Yeso reciclado con residuos de poliestireno expandido y fibra de celulosa para mejorar las propiedades térmicas del yeso

In this study, different proportions of gypsum composite reinforced with recycled cellulose fibers and expanded polystyrene were produced to study the properties of thermal conductivity, density, and flexural strength to be used as sealing plates to improve the thermal comfort of buildings. Different gypsum matrix composites were produced with varied proportions of cellulose fiber and expanded polystyrene, to analyze the influence of residues on the properties of the material. The thermal conductivity obtained for composites with greater amounts of expanded polystyrene was 0.18 W/mK, a 48% reduction in relation to plasterboard, improving thermal performance. The flexural strength was also analyzed, which met the minimum strength requirement for use as gypsum composites, however, it is not enough to be used in places that require mechanical resistance, thus it is indicated for sealing plates applications, improving the thermal performance of places where only plasterboard is used.En este estudio, se produjeron diferentes proporciones de compuesto de yeso reforzado con fibras de celulosa recicladas y poliestireno expandido para estudiar las propiedades de conductividad térmica, densidad y resistencia a la flexión. Se produjeron diferentes composites de matriz de yeso con variadas proporciones de fibra de celulosa y poliestireno expandido, para analizar la influencia de los residuos en las propiedades del material. La conductividad térmica obtenida para los composites con mayores cantidades de poliestireno expandido fue de 0,18 W/mK, una reducción del 48% con relación a las placas de yeso, mejorando el rendimiento térmico. También se analizó la resistencia a la flexión, la cual cumplió con el requisito de resistencia mínima para su uso como compuestos de yeso, sin embargo, no es suficiente para ser utilizado en lugares que requieran resistencia mecánica, por lo que está indicado para aplicaciones de placas de sellado, mejorando el rendimiento térmico de los lugares donde solo se utiliza placa de yeso

H 2 And H ∞ Filtering Design Subject To Implementation Uncertainty

This paper presents new filtering design procedures for discrete-time linear systems. It provides a solution to the problem of linear filtering design, assuming that the filter is subject to parametric uncertainty. The problem is relevant, since the proposed filter design incorporates real world implementation constraints that are always present in practice. The transfer function and the state space realization of the filter are simultaneously computed. The design procedure can also handle plant parametric uncertainty. In this case, the plant parameters are assumed not to be exactly known but belonging to a given convex and closed polyhedron. Robust performance is measured by the H 2 and H ∞ norms of the transfer function from the noisy input to the filtering error. The results are based on the determination of an upper bound on the performance objectives. All optimization problems are linear with constraint sets given in the form of LMI (linear matrix inequalities). Global optimal solutions to these problems can be readily computed. Numerical examples illustrate the theory. © 2005 Society for Industrial and Applied Mathematics.442515530Gevers, M., Li, G., (1993) Parametrizations in Control, Estimation and Filtering Problems, , Springer-Verlag, LondonWilliamson, D., Finite wordlength design of digital Kalman filters for state estimation (1985) IEEE Trans. Automat. Control, 30, pp. 930-939Williamson, D., Kadiman, K., Optimal finite wordlength linear quadratic regulators (1989) IEEE Trans. Automat. Control, 34, pp. 1218-1228Liu, K., Skelton, R.E., Grigoriadis, K., Optimal controllers for finite wordlength implementation (1992) IEEE Trans. Automat. Control, 37, pp. 1294-1304Hwang, S.Y., Minimum uncorrelated unit noise in state-space digital filtering (1977) IEEE Trans. Acoustics Speech Signal Process, 25, pp. 273-281Amit, G., Shaked, U., Minimization of roundoff errors in digital realizations of Kalman filters (1989) IEEE Trans. Acoustics Speech Signal Process, 37, pp. 1980-1982De Oliveira, M.C., Skelton, R.E., Synthesis of controllers with finite precision considerations (2001) Digital Controller Implementation and Fragility: A Modern Perspective, pp. 229-251. , R. S. H. Istepanian and J. F. Whidborne eds., Springer-Verlag, New YorkKeel, L.H., Bhattacharyya, S.P., Robust, fragile or optimal (1997) IEEE Trans. Automat. Control, 42, pp. 1098-1105Keel, L.H., Bhattacharyya, S.P., Authors' reply to: "Comments on 'Robust, fragile or optimal' " by P. M. Mäkilä (1998) IEEE Trans. Automat. Control, 43, p. 1268Dorato, P., Non-fragile controller design: An overview (1998) Proceedings of the 1998 American Control Conference, 5, pp. 2829-2831. , Philadelphia, IEEE, Piscataway, NJFamularo, D., Dorato, P., Abdallah, C.T., Haddad, W.H., Jadbabaie, A., Robust non-fragile LQ controllers: The static state feedback case (2000) Internat. J. Control, 73, pp. 159-165Yang, G.H., Wang, J.L., Robust nonfragile Kalman filtering for uncertain linear systems with estimator gain uncertainty (2001) IEEE Trans. Automat. Control, 46, pp. 343-348Haddad, W.M., Corrado, J.R., Robust resilient dynamic controllers for systems with parametric uncertainty and controller gain variations (2000) Internat. J. Control, 73, pp. 1405-1423Keel, L.H., Bhattacharyya, S.P., Stability margins and digital implementation of controllers (1998) Proceedings of the 1998 American Control Conference, 5, pp. 2852-2856. , (Philadelphia), IEEE, Piscataway, NJGeromel, J.C., Optimal linear filtering under parameter uncertainty (1999) IEEE Trans. Signal Process, 47, pp. 168-175Nesterov, Y., Nemirovskii, A., (1994) Interior-Point Polynomial Algorithms in Convex Programming, , SIAM, PhiladelphiaGeromel, J.C., Bernussou, J., Garcia, G., De Oliveira, M.C., H 2 and H ∞ robust filtering for discrete-time linear systems (2000) SIAM J. Control Optim., 38, pp. 1353-1368Geromel, J.C., De Oliveira, M.C., Bernussou, J., Robust filtering of discrete-time linear systems with parameter dependent Lyapunov functions (2002) SIAM J. Control Optim., 41, pp. 700-711De Oliveira, M.C., Bernussou, J., Geromel, J.C., A new discrete-time robust stability condition (1999) Systems Control Lett., 37, pp. 261-265Sayed, A.H., A framework for state-space estimation with uncertain models (2001) IEEE Trans. Automat. Control, 46, pp. 998-1013Balakrishnan, V., Huang, Y., Packard, A., Doyle, J.C., Linear matrix inequalities in analysis with multipliers (1994) Proceedings of the 1994 American Control Conference, 2, pp. 1228-1232. , Baltimore, MD, IEEE, Piscataway, NJGeromel, J.C., Peres, P.L.D., Bernussou, J., On a convex parameter space method for linear control design of uncertain systems (1991) SIAM J. Control Optim., 29, pp. 381-40

Long Range Anticorrelations and Non-Gaussian Behavior of a Leaky Faucet

We find that intervals between successive drops from a leaky faucet display scale-invariant, long-range anticorrelations characterized by the same exponents of heart beat-to-beat intervals of healthy subjects. This behavior is also confirmed by numerical simulations on lattice and it is faucet-width- and flow-rate-independent. The histogram for the drop intervals is also well described by a L\'evy distribution with the same index for both histograms of healthy and diseased subjects. This additional result corroborates the evidence for similarities between leaky faucets and healthy hearts underlying dynamics.Comment: Self-extracting uuencoded postscript file. Phys.Rev.E (Rap.Comm.). Related papers can be found at http://www.if.uff.br/~tjpp/tjppe.htm

Implementation of the classical plasma–fluid model for simulation of dielectric barrier discharge (DBD) actuators in OpenFOAM

To simulate the coupled plasma and fluid flow physics of dielectric-barrier discharge, a plasma–fluid model is utilized in conjunction with a compressible flow solver. The flow solver is responsible for determining the bulk flow kinetics of dominant neutral background species including mole fractions, gas temperature, pressure and velocity. The plasma solver determines the kinetics and energetics of the plasma species and accounts for finite rate chemistry. In order to achieve maximum reliability and best performance, we have utilized state-of-the-art numerical and theoretical approaches for the simulation of DBD plasma actuators. In this respect, to obtain a stable and accurate solution method, we tested and compared different existing numerical procedures, including operator-splitting algorithm, super-timestepping, and solution of the Poisson and transport equations in a semi-implicit manner. The implementation of the model is conducted in OpenFOAM. Four numerical test cases are considered in order to validate the solvers and to investigate the drawbacks/benefits of the solution approaches. The test problems include single DBD actuator driven by positive, negative and sinusoidal voltage waveforms, similar to the ones that could be found in literature. The accuracy of the results strongly depends to the choice of time step, grid size and discretization scheme. The results indicate that the super-time-stepping treatment improves the computational efficiency in comparison to explicit schemes. However, the semiimplicit treatment of the Poisson and transport equations showed better performance compared to the other tested approaches.info:eu-repo/semantics/publishedVersio

Comparison of DBD plasma actuators flow control authority in different modes of actuation

The principal mechanisms by which DBD plasma actuators influence flow characteristics, and are thus able to control that flow, depend strongly on their modes of actuation. Here two different modes based on steady and unsteady actuation are compared and investigated. A simple sinusoidal voltage distribution and a duty cycled sinusoidal voltage were considered for these purposes. Leading edge separation around a stalled NACA 0012 airfoil at Re=3 ×10^16 is considered as test case. A simplified phenomenological model which uses the correct scale of the plasma body force is considered for the modeling of the plasma actuator effects. The steady actuation results show that flow control can be effectively achieved by this mode of operation with continuous injection of momentum in the boundary layer. Unsteady actuation with an imposed frequency equal to the calculated natural frequencies of the flow gives rise to a resonance actuation effect.info:eu-repo/semantics/publishedVersio

Substrate specificity and the effect of calcium on Trypanosomabrucei metacaspase 2

Metacaspases are cysteine peptidases found only in yeast, plants and lower eukaryotes, including the protozoa. To investigate the extended substrate specificity and effects of Ca<sup>2+</sup> on the activation of these enzymes, detailed kinetic, biochemical and structural analyses were carried out on metacaspase 2 from Trypanosoma brucei (TbMCA2). These results reveal that TbMCA2 has an unambiguous preference for basic amino acids at the P<sub>1</sub> position of peptide substrates and that this is most probably a result of hydrogen bonding from the P<sub>1</sub> residue to Asp95 and Asp211 in TbMCA2. In addition, TbMCA2 also has a preference for charged residues at the P<sub>2</sub> and P<sub>3</sub>positions and for small residues at the prime side of a peptide substrate. Studies into the effects of Ca<sup>2+</sup> on the enzyme revealed the presence of two Ca<sup>2+</sup> binding sites and a reversible structural modification of the enzyme upon Ca<sup>2+</sup> binding. In addition, the concentration of Ca<sup>2+</sup> used for activation of TbMCA2 was found to produce a differential effect on the activity of TbMCA2, but only when a series of peptides that differed in P<sub>2</sub> were examined, suggesting that Ca<sup>2+</sup>activation of TbMCA2 has a structural effect on the enzyme in the vicinity of the S2 binding pocket. Collectively, these data give new insights into the substrate specificity and Ca<sup>2+</sup> activation of TbMCA2. This provides important functional details and leads to a better understanding of metacaspases, which are known to play an important role in trypanosomes and make attractive drug targets due to their absence in humans

Resonant elastic and inelastic scattering. Astrophysical applications. New paradigm beyond drip-lines?

5 pages, 4 figures, Expérience GANIL/SPIRALInternational audienceTwo experimental techniques have been developed at GANIL using resonant elastic and inelastic scattering reactions in inverse kinematics. These techniques were used to study the structure of unstable nuclei. A brief description of the methods is presented through two examples of application in astrophysics. Moreover, new ideas and simple questions are put forward: what happens in the low energy tail of unbound nuclei ground state resonances

The mycorrhizal status of Phragmites australis in several polluted soils and sediments of an industrialised region of Northern Portugal

Roots of Phragmites australis from three polluted soils and sediments (a periodically flooded stream bank containing organic pollutants, a high-pH drying sedimentation pond and an acidic, periodically flooded sand polluted by industrial effluents) were sampled over a 1-year cycle of plant growth to assess the degree of colonisation by arbuscular mycorrhizal fungi (AMF). At the dry sedimentation pond, root samples of Juncus effusus and Salix atrocinerea were also taken to assess the presence of AMF throughout the year. Root colonisation was low (<5% root length colonised) but arbuscule presence peaked in P. australis during the spring and autumn prior to flowering. These changes in arbuscule abundance were also seen in a parallel greenhouse trial using seed taken from one of the sites. Roots of J. effusus contained mainly vesicular colonisation but arbuscule activity peaked during the winter months (December–March). S. atrocinerea roots were found to be ectomycorrhizal throughout the year but the fine feeder roots were colonised by AMF. The results confirm that semi-aquatics, like P. australis, can become arbuscular mycorrhizal but that this status changes during the year depending on soil moisture content and plant phenology. The influence of AMF in these polluted soils is uncertain but the potential exists to establish a more diverse plant ecosystem during the landscaping of these areas (phytostabilisation) by management of adapted plant and AMF ecotypes

Kinetics of the adsorption of bovine serum albumin contained in a model wine solution by non-swelling ion-exchange resins

Adsorption of wine proteins is an essential step in the production of white and rosé wines. In order to develop environmentally friendly adsorption processes, non-swelling adsorbents are required. The performance of selected non-swelling ion-exchange resins (Macro-Prep™ 50S and Streamline® SP) was studied by describing the process kinetics of the adsorption of BSA in a model wine solution. The process was assumed to be diffusion controlled and a shrinking core model was applied. Experiments were performed in the 5–35°C temperature range and with different equilibrium partition coefficients. The results obtained with the shrinking core model were theoretically consistent and the apparent diffusivity values correlated very well with theoretically estimated effective diffusivities combined with a linear dependence of porosity with temperature. Separating the temperature effect on porosity, the apparent diffusivity followed an Arrhenius type dependency with temperature with 16.9 kJ/mole activation energy

Noise-robust method for image segmentation

Segmentation of noisy images is one of the most challenging problems in image analysis and any improvement of segmentation methods can highly influence the performance of many image processing applications. In automated image segmentation, the fuzzy c-means (FCM) clustering has been widely used because of its ability to model uncertainty within the data, applicability to multi-modal data and fairly robust behaviour. However, the standard FCM algorithm does not consider any information about the spatial linage context and is highly sensitive to noise and other imaging artefacts. Considering above mentioned problems, we developed a new FCM-based approach for the noise-robust fuzzy clustering and we present it in this paper. In this new iterative algorithm we incorporated both spatial and feature space information into the similarity measure and the membership function. We considered that spatial information depends on the relative location and features of the neighbouring pixels. The performance of the proposed algorithm is tested on synthetic image with different noise levels and real images. Experimental quantitative and qualitative segmentation results show that our method efficiently preserves the homogeneity of the regions and is more robust to noise than other FCM-based methods