bluuebunny/crossref_metadata_2025 huggingface dataset:
Barriers to research activities as perceived by medical university students: A cross-sectional study
Authors: Dadipoor Sakineh , Ramezankhani Ali , Aghamolaei Teamur , Safari-Moradabadi Ali
Published: November 2018

Context: The importance of research is revealed by the fact that the top seven science producing countries in the world are the same seven countries worldwide in terms of the research facilities. Aim: To explore the barriers to research activities among the students of the Hormozgan Medical University. Settings and Design: A total of 400 students affiliated with the Hormozgan University of Medical Sciences participated in this cross-sectional study. Methods: The sampling method was proportional stratified, and the data collection instrument was a tripartite questionnaire that comprised demographic information, personal barriers, and organizational barriers. Statistical analysis: The data were statistically analyzed by the Statistical Package for the Social Sciences (SPSS) software (V.16.0, SPSS Inc., Chicago, IL, USA) using descriptive statistics as well as the independent sample t-test, one-way analysis of variance, and Pearson’s correlation coefficient. The level of significance was set at P < 0.05. Results: The most prevalent personal barriers were inadequate knowledge of research methodology (2.91±1.24) and inadequate skill in research conduction (2.89±1.36). In the realm of organizational barriers, limited access to information sources was the most prevalent barrier (2.75±2.27). The results showed that researcher students encounter more of the organizational barriers (56.13±13.90), whereas non-researcher students faced more of the personal barriers (53.80±10.95). Conclusion: Establishing access to high-speed Internet system, raising students’ awareness of research methodology through workshops, encouraging and motivating students for research work, and using online sources can help in removing the barriers to research activities.
Gender differences in practicing standard precautions against blood-borne pathogens among surgeons at a tertiary care center: A cross-sectional study
Authors: Alsaigh Shahad Yousefr , Alasmari Amal Aboudr , Hakeem Anadel Hassanr , Aloushan Amairah Fahadr , Saleh Fatemah Saleh Binr , Althubaiti Alaa , Yousef Zeyad
Published: November 2018

Background: Surgeons are at an increased risk of contracting blood-borne pathogens. The aim of this study was to evaluate gender difference, surgical position, surgical experience, and subspecialty regarding surgeons’ compliance to standard precautions. Methods: A cross-sectional questionnaire-based study was performed using a purposive sampling. A total of 241 surgeons were surveyed from June 2017 to January 2018. Results: In total, 179 (74.3%) males and 62 (25.7%) females completed the questionnaire. The gender difference was evident when the type of surgery was extremely important in influencing the decision on wearing double gloves (DGs); 108 (60.3%) male surgeons versus 27 (43.5%) female surgeons (P = 0.022). Although a total of 17 (30.3%) surgeons reported being extremely and very concerned about contracting human immunodeficiency virus through their work, they had never tried DG (P = 0.027). Conclusion: This study revealed that the decision of wearing DG was affected by several factors. Surgeons’ decision to wear DG was influenced by the type of surgery. This study showed that most surgeons reported lack of adherence to barrier precaution measures.
Macroeconomic effects of unemployment benefits in small open economies: a stock–flow consistent approach*
Authors: Byrialsen Mikael Randrup , Raza Hamid
Published: November 2018

This paper attempts to analyse the macroeconomic effects of unemployment benefits in a small open economy. We adopt a stock–flow consistent (SFC) approach with an emphasis on the dynamics of the labour market. We numerically solve the model using a combination of estimation and calibration to generate statistics for our key variables, reflecting features of the Danish economy. We then analyse the effects of a fall in the unemployment compensation rate on the economy. The results indicate that a fall in the compensation rate at a macro level leads to a trade-off between a fall in aggregate demand and a rise in net exports. Due to this trade-off, the net effect of a fall in the compensation rate on the aggregate unemployment rate tends to be weak. Our analyses in this paper raise several questions on the existing views regarding unemployment benefits adopted by a large strand of the economic literature.
Effects of working memory and attentional control training and their transfer onto fluid intelligence in early and late adulthood
Authors: Zając-Lamparska Ludmiła , Trempała Janusz
Published: November 2018

Background

The interest in the possibility of improving cognitive functioning through training of basic cognitive processes is growing. This possibility is of particular importance for older adults, whose cognitive functions are weakened, and who may need cognitive rehabilitation. However, improvement of the performance in the tasks being trained is not the only goal of basic cognitive processes training. Far transfer, onto tasks different to the ones trained, and engaging other (usually complex) processes, including fluid intelligence, is an important goal of such training. Yet, meta-analyses suggest that results of studies on the far transfer phenomenon vary, and are not conclusive.

Participants and procedure

One hundred and eighty healthy volunteers took part in this study. They were divided into groups: Experimental 1 (working memory training), Experimental 2 (attentional control training) and Control (non-contact). Each of these groups included participants from the two age subgroups: early and late adulthood. Training involved 7 appointments and lasted for about 4 weeks. Additional measurements, including an assessment of fluid intelligence, were performed on each group at baseline, and at the end of training.

Results

Our results suggest that (a) the training of basic cognitive processes in adults leads to an improvement in the correctness, but not the speed, at which tasks are performed, (b) there is a transfer effect onto fluid intelligence, but this effect is weak, and (c) the effects of basic cognitive process training depend on the kind of trained tasks, age of participants and the interactions between these two factors: working memory training is equally as effective in both age groups, whereas training of attentional control is particularly effective among older individuals, and has limited efficacy for young adults.

Conclusions

Finally, one can conclude that the effectiveness of basic cognitive function training is limited. However, it can be significant, even in the aspect of transfer, under conditions related to the type of trained tasks and the age of the participants.
A mechanism for biogenic production and emission of MEK from MVK decoupled
from isoprene biosynthesis
Authors: Cappellin Luca , Loreto Francesco , Biasioli Franco , Pastore Paolo , McKinney Karena
Published: November 2018

Abstract. Methyl ethyl ketone (MEK) is an important compound in atmospheric chemistry. While attention has been paid mostly to anthropogenic sources of MEK, recently it has been shown that biogenic sources are globally as important as anthropogenic ones. However, the origin of biogenic MEK has yet to be completely elucidated. We present the full mechanism by which within-plant transformation of MVK and, to a minor extent, of 2-butanol and 3-buten-2-ol, is a source of biogenic MEK. Such transformation is observed in red oak for both exogenous MVK, taken up from the atmosphere, and endogenous MVK generated within plant upon stress (e.g. heat stress). Endogenous MVK emitted by plants is typically explained by within-plant oxidation of isoprene caused by oxidative stress. In this study we show that MVK and MEK emission caused by heat stress is not related to isoprene in isoprene-emitting plants, implying that the massive carbon investment that plants commit to isoprene production is not explained by a direct antioxidant role. The presented mechanism can be important for inclusion in plant emission and in plant-atmosphere interaction models.
Weaving of biomineralization framework in rotaliid foraminifera: implications for paleoceanographic proxies
Authors: Nagai Yukiko , Uematsu Katsuyuki , Chen Chong , Wani Ryoji , Tyszka Jarosław , Toyofuku Takashi
Published: November 2018

Abstract. Elemental and/or isotopic signatures of calcareous tests of foraminifera are
commonly used to reconstruct paleoenvironmental conditions. A major problem,
often referred to as the “vital effect”, is that such geochemical signatures
stored in inorganic calcium carbonates differ greatly under the same
environmental conditions, as well as between taxa, species, individuals, etc.
This effect was previously explained by relative contributions between
passive vs. active ion transport patterns, but their details are still under
investigation. In this study, the functional role of pseudopodial structures
during chamber formation is elucidated by detailed observation of
Ammonia beccarii (Linnaeus, 1758) using a time-lapse optical
imaging system and high-resolution electron microscopy. We document triple
organic layers sandwiching carbonate precipitation sites for the first time.
The three major organic layers (outer organic layer, primary organic sheet,
and inner organic layer) are formed by an initial framework of pseudopodia
overlaid with further layer-like pseudopodia. The primary organic sheet seems
to facilitate early calcium carbonate nucleation, then entrapped by double
precipitation sites. We further show that calcification starts when
outer or inner organic layers still exhibit tiny gaps (holes within the
framework) that may serve as pathways for passive ion exchange (e.g.
Mg2+) between seawater and the confined precipitation space.
Nevertheless, the majority of wall thickening occurs when the precipitation
site is completely isolated from seawater, which implies active ion exchange.
This may explain the differences in Mg ∕ Ca ratios in early and later stages of
calcification observed in previous studies. Our study provides insight
into resolving a key “missing piece” in understanding foraminiferal
calcification through culture experiments and in-depth observations of living
animals. Our findings contribute to interpreting and understanding
biogeochemical proxies by showing that the “vital effect”, specifically
elemental and isotopic ratios along chamber walls, is directly linked to
spatio-temporal organization of the “biomineralization sandwich” controlled
by the three major organic layers.
The value of satellite remote sensing soil moisture data and the DISPATCH algorithm in irrigation fields
Authors: Fontanet Mireia , Fernàndez-Garcia Daniel , Ferrer Francesc
Published: November 2018

Abstract. Soil moisture measurements are needed in a large number of applications such
as hydro-climate approaches, watershed water balance management and
irrigation scheduling. Nowadays, different kinds of methodologies exist for
measuring soil moisture. Direct methods based on gravimetric sampling or time
domain reflectometry (TDR) techniques measure soil moisture in a small volume
of soil at few particular locations. This typically gives a poor description
of the spatial distribution of soil moisture in relatively large agriculture
fields. Remote sensing of soil moisture provides widespread coverage and can
overcome this problem but suffers from other problems stemming from its low
spatial resolution. In this context, the DISaggregation based on Physical And
Theoretical scale CHange (DISPATCH) algorithm has been proposed in the
literature to downscale soil moisture satellite data from 40 to 1 km
resolution by combining the low-resolution Soil Moisture Ocean Salinity
(SMOS) satellite soil moisture data with the high-resolution Normalized
Difference Vegetation Index (NDVI) and land surface temperature (LST)
datasets obtained from a Moderate Resolution Imaging Spectroradiometer
(MODIS) sensor. In this work, DISPATCH estimations are compared with soil
moisture sensors and gravimetric measurements to validate the DISPATCH
algorithm in an agricultural field during two different hydrologic scenarios:
wet conditions driven by rainfall events and wet conditions driven by local
sprinkler irrigation. Results show that the DISPATCH algorithm provides
appropriate soil moisture estimates during general rainfall events but not
when sprinkler irrigation generates occasional heterogeneity. In order to
explain these differences, we have examined the spatial variability scales of
NDVI and LST data, which are the input variables involved in the downscaling
process. Sample variograms show that the spatial scales associated with the
NDVI and LST properties are too large to represent the variations of the
average soil moisture at the site, and this could be a reason why the DISPATCH
algorithm does not work properly in this field site.
Announcement of Retraction
Authors: Pérez Salomón , Gonzalez Carolina , Oparinde Adewale , Birol Ekin , Zeller Manfred
Published: November 2018

The editorial board announced this article has been retracted on November 28, 2018.If you have any further question, please contact us at: jas@macrothink.org Article Title: The Role of Respondents’ Market Participation in Consumer Acceptance of Seeds and Grains of an Iron-Enriched Bean Variety in GuatemalaAuthor/s: Salomón Pérez, Carolina Gonzalez, Adewale Oparinde, Ekin Birol, Manfred ZellerJournal Title: Journal of Agricultural StudiesISSN 2166-0379       Volume and Number: Vol. 6, No. 4, 2018Pages: 36-53DOI: 10.5296/jas.v6i4.13916
Vaccination and Associated Adverse Events in Dogs Previously Treated for Primary Immune-Mediated Hemolytic Anemia
Authors: Moon Alaina , Veir Julia
Published: November 2018

This study described the rate of vaccine reactions in a population of dogs receiving vaccines after diagnosis of primary immune-mediated hemolytic anemia (IMHA). A secondary objective was to describe the time elapsed between vaccination and initial diagnosis of IMHA. A medical record search identified cases meeting criteria for primary IMHA. Owners and referring veterinarians were surveyed regarding vaccination of the dog following diagnosis. Referring veterinarians were surveyed regarding vaccination prior to diagnosis of IMHA. A completed survey was returned in 44 cases. Twenty-two dogs received vaccinations after diagnosis, and 22 dogs did not. The median time elapsed between vaccination and initial diagnosis was 280 days. No dog was vaccinated within 30 days of diagnosis. Two of the following possible reactions were noted out of 22 dogs vaccinated: vomiting and urticarial eruption in a dog administered a rabies and canine distemper vaccine, and recurrent anemia in a dog administered a rabies vaccine. The rate of vaccine reactions was higher than previously reported, although the time period evaluated was longer than in previous studies. The relationship between initial vaccination and development of IMHA, and between vaccination and vaccine reaction, in this population is uncertain and may reflect coincidence or differences in susceptibility.
Scopulariopsis brevicaulis Rhinosinal Infection in a Dog
Authors: Sri-Jayantha Loren , Matthews Kyle G. , Scharf Valery
Published: November 2018

A 1 yr old castrated male American Staffordshire terrier mix was treated for Scopulariopsis brevicaulis that was discovered during an evaluation of chronic rhinosinusitis. A sinusotomy was performed, with intraoperative infusion of amikacin-impregnated gel and systemic administration of postoperative amikacin. Antibiotic therapy was initially chosen because of historic culture of Mycoplasma. Fungal culture of the frontal sinus identified S. brevicaulis by combined phenotypic characterization and DNA sequencing after morphologic analysis failed to identify the organism. Systemic terbinafine therapy was instituted after fungal culture results were available. The patient recovered well and has had no clinical relapse of disease 3 yr after treatment. This is the first reported case of a fungal rhinosinusitis caused by S. brevicaulis in a dog. Reports of Scopulariopsis infections in humans indicate that treatment of S. brevicaulis infection is hampered by multidrug resistance; prognosis may be poor in people with invasive infections and is currently unknown in dogs. Multimodal therapy, including concurrent surgical and systemic intervention, may be necessary to optimize treatment success.
EDITORIAL
Authors: Vargas J. V. C.
Published: November 2018

Around the end of the twentieth century, nanotechnology appeared to be the new breakthrough, after the internet, for example. At that time, more efficient and affordable solar cells, green chemistry, quantum computing, lightweight composite aircraft, cell-size robots for medical applications were expected to be available soon. When the financial milestones did not become real, investors got disappointed and decided to rethink their plans. Yet today the perspectives are surprisingly upbeat. Currently, it is well known that restructuring matter at the nanoscale chemical and thermophysical properties change, so that systems that have no purpose at the macroscale, at the nanoscale become useful. In fact, several applications have already begun to appear such as in the oil and gas sector components, structured coatings, nanofluids, new cancer treatment drugs, and nanoviricides. Computer processor and memory manufacturers are already producing products with 32 nanometer components, so that the first commercial memristor (memory resistor) is expected to be launched at the end of 2013. In the renewable energy area, just to cite a few examples, low energy consumption nanostructured inexpensive LEDs are being developed to potentially last for years, carbon nanotubes have been used to drastically reduce precious materials content in proton-exchange fuel cell (PEMFC) electrodes and increase efficiency, and nanostructured thin films are being developed to boost photovoltaic performance and reduce costs, which demonstrated a 23.5 % efficient flexible solar panel operating a 2 MW pilot line at the National Renewable Energy Laboratory in the US. In comparison to market available 10 % efficient solar panels, this is a remarkable efficiency increase in capturing solar energy for practical use due to nanotechnology. This nanotechnological achievement challenges scientists to possibly change the currently fuel (fossil and bio) energy driven world into a solar energy driven one.
TEMPERATURE EFFECT ON THE STRENGTH OF ADHESIVELY BONDED SINGLE LAP JOINTS
Authors: Osanai K. R. , Reis J. M. L.
Published: November 2018

The purpose of this paper is to study some of the factors that affect the shear strength of Single Lap Joints (SLJ). Based in work conditions for different applications, tests were made in order to define the influence of geometry and temperature on the strength of SLJ under shear load. The adhesive used to make the joints was the epoxy adhesive ARC858 and it was tested under temperatures ranging between 21°C and 70°C and overlap length of 12.5mm and 18.75mm. Results of those tests showed that shear strength increased due to geometry with an overlap of 18.75mm and a great shear strength loss ranging from 30°C to 50°C. The failure mechanism was adhesive failure.
ANALYSIS OF SUB-GRID MODELING EFFECTS IN THE SIMULATION OF THE SINGLE-PHASE TURBULENT FLOW IN AN INDUSTRIAL CYCLONE SEPARATOR
Authors: Salvo R. V. , Souza F. J. , Martins D. A. M.
Published: November 2018

In the present work two turbulence modeling approaches, namely Large Eddy Simulation and Detached Eddy Simulation, are employed to predict turbulent, swirling flow within an industrial cyclone separator running at Reynolds number 267,000. The results from three LES models, Smagorinsky, dynamic and Yakhot, and the SST-DES model of Strelets have been compared to experimental results for the average axial and tangential velocities. The Navier-Stokes solver is based on an unstructured, finite volume, cell-centered algorithm such that the details of the geometry can be accurately represented. Based on the comparison with the experimental results, it has been found that the Yakhot model provides the most accurate predictions for the tangential velocities, whereas the dynamic LES and the Smagorinsky models overpredict it and the SST-DES model underpredicts it. However, the conclusions are different regarding the axial velocity. Implications of the turbulence modeling for the particle separation are discussed.
A MAGNETOHYDRODYNAMIC STUDY OF BEHAVIOR IN AN ELECTROLYTE FLUID USING NUMERICAL AND EXPERIMENTAL SOLUTIONS
Authors: Aoki L. P. , Maunsell M. G. , Schulz H. E.
Published: November 2018

This article examines a rectangular closed circuit filled with an electrolyte fluid, known as macro pumps, where a permanent magnet generates a magnetic field and electrodes generate the electric field in the flow. The fluid conductor moves inside the circuit under magnetohydrodynamic effect (MHD). The MHD model has been derived from the Navier Stokes equation and coupled with the Maxwell equations for Newtonian incompressible fluid. Electric and magnetic components engaged in the test chamber assist in creating the propulsion of the electrolyte fluid. The electromagnetic forces that arise are due to the cross product between the vector density of induced current and the vector density of magnetic field applied. This is the Lorentz force. Results are present of 3D numerical MHD simulation for newtonian fluid as well as experimental data. The goal is to relate the magnetic field with the electric field and the amounts of movement produced, and calculate de current density and fluid velocity. An u-shaped and m-shaped velocity profile is expected in the flows. The flow analysis is performed with the magnetic field fixed, while the electric field is changed. Observing the interaction between the fields strengths, and density of the electrolyte fluid, an optimal configuration for the flow velocity isdetermined and compared with others publications.
MODELLING OF HYDRODYNAMICS AROUND AN IMPERMEABLE BREAKWATER: COMPARISON BETWEEN PHYSICAL AND SPH NUMERICAL MODELING
Authors: Didier E. , Neves D. R. C. B. , Martins R. , Neves M. G.
Published: November 2018

This work presents the new developments and the validation of a Smoothed Particle Hydrodynamics (SPH) numerical model used in the National Laboratory of Civil Engineering (Laboratório Nacional de Engenharia Civil - LNEC) for studies in coastal engineering processes. Although the model requires a high CPU time, it proved to be very promising in the simulation of complex flows, such as the wave-structure interaction and the wave breaking phenomenon. For the SPH model validation, physical modeling tests were performed in one LNEC’s flume to study the interaction between an impermeable structure and an incident regular wave. The comparison between numerical and experimental results, i.e. free surface elevation, overtopping volume and pressure, shows the good accuracy of the SPH model to reproduce the various phenomena involving on the wave propagation and interaction with the structure, namely the wave breaking, the wave overtopping and the pressure field on the structure.
NUMERICAL INVESTIGATION OF TURBULENT FORCED CONVECTIVE FLOWS OVER A PAIR OF CIRCULAR CYLINDERS
Authors: Dos Santos E. D. , Da Silva F. M. V. , Acunha Jr. I. C. , Galarça M. M. , Isoldi L. A. , Rocha L. A. O.
Published: November 2018

The present study presents large eddy simulation (LES) of forced convective heat transfer in transient, two-dimensional, incompressible turbulent flows over a pair of cylinders with two different arrangements: 1) with two circular cylinders in tandem (both cylinders are in line with the streamwise direction of the flow, β = 0º) and 2) two side-by-side circular cylinders (where both cylinders are placed transversally to the streamwise direction of the flow, β = 90º). The dynamic Smagorinsky model is employed for the sub-grid treatment. The simulations are based on the finite volume method solution for the conservation equations of mass, momentum and energy. Both simulations are performed with Reynolds and Prandtl numbers of ReD = 22000 and Pr = 0.71, respectively. The results showed that the transient fluid dynamic and thermal patterns are strongly affected by the configuration of circular cylinders. The kind of arrangement led to a difference of nearly 20 % for time-averaged Nusselt number (NuD).
CONSTRUCTAL DESIGN OF A VORTEX TUBE FOR SEVERAL INLET STAGNATION PRESSURES
Authors: Marques C. H. , Isoldi L. A. , Dos Santos E. D. , Rocha L. A. O.
Published: November 2018

The present paper shows a numerical study concerned with the geometrical optimization of a vortex tube device by means of Constructal Design for several inlet stagnation pressures. In the present study, it is evaluated a vortex tube with two-dimensional axisymmetric computational domain with dry air as the working fluid. The compressible and turbulent flows are numerically solved with the commercial CFD package FLUENT, which is based on the Finite Volume Method. The turbulence is tackled with the k-ε model into the Reynolds Averaged Navier-Stokes (RANS) approach. The geometry has one global restriction, the total volume of the cylindrical tube, and four degrees of freedom: d3/D (the ratio between the diameter of the cold outlet and the diameter of the vortex tube), d1/D (the ratio between the diameter of the inlet nozzle and the diameter of the vortex tube), L2/L (the ratio between the length of the hot exit annulus and the length of the vortextube) and D/L (the ratio between the diameter of the vortex tube and its length). The degree of freedom L2/L will be represented here by the cold mass fraction (yc). In the present work it is optimized the degrees of freedom yc and d3/D while the other degrees of freedom and the global restriction are kept fixed. The purpose here is to maximize the amount of energy extracted from the cold region (cooling effect) for several geometries, as well as, investigate the influence of the inlet stagnation pressure over the optimal geometries. Results showed an increase of the twice maximized cooling heat transfer rate of nearly 330 % from 300 kPa to 700 kPa. Moreover, the optimization showed a higher dependence of (d3/D)o for the lower range of inlet pressures, while the optimization is more dependent of yc,oo for higher inlet stagnation pressures.
DYNAMICAL SIMULATION OF A VALVETRAIN MECHANISM: AN ENGINEERING EDUCATION APPROACH
Authors: Nunes M. A. A. , Silva R. C. , Oliveira A. B. S. , Peron G. C.
Published: November 2018

The present work aims to present a valvetrain model considering the dynamics functioning aspects of an Otto’s engine. The model will be constructed using Adams/View® software, which is a powerful modeling and simulating environment of dynamic systems. It allows building, simulating, refining and optimizing any mechanical system. In fact, the model will help engineering students to understand how the mechanism works, in terms of displacement, velocity and acceleration of the valve as a function of the time. It is also possible to know the behavior of the force in the spring as a function of the time and, finally, the torque applied in the cam due to a angular velocity input. Relative to spring force, during the Otto engine cycle, the cam lobe must be able to open and close the valve as fast and as smoothly as possible. The force responsible to close the valve is applied by the valve spring, which is also responsible for keeping contact between the cam lobe and the valve. Dynamic forces impose limits on cam and valve lift. Thus, the simulation model allows determining these forces and displacements through the cam rotation. As main objectives the authors wish to make available a model which is capable to show in 3D the animation of a valvetrain mechanism of an Otto engine, obtaining the main curves for analysis and evaluation of this mechanism performance.
BENCHMARKING OF TWO SYSTEMS FOR TRANSMISSION OF MOTION FOR A DOUBLE ACTION STIRLING ENGINE
Authors: E Paula R. B. , Antunes P. D. , Souza P. O. , Leme M. M. V.
Published: November 2018

In a four-piston Stirling engine, Siemens configuration, the displacement of the pistons is governed by the motion transmission element, which converts the reciprocating motion of pistons into rotary motion. This study aimed to evaluate the influence of the geometry of the transmission element in the mechanical efficiency of a Stirling engine. Analyses were performed using a mathematical computer simulation that uses the geometric and operating data of the engine to calculate the mechanical power and efficiency through a first order thermodynamic mathematical model, also known as the Schmidtmodel. First, an analysis was performed to evaluate the mechanical efficiency of the transmission element with a sinusoidal curve surface. Later, it was implemented in the transmission mechanism a segment based straight plans surface, and then the same analysis was performed with this new transmission element. The results showed that using the transmission element with segment based straight plans the engine showed a significant increase in efficiency. Moreover, one can observe an increase in the vibration of the system, making it necessary to develop an appropriate system for balancing.
A DIESEL ENGINE CONVERTED INTO OTTO CYCLE ENGINE: THE INFLUENCE OF THE SPARK ADVANCE ON ITS PERFORMANCE AND ON NOx EMISSIONS
Authors: Oliveira B. L. N. , Jaguaribe E. F. , Bezerra A. F. , Rumão A. S. , Queiroga B. L. C.
Published: November 2018

This paper analyzes the performance of a diesel engine converted into an Otto cycle engine and its Nitrogen dioxide emissions in terms of the spark advance variation. The tests were conducted on a Perkins diesel engine 1104C - 44TAG turbocharged, whose compression ratio was reduced to 9.33:1. After conversion the engine started operating with liquefied petroleum gas (LPG) and running just with stoichiometric mixtures. The tests have been limited to 10 to 40 kW, always at 1800 rpm. During the experiments the ignition advance angle ranged from 5º up to 27º (BTDC), using the increment of 5°, whenever possible. Particularly at 40 kW, the range of the ignition advance was 15º to 20º. The results showed a significant influence of the spark advance angle on the fuel consumption, on the temperature and on the NOx emissions, as well as on the magnitude of the generated power.
NUMERICAL SIMULATION OF INCOMPRESSIBLE FLOWS BY THE STABILIZED FINITE ELEMENT METHOD
Authors: Pereira V. D. , Romão E. C. , Silva J. B. C. , De Moura L. F. M.
Published: November 2018

The fast progress has been observed in the development of numerical and analytical techniques for solving convection-diffusion and fluid mechanics problems. Here, a numerical approach, based in Galerkin Finite Element Method with Finite Difference Method is presented for the solution of a class of non-linear transient convection-diffusion problems. Using the analytical solutions and the L2 and L∞ error norms, some applications is carried and valuated with the literature.
EDITORIAL
Authors: Ordonez J. C.
Published: November 2018

I would like to direct the attention of the reader to thermal energy storage. Increased interest in on-site renewable power generation mainly through direct energy conversion using photovoltaic systems together with policy changes in support of “net-zero energy” buildings are bringing a new wave of interest on energy storage.  Despite the progress seen in electrochemical storage, cost, cyclability and life-time remain as major hurdles to be overcome. This confluence of need for energy storage and lack of robust solutions opens an opportunity for a renewed look at thermal energy storage. This is a field, in which problems are by nature dynamic and one in which interesting mathematical problems arise (e.g. phase change, interface tracking). It is also a field that continues to serve as a great playground in which to explore advances in applied thermodynamics (e.g construtal theory, entropy generation minimization) and one that reminds us clearly of the goal of making the best possible with the available energy and exergy at our disposal.
DESIGN OF A CENTRIFUGAL COMPRESSOR FOR NATURAL GAS
Authors: Kurauchi S. K. , Barbosa J. R.
Published: November 2018

This work presents the design of a centrifugal compressor for natural gas in three steps. The first step is the 1-D preliminary design heavily based on empirical data, only the design point was considered here. The second step is the flow analysis in the meridional plane. The last step is the CFD analysis to verify if the 1-D design methodology is adequate. The CFD simulations showed good agreement with the results obtained in the preliminary design, proving the importance of empirical data in the design of centrifugal compressors.
ANALYSIS OF AN EXTREME LOSS OF COOLANT IN THE IPR-R1 TRIGA REACTOR USING A RELAP5 MODEL
Authors: Reis P. A. L. , Costa A. L. , Pereira C. , Veloso M. A. F. , Soares H. V. , Mesquita A. Z.
Published: November 2018

The RELAP5/MOD3.3 code has been applied for thermal hydraulic analysis of power reactors as well as nuclear research reactors with good predictions. The development and the assessment of a RELAP5 model for the IPR-R1 TRIGA have been validated for steady state and transient situations. The reactor is located at the Nuclear Technology Development Centre (CDTN), Brazil. It is a 250 kW, light water moderated and cooled, graphite-reflected, open pool type research reactor. In this work, an extreme transient case of loss of coolant accident (LOCA) has been simulated. For this type of analysis, the automatic scram of the reactor was not considered because the main aim was to verify the evolution of the fuel elements heating in the absence of coolant. The temperature evolutions are presented as well as an analysis about the temperature safety limits.
SENSITIVE ANALYSIS OF A COAL COMBUSTION MODEL ON A DROP TUBE FURNACE
Authors: Zimmer L. , Pereira F. M. , Schneider P. S.
Published: November 2018

In the present work a one-dimensional model for coal combustion in a Drop Tube Furnace (DTF) is developed. The equations that characterize the flow, heat transfer phenomena and coal combustion reactions are programmed in a FORTRAN90 language code. The results are compared with a reference model and experimental data, showing good agreement. A sensitivity study is performed to understand the behavior of coal combustion due to changes of some working parameters of the DTF. From the variation of the oxygen concentration, working temperature and input flow rates the response of the coal combustion in terms of unburned fraction can be obtained.
CEREBROSPINAL FLUID DRAINAGE DEVICES: EXPERIMENTAL CARACTERIZATION
Authors: Bim C. , Pinotti M. , Camilo J. R. , Maset A. L. , Mansur S. S. , Vieira E. D. R.
Published: November 2018

Hydrocephalus is a pathophysiology due to the excess of cerebrospinal fluid in the brain ventricles and it can be caused by congenital defects, brain abnormalities, tumors, inflammations, infections, intracranial hemorrhage and others. Hydrocephalus can be followed by significant rise of intraventricular pressure due to the excess of production of cerebrospinalfluid over the absorption, resulting in a weakening of intellectual functions, serious neurological damage (decreased movement, sensation and functions), critical physical disabilities and even death. A procedure for treatment involves the placement of a ventricular catheter into the cerebral ventricles to divert/drain the cerebrospinal fluid flow to a bag outside of the patient body – provisory treatment known as external ventricular drainage (EVD). Another option is the permanent treatment, internal ventricular drainage (IVD), promoting the cerebrospinal fluid drainage to other body cavity, being more commonly the abdominal cavity. In both cases, EVD and IVD, it is necessary to use of some type of neurological valve in order to control the flow of cerebrospinal fluid. In the present work is proposed an experimental procedure to test the hydrodynamic behavior of a complete drainage system, or parts of them, in order to verify its performance when subjected to pressure gradients found in the human body. Results show that the method is well adapted to quantify the pressure drop in neurological systems.
INFLUENCE OF ASPECT RATIO IN THE TURBULENT CONVECTION IN CAVITIES
Authors: Guimarães R. M. , Mariani V. C. , Mendonça K. C.
Published: November 2018

The purpose of this study is to know the air distribution in a conditioned room, through the numerical investigation of the influence of aspect ratio in the thermal and fluid dynamics behavior of a turbulent flow. To achieve that objective, some simulations were done of the flow inside a rectangular room, where the air enters through an opening in the top of one wall and leaves the room through an opening in the bottom of the opposite wall. The Reynolds mean equations are used, with the turbulence model RSM BSL (Reynolds Stress Model - Baseline) to solve four cases, with different geometries. It was concluded that, in general, the turbulence model used in this work is capable to predict quite well the fluid dynamics behavior of the flow, which is influenced by the room length, but not by its width.
SIMULATION OF A FLOW THROUGH A RIGID POROUS MEDIUM SUBJECTED TO A CONSTRAINT
Authors: Saldanha da Gama R. M. , Pedrosa Filho J. J. , Martins-Costa M. L.
Published: November 2018

This work uses a previuosly proposed mathematical model to study the filling up of an unsaturated rigid porous medium by a liquid identifying the transition from unsaturated to saturated flow. This model accounts for the physical upper bound of the fluid fraction that depends on the volume of the pores and employs a mixture theory to describe the flow. The mathematical description of the phenomenon leads to a nonlinear hyperbolic system. In order to solve this system, the space of admissible solutions must be enlarged to admit discontinuous solutions that may be shock waves. The complete solution of a Riemann problem associated to the system of conservation laws satisfying the constraint given by the saturation upper bound is presented. Some meaningful results are presented and discussed.
EDITORIAL
Authors: Mariano A. B.
Published: November 2018

The population growing awareness regarding the use of fossil fuels, especially with respect to correlated environmental issues, led to an increased interest in renewable energy sources in the last decade. Around 200 years ago, biomass lost its historic leadership as a source for coal production. Next, it was seen the rapid growth in the use of petroleum and natural gas, and in this way, the use of biomass was limited particularly to agricultural regions. Currently, due to the responsible use of forests and large areas of reforestation, the use of biomass has conquered international attention and the demand for using wood-based materials is increasing. The biomass is not restricted to wood products, but also to any product of biological origin, which could be utilized as fuel, or for other industrial purpose and, in addition, has the advantage of being renewable. The existing challenges are the development of efficient productive chains around a product and total use of the material, including the use of the generated residuals, and the verticalisation of industrial plants. Therefore, the Thermal Engineering community could contribute to the development of technologies for coupling processes such as conversion of residuals into products of commercial value or their use for power generation. There is much opportunity for improvement in the wood, sugar cane or soybean industries, considering that all of them use heat to convert the substrates into products. Replacing natural gas or electricity used to generate heat by renewable sources such as residual biomass pellets without loss of efficiency could greatly increase the energetic efficiency of a plant, as well as reduce environmental impact.
NEAR INFRARED LIGHT HEATING OF SOFT TISSUE PHANTOMS CONTAINING NANOPARTICLES
Authors: Eibner S. , Jaime R. A. O. , Lamien B. , Basto R. L. Q. , Orlande H. R. B. , Fudym O.
Published: November 2018

The objective of this paper is to investigate the effect of the addition of nanoparticles to soft tissue phantoms, aiming at the enhancement of photothermal therapy for cancer. The phantoms were made of Polyvinyl chloride-plastisol (PVC-P), with two different nanoparticles, namely, titanium dioxide nanoparticles (TiO2) and silica nanoparticles (SiO2). A phantom without nanoparticles and a phantom containing a thermal paste were also manufactured for comparison purposes. The PVC-P phantom is transparent to the near infrared laser light, whereas the addition of titanium dioxide nanoparticles modified the optical properties enhancing the local heating, as demonstrated through experiments with a laser-diode and an infrared camera.
DEVELOPMENT OF METHODS FOR MONITORING AND CONTROLLING POWER IN NUCLEAR REACTORS
Authors: Mesquita A. Z. , Rezende H. C. , Santos A. A. C. , Silva V. V. A.
Published: November 2018

Power monitoring of nuclear reactors is normally done by means of neutronic instruments, i.e. by the measurement of neutron flux. The greater the number of channels for power measuring the greater is the reliability and safety of reactor operations. The aim of this research is to develop new methodologies for on-line monitoring of nuclear reactor power using other reliable processes. One method uses the temperature difference between an instrumented fuel element and the pool water below the reactor core. Another method consists of the steady-state energy balance of the primary and secondary reactor cooling loops. A further method is the calorimetric procedure whereby a constant reactor power is monitored as a function of the temperature-rise rate and the system heat capacity. Another methodology, which does not employ thermal methods, is based on measurement of Cherenkov radiation produced within and around the core. The first three procedures, fuel temperature, energy balance and calorimetric, were implemented in the IPR-R1 TRIGA nuclear research reactor at Belo Horizonte (Brazil) and are the focus of the work described here. Knowledge of the reactor thermal power is very important for precise neutron flux and fuel element burnup calculations. The burnup is linearly dependent on the reactor thermal power and its accuracy is important in the determination of the mass of burned 235U, fission products, fuel element activity, decay heat power generation and radiotoxicity. The thermal balance method developed in this project is now the standard methodology used for IPR-R1 TRIGA reactor power calibration and the fuel temperature measuring is the most reliable way of on-line monitoring of the reactor power. This research project primarily aims at increasing the reliability and safety of nuclear reactors using alternative methods for power monitoring.
SPRAY CONE ANGLES GENERATED BY A DUAL CENTRIFUGAL INJECTOR
Authors: Vásquez R. A. , Costa F. S.
Published: November 2018

A dual pressure swirl injector is characterized by two independent concentric chambers which can provide independent rotational levels to a single liquid or two different liquids. This paper compares theoretical, semi-empirical and experimental results concerning the spray cone angles formed by injection of water, ethanol and biodiesel through a dual pressure swirl injector. Data are obtained for injection of the same liquid through the primary and secondary chambers and for injection of ethanol in the primary chamber and biodiesel through the secondary chamber of the injector. Experimental data are obtained using photographic techniques and are analyzed by an image processing software developed in Matlab language.
EVALUATION OF PRESSURE DROP IN FLOW OVER FIXED POROUS BED
Authors: Cruz R. B. , Guerra D. R. S. , Azevedo T. L.
Published: November 2018

Many studies are conducted about the dynamics of fluids in porous media, which generates a number of factors and problems are solved. In particular the phenomenon of pressure drop in flows on fixed bed, although fairly well in the form Ergun’s equation, still has certain inconsistencies with regard to the types of materials to be used in the packaging of the beds. The objective of this work is to study this phenomenon using some experiments reported in the literature to determine the pressure drop in fixed bed consisting of porous particles of açaí seed. Experimental studies were conducted to predict, and take into account the losses resulting from friction and inertia that showed strong dependence on velocity. The method of using the particular friction factor prediction as a way to replace the usual calculation and measurement of pressure drop. The analysis in the wind tunnel was made from different sizes of bed, with a decrease in arithmetic progressions corresponding to half the value of the diameter of the tube used in the test. Several bands of Reynolds number were also employed in order to be able to visualize how the phenomenon behaves on various tracks. For such a survey was necessary some parameters such as açaí seeds diameters, seed weight and volume occupied by the bed; these parameters are of vital importance in Ergun equation, because an important aspect of the phenomenon is the porosity which enters as a foundation in the theory of flow fixed bed. At the end of the study was found the divergence in big bands of the Reynolds number of the correlation between experimental data and the Ergun equation.
PROTOTYPE OF A HEAT RECOVERY FOR COOLING OF GASES FROM INCINERATION OF HAZARDOUS WASTE
Authors: Costa R. C. , Martins M. A.
Published: November 2018

This paper presents the stages of development and construction of a prototype of a shell and tube heat recovery for reuse heat energy of the products generated by combustion of hazardous waste incinerator class I. The performance and energy recovered by this system were calculated. It was transported the values found for a typical plant for the incineration of 1,000 kg h-1. Thus, to preheat the combustion air and drying the waste was obtained a reduction in the consumption of LPG 46 and 45%, respectively. Considering the complexity of the process, it was found that the preheating system is simpler and can be deployed in a shorter time and lower cost when compared to a drying residue.
THERMODYNAMIC ANALYSIS AND ECOLOGICAL EFFICIENCY OF A COMBINED CYCLE POWER PLANT
Authors: Santos C. F. P. , Paulino R. F. S. , Tuna C. E. , Silveira J. L. , Araújo F. H. M.
Published: November 2018

The purpose of this article is to through the analysis of the first law of thermodynamic for a combined cycle determines the ecological coefficient of the same. This system consists of two gas turbines, two heat recovery boilers and a steam turbine, having a total installed capacity of power generation of 500 MW. This plant will be installed in a small town located 180 km from São Paulo. This place was chosen based on technical aspects by present proximity to the pipeline and transmission line, water availability and other favorable environmental aspects of the project. The natural gas that will serve as the plant's fuel will come from the Field of Mexilhão, from the base of Caraguatatuba, and the water used for cooling will come from the Paraíba do Sul River.