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This paper presents the analyses of the influence of different asphalt types on the mechanical properties of a dense asphalt mixture. Two penetration binders, CA 60/80 and CA 80/100, and styrene-butadiene-styrene (SBS) a modified polymer binder were used. Mechanical properties as cohesion, resilient modulus, indirect tensile resistance and rutting were evaluated. The results allow concluding that the mixture fabricated with polymer modified binder presents a better behaviour in the mechanical properties evaluated. Also, the compaction energy and test temperature have greater influence on the mechanical properties in mixtures fabricated with penetration binder than those done with polymer modified binder. [ABSTRACT FROM AUTHOR]

This paper presents a study on the stresses in a joint of three structural timber elements made with punched metal plates. The aim of the work was to determine the effect of significant variables, such as contact between pieces working in compression, thickness of the plate, load levels and the joint design. Parametric finite element models of the joint were developed. The analysis showed that there is a value of the gap between timber pieces over which the contact begins, and another value under which the percentage of contribution of the force transmission by contact keeps constant. These values are independent of the thickness of the plate or the joint design. [ABSTRACT FROM AUTHOR]

In this paper, the differences between the equilibrium constants and conversions, for the dehydrogenation of paraffins, calculated by three methods and the values traditionally accepted in the literature are presented. Usually, it is accepted that the equilibrium conversions, for the dehydrogenation of paraffins, increase with the number of carbons in a monotonous way. However, the conversions calculated in this work for paraffins from C3 to C10, oscillate between 15 and 20%, and only from C11 a similar trend to the traditionally reported values is observed. The trend widely mentioned in the scientific literature shows important differences with the results obtained in this work, concluding that the accepted tendency between equilibrium conversion and number of carbons is not correct. [ABSTRACT FROM AUTHOR]

This paper presents the development of an amperometric composites inmunosensor based on a vegetable protein for the determination of anti-Ac S. mansoni. The inmunosensor consists of a rigid matrix built with graphite and epoxy resin in which immobilizes covalently the Apyrase. The strategy of immobilization is based in silanization of the matrix composites with 3-Aminopropyltriethoxysilane (3-APTES) and its activation by glutaraldehyde. The detection was monitored by cyclic voltammetry Fe(CN)6 4-/Fe(CN)6³, obtaining a response quasi-reversible of the immunosensor and very stable over time. The immobilization was also characterized by angles contacts and scanning electron microscopy. These qualities are useful for determination clinical of schistosomiasis given the speed of response and sensitivity. [ABSTRACT FROM AUTHOR]

In this paper calculations of the adsorption of nitrogen, methane and hydrogen on carbonaceous surfaces that have different curvatures are presented. The density functional theory (DFT) was used including a functional PW91PW91 along with a set of 6-31G basis (d, p). The results were adjusted to the potential of 12-6 Lennard-Jones to get the interaction parameters. The parameters of the 12-6 Lennard-Jones potential show no important dependency on the curvature of the nanotubes in the range considered in this study. [ABSTRACT FROM AUTHOR]

This paper presents a proposal for the teaching of welding processes that includes an applied pedagogical model, a development methodology and a guide for the preparation of classroom projects directed to students of Mechanical and Industrial Engineering, all under the concept of training by competency. A project developed in a company of the welding sector, directed to the control and quality of welded joints was done, using the proposed methodology. The application of the model significantly motivated the students in the learning of welding and related processes enhanced the relation with the industry, and generated important documents developed by students with advice of professors and professionals of the companies. [ABSTRACT FROM AUTHOR]

This paper presents a simulation of electricity production from several small wind turbines in the wind regime of Olinda-PE-Brazil, taking into account a number of records wind speeds and temperature in 1998, with the aim of developing a performance analysis tool that allows its selection. The hourly wind speed data were discretized at appropriate intervals to allow better handling of the information contained in the curves of electricity, supplied by manufacturers. The tool allows a comparative analysis of the performance of wind turbines, both in the aspect of the electrical energy production as its efficiency in function of wind speed. The results show that of the local wind regime influenced the production of electricity and that the data provided by manufacturers must be certified. [ABSTRACT FROM AUTHOR]

This paper describes an experimental study based on the norm DIN 66111 and centrifugal analysis of particle with diameters less than 200 nm. The hindrance function of sedimentation velocity presented by Richardson and Zaki (1954), in which the porosity of a suspension that depends on the draining regime of fluid over a particle is an exponential function, is used. For Reynolds numbers smaller than 0.25, the value of the exponent is constant and equal to 4.65. This value does no take into account the increment of the electro chemical forces and the diffusion effects acting on particles with non-colloidal sub-micron diameters. The results show that the hindrance function exponent for this type of system is different from that used by Richardson and Zaki. [ABSTRACT FROM AUTHOR]

In this paper, viscoelastic liquids spray emission generated by vibration and the influence of their physical properties are studied. The fluid contained in a cell is subjected to a field of periodic vertical forces, for which the excitation amplitude and frequency are controlled. Different mixtures of kerosene with viscoelastic polymer were used and results were modelled using equations applicable to Newtonian fluids with acceptable results within the values of the operating conditions considered. Also, the dependence of drop size with the quantity of polymer added, the acceleration and the frequency applied was determined. It is concluded that Newtonian fluids models can be applied to liquids with characteristics similar to those studied in this work. [ABSTRACT FROM AUTHOR]

This paper presents a study on the effects of some variables on the adsorption process of heavy metal ions in polluted wastewaters. The effects of pH, ion concentration, biomass concentration and pre-treatment of the biomass on the biosorption process of Pb2+, Cd2+ y Cr3+ in artificial solutions using non-living Saccharomyces cerevisiae were evaluated. It was observed that pH, biomass concentration and biomass pretreatment had a significant effect on the biosorption of Pb2+. For the adsorption of Cr3+ the only important factors were pH and concentration biomass, while for Cd2+ biosorption the effects of biomass concentration, pH and the presence of co-ions in the solution were significant. [ABSTRACT FROM AUTHOR]

This paper presents an integral study on the quality of the superficial waters in ponds and streams of the watershed of Amajac river. The problems associated to specific pollutants are identified and alternative solutions are detailed to be used in public policies of water resources. Four ponds, one lake and five streams were considered in the study and runoff volume, water speed, and maximum depth were measured. Also, the main physical, chemical and biological parameters were determined: dissolved oxygen, fecal coli forms, nitrogen, phosphorus, sulphate, carbonate, bicarbonate, chloride, and manganese. According to the results, it is concluded that water of the river in Tulancingo city is strongly contaminated. [ABSTRACT FROM AUTHOR]

This paper studies the effect of the mass percentage of the catalyst and the molar ratio oil:alcohol for different alcohol-catalyst systems, in the optimization of alkyl esters production from crude palm oil. Factorial design 32 and response surface methodology were used and quadratic polynomial equations by a multiple regression analysis were obtained. The evaluated answer was the percentage of conversion to glycerine using the norm of the American Oil Chemists' Society, AOCS Ca 14-56. The two variables significantly affect the conversion and the molar ratio effect is larger than the effect of the amount of catalyst. Optimum conditions vary for each system, but in general for the homogeneous catalysts the mass percentage of the catalyst is smaller (1 to 2%) than for heterogeneous (5 to 6%) and large molar ratio are required (1:12-1:40). The properties of fuel obtained are according to American standard requirements for biodiesel. [ABSTRACT FROM AUTHOR]

In this work the phenomenon of hydration is studied in recycled fiber. As raw material kraft of the first cycle (sample A) is used and results compared with recycled kraft fiber of the n cycle (sample B). Both fibers are separately treated under hydration conditions. Later, fibers A and B are mixed, 50 % each, generating a fibrous mixture to manufacture a new paper sheet. As response factors the following were evaluated: tensile resistance, elongation, tensile absorption energy and water retention value (gwater/gfiber). The hydration is carried out with: water, sodium hydroxide and two surface active agents with moisture activity. In water the mixture of fibbers reaches its maximum capacity of water absorption (1,2 gwater/gfiber) in 18 h, in alkaline solution (1,4 gwater/gfiber) and in surface active agent (1,3 gwater/gfiber) in 1 h. [ABSTRACT FROM AUTHOR]

This paper presents the state of the art of methods for studying voltage stability in power systems. Description and chronological classification of each technique for detection and prediction of voltage stability, since the identification of the problem in the 60's, are done. Also, modifications to the original techniques and their utilization to solve common problems of voltage-stability in the power system are presented. Comparisons of the different techniques were done according to literature information and the advantages and disadvantages of each technique in the solution of voltage stability problems are discussed. [ABSTRACT FROM AUTHOR]

This paper studies the multicomponent azeotropic capacity prediction of activity coefficient models. Wilson and UNIFAC models are used for homogeneous azeotropes while UNIQUAC and UNIFAC models are used for heterogeneous azeotropes. Calculations were done with the commercial software DISTIL and HYSYS using the DISTIL Data Base for the binary parameters. In the case that binary parameters were not available they were estimated from binary experimental data. The prediction capability of the models decreases as the number of components in the mixtures increases. Prediction from Wilson and UNIQUAC are good for ternaries and poor for 4 and 5 component mixtures. Prediction using UNIFAC is as good as those from Wilson and UNIQUAC. However, calculations with UNIFAC produce occasionally two liquid phases in homogeneous systems. [ABSTRACT FROM AUTHOR]

This paper analyzes the use of the oscillation-based test (OBT) to test high-order continuous-time ladder filters. The OBT implementation requires converting the filter under test into a non-linear oscillator. The prediction of the oscillation parameters (frequency and amplitude) is done using a combination of analytical and graphical methods, resulting very appropriate for the filters under study (fifth-order elliptic and Butterworth, RC active type). For characterizing the OBT scheme, a single deviation fault model for the filter passive components was adopted, and the lowest deviations in the value of the components, capable of being detected by monitoring amplitude and frequency, were established. The fault simulation results show that OBT is very appropriate for detecting faults in the Butterworth filter. For the elliptic filter, good results were observed if the hard-to-test faults are related to the filter behavior. [ABSTRACT FROM AUTHOR]

This work presents a thermodynamic analysis of a cogeneration energy process with black liquor gasification obtained in pulp and paper industries, using exergy balances to identify and quantify the main irreversibilities in the process. The cogeneration process was analyzed using a commercial simulator from which it was possible to develop the exergy balance. The influence of the composition of the gases produced in the gasifier over the exergy losses in the process was evaluated. The most appropriated operating conditions in the gasifier to reduce the concentration of these components, which are responsible for the exergy losses are the low temperature (700 °C) and the low pressure (200 kPa). The analysis showed to be useful to determine the technical viability of this alternative process of energy generation using black liquor gasification. [ABSTRACT FROM AUTHOR]

This paper describes the design and installation of an automated experimental device applied to a parallel co-current hot air dryer to perform drying studies in the field of food engineering. The development of this work was divided into two main activities: (i) design of the automation system and (ii) validation of automatically collected data. A device capable of collecting and registering real time data and images from drying processes, and transmitting them through Internet was obtained. The data processed by the automatic device was statistically validated. It is concluded that the proposed automation device is feasible, reliable and attractive for the users, facilitating the teaching-learning process in an important area of Food Engineering. [ABSTRACT FROM AUTHOR]

This paper presents a software tool for the Information View of CIMOSA architecture (Computer Integrated Manufacturing Open System Architecture). The aim is to allow users to model the business information needs with a finite set of building blocks, completing the life cycle of models defined by CIMOSA. The METRIC methodology has been followed for the analysis, design, construction and implementation of the system. The results highlight the modeling of Information Elements and their associated characteristics. It is concluded that the tool promotes alignment between business and information system, avoiding redundancy and inconsistencies and provides flexibility for the information system. [ABSTRACT FROM AUTHOR]

The objective of this paper is to show the viability of using thermodynamics models of activity coefficients (Wilson, NRTL, UNIQUAC) programmed with matrixes, instead of being programmed with cycles. The vapor-liquid equilibrium relation of mixtures Methanol-Ethanol-Benzene and Acetone-Chloroform-Methanol, represented with residue curve maps and distillation lines maps, was calculated. To obtain better solutions and objectives conclusions, the study was been supported with statistical design of experiments. The matrix programming showed to be faster than the conventional cyclic model, independent of the activity coefficient model used. [ABSTRACT FROM AUTHOR]

This paper presents a method based on the corresponding states principle for predicting the density of a fluid given a minimum amount of information. The method is based on a molecular formulation of the principle of corresponding states, using methane as a reference fluid. The densities of the various natural gas mixtures were calculated at temperatures between 95 and 50 K and compared with experimental data and with predictions of two correlations and eight equations of state. The proposed corresponding states method is the most accurate and reliable correlation to predict saturated liquid densities, and gives deviations lower than 0.1% for natural gas and less than 0.2% for liquefied petroleum gas. [ABSTRACT FROM AUTHOR]

This paper presents the similitude found between flow sheets, material balances and equipments employed in the concentration of borates, to obtain base refined borates and to obtain high added value borates. Spread sheet calculations are used to determine the production costs for different operating conditions and to analyze the opportunity and convenience of changing the final product, using the same process plant. A study case is considered in which 10 tn/hr of ulexite concentrate or the same amount of hydroboracite are produced. The cost per ton of B2O3 was 94.3 US dollars for the concentrated ulexite and 67.5 US dollars for concentrated hydroboracite. It is concluded that the proposed method is an useful tool for the economic analysis of the productive process considered in this study. [ABSTRACT FROM AUTHOR]

This paper presents the application of an evolutionary algorithm using Matlab to obtain the optimum main angles of the cutting geometry of a machining tool. The optimization method considered the non linear model of Kaldor and Venuvinod. Different algorithm configurations were tested using data obtained from the literature. Several simulations were carried out to validate the performance of the algorithm and to show the usefulness of the method employed. It is concluded that that the proposed approach shows to be stable and coherent in the results for the cases studied. [ABSTRACT FROM AUTHOR]

This paper presents a review focused on the understanding of the concepts behind the term Thermoplastic Starch -TPS to facilitate the development of biodegradable products. The literature review covered in this work is grouped into six categories: sources, characteristics and uses of starches; fusion and mechanisms of transformation; plasticizing properties and verification process; chemical and biochemical changes; aging and biodegradation; and mixtures for the development of new materials. This categorization allows understanding the advances in this field over the past fifteen years, as well as major challenges for the future, being the most important reducing the sensitivity to moisture and retarding the retrogradation of the thermoplastic matrix. [ABSTRACT FROM AUTHOR]

To improve the quality of service in cell systems, techniques of Dynamic Assignment Channels are used to reduce the probability of blocking calls. In this paper an algorithm of assignment channels is required to reduce the probability of blocking, extending the system capacity to add new calls. This is obtained by using an interchange of channels of current calls and reducing the restrictions of electromagnetic compatibility. According to this, the algorithm has to provide solutions of commitments between two different objectives; on the one hand reduce the amount of assignments, and on the other to do the same with the level of interference due to the flexible restrictions of electromagnetic compatibility. A heuristic focus based on the evolution paradigm is presented to solve the multi-objective optimization problem. Two evolutionary multi-objective algorithms (SPEAII y NSGA II) are compared by the use of two different metrics. The results show that the proposed methodology can be applied to different generations of mobile communication systems. [ABSTRACT FROM AUTHOR]

A structured procedure, implemented in Excel®, to analyze the present situation in an enterprise with the purpose of evaluating the necessary conditions to implement an innovation process in the maintenance management system. The procedure allows obtaining a knowledge base of the company's technical system of the present maintenance management. The proposal is composed by an audit and an expert analysis based on rules that include aspects related to the management form, the technological level of the productive equipment, the degree of organizational maturity, the maintenance goals and the physical and financial requirements to implement the selected conceptions. This procedure allows identifying the weaknesses and strengths of the productive system and the maintenance to plan in optimum form the proposed innovation maintenance. [ABSTRACT FROM AUTHOR]