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Mesalazine solubility in supercritical carbon dioxide with and without cosolvent and modeling
(Nature Research, 0025-12) Sajadian, Seyed Ali; Esfandiari, Nadia; Rojas, Adrián; Hemmati, Salar; Jouyban, Abolghasem; Aguila, Gonzalo; Garlapati, Chandrasekhar
In this study, the solubility of mesalazine in supercritical carbon dioxide with and without cosolvent was carried out for the first time at different temperatures and pressure values ranging from 308 to 338 K and 12 to 30 MPa, respectively. The determined experimental molar solubilities of mesalazine in supercritical carbon dioxide were in the range of 4.41 × 10–5 to 9.97 × 10–5 (308 K), 3.9 × 10–5 to 13.1 × 10–5 (318 K), 3.4 × 10–5 to 16 × 10–5 (328 K) and 3.3 × 10–5 to 18.4 × 10–5 (338 K). Meanwhile, the determined experimental molar solubilities in supercritical carbon dioxide using 2% dimethyl sulfoxide as cosolvent were in the range of 28.22 × 10–5 to 36.2 × 10–5 (308 K), 26.07 × 10–5 to 51.41 × 10–5 (318 K), 25.02 × 10–5 to 69.07 × 10–5 (328 K) and 25.86 × 10–5 to 82.6 × 10–5 (338 K). A novel association model was employed to simulate the solubility data of the binary and ternary systems. Various semiempirical correlations were utilized to calculate the solubility of mesalazine in supercritical carbon dioxide. The new association model was deemed the most superior model, achieving an average absolute relative deviation value of 4.13% without a cosolvent, and 3.36% when a cosolvent was included. © The Author(s) 2025.
Using implementation science to develop and deploy an oncology electronic health record
(Elsevier Ltd, 2025-01) Taramasco, Carla; Noel, Rene; Márquez, Gastón; Robles, Diego
The management of oncology clinical processes involves the efficient management of data using electronic clinical records to effectively monitor and treat oncology patients. As the process of treating and monitoring cancer patients involves multiple stakeholders with differing perspectives, the implementation and deployment of oncology clinical registries represent a significant challenge. In this study, we address this complexity by employing a technique that helps translate implementation strategies into requirement identification methods, which are subsequently disseminated throughout the implementation and deployment phases of health information systems. We applied this technique to develop an electronic health record for the national cancer plan in Chile. The findings indicate that six implementation strategies are essential to addressing stakeholder needs, as well as three requirement identification techniques to describe the underlying problem. Furthermore, a study conducted with 27 stakeholders revealed that the perception of the oncology electronic clinical record has considerable acceptance in three critical functionalities related to the clinical process of oncology patient management. The use of implementation science strategies provides an alternative approach to understanding the underlying problem that stakeholders face when they require healthcare technologies.
Adaptation and combination of two scales to measure dispositional gratitude in health sciences faculty: a psychometric analysi
(BioMed Central Ltd, 2024-02) Beltran-Sanchez, Jesus Alfonso; Valle de la O, Adrian; Nava-Manzo, Josue Omar; Dominguez, Angeles
Background: The study of gratitude has been a trending subject in psychology and emerging in health sciences education. For the past several years, interest has been aroused through various published contributions that still lack scientific support, so it is necessary to have instruments that obtain valid and reliable data about it. Gratitude has proven to be sensitive to different cultures. This research aims to determine the psychometric properties using a combined scale to measure dispositional gratitude in health sciences faculty. Method: A quantitative study was conducted with a non-experimental trans-sectional design with a correlational scope, with a sample of 216 professors of health sciences in a northeastern Mexico private university divided into subsamples for an Exploratory Factor Analysis (n = 113) and a Confirmatory Factor Analysis (n = 103). The Gratitude Questionnaire, Work Questionnaire and Brief Interactive Optimism-Garcia was applied to 110 women, 104 men and 2 who prefer not to specify their gender. Results: The result was a unifactorial measurement model composed of 10 items with evidence of construct validity (χ2 = 59.83, df = 20, p < 0.001, χ2/df = 59.83/20 = 2.99, SRMR = 0.11, GFI = 0.96; NFI = 0.93, RFI = 0.91, AGFI = 0.93), PRATIO = 0.78, PNFI = 0.73; concurrent validity with interactive optimism (r = 0.45, p < 0.001); convergent validity (AVE = 0.42); and reliability (α = 0.88; ω = 0.88). Conclusions: This model measures dispositional gratitude in health sciences Mexican faculty and contributes a vital instrument to advance future educational innovations involving this construct. The validation of the one-factor model with convergent reliability and validity suggests that the total scale score serves as an adequate measure of gratitude. Finally, it represents a valuable contribution to the teaching of health sciences since it generates healthy environments with prosocial attitudes that facilitate flourishing in personal and academic life, and in the future, health professionals with humanism as their standard
Mathematics classroom explanation: a literature review
(HISIN (History of Information Systems), 0025-01) Valdes, Gabriel
Research on explanation in the teaching of mathematics at the secondary education level is crucial for improving understanding and the effective learning of mathematical concepts. This study focuses on analyzing empirical research that has addressed the explanation in the teaching of mathematics at the secondary level, published in the last five years in journals indexed in the Web of Science. Methodology: A systematic analysis is carried out, following the PRISMA methodology to ensure a systematic and reproducible analysis. Results: The findings highlight that research at the primary and secondary educational levels on mathematical explanation is scarce. Studies with teaching innovations predominate. Discussions: The need for ongoing training for teachers is discussed, emphasizing the importance of clear explanations tailored to the needs of the students to facilitate deep and enduring learning, as well as the practical implications of the study. Conclusions: This study underscores the opportunity to expand research in this field to enrich pedagogical practices and improve the teaching of mathematics at fundamental educational levels. © 2025, HISIN (History of Information Systems). All rights reserved.
Phenomenographic analysis and comparison of students' conceptual understanding of electric and magnetic fields and the principle of superposition
(American Physical Society, 2021-12) Campos, Esmeralda; Hernandez, Eder; Barniol, Pablo; Zavala, Genaro
There are studies of students' understanding of the concept of the electric field, the magnetic field, and the use of the superposition principle that have contributed to the creation of both educational strategies and assessment tools. However, the difficulties of these two concepts have not been compared comprehensively. Therefore, this study aims to compare students' conceptual understanding of electric and magnetic fields in questions regarding the field created by one source and the field produced by a system of two sources. We focus our study on students' explanations about the magnitude and direction of the field and their application of the superposition principle in both contexts (electric and magnetic). We conducted this study with 322 engineering students in a Mexican university. We designed two versions of an open-ended questionnaire, one with the context of electricity and the other with magnetism. We created the questions using the parallelism between electricity and magnetism and used schematic representations with similar surface features to represent this parallelism. Analyzing the data through a phenomenographic approach, the students' drawings and explanations gave insight into their understanding of the concept of field and the superposition principle application in the context of electricity and magnetism. We found that students have similar categories of understanding the concept of the electric and the magnetic field. In both contexts, there is an evident relationship between applying the principle of superposition and understanding the concept of field. We found that there is a greater tendency that a student correctly applies the superposition principle if that student has a robust representation of the field. We found evidence that students consistently merge two different representations (vector plots and field lines) in electricity and magnetism. We named this category of representation "hybrid vectors and field lines."We also found that some students who draw hybrid representations of the field can still apply the superposition principle correctly. However, some conceptual understanding difficulties are dependent on the context: the known difficulty of confusion between forces and fields is more attached to the electricity context. The confusion between electricity and magnetism concepts is more relevant in the magnetism context. As in other literature, we found more evidence that the correct answer in multiple-choice questions may lead students who have mild difficulties (such as memorization and creating a hybrid representation) to choose a correct answer. We recommend that teachers and researchers of electricity and magnetism acknowledge the relationship between the conceptual understanding of the field and applying the superposition principle. We suggest that instructors be attentive to how they approach using representations of electric and magnetic fields. © 2021 authors. Published by the American Physical Society.
Development of computational approaches with a fragment-based drug design strategy: In silico hsp90 inhibitors discovery
(MDPI, 2021-12-02) León, Roberto; Soto-Delgado, Jorge; Montero, Elizabeth; Vargas, Matías
A semi-exhaustive approach and a heuristic search algorithm use a fragment-based drug design (FBDD) strategy for designing new inhibitors in an in silico process. A deconstruction reconstruction process uses a set of known Hsp90 ligands for generating new ones. The deconstruction process consists of cutting off a known ligand in fragments. The reconstruction process consists of coupling fragments to develop a new set of ligands. For evaluating the approaches, we compare the binding energy of the new ligands with the known ligands. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).
Distributed Control Scheme for Clusters of Power Quality Compensators in Grid-Tied AC Microgrids
(Multidisciplinary Digital Publishing Institute (MDPI), 2023-11) Martínez-Gómez, Manuel; Burgos-Mellado, Claudio; Morales-Paredes, Helmo Kelis; Gómez, Juan Sebastián; Verma, Anant Kumar; Bonaldo, Jakson Paulo
Modern electrical systems are required to provide increasing standards of power quality, so converters in microgrids need to cooperate to accomplish the requirements efficiently in terms of costs and energy. Currently, power quality compensators (PQCs) are deployed individually, with no capacity to support distant nodes. Motivated by this, this paper proposes a consensus-based scheme, augmented by the conservative power theory (CPT), for controlling clusters of PQCs aiming to improve the imbalance, harmonics and the power factor at multiple nodes of a grid-tied AC microgrid. The CPT calculates the current components that need to be compensated at the point of common coupling (PCC) and local nodes; then, compensations are implemented by using each grid-following converter’s remaining volt-ampere capacity, converting them in PQCs and improving the system’s efficiency. The proposal yields the non-active power balancing among PQCs compounding a cluster. Constraints of cumulative non-active contribution and maximum disposable power are included in each controller. Also, grid-support components are calculated locally based on shared information from the PCC. Extensive simulations show a seamless compensation (even with time delays) of unbalanced and harmonics current (below 20% each) at selected buses, with control convergences of 0.5–1.5 [s] within clusters and 1.0–3.0 [s] for multi-cluster cooperation. © 2023 by the authors.
Evaluation of Machine Learning Techniques for Classifying and Balancing Data on an Unbalanced Mini-Mental State Examination Test Data Collection Applied in Chile
(Institute of Electrical and Electronics Engineers Inc., 2024) Ormeno, Pablo; Marquez, Gaston; Taramasco, Carla
The Mini-Mental State Examination (MMSE) is the most widely used cognitive test for assessing whether suspected symptoms align with cognitive impairment or dementia. The results of this test are meaningful for clinicians but exhibit highly unbalanced distributions in studies and analyses regarding the classification of patients with cognitive impairment. This is a complex problem when a large number of MMSE tests are analysed. Therefore, data balancing and classification techniques are crucial to support decision-making in distinguishing patients with cognitive impairment in an effective and efficient manner. This study explores machine learning techniques for data balancing and classification using a real unbalanced dataset consisting of MMSE test responses collected from 103 elderly patients participating in a Chilean patient monitoring project. We used 8 data classification techniques and five data balancing techniques. We evaluated the performance of the techniques using the following metrics: sensitivity, specificity, F1-score, likelihood ratio (LR+ and LR-), diagnostic odds ratio (DOR), and the area under the ROC curve (AUC). From the set of data balancing and classification techniques used in this study, the results indicate that synthetic minority oversampling and random forest balancing techniques improve the accuracy of cognitive impairment diagnosis. The results obtained in this study support clinical decision-making regarding early classification or exclusion of older adult patients with suspected cognitive impairment. © 2013 IEEE.
Relationship of Community Mobility, Vital Space, and Faller Status in Older Adults
(Multidisciplinary Digital Publishing Institute (MDPI), 0024-12) Robles Cruz, Diego; Lira Belmar, Andrea; Fleury, Anthony; Lam, Méline; Castro Andrade, Rossana M.; Puebla Quiñones, Sebastián; Taramasco Toro, Carla
Community mobility, encompassing both active (e.g., walking) and passive (e.g., driving) transport, plays a crucial role in maintaining autonomy and social interaction among older adults. This study aimed to quantify community mobility in older adults and explore the relationship between GPS- and accelerometer-derived metrics and fall risk. Methods: A total of 129 older adults, with and without a history of falls, were monitored over an 8 h period using GPS and accelerometer data. Three experimental conditions were evaluated: GPS data alone, accelerometer data alone, and a combination of both. Classification models, including Random Forest (RF), Support Vector Machines (SVMs), and K-Nearest Neighbors (KNN), were employed to classify participants based on their fall history. Results: For GPS data alone, RF achieved 74% accuracy, while SVM and KNN reached 67% and 62%, respectively. Using accelerometer data, RF achieved 95% accuracy, and both SVM and KNN achieved 90%. Combining GPS and accelerometer data improved model performance, with RF reaching 97% accuracy, SVM achieving 95%, and KNN 87%. Conclusion: The integration of GPS and accelerometer data significantly enhances the accuracy of distinguishing older adults with and without a history of falls. These findings highlight the potential of sensor-based approaches for accurate fall risk assessment in community-dwelling older adults. © 2024 by the authors.
Explicit Modeling of Brain State Duration Using Hidden Semi Markov Models in EEG Data
(Institute of Electrical and Electronics Engineers Inc., 2024) Trujillo-Barreto, Nelson J.; Galvez, David Araya; Astudillo, Aland; El-Deredy, Wael
We consider the detection and characterization of brain state transitions based on ongoing electroencephalography (EEG). Here, a brain state represents a specific brain dynamical regime or mode of operation that produces a characteristic quasi-stable pattern of activity at the topography, sources, or network levels. These states and their transitions over time can reflect fundamental computational properties of the brain, shaping human behavior and brain function. The hidden Markov model (HMM) has emerged as a useful tool for uncovering the hidden dynamics of brain state transitions based on observed data. However, the limitations of the Geometric distribution of states' durations (dwell times) implicit in the standard HMM, make it sub-optimal for modeling brain states in EEG. We propose using hidden semi Markov models (HSMM), a generalization of HMM that allows modeling the brain states duration distributions explicitly. We present a Bayesian formulation of HSMM and use the variational Bayes framework to efficiently estimate the HSMM parameters, the number of brain states, and select among candidate brain state duration distributions. We assess HSMM performance against HMM on simulated data and demonstrate that the accurate modeling of state durations is paramount for making reliable inference when the task at hand requires accurate model predictions. Finally, we use actual resting-state EEG data to illustrate the benefits of the approach in practice. We demonstrate that the possibility of modeling brain state durations explicitly provides a new way for investigating the nature of the neural dynamics that generated the EEG data. © 2013 IEEE.
Modeling and Solving the Time-Dependent in-Building Delivery Problem in Last-Mile Logistics
(Institute of Electrical and Electronics Engineers Inc., 2024) Paredes-Belmar, Germán; Latorre-Núñez, Guillermo; Bronfman, Andrés
This article introduces, models, and solves the time-dependent in-building delivery problem in last-mile logistics. It determines efficient travel sequences for a worker (e.g., delivery person, deliveryman, mailman, agent) who delivers goods or provides services directly to customers located within a building using its elevation system. We study, in detail, all the steps involved in a travel sequence inside a building: horizontal trips, unloading products to the customers, waiting for elevators, and vertical trips within elevators. The sequences and their total times vary depending on the building type, the elevation system, the moment of the day, and the arrival time because of the daily building traffic intensity variations. A mixed-integer linear programming model and a genetic algorithm-based metaheuristic are proposed to solve a set of instances in two office buildings. The results show that it is very important to determine the best time to visit a building because of its time dependency. The variation in delivery time between off-peak hours versus peak hours is between 15% and 30% for the set of solved instances. Moreover, the order of customer visits differs drastically depending on the arrival time to the building. © 2013 IEEE.
Harnessing evolutionary algorithms for enhanced characterization of ENSO events
(Springer, 0025-01) Abdulkarimova, Ulviya; Abarca-del-Rio, Rodrigo; Collet, Pierre
The El Niño-Southern Oscillation (ENSO) significantly influences the complexity and variability of the global climate system, driving its variability. ENSO events’ irregularity and unpredictability arise from intricate ocean–atmosphere interactions and nonlinear feedback mechanisms, complicating their prediction of timing, intensity, and geographic impacts. This study applies Genetic Programming and Genetic Algorithms within the EASEA (EAsy Specification of Evolutionary Algorithms) Evolutionary Algorithms (EA) framework to develop a repository of symbolic equations for El Niño and La Niña events, spanning their various intensities. By analyzing data from the Oceanic Niño Index, this approach yields equation-based characterizations of ENSO events. This methodology not only enhances ENSO characterization strategies but also contributes to expanding the use of EAs in climate event analysis. The resulting equations have the potential to offer insights beyond academia, benefiting education, climate policy, and environmental management. This highlights the importance of ongoing refinement, validation, and exploration in these fields through EAs. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.
Model Sets with Euclidean internal Space
(Cambridge University Press, 0022-11-07) Allendes Cerda, Mauricio; Coronel, Daniel
We give a characterization of inter-model sets with Euclidean internal space. This characterization is similar to previous results for general inter-model sets obtained independently by Baake, Lenz and Moody, and Aujogue. The new ingredients are two additional conditions. The first condition is on the rank of the abelian group generated by the set of internal differences. The second condition is on a flow on a torus defined via the address map introduced by Lagarias. This flow plays the role of the maximal equicontinuous factor in the previous characterizations. © The Author(s), 2023. Published by Cambridge University Press.
Statistical Analysis to Quantify the Impact of Map Type on Estimating Peak Discharge in Non-Instrumented Basins
(Universidad Tecnologica de Bolivar, 0023-08-11) Sierra-Sánchez, Alexandra; Gatica, Gustavo; Paternina-Verona, Duban A; Ramos, Helena M.
The calculation of peak discharge in non-instrumented basins requires including morphometric parameters, which in turn depend on the map type used. This study analyses the impact of and variation in peak discharges of the Caño Ricaurte basin, Colombia, based on three types of maps at different resolution scales. The reference map used was the map made for the detailed designs of the channel analysed, which was extracted from the Master Plan of the City. Additionally, maps from a 90 × 90 m digital elevation model and contour lines extracted from Google Earth were used. The time of concentration was determined by different equations (Kirpich, Témez, Bureau, and TR-55) using the mapping methods described above, and the peak discharge was determined using rainfall-runoff models. © 2023 by the authors.
Improving and measuring the solubility of favipiravir and montelukast in SC-CO2 with ethanol projecting their nanonization
(Royal Society of Chemistry, 2023-11) Rojas, Adrián; Sajadian, Seyed Ali; López-De-Dicastillo, Carol; Ardestani, Nedasadat Saadati; Aguila, Gonzalo; Jouyban, Abolghasem
Supercritical carbon dioxide (SC-CO2)-based approaches have become more popular in recent years as alternative methods for creating micro- or nanosized medicines. Particularly, high drug solubility is required in those techniques using SC-CO2 as a solvent. During the most recent pandemic years, favipiravir and montelukast were two of the most often prescribed medications for the treatment of COVID-19. In this study, ethanol at 1 and 3 mol% was utilized as a cosolvent to increase the solubility of both medicines in SC-CO2 by a static approach using a range of temperatures (308 to 338 K) and pressure (12 to 30 MPa) values. The experimentally determined solubilities of favipiravir and montelukast in SC-CO2 + 3 mol% ethanol showed solubility values up to 33.3 and 24.5 times higher than that obtained for these drugs with only SC-CO2. The highest values were achieved in the pressure of 12 MPa and temperature of 338 K. Last but not least, six density-based semi-empirical models with various adjustable parameters were used to perform the modeling of the solubility of favipiravir and montelukast. © 2023 The Royal Society of Chemistry.
Correction to: Short-Term Meteorological and Environmental Signals Recorded in a Firn Core from a High-Accumulation Site on Plateau Laclavere, Antarctic Peninsula (Geosciences, (2021), 11, 10, (428), 10.3390/geosciences11100428)
(Multidisciplinary Digital Publishing Institute (MDPI), 2024) Hoffmann-Abdi, Kirstin; Fernandoy, Francisco; Meyer, Hanno; Freitag, Johannes; Opel, Thomas; McConnell, Joseph R.; Schneider, Christoph
The authors would like to make the following corrections to the published article [1]. In Section 1, fourth paragraph: In the sentence “Proxy Proxy data, such as glacio-chemical data from firn and ice cores, may partly compensate for the lack of direct observations.” the word “Proxy” should be deleted as it occurs twice. The sentence should have read: “Proxy data, such as glacio-chemical data from firn and ice cores, may partly compensate for the lack of direct observations.”. In Section 3.4, second paragraph: In the sentence “The slope of the δ18O–δD relationship (7.94) is close to that of the Global Meteoric Water Line (GMWL) [49] and is of the same order of magnitude as the slope of the site-specific LMWL (m = 7.76).” the “m =” should be deleted before “7.76” and “, 8” should be inserted after “GMWL”. The sentence should have read: “The slope of the δ18O–δD relationship (7.94) is close to that of the Global Meteoric Water Line (GMWL, 8) [49] and is of the same order of magnitude as the slope of the site-specific LMWL (7.76).”. In Section 4.5, first paragraph: In the sentence “Figure 8c,e visualise the anti-correlation between MLT and SIE in both the Bellingshausen-Amundsen Sea and the Weddell Sea (r > −0.6, p = 0; Table 5).” the “>” in the parenthesis should be replaced by “=”. The sentence should have read: “Figure 8c,e visualise the anti-correlation between MLT and SIE in both the Bellingshausen-Amundsen Sea and the Weddell Sea (r = −0.6, p = 0; Table 5).”. In the original publication, there was a mistake in Table 1 [1]. The order of the values in the column “Accumulation Rate (kg m−2 a−1)” was reversed for the years 2012 to 2015. The authors state that the scientific results for the accumulation rates in Table 1, which are presented and discussed in Sections 3.2 and 4.2 of the original publication, are not affected by this mistake, as all values were used correctly there. The corrected Table 1 is as follows: Annual accumulation rates calculated for the OH-12 drill site for the period 2012–2015. In the original publication, there was a mistake in Figure 6 [1]. The intercept in the equation for the δ18O−δD relationship of firn core OH-12 should be +6.01 and not −6.01. The corrected equation is δD = 7.94 × δ18O + 6.01. A correction was also made to the second paragraph in Section 3.4, where in the sentence “However, intercepts differ significantly (OH-12: −6.01; LMWL: −1.52; GMWL: +10), which is also reflected by the position of the OH-12 samples in the δ18O–δD plot (Figure 6a).” the intercept of the δ18O−δD relationship of firn core OH-12 should accordingly be +6.01 and not −6.01. In addition, in the same sentence the word “the” should be inserted before the word “intercepts”. The sentence should have read: ”However, the intercepts differ significantly (OH-12: +6.01; LMWL: −1.52; GMWL: +10), which is also reflected by the position of the OH-12 samples in the δ18O–δD plot (Figure 6a).”. The updated Figure 6 is as follows: (a) δ18O–δD relationship of all considered precipitation samples collected at Bernardo O’Higgins station (OH) between 2008 and 2017 (n = 294; coloured dots) compared to the δ18O–δD relationship of firn core OH-12 (n = 414; white dots). The Global Meteoric Water Line (GMWL) is indicated in blue. The Local Meteoric Water Line (LMWL) established for the study site by Fernandoy et al. [31,32] is shown as a dashed red line and the LMWL derived in this study as a solid red line. For each δ18O–δD relationship, the equation, the coefficient of determination (R2) and the p-value (p) are given. (b) Time series of δ18O, δD and d excess of OH-12 constructed based on the weighted age scale. High-resolution data are shown as light-coloured lines and monthly means as bold lines. The authors apologize for any inconvenience these mistakes may have caused the readers. The authors state that the scientific conclusions are unaffected. This correction was approved by the Academic Editor. The original publication has also been updated. © 2023 by the authors.
Voltage Regulation Enhancement of DC-MG Based on Power Accumulator Battery Test System: MPC-Controlled Virtual Inertia Approach
(Institute of Electrical and Electronics Engineers Inc., 2022-01-01) Long, Bo; Zeng, Wei; Rodriguez, Jose; Guerrero, Josep M.; Chong, Kil To
In a DC-microgrid (DC-MG) composed of a power accumulator battery test system (PABTS), owing to the low inertia of DC capacitance, the charging and discharging of a PABTS can easily cause DC-link voltage fluctuations, which may jeopardize the system stability. Hence, a virtual inertia control (VIC) strategy is proposed to suppress these fluctuations and enhance the stability of the DC-MG. The VIC method is realized in a bidirectional grid-connected converter (BGCC), which combines VIC and model predictive control (MPC). The proposed method can provide inertia support during the transient state and enhance the dynamic characteristics of the DC-link voltage. A prediction model is established that uses the variation range of the DC-link voltage as the constraint, and the output of VIC as well as voltage deviations as optimization objectives. The desired DC-link current increment is calculated using the prediction model to change the input DC current reference of the VIC. To validate the effectiveness of the proposed method, hardware-in-the-loop (HIL) experiments are performed, and the results indicate that MPC-VIC is superior to the existing VIC methods in terms of inertia support and the DC-link voltage variation suppression of PABTS DC-MGs. © 2010-2012 IEEE.
On stochastic aspects of impact modeling of the innovation incentive system and business internationalization: evidence from Portuguese SMEs
(Taylor and Francis Ltd., 2024) Grilo L.M.; Pereira E.J; Maidana J.P.; Stehlík M.
Multivariate normal distribution is base for many statistical techniques, including ordinary least square inference. Here we show that in order to make research on Internationalization of Companies, more flexible approach is needed, namely partial least squares (PLS). It is a nonparametric technique, used in Structural Equation Modeling (SEM), which makes no distributional assumptions and also may be applied with small sample sizes. In this study we discuss on regularity conditions for PLS from the perspective of semi-continuous covariance which fills the gap in the current studies. The stochastic aspects, especially those related to usage of PLS-SEM, can be well integrated to the topologically grounded regression, where jumps in the covariances can occur. The purpose of the research is to analyze and understand the impact of the Incentive System (IS) for Innovation, within the scope of the National Strategic Reference Framework (QREN) 2014-2020, on the Internationalization of Portuguese Small and Medium Enterprises (SMEs). We study stochastic aspects of theoretical model which aggregates the variables Product Innovation, Marketing Innovation, Organizational Innovation and Working Conditions as determinants of Internationalization of Companies. Data were collected based on a quantitative methodology, through a self-completion questionnaire using the Likert psychometric scale, which registered 120 participants. Organizational Innovation (exogenous latent construct) and Product Innovation have shown a statistically significant indirect effect on the Internationalization of Companies (endogenous latent construct) through Marketing Innovation. The latter has a direct effect on the Internationalization (target construct). However, Working Conditions has the greatest impact on Internationalization, meaning that measures such as increasing wages, decreasing the use of temporary work and precarious work conversion into labor effective relations have a very relevant direct effect on the Internationalization of Portuguese SMEs. © 2023 The Author(s). Published with license by Taylor & Francis Group, LLC.
School Greenness and Student-Level Academic Performance: Evidence From the Global South
(John Wiley and Sons Inc, 2023-08) Jimenez, Raquel B; Bozigar, Matthew; Janulewicz, Patricia; Lane, Kevin J.; Hutyra, Lucy R.; Fabian, M. Patricia
Greenspace in schools might enhance students' academic performance. However, the literature—dominated by ecological studies at the school level in countries from the Northern Hemisphere—presents mixed evidence of a beneficial association. We evaluated the association between school greenness and student-level academic performance in Santiago, Chile, a capital city of the Global South. This cross-sectional study included 281,695 fourth-grade students attending 1,498 public, charter, and private schools in Santiago city between 2014 and 2018. Student-level academic performance was assessed using standardized test scores and indicators of attainment of learning standards in mathematics and reading. School greenness was estimated using Normalized Difference Vegetation Index (NDVI). Linear and generalized linear mixed-effects models were fit to evaluate associations, adjusting for individual- and school-level sociodemographic factors. Analyses were stratified by school type. In fully adjusted models, a 0.1 increase in school greenness was associated with higher test scores in mathematics (36.9 points, 95% CI: 2.49; 4.88) and in reading (1.84 points, 95% CI: 0.73; 2.95); as well as with higher odds of attaining learning standards in mathematics (OR: 1.20, 95% CI: 1.12; 1.28) and reading (OR: 1.07, 95% CI: 1.02; 1.13). Stratified analysis showed differences by school type, with associations of greater magnitude and strength for students attending public schools. No significant associations were detected for students in private schools. Higher school greenness was associated with improved individual-level academic outcomes among elementary-aged students in a capital city in South America. Our results highlight the potential of greenness in the school environment to moderate educational and environmental inequalities in urban areas. © 2023 The Authors. GeoHealth published by Wiley Periodicals LLC on behalf of American Geophysical Union.
Distributed Predictive Secondary Control for Imbalance Sharing in AC Microgrids
(Institute of Electrical and Electronics Engineers Inc., 2022-01-01) Navas-Fonseca, Alex; Burgos-Mellado, Claudio; Gomez, Juan S.; Donoso, Felipe; Tarisciotti, Luca; Saez, Doris; Cardenas, Roberto; Sumner, Mark
This paper proposes a distributed predictive secondary control strategy to share imbalance in three-phase, three-wire isolated AC Microgrids. The control is based on a novel approach where the imbalance sharing among distributed generators is controlled through the control of single-phase reactive power. The main characteristic of the proposed methodology is the inclusion of an objective function and dynamic models as constraints in the formulation. The controller relies on local measurements and information from neighboring distributed generators, and it performs the desired control action based on a constrained cost function minimization. The proposed distributed model predictive control scheme has several advantages over solutions based on virtual impedance loops or based on the inclusion of extra power converters for managing single-phase reactive power among distributed generators. In fact, with the proposed technique the sharing of imbalance is performed directly in terms of single-phase reactive power and without the need for adding extra power converters into the microgrid. Contrary to almost all reported works in this area, the proposed approach enables the control of various microgrid parameters within predefined bands, providing a more flexible control system. Extensive simulation and Hardware in the Loop studies verify the performance of the proposed control scheme. Moreover, the controller's scalability and a comparison study, in terms of performance, with the virtual impedance approach were carried out. © 2010-2012 IEEE.

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