selective, simple to construct and easy to operate. The MIP sensor was successfully applied to quantify TMP in urinesamples.

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Thermally expandable particles (TEPs) are used in a wide variety of applications by industry mainly for weight reduction and appearance improvement for thermoplastics, inks, and coatings. In adhesive bonding, TEPs have been used for recycling purposes. However, TEPs might be used to modify structural adhesives for other new purposes, such as: to increase the joint strength by creating an adhesive functionally modified along the overlap of the joint by gradual heating and/or to heal the adhesive in case of damage. In this study, the behaviour of a structural polyurethane adhesive modified with TEPs was investigated as a preliminary study for further investigations on the potential of TEPs in adhesive joints. Tensile bulk tests were performed to get the tensile properties of the unmodified and TEPs-modified adhesive, while Double Cantilever Beam (DCB) test was performed in order to evaluate the resistance to mode I crack propagation of unmodified and TEPs-modified adhesive. In addition, in order to investigate the behaviour of the particles while encapsulated in adhesives, a thermal analysis was done. Scanning electron microscopy (SEM) was used to examine the fracture surface morphology of the specimens. The fracture toughness of the TEPs-modified adhesive was found to increase by addition of TEPs, while the adhesive tensile strength at yield decreased. The temperature where the particles show the maximum expansion varied with TEPs concentration, decreasing with increasing the TEPs content.

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Depression, the most prevalent psychiatric disorder, has a lifelong risk of 20% and is related to high rates of death among the patients. Thus, this study aims to conduct a systematic review of changes in executive functions of adult patients diagnosed with depression. We found 1381 articles; however, only 28 were selected and recovered. The inclusion criteria was the assessment of executive functions with at least one neuropsychological test, and articles that evaluated primarily adult individuals with depression, without comparison to other psychiatric disorders. Although most of the studies (25 out of 28 analyzed) have shown deficits in some executive subcomponents, these findings are not conclusive because they used different parameters of assessment. Moreover, many variables were not controlled, such as the different subtypes of the disorder, the high level of severity, comorbidity and the use of drugs. Most studies showed different deficits in executive functions in depressed patients, but further longitudinal studies are needed in order to confirm these findings.

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In this paper we address the problem of computing multiple roots of a system of nonlinear equations through the global optimization of an appropriate merit function. The search procedure for a global minimizer of the merit function is carried out by a metaheuristic, known as harmony search, which does not require any derivative information. The multiple roots of the system are sequentially determined along several iterations of a single run, where the merit function is accordingly modified by penalty terms that aim to create repulsion areas around previously computed minimizers. A repulsion algorithm based on a multiplicative kind penalty function is proposed. Preliminary numerical experiments with a benchmark set of problems show the effectiveness of the proposed method.

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In the last decade, local image features have been widely used in robot visual localization. In order to assess image similarity, a strategy exploiting these features compares raw descriptors extracted from the current image with those in the models of places. This paper addresses the ensuing step in this process, where a combining function must be used to aggregate results and assign each place a score. Casting the problem in the multiple classifier systems framework, in this paper we compare several candidate combiners with respect to their performance in the visual localization task. For this evaluation, we selected the most popular methods in the class of non-trained combiners, namely the sum rule and product rule. A deeper insight into the potential of these combiners is provided through a discriminativity analysis involving the algebraic rules and two extensions of these methods: the threshold, as well as the weighted modifications. In addition, a voting method, previously used in robot visual localization, is assessed. Furthermore, we address the process of constructing a model of the environment by describing how the model granularity impacts upon performance. All combiners are tested on a visual localization task, carried out on a public dataset. It is experimentally demonstrated that the sum rule extensions globally achieve the best performance, confirming the general agreement on the robustness of this rule in other classification problems. The voting method, whilst competitive with the product rule in its standard form, is shown to be outperformed by its modified versions.

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Recently simple limiting functions establishing upper and lower bounds on the Mittag-Leffler function were found. This paper follows those expressions to design an efficient algorithm for the approximate calculation of expressions usual in fractional-order control systems. The numerical experiments demonstrate the superior efficiency of the proposed method.

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Dissertation presented to obtain the PhD degree in Biochemistry at the Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa

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This paper proposes a PSO based approach to increase the probability of delivering power to any load point by identifying new investments in distribution energy systems. The statistical failure and repair data of distribution components is the main basis of the proposed methodology that uses a fuzzyprobabilistic modeling for the components outage parameters. The fuzzy membership functions of the outage parameters of each component are based on statistical records. A Modified Discrete PSO optimization model is developed in order to identify the adequate investments in distribution energy system components which allow increasing the probability of delivering power to any customer in the distribution system at the minimum possible cost for the system operator. To illustrate the application of the proposed methodology, the paper includes a case study that considers a 180 bus distribution network.

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RESUMO: A monitorização da actividade física diária nos doentes com Doença Pulmonar Obstrutiva Crónica (DPOC) tem sido alvo de grande interesse nos últimos tempos. No entanto, ainda nenhum estudo reuniu o conjunto de factores – grau de obstrução, hiperinsuflação pulmonar, alteração das trocas gasosas, dispneia, dessaturação de oxigénio, capacidade de exercício, ansiedade e depressão – que podem afectar a sua realização, nem os correlacionou com os dados obtidos com o pedómetro e que reflectem o que cada doente realmente faz no seu dia-adia. O presente estudo teve como objectivo principal identificar os factores que influenciam a actividade física na vida diária dos doentes com DPOC. Estudaram-se 55 doentes do sexo masculino com idade média de 67 anos e um FEV1 médio de 50,8% do previsto, com DPOC moderada a muito grave (estadios II a IV), de entre os utentes do Laboratório de Fisiopatologia Respiratória do Centro Hospitalar de Torres Vedras. Avaliaram-se os parâmetros da escala de dispneia modificada do Medical Research Council (MMRC), escala London Chest Activity of Daily Living (LCADL), escala de Ansiedade e Depressão Hospitalar (HADS), índice BODE, estudo funcional respiratório em repouso, teste de marcha de seis minutos e o número de passos por dia utilizando um pedómetro por um período de três dias. Observou-se que os doentes deram em média 4972 passos por dia e apresentaram uma cotação total média de 17,7 na LCADL, tendo existido diferenças estatisticamente significativas em função da gravidade da doença, sendo que os doentes mais graves são os que em média andam menos no seu dia-a-dia e apresentam maior limitação na realização das actividades de vida diária. O número de passos por dia apresentou correlações significativas com as variáveis idade, dispneia, depressão, hiperinsuflação monar, gravidade de obstrução (FEV1), trocas gasosas (DLCO), saturação arterial de oxigénio mínima e correlação mais forte com a distância percorrida no TM6m. Este estudo permitiu identificar que os factores determinantes da actividade física na vida diária de doentes com DPOC nos estadios II a IV, foram a dispneia e a distância percorrida no TM6m. Além disso, estes doentes constituem um grupo sedentário, particularmente a partir do estadio III, com níveis de actividade física diária baixos.-----------ABSTRACT There has been an increased interest in monitoring the daily physical activity in patients with Chronic Obstructive Pulmonary Disease (COPD). However, no specific study has been realized so far that has put the different factors which can affect the results obtained altogether, (such as the degree of obstruction, pulmonary hyperinflation, abnormal gas exchange, dyspnea, oxygen desaturation, exercise capacity, anxiety and depression) or correlated with data obtained from the pedometer, which reflect each patient actual activity in their daily life. This study aimed to identify the main factors that influence physical activity in daily life of patients with COPD. The scope of this study was 55 male patients with an average age of 67 years old and an average FEV1 of 50.8% predicted, with moderate to severe COPD (stages II to IV), among patients from the Respiratory Pathophysiology Laboratory of the Centro Hospitalar de Torres Vedras. Were evaluated the parameters of the modified Medical Research Council dyspnea scale (MMRC), London Chest Activity of Daily Living scale (LCADL), Hospital Anxiety and Depression scale (HADS), BODE index, pulmonary function test at rest, six minute walk test (6MWT) and the number of steps per day using a pedometer for a period of three days. It was observed that patients have walked an average of 4972 steps per day and had a total score of 17.7 at LCADL, and statistically significant differences were stated depending on the severity of the disease. Whereas patients with a more severe degree of the disease have walked least in their daily life and show greater restraint in carrying out activities of daily living. The number of steps per day showed significant correlations with age, dyspnea, depression, lung hyperinflation, severity of obstruction (FEV1), gas exchange (DLCO), minimum arterial oxygen saturation and stronger correlation with distance walked on 6MWT. This study shows that the crucial factors of physical activity in daily life of COPD patients at stages II to IV were dyspnea and distance on 6MWT. Moreover, these patients constitute a sedentary group, particularly from the stage III, with lower levels of daily physical activity.

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Dissertação para obtenção do Grau de Mestre em Genética Molecular e Biomedicina

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Dissertação para obtenção do Grau de Mestre em Genética Molecular e Biomedicina

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A new immunosensor is presented for human chorionic gonadotropin (hCG), made by electrodepositing chitosan/gold-nanoparticles over graphene screen-printed electrode (SPE). The antibody was covalently bound to CS via its Fc-terminal. The assembly was controlled by electrochemical Impedance Spectroscopy (EIS) and followed by Fourier Transformed Infrared (FTIR). The hCG-immunosensor displayed linear response against the logarithm-hCG concentration for 0.1–25 ng/mL with limit of detection of 0.016 ng/mL. High selectivity was observed in blank urine and successful detection of hCG was also achieved in spiked samples of real urine from pregnant woman. The immunosensor showed good detection capability, simplicity of fabrication, low-cost, high sensitivity and selectivity.