12 research outputs found
Enhancing Power Quality with PDO-FOPID Controller in Unified Power Quality Conditioner for Grid-Connected Hybrid Renewables
Full text linkAddressing the pressing research problem of power fluctuations and grid harmonics in the integration of renewable energy, our proposed control strategy utilizes the Prairie Dog Optimization Fractional Order Proportional Integral Derivative (PDO-FOPID) controller within a Unified Power Quality Conditioner (UPQC) system. This innovative approach is tailored to mitigate harmonics and meet load requirements in grid-connected hybrid renewables. The UPQC system is instrumental in regulating coupling point voltage, countering voltage and current harmonics to enhance overall power quality. The PDO-FOPID controller dynamically adapts control parameters to system dynamics and load changes, ensuring a stable power supply despite the variability of renewable sources. Simulations in MATLAB/Simulink confirm its superiority over traditional control strategies, such as PI, sliding mode, and fuzzy control, in harmonics mitigation, load fulfilment, and power stability. By effectively addressing these challenges, our proposed solution not only contributes to resolving a critical research problem but also advances the seamless integration of Hybrid Renewable Energy Sources (HRES) into power systems, thereby enhancing overall grid performance and the efficacy of renewable energy integration.
Experimental procedure for the characterization of turbocharger s waste-gate discharge coefficient
Full text link[EN] Nowadays, the turbocharger has become one of the key components for automotive spark-ignition engine
improvements (fed with both liquid and gaseous fuels), as a support for the boosting and downsizing concept to reduce
fuel consumption and exhaust emission. In gasoline engines, the usage of the waste-gate valve typically regulates the
maximum boost pressure in the turbocharger system, to protect the engine and the turbocharger at high engine speeds.
To improve the transient response at low engine speeds two-stage turbocharger is widely used. Two-stage systems are
composed of several valves to regulate the flow to control the boosting of the system. Like, a by-pass valve between the
turbines, a check valve between the compressor and a waste-gate valve for the low-pressure turbines. This paper deals
with a methodology for characterizing the discharge coefficient of an electronic waste-gate valve in the turbocharger. To
estimate the gas flow over the same in one-dimensional models, an empirical model is correlated and validated. For this,
a constant stream experimental work has been carried out on a test rig at different valve position openings, with high
turbine inlet temperatures. Finally, an optimal MAP of discharge coefficient has been drawn out through interpolation
method, which can integrate into the full one-dimensional turbocharged engine model system, to calculate the actual
mass flow through the waste-gate valve.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was partially funded by FEDER and Government of Spain through Project TRA2016-79185-R.Serrano, J.; Arnau Martínez, FJ.; Tiseira ., AO.; Samala, V. (2017). Experimental procedure for the characterization of turbocharger s waste-gate discharge coefficient. Advances in Mechanical Engineering. 9(10):1-9. https://doi.org/10.1177/1687814017728242S1991
A holistic methodology to correct heat transfer and bearing friction losses from hot turbocharger maps in order to obtain adiabatic efficiency of the turbomachinery
Full text linkThis is the author¿s version of a work that was accepted for publication in International Journal of Engine Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting,
and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published as https://doi.org/10.1177/1468087419834194[EN] Turbocharger performance maps provided by manufacturers are usually far from the assumption of reproducing the isentropic
performance. The reason being, those maps are usually measured using a hot gas stand. The definition of the
effective turbocharger efficiency maps include the mechanical losses and heat transfer that has occurred during the gas
stand test for the turbine maps and only the heat transfer for the compressor maps. Thus, a turbocharger engine model
that uses these maps provides accurate results only when simulating turbocharger operative conditions similar to those
at which the maps are recorded. However, for some critical situations such as Worldwide harmonized Light vehicles
Test Cycles (WLTC) driving cycle or off-design conditions, it is difficult to ensure this assumption. In this article, an internal
and external heat transfer model combined with mechanical losses model, both previously developed and calibrated, has
been used as an original tool to ascertain a calculation procedure to obtain adiabatic maps from diabatic standard turbocharger
maps. The turbocharger working operative conditions at the time of map measurements and geometrical information
of the turbocharger are necessary to discount both effects precisely. However, the maps from turbocharger manufacturers
do not include all required information. These create additional challenges to develop the procedure to obtain approximated
adiabatic maps making some assumptions based on SAE standards for non-available data. A sensitivity study has been
included in this article to check the validity of the hypothesis proposed by changing the values of parameters which are not
included in the map data. The proposed procedure becomes a valuable tool either for Original Equipment Manufacturers
(OEMs) to parameterize turbocharger performance accurately for benchmarking and turbocharged engine design or to turbocharger
manufacturers to provide much-appreciated information of their performance maps.The author(s) disclosed receipt of the following financial support for the research, authorship and/or publication of this article: This work has been partially
supported by FEDER and the Government of Spain
through Grant No. TRA2016-79185-R.Serrano, J.; Olmeda, P.; Arnau Martínez, FJ.; Samala, V. (2020). A holistic methodology to correct heat transfer and bearing friction losses from hot turbocharger maps in order to obtain adiabatic efficiency of the turbomachinery. International Journal of Engine Research. 21(8):1314-1335. https://doi.org/10.1177/1468087419834194S13141335218Sirakov, B., & Casey, M. (2012). Evaluation of Heat Transfer Effects on Turbocharger Performance. Journal of Turbomachinery, 135(2). doi:10.1115/1.4006608Payri, F., Serrano, J. R., Fajardo, P., Reyes-Belmonte, M. A., & Gozalbo-Belles, R. (2012). A physically based methodology to extrapolate performance maps of radial turbines. Energy Conversion and Management, 55, 149-163. doi:10.1016/j.enconman.2011.11.003Chesse, P., Chalet, D., & Tauzia, X. (2011). Impact of the Heat Transfer on the Performance Calculations of Automotive Turbocharger Compressor. Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles, 66(5), 791-800. doi:10.2516/ogst/2011129Serrano, J. R., Olmeda, P., Arnau, F. J., Reyes-Belmonte, M. A., & Tartoussi, H. (2015). A study on the internal convection in small turbochargers. Proposal of heat transfer convective coefficients. Applied Thermal Engineering, 89, 587-599. doi:10.1016/j.applthermaleng.2015.06.053Tanda, G., Marelli, S., Marmorato, G., & Capobianco, M. (2017). An experimental investigation of internal heat transfer in an automotive turbocharger compressor. Applied Energy, 193, 531-539. doi:10.1016/j.apenergy.2017.02.053Serrano, J., Olmeda, P., Arnau, F., & Dombrovsky, A. (2014). General Procedure for the Determination of Heat Transfer Properties in Small Automotive Turbochargers. SAE International Journal of Engines, 8(1), 30-41. doi:10.4271/2014-01-2857Payri, F., Olmeda, P., Arnau, F. J., Dombrovsky, A., & Smith, L. (2014). External heat losses in small turbochargers: Model and experiments. Energy, 71, 534-546. doi:10.1016/j.energy.2014.04.096Serrano, J. R., Olmeda, P., Tiseira, A., García-Cuevas, L. M., & Lefebvre, A. (2013). Theoretical and experimental study of mechanical losses in automotive turbochargers. Energy, 55, 888-898. doi:10.1016/j.energy.2013.04.042SAE International. Turbocharger gas stand test code, SAE J1826. Technical Report, Society of Automotive Engineers Inc, Warrendale, PA, 1995.SAE International. Supercharger testing standard, SAE J1723. Technical Report, Society of Automotive Engineers Inc, Warrendale, PA, 1995.Serrano, J. R., Olmeda, P., Páez, A., & Vidal, F. (2010). An experimental procedure to determine heat transfer properties of turbochargers. Measurement Science and Technology, 21(3), 035109. doi:10.1088/0957-0233/21/3/03510
Analyzing User Participation Across Different Answering Ranges in an Online Learning Community
Full text linkabstract: Online learning communities have changed the way users learn due to the technological affordances web 2.0 has offered. This shift has produced different kinds of learning communities like massive open online courses (MOOCs), learning management systems (LMS) and question and answer based learning communities. Question and answer based communities are an important part of social information seeking. Thousands of users participate in question and answer based communities on the web like Stack Overflow, Yahoo Answers and Wiki Answers. Research in user participation in different online communities identifies a universal phenomenon that a few users are responsible for answering a high percentage of questions and thus promoting the sustenance of a learning community. This principle implies two major categories of user participation, people who ask questions and those who answer questions. In this research, I try to look beyond this traditional view, identify multiple subtler user participation categories. Identification of multiple categories of users helps to provide specific support by treating each of these groups of users separately, in order to maintain the sustenance of the community.
In this thesis, participation behavior of users in an open and learning based question and answer community called OpenStudy has been analyzed. Initially, users were grouped into different categories based on the number of questions they have answered like non participators, sample participators, low, medium and high participators. In further steps, users were compared across several features which reflect temporal, content and question/thread specific dimensions of user participation including those suggestive of learning in OpenStudy.
The goal of this thesis is to analyze user participation in three steps:
a. Inter group participation analysis: compare pre assumed user groups across the participation features extracted from OpenStudy data.
b. Intra group participation analysis: Identify sub groups in each category and examine how participation differs within each group with help of unsupervised learning techniques.
c. With these grouping insights, suggest what interventions might support the categories of users for the benefit of users and community.
This thesis presents new insights into participation because of the broad range of
features extracted and their significance in understanding the behavior of users in this learning community.Dissertation/ThesisMasters Thesis Computer Science 201
Implementing Mindfulness-Based Stress Reduction for Nurses: A Quality Improvement Project
No full textAbstractPurpose of Project: The purpose of the project was to implement a brief mindfulness-based stress reduction (MBSR) protocol before the start of the shift to reduce acute care nurses’ stress levels and increase resilience.
Methodology: For 4 weeks, MBSR was introduced in the shift huddles. The nurses were guided through various therapeutic techniques and listened to positive affirmations. The sample was composed of 40 acute care nurses in total. Before and after the program, the nurses were assessed on their stress and coping skills using the Perceived Stress Scale (PSS) and Brief Resiliency Scale (BRS).
Results: The results of the PSS and BRS showed that MBSR caused a significant increase in stress reduction and resilience, While the average PSS pretest score was 18.13 (moderate stress), the average posttest score was 13.18 (low stress). The nurses’ resilience increased as well, with the average BRS score increasing from 3.57 to 3.88.
Implications for Practice: The nurses who participated in the project intend to continue implementing mindfulness during huddle to be more relaxed and resilient to stress. This project shows the potential of mindfulness as a cost-effective, easily accessible, and sustainable way to reduce stress and anxiety.
Keywords: mindfulness-based stress reduction, nurses, stress, anxiety, resilience, patient care.D.N.P.Includes bibliographical referencesIncludes vit
Penerapan Metode Bermain Bowling Aritmatika Untuk Meningkatkan Kemampuan Kognitif Melalui Mengenal Angka 1-20 Pada Anak Kelompok B di TK Kristen Lembon Samala Moronge Selatan 1
No full textThis study aims to improve cognitive abilities through recognizing numbers 1-20. The method used is the arithmetic bowling method, all children are given the opportunity to play this game. To obtain data in this research the author uses the Class Action Research (CAR) method. This type of research uses the Kemmis and Mc. Taggart quoted Aqip Zainal (2006:31) which consists of 4 stages, namely: 1. Planning, 2. Implementation, 3. Observation, 4. Reflection. In the first cycle of research, it has not yet achieved complete learning, only getting a percentage of 61.1%. And in the second cycle of research, the percentage of children’s achievement increased by 33.3%. So the level of achievement of the percentage of children from cycle I to cycle II increased to 94.4%. In this research, there is still 1 child who has not yet achieved complete learning, so the researcher does remedial action on the child so that he no longer continues in the next cycle of research. Thus, from the results obtained, it means that the purpose of this research has been declared successful. Based on the results of research and discussion, it can be concluded that the method of applying bowling arithmetic through recognizing numbers 1-20 can improve students’ cognitive and learning outcomes. Thus the use of the method of applying arithmetic bowling is proven to be able to improve children’s cognitive abilities through recognizing numbers
Metaverse Technologies in Education: A Systematic Literature Review Using PRISMA
Full text linkMetaverse technology is emerging as a global trend, offering virtual activities with real-world experiences. This paper presents a systematic review of research trends from 2012–2022 to determine the prevalence and current conditions of metaverse technology in education. The PRISMA framework (selected reporting items for systematic review and meta-analysis) guided this systematic review. 42 studies were selected from the Scopus database, with more than 70 studies or references from Google Scholar kept as supporting data after quality assessment. The results indicate that research interest in metaverse technology has significantly increased in the last ten years, peaking in 2022. Augmentation and simulation are the most prominent uses of metaverse technology in the learning process. C. Moro (2017) is the most cited author on this topic, with 313 citations, followed by P. Wang (2022) with 264 citations and P. Pelargos (2022) with 163 citations. AR and VR are the most widely used types of metaverse technology. Hopefully, this review will be useful for researchers, educators, and future research on the metaverse and education
Global Publication Trends in Augmented Reality and Virtual Reality for Learning: The Last Twenty-One Years
Full text linkAugmented reality (AR) and virtual reality (VR) provide new experiences in the digital and simulation worlds. While they are intended to stimulate users’ perception and senses in general, the two differ significantly. This study aimed to seek and analyze international publications on the trends, similarities, differences, advantages, and disadvantages of AR and VR for learning over the period 2001-2021. In this study, bibliometric analysis using VOSViewer with the help of MS Excel was utilized to visualize metadata obtained from Scopus. Publish or Perish software supported the data collection of this study, which included retrieving and analyzing academic citations. The findings show that the AR/VR has trend continued to rise over the years. The results showed that Denmark and India (based on country bibliographic pairs), Journal of Physics Conference Series (based on journal bibliographic pairs), Y. Zhou publications (2018) (based on bibliographic pairs of publications), and Archana M. (India) with Lars K. (Denmark) (based on author bibliographic pairs) have become the most influential in the field of augmented reality and virtual reality for learning. AR and VR are two technologies changing how people use screens, thus creating new and exciting interactive experiences. In the future, it is expected that further research related to AR/VR and even Mixed Reality (MR) will continue to develop along with technological advancement. However, pedagogical competence remains an essential key to learning
Ant-Lion Optimization Algorithm Based Optimal Performance of Micro Grids
Full text linkIn the operational state of an electrical power system, ensuring efficient utilization and high-quality power usage is essential. Various quality enhancement measures, such as linear and adaptive filters, are implemented to improve the current's quality. Additionally, power flow controllers are employed to mitigate losses and enhance fault tolerance. However, the escalating demand for power supply, driven by rapid industrial and urban growth, often exceeds the capacity of existing generation systems. To address this challenge, supplementary subunits are integrated into the power system. This proposal's main objective is to introduce a weight-defined parameter monitoring system for power scheduling within a multi-parameter monitoring framework. The aim is to enhance the conventional preference-based scheduler by incorporating intelligent control techniques, including Unified Power Quality Conditioner (UPQC) with the ANT-LION Optimization (ALO) algorithm, which will be compared to a Fuzzy Logic controller. UPQC plays a pivotal role in addressing power quality issues within the system, combining a shunt active power filter with an Artificial Neural Network (ANN) controlled by the ALO algorithm. Our research demonstrates the effectiveness of this proposed system, particularly in microgrid applications, with validation conducted using MATLAB/Simulink.
Effects of ported shroud casing treatment on the acoustic and flow behaviour of a centrifugal compressor
Full text link[EN] Centrifugal turbomachines of smaller sizes operating at higher speeds have become pervasive due to the increased specific power and reliability achieved by improvements in manufacturing, materials and computational methods. The presence of these small turbomachines, specifically compressors, in helicopters, unmanned aerial vehicles (UAVs), auxiliary power units (APUs), turbochargers and micro gas turbines necessitates superior aerodynamic performance over a broad operational range which is widely achieved by ported shroud casing designs. In addition to aerodynamic performance, acoustic emissions have become a critical aspect of design for these small centrifugal compressors due to high operational speeds. Furthermore, the literature on the acoustic effects of the casing treatment is rather limited. Therefore, the impact of ported shroud casing treatment on the acoustic and flow features of the compressor operating at the design and near surge conditions have been quantified by numerically modelling the open and blocked configuration of the compressors. Upon comparing with experimental results, the numerical spectra are shown to capture the differences between the two configurations at the investigated operating points with reasonable accuracy. Although the casing treatment is generally seen to decrease the overall acoustic emission of the compressor at both operating conditions, increased propagation of tonal content in the direction upstream to the impeller is observed, particularly for design operation. Broadband characteristics in the lower and medium frequency regions usually associated with near surge operation including `whoosh' noise are observed to be alleviated by the ported shroud casing treatment.The author(s) disclosed receipt of the following financial support for the research, authorship and/or publication of this article: The project is sponsored and supported by BorgWarner Turbo Systems and the Regional Growth Fund (RGF Grant Award 01.09.07.01/1789C).Sharma, S.; Garcia Tiscar, J.; Allport, JM.; Barrans, S.; Nickson, AK. (2020). Effects of ported shroud casing treatment on the acoustic and flow behaviour of a centrifugal compressor. International Journal of Engine Research. 21(6):998-1011. https://doi.org/10.1177/1468087419880431S9981011216Fisher, F. B. (1988). Application of Map Width Enhancement Devices to Turbocharger Compressor Stages. SAE Technical Paper Series. doi:10.4271/880794Cheng, L., Dimitriou, P., Wang, W., Peng, J., & Aitouche, A. (2018). A novel fuzzy logic variable geometry turbocharger and exhaust gas recirculation control scheme for optimizing the performance and emissions of a diesel engine. International Journal of Engine Research, 21(8), 1298-1313. doi:10.1177/1468087418809261Teng, C., & Homco, S. (2009). Investigation of Compressor Whoosh Noise in Automotive Turbochargers. SAE International Journal of Passenger Cars - Mechanical Systems, 2(1), 1345-1351. doi:10.4271/2009-01-2053Figurella, N., Dehner, R., Selamet, A., Tallio, K., Miazgowicz, K., & Wade, R. (2014). Noise at the mid to high flow range of a turbocharger compressor. Noise Control Engineering Journal, 62(5), 306-312. doi:10.3397/1/376229Raitor, T., & Neise, W. (2008). Sound generation in centrifugal compressors. Journal of Sound and Vibration, 314(3-5), 738-756. doi:10.1016/j.jsv.2008.01.034Tiikoja, H., Rämmal, H., Abom, M., & Boden, H. (2011). Investigations of Automotive Turbocharger Acoustics. SAE International Journal of Engines, 4(2), 2531-2542. doi:10.4271/2011-24-0221Sharma, S., Broatch, A., García-Tíscar, J., Allport, J. M., & Nickson, A. K. (2018). Acoustic characteristics of a ported shroud turbocompressor operating at design conditions. International Journal of Engine Research, 21(8), 1454-1468. doi:10.1177/1468087418814635Broatch, A., Galindo, J., Navarro, R., & García-Tíscar, J. (2014). Methodology for experimental validation of a CFD model for predicting noise generation in centrifugal compressors. International Journal of Heat and Fluid Flow, 50, 134-144. doi:10.1016/j.ijheatfluidflow.2014.06.006Broatch, A., García-Tíscar, J., Roig, F., & Sharma, S. (2019). Dynamic mode decomposition of the acoustic field in radial compressors. Aerospace Science and Technology, 90, 388-400. doi:10.1016/j.ast.2019.05.015Sundström, E., Semlitsch, B., & Mihăescu, M. (2017). Generation Mechanisms of Rotating Stall and Surge in Centrifugal Compressors. Flow, Turbulence and Combustion, 100(3), 705-719. doi:10.1007/s10494-017-9877-zSundström, E., Semlitsch, B., & Mihăescu, M. (2018). Acoustic signature of flow instabilities in radial compressors. Journal of Sound and Vibration, 434, 221-236. doi:10.1016/j.jsv.2018.07.040Chen, H., & Lei, V.-M. (2013). Casing Treatment and Inlet Swirl of Centrifugal Compressors. Journal of Turbomachinery, 135(4). doi:10.1115/1.4007739Dehner, R. D., Selamet, A., Steiger, M., Miazgowicz, K., & Karim, A. (2017). The Effect of Ported Shroud Recirculating Casing Treatment on Turbocharger Centrifugal Compressor Acoustics. SAE International Journal of Engines, 10(4), 2057-2066. doi:10.4271/2017-01-1796Song, K., Zhao, B., Sun, H., & Yi, W. (2018). A physics-based zero-dimensional model for the mass flow rate of a turbocharger compressor with uniform/distorted inlet condition. International Journal of Engine Research, 20(6), 624-639. doi:10.1177/1468087418773673Broatch, A., Margot, X., García-Tíscar, J., & Roig, F. (2018). Impact of simple surge-enhancing inlet geometries on the acoustic behavior of a turbocompressor. International Journal of Engine Research, 21(5), 794-800. doi:10.1177/1468087418784125Galindo, J., Navarro, R., García-Cuevas, L. M., Tarí, D., Tartoussi, H., & Guilain, S. (2018). A zonal approach for estimating pressure ratio at compressor extreme off-design conditions. International Journal of Engine Research, 20(4), 393-404. doi:10.1177/1468087418754899Sharma, S., Broatch, A., García-Tíscar, J., Allport, J. M., & Nickson, A. K. (2019). Acoustic characterisation of a small high-speed centrifugal compressor with casing treatment: An experimental study. Aerospace Science and Technology, 95, 105518. doi:10.1016/j.ast.2019.105518Menter, F. (2018). Stress-Blended Eddy Simulation (SBES)—A New Paradigm in Hybrid RANS-LES Modeling. Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 27-37. doi:10.1007/978-3-319-70031-1_3Serrano, J. R., Olmeda, P., Arnau, F. J., & Samala, V. (2019). A holistic methodology to correct heat transfer and bearing friction losses from hot turbocharger maps in order to obtain adiabatic efficiency of the turbomachinery. International Journal of Engine Research, 21(8), 1314-1335. doi:10.1177/1468087419834194Gil, A., Tiseira, A. O., García-Cuevas, L. M., Usaquén, T. R., & Mijotte, G. (2018). Fast three-dimensional heat transfer model for computing internal temperatures in the bearing housing of automotive turbochargers. International Journal of Engine Research, 21(8), 1286-1297. doi:10.1177/1468087418804949Sharma, S., Broatch, A., García-Tíscar, J., Nickson, A. K., & Allport, J. M. (2019). Acoustic and pressure characteristics of a ported shroud turbocompressor operating at near surge conditions. Applied Acoustics, 148, 434-447. doi:10.1016/j.apacoust.2019.01.005Herwig, H., & Schmandt, B. (2014). How to Determine Losses in a Flow Field: A Paradigm Shift towards the Second Law Analysis. Entropy, 16(6), 2959-2989. doi:10.3390/e1606295
