bluuebunny/crossref_metadata_2025 huggingface dataset:
Reduction of pipe wall erosion by creating a vortex flow in anthracite powder pneumatic transport for power plants
Authors: Dorina Ionescu
Published: May 2017

From the total electricity generated in South Africa, about 85% is coal based. Coal powder is a solid fuel used in injectors for electricity production. The coal powder is extremely abrasive therefore it is important to maintain a minimum admissible flow speed. As the most severe pipe wall erosion takes place in bends, the most significant factor influencing wall erosion is the solid particle velocity. The aim of this research was to reduce the wall erosion through flow velocity control. Computational fluid dynamics (CFD) simulations, showed that for the same velocity, the erosion is dependent on flow direction change and the ratio between the radius of the bend and pipe diameter. The reduction of flow velocity was achieved by subtracting a spiral volume, from the inner volume of a horizontal pipe, just before an upward or downward bend. The modified volume geometry generated a vortex flow in the bend, achieving a more even distribution of maximum erosion points over the bend surface. The wall erosion, expressed in mm–wall thickness loss/hour, in the modified volume decreased by about 28,8 % while the installation life expectancy increased significantly. Furthermore the bend radius was proved to influence the erosion magnitude and location.
Voltage Dip Immunity of Equipment and Installations Messages to stakeholders
Authors: M. Bollen  , S. Cundeva  , R. Neumann  , J. Gordon  , S. Djokic  , K. n  , G. Ethier  , Hydro Quebec, Montreal, Canada
Published: May 2017

This paper presents the messages to the stakeholders on voltage-dip immunity as extracted by UIE WG2 from CIGRE TB412 [1]. The paper summarizes the main recommendations from this technical brochure in the form of messages towards regulators, standard-setting-organizations, network operators, industrial customers, equipment manufacturers, and power quality monitor manufacturers, researchers.
Development of Energy Saving Mechanism for Renewable Hydrogen Vehicles
Authors: K.K.T. Thanapalan  , F. Zhang  , A.D. Procter  , S.J.W. Carr  , G.C. Premier  , A.J. Guwy  , J. Maddy
Published: May 2017

This paper describes the development of energy saving mechanisms for renewable hydrogen vehicles, thereby providing extended range and improved efficiency. Simulation studies of configuration setup and analysis for better energy management strategies are carried out using simulation tools developed by the University of Glamorgan (UoG), Faculty of Advanced Technology (FAT). The simulation tools are used to analyze the effect of operating conditions and energy demand of a hybrid vehicle. A dynamic model of onboard hydrogen production employing electrolysis energized by electricity recovered from the vehicle’s suspension sub-system, is implemented in MATLAB/Simulink™ and integrated with a fuel cell vehicle model. The entire system model is then parameterized to represent a renewable hydrogen fuel cell vehicle for simulation analyses. Simulation results show that by using recovered energy normally lost in damping, appreciable benefits might be accrued from hydrogen production on-board.
Voltage Regulation in Low Voltage Distribution Networks with Embedded Photovoltaic Microgeneration
Authors: Marcelo Pais  , M.E. Almeida  , Rui Castro
Published: May 2017

Low voltage distribution networks have been originally designed to feed loads. However, recently, small dispersed renewable generators, mainly photovoltaics, are being connected to the low voltage grids. This new operational framework represents a challenge to the planning and operation of distribution networks, since the multidimensional stochastic dependence structure of the joint behaviour of the generation and load can be very complex to model. This paper intends to give further insight to the subject by presenting a three-phase unbalanced load flow method suitable to deal with radial networks with embedded microgeneration. Some results concerning the voltage profile as obtained after Monte-Carlo simulations for different load scenarios are presented in the paper, as well as an assessment of the generation shedding procedures undertaken to control the voltage.
Determination of the tracking system's trajectory considering the electric drive losses
Authors: S. Seme  , G. Štumberger
Published: May 2017

This paper deals with optimal sun-tracking of a photovoltaic system considering the electric drive losses. The Sun tracking photovoltaic system assures that the highest possible share of the available solar radiation reaches the surface of the photovoltaic modules. The electric drive which enables tracking is considered as the loss of the energy produced in the photovoltaic system. The maximum of the energy produced in the photovoltaic system is achieved by the continuous tracking of the photovoltaic system. Since the electric drives are determined by constant speed and time, and angle quantization the maximum of the energy produced can only approximate. The results presented in this paper show, that the optimal trajectories can help to increase the electrical energy production within photovoltaic systems by sun tracking.
Total integration of renewable and fossil energy aiming to a clean and sustainable energy system
Authors: D.G. Pinatti  , R.A. Conte
Published: May 2017

This paper presents a new concept of total integration of renewable and fossil energies (TIRFE), represented by an octagonal structure of all sources, vectors of transmission and optimization of consumption, aiming a clean and sustainable energy system. The main TIRFE technologies are: cogeneration of H2 and electric energy (EE) by biomass gasification in supercritical water integrated with a thermoelectric unit (H2 -BGSCW/TEU); use of H2 from biomass in oil refinery processes for production of light and clean derivatives; supply of H2 deficiency for methanol production from coal; carbon sequestration by a basket of technologies (exhausted P&G wells, underground saline aquifers, forests and stockpile of cellulignin-CL-produced from forest residues); use of H2 -BGSCW/TEU as district CHP with photovoltaic panels for EE, including electric car battery recharge; optimization of energy consumption by verticalization of the cities replacing low strength materials (bricks and common cement) by high performance concrete with addition of silica from rice husk. TIRFE helps to solve key problems of H2 -BGSCW/TEU, such as materials, energy recovery, plugging, corrosion, economics and energy security for the first generation of plants, and organizes the development for the second generation. TIRFE can be incrementally implanted in existent and new cities
Optimal Allocation of Mega-solar Power Station using Integrated Input and Output-oriented models in Data Envelopment Analysis
Authors: S. Yokota  , T. Kumano
Published: May 2017

In this paper, optimal allocation of mega-solar power station is studied using Data Envelopment Analysis (DEA). In Japan, A great attention is paid to natural energy. Especially, installation of a mega-solar station, which is a large photovoltaic power plant over 1MW, is beginning. In order to propose the optimal allocation, DEA method is applied in this research. Land cost, earthquake occurrence, transmission loss are used as inputs, and the amount of global solar radiation, and population density are used as outputs. The target locations are at 81 points in 5 prefectures of Chubu District in Japan. We perform ranking in consideration of input-oriented and output-oriented in BCC model, and successfully get solutions about the mega-solar optimal allocation.
Controllogger: A remote monitoring system for decentralized renewable energy sources
Authors: Fábio T. Brito  , Sandro C.S. Jucá  , Paulo C.M. Carvalho
Published: May 2017

The development of a remote monitoring and control system for decentralized renewable energy plants is described in the present paper. The system has a microcontroller-based unit for local storing and data transmission to internet by a GSM modem and a database server to store the data. The proposed architecture is easily extended for controlling a decentralized renewable energy plant by a remote operator. Correlations and performance tests are used to compare the data collected by the system prototype with data collected by a commercial data acquisition system. The results indicate that the Root Mean Square Error (RMSE) is 0.103 m/s for the wind speed measurement and the correlation factor is greater than 0.9996. Overall, the low errors rates indicate that the data have been stored in a similar form to what would be expected with the use of a commercial data logger.
An Approach to Decrease Transient Circulating Current of VSIs in Islanded Microgrid
Authors: M. Kohansal  , G. B. Gharehpetian  , M.Aghaei  , M. J. Sanjari
Published: May 2017

This paper investigates new methods of transient power sharing in parallel inverters. In order to obtain a faster transient response, a control unit is added to conventional droop method. In this control unit, the nominal frequency and voltage of inverters are changed to control the circulating current during transients. In this wireless method, the amount and period of circulating current between inverters are reduced. A detailed analysis shows that the proposed method has a superior transient performance and power sharing in comparison with the other methods. The simulation results indicate the accuracy of the proposed method.
A Simple Method for Detection of Voltage Sags and their Mitigation using a Dynamic Voltage Restorer
Authors: P.Meena  , K.Umarao  , Ravishankar Deekshit
Published: May 2017

Power quality is the major focus of progressive nations.In the era of smart grid,power quality receives a lot of thrust at all voltage levels namely,medium ,high and low.The objective of this paper is to present a simple and cost effective method of sag detection and mitigation in three phase systems at the consumer's end. The use of the concept of space vector representation of three phase quantities, effectively in the detection ,quantification and mitigation of short duration voltage disturbances such as sags in three phase supply systems under both balanced and unbalanced conditions of operation is presented.Three phase balanced quantities can be represented by a synchronously rotating space vector of constant magnitude .The two phase equivalent of which on a stationary reference frame are orthogonal to each other.When balanced sags occur,the magnitude of the rotating space vector obtained as a resultant of its orthogonal components is sensed for magnitude deviations from its constant nominal value.A trigger signal of varying amplitude is generated in proportional response to the detection of the deviation in its magnitude . In case of sags occurring on one or two phases of the supply, (unblanced),the positive sequence components of the unbalanced three phase quanities are determined using mathematical transformations and the magnitude of the resultant is found out. This resultant is sensed and its deviations from nominal value are measured and used to generate the trigger after processing.The trigger thus generated, initiates the control system of a Dynamic Voltage Restorer(DVR).When a sag is detected,the trigger signal generated, switches on the control circuit of the inverter which uses the space vector pwm control using sampled phase amplitudes of the control signal to generate the modulating wave in proportion to the deviation of the sag voltage from the reference value.The fundamental component of the output voltage which in proportion to the deviation from the nominal value is injected in series with the three phase disturbed signal through a transformer of suitable gain .The results show the successful operation of the DVR in maintaining nominal value of the voltage across the load through out the duration of the disturbance for all cases of balanced and unbalanced operation. The paper presents the detection algorithm as well as the control algorithm for restoration of voltage which are simple and easy to implement .
Implementation of a controller for a static VAr compensator in large industrial networks
Authors: Lj. Spasojević  , I. Papič  , B. Blažič
Published: May 2017

This paper deals with the development of a control algorithm for reactive-power compensation, flicker compensation and voltage regulation in large, industrial networks. The concept of compensation with a static-var compensator (SVC) and control-algorithm verification with realistic simulation examples using an actual industrial-network model are presented. In this paper a new control algorithm for control SVC devices is proposed. With this controller the SVC devices can operate in three modes: reactive-power compensation, flicker-level compensation or voltage regulation. The advantages of the proposed controller compared to other known regulators are the better flicker-level compensation and cheaper installation, because it requires only one measurement location. The data obtained with the simulations showed that the proposed controller can be successfully used for the control SVC devices for the reduction of flicker levels, the compensation of reactive power and for the regulation of voltage levels in large industrial networks.
Energetic sustainability of the building substitution: the rewards and the facilitations of the Italian Piano Casa
Authors: V. Sapienza  , A. Gagliano  , R. Chiaramonte
Published: May 2017

The residential building estate of a large part of the Italian cities is formed by poor quality buildings. In fact, until the last decades of the past century, the current standards were lower than the actual ones (with regards to the structural safety, the indoor comfort, the thermal plants, etc). Moving to the more suburban part of the city, it is possible to see how the high quality of the urban landscape of the city centre vanishes therefore the substitution of the buildings becomes more convenient than the refurbishment, as it is possible to obtain high standards in an easier way. To promote this type of actions, the Italian Government has introduced a group of regulations, called the “Piano Casa”. With the Piano Casa is possible to obtain an enlargement of the building volume during the reconstruction of residential buildings. The Sicilian Regional Government, with the adoption of these regulations in its jurisdiction, has introduced some further advantages which can be obtained using various topics of energy sustainability in the design. The authors, in the present work, have developed this subject through the cases of a multifunctional building.
Fluid Structure Interaction of a loaded Darrieus Marine Current Turbine
Authors: M. Belhache  , S. Guillou  , P. Grangeret  , A. Santa-Cruz  , F. Bellanger
Published: May 2017

The present study aims to develop a model to simulate in 2 dimensions, the motion of the fluid and of the loaded Darrieus turbine without imposing the rotational speed. A resistive torque has been added to account for the load of a generator. Experimental and numerical studies were conducted and presented here. The experiment was set-up in the air first, on a wind turbine for reason of convenience. The simulations were made with Fluent (v14) for which a User Defined Function was developed. Then the experimental conditions were reproduced numerically for three cases. The study focuses on the determination of a factor (f) giving the relationship between the experimental and the simulated resistive torque in 2 dimensions. The results are quite satisfying in this preliminary study as they demonstrate that the model developed works well. Some improvement has to be made to refine the value of f .
Oscillating rotary electrical machine for Stirling cycle heat pump and other devices of renewable energy
Authors: S. Kudarauskas  , J. Ulbikas  , T. Razvanovičius
Published: May 2017

The paper deals with oscillating rotary electrical machines, that is with periodical angular movement of their movable part. Expedient application of all oscillating electrical machines consists in possible avoidance of mechanical transformer in the drive, according to the direct drive principle. That is why oscillating electrical machines are suitable to use with positive displacement thermal machines. In the paper, principles of development of the Stirling cycle heat pump with oscillating rotary electrical motors according to the project EFFiHEAT are presented. Partners from Spain, Bulgaria and Lithuania are implementing the project. Tentative test of the oscillating rotary motor prototype confirms its working capacity and advantages. Principles of presented structure can be used in various other devices of renewable energy (e. g. solar power stations, geothermal power plants, heat and power cogenerators, generators with multi-fuel Stirling engine etc.).
Stability Analysis of Distributed Multi-Converter System
Authors: M. Zadeh  , M. Molinas
Published: May 2017

This paper discusses dynamic stability and performance of current control scheme for parallel connection of pulse-width modulated (PWM) voltage source converters (VSCs) fed by distributed energy recourses (DERs) across the distribution level of power grid. The controller has feedback compensation and limits the current harmonics while featuring fast regulation for multi-converter system. The controller enables islanded and grid-connected operations of DERs, dynamically. The load dynamics will be included in the stable control loop to provide perfect regulation of the voltage at the point of common coupling (PCC). The current controller is tested under the considerations of system delays. In the islanded mode, one of the controllable units provides voltage and frequency control as a master controller and the other units operate based on the grid-connected control strategy. The stability assessment of the system is presented based on a detailed simulation. The simulation results show that the controller for the islanded two-parallel controllable DER can ensure the stability of the system when converters are tied together. In the other hand, the weakness of the current control based method is drawn out while mismatch coupling condition.
Applicability Analysis of Single-Machine Equivalent Method for Modeling Wind Farm Containing Full-Converter Wind Turbine Generators with PMSG
Authors: Su Xunwen  , Xu Dianguo  , Bu Shupo  , Zheng Shuang
Published: May 2017

For the analysis of the applicability of single machine equivalent method for modeling wind farm containing full-converter wind turbine generators(WTG) with permanent magnet synchronous generator(PMSG), at frist, single-machine equivalent methods of equivalent model are provided, then the detailed and equivalent wind farm model is built on simulation software DIgSILENT/Power Factory platform. At last, for wind speed fluctuations and grid disturbance, the applicability of single-machine equivalent method is analyzed by comparing dynamic response at point of interconnection between equivalent model and the detailed model of wind farms. Results show that this method is suitable for the dynamic equivalent modeling of wind farm containing directly driven wind turbine with PMSG in certain situations.
Who pays for harmonic network losses caused by PV inverters?
Authors: J. Kiss  , A. Dán
Published: May 2017

The even growing number of small power (household rate) PV sets and the connecting inverters should warn utility companies to make a reconsideration on the network losses. Of course the main portion of the network losses is in connection with the fundamental current flow along the network. In our former papers [1], [2] and [3] it was pointed out that the harmonic network losses caused by non-linear loads generating harmonic currents actually are paid, because the non-linear loads receive as additional fundamental power the network losses originating by their generated harmonic currents. The PV inverter is a fundamental current power generator, but as a nonlinear element it generates harmonic currents as well. The fundamental current network loss cannot be separated into parts caused by consumption and generation; therefore the utility pays for the total energy supplied by the PV installation including the network loss. And what is the situation regarding the harmonic network loss? The paper gives a theoretical overview of the problem, furthermore – based on laboratory measurements – a proper computer simulation model was developed. Using computer simulations different practical scenarios are discussed.
Analysis of Importance of Components in Power Systems using Time Sequential Simulation
Authors: G. Vancells  , S. Herraiz  , J. Meléndez  , Á. Ferreira
Published: May 2017

Power systems reliability analysis consists in evaluating the ability of a system to perform its function without failures. Usually, it is measured in failures per year (λ). In the present work, the reliability of the global system is used to obtain the importance of components in order to identify which parts of the network must be improved or which components are the less reliable and need to be upgraded. The objective is to increase the global reliability of the system by introducing better components or redundant branches to guarantee the best quality of the power in the load points. A Time Sequential Monte Carlo simulation has been implemented in Matlab® and tested in a HV/MV substation to determine the importance of its components.
Medium-voltage distribution feeders in closed-loop arrangement – neutral point grounding
Authors: G. Štumberger  , K. Deželak  , M. Rošer  , R. Škof  , T. Kastelic
Published: May 2017

This paper deals with medium-voltage networks where the closed-loop arrangement of feeders is used to improve the reliability of power supply. The paper focuses on the neutral point grounding in the medium-voltage loops. They are established by closing feeders, supplied form different transformers, in closed-loop arrangement. It is shown in the case when the neutral points of transformers supplying the feeders are grounded, the fault current at the fault location can be doubled, without to influence the neutral point current, which could cause safety problems.
Power Flow Analysis of Distribution Systems with Large-Scale Wind and Conventional Energy Generation
Authors: A. González  , A. Madrazo  , R. Robles  , R. Domingo  , M. Mañana  , A. Arroyo  , M.A. Cavia
Published: May 2017

This paper is devoted to the development of a methodology suitable to be used to determine the impact of the grid integration of wind farms in distribution networks that are also supplied with other classical generation facilities based on thermal and hydraulic energy. The methodology is based on an automated analysis system that varies the level of the electric generation for both the hydraulic and thermal generators by using PSS, Phyton and Matlab. The user can define multiple scenarios considering wind, thermal and hydraulic generators so the line capacity can be computed and compared in order to know where the systembottleneck is located and which situations occur. All the results computed can be analysed in a single or compared way by using tables and plots and considering the static rate of the distribution lines. The developed system can also be applied to the computation of the sensitivity of the power flow to the variation of the parameters that define the power system.
Increasing Grid Integration of Wind Energy by using Ampacity Techniques
Authors: A. Madrazo  , A. González  , R. Martínez  , M. Mañana  , E. Hervás  , A. Arroyo  , P.B. Castro  , D. Silió
Published: May 2017

The grid integration of renewable energy, particularly in Spain, supposes an important problem to deal with for Distributor System Operators (DSO). Most of the times Wind Energy Farms are located in places that are far away from the transmission networks so they have to be integrated into distribution networks that are frequently operating close to their static rate. Current regulations make almost impossible to build new overhead lines so the increase of the capacity of the existing lines is a new target for the DSO. This paper is devoted to the analysis of a new methodology and monitoring system that have been developed to overcome the existing static rates by moving the operation point of the overhead lines close to their dynamic rate. This new rate is computed by using both the IEEE and CIGRÉ algorithms and a local weather forecast. The obtained results show that this approach can increase the capacity of the lines in a significant percentage.
Harmonic Distortion Index for Stationary and Transient States
Authors: M.-D. Borrás  , A. López  , J.-C. Bravo  , C. Alés  , J.-C. Montaño
Published: May 2017

For transient or aperiodic signals the Fourier analysis is unable to obtain accurate results and a joint time frequency analysis must be used to provide simultaneous time and frequency information of transient intervals. A power quality index is proposed for evaluation of both the stationary and transient quality aspects of electrical signals. The widely used total harmonic distortion index (THD) is redefined in this paper to include harmonics, oscillatory transients, voltage sags and swells. The new index is defined between the 0-1 range.
Case study of energy efficiency and electric power quality
Authors: C. Oliveira  , F. Sato  , E. Ruppert  , M. Kubo
Published: May 2017

This paper describes the results of the electrical energy efficiency and power quality evaluation done in the School of Electrical and Computer Engineering of the University of Campinas (Unicamp) in São Paulo State, Brazil, through the Project named Ecogera. The analysis was based on the electrical signals acquired in the switchgear of the Students Classroom Building of the School of Electrical and Computer Engineering using measurement and energy management instruments. The replacement of the old lightning system using 40 W old fashion fluorescent bulbs mounted on non reflective fixtures by new energy save 32W fluorescent bulbs mounted on reflective fixtures reduced expressively the electrical energy consumption and the installation electrical power demand. The measurements allowed to know the details of harmonic distortions and disturbances that affect voltage magnitude and current.
Computational Assessment of Control Strategy for PMSG Wind Turbines aiming at Voltage Regulation on Connection Point
Authors: A. Reis  , L. N. Velasco  , J. C. Oliveira
Published: May 2017

The growing deployment of wind energy conversion systems experienced in recent years has been reflected in increasing requirements for connection of such complexes to electric networks. In this way, in a near future, wind farms could be required to behave as conventional power plants, which, besides the characteristics of energy supply, promote support to the electrical system in steady state and transient conditions. In this context, this work is focused in a computational assessment of a control strategy directed to wind energy conversion system with permanent magnet synchronous generator (PMSG) aiming to regulate the voltage at the Point of Common Coupling. Therefore, after the mathematical description of the main physical components of such generating units, it proceeds to the computational implementation and performance evaluation of the control method using the ATP-EMTP simulator.
Design of Reactive Power Compensation Devices on the Base of Dynamical Simulation of Steelmaking Process
Authors: A. Novitskiy  , I. Konotop  , D. Westermann
Published: May 2017

Alternative current electric arc furnaces (AC-EAF) are characterized by significant active and reactive power consumption. The operation of electric arc furnaces can cause considerable harmonic distortion and voltage fluctuations (flicker) in the electric power system due to the non-linearity of electric arc and stochastic character of arc burning. The distortion level caused by AC EAF operation depends on the stage of the steelmaking process. The novel method of design of reactive power compensation devices on the base of dynamical digital simulation of complete steelmaking process is described in the offered paper.
Guide Vanes for Darrieus Water Turbine in Tidal Current
Authors: Koju Hiraki  , Kohei Nishida  , Ryo Wakita  , Manabu Takao  , Toshiaki Watanabe
Published: May 2017

On purpose to enhance the performance of a Darrieus-type water turbine for the power generation using a tidal current, the technique with guide vanes were applied. The guide vanes placed in front of the turbine, were expected to allow the turbine to rotate with higher speed by turning the direction of the current partially. The device was tested in both the wind and water tunnels, and its effect was recognized at both tests. Since the configuration with the twin turbines in parallel was considered advantageous especially under the weaker tidal current, the guide vanes suitable for the twin-turbine configuration were investigated using the wind tunnel, based on the previous results obtained in the single-turbine configuration. The experimental results showed that the guide vanes placed on the center line increased the rotational speed in the regions of lower tip-speed ratio.
Reduction of Zero Sequence Components in Three-Phase Transformerless Multiterminal DC-link based on Voltage Source Converters
Authors: M. Nieves-Portana  , M. Barragán-Villarejo  , J.M. Maza-Ortega  , J.M. Mauricio-Ferramola
Published: May 2017

This paper is focused on the analysis and reduction of zero sequence currents which appear in multiterminal DC links based on Voltage Source Converters (VSCs). A zero sequence current may flow between the VSCs due to the absence of the coupling transformer, in spite of this application is intended for three-phase three-wire system. The proposed solutions to mitigate this issue have been tested through simulation and experimental results.
Limit Cycle Oscillation Analysis on the Design of Wind Power Harvester with Fluttering Aerofoil
Authors: C. P. Pagwiwoko
Published: May 2017

This paper presents a new concept of wind power harvester which extracts the energy from the flow through an aeroelastic vibration phenomenon. Different from traditional rotating wind turbines, a fluttering aerofoil in the form of transversal and rotational motions is used in the process. Analysis of flutter characteristics in frequency domain is carried out to determine the flutter stability boundary. The energy is extracted at the wind speed above the flutter boundary where the system may become nonlinear. The operating range of the device is set up at a stabilized oscillation in the nonlinear zone by regulating the pitching motion limited to a certain angular travelling distance.
Efficiency Comparison of Grid Side Converters for DC Distribution Systems
Authors: M. C. Di Piazza  , G. Vitale
Published: May 2017

This paper aims to study the energy losses in Grid Side Converters (GSCs) used for grid connection of DC residential distribution systems, including renewables and storage. Two different electrical architectures have been considered, the former using an H-bridge as GSC and the latter a PFC active rectifier in association with a storage system. An observation time of one year has been fixed. The analysis is based on the same amount of energy generated by renewables and load demand, in both cases. A detailed formulation of the power losses in each component of the power converter is given. A comparison of the energy lost yearly in both the GSCs is presented, considering different sizing of the storage system.
Strategic Quality Control Measures to Reduce Defects in Composite Wind Turbine Blades
Authors: U.I.K. Galappaththi  , A.M. De Silva  , Milos Draskovic  , M Macdonald
Published: May 2017

Wind turbine blades are made from polymer composites to provide high specific stiffness, strength, and good fatigue performance. However, large composite structures are prone to manufacturing defects such as delamination and adhesive failure, which can lead to crack initiation and propagation under cyclic stresses. National renewable energy laboratory, USA statistics shows 26% fatigue failure modes are created by laminate and adhesive joint manufacturing errors. A range of manufacturing processes are used to construct wind turbine blades. Resin transfer infusion is one of the most frequently used methods in wind turbine blade manufacturing industry. This paper provides assessment on regular defects occurring in resin transfer infusion processes which lead to poor quality in wind turbine blade manufacture. The assessment is based on the existing literature and the know-how generated from manufacturing wind turbine blades. The effect of these defects for the structural failure of composite wind turbine blades is analysed. The final phase of the study provides manufacturing quality control measures which can be implemented to improve the composite wind turbine blade manufacturing process.
Design and Deployment of the Askaryan Radio Array South Pole Autonomous Renewable Power Stations (AARPS)
Authors: D. Z. Besson  , D. M. Kennedy  , K. Ratzlaff  , R. Young
Published: May 2017

Research was initiated in 2009 to determine the feasibility of constructing 300W autonomous renewable energy power stations at the South Pole. In January 2011, a test power station was constructed at the South Pole using three small scale wind turbines that included a system health monitor, meteorology and power instruments and remote communications pipeline. Significant testing and development was performed to prepare the hardware and electronics for the sub -40C environment. During December 2011, additional wind turbines and equipment were deployed at the South Pole to upgrade existing systems and perform additional testing. Results of field testing are presented.
DGFACTS comparative in wind power to solve LVRT requirements
Authors: M. Gómez-Pérez  , E. Jiménez-Macías  , E. Martínez-Cámara  , J.Ramos-Hernanz
Published: May 2017

This article compares the results recorded in the connection of three types of DGFACTS (DSTATCOM, DVR, UPQC) to a wind farm equipped with wind turbines with squirrel-cage induction generators, in order to test the response to voltage dips due to single-phase short circuit and two phase short circuit, because this type of asymmetric faults is one of the most common to consider a power system. The results are compared with a previous work, dealing with symmetric (three phase) short circuits. For illustrative purposes, reference has been made to a standard wind farm in Spain, which has been subject to a fault of the type specified in Operating Procedure 12.3 in the Spanish Grid Code. The aforementioned options provide the wind farms with LVRT capability, in addition to catering for numerous other possibilities that have not been considered within this research.
Expectativas com a carreira docente: escolha e inserção profissional de estudantes de Pedagogia
Authors: Ostrovski Crizieli , De Sousa Cintia , Raitz Tânia
Published: May 2017

Estudos dos processos de inserção profissional têm recebido um incremento nos últimos anos do século 21, favorecendo a aparição de um importante corpo teórico e investigador ao redor desse constructo. Universidades, pesquisadores, educadores e orientadores profissionais vêm acumulando experiências e uma vasta produção acerca do tema engendrado por inquietações e pela busca de alternativas para o tratamento da inserção socioprofissional. O artigo analisa as expectativas dos acadêmicos de um curso de licenciatura em Pedagogia, de uma universidade comunitária no sul do País, quanto à escolha profissional e à inserção no mercado de trabalho. Apresenta uma pesquisa de abordagem qualitativa, e como instrumento de coleta dos dados apoiou-se em um questionário semiestruturado, com perguntas abertas e fechadas, aplicado a um grupo representativo de formandos do curso de Pedagogia. Os dados foram tratados por meio da análise de conteúdo. Os resultados evidenciaram o reconhecimento da escolha profissional dos acadêmicos, identificando suas expectativas positivas quanto à inserção no mercado de trabalho na respectiva área. Algumas informações revelaram pontos negativos em relação ao pouco reconhecimento social da carreira e à baixa remuneração. Nesse sentido, a análise considera uma teia de relações vivenciadas pelos formandos durante esse percurso.
A religiosidade na prática docente
Authors: Valente Gabriela
Published: May 2017

O artigo apresenta resultados de uma pesquisa sobre a presença da religiosidade na escola pública. Em um estudo de inspiração etnográfica, acompanharam-se duas salas de ensino fundamental I em um município de São Paulo, e foi possível observar que, diferentemente do que se imaginava, a religião não está presente na escola de maneira explícita, mas de forma oculta e difusa, como uma forte influência na prática docente das professoras e ferindo o princípio de laicidade do Estado. O texto se inicia com uma breve exposição dos pressupostos teóricos na área da sociologia da educação, segue com a exposição da prática docente de duas professoras e se consolida com a análise das formas de religiosidade presentes na instituição escolar.
Multiplicidades de resoluções de alunos do ensino médio em problemas abertos de matemática
Authors: Dalto Jader , Dos Santos João Ricardo , De Buriasco Regina Luzia
Published: May 2017

Investigam-se maneiras de lidar de alunos da educação básica com problemas abertos de matemática. Para isso, seis problemas abertos de matemática foram aplicados em duas turmas do 9º ano do ensino fundamental e duas turmas do 3º ano do ensino médio de uma escola pública. Por meio de uma abordagem qualitativa de pesquisa, analisou-se a multiplicidade das resoluções dos alunos e evidenciaram-se suas singularidades. A análise mostrou uma variedade de estratégias apresentadas pelos alunos ao resolverem os problemas. Essas estratégias são muito singulares, elaboradas por modos idiossincráticos de os alunos lerem o enunciado do problema, implementarem uma maneira de lidar com ele e construírem um processo de resolução. Diante dessas singularidades, foi identificada uma multiplicidade de resoluções, diversos e diferentes modos de resolução dos problemas. Ao resolverem problemas abertos, a atividade matemática dos alunos se dá por meio de processos que são, muitas vezes, pouco observados pelos professores. Nessa direção, a análise da produção escrita mostra-se como possibilidade de olhar para as maneiras de lidar dos alunos, de modo a não caracterizá-los pela falta, pontuando o que não foi feito ou aquilo que deveria ter sido feito.
Editorial
Authors: Científica Editoria
Published: May 2017

Neste número da Revista Brasileira de Estudos Pedagógicos (RBEP) brindamos o leitor com uma seleção principal de artigos cujos temas abordam as políticas educacionais e o cotidiano escolar, a formação docente para a educação básica, a docência e a expectativa estudantil na educação superior, práticas pedagógicas no conhecimento escolar da Matemática e da Língua Portuguesa e letramentos culturais no ensino de Língua Portuguesa. Outros assuntos tratados nos artigos são as diferentes perspectivas teórico-metodológicas dos programas de mentoria, o ensino de religião e a prática docente. Fecham o número um relato de experiência, ligando trajetória de estudantes das classes populares e acesso à educação superior, e a resenha de uma obra que relaciona pedagogia, epistemologia e poesia.
Buenas prácticas ganaderas en hatos lecheros de Santa Rosa de Cabal, Risaralda, Colombia
Authors: Marín A Libia , Arredondo B Julia , Hernandez H Darwin
Published: May 2017

El objetivo del presente trabajo fue analizar el grado de cumplimiento de BPG, mediante la evaluación de 99 variables en 21 sistemas productivos del municipio de Santa Rosa de Cabal, Risaralda. Solo uno de los predios cumplió con los 48 criterios fundamentales exigidos y en general, el grado de cumplimiento de criterios mayores y menores fue insuficiente. Solo 8 de los hatos están certificados como libres de brucelosis y tuberculosis. Las áreas de mejor desempeño son el bienestar animal (81%) y las relacionadas con la rutina de ordeño (79,1%); en cambio, las mas deficientes fueron el control de medicamentos veterinarios e insumos agropecuarios (5,8%), así como las condiciones del tanque de enfriamiento (32,6%). Mediante un Análisis de Correspondencia múltiple, se encontró asociación significativa entre variables que tienen que ver con la garantía en la inocuidad de la leche, en lo referente a la operación, limpieza y desinfección de equipos que garanticen una temperatura adecuada. También hubo asociación entre variables que tienen que ver con el procedimiento de ordeño y condiciones de higiene durante la faena, que involucran tanto al operario, como al animal. Se evidencia falta de capacitación y concientización acerca de la importancia del cumplimiento de muchos criterios de BPG, que es una herramienta fundamental para obtener un diagnostico del estado actual del hato, y en la cual posiblemente sea necesario tener en cuenta otras variables, no incluidas en la lista de verificación actual, para una posterior implementación y seguimiento a planes de mejoramiento de los sistemas productivos.
Comportamiento sexual de novillas Brahman en el trópico bajo mediante control farmacológico del estro
Authors: González T Marco , Escobar C Clara , Reyes Silvia
Published: May 2017

Se utilizaron 33 novillas Brahman, con edades y pesos similares y se  conformaron tres grupos para evaluar el comportamiento sexual mediante control farmacológico del estro.  A cada grupo se le asignó al azar uno de los siguientes tratamientos: Grupo control, conformado por nueve novillas (G1); día cero: implante subcutáneo en la cara externa de la oreja con 3 mg de norgestomet, más inyección muscular de 3 mg de norgestomet y 5 mg de valerato de estradiol. Día siete: inyección muscular de 0,15 mg de (D+) cloprostenol. Día nueve: retiro del implante. Grupo dos (G2), igual que G1, pero en el día nueve se introdujeron 3 novillas en celo. Grupo tres (G3), igual que G1, pero el día nueve se introdujeron 3 novillas en anestro. Las novillas se observaron por 96 horas continuas. Los datos se recolectaron por el método de “Registro de secuencias”. La información se  analizó mediante estadística descriptiva y se compararon los grupos para establecer diferencias. El 100% de las novillas expresaron signos de celo y su inicio no se vio alterado con la inclusión de novillas en celo o en anestro. Después de retirado el implante, el inicio de celos para G1 fue a las 29.5 ± 4.8 h; para G2 a las 26.1 ± 4.7 h y para G3 a las 26.36 ± 4.6 horas. La duración del celo para los grupos en el mismo orden fue de 13. 6 ± 9.1 h; 12.7 ± 6.5 h y 18.7 ± 4.7 horas. El mayor porcentaje de celos y número de conductas sexuales se alcanzó entre las 30-34 horas post-retiro de los implantes (G1: 100%; G2:88.8%; G3: 100%). La inclusión de novillas el día nueve del protocolo no alteró la iniciación o retardo de la presentación de celos.
Actividad antimicrobiana de bacterias endófitas aisladas de orégano serrano (Lippia origanoides) contra Burkholderia glumae y Colletotrichum gloeosporioides
Authors: Arrieta D Lorena , Chamorro A Leonardo , Montes V Donicer
Published: May 2017

El objetivo de éste estudio fue determinar la diversidad de bacterias endófitas asociadas a la especie vegetal Lippia origanoides de la subregión sabanas en el Departamento de Sucre, Colombia y evaluar su actividad antimicrobiana contra Colletotrichum gloeosporioides y Burkholderia glumae. Se utilizó la técnica de desinfección superficial de tejidos y el aislamiento se realizó en medio de cultivo agar R2A. La densidad poblacional (UFC/g de tejido) se estimó por conteo directo de colonias en placa. Las significancias estadísticas entre densidad poblacional, con relación a tejidos y sitio, se realizó mediante análisis multifactorial y prueba múltiple de rango (Tukey). Las bacterias endófitas que presentaron inhibición contra los microorganismos patógenos fueron sometidas a un proceso de extracción de metabolitos secundarios. La prueba antimicrobiana, antifúngica y de metabolitos secundarios se llevaron a cabo mediante ensayos de confrontación y estimación cualitativa. Los resultados muestran que existe una densidad poblacional de bacterias endófitas asociadas a plantas de orégano serrano y la abundancia está relacionada con el tejido. Ninguno de los morfotipos presentó actividad antimicrobiana para B. glumae. Uno de los morfotipos tuvo actividad antifúngica frente a C. gloeosporioides y se le realizó extracción de metabolitos para determinar la actividad antifúngica a partir de suspensiones celulares.
Compensación forestal del sistema estratégico de transporte de pasajeros (SETP) de Sincelejo - Colombia
Authors: Vergara F Vicente , Pretelt B Viviana
Published: May 2017

En este estudio se realizó una evaluación de las compensaciones forestales realizadas en el marco del proyecto de implementación del Sistema Estratégico de Transporte de Pasajeros (SETP) del Municipio de Sincelejo – Colombia, con la finalidad de obtener un referente de eficiencia de estas. Inicialmente se recolectó la información secundaría representada en las resoluciones de permisos de aprovechamiento forestales y los informes de cumplimiento de las mencionadas resoluciones. Esa información permitió identificar el número de plantas y los lugares donde fueron sembradas. Posteriormente fueron inventariados los árboles existentes productos de las compensaciones forestales enmarcadas en el proyecto tomado como referencia del estudio y se estimó el volumen aprovechable total de los mismos, obteniéndose como resultado 8,07 m3. Este dato fue calculado de un total 1.141 especies a partir de medidas de altura aprovechable (Altura fuste) y Diámetro a Altura de Pecho (DAP). En función de la cantidad de árboles existentes se concluyó como positivo el impacto generado por las compensaciones forestales evaluadas, en cuanto a la producción de biomasa y captura de CO2.
Pseudomonas aeruginosa productora de metabolito con actividad antimicrobiana contra Burkholderia glumae
Authors: Barraza R Zafiro , Bravo J Ana , Pérez-Cordero Alexander
Published: May 2017

El presente estudio tuvo como objetivo evaluar in vitro la actividad antimicrobiana de bacterias endófitas asociadas a Neem (Azadirachta indica) contra la bacteria fitopatógena Burkholderia glumae. La actividad inhibitoria de bacterias endófitas contra B. glumae se evaluó por antagonismo, mediante la técnica de difusión en agar con discos sensitivos. Una vez identificadas las bacterias endófitas con potencial inhibitorio, se empleó medio número 3 para producción de metabolitos secundarios, para probar su inhibición contra B. glumae mediante la técnica de microdilucion en placas de Elisa. Los resultados mostraron, una inhibición del 50% del crecimiento de B. glumae por parte de la bacteria endófita asilada. La identificación de la bacteria endófita con potencial inhibitorio contra B. glumae se realizó por medio un kit API 20 NE, donde el perfil de identificación arrojo un 99,5% para Pseudomonas aeruginosa.