Munoz M.,University of Zaragoza |
Moreno F.,University of Zaragoza |
Monne C.,University of Zaragoza |
Morea J.,University of Zaragoza |
Terradillos J.,Centro Tecnologico
Renewable Energy | Year: 2011
In this work, biodiesel from waste vegetable oil was used as an additive in low sulphur diesel fuel in automobile engines. The result was a fuel mixture with high lubricating power. According to the lubrication trials, the experimental mixtures complied with lubricity conditions established by European regulations, even when only a small quantity of biodiesel was used. It was also found that the mixtures were compatible with different engine gaskets and engine lubricant. Lastly, bench tests were performed using an automobile engine with mixtures of diesel fuel without conventional lubricant additive and biodiesel. The results showed that engine performance curves were very similar to those obtained with diesel fuel and that contaminating emissions from the engine decreased substantially by including biodiesel in the fuel, except for nitrogen oxides. © 2011 Elsevier Ltd.
Da Silva Jr. W.M.,Centro Tecnologico |
De Mello J.D.B.,Laboratorio Of Tribologia E Materiais
Proceedings - International Brazilian Conference on Tribology | Year: 2010
Recent studies state that the wear mechanisms of material removal are connected to the movement of the active particles present at the wear interface. According to tribological conditions, active wear particles slide or roll between surfaces. Particles rolling result in multiple indentations on wear surface. This work presents four experimental methods to evaluate the effect of indentations superimposition in the prevailing wear mechanism. A new device was especially developed to reproduce the abrasive particle interaction. In order to study the effect of superimposition on wear mechanism, series of indentations were created on M2 tool steel sample surfaces by varying the distance between indentations. Analyses were carried out using laser interferometry and SEM. Only one of the methods described in this work presented consistent results that permit the identification of the superimposition degree range, in which wear was observed. Tests showed that a small degree of superimposition results in plastic deformations of the surface. Degrees of superimposition of indentations higher than 50% resulted in mass loss. This method also allows the mapping of the average depth of indentations in function of superimposition degree and normal load of interactions.
Barcelos M.V.,Federal University of Espirito Santo |
Vieira E.A.,Federal University of Espirito Santo |
de Oliveira N.J.L.,Centro Tecnologico |
Machado M.L.P.,Federal University of Espirito Santo
Revista Escola de Minas | Year: 2013
The softening behavior changes that occur during hot deformation of steel is directly related to processing parameters such as strain, strain rate, temperature, interpass time and cooling rate. A structural steel was analyzed by hot rolling simulation using hot torsion tests. The specimens were machined from work piece after roughing mill. Isothermal torsion and multiple strains in continuous cooling torsion tests were performed in hot deformation laboratory of CETEC, in Belo Horizonte-MG. Peak stress and strain for temperatures ranging from 1150°C to 650°C were determined through flow curves generated by isothermal torsion tests and metallographic analysis were performed to verify the behavior of grain size of the material. The critical temperatures (Tnr and Ar3) were calculated by equations available in literature and compared to values obtained from the test flow curves (the variation did not exceed 1.8%).
Albano C.,Venezuelan Institute for Scientific Research |
Albano C.,Central University of Venezuela |
Perera R.,Simon Bolivar University of Venezuela |
Catano L.,Venezuelan Institute for Scientific Research |
And 3 more authors.
Polymer - Plastics Technology and Engineering | Year: 2010
The objective of the present work is to evaluate the compatibilization of composites of polyolefins (high-density polyethylene and polypropylene) with 30 wt.% hydroxyapatite of nanoscale particle size, employing grafted polymers to improve the interaction between phases and hence, the composite's properties. The functionalization of a high-density polyethylene and a polypropylene was performed in solution, employing acrylic acid as the grafting monomer and dicumyl peroxide as the initiator. The grafting degree was determined through volumetric titration. The nanoscale hydroxyapatite was synthesized through a precipitation method using calcium hydroxide and ammonium phosphate. Polyolefin composites were melt-blended in an internal mixer, varying the amount of compatibilizing agent at 4, 6, 8, and 10 phr. The grafting degrees obtained were 0.72 and 0.38 wt% for the high-density polyethylene and polypropylene, respectively. On the other hand, the melt flow rate values of the composites slightly decreased as the grafted polymer contents increased. The crystallinity degree also decreased in the presence of grafted polymers. The incorporation of the compatibilizing agent favored the dispersion and distribution of the hydroxyapatite particles. The Young's modulus and the tensile stress slightly increased in all composites. The values of activation energy decreased with the addition of the grafted polymers, which is attributed to the less thermally stable functionalized polymer, which is prone to thermal degradation at relatively lower temperatures due to the presence of a large content of carboxylic groups. Nonetheless, the activation energy increased with the amount of functionalized polymer incorporated into the composites due to the interaction between components at the polymer/filler interface. © Taylor & Francis Group, LLC.
Perez C.,Centro Tecnologico |
Palau A.,Obtuolor S.L
Tecnologia del Agua | Year: 2010
The odor contamination has been acquiring throughout the last years relevanee due to diverse factors. What was previously considered, as annoyance has become nowadays, a serious problem in some cases. Population's helplessness due to a legislation deficiency, in many cases, causes that the true importance of this type of contamination is not reflected. This article wants to come near to the problematic due to the scents through the sewer system. Usually it is common, to attribute to the scents to certain industries or activities without repairing that, sometimes, the root of the problem is underneath the surface.
Fernandez Villan A.,Centro Tecnologico |
Carus Candas J.L.,Centro Tecnologico |
Usamentiaga Fernandez R.,University of Oviedo |
Casado Tejedor R.,Treelogic Centro Tecnologico
IEEE Latin America Transactions | Year: 2016
According to estimates by the World Health Organization, about 285 million people suffer from some kind of visual disability, of whom 39 million are blind, resulting in 0.7% of the world population. Computer vision techniques and image analysis can help improve visually-impaired people. In this project, a system that allows for facial recognition and detection of spoofing adapted to the needs of disabled people is proposed, implemented and validated. The architecture has been carefully selected and subsequently implemented following an innovative facial normalization algorithm in order to increase both the recognition rate of facial identification and spoofing detection. The information provided to the user is composed by the name of the person identified and whether it is real or fake image (photograph). This information is provided by means of a text-tospeech tool. This architecture can be integrated into video doorphone installations (videointercom installations), devices with reduced computing capabilities or the users mobile phones. The architecture has been validated in a real environment with both real users and printed images achieving very good results. © 2016 IEEE.
Rossi F.,University of Coimbra |
Olabarria C.,University of Vigo |
Incera M.,Centro Tecnologico |
Garrido J.,University of Vigo
Journal of Sea Research | Year: 2010
Native and exotic seaweeds frequently lie on the beach and sustain part of the benthic food web. However, the role of exotic seaweeds as food sources for beach consumers has been poorly studied. We studied the temporal and spatial variability in the trophic significance of the invasive brown seaweed Sargassum muticum on sandy beaches. We measured the stable isotopes (δ13C and δ15N) in the tissues of S. muticum and of invertebrate consumers and estimated the dietary biomass proportion of S. muticum during four sampling dates at two beaches and heights on the shore. Samples were collected from eight pitfall traps placed at a distance of 2 m from each other. Detrital macroalgae and seagrasses were also collected by hand within an area of 30 cm around each pitfall trap. We measured the spatial and temporal variability in the isotope composition of the beach consumers and of S. muticum using different models of analyses of variance. We then calculated the biomass proportion of S. muticum to the animal diet with a two-isotopic mixing model. The invasive alga S. muticum seemed to be one of the main food sources for the amphipod Talitrus saltator and, to a less extent, for the isopod Tylos europaeus. The importance of S. muticum was however temporally variable and decreased during spring (in March and May), probably due to the availability of native macrophytes. The supply of invasive wrack to beach food webs thus deserves more attention if we want to understand their role in influencing food web dynamics. © 2009 Elsevier B.V. All rights reserved.
Carcel J.A.,Polytechnic University of Valencia |
Nogueira R.I.,Embrapa Agroindustria de Alimentos |
Rossello C.,University of the Balearic Islands |
Mariano E.S.,Polytechnic University of Valencia |
And 2 more authors.
Defect and Diffusion Forum | Year: 2010
Naik model, high intensity ultrasound, mass transfer, bioactive compounds, The olive crop has a great importance in the economy of Spain. Every year during the pruning of the olive trees a significant quantity of leaves are cut and discarded. It is known that these leaves constitute a source of antioxidant compounds and its processing would provide an added value to this raw material. Antioxidant compounds may be damaged when drying, the previous process to extraction. Thus, the goal of this work was to study the influence of the high intensity ultrasound applied during the drying of olive leaves on the kinetic of extraction of antioxidants compounds. From the parameters identified from Naik model, it can be concluded that the application of high intensity ultrasound during drying reduced the antioxidant activity of extracts at the equilibrium but increased the initial extraction kinetic compared to conventional hot air drying. This last aspect could have high interest to the antioxidant extraction from an industrial scale point of view. © (2010) Trans Tech Publications.
Parucker M.L.,Centro Tecnologico |
Klein A.N.,Centro Tecnologico |
Binder R.,Centro Tecnologico
Revista Materia | Year: 2014
The powder injection molding is a manufacturing process that allows high productivity to obtain complex geometry components, dimensional accuracy and good mechanical properties. In this process, a mixture of a quantity of powders and organic binders (polymers, waxes, oils) is obtained through injection of a mass (feedstock) which has rheological properties suitable for promoting the injection of this mass in a cavity of a mold. The production of nickel alloy by this process is an alternative to production of products that require advanced applications, which require resistance to corrosion and oxidation, mechanical strength at high temperatures and low coefficient of friction. This paper we present the study of the microstructural and mechanical properties of a nickel alloy (Ni-Fe-Cr-P) processed by powder injection molding, using carbonyl nickel powders with and without the presence of liquid phase during sintering. The results are compared with the alloy processed by powder compaction. The results demonstrate the need for increased amount of organic matter for developing the injection mass (feedstock: 15 wt.% polymer) for the types of metallic powders used (nickel INCO type 123 carbonyl) compared to commercial alloy feedstock typically use a smaller amount of organic matter (feedstock: 9 wt.% polymer). The largest quantity of organic matter needed for the preparation of the feedstock due to the morphology of the powders used (spiky) which promoted carbon retention during the extraction process, resulting in the need to optimize the extraction cycle and thermal sintering. Slower cycles and low temperature promoted the complete extraction of the ligands. The Ni-Fe-Cr-P alloy injected showed shrinkage of approximately 50%, and high levels of pores as compared to the compacted material, which influenced the mechanical properties and apparent hardness of the material. © 2014, Universidade Federal do Rio de Janeiro. All rights reserved.
PubMed | Centro Tecnologico
Type: | Journal: Studies in health technology and informatics | Year: 2012
There are various techniques available to measure human physical activity (PA). Accelerometer based techniques claim to be non-invasive and easy to use. The signal magnitude area (SMA) is the most extended feature used to measure the physical activity. It is calculated by sampling and filtering an accelerometer signal of at least at 50 Hz. SMA has a proven and widely accepted linear relation with the energy expenditure. A novel magnitude called JIM, which is more efficient than SMA, is proposed in this paper. The jerk-based inactivity magnitude (JIM) is also calculated from the acceleration signal, but at a sampling rate of 1Hz, increasing the battery life of the measuring system. This magnitude gives the same information as the SMA (correlation of 95%) and is validated with a group of 39 users in free-living conditions for at least 24 hours.