Relationship between Buchholz's Apparent Power and Instantaneous Power in Three-Phase Systems

[EN] Similarly to how Steinmetz developed his theory of alternating current in single-phase sinusoidal systems, a few formal relationships between expressions of the instantaneous and Buchholz's apparent power in three-phase systems were identified in this paper. Based on these relationships, a methodology to express Buchholz's apparent power and its components in any three-phase, wye-configured system-sinusoidal or non-sinusoidal, balanced or unbalanced-through instantaneous power expressions was established. The application of the proposed method to the entire system allowed the determination of a novel quantity referred to as neutral-displacement power, which measured the impacts of the phenomena caused by the neutral path operation on the values of the source and load apparent power. These impacts were analyzed using a real-world urban installation with a neutral conductor deterioration simulation via an Excel platform as an application example.This research was funded by the European Commission, grant number 847132. The APC was funded by the European Commission, grant number 847132. We gratefully thank Eléctrica de Vinalesa, S.L.U., for allowing us to take measurements using their electrical networks, and MDPI (www.mdpi.com/authors/english) for their English language editing. The authors deeply thank the European Commission for their support and funding provision.León-Martínez, V.; Montañana-Romeu, J.; Peñalvo-López, E.; Valencia-Salazar, I. (2020). Relationship between Buchholz's Apparent Power and Instantaneous Power in Three-Phase Systems. Applied Sciences. 10(5):1-15. https://doi.org/10.3390/app10051798S115105Czarnecki, L. S. (1987). What is wrong with the Budeanu concept of reactive and distortion power and why it should be abandoned. IEEE Transactions on Instrumentation and Measurement, IM-36(3), 834-837. doi:10.1109/tim.1987.6312797Czarnecki, L. S. (1988). Orthogonal decomposition of the currents in a 3-phase nonlinear asymmetrical circuit with a nonsinusoidal voltage source. IEEE Transactions on Instrumentation and Measurement, 37(1), 30-34. doi:10.1109/19.2658Czarnecki, L. S. (2008). Currents’ Physical Components (CPC) concept: A fundamental of power theory. 2008 International School on Nonsinusoidal Currents and Compensation. doi:10.1109/isncc.2008.4627483CZARNECKI, L. (2015). Currents’ Physical Components (CPC) in Three-Phase Systems with Asymmetrical Voltage. PRZEGLĄD ELEKTROTECHNICZNY, 1(6), 42-49. doi:10.15199/48.2015.06.06Emanuel, A. E. (1999). Apparent power definitions for three-phase systems. IEEE Transactions on Power Delivery, 14(3), 767-772. doi:10.1109/61.772313Pajic, S., & Emanuel, A. E. (2006). Modern Apparent Power Definitions: Theoretical Versus Practical Approach—The General Case. IEEE Transactions on Power Delivery, 21(4), 1787-1792. doi:10.1109/tpwrd.2006.876647Depenbrock, M. (1993). The FBD-method, a generally applicable tool for analyzing power relations. IEEE Transactions on Power Systems, 8(2), 381-387. doi:10.1109/59.260849Ferrero, A. (2007). Definitions of electrical quantities commonly used in non-sinusoidal conditions. European Transactions on Electrical Power, 8(4), 235-240. doi:10.1002/etep.4450080403Curtis, H. L., & Silsbee, F. B. (1935). Definitions of power and related quantities. Electrical Engineering, 54(4), 394-404. doi:10.1109/ee.1935.6539147Emanuel, A. E., & Orr, J. A. (s. f.). The effect of neutral path impedance on voltage and current distortion. Part I. symmetrical and balanced three-phase systems. 2004 11th International Conference on Harmonics and Quality of Power (IEEE Cat. No.04EX951). doi:10.1109/ichqp.2004.1409351Emanuel, A. E., & Orr, J. A. (s. f.). The effect of neutral path impedance on voltage and current distortion. Part II. Imbalanced three-phase systems. 2004 11th International Conference on Harmonics and Quality of Power (IEEE Cat. No.04EX951). doi:10.1109/ichqp.2004.1409350Blasco, P. A., Montoya-Mira, R., Diez, J. M., Montoya, R., & Reig, M. J. (2019). Compensation of Reactive Power and Unbalanced Power in Three-Phase Three-Wire Systems Connected to an Infinite Power Network. Applied Sciences, 10(1), 113. doi:10.3390/app10010113Akagi, H., Kanazawa, Y., & Nabae, A. (1984). Instantaneous Reactive Power Compensators Comprising Switching Devices without Energy Storage Components. IEEE Transactions on Industry Applications, IA-20(3), 625-630. doi:10.1109/tia.1984.4504460Czarnecki, L. S. (2006). Could Power Properties of Three-Phase Systems Be Described in Terms of the Poynting Vector? IEEE Transactions on Power Delivery, 21(1), 339-344. doi:10.1109/tpwrd.2005.852353Jeon, S. (2015). Properties of the generalised power theory: universality and partitioning/augmentation properties. IET Generation, Transmission & Distribution, 9(15), 2126-2134. doi:10.1049/iet-gtd.2014.0303Czarnecki, L. S. (2015). Critical comments on the Conservative Power Theory (CPT). 2015 International School on Nonsinusoidal Currents and Compensation (ISNCC). doi:10.1109/isncc.2015.7174713Artemenko, M. Y., & Batrak, L. M. (2017). The new formula for apparent power and power losses of three-phase four-wire system. 2017 IEEE 37th International Conference on Electronics and Nanotechnology (ELNANO). doi:10.1109/elnano.2017.793978

Study of the Improvement on Energy Efficiency for a Building in the Mediterranean Area by the Installation of a Green Roof System

[EN] Rooftop gardens ona building have proved to be a good way to improve its storm water management, but many other benefits can be obtained from the installation of these systems, such as reduction of energy consumption, decrease of the heat stress, abatement on CO2 emissions, etc. In this paper, the effect from the presence of these rooftop gardens on abuilding's energy consumption has been investigated by experimental campaigns using a green roof ona public building in a Mediterranean location in Spain. The obtained results demonstrate a substantial improvement by the installation of the green roof onthe building's cooling energy demand for a standard summer day, in the order of 30%, and a reduction, about 15%, in the heating energy demand for a winter day. Thus, given the longer duration of the summer conditions along the year, a noticeable reduction on energy demand could be obtained. Simulation analysis, using commercial software TRNSYS code, previously calibrated using experimental data for typical summer and winter days, allows for the extrapolation to the entire year of these results deducing noticeable improvement in energy efficiency, in the order of 19%, but with an increase of 6% in the peak power during the winter period.This work was supported by the European Union's Horizon 2020 research and innovation programme under the project Green Cities for Climate and Water Resilience, Sustainable Economic Growth, Healthy Citizens and Environments with reference 730283.Peñalvo-López, E.; Cárcel Carrasco, FJ.; Alfonso-Solar, D.; Valencia-Salazar, I.; Hurtado-Perez, E. (2020). Study of the Improvement on Energy Efficiency for a Building in the Mediterranean Area by the Installation of a Green Roof System. Energies. 13(5):1-14. https://doi.org/10.3390/en13051246S114135Jim, C. Y. (2017). Green roof evolution through exemplars: Germinal prototypes to modern variants. Sustainable Cities and Society, 35, 69-82. doi:10.1016/j.scs.2017.08.001Dos Santos, S. M., Silva, J. F. F., dos Santos, G. C., de Macedo, P. M. T., & Gavazza, S. (2019). Integrating conventional and green roofs for mitigating thermal discomfort and water scarcity in urban areas. Journal of Cleaner Production, 219, 639-648. doi:10.1016/j.jclepro.2019.01.068Ferrans, P., Rey, C., Pérez, G., Rodríguez, J., & Díaz-Granados, M. (2018). Effect of Green Roof Configuration and Hydrological Variables on Runoff Water Quantity and Quality. Water, 10(7), 960. doi:10.3390/w10070960Gómez, F., Valcuende, M., Matzarakis, A., & Cárcel, J. (2018). Design of natural elements in open spaces of cities with a Mediterranean climate, conditions for comfort and urban ecology. Environmental Science and Pollution Research, 25(26), 26643-26652. doi:10.1007/s11356-018-2736-1Chen, X., Shuai, C., Chen, Z., & Zhang, Y. (2019). What are the root causes hindering the implementation of green roofs in urban China? Science of The Total Environment, 654, 742-750. doi:10.1016/j.scitotenv.2018.11.051Radhi, H., Sharples, S., Taleb, H., & Fahmy, M. (2017). Will cool roofs improve the thermal performance of our built environment? A study assessing roof systems in Bahrain. Energy and Buildings, 135, 324-337. doi:10.1016/j.enbuild.2016.11.048Baik, J.-J., Kwak, K.-H., Park, S.-B., & Ryu, Y.-H. (2012). Effects of building roof greening on air quality in street canyons. Atmospheric Environment, 61, 48-55. doi:10.1016/j.atmosenv.2012.06.076Shafique, M., Kim, R., & Rafiq, M. (2018). Green roof benefits, opportunities and challenges – A review. Renewable and Sustainable Energy Reviews, 90, 757-773. doi:10.1016/j.rser.2018.04.006Goussous, J., Siam, H., & Alzoubi, H. (2015). Prospects of green roof technology for energy and thermal benefits in buildings: Case of Jordan. Sustainable Cities and Society, 14, 425-440. doi:10.1016/j.scs.2014.05.012Yang, W., Wang, Z., Cui, J., Zhu, Z., & Zhao, X. (2015). Comparative study of the thermal performance of the novel green (planting) roofs against other existing roofs. Sustainable Cities and Society, 16, 1-12. doi:10.1016/j.scs.2015.01.002Foustalieraki, M., Assimakopoulos, M. N., Santamouris, M., & Pangalou, H. (2017). Energy performance of a medium scale green roof system installed on a commercial building using numerical and experimental data recorded during the cold period of the year. Energy and Buildings, 135, 33-38. doi:10.1016/j.enbuild.2016.10.056Santamouris, M., Pavlou, C., Doukas, P., Mihalakakou, G., Synnefa, A., Hatzibiros, A., & Patargias, P. (2007). Investigating and analysing the energy and environmental performance of an experimental green roof system installed in a nursery school building in Athens, Greece. Energy, 32(9), 1781-1788. doi:10.1016/j.energy.2006.11.011Zhao, X., Zuo, J., Wu, G., & Huang, C. (2018). A bibliometric review of green building research 2000–2016. Architectural Science Review, 62(1), 74-88. doi:10.1080/00038628.2018.1485548Feng, C., Meng, Q., & Zhang, Y. (2010). Theoretical and experimental analysis of the energy balance of extensive green roofs. Energy and Buildings, 42(6), 959-965. doi:10.1016/j.enbuild.2009.12.014Tang, X., & Qu, M. (2016). Phase change and thermal performance analysis for green roofs in cold climates. Energy and Buildings, 121, 165-175. doi:10.1016/j.enbuild.2016.03.069Jim, C. Y., & Tsang, S. W. (2011). Ecological energetics of tropical intensive green roof. Energy and Buildings, 43(10), 2696-2704. doi:10.1016/j.enbuild.2011.06.018Bevilacqua, P., Mazzeo, D., Bruno, R., & Arcuri, N. (2016). Experimental investigation of the thermal performances of an extensive green roof in the Mediterranean area. Energy and Buildings, 122, 63-79. doi:10.1016/j.enbuild.2016.03.062Susca, T. (2019). Green roofs to reduce building energy use? A review on key structural factors of green roofs and their effects on urban climate. Building and Environment, 162, 106273. doi:10.1016/j.buildenv.2019.106273Ávila-Hernández, A., Simá, E., Xamán, J., Hernández-Pérez, I., Téllez-Velázquez, E., & Chagolla-Aranda, M. A. (2020). Test box experiment and simulations of a green-roof: Thermal and energy performance of a residential building standard for Mexico. Energy and Buildings, 209, 109709. doi:10.1016/j.enbuild.2019.109709Tian, Z., Lei, Y., & Gu, X. (2017). Building Energy Impacts of Simple Green Roofs in the Hot Summer and Cold Winter Climate Zone: Suzhou as a Study Case. Procedia Engineering, 205, 2918-2924. doi:10.1016/j.proeng.2017.10.095Coma, J., Pérez, G., Solé, C., Castell, A., & Cabeza, L. F. (2016). Thermal assessment of extensive green roofs as passive tool for energy savings in buildings. Renewable Energy, 85, 1106-1115. doi:10.1016/j.renene.2015.07.07

El COVID-19, la normativa de ventilación y su impacto ambiental en las universidades en México

[EN] This paper analyses the increase in energy consumption caused by COVID-19 containment measures in university classrooms in Mexico, particularly in hot humid areas where the use of air conditioning units is required. The effect of ventilation on classroom temperature, student comfort and air conditioning equipment consumption are analysed.Queremos agradecer a GENERALITAT VALENCIANA y a la Comisión Europea su apoyo en el marco del proyecto DECAB (NÚMERO de subvención GV/2021/149) y del proyecto H2020, SMEmPower (GA 847132).Valencia-Salazar, I.; Peñalvo-López, E.; Montañana-Romeu, J.; León-Martínez, V. (2021). El COVID-19, la normativa de ventilación y su impacto ambiental en las universidades en México. Área de Innovación y Desarrollo,S.L. 71-82. http://hdl.handle.net/10251/190680718

Competitive Risaralda, generating research alliance for development

El presente libro lleva como título “Risaralda competitiva, generando alianzas en investigación para el desarrollo”, resultado del V encuentro de investigadores del departamento de Risaralda realizado en el mes de noviembre del año 2020. Evento en el cual se presentaron las últimas investigaciones realizadas en las diferentes instituciones educativas del departamento; quienes hacen parte de la Mesa de Investigaciones de Risaralda; ejercicio de gran interés que arroja resultados de investigaciones en diferentes áreas como son las Ciencias Agrícolas, Ciencias sociales, Ciencias de la salud, Ciencias de la tecnología y la información

Ítacas: sentidos, territorios y experiencias investigativas en Comunicación Social.

El programa de Comunicación Social de UNIMINUTO produce nuevo conocimiento desde enfoques multidisciplinares en las líneas de Educación, transformación social e innovación; Desarrollo humano y comunicación; Innovaciones sociales y productivas; y Gestión social, participación y desarrollo comunitario, las cuales aportan y fortalecen el perfil profesional e investigador de docentes y estudiantes del programa. Los resultados de las reflexiones que realizan los profesores y estudiantes se plantean como ejercicios introspectivos desde la investigación en comunicación social. Esta publicación busca divulgar el trabajo investigativo de profesores y estudiantes, especialmente este primer número representa el inicio de un camino que esperamos derive en la formación posgradual en niveles superiores de nuestros investigadores y aporte a la comprensión de la comunicación digital en este mundo globalizado. Desde una perspectiva amplia de la producción académica, la investigación se entiende como una mixtura de enfoques (cualitativo y cuantitativo), incluyendo los emergentes, además de variadas estrategias de recolección de información que resultan coherentes con los intereses investigativos del programa y los objetivos propuestos en la ruta de fortalecimento académico, para la articulación adecuada entre la formación y el desarrollo de propuestas científicas. Es así como el grupo de investigación Comunicación, Convergencia y Desarrollo asume la responsabilidad de conducir cada proyecto de investigación propuesto, de acuerdo con los propósitos de formación y la amplia comprensión del campo de la comunicación

Ítacas: sentidos, territorios y experiencias investigativas en Comunicación Social.

El programa de Comunicación Social de UNIMINUTO produce nuevo conocimiento desde enfoques multidisciplinares en las líneas de Educación, transformación social e innovación; Desarrollo humano y comunicación; Innovaciones sociales y productivas; y Gestión social, participación y desarrollo comunitario, las cuales aportan y fortalecen el perfil profesional e investigador de docentes y estudiantes del programa. Los resultados de las reflexiones que realizan los profesores y estudiantes se plantean como ejercicios introspectivos desde la investigación en comunicación social. Esta publicación busca divulgar el trabajo investigativo de profesores y estudiantes, especialmente este primer número representa el inicio de un camino que esperamos derive en la formación posgradual en niveles superiores de nuestros investigadores y aporte a la comprensión de la comunicación digital en este mundo globalizado. Desde una perspectiva amplia de la producción académica, la investigación se entiende como una mixtura de enfoques (cualitativo y cuantitativo), incluyendo los emergentes, además de variadas estrategias de recolección de información que resultan coherentes con los intereses investigativos del programa y los objetivos propuestos en la ruta de fortalecimento académico, para la articulación adecuada entre la formación y el desarrollo de propuestas científicas. Es así como el grupo de investigación Comunicación, Convergencia y Desarrollo asume la responsabilidad de conducir cada proyecto de investigación propuesto, de acuerdo con los propósitos de formación y la amplia comprensión del campo de la comunicación

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat