Spectral analysis of the biharmonic operator subject to Neumann boundary conditions on dumbbell domains

We consider the biharmonic operator subject to homogeneous boundary conditions of Neumann type on a planar dumbbell domain which consists of two disjoint domains connected by a thin channel. We analyse the spectral behaviour of the operator, characterizing the limit of the eigenvalues and of the eigenprojections as the thickness of the channel goes to zero. In applications to linear elasticity, the fourth order operator under consideration is related to the deformation of a free elastic plate, a part of which shrinks to a segment. In contrast to what happens with the classical second order case, it turns out that the limiting equation is here distorted by a strange factor depending on a parameter which plays the role of the Poisson coefficient of the represented plate.Comment: To appear in "Integral Equations and Operator Theory

KCS34 evaluation for WHR in cement industry

The simple Kalina cycle system 34 (KCS34)- has been studied to perform energy cogeneration from the waste heat recovery (WHR) in preheater cement industries. The preheater available energy was considered from a 5000 tc/day cement production capacity. Thermodynamic and simplified exergoeconomic models were developed in the Engineering Equation Solver (EES) software. Several cycle thermodynamic parameters as ammonia-water mixture concentration and turbine operating pressure were wide-ranging in order to maximize the cycle thermal efficiency aiming to minimize the electricity generation cost. The temperature-entropy KCS34schematics were shown for different best results aiming to understand which set of parameters targets the maximum KCS34performance. The produced power, the thermal cycle efficiency, the exergetic efficiency and the exergoeconomic electricity specific cost were plotted for the different ranges of the independent parameters. The optimum results for a range specific investment price were presented. The main conclusions indicate that in the range of the studied parameters the turbine operating pressure caused a generated power variation greater than the ammonia-water mixture concentration in the KCS34performance. It was also possible to conclude that the KCS34is competitive with the existing electricity prices. In this case the KC proved to be applicable for WHR in the cement industry

AN EXERGY COST ANALYSIS OF A COGENERATION PLANT

The exergy analysis, including the calculation of the unit exergetic cost of all flows of the cogeneration plant, was the main purpose of the thermoeconomic analysis of the STAG (STeam And Gas) combined cycle CHP (Combined Heat and Power) plant. The combined cycle cogeneration plant is composed of a GE10 gas turbine (11250 kW) coupled with a HRSG (Heat Recovery Steam Generator) and a condensing extraction steam turbine. The GateCycleTM Software was used for the modeling and simulation of the combined cycle CHP plant thermal scheme, and calculation of the thermodynamic properties of each flow (Mass Flow, Pressure, Temperature, Enthalpy). The entropy values for water and steam were obtained from the Steam Tab software while the entropy and exergy of the exhaust gases were calculated as instructed by. For the calculation of the unit exergetic cost was used the neguentropy and Structural Theory of Thermoeconomic. The GateCycleTM calculations results were exported to an Excel sheet to carry out the exergy analysis and the unit exergetic cost calculations with the thermoeconomic model that was created for matrix inversion solution. Several simulations were performed varying separately five important parameters: the Steam turbine exhaust pressure, the evaporator pinch point temperature, the steam turbine inlet temperature, Rankine cycle operating pressure and the stack gas temperature to determine their impact in the recovery cycle heat exchangers transfer area, power generation and unit exergetic cost

Minkowski's Footprint revisited. Planetary Nebula formation from a single sudden event?

M1-92 can be considered an archetype of bipolar pre-planetary nebulae. It shows a clear axial symmetry, along with the kinematics and momentum excess characteristic of this class of envelopes around post-AGB stars. By taking advantage of the new extended configuration of the IRAM Plateau de Bure interferometer, we wanted to study the morphology and velocity field of the molecular gas better in this nebula, particularly in its central part. We performed sub-arcsecond resolution interferometric observations of the J=2-1 rotational line 13CO M1-92. We found that the equatorial component is a thin flat disk, which expands radially with a velocity proportional to the distance to the center. The kinetic age of this equatorial flow is very similar to that of the two lobes. The small widths and velocity dispersion in the gas forming the lobe walls confirm that the acceleration responsible for the nebular shape could not last more than 100-120 yr. The present kinematics of the molecular gas can be explained as the result of a single brief acceleration event, after which the nebula reached an expansion velocity field with axial symmetry. In view of the similarity to other objects, we speculate on the possibility that the whole nebula was formed as a result of a magneto-rotational explosion in a common-envelope system.Comment: 4 pages (2 figures

FOPI/FOPID Tuning Rule Based on a Fractional Order Model for the Process

This paper deals with the design of a control system based on fractional order models and fractional order proportional-integral-derivative (FOPID) controllers and fractional-order proportional-integral (FOPI) controllers. The controller design takes into account the trade-off between robustness and performance as well as the trade-off between the load disturbance rejection and set-point tracking tasks. The fractional order process model is able to represent an extensive range of dynamics, including over-damped and oscillatory behaviors and this simplifies the process modelling. The tuning of the FOPID and FOPI controllers is achieved by using an optimization, as a first step, and in a second step, several fitting functions were used to capture the behavior of the optimal parameters of the controllers. In this way, a new set of tuning rules called FOMCoRoT (Fractional Order Model and Controllers Robust Tuning) is obtained for both FOPID and FOPI controllers. Simulation examples show the effectiveness of the proposed control strategy based on fractional calculus

Pertinencia de una secuencia didáctica que propenda por el desarrollo de competencias de lectura crítica de textos argumentativos

Maestría en EducaciónEn la actualidad los paradigmas de la educación han tomado un nuevo horizonte, en especial aquellos que apuntan al afianzamiento de las Competencias Lectoras, las cuales son el pilar del aprendizaje en la Educación Universitaria ya que permiten al estudiante mantenerse actualizado. Por ello, este proyecto de investigación buscó “Determinar la pertinencia de una secuencia didáctica centrada en el uso de niveles de lectura minuciosa que propenda por el desarrollo de competencias asociadas a la lectura crítica de textos argumentativos”. Para esto, se aplicó una propuesta con un diseño cuantitativo fundamentado en los principios positivistas, con un alcance descriptivo, que tuvo un diseño cuasiexperimental en donde se seleccionó una muestra no probabilística en dos grupos; uno llamado grupo experimental y el otro, grupo control. Esta investigación tomó como columna teórica los planteamientos de Paul (2003), Solé (1994) y Cassany (2006) en cuanto a las definiciones sobre lectura; a Camps (2004) y Zayas (2006) para definir SD; a Niño (2007) y Diaz (1996) para referirse a texto argumentativo y finalmente a Ospino y Samper (2014), Duran, Jaraba y Garrido (2007) en cuanto a competencia comunicativa. La puesta en marcha de la propuesta resulto satisfactoria al comparar la prueba inicial y la prueba final, ya que luego de la implementación de la SD y al evaluar nuevamente a los estudiantes se encontró que mejoraron en lo concerniente al uso de estrategias metacognitivas, comprensión integral de un texto, desarrollo de ideas e interés por aproximarse a procesos de lectura y escritura más avanzados.At present the paradigms of education have taken a new horizon, especially those that aim to strengthen the Reading Competences, which are the pillar of learning in University Education since they allow the student to keep up to date. Therefore, this research project sought to "Determine the relevance of a didactic sequence focused on the use of levels of careful reading that encourages the development of skills associated with the critical reading of argumentative texts." For this, a proposal was applied with a quantitative design based on positivist principles, with a descriptive scope, which had a quasi-experimental design in which a non-probabilistic sample was selected in two groups; one called experimental group and the other, control group. This research took as a theoretical column the approaches of Paul (2003), Solé (1994) and Cassany (2006) regarding the definitions about reading; a Camps (2004) and Zayas (2006) to define SD; a Niño (2007) and Diaz (1996) to refer to argumentative text and finally to Ospino and Samper (2014), Duran, Jaraba and Garrido (2007) regarding communicative competence. The implementation of the proposal was satisfactory when comparing the initial test and the final test, since after the implementation of the SD and when evaluating the students again it was found that they improved with regard to the use of metacognitive strategies, comprehensive comprehension of a text, development of ideas and interest in approaching more advanced reading and writing processes

Non-Invasive measurer for methane and carbone dioxide emissions in bovine cattle through TRIZ

Greenhouse gases (GHG), mainly methane (CH4) and carbon dioxide (CO2), can be generated in agricultural activities, not only in waste but also in the process of breathing of livestock. The Theory of Inventive Problem Solving (TRIZ) is an innovative Russian methodology that allows finding the solution to a problem raised. This paper presents the use of two TRIZ tools to design a non-invasive prototype that detects CH4 and CO2 emitted by cattle in real time. The tools were the matrix of technical contradictions and the nine-screen analysis with which the parameter to be improved (A) was found and the best possible solution to design a prototype that allows quantifying gases for animal welfare, Final Ideal Result (IFR) a wireless module with a sensor system for each of the gases placed on the bovine head, which convert the detected gas into an electrical signal to be sent wirelessly to a range of 1.5 km in free space at a receiver for its visualization representing the parts per million (ppm) of CH4 and CO2 that the bovine is generating during the measurement

Study of Different Aging Conditions for Analysis of Microstructure and Mechanical Properties of F357 Alloy Fabricated in LPBF Printer

Aluminum F357 is a widely used material for casting in aerospace and additive manufacturing industry. Heat treatments are commonly applied to some aluminum alloys to modify its properties. With a further study on the aging and performance of the F357 with 3D printing technology, several industries benefit of this, military, automotive and aerospace are some examples, because the numerous components casted in service. This work presents mechanical properties of F357 specimens fabricated with EOS technology and subjected to heat treatments. Heat treatments conditions were applied to tensile specimens and tested. Furthermore, the specimens were subjected to artificial thermal aging for 100 h and 1000 h at two different temperatures (285 ºF and 350 ºF), and their mechanical properties were also determined. Finally, remarks on the comparison between the heat treatments and the effect of thermal aging on the microstructures and mechanical properties of the specimens will be presented.Mechanical Engineerin