Constrained least square pre-distortion scheme for multiuser ultra-wideband

The study proposes a constrained least square (CLS) pre-distortion scheme for multiple-input single-output (MISO) multiple access ultra-wideband (UWB) systems. In such a scheme, a simple objective function is defined, which can be efficiently solved by a gradient-based algorithm. For the performance evaluation, scenarios CM1 and CM3 of the IEEE 802.15.3a channel model are considered. Results show that the CLS algorithm has a fast convergence and a good trade-off between intersymbol interference (ISI) and multiple access interference (MAI) reduction and signal-to-noise ratio (SNR) preservation, performing better than time-reversal (TR) pre-distortion.

Experimental Investigation of the Hydrodynamic Coefficients of a Remotely Operated Vehicle Using a Planar Motion Mechanism

The determination of hydrodynamic coefficients of full scale underwater vehicles using system identification (SI) is an extremely powerful technique. The procedure is based on experimental runs and on the analysis of on-board sensors and thrusters signals. The technique is cost effective and it has high repeatability; however, for open-frame underwater vehicles, it lacks accuracy due to the sensors' noise and the poor modeling of thruster-hull and thruster-thruster interaction effects. In this work, forced oscillation tests were undertaken with a full scale open-frame underwater vehicle. These conducted tests are unique in the sense that there are not many examples in the literature taking advantage of a PMM installation for testing a prototype and; consequently, allowing the comparison between the experimental results and the ones estimated by parameter identification. The Morison's equation inertia and drag coefficients were estimated with two parameter identification methods, that is, the weighted and the ordinary least-squares procedures. It was verified that the in-line force estimated from Morison's equation agrees well with the measured one except in the region around the motion inversion points. On the other hand, the error analysis showed that the ordinary least-squares provided better accuracy and, therefore, was used to evaluate the ratio between inertia and drag forces for a range of Keulegan-Carpenter and Reynolds numbers. It was concluded that, although both experimental and estimation techniques proved to be powerful tools for evaluation of an open-frame underwater vehicle's hydrodynamic coefficients, the research provided a rich amount of reference data for comparison with reduced models as well as for dynamic motion simulation of ROVs. [DOI: 10.1115/1.4004952]

Emprego de ferramentas numéricas na avaliação do módulo de elasticidade em vigas roliças de madeira

Vigas são elementos estruturais encontrados na maioria das construções civis. Dentre os materiais de engenharia, destaca-se a madeira, por ter resistência mecânica satisfatória aliada a baixa densidade. A madeira roliça apresenta-se como boa solução na confecção de vigas, uma vez que não precisa ser processada, como é o caso da madeira serrada. O projeto de elementos estruturais de madeira requer o conhecimento de suas propriedades físicas e mecânicas, obtidas segundo as premissas de documentos normativos. Em se tratando da madeira roliça, os documentos normativos nacionais que tratam da determinação das propriedades de resistência e rigidez estão vigentes há mais de vinte anos sem revisão técnica. De forma geral, tanto as normas nacionais como as internacionais idealizam geometria troncocônica para as peças roliças de madeira, implicando equações simplificadas incapazes de prever a influência das irregularidades da forma na determinação do módulo de elasticidade longitudinal. Este trabalho objetiva avaliar a influência das irregularidades da geometria em peças roliças de madeira Corymbia citriodora e Pinus caribaea no cálculo do módulo de elasticidade longitudinal. Para tanto, utilizou-se do ensaio de flexão estática a três pontos, considerando também um modelo matemático simplificado, assumindo seção circular constante para a forma do elemento. As irregularidades das peças são consideradas nos modelos numéricos, constituídos de elementos finitos de barra e tridimensionais. Os resultados encontrados revelam equivalência estatística entre os módulos de elasticidade para ambas as formas de cálculo, indicando ser plausível a consideração de seção circular constante para as peças de madeira aqui avaliadas.

Utility Harmonic Impedance Measurement Based on Data Selection

Determination of the utility harmonic impedance based on measurements is a significant task for utility power-quality improvement and management. Compared to those well-established, accurate invasive methods, the noninvasive methods are more desirable since they work with natural variations of the loads connected to the point of common coupling (PCC), so that no intentional disturbance is needed. However, the accuracy of these methods has to be improved. In this context, this paper first points out that the critical problem of the noninvasive methods is how to select the measurements that can be used with confidence for utility harmonic impedance calculation. Then, this paper presents a new measurement technique which is based on the complex data-based least-square regression, combined with two techniques of data selection. Simulation and field test results show that the proposed noninvasive method is practical and robust so that it can be used with confidence to determine the utility harmonic impedances.

A study of the anti-plasmodium activity of angiotensin II analogs

Controlling the dissemination of malaria requires the development of new drugs against its etiological agent, a protozoan of the Plasmodium genus. Angiotensin II and its analog peptides exhibit activity against the development of immature and mature sporozoites of Plasmodium gallinaceum. In this study, we report the synthesis and characterization of angiotensin II linear and cyclic analogs with anti-plasmodium activity. The peptides were synthesized by a conventional solid-phase method on Merrifield's resin using the t-Boc strategy, purified by RP-HPLC and characterized by liquid chromatography/ESI (+) MS (LC-ESI(+)/MS), amino acid analysis, and capillary electrophoresis. Anti-plasmodium activity was measured in vitro by fluorescence microscopy using propidium iodine uptake as an indicator of cellular damage. The activities of the linear and cyclic peptides are not significantly different (p < 0.05). Kinetics studies indicate that the effects of these peptides on plasmodium viability overtime exhibit a sigmoidal profile and that the system stabilizes after a period of 1 h for all peptides examined. The results were rationalized by partial least-square analysis, assessing the position-wise contribution of each amino acid. The highest contribution of polar amino acids and a Lys residue proximal to the C-terminus, as well as that of hydrophobic amino acids in the N-terminus, suggests that the mechanism underlying the anti-malarial activity of these peptides is attributed to its amphiphilic character.

Strategies in identifying individuals in a segregant population of common bean and implications of genotype x environment interaction in the success of selection

The objective of this study was to compare the BLUP selection method with different selection strategies in F-2:4 and assess the efficiency of this method on the early choice of the best common bean (Phaseolus vulgaris) lines. Fifty-one F-2:4 progenies were produced from a cross between the CVIII8511 x RP-26 lines. A randomized block design was used with 20 replications and one-plant field plots. Character data on plant architecture and grain yield were obtained and then the sum of the standardized variables was estimated for simultaneous selection of both traits. Analysis was carried out by mixed models (BLUP) and the least squares method to compare different selection strategies, like mass selection, stratified mass selection and between and within progeny selection. The progenies selected by BLUP were assessed in advanced generations, always selecting the greatest and smallest sum of the standardized variables. Analyses by the least squares method and BLUP procedure ranked the progenies in the same way. The coincidence of the individuals identified by BLUP and between and within progeny selection was high and of the greatest magnitude when BLUP was compared with mass selection. Although BLUP is the best estimator of genotypic value, its efficiency in the response to long term selection is not different from any of the other methods, because it is also unable to predict the future effect of the progenies x environments interaction. It was inferred that selection success will always depend on the most accurate possible progeny assessment and using alternatives to reduce the progenies x environments interaction effect.

Ligand- and Structure-Based Drug Design Strategies and PPAR delta/alpha Selectivity

Peroxisome-proliferator-activated receptors are a class of nuclear receptors with three subtypes: a, ? and d. Their main function is regulating gene transcription related to lipid and carbohydrate metabolism. Currently, there are no peroxisome-proliferator-activated receptors d drugs being marketed. In this work, we studied a data set of 70 compounds with a and d activity. Three partial least square models were created, and molecular docking studies were performed to understand the main reasons for peroxisome-proliferator-activated receptors d selectivity. The obtained results showed that some molecular descriptors (log P, hydration energy, steric and polar properties) are related to the main interactions that can direct ligands to a particular peroxisome-proliferator-activated receptors subtype.

Análise de fatores associados ao significado do trabalho

O trabalho tem sido visto não somente como forma de obter a renda, mas também como atividade que proporciona realização pessoal, status social e possibilidade de estabelecer e manter contatos interpessoais, entre outros. Nesta pesquisa, teve-se como objetivo investigar os fatores que influenciam e conferem sentido ao trabalho, como centralidade do trabalho, normas da sociedade e objetivos e resultados valorizados. Na centralidade do trabalho, procurou-se investigar o grau de importância do trabalho dentro do contexto das diversas áreas da vida das pessoas, como família, lazer, religião e vida comunitária. Em normas da sociedade, foram analisados os pontos mais significativos no tocante ao que a sociedade deveria proporcionar ao indivíduo, assim como o que o indivíduo deveria fazer em prol da sociedade. Nos objetivos e resultados valorizados, foi pesquisado o que as pessoas buscam com o trabalho. A partir da pesquisa na literatura, foi elaborado um modelo inicial que, não se mostrando satisfatório segundo critérios estatísticos, foi substituído por outro que apresentou significância estatística e boa aderência aos dados. O modelo escolhido foi o que melhor goodness-of-fit apresentou, quando se utilizou modelagem de equações estruturais pelo método partial least square. O estudo revelou que o significado do trabalho se reflete, na ordem, na centralidade do trabalho, nos objetivos e resultados valorizados e, por último, nas normas sociais.

Fatores de influência no preço do milho no Brasil

Compreender a dinâmica de funcionamento do mercado de milho brasileiro, procedendo a uma investigação dos fatores que afetam as quantidades e preços nesse mercado, é o objetivo deste trabalho. Os testes de raiz unitária foram feitos utilizando-se a metodologia DF-GLS - Dickey Fuller Generalized Least Square - e os de cointegração de Johansen (1988). O modelo estimado, de ajuste pelo preço, foi um Modelo de Autorregressão Vetorial com Correção de Erros - VEC, sendo a identificação feita pelo procedimento de Sims-Bernanke. O estudo permite afirmar que existe forte interação entre os mercados de milho e de soja, mostrando uma relação de complementaridade na oferta e substitutibilidade na demanda, e que fatores macroeconômicos como renda e juros são importantes na determinação dos preços do milho ao produtor e no atacado. Vale ressaltar que os preços externos do milho mostraram relativa importância no processo de formação do preço doméstico do grão.

Lipid and glucose profiles of dairy buffaloes during lactation and dry period

The purpose of this study was to analyze the influence of lactation and dry period in the constituents of lipid and glucose metabolism of buffaloes. One hundred forty-seven samples of serum and plasma were collected between November 2009 and July 2010, from properties raising Murrah, Mediterranean and crossbred buffaloes, located in the State of Sao Paulo, Brazil. Biochemical analysis was obtained by determining the contents of serum cholesterol, triglycerides, beta-hydroxybutyrate (β-HBO), non-esterified fatty acids (NEFA) and plasma glucose. Values for arithmetic mean and standard error mean were calculated using the SAS procedure, version 9.2. Tests for normality of residuals and homogeneity of variances were performed using the SAS Guide Data Analysis. Data were analyzed by ANOVA using the SAS procedure Glimmix. The group information (Lactation), Farm and Age were used in the statistical models. Means of groups were compared using Least Square Means (LSMeans) of SAS, where significant difference was observed at P ≤ 0.05. It was possible to conclude that buffaloes during peak lactation need to metabolize body reserves to supplement the lower amounts of bloodstream lipids, when they remain in negative energy balance. In the dry period, there were significant changes in the lipid profile, characterized by decrease of nutritional requirements, with consequent improvement in the general conditions of the animals.

Comparison of multiple-input single-output single-user ultra-wideband systems with pre-distortion

This paper presents a performance analysis of a baseband multiple-input single-output ultra-wideband system over scenarios CM1 and CM3 of the IEEE 802.15.3a channel model, incorporating four different schemes of pre-distortion: time reversal, zero-forcing pre-equaliser, constrained least squares pre-equaliser, and minimum mean square error pre-equaliser. For the third case, a simple solution based on the steepest-descent (gradient) algorithm is adopted and compared with theoretical results. The channel estimations at the transmitter are assumed to be truncated and noisy. Results show that the constrained least squares algorithm has a good trade-off between intersymbol interference reduction and signal-to-noise ratio preservation, providing a performance comparable to the minimum mean square error method but with lower computational complexity. Copyright (C) 2011 John Wiley & Sons, Ltd.

Effect of sample pre-cracking method and notch geometry in plane strain fracture toughness tests as applied to a PMMA resin

The influence of test method factors (notch shape, square or angular, and pre-cracking method, by tapping onto or pressing a razor blade) on the results obtained in plane strain fracture toughness test according to standard ASTM D5045 using SENB specimens made of a commercial PMMA resin were investigated. Results were analyzed quantitatively by comparing the obtained K-IC values and qualitatively by observing their effect on the Moire fringes observed using photoelasticity, showing that, at 95% significance level, the K-IC values are affected by the pre-cracking method, with the most conservative value being obtained when natural pre-cracks were introduced by tapping onto a razor blade (K-IC = 1.15 +/- 0.11 MPa.m(0.5)). This correlates with a perturbation in the stress field close to the pre-crack tip observed in the photoelasticity test sample when it was introduced by pressing the razor blade. Surprisingly, notch geometry only slightly affects the results. (C) 2012 Elsevier Ltd. All rights reserved.

Semi-supervised dimensionality reduction based on partial least squares for visual analysis of high dimensional data

Dimensionality reduction is employed for visual data analysis as a way to obtaining reduced spaces for high dimensional data or to mapping data directly into 2D or 3D spaces. Although techniques have evolved to improve data segregation on reduced or visual spaces, they have limited capabilities for adjusting the results according to user's knowledge. In this paper, we propose a novel approach to handling both dimensionality reduction and visualization of high dimensional data, taking into account user's input. It employs Partial Least Squares (PLS), a statistical tool to perform retrieval of latent spaces focusing on the discriminability of the data. The method employs a training set for building a highly precise model that can then be applied to a much larger data set very effectively. The reduced data set can be exhibited using various existing visualization techniques. The training data is important to code user's knowledge into the loop. However, this work also devises a strategy for calculating PLS reduced spaces when no training data is available. The approach produces increasingly precise visual mappings as the user feeds back his or her knowledge and is capable of working with small and unbalanced training sets.

Gaussian deconvolution: a useful method for a form-free modeling of scattering data from mono- and multilayered planar systems

A new method for analysis of scattering data from lamellar bilayer systems is presented. The method employs a form-free description of the cross-section structure of the bilayer and the fit is performed directly to the scattering data, introducing also a structure factor when required. The cross-section structure (electron density profile in the case of X-ray scattering) is described by a set of Gaussian functions and the technique is termed Gaussian deconvolution. The coefficients of the Gaussians are optimized using a constrained least-squares routine that induces smoothness of the electron density profile. The optimization is coupled with the point-of-inflection method for determining the optimal weight of the smoothness. With the new approach, it is possible to optimize simultaneously the form factor, structure factor and several other parameters in the model. The applicability of this method is demonstrated by using it in a study of a multilamellar system composed of lecithin bilayers, where the form factor and structure factor are obtained simultaneously, and the obtained results provided new insight into this very well known system.

Immunohistochemical evaluation of MMP-2, MMP-9 and CD31/microvascular density in squamous cell carcinomas of the floor of the mouth

The aim of this study was to evaluate the immunoexpression of MMP-2, MMP-9 and CD31/microvascular density in squamous cell carcinomas of the floor of the mouth and to correlate the results with demographic, survival, clinical (TNM staging) and histopathological variables (tumor grade, perineural invasion, embolization and bone invasion). Data from medical records and diagnoses of 41 patients were reviewed. Histological sections were subjected to immunostaining using primary antibodies for human MMP-2, MMP-9 and CD31 and streptavidin-biotin-immunoperoxidase system. Histomorphometric analyses quantified positivity for MMPs (20 fields per slide, 100?points grade, ×200) and for CD31 (microvessels <50?µm in the area of the highest vascularization, 5 fields per slide, 100?points grade, ×400). Statistical design was composed by non-parametric Mann-Whitney U test (investigating the association between numerical variables and immunostainings), chi-square frequency test (in contingency tables), Fisher's exact test (when at least one expected frequency was less than 5 in 2×2 tables), Kaplan-Meier method (estimated probabilities of overall survival) and Iogrank test (comparison of survival curves), all with a significance level of 5%. There was a statistically significant correlation between immunostaining for MMP-2 and lymph node metastasis. Factors associated negatively with survival were N stage, histopathological grade, perineural invasion and immunostaining for MMP-9. There was no significant association between immunoexpression of CD31 and the other variables. The intensity of immunostaining for MMP-2 can be indicative of metastasis in lymph nodes and for MMP-9 of a lower probability of survival