bluuebunny/crossref_metadata_2025 huggingface dataset:
INFLUENCE OF DEEP CRYOGENIC TREATMENT AT ABRASIVE WEAR RESISTANCE IN ASTM 743 CA6NM
Authors: Hernandez A. F. , Silva C. R. M. , Araujo J. A. , De Mello J. D. B.
Published: November 2018

The Deep Cryogenic Treatment (DCT) has been used for improvement of steel mechanical properties, basically the abrasive wear resistance. At this work the cryogenic treatment at -190oC for 20 hours was applied, after conventional heat treatment, to improve its abrasive wear resistance. The specimens, divided in two groups, had been austenitized for forty five minutes at 965oC and 1065oC, respectively, then quenched in oil at room temperature. Afterwards they were tempered at 565oC for 90 minutes, and then cooled in air. Subsequently some samples were treated cryogenically, and some of them were submitted to a new cycle of tempering at 565oC for 90 minutes. The performed experiment included: hardness brinell, Xraydifratometry, metallography and micro-abrasive wear test. Variations in the microstructure with an improvement in the abrasive wear coefficient were found. These variations are probably a positive effect of the DCT on the samples microstructure. The microstructure were transformed from blocks of parallel lath martensite to small parallel or almost parallel packages of fine needles forming austenite. Traces of previous or retained austenite were found delimiting the grains. It is presumed that micro-carbide homogeneously distributed in the matrix and in the grain´s contours of the retained austenite was formed.
AN EXPERIMENTAL STUDY OF THE CONVECTIVE HEAT TRANSFER ENHANCEMENT: APPLICATION OF TURBULENCE PROMOTERS
Authors: Zdanski P. S. B. , Bublitz A. E. , Correa C. N.
Published: November 2018

This work presents an experimental study addressing the effects of turbulence promoters on heat transfer rate at circular cylinder in external cross flow. Within this framework, the work focuses on assessing the effects of three kind of turbulence promoters (with circular, square and hexagonal cross sections) on convective heat transfer enhancement. The distance from turbulence promoters to the circular cylinder (50, 100 and 150mm upstream), as well as the free stream velocity inside the wind tunnel (Reynolds number) were the parameters investigated. The validation of the experimental methodology was performed by comparing the present results with empiric correlations available in the literature. The main results indicate that the convective heat transfer coefficient was enhanced when using turbulence promoters. The highest heat transfer enhancement obtained was around 25% correponding to the case of square turbulence promoter placed closely (50mm) to the circular cylinder. Finally, it is worth mentioning that all the experimental results for the convective coefficient were condensed in a new empirical correlation with good accuracy.
EVALUATION OF THE EFFECTS OF ILLUMINATION, TEMPERATURE AND PAINTING FINISH IN PSP TECHNIQUE
Authors: Costa R. S. , Avelar A. C. , Falcao Filho J. B. P.
Published: November 2018

This paper reports the results of global pressure measurements on a NACA0012 profile, obtained with the Pressure Sensitive Paint technique (PSP), and compares them with conventional pressure tap measurements with the purpose of analyzing the influence of parameters as illumination efficiency and temperature variation of the air flow in the accuracy of the PSP experimental results. The experimental measurements were conducted in the Pilot Transonic Wind Tunnel (TTP) of the Instituto de Aeronáutica e Espaço (IAE) for Mach number values of 0.4, 0.6 and 0.8. The experiments showed that in a carefully prepared experiment, under appropriated operational conditions, and rigorous adjustments of the PSP components, the obtained results can be accurate. Moreover, even when the influence of temperature is significant and the illumination condition is not ideal, it was possible to estimate well the impact caused in the pressure distribution over the model surface.
ANALISYS OF THERMAL EFFICIENCY OF A MODIFIED SOLAR COLLECTOR TYPE EVACUATED TUBE
Authors: Avallone E. , Sato A. I. , Scalon V. L. , Padilha A.
Published: November 2018

The need of renewable energy sources due to climate change and thus the search for clean energy sources, justify the growing investment on new types of solar collectors. The research has contributed to this expansion in the scope of solar concentrator collectors, with the efficiency as the main goal. Many works have been developed in order to optimize the thermal stratification of the fluid inside the tubes and heat reservoirs, as well as mathematical modeling considering the problem as transient heat flow as boundary condition. In this work is studied experimentally, the heating of the water by solar collector modified from the conventional evacuated tube, focusing on efficiency. With the help of CFD software, a theoretical analysis is done to visualize the phenomenon, assuming the same boundary conditions and geometric experimental problem. An important approach concerns the physical separation of the flows of both cold and hot water inside the evacuated tube. The system performance was analyzed using experimental tests performed outdoors with sunlight.
ENHANCEMENT OF THE CONVECTIVE COOLING OF TWO HEATERS IN A RECTANGULAR DUCT BY IMPINGING JETS
Authors: Marchi Neto I. , Altemani C. A. C.
Published: November 2018

A numerical investigation was performed to compare two alternative configurations for the convective air cooling of two heaters flush mounted on the lower horizontal wall of a rectangular duct. One configuration consisted of duct flow with uniform airflow velocity and temperature at the duct inlet and the heaters were located in the flow entrance region. In the other, the cooling was obtained by impinging air jets exiting with uniform velocity and temperature from two square holes on the upper duct wall just above the heaters. The simulations were performed under steady state conditions considering the three dimensional flow region of each configuration, where the conservation equations were solved. The results were presented in the form of the adiabatic Nusselt number and a dimensionless pressure drop for both configurations, in the range of the duct Reynolds number from 500 to 9,000.
A NOTE ON THE CONSTANT THERMAL CONDUCTIVITY HYPOTHESIS AND ITS CONSEQUENCE FOR CONDUCTION HEAT TRANSFER PROBLEMS
Authors: Gama R. M. S.
Published: November 2018

This work discuss the usual constant conductivity assumption and its consequences when a given material presents a strong dependence between the temperature and the thermal conductivity. The discussion is carried out considering a sphere of silicon with a given heat generation concentrated in a vicinity of its centre, giving rise to high temperature gradients. This particular case is enough to show that the constant thermal conductivity hypothesis may give rise to very large errors and must be avoided. In order to surpass the mathematical complexity, the Kirchhoff transformation is used for constructing the solution of the problem. In addition, an equation correlating thermal conductivity and the temperature is proposed.
DETERMINATION OF OPTIMAL ALGAE CONCENTRATION FOR CONTINUOUS GROWTH OF Scenedesmus sp. IN CHU AND MODIFIED CHU MEDIA
Authors: Santos K. R. , Mariano A. B.
Published: November 2018

The high cost of production in the cultivation of microalgae in photobioreactors is a barrier to be overcome, therefore is necessary to search to reduce the cost of cultivation. The objectives of this work are to compare the growth of the microalgae Scenedesmus sp. being cultivated in CHU medium and in an alternative medium composed mainly of fertilizer and to establish guidelines for growth under continuous mode. The research approach consisted on growing the microalgae in Erlenmeyer type photobioreactors and producing thegrowth curves for both media. The comparisons between the two, were made based upon three parameters: dry biomass, absorbance, and total lipid quantity. The experiments were made in triplicates in order to quantify the uncertainty in the measurements. The comparison of the cultivation in both media suggest that the modification of the chemical nutrients by fertilizer did not produce significant changes in the number of cells, dry biomass and lipids. In spite of that, the modification resulted in 20% cost reduction in the growth medium. In this way, the substitution of conventional nutrients by fertilizers, constitute an interesting alternative for the production of biomass from microalgae leading to a cost reduction. The results are used to develop strategies for continuous growth.
STEADY STATE FIXED BED COMBUSTION OF WOOD PELLETS. A SIMPLE THEORETICAL MODEL
Authors: Pinho C. , Ferreira T. , Marques E. , Almeida D. , Pereira C. , Paiva J. M.
Published: November 2018

The combustion of biomass follows a sequence of several distinct phases which begin with drying, the subsequent pyrolysis with the release of volatile components that burn in gaseous phase and finally the combustion of carbonaceous resiue, the time consuming step. For small solid fuel boilers, as it is the case of pellet boilers for domestic heating, biomass particles are continuously burned in fixed bed boilers or heaters. In these appliances the furnace is a metallic basket into which fuel particles are thrown and burn. The combustion air is introduced through orifices drilled in this metallic basket although some lateral air entrances are also found. The gaseous flow is a piston flow, the particles fall under gravity on the upper bed surface and as they burn they slowly move downwards until their size is small enough to fall down through the air entrance orifices or are dragged by the upcoming combustion gas flow. So the gaseous current has an up flow movement while the solid particles move downwards. It is assumed that the bed is at uniform temperature and all the average properties of the gaseous flow are constant with the exception of the oxygen concentration that diminishes as the gas flow rises through the bed. The mathematical development of a simple model that allows the calculation of the steady state burning time of a biomass particle in fixed bed, the amount of energy released, the fixed bed size and its particle inventory, is hereby presented. The pedagogical interest of this model is pertinent because it presents, in a synthetic way, the relative importance of the combustion kinetic, the mass transfer mechanism and the reactor fluid dynamics, upon the lifetime of a biochar particle during its combustion process.
HIGH-ORDER FINITE DIFFERENCE METHOD APPLIED TO THE SOLUTION OF THE THREE-DIMENSIONAL HEAT TRANSFER EQUATION AND TO THE STUDY OF HEAT EXCHANGERS
Authors: Campos M. D. , Romão E. C.
Published: November 2018

Numerical experiments for four test problems are carried out to demonstrate the performance of the present method and to compare it with the others classical methods. The numerical solutions obtained are compared with the analytical solution as well as the results by other numerical schemes with emphasis on the application involving heat exchange in a rectangular channel. It can be easily seen that the proposed method is simple to implement and very efficient.
CONSTRUCTAL DESIGN OF A TUBULAR ARRAY SUBJECTED TO FORCED CONVECTION
Authors: Pedrotti V. A. , Souza J. A. , Dos Santos E. D. , Isoldi L. A.
Published: November 2018

In this work a tubular array (four tubes) subjected to a transverse forced flow is analyzed in terms of thermal performance. Taking into account that there are two main assembles usually used in heat exchanger equipment (aligned and staggered), and that there exist an uncountable number of possible assembles for an array of tubes, present work proposes to use the Constructal Theory to build an optimized assemble. The distance between tubes (p), and the region where tubes can be positioned are the geometric constraint of the problem. Four values for p were considered: p = 1.25D (tube diameter), p = 1.5D, p = 2D, p is free (no restriction). Fluid flow is considered bi-dimensional, incompressible and laminar with ReD = 10 and Pr = 0.71. Mass, momentum and energy equations were solved by the Finite Volume Method (FVM) using FLUENT software. Geometry creation and mesh generation were performed with GMSH software while VISIT software was used for the post processing. Results have shown that imposing no restriction to tube positioning do not necessarily lead to best system thermal performance. In this particular study, setting p = 2D has resulted in best thermal performance.
ENERGY ANALYSIS OF LIPID EXTRACTION OF Scenedesmus sp. PRODUCED IN PILOT SCALE
Authors: Schroeder L. , Scherer M. D. , Balmant W. , Mariano A. B. , Vargas J. V. C.
Published: November 2018

he production of biodiesel from lipids extracted from microalgae biomass is a promising approach to biofuels. However, this approach is still not commercialized because of the high costs of processes associated with, for example, time consumption and / or biomass drying with intense energy usage. However, it was not possible to show extraction methods among the lipids existing in the literature, which could be applied specifically to the extraction of lipids from the microalgae Scenedesmus sp. from the large-scale wet biomass, which is the current challenge faced by the Center for Research and Development of Sustainable Energy Auto (NPDEAS). Therefore, in this study, the possibility of avoiding the drying process, and extracting lipids directly from humid biomass, using the saponification method, was tested and compared with conventional Bligh and Dyer extraction (B & D). This study introduced the cultivation of microalgae Scenedesmus sp. compact tubular photobioreactors 12 m3 in area 10 m2 (8 x 5 x 2 m). The classical method of lipid extraction from microalgae - B & D - brings many pigments and polar lipids that exist in the biomass and the conversion rate was only 65-66%, whereas the recovery of fatty material in the wet biomass by the saponification method showed high conversion rate (90-95%). Therefore, the saponification process showed a high recovery of fatty acids that can be easily converted into biodiesel by esterification, and it was shown that the stage of drying the biomass can be removed without losing the fatty acids. In relation to the energy usage in the process, it was shown that drying the biomass for extraction of fatty acids uses more energy than that produced in the final product, biodiesel, showing that the removal of fatty acids of the wet biomass is of strategic importance to the viability of microalgae biodiesel.
REDUCED-SCALE STUDY OF LIQUID FUEL STORAGE TANK FIRE USING FIRE DYNAMICS SIMULATOR
Authors: Centeno F. R. , Rodrigues E. E. C.
Published: November 2018

Most of the accidents that occur in liquid fuel storage tank parks are caused by fire. This paper presents a numerical study using Large Eddy Simulation through Fire Dynamics Simulator (FDS) for the simulation of liquid fuel (ethanol) storage tanks at different scales (real-scale 1:1, and reduced- scales, 1:2, 1:4, 1:8). This paper proposes correlations for flame height, and temperature profile and radiative heat flux profile in the region adjacent to the tanks. Correlations have as inputs the diameters of the tanks in real- and reduced-scale, temperature profiles and radiative heat flux profiles for a reduced-scale tank simulation, and then provide as outputs flame height and temperature profiles and radiative heat flux profiles for the tank in real- scale. Percentage errors of the correlations found in this study are lower than 2.0% and 0.6% for the maximum radiative heat flux and maximum temperature, respectively.
COMPARISON OF FLOW PATTERNS IN THE RADIOCEPHALIC ARTERIOVENOUS FISTULA THROUG IN VITRO AND IN SILICO STUDY
Authors: Oliveira F. C. M. , Bessa K. L. , Moreira R. W. C.
Published: November 2018

The vascular accesses to hemodialysis patients usually are through arteriovenous fistula (AVF) or synthetic grafts. The analyses of recirculation zones, stagnation points, secondary flow and low and high shear stress are very important points to study for understand the hemodynamic local in arteriovenous fistula. In this work, it was analyzed through computational fluid dynamics the streamlines in AVF and it was compared with the literature results. The flow patterns were visualized under steady and unsteady condition with Reynolds number ranging from 100 up 600. The results obtained from CFD were very similar with the literature results. The flow becomes more chaotic when the Reynolds number increases. Vortex can be seen in anastomosis region, occupying all transversal section of the artery. Thus, the results obtained using CFD look like the results obtained experimentally.
TWO-STROKE ENGINE BEHAVIOR (SMALL CHAINSAW) OPERATING WITH NON-COMMERCIAL FUEL BLENDS AND DIVERSE LUBRICATION
Authors: L. da Silva R. , Vieira M. M. , De Brito Jr S. X.
Published: November 2018

The paper presents results for experimental tests in a two-stroke internal combustions engine operating on commercial fuel (gasoline and ethanol blends), with different proportions in mineral oil for lubrication purposes. Appropriate instrumentation was used to carry out the measurement of the quantities of interest, namely fuel consumption (g/s), angular velocity (rpm) and emissions (CO2 and NOx). The methodology was based on regulations from INMETRO (motor vehicles energy conversion efficiency) and ABNT (testing of internal combustion engines). Results obtained are analyzed and discussed for the fuel consumption versus angular velocity (g/s x rpm) for each combination fuel blend and lubricating oil (quantities). Main findings are that fuel consumption increases non linearly as angular velocity increases and as lubrication lowers, while emissions decreases as angular velocity increases. Lowest fuel consumption and emissions occurred, respectively, for A25/L1:25 and A25/L1:50 (commercial fuel and standard lubrication).
COMPUTER ANALYSIS OF THE GMAW AND GMAW-CW WELDING THERMAL CYCLES
Authors: Mendonça E. A. M. , Braga E. M. , Ferreira A. S. A. , Maciel R. R. , Cabral T. S. , Lopes J. T. B.
Published: November 2018

A novel process of welding GMAW-CW (Gas Metal Arc Welding-Cold Wire) had been developed with it resemblance to the GMAW (Gas Metal Arc Welding), the GMAW-CW has an additional wire fed into de weld pool, allowing better deposition rates, while maintaining weld characteristics. However, there is a more complex situation related to the HAZ (Heat Affected Zone) and weld geometry prediction than the GMAW conventional. The welding energy is a high metallurgical important parameter because together with the geometric characteristics of the gasket and the preheat level is decisive in thermal cycles imposed to the material, and therefore in the possible microstructural transformations and behavior of the joint. The behavior of representative curves of thermal cycling reflects important aspects regarding the conditions used in welding. Usually such factors as the type of process, use or non- pre or post- heating, heat input, multipass welding, are able to establish differences in the form of a heat cycle curve. In this work, it was applied the dual ellipsoidal model of heat input, adapted to the GMAW-CW and compared to the same model over the GMAW, using existing experimental data and predicting the HAZ dimensions in function of weld and welding parameters. The results found had less than 10% error from experimental data in a more refined version of the model, whereas the difficulties to predict cold wire addition influences were not trivial.
MODELING AND OPTMIZATION POWER REQUIREMENTS OF ACTIVE ACOUSTIC LOUVRES
Authors: Maciel M. A. , Zuffi G. A. , Duarte M. A. V.
Published: November 2018

The development of new technologies for ventilated facades is within the context of energy efficiency of buildings , including the compatibility of the dichotomy between natural ventilation and soundproofing in tropical countries . Given this perspective, this work proposes the application of techniques for active noise control in acoustic louvers . One limitation of the spread of technical active noise control in buildings is the energy inherent in the technique. Thus, the proposed system is based on the reduction of structural vibrations of the shutter blades by using piezoelectric actuators . The acoustic transmission loss and energy requirements for active shutters are investigated from numerical modeling . The results suggest their technical feasibility with superior soundproofing to 30 dB and power consumption less than 35 W. Thus , the active noise control using piezoelectric actuators is presented as a promising technology , aligning soundproofing with low energy consumption Type the text of the abstract here, Times New Roman, 9, lower case letters, justified paragraphs, 1.0 line spacing. The abstract should state the objectives, methodology and main conclusions in 200 to 300 words. No not divide into paragraphs.
SOLUTION OF MULTIPHASE HEAT CONDUCTION PROBLEMS VIA THE GENERALIZED INTEGRAL TRANSFORM TECHNIQUE WITH DOMAIN CHARACTERIZATION THROUGH THE INDICATOR FUNCTION
Authors: Machado H. A. , Leite N. G. C. , Nogueira E. , Korzenowisk H.
Published: November 2018

The Generalized Integral Transform Technique (GITT) has appeared in the literature as an alternative to conventional discrete numerical methods for partial differential equations in heat transfer and fluid flow. This method permits the automatic control of the error and is easy to program, since there is no need for a discretization. The method has being constantly improved, but there still a vast number of practical problems that has not being solved satisfactory. In several brands of engineering, the transport equations have to be solved for a combination of different phases or materials or inside irregular domains. In this case, the mathematical resource of the Indicator Function can be employed. This function is a representation of the phases or parts of the domain with the numbers 0 and 1 for each phase. According to the method, the Indicator Function is defined by Poisson’s equation, which is added to the system of the transport equations. An integral is done along the curve that defines the interface that will generate the source term in Poisson’ equation used to calculate the Indicator Function distribution. The solution of the system of equations is done using the common GITT approach. Then, an analytical expression for each transformed potential of the indicator function and the other variables are available. Once the transformed potentials are known, the Indicator Function can be analytically operated, and the interface can be represented by an analytical continuous function. In this work, the use of the GITT in conjunction with the Indicator Function is proposed. The methodology is described and some previous results are presented. GITT is applied to a two-dimensional heat conduction problem in a multiphase domain with an irregular geometry, inside a square domain. The methodology presented here can be extended to all brands of convection-diffusion problems already solved via GITT.
CFD ANALYSIS OF PULVERIZED COAL COMBUSTION IN A BLAST FURNACE TUYERE: COMPARISON BETWEEN WSGG AND GG MODELS FOR RADIATION MODELING
Authors: Da Silva C. V. , Weber G. , Centeno F. R. , França F. H. R.
Published: November 2018

Combustion processes are being employed for many years, and remains a major source of energy for industrial operations through the conversion of chemical energy in thermal energy, besides being usually accompanied by formation of pollutants. This work presents a numerical investigation using the software Ansys CFX to model the process of combustion of pulverized coal injected into a blast furnace for production of pig iron making a comparison between WSGG and GG spectral models for gas radiation aim to verify the influence on the radiation heat transfer and the temperature field. Since global coal reserves are being constantly reduced, new techniques using coal are being studied. Among some effective techniques, there is the injection of pulverized coal through a tuyere installed at the bottom of the blast furnace. Thus, among the objectives of this work is to obtain information about the pulverized coal burning process injected. Firstly, it will be employed a North American coal as a base case in order to better understand the involved phenomena. Simulations were made using the actual operating conditions of a blast furnace, which uses atmospheric air enriched with oxygen for burning the coal. The same boundary conditions and operation of other investigations were considered in order to validate the model developed for this work, and so that it can be applied in similar situations, either in assessments or in projects of coal injection systems and combustion in blast furnaces. The results include temperature and velocity fields, oxygen concentration, and the formation of CO and CO2 and they are in agreement with data from literature. Comparing the results of this study with the results obtained in the work (Gu et al., 2010) It observed a qualitative similarity between them and also quantitative. Furthermore, it was found that, in this case, modeling the absorption spectrum of the combustion gases resulting in changes in flame form, but did not significantly alter the magnitude of temperatures, since the walls of the equipment are considered adiabatic.
GEOMETRIC OPTIMIZATION OF “+”-SHAPED CAVITY USING CONSTRUCTAL THEORY
Authors: Avendaño P. A. , Souza J. A. , Adamatti D. F. , Santos E. D. dos
Published: November 2018

In this work it is applied the Constructal Theory for the study of the geometry of an “+”-shaped isothermal cavity inserted in a conductive solid body. Main goal is to minimize the maximum temperature in the solid. The total volume of the solid and the total volume of the cavity are kept fixed while the dimensions of the cavity geometry vary according to constraints and degrees of freedom defined by the Constructal Design. The solid body has internal heat generation and its external surfaces are insulated. Cavity walls are isothermal with constant temperature Tmin. Obtained results indicate that the optimal performance of “+”-shape cavity is 37.2% better that the optimal performance of “C”-shape cavity and 10.8% better than the “T”-shaped cavity for the same thermal conditions.
CONSTRUCTAL DESIGN APPLIED TO A FINNED CHANNEL UNDER FORCED CONVECTION FLOWS WITH DIFFERENT IMPOSED PRESSURE DROPS
Authors: Feijo B. C. , Teixeira F. B. , Pereira M. S. , Rocha L. A. O. , Goulart J. N. V. , Isoldi L. A. , Santos E. D.
Published: November 2018

This paper aims to numerically study the heat transfer in a two dimensional finned channel under laminar, incompressible and forced convective flow with adiabatic walls. The main purpose is to maximize the convection heat transfer by changing the fin’s dimensions by means of Constructal Design. Numerical computations are performed for different Bejan numbers ranging from 0.182 up to 18.2. For all simulations the Prandlt number is kept constant, Pr = 0.71. The fluid motion throughout the channel is caused by imposition of pressure difference between inlet/outlet surfaces. Concerning heat transfer, it is caused by the difference of temperature between the inlet stream of fluid and the heated fins placed at the channel surfaces. The first fin is positioned in the lower surface of the channel while the second one is placed in the upper one. The problem is submitted to three constraints, the channel area (H × L), area of two fins and occupancy areas for the fins. It is considered here that both fins have the same fraction area (ratio between the fins and occupancy areas) f = 0.2. The problem is submitted to three degrees of freedom: H/L (ratio between height and length of channel), H3/L3 and H4/L4 which represent the ratio between the height and length of the first and second fin, respectively. Here, the second fin remains unchanged, being its dimensions H4/L4 = 2.0, whereas the first one is free to modify its dimensions, H3/L3. The channel dimensions are also constant. The solutions are sought using the conservation equations of mass, momentum and energy being these ones discretized through the Finite Volume Method (FVM). Results showed the importance of Constructal Design application for thermal improvement of the problem. Thermal efficiency differences of 5 times where achieved when comparing the best and worst cases. Other important observation is concerned with the effect of ratio H3/L3 over heat transfer ratio (q) which varied significantly from a case where a pressure drop is imposed in the channel to other case where the driven force is caused by imposition of velocity field at the channel inlet.
PERFORMANCE CORRECTION FACTORS FOR VAPOR COMPRESSION REFRIGERATION AND HEAT PUMP SYSTEMS TESTED WITH UNCONTROLLED CONDENSER CONDITIONS
Authors: Nobre G. M. , Vasconccelos A. A. , Cárdenas Gómez A. O. , Bandarra Filho E. P. , Parise J. A.
Published: November 2018

A method for experimental data adjustment consisting of correction equations for the performance parameters of the refrigeration/heat pump vapor compression cycle, when operation conditions depart from those established in testing standards, is here presented. A basic thermodynamic model allowed for a methodology to be developed so as to correct vapor compression cycle performance to a desirable operating condition. Correction factor equations are proposed for refrigerant mass flow rate, compressor specific enthalpy gain and evaporator refrigeration effect, for situations when condensing pressure has not followed standards conditions or has not been properly controlled during experiments. The method was verified against experimental data from a vapor compression water-to-water heat pump with controlled condensing temperatures of 30oC, 40oC and 50oC. In spite of the purposely excessive correction, ±10oC, a relatively good smoothness, as well as a good agreement among all conversions, was obtained with the standardized points. The model was also applied to a refrigeration system running with water-SWCNT nanofluid (single walled carbon nanotube with water as the base fluid) as the secondary fluid. It contributed to a better discernment of the actual influence of the nanofluid in the system performance.
UM NOVO MÉTODO DE ANÁLISE VOCAL ATRAVÉS DA TERMOMETRIA DA FALA: ESPERANÇA DE DIAGNÓSTICO PRECOCE DE LESÕES DAS PREGAS VOCAIS ?
Authors: Gomes Guilherme F. , Filho Evaldo D. M. , Vargas José Viriato Coelho
Published: November 2018

A voz é um fenômeno complexo que exige diversas medidas para a descrição de suas características porque inúmeras grandezas físicas estão envolvidas na sua produção. Os vários equipamentos existentes para análise vocal medem: vibração das pregas vocais, fluxo aéreo glótico, volume do ar que passa através das pregas vocais, pressão subglótica, área de contato da mucosa das pregas vocais e sinal sonoro vocal. Após a entrevista do falante, observação e descrição de sua voz, dados obtidos do laboratório de voz devem ser integrados à análise vocal para proporcionar avaliação vocal completa. As medidas de análise vocal encaixam-se como pecas de um quebra-cabeças, cada qual levando a conexão natural da peça seguinte e, juntas, fornecem um quadro que não pode ser visualizado com dados somente de uma das peças.Nenhum método instrumental de análise vocal consegue fornecer todas as informações da fisiologia e fisiopatologia vocal, que são importantes para ó diagnóstico e manejo dos problemas vocais. READ (1992) relatou que o número de sistemas de avaliação da voz humana disponíveis já é bastante grande e cada um deles apresenta vantagens e desvantagens, não existindo nenhum sistema perfeito e insubstituível capaz de realizar avaliação vocal completa. Novos estudos e instrumentos que avaliem a função da laringe devem ser testados e desenvolvidos para o melhor entendimento e aprimoramento do seu produto: a voz humana.Este artigo relata o uso de um novo instrumento de análise vocal baseado na aplicação de fundamentos da transferência de calor, fenômeno físico jamais explorado anteriormente na análise da produção da voz. Através da distribuição de temperatura na cavidade oral, o método explora diferenças entre o padrão de fluxo aéreo e o fechamento das pregas vocais de indivíduos com voz normal e tem potencial para utilização em indivíduos disfônicos para a detecção de doenças precoces das pregas vocais.
EDITORIAL
Authors: Vargas J. V. C.
Published: November 2018

The third issue of RETERM – Thermal Engineering consolidates the journal as an official publication of the Brazilian Society of Mechanical Sciences (ABCM). The journal continues to be divided in two main sections: science and technology. The former is directed to publish complete articles that deal with fundamental advances in heat transfer and fluid mechanics, new physical insights, and novel experimental and analytical methods that have great appeal for the industry community, and the latter is designed to comprise informative articles that document modern engineering applications, or general advances in industry. Particularly, in this issue, the best articles written in English language, presented at the 9th Brazilian Congress of Thermal Engineering and Sciences, ENCIT 2002, held in Caxambu, MG, from October 15th to 18th, 2002, were selected by the Associate Technical Editors of RETERM, according to the scientific criteria of the journal. The idea is to increase the industrial and scientific impact of the research results presented in the Congress. The institutional support from the Brazilian Society of Industrial Machinery and Equipments (ABIMAQ), continues to strengthen our belief in the success of this enterprise. To open a perspective to the maintainance and continuity of RETERM, we invite the readers from the industrial community to contact our staff for subscriptions and publicity in RETERM. For the next issues we continue to welcome technical articles from both the scientific and the industrial communities to either section of RETERM, and contributions to the other sections of the journal, and suggestions for new sections as well. We also welcome response and comments from our readers that will certainlly help the success of RETERM.
A NUMERICAL SCHEME FOR SOLVING CREEPING FLOWS
Authors: Navarro H. A. , Ferreira V. G.
Published: November 2018

This work shows an extension of the generalized Peaceman and
Rachford alternating-direction implicit (ADI) scheme for simulating
two-dimensional fluid flows at low Reynolds numbers. The
conservation equations are solved in stream function - vorticity
formulation. We compare the ADI and generalized ADI schemes, and
show that the latter is more efficient to simulate a creeping flow.
Numerical results demonstrating the applicability of this technique are
also presented.
NUMERICAL SIMULATION OF FCC RISERS
Authors: Souza J. A. , Vargas J. V. C. , Von Meien O. F. , Martignoni W.
Published: November 2018

The catalytic cracking of hydrocarbons in a FCC riser is a very complex
physical and chemical phenomenon, which combines a three-dimensional,
three-phase fluid flow with a heterogeneous catalytic cracking kinetics.
Several researchers have carried out the modeling of the problem in different
ways. Depending on the main objective of the modeling it is possible to find
in the literature very simple models while in other cases, when more
accurate results are necessary, each equipment is normally treated separately
and a set of differential and algebraic equations is written for the problem.
The riser reactor is probably the most important equipment in a FCC plant.
All cracking reactions and fuel formation occur during the short time (about
4-5s) that the gas oil stays in contact with the catalyst inside the riser. This
work presents a simplified model to predict the, temperature and
concentrations in a FCC riser reactor. A bi-dimensional fluid flow field
combined with a 6 lumps kinetic model and two energy equations (catalyst
and gas oil) are used to simulate the gas oil cracking process. Based on the
velocity, temperature and concentration fields, it is intended, on a next step,
to use the second law of thermodynamic to perform a thermodynamic
optimization of the system.
Relationships between incivility and stress and self-efficacy among nursing students in clinical settings
Authors: Hong Eunhee , Lee HyeJin , Dee Vivien , Kim Younglee
Published: November 2018

Background: In nursing education, clinical practice is a crucial process for students to learn and practice knowledge and skills for becoming healthcare professionals.Objective: To investigate the effects of the experience of incivility on nursing students’ stress and self-efficacy in clinical settings.Methods: A descriptive cross-sectional study was conducted using self-administered surveys by a convenience sample of 195 nursing students in South Korea. The surveys included sociodemographic questions, the 13-item Korean version of Uncivil Behavior in Clinical Nursing Education (K-UBCNE), the 24-item Korean versions of Beck-Srivastava Stress Inventory (K-BSSI), and the 24-item of Academic Self-Efficacy (ASE).Results: The average age of our sample was 22.33 years (± 2.39). Among 195 study participants, junior students were 123 (63.1%) and senior students were 72 (36.9%). Mean score of total incivility by the K-UBCNE among the seniors was significantly higher than the juniors (t = -2.985, p = .002). Pearson correlations results indicated that the nursing students’ incivility experience was positively correlated with the K-BSSI (r = .679, p < .01), and the ASE (r = .680, p < .01). Lastly, Clinical Education Environment (t = 1.985, p = .049), Undesired Role Model (t = 6.650, p = .000) and Interpersonal Conflict (t = 2.486, p = .014) from K-BSSI were the predictors for incivility, F(7, 195) = 28.110, p = 000.Conclusions: Incivility adversely influences students’ learning. Nurse educators and RNs should recognize the serious implications of incivility and develop effective interventions to combat incivility. Further studies of stress, self-efficacy, and incivility in the clinical sites are warranted.
Teachers’ Attitude towards Teaching of Sexuality Education in Federal Government Colleges in Nigeria - Implications for Counselling
Authors: Onoyase Anna
Published: November 2018

The study investigated the attitude of teachers towards the teaching of sexuality education in federal government colleges in Nigeria. In order to carry out the investigation, three hypotheses were formulated. An instrument known as “teachers’ attitude towards teaching of sexuality education” (TATTOSE), was used to obtain information from the respondents. The instrument had a reliability coefficient of 0.79. It also had language appropriateness, content and facial validity. Four research assistants were used to administer 580 copies of the questionnaire to the respondents. Five hundred and twenty eight copies were retrieved showing 91.03 percent return rate. The data collected from the field were analyzed using t-test statistics. The research found out that there was no significant difference in the attitude of male and female teachers towards the teaching of sexuality education, that there was significant difference in the attitude of less experienced and experienced teachers towards the teaching of sexuality education. Finally, the study also revealed that there was no significant difference in the attitude of married and unmarried teachers towards teaching of sexuality education in Nigeria. One of the recommendations is that a curriculum of sexuality education should be drawn up for secondary schools.
Educating the Legal Imagination. Special Issue on Active Learning and Teaching in Legal Education
Authors: Del Mar Maksymilian
Published: November 2018

Educating the Legal Imagination. Special Issue on Active Learning and Teaching in Legal Education

This paper presents a basic model of the imagination and offers pedagogical resources and activities for educating three related abilities to imagine. The basic model is that to imagine is to combine the process of awareness, framing and distancing, and the process of, simultaneously actively participate, by doing things with and thanks to artefacts. Artefacts, in turn, are fabricated forms (here, forms of language) that signal their own artifice and invite us to do things with them, across a spectrum of sensory, kinetic, and affective abilities. Modelled in this way, imagination plays a crucial role in legal reasoning, and is exemplified by the following kinds of artefacts in legal discourse: fictions, metaphors, hypothetical scenarios and figuration. These artefacts and their related processes of imagination are vital to legal reasoning at many levels, including the level of the individual lawyer or judge, the level of interaction in courtrooms, and the level of legal language over time. The paper offers nine learning activities corresponding to educating three abilities in the legal context: 1) to take epistemic distance and participate; 2) to generate alternatives and possibilities; and 3) to construct mental imagery.
Współczesne wzorce kobiecości w kulturze rosyjskiej (na przykładzie serialu Мамочки)
Authors: Pasternak Katarzyna
Published: November 2018

The article discusses the topic of defining femininity in Russia on the basis of cultural patterns existing in society. The subject of the research is a woman in Russian tv series Мамочки. The article also examine the role oft he media in creating new reality. The research tool which has been used in this publication is a TV series – understood as a text of culture. Using the content and visual images included in the tv series, the specifics of gender roles in contemporary Russia have been pointed out.
John Henry Newman y su idea de la universidad en el siglo XXI
Authors: Rumayor Miguel
Published: November 2018

En este artículo se aborda la actualidad de algunos aspectos de la universidad en la filosofía educativa de John Henry Henry Newman. Concretamente, el documento tratará de demostrar cómo las ideas del pensador inglés son válidas para reorientar la crisis conceptual en la que se halla sumida esta institución en nuestros días. En primer lugar se criticarán, bajo el prisma de Newman, los problemas asociados al pragmatismo educativo que invade las aulas universitarias y la sola orientación de los alumnos hacia el mercado de trabajo. Por otra parte, se expone la importancia y la necesidad de la verdad en las aulas y el prestigio del profesor como guía comprometido en la búsqueda de la misma. Ambas ideas defendidas por Newman han desaparecido de muchas universidades occidentales de nuestro tiempo, con las negativas consecuencias que eso conlleva. Además, Newman  propone la promoción y el desarrollo de la expansión de la mente de los universitarios gracias a las enseñanzas recibidas. Esta se dará en todas las disciplinas, con lo que este autor denomina como desarrollo del “hábito filosófico”, el cual, como se explicará en este documento, consiste en orientar las materias más allá de sus dimensiones técnicas y de utilidad, creando en la mente de los alumnos una verdadera interdisciplinariedad de las ciencias. También se detallará en el escrito cómo, una vez que se empieza a alcanzar esta meta, objetivo de la universidad liberal que promueve Newman, los miembros de la comunidad académica podrán vincularse personalmente a la llamada gratuidad del saber y a los beneficios personales que otorga la vida académica. Estarán cimentando una verdadera alma mater universitaria, que se expandirá y ganará prestigio por el servicio que presta a la sociedad.
La FP dual desde la perspectiva del profesorado: elementos que condicionan su implementación en los centros
Authors: Pineda-Herrero Pilar , Ciraso-Calí Anna , Arnau-Sabatés Laura
Published: November 2018

El sistema de formación profesional dual (FPD) es actualmente uno de los más valorados a nivel internacional y se está extendiendo a muchos países como una medida para mejorar la formación de los jóvenes, reducir las tasas de desempleo juvenil y ajustar la formación al mundo laboral.Tras el comienzo de la implementación en España en 2013, los datos disponibles muestran un incremento progresivo de la participación de alumnado, centros y empresas. Sin embargo, es necesario analizar la percepción acerca de los agentes clave, como el profesorado, sobre los elementos que facilitan o que dificultan el desarrollo del sistema; éste es el objetivo de este estudio.Se administró un cuestionario diseñado ad hoc a una muestra representativa de centros formativos (equipos directivos, tutores y coordinadores) de cinco Comunidades Autónomas.Los resultados ponen de manifiesto algunos elementos positivos, como la decisión de realizar FPD por consenso y la motivación del alumnado. Sin embargo, otros resultados evidencian dificultades por parte de los centros a la hora de adaptarse a la implementación de la FPD: carencias formativas del profesorado acerca de la FDP, insuficiencia de recursos, falta de reconocimiento de la función que desempeña el profesorado y la falta de tiempo de los tutores de centro. Los análisis indican que los centros públicos expresan más dificultades; y que el profesorado en los centros donde ya se  está implementando la FPD percibe unas condiciones más favorables, identificando menos barreras, respecto a los que todavía no han empezado la implementación. El estudio pone las bases para futuras investigaciones más específicas sobre estos factores clave de implementación y sobre su relación con los resultados de aprendizaje en el alumnado.
Lectura, ocio y rendimiento académico en estudiantes universitarios del área socioeducativa
Authors: Elche María , Sánchez-García Sandra , Yubero Santiago
Published: November 2018

Introducción: En los últimos años se ha potenciado el interés de la investigación en torno a las variables que determinan el éxito académico dentro del ámbito universitario. Diferentes estudios han analizado el papel de la lectura en el rendimiento pero, sin embargo, no se ha considerado la relación de la lectura y el ocio en el éxito académico de los universitarios. Método: El objetivo de esta investigación es analizar cómo se inserta la lectura voluntaria en el tiempo de ocio de los estudiantes universitarios y analizar la influencia de la relación del ocio y de la lectura con el éxito académico en la universidad. Se ha empleado el Cuestionario de Hábitos de Lectura, la Escala de Actividades de Tiempo Libre y una medida del rendimiento. El cuestionario fue completado por 1614 estudiantes universitarios. Resultados: Los resultados confirmaron la relación del rendimiento académico con el ocio cultural, junto al tecnológico y con las prácticas de lectura, especialmente de tipo profesional. Discusión: Sería necesario seguir profundizando en esta línea de investigación, con el fin de diseñar propuestas de intervención en la universidad centradas en la mejora de las habilidades de lectura y de la gestión del tiempo de ocio.
À vos marques, prêts1, partez !
Authors: Raynauld Vincent
Published: November 2018

À la suite de la tenue de l’atelier intitulé « Qu’arrive-t-il après le doctorat ? Défis, pratiques et stratégies pour affronter l’“après-thèse” » qui a été organisé par la professeure Sule Tomkinson dans le cadre du 55e Congrès de la Société québécoise de science politique et 7e Congrès international des associations francophones de science politique, cet article s’intéresse aux défis et aux possibilités qui se présentent pour un grand nombre de doctorants désireux de décrocher un poste de professeur menant à la permanence et entreprendre une carrière dans le monde universitaire. De manière plus spécifique, cet article propose une série de stratégies permettant aux candidats à un poste de professeur menant à la permanence de mieux se positionner dans le cadre de leurs études doctorales et de leur recherche d’emploi.