Increasing availability through maintainability growth using partial Multi Criteria Decision Making (pMCDM)

In the last decades considerations about equipments' availability became an important issue, as well as its dependence on components characteristics such as reliability and maintainability. This is particularly of outstanding importance if one is dealing with high risk industrial equipments, where these factors play an important and fundamental role in risk management when safety or huge economic values are in discussion. As availability is a function of reliability, maintainability, and maintenance support activities, the main goal is to improve one or more of these factors. This paper intends to show how maintainability can influence availability and present a methodology to select the most important attributes for maintainability using a partial Multi Criteria Decision Making (pMCDM). Improvements in maintainability can be analyzed assuming it as a probability related with a restore probability density function [g(t)]

Mean-field analysis of the majority-vote model broken-ergodicity steady state

We study analytically a variant of the one-dimensional majority-vote model in which the individual retains its opinion in case there is a tie among the neighbors' opinions. The individuals are fixed in the sites of a ring of size $L$ and can interact with their nearest neighbors only. The interesting feature of this model is that it exhibits an infinity of spatially heterogeneous absorbing configurations for $L \to \infty$ whose statistical properties we probe analytically using a mean-field framework based on the decomposition of the $L$-site joint probability distribution into the $n$-contiguous-site joint distributions, the so-called $n$-site approximation. To describe the broken-ergodicity steady state of the model we solve analytically the mean-field dynamic equations for arbitrary time $t$ in the cases n=3 and 4. The asymptotic limit $t \to \infty$ reveals the mapping between the statistical properties of the random initial configurations and those of the final absorbing configurations. For the pair approximation ($n=2$) we derive that mapping using a trick that avoids solving the full dynamics. Most remarkably, we find that the predictions of the 4-site approximation reduce to those of the 3-site in the case of expectations involving three contiguous sites. In addition, those expectations fit the Monte Carlo data perfectly and so we conjecture that they are in fact the exact expectations for the one-dimensional majority-vote model

Petrography and geochemistry of Sepeda Li-rich aplite-pegmatite dyke swarm (Montalegre, N Portugal)

The Sepeda aplite-pegmatite dyke swarm is situated in the Barroso-Alvão region (Montalegre, Northern Portugal) and is currently a strategic Li ore deposit in Europe. Geologically, it is located in the Parautochthonous Thrust Complex of the Galicia-Trás-os-Montes Zone (Variscan Iberian Belt), more exactly on its southern edge, next to the Central-Iberian Zone. Numerous aplitic and pegmatitic bodies, considered of the LCT type (e.g. Noronha et al., 2013), that cross cut the host metasediments of Silurian age were recently targeted in a diamond drilling campaign. From 4 drill hole logs with suspected Li mineralizations, 120 samples were selected for whole-rock chemical analysis and also 13 samples for thin section preparation. Petrographically, the Sepeda pegmatitic rocks are characterized by distinctive igneous textures that include the following major crystalline phases: K-feldspar, plagioclase, quartz, muscovite, petalite and spodumene. The latter is commonly altered to other Li bearing minerals such as eucryptite and cookeite. The most common accessory minerals are the phosphates montebrasite and apatite and the opaques cassiterite and sphalerite. Aditionally, there are strong evidence of solid state deformation like the dynamic recrystalization of quartz and bent muscovites in addition to plagioclase and K-feldspar flexured twins. In relation to whole-rock geochemistry, these intrusive rocks are mainly felsic with SiO2 contents ranging between 60,97 and 85,78%. The lithologies of intermediate compositions are mostly the aplitic types occuring at shallower depths. With regards to Li2O, the concentration interval varies from 0,01 up to 4,13% where the richer samples (>1% of Li2O) are the pegmatites with aproximately 74% of Si2O in which petalite is the major constituent. Other relevant trace element is Sn reaching 2100 ppm in opposition to Cs (1,68 - 191,50 ppm) and Ta (1,10 - 97,40 ppm). They also show low concentrations in ΣREE (1,37 - 5,61 ppm) with strongly variable Eu anomalies (0,36 ≤ Eu/Eu* ≤ 2,98).publishe

New series expansions for the H-function of communication theory

The H-function of communication theory plays an important role in the error rate analysis in digital communication with the presence of additive white Gaussian noise (AWGN) and generalized multipath fading conditions. In this paper we investigate several convergent and/or asymptotic expansions of Hp(z,b,η) for some limiting values of their variables and parameters: large values of z, large values of p, small values of η, and values of b→1. We provide explicit and/or recursive algorithms for the computation of the coefficients of the expansions. Some numerical examples illustrate the accuracy of the approximations

Asymptotic approximation of a highly oscillatory integral with application to the canonical catastrophe integrals

We consider the highly oscillatory integral () ∶= ∫ ∞ −∞ (+2+) () for large positive values of , − < ≤ , and positive integers with 1 ≤ ≤ , and () an entire function. The standard saddle point method is complicated and we use here a simplified version of this method introduced by López et al. We derive an asymptotic approximation of this integral when → +∞ for general values of and in terms of elementary functions, and determine the Stokes lines. For ≠ 1, the asymptotic behavior of this integral may be classified in four different regions according to the even/odd character of the couple of parameters and ; the special case =1 requires a separate analysis. As an important application, we consider the family of canonical catastrophe integrals Ψ(1, 2,…,) for large values of one of its variables, say , and bounded values of the remaining ones. This family of integrals may be written in the form () for appropriate values of the parameters , and the function (). Then, we derive an asymptotic approximation of the family of canonical catastrophe integrals for large ||. The approximations are accompanied by several numerical experiments. The asymptotic formulas presented here fill up a gap in the NIST Handbook of Mathematical Functions by Olver et al

Uniform convergent expansions of the error function in terms of elementary functions

We derive a new analytic representation of the error function erf z in the form of a convergent series whose terms are exponential and rational functions. The expansion holds uniformly in z in the double sector | arg(±z)| < π/4. The expansion is accompanied by realistic error bounds

Orthogonal basis for the optical transfer function

We propose systems of orthogonal functions qn to represent optical transfer functions (OTF) characterized by including the diffraction-limited OTF as the first basis function q0 = OTFperfect. To this end, we apply a powerful and rigorous theoretical framework based on applying the appropriate change of variables to well-known orthogonal systems. Here we depart from Legendre polynomials for the particular case of rotationally symmetric OTF and from spherical harmonics for the general case. Numerical experiments with different examples show that the number of terms necessary to obtain an accurate linear expansion of the OTF mainly depends on the image quality. In the rotationally symmetric case we obtained a reasonable accuracy with approximately 10 basis functions, but in general, for cases of poor image quality, the number of basis functions may increase and hence affect the efficiency of the method. Other potential applications, such as new image quality metrics are also discussed.Ministerio de Economía y Competitividad (MINECO) (MTM2014-52859-P, FIS2014-58303-P).Peer Reviewe

Colonization of rice and Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae) larvae by genetically modified endophytic Methylobacterium mesophilicum

The colonization of Spodoptera frugiperda J.E. Smith larvae and rice seedlings by genetically modified endophytic bacterium Methylobacterium mesophilicum, and also the possible transfer of this bacterium to inside the larva's body during seedlings consumption were studied. The data obtained by bacterial reisolation and fluorescence microscopy showed that the bacterium colonized the rice seedlings, the larva's body and that the endophytic bacteria present in seedlings could be acquired by the larvae. In that way, the transference of endophytic bacterium from plants to insect can be a new and important strategy to insect control using engineered microorganisms.CNPq National Council of Researc

Saline stress and cell toxicity evaluation using suspended plant cell cultures of horticultural crops grown in a bioreactor

Crop salt damage consists, usually, of leaf burn and defoliation, and it is associated with accumulation of toxic levels of sodium and/or chloride in leaf cells (Storey and Walker, 1999). The cell and tissue culture are simple biological systems that offer a direct approach to the metabolic changes. The plant cell growth in a controlled environment, as a bioreactor, is a unique tool for cell ion transport studies. Cell suspension culture of citrus cell line was exposed to a medium containing different sodium chloride concentrations (0mM, 42.7mM and 85.5mM). The growth profile of control cells (absence of NaCl) and 85.5mM cells were similar. The lack of inhibition of biomass accumulation, of all tested saline conditions clearly showed that the level of NaCl concentration used was not toxic for the cell metabolism. Also its ability to resist to 85.5mM NaCl can be on evidence that this suspension cel culture might have salt tolerance characteristics

Context aware advisor for public transportation

This paper presents an Android-based mobile app designed to provide real time context aware public transportation information and advice to its users through the combination of the user's preferences and geographic context with data retrieved from a public transportation information system called XTraN Passenger. Thus, this mobile app contributes to fulfill the necessities of the passengers, and also provides an incentive for people to use the public transportation infrastructure more frequently. The proposed mobile app allows the users to benefit from the access to real time public transportation data in a simple and intuitive way. The validation of the features and operation of the developed app was assessed with results from use cases and real-world experimental tests using public transportation data from a Brazilian bus fleet operator.This work is supported by FCT with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 –Programa Operacional Competitividade e Internacionalização (POCI) with the reference project POCI-01-0145-FEDER-006941