bluuebunny/crossref_metadata_2025 huggingface dataset:
Titanium Dioxide–Reduced Graphene Oxide Composites for Photocatalytic Degradation of Dyes in Water
Authors: Yu Lei , Xu Wenlong , Liu Huie , Bao Yan
Published: November 2022

Dye wastewater due to industrialization, urbanization and academic activities has become one of the most important environmental issues today. Photocatalytic degradation technology is considered as a promising technology for treating dye wastewater due to its advantages of environmental protection and low energy consumption. Herein, titanium dioxide–reduced graphene oxide composites (TiO2-RGO) were prepared by a one-step hydrothermal method to degrade different dyes (methyl orange, methylene blue and rhodamine B) in water. The structure and morphology of TiO2-RGO were characterized using various technical approaches. The degradation effect of TiO2-RGO on the dye was in accordance with a first-order kinetic reaction. The degradation rate of TiO2-6%RGO for methyl orange at 15 min was 1.67 times higher than that of TiO2, due to the strong electron transport ability and excellent adsorption properties of graphene. TiO2-6%RGO has better degradation performance for fluorescent dyes and anionic azo dyes. Notably, the degradation rate of methyl orange by TiO2-6%RGO photocatalysis for 90 min could reach 96.9%. Meanwhile, the TiO2-6%RGO showed excellent reusability, as the initial degradation rate of 93.2% was maintained after five degradation cycles of methyl orange solution. The present work provides a universal strategy for designing efficient photocatalytic materials.
Synthesis and Use of Silica Xerogels Doped with Iron as a Photocatalyst to Pharmaceuticals Degradation in Water
Authors: García-Reyes Cinthia Berenice , Salazar-Rábago Jacob J. , Polo Manuel Sánchez , Ramos Ventura Castillo
Published: November 2022

The main objective of this study was to assess the photoactive properties of iron-doped silica xerogels under solar radiation. For this purpose, silica xerogels (XGS) synthesized by the sol-gel method were doped with Fe (III) by two routes: impregnation and polymerization. XGS samples were texturally and chemically characterized by N2 adsorption, XRD, FTIR, Raman, SEM-EDX, DRS, and PL, evidencing the suitability of using XGS substrates to host iron clusters on their surface with total compatibility. Chlorphenamine (CPM), ciprofloxacin (CIP), and ranitidine (RNT) were used as model compounds. The degradation of the molecules was made under simulated solar radiation testing the synthesis pad, load, material size, and reuse. It was found that XGS doped with Fe by the impregnation route (XGS-Fe-Im) were able to completely degrade CPM and RNT in 30 min and 10 min, respectively, whilst for CIP it achieved the removal of 60% after 1 h of solar radiation exposure, outperforming parent materials and solar radiation by itself. The study of the degradation mechanism elucidated a major influence from the action of HO• radicals. The present investigation offers a potential route of application of XGS Fe-doped materials for the removal of emerging concern contaminants under near real-world conditions.
Chemerin-Induced Down-Regulation of Placenta-Derived Exosomal miR-140-3p and miR-574-3p Promotes Umbilical Vein Endothelial Cells Proliferation, Migration, and Tube Formation in Gestational Diabetes Mellitus
Authors: Zhang Lixia , Wu Qi , Zhu Shuqi , Tang Yibo , Chen Yanmin , Chen Danqing , Liang Zhaoxia
Published: November 2022

Gestational diabetes mellitus (GDM) leads to poor pregnancy outcomes and fetoplacental endothelial dysfunction; however, the underlying mechanisms remain unknown. This study aimed to investigate the effect of placenta-derived exosomal miRNAs on fetoplacental endothelial dysfunction in GDM, as well as to further explore the role of chemerin to this end. Placenta-derived exosomal miR-140-3p and miR-574-3p expression (next-generation sequencing, quantitative real-time PCR), its interactions with cell function (Cell Counting Kit-8, Transwell, tube formation assay), chemerin interactions (Western blotting), and placental inflammation (immunofluorescence staining, enzyme-linked immunosorbent assay) were investigated. Placenta-derived exosomal miR-140-3p and miR-574-3p were downregulated in GDM. Additionally, miR-140-3p and miR-574-3p inhibited the proliferation, migration, and tube formation ability of umbilical vein endothelial cells by targeting vascular endothelial growth factor. Interestingly, miR-140-3p and miR-574-3p expression levels were negatively correlated with chemerin, which induced placental inflammation through the recruitment of macrophage cells and release of IL-18 and IL-1β. These findings indicate that chemerin reduces placenta-derived exosomal miR-140-3p and miR-574-3p levels by inducing placental inflammation, thereby promoting the proliferation, migration, and tube formation of umbilical vein endothelial cells in GDM, providing a novel perspective on the underlying pathogenesis and therapeutic targets for GDM and its offspring complications.
Micro-Analytical Study of a Zeolites/Geo-Polymers/Quartz Composite, Dielectric Behaviour and Contribution to Brønsted Sites Affinity
Authors: Boughriet Abdel , Allahdin Oscar , Poumaye Nicole , Tricot Gregory , Revel Bertrand , Lesven Ludovic , Wartel Michel
Published: November 2022

The chemical and mineralogical surface properties of a brick-derived composite were examined by using an environmental scanning electron microscopy (ESEM) equipped with an energy dispersive X-ray spectrometer (EDS). Investigations revealed that the material could be assimilated to an adsorptive membrane having zeolites deposited onto quartz matrix. In our calculation, the membrane was considered as a diphase composite and its dielectric constant was evaluated from theoretical models developed in the literature. Electro-kinetic analysis showed that composite surfaces were hydroxylated with the formation of hydroxyl groups which behaved amphoterically. A theory-based approach was used for calculating thermodynamic constants relative to surface-protonation equilibriums. In the H-form of the composite, the occurrence of bridging Si–(OH)–Al sites were evidenced by mathematical calculations utilizing equations in direct relation to mineralogical, crystallographic and dielectric surface characteristics. 1H MAS NMR spectroscopy confirmed the existence of bridging Brønsted acid sites at acidified composite surfaces interacting with ammonium (as probe ions). Owing to advancements in brick-based composites research, this should lead more to the development of “ceramic” adsorptive membranes with natural clay materials.
Understanding the Knowledge, Attitudes, and Practices of Healthcare Professionals toward Climate Change and Health in Minnesota
Authors: Kircher Madison , Doheny Brenna , Raab Kristin , Onello Emily , Gingerich Stephanie , Potter Teddie
Published: November 2022

Climate change is an urgent public health issue that is impacting health locally and across the world. Healthcare professionals are on the front lines for public health, caring for people affected by climate change; yet few studies have assessed their knowledge and experiences of local climate change effects. The purpose of this study was to improve our understanding of the health impacts of climate change in Minnesota from the perspective of healthcare professionals. An electronic survey was administered by the Minnesota Department of Health (MDH) to a convenience sample of Board-certified nurses and physicians in Minnesota. Seventy-five percent of respondents agreed that climate change is happening, and 60% agreed that it is currently impacting the health of their patients. However, only 21% felt well prepared to discuss climate change, and only 4% discussed climate change with all or most of their patients. Similarly, results from open-ended questions highlighted the importance of climate change and acknowledged the challenges of discussing this topic. While most respondents recognized the health impacts of climate change, they also reported feeling uncomfortable discussing climate change with patients. Thus, there is an opportunity to develop targeted resources to support healthcare professionals in addressing climate change.
An Automated, Self-Powered, and Integrated Analytical Platform for On-Line and In Situ Air Quality Monitoring
Authors: da Silva Sousa Danielle , Leal Vanderli Garcia , dos Reis Gustavo Trindade , da Silva Sidnei Gonçalves , Cardoso Arnaldo Alves , da Silveira Petruci João Flávio
Published: November 2022

Air quality monitoring networks are challenging to implement due to the bulkiness and high prices of the standard instruments and the low accuracy of most of the described low-cost approaches. This paper presents a low-cost, automated, self-powered analytical platform to determine the hourly levels of O3 and NO2 in urban atmospheres. Atmospheric air was sampled at a constant airflow of 100 mL min−1 directly into vials containing 800 µL of indigotris sulfonate and the Griess–Saltzman reagent solutions for ozone and nitrogen dioxide, respectively. The analysis holder, containing a light-emitting diode and a digital light sensor, enabled the acquisition of the analytical signal on-site and immediately after the sampling time. The data were transmitted to a laptop via Bluetooth, rendering remote hourly monitoring. The platform was automated using two Arduino Uno boards and fed with a portable battery recharged with a solar panel. The method provided a limit of detection of 5 and 1 ppbv for O3 and NO2, respectively, which is below the maximum limit established by worldwide regulatory agencies. The platform was employed to determine the levels of both pollutants in the atmosphere of two Brazilian cities, in which one of them was equipped with an official air quality monitoring station. Comparing the results of both techniques revealed suitable accuracy for the proposed analytical platform. Information technology (IT) allied to reliable chemical methods demonstrated high potential to create air quality monitoring networks providing valuable information on pollutants’ emissions and ensuring safety to the population.
Social, Educational and Medical Aspects after Cataract Surgery of Bilaterally Blind Children in Kinshasa—Perception of Parents and Children
Authors: Frech Stefanie , Hopkins Adrian , Moanda Astrid , Kilangalanga Janvier , Guthoff Rudolf F.
Published: November 2022

The study investigated the influence of bilateral cataract surgery on the social and educational development of previously bilaterally blind children in Sub-Saharan Africa (SSA), where the prevalence of blindness due to cataract is higher than in high-income countries. The views of both, parents and children, were evaluated with structured interviews based on a newly developed questionnaire related to surgery, follow-up, and family life after surgery. The mean age of the children at interview was 14.4 ± 8.1 years, with 27 females and 26 males. Satisfaction with the outcome of the surgery was reported by 91% of parents. Parents would recommend surgery, because of the children being happy and able to act more independently, with personal, educational and familial factors essentially contributing to the reported satisfaction. The results also showed that 85.0% of children did not wear eyeglasses. Reasons given were mainly cost-related, but also included limited communication between families and health institutions. Providing and maintaining a high-quality and accessible pediatric cataract surgery and healthcare service for follow-up is a major requisite to reduce childhood blindness in SSA. Our study proved the necessity and effectiveness of a community-based rehabilitation program that cares about each individual child, whatever his or her social background.
Thermochemical Conversion of Sugarcane Bagasse: A Comprehensive Analysis of Ignition and Burnout Temperatures
Authors: Morais Leandro C. de , Maia Amanda A. , Resende Pedro R. , Rosa André H. , Nunes Leonel J. R.
Published: November 2022

The Brazilian sugarcane industry generates a significant amount of waste each year, which should be properly analyzed and studied to allow an adequate recovery and application supported by the best understanding of its properties. The present work reports the ignition and burnout temperatures of sugarcane bagasse (SCB) obtained after performing a thermal analysis using four different heating rates. The intersection method (IM) and deviation method (DM) were employed to approach the ignition and burnout temperatures of the sugarcane bagasse. The ignition temperatures of the SCB measured from IM are between 250 and 263 °C, and their burnout temperatures are between 357 and 377 °C. The ignition temperature was in the range of 205 °C to 236 °C for the DM. IM is recommended for determining the ignition and burnout temperatures. In TGA, the heating rates in the range of 10 °C·min−1 and 15 °C·min−1 are suggested due to their accuracy and the contribution to timesaving in the analysis.
Extraction of Polyphenolic and Volatile Compounds from Cistus creticus Using Deep Eutectic Solvents and Pulsed Electric Fields
Authors: Palaiogiannis Dimitrios , Athanasiadis Vassilis , Bozinou Eleni , Chatzimitakos Theodoros , Makris Dimitris P. , Lalas Stavros I.
Published: November 2022

To date, many studies have been published, aiming to extract bioactive compounds from plants. Lately, research focuses on maximizing the extraction yield, using environmentally friendly techniques and solvents. In this study, the extraction of polyphenolic compounds from Cistus creticus is discussed. Extraction of the compounds has been carried out with water and ethanol, employing the most common approach. To further enhance the extraction yield, the usage of four deep eutectic solvents (DESs) has also been examined. In an effort to further enhance the extraction yield, pulsed electric fields have also been employed. According to the results, it was evident that the use of DESs made of glycerol: choline chloride (2:1) increased the extraction yield by 75%, compared to extraction with water. Moreover, the use of pulsed electric fields enhanced the extraction yield of the common approach, by up to 70%. When pulsed electric fields and DESs were combined, the extraction yield increased by 14%, compared to the use of DESs only. Finally, the extract was analyzed for its content in volatile compounds, and it was found that new compounds could be extracted with the use of DESs.
Harmony in Conservation
Authors: Washington Haydn , Gomez-Baggethun Erik , Piccolo John J. , Kopnina Helen , Alberro Heather
Published: November 2022

Many authors have noted the role that anthropocentrism has played in creating humanity’s dysfunctional relationship with the natural world. As human hubris (excessive pride or self-confidence) is an ailment that contributes to the anthropogenic sixth mass extinction of Earth’s biodiversity, we argue instead for ‘harmony with nature’. In recent decades, even the conservation discourse has become increasingly anthropocentric. Indeed, justification for nature conservation has in part shifted from nature’s intrinsic value to ‘ecosystem services’ for the benefit of people. Here we call for a transformation to a more harmonious human-nature relationship that is grounded in mutual respect and principled responsibility, instead of utilitarianism and enlightened self-interest. Far from what Tennyson called ‘red in tooth and claw’, we argue nature is a mixture of cooperation as well as competition. We argue that the UN’s ‘Harmony with Nature’ program is an innovative and refreshing path for change. If we are to achieve harmony with nature, modern industrial society will need to abandon its anthropocentric ‘human supremacy’ mindset and adopt an ecocentric worldview and ecological ethics. We conclude it is thus both appropriate (and essential) for conservationists to champion harmony with nature.
Health Benefits and Safety of Red Pigmented Rice (Oryza sativa L.): In Vitro, Cellular, and In Vivo Activities for Hair Growth Promoting Treatment
Authors: Thitipramote Natthawut , Imsonpang Supapong , Sukphopetch Passanesh , Pradmeeteekul Prinyaporn , Nimkamnerd Junniphaphorn , Nantitanon Witayapan , Chaiyana Wantida
Published: November 2022

The hair growth-promoting activities of Thai native red (Sang-Yod-SY and Mun-Poo-MP) and black (Black glutinous-BG and Hom-Nil-HN) pigmented rice (Oryza sativa L.) extracts, including in vitro 5α-reductase inhibition, hair growth-promoting activity on human hair germinal matrix cells, and in vivo hair-cycle-converting activity in C3H/HeMlac mice, were investigated. Moreover, these extracts were determined to be safe via cytotoxicity (HaCaT cell) and in vivo irritation tests. The results showed that SY red rice extract with high contents of proanthocyanidin (1.50 ± 0.16 mgECE/g extract) exhibited significantly higher 5α-reductase inhibitory activity (18.5 ± 9.0 mgFEA/g extract) (p < 0.05). The maximum growth-promoting activity for human matrix cells treated with SY extract reached about 216.2 ± 0.7% (1 mg/mL) relative to control (100%) after 3 days culture (p < 0.05). Moreover, topical application of 1 mg/mL SY red pericarp rice extracts on shaven C3H skin in telogen phase led to significant hair regeneration (97.2 ±1.3%) based on the shaven area, while vehicle application only tended to yield a regeneration of 50.9 ± 11.7%. Red rice extracts were found to be safe, without signs of cytotoxicity and irritation. This research demonstrates the health benefits and safety of SY red pericarp extract when used for hair growing activity and its potential for use as a natural hair growth promoter and 5α-reductase inhibitor.
The Effect of Aluminum Particle Size on the Formation of Reactive Jet
Authors: Guo Mengmeng , Wang Yanxin , Chen Yongkang , Xiao Jianguang , Wang Haifu
Published: November 2022

In order to study the morphology characteristics of the PTFE/Al reactive shaped charge jet and the chemical reaction during the jet formation, PTFE/Al reactive liners with aluminum particle sizes of 5 μm and 100 μm were prepared. The parameters of the Johnson–Cook constitutive model of PTFE/Al reactive materials (RMs) were obtained through quasi-static compression experiments and SHPB (Split Hopkinson Pressure Bar) experiments. X-ray imaging technology was used to photograph the shape of reactive shaped charges jet at two different time points. The AUTODYN secondary development technology was used to simulate the jet formation, and the simulation results are compared with the experimental results. The results show that the simulation results are close to the experimental results, and the error is in the range of 4–8%. Through analysis, it is observed that the RMs reacted during the PTFE/Al reactive shaped charge jet formation, and due to the convergence of the inner layer of the liner during the jet formation, the chemical reaction of the jet is from inside to outside. Secondly, the particle size of aluminum powder has an influence on the chemical reaction and morphology of the jet. During the jet formation, there were fewer RMs reacted when the PTFE/Al reactive liners were prepared with 100 μm aluminum powder. Compared with 5 μm aluminum powder, when the aluminum powder is 100 μm, the morphology of the jet is more condensed, which is conducive to generating greater penetration depth.
Fractional Flow Reserve-Guided Coronary Revascularization: Evidence from Randomized and Non-Randomized Studies
Authors: Paolucci Luca , Mangiacapra Fabio , Viscusi Michele Mattia , Nusca Annunziata , Zimbardo Giuseppe , Cialdella Pio , Donahue Michael Edward , Calò Leonardo , Ussia Gian Paolo , Grigioni Francesco
Published: November 2022

Simple visual estimation of coronary angiography is limited by several factors that can hinder the proper classification of coronary lesions. Fractional flow reserve (FFR) is the most widely used tool to perform a physiological evaluation of coronary stenoses. Compared to isolated angiography, FFR has been demonstrated to be more effective in selecting those lesions associated with myocardial ischemia and, accordingly, impaired outcomes. At the same time, deferring coronary intervention in those lesions that do not show ischemic FFR values has proven safe and not associated with adverse events. Despite a major randomized clinical trial (RCT) and several non-randomized studies showing that FFR-guided revascularization could be superior to isolated angiography in improving clinical outcomes, subsequent RCTs have reported conflicting results. In this review, we summarize the principles behind FFR and the data currently available in the literature, highlighting the main differences between randomized and non-randomized studies that investigated this topic.
A Lower False Positive Pulmonary Nodule Detection Approach for Early Lung Cancer Screening
Authors: Zheng Shaohua , Kong Shaohua , Huang Zihan , Pan Lin , Zeng Taidui , Zheng Bin , Yang Mingjing , Liu Zheng
Published: November 2022

Pulmonary nodule detection with low-dose computed tomography (LDCT) is indispensable in early lung cancer screening. Although existing methods have achieved excellent detection sensitivity, nodule detection still faces challenges such as nodule size variation and uneven distribution, as well as excessive nodule-like false positive candidates in the detection results. We propose a novel two-stage nodule detection (TSND) method. In the first stage, a multi-scale feature detection network (MSFD-Net) is designed to generate nodule candidates. This includes a proposed feature extraction network to learn the multi-scale feature representation of candidates. In the second stage, a candidate scoring network (CS-Net) is built to estimate the score of candidate patches to realize false positive reduction (FPR). Finally, we develop an end-to-end nodule computer-aided detection (CAD) system based on the proposed TSND for LDCT scans. Experimental results on the LUNA16 dataset show that our proposed TSND obtained an excellent average sensitivity of 90.59% at seven predefined false positives (FPs) points: 0.125, 0.25, 0.5, 1, 2, 4, and 8 FPs per scan on the FROC curve introduced in LUNA16. Moreover, comparative experiments indicate that our CS-Net can effectively suppress false positives and improve the detection performance of TSND.
Shannon Entropy: An Econophysical Approach to Cryptocurrency Portfolios
Authors: Rodriguez-Rodriguez Noé , Miramontes Octavio
Published: November 2022

Cryptocurrency markets have attracted many interest for global investors because of their novelty, wide on-line availability, increasing capitalization, and potential profits. In the econophysics tradition, we show that many of the most available cryptocurrencies have return statistics that do not follow Gaussian distributions, instead following heavy-tailed distributions. Entropy measures are applied, showing that portfolio diversification is a reasonable practice for decreasing return uncertainty.
Equilibrium and Non-Equilibrium Lattice Dynamics of Anharmonic Systems
Authors: Esfarjani Keivan , Liang Yuan
Published: November 2022

In this review, motivated by the recent interest in high-temperature materials, we review our recent progress in theories of lattice dynamics in and out of equilibrium. To investigate thermodynamic properties of anharmonic crystals, the self-consistent phonon theory was developed, mainly in the 1960s, for rare gas atoms and quantum crystals. We have extended this theory to investigate the properties of the equilibrium state of a crystal, including its unit cell shape and size, atomic positions and lattice dynamical properties. Using the equation-of-motion method combined with the fluctuation–dissipation theorem and the Donsker–Furutsu–Novikov (DFN) theorem, this approach was also extended to investigate the non-equilibrium case where there is heat flow across a junction or an interface. The formalism is a classical one and therefore valid at high temperatures.
Structure and Dynamics of dsDNA in Cell-like Environments
Authors: Singh Amar , Maity Arghya , Singh Navin
Published: November 2022

Deoxyribonucleic acid (DNA) is a fundamental biomolecule for correct cellular functioning and regulation of biological processes. DNA’s structure is dynamic and has the ability to adopt a variety of structural conformations in addition to its most widely known double-stranded DNA (dsDNA) helix structure. Stability and structural dynamics of dsDNA play an important role in molecular biology. In vivo, DNA molecules are folded in a tightly confined space, such as a cell chamber or a channel, and are highly dense in solution; their conformational properties are restricted, which affects their thermodynamics and mechanical properties. There are also many technical medical purposes for which DNA is placed in a confined space, such as gene therapy, DNA encapsulation, DNA mapping, etc. Physiological conditions and the nature of confined spaces have a significant influence on the opening or denaturation of DNA base pairs. In this review, we summarize the progress of research on the stability and dynamics of dsDNA in cell-like environments and discuss current challenges and future directions. We include studies on various thermal and mechanical properties of dsDNA in ionic solutions, molecular crowded environments, and confined spaces. By providing a better understanding of melting and unzipping of dsDNA in different environments, this review provides valuable guidelines for predicting DNA thermodynamic quantities and for designing DNA/RNA nanostructures.
High School Students’ Performances in Transitions between Different Representations of Linear Relationships in Mathematics and Physics
Authors: Testa Italo , Catena Danilo
Published: November 2022

This study involved 643 high school students to assess their performance in using different representations of linear functions—graphs, tables, and algebraic relationships—in mathematics and kinematics. The results show that students encounter greater difficulties when they have to interpret representations involving algebraic relations in mathematics. Furthermore, it is shown how the ability to switch from one type of representation to another is influenced by spatial reasoning skills, orientation toward physics, and self-confidence in the field of mathematics and physics. Implications for teaching kinematics and linear functions are briefly discussed.
Indirect Evaluation of the Electrocaloric Effect in PbZrTiO3 (20/80)-Based Epitaxial Thin Film Structures
Authors: Boni Georgia A. , Filip Lucian D. , Radu Cristian , Chirila Cristina , Pasuk Iuliana , Botea Mihaela , Pintilie Ioana , Pintilie Lucian
Published: November 2022

Electrocaloric effect is the adiabatic temperature change in a dielectric material when an electric field is applied or removed, and it can be considered as an alternative refrigeration method. Materials with ferroelectric order exhibit large temperature variations in the vicinity of a phase transition, while antiferroelectrics and relaxors may exhibit a negative electrocaloric effect. In this study, the temperature variation in polarization was investigated for epitaxial ferroelectric thin film structures based on PbZrTiO3 materials in simple or complex multilayered structures. We propose the intriguing possibility of a giant negative electrocaloric effect (ΔT = −3.7 K at room temperature and ΔT = −5.5 K at 370 K) in a simple epitaxial Pb(ZrTi)O3 capacitor. Furthermore, it was shown that abnormal temperature variation in polarization is dependent on the non-FE component introduced in a multilayered structure. No significant variation in polarization with temperature was obtained for PZT/STON multilayered structures around room temperature. However, for PZT/BST or PZT/Nb2O5 multilayers, an abnormal temperature variation in polarization was revealed, which was similar to a simple PZT layer. The giant and negative ∆T values were attributed to internal fields and defects formed due to the large depolarization fields when the high polarization of the FE component was not fully compensated either by the electrodes or by the interface with an insulator layer. The presented results make Pb(ZrTi)O3-based structures promising for cooling applications operating near room temperature.
Correction: He et al. A 3.95 ppm/°C 7.5 μW Second-Order Curvature Compensated Bandgap Reference in 0.11 μm CMOS. Electronics 2022, 11, 2869
Authors: He Yuefeng , Yuan Guoshun , Lei Lei , Yu Hongjiang , Kong Dewei
Published: November 2022

In the published publication [...]
A Mathematical Modeling Approach for Power Flow and State Estimation Analysis in Electric Power Systems through AMPL
Authors: Ruiz Florez Hugo A. , López Gloria P. , Jaramillo-Duque Álvaro , López-Lezama Jesús M. , Muñoz-Galeano Nicolás
Published: November 2022

This paper presents a mathematical modeling approach by which to solve the power flow and state estimation problems in electric power systems through a mathematical programming language (AMPL). The main purpose of this work is to show the advantages of representing these problems through mathematical optimization models in AMPL, which is a modeling language extensively used in a wide range of research applications. The proposed mathematical optimization models allow for dealing with particular issues in that they are not usually considered in the classical approach for power flow and state estimation, such as solving the power flow problem considering reactive power limits in generation buses, as well as the treatment of errors in state estimation analysis. Furthermore, the linearized mathematical optimization models for both problems at hand are also presented and discussed. Several tests were carried out to validate the proposed optimization models, evidencing the applicability of the proposed approach.
Improving Path Accuracy of Mobile Robots in Uncertain Environments by Adapted Bézier Curves
Authors: Șomîtcă Ioana-Alexandra , Brad Stelian , Florian Vlad , Deaconu Ștefan-Eduard
Published: November 2022

An algorithm that presents the best possible approximation for the theoretical Bézier curve and the real path on which a mobile robot moves in a dynamic environment with mobile obstacles and boundaries is introduced in this paper. The algorithm is tested on a set of scenarios that comprehensively cover critical situations of obstacle avoidance. The selection of scenarios is made by deploying robot navigation performances into constraints and further into descriptive characteristics of the scenarios. Computer-simulated environments are created with dedicated tools (i.e., Gazebo) and modeling and programming technologies (i.e., Robot Operating System (ROS) and Python). It is shown that the proposed algorithm improves the performance of the path for robot navigation in a highly dynamic environment, with dense mobile obstacles.
MTDOT: A Multilingual Translation-Based Data Augmentation Technique for Offensive Content Identification in Tamil Text Data
Authors: Ganganwar Vaishali , Rajalakshmi Ratnavel
Published: November 2022

The posting of offensive content in regional languages has increased as a result of the accessibility of low-cost internet and the widespread use of online social media. Despite the large number of comments available online, only a small percentage of them are offensive, resulting in an unequal distribution of offensive and non-offensive comments. Due to this class imbalance, classifiers may be biased toward the class with the most samples, i.e., the non-offensive class. To address class imbalance, a Multilingual Translation-based Data augmentation technique for Offensive content identification in Tamil text data (MTDOT) is proposed in this work. The proposed MTDOT method is applied to HASOC’21, which is the Tamil offensive content dataset. To obtain a balanced dataset, each offensive comment is augmented using multi-level back translation with English and Malayalam as intermediate languages. Another balanced dataset is generated by employing single-level back translation with Malayalam, Kannada, and Telugu as intermediate languages. While both approaches are equally effective, the proposed multi-level back-translation data augmentation approach produces more diverse data, which is evident from the BLEU score. The MTDOT technique proposed in this work achieved a promising improvement in F1-score over the widely used SMOTE class balancing method by 65%.
Analysis of Short-Circuit and Dielectric Recovery Characteristics of Molded Case Circuit Breaker according to External Environment
Authors: Cho Young-Maan , Park Hyun-Jong , Lee Ho-Joon , Lee Kun-A
Published: November 2022

A molded case circuit breaker (MCCB) is one of the most important factors for safety to protect a load from overcurrent in a power distribution system. MCCB, which is mainly installed in switchboards and distribution boxes, may be affected by external temperatures and magnetic fields, but the above factors are still excluded from product standards and performance evaluation. This paper is the result of experimenting and studying the negative effects of these external temperatures and external magnetic fields on MCCB with short-circuit characteristic and dielectric recovery strength. As a result of temperature, it can be found that both short-circuit characteristic and dielectric recovery strength change linearly in accordance with the external temperature. The ratio of the values of 35 °C to 25 °C and 45 °C to 25 °C show the following results. t10, t21, and t32 are 1.58, 1.53, and 1.79, respectively, in short-circuit characteristics and ti, tm, and tl are 1.59, 1.69, and 1.53, respectively, in dielectric recovery strength. Depending on the external magnetic field, the short-circuit characteristics decreased by 8.56% only in the t21 period. The dielectric recovery strength decreases by 4.92% in the initial section (ti) and 14.45% in the later section (tl), respectively. It has been confirmed that the external magnetic field interferes with the emission of hot gas.
A Video-Based Real-Time Tracking Method for Multiple UAVs in Foggy Weather
Authors: Dai Jiashuai , Wu Ling , Wang Pikun
Published: November 2022

Aiming at the real-time tracking problem of multiple unmanned aerial vehicles (UAVs) based on video under fog conditions, we propose a multitarget real-time tracking method that combines the Deepsort algorithm with detection based on improved dark channel defogging and improved You Only Look Once version 5 (YOLOv5) algorithm. The contributions of this paper are as follows: 1. For the multitarget tracking problem under fog interference, a multialgorithm combination method is proposed. 2. By optimizing dark channel defogging, the complexity of the original algorithm is reduced from On2 to On, which simplifies the processing time of the defogging algorithm. 3. The YOLOv5 network structure is optimized so that the network can synchronously reduce the detection time while maintaining high-precision detection. 4. The amount of algorithm processing through image size compression is reduced, and the real-time performance under high-precision tracking is improved. In the experiments conducted, the proposed method improved tracking precision by 36.1% and tracking speed by 39%. The average time of tracking per image frame was 0.036s, satisfying the real-time tracking of multiple UAVs in foggy weather.
Identifying the Acoustic Source via MFF-ResNet with Low Sample Complexity
Authors: Cui Min , Liu Yang , Wang Yanbo , Wang Pan
Published: November 2022

Acoustic signal classification plays a central role in acoustic source identification. In practical applications, however, varieties of training data are typically inadequate, which leads to a low sample complexity. Applying classical deep learning methods to identify acoustic signals involves a large number of parameters in the classification model, which calls for great sample complexity. Therefore, low sample complexity modeling is one of the most important issues related to the performance of the acoustic signal classification. In this study, the authors propose a novel data fusion model named MFF-ResNet, in which manual design features and deep representation of log-Mel spectrogram features are fused with bi-level attention. The proposed approach involves an amount of prior human knowledge as implicit regularization, thus leading to an interpretable and low sample complexity model of the acoustic signal classification. The experimental results suggested that MFF-ResNet is capable of accurate acoustic signal classification with fewer training samples.
Exergy, Economic and Environmental Analysis of a Direct Absorption Parabolic Trough Collector Filled with Porous Metal Foam
Authors: Khattar Murtadha , Heyhat Mohammad
Published: November 2022

A direct absorption parabolic trough solar collector (DAPTC) integrated with porous foam as a volumetric absorber has the potential to be applied as an energy conversion integrant of future renewable energy systems. The present study comprehensively analyzes a DAPTC in terms of exergy, economic, and environmental analysis for different porous configuration inserts in the absorber tube. Ten different arrangements of porous foam are examined at several HTF flow rates (40–120 L/h) and inlet temperatures (20–40 °C). The exergy efficiency, entropy generation, Bejan number, and pumping power are investigated for all cases. Obtained results indicate that fully filling the absorber tube with porous foam leads to a maximum exergy efficiency of 20.4% at the lowest inlet temperature (20 °C) and highest flow rate (120 L/h). However, the Bejan number reaches its minimum value due to the highest pumping power in this case. Consequently, all mentioned performance parameters should be considered simultaneously. Finally, the environmental and economic analyses are conducted. The results show that fully filling the absorber tube with porous foam reflects the best heat production cost, which can reduced the embodied energy, embodied water, and CO2 emission by 559.5 MJ, 1520.8 kL, and 339.62 kg, respectively, compared to the base case at the flow rate of 120 L/h.
Optimal Control of a PHEV Based on Backward-Looking Model Extended with Powertrain Transient Effects
Authors: Soldo Jure , Cvok Ivan , Deur Joško
Published: November 2022

The paper proposes a power flow control strategy for a P2 parallel plug-in hybrid electric vehicle (PHEV) which takes into account torque and power losses related to engine-on and gear shift transients. An extended backward-looking (EXT-BWD) model is proposed to account for the transient losses, while the control strategy combines a rule-based controller with an equivalent consumption minimization strategy. To describe the transient losses, the EXT-BWD model includes additional state variables related to engine on/off flag and gear ratio in the previous time step. To establish a performance benchmark for control strategy verification, a dynamic programming-based control variable optimization framework is established based on the EXT-BWD model. The proposed control strategy is demonstrated to improve the fuel efficiency and drivability compared to the original control strategy while retaining comparable computational efficiency.
Analysis of Characteristics of Low Voltage Circuit Breaker by External Magnetic Field
Authors: Cho Young-Maan , Park Hyun-Jong , Lee Jae-Jun , Lee Kun-A
Published: November 2022

Recently, as interest in eco-friendly distributed power has increased, studies on the improvement of the performance of breakers such as DC breakers and on the reliability of existing AC breakers have been actively conducted. To improve the performance and reliability of these breakers, this paper conducted the analysis of characteristics of a low voltage circuit breaker using an external magnetic field. In this experiment, before the current-zero point, the cut-off time to improve the breaker performance is shortened and after the current-zero point, re-ignition, which is associated with reliability, is suppressed. According to the experimental results, the short-circuit characteristics before current-zero show a significant difference of 0.13 ms in the t21 section, and the dielectric recovery strength after current-zero shows a 13.3% performance improvement in the latter half of the DRV (dielectric recovery voltage) V-t curve. This result has significant meaning because it can be easily improved under the control of the external magnetic field. Hence, it can be applied to the interruption performance improvement of breakers through detailed research in the future.
Cleaning of Photovoltaic Panels Utilizing the Downward Thrust of a Drone
Authors: Rehman S. , Mohandes M. A. , Hussein A. E. , Alhems L. M. , Al-Shaikhi A.
Published: November 2022

This study demonstrates that a drone flying above photovoltaic (PV) panels can clean the dust and enhance the panels’ efficiency. If operated regularly, the drone’s downward thrust generated during its cruise at a certain height above the panels can remove most of the accumulated dust. Sandstorms are frequent in Saudi Arabia, creating dust deposition on PV panels, which acts as a shield against solar radiation. As a result, the energy absorption from solar radiation is reduced and subsequently, the panels’ energy output is reduced. This experimental investigation was conducted at KFUPM University’s beach, Dhahran, Saudi Arabia, to prove the effectiveness of drone-based cleaning of PV panels. Volumes of 20, 50, and 100 CC of dust were spread on the panel during different experiments. These experimental results showed that the back thrust of the drone could remove most of the dust and improve the solar panels’ energy output performance. For example, for 50 CC dust spread on the panel, the current increased from 1.34 A to 2.16 A (61.2% increase), relative to the pre- and post-drone flight for horizontal movement of the drone. Similarly, for vertical and diagonal movements, the current increased by 69.83% and 68.03%, respectively, for a dust spread of 20 CC. Furthermore, dust reductions of 74.64%, 57.0%, and 78.4% were realized during the horizontal, vertical, and diagonal paths, respectively, of the drone flight for 50 CC dust spread.
Performance Prediction and Working Fluid Active Design of Organic Rankine Cycle Based on Molecular Structure
Authors: Pan Yachao , Yang Fubin , Zhang Hongguang , Yan Yinlian , Yang Anren , Liang Jia , Yu Mingzhe
Published: November 2022

Working fluid selection is crucial for organic Rankine cycles (ORC). In this study, the relationship between molecular structure and ORC performance was established based on the quantitative structure–property relationship (QSPR) and working fluid parameterized model (WFPM), from which an ORC working fluid was actively designed. First, the QSPR model with four properties, namely, critical temperature (Tc), boiling point (Tb), critical pressure (pc), and isobaric heat capacity (cp0), was built. Second, the evaporation enthalpy (hvap), evaporation entropy (svap), and thermal efficiency (η) were estimated by WFPM, and the results were compared with those using REFPROP to verify the calculation accuracy of the “QSPR+WFPM” coupling model. The average absolute relative deviations of evaporation enthalpy and entropy are below 8.44%. The maximum relative error of thermal efficiency is 6%. Then, the thermodynamic performance limit of ORC and corresponding thermophysical properties of the ideal working fluid were calculated at typical geothermal source conditions. Finally, the active design of the working fluid was conducted with the ideal working fluid Tc and pc as the target. The research shows that C3H4F2 and C4H3F5 are optimal working fluids at 473.15 and 523.15 K heat sources, respectively.
Measurement-Based Nonlinear SPICE-Compatible Photovoltaic Models for Simulating the Effects of Surges and Electromagnetic Interference within Installations
Authors: Coetzer Kurt Michael , Rix Arnold Johan , Wiid Pieter Gideon
Published: November 2022

An emerging area of interest within photovoltaic (PV) centred research is the simulation of the propagation of electromagnetic interference (EMI) and surges within PV installations. An overarching constraint in all simulation-based research is the accuracy of the models employed. In general, for PV-focussed simulations, nonlinear models are utilised for direct current (DC) analyses, whilst linearised models are employed for analyses involving surges or conducted electromagnetic interference. For large-signal electromagnetic interference and surges, the following two problems arise: (1) the aforementioned linearisation is only valid for the small-signal case, and (2) as they are constructed using only DC measurements, traditional large-signal PV models are generally only valid for DC conditions. Therefore, neither of these approaches can properly represent real-world PV behaviour under dynamic conditions. To overcome this limitation, this article proposes a more suitable model, compatible with Simulation Program with Integrated Circuit Emphasis (SPICE), and which results from the combination of two sub-models: one for large-signal DC cases, and one for small-signal alternating current (AC) cases. Consequently, the combined model enables improved modelling of the effects of large-signal transient perturbations to be performed, as well as cases involving small-signal AC and large-signal DC perturbations. The model parameters are extracted using data from two different classes of measurement setups: the first utilised a vector network analyser (VNA) to produce small-signal AC impedance results (covering a frequency range between 1 Hz and 50 MHz), and the second produces DC current-voltage curves. Both classes of measurement setup consider the device under test at multiple operating points. Key results include: (1) an improved SPICE-compatible PV model which caters for large-signal transient simulations, as well as for small-signal AC and large-signal DC cases, (2) improvements in the modelling of reverse bias behaviour when compared to the standard SPICE diode implementation, (3) the correct implementation of a voltage-dependent total capacitance (suitable for large-signal simulations), (4) modelling parameters for both a small (10 W) and a large (310 W) PV module, (5) measurement results which de-embedded the parasitic effects of the test setups employed, and (6) above 1 MHz, the physical layouts of the cells within the PV modules begin to influence the observed impedances.
Environmental Impact Comparison of Geothermal Alternatives for Conventional Boiler Replacement
Authors: Lorente Rubio Carlos , García-Alcaraz Jorge Luis , Sáenz-Diez Muro Juan Carlos , Martínez-Cámara Eduardo , Bruzzone Agostino , Blanco-Fernández Julio
Published: November 2022

In the transition towards a sustainable world with a “green horizon” (something that is also of great importance to the policy of energy self-sufficiency in housing and self-consumption), geothermal energy is seen as quite a feasible alternative for single-family homes. This article focuses on a comparison between the environmental impact and life cycle analysis of three alternatives and provides a base case for the replacement of a conventional type of boiler with a geothermal one for a typical house located in a Mediterranean climate. The first alternative (A) consists of a horizontal catchment system through a field of geothermal probes. The second alternative (B) is a shallow water catchment system, open type, with the return of water to a nearby river. The third option studied (C) is also a shallow water catchment system but with the water, return injected into a well downstream to the underground water flow. The study shows that alternatives A and B have the least environmental impact in most of the categories studied. The total amortization periods for the three alternatives and the base case differ by almost two years, with alternative A taking 6.99 years and alternative C costing 8.82 years.