bluuebunny/crossref_metadata_2025 huggingface dataset:
An International Collaborative Initiative to Establish a Quality-of-Life Questionnaire for Children and Adolescents with Repair of Esophageal Atresia in 14 Countries
Authors:   The International EA-QOL Group
Published: February 2024

The EA-QOL questionnaire measures quality-of-life specifically for children born with esophageal atresia (EA) aged 8–18 and was completed in Sweden and Germany. This study aimed to describe an international collaborative initiative to establish a semantically equivalent linguistic version of the EA-QOL questionnaires in 12 new countries. The 24-item EA-QOL questionnaire was translated into the target languages and the translated questionnaire was evaluated through cognitive debriefing interviews with children with EA aged 8–18 and their parents in each new country. Participants rated an item as to whether an item was easy to understand and sensitive/uncomfortable to answer. They could choose not to reply to a non-applicable/problematic item and provide open comments. Data were analyzed using predefined psychometric criteria; item clarity ≥80%, item sensitive/uncomfortable to answer ≤20%, item feasibility(missing item responses ≤5%). Decision to improve any translation was made by native experts–patient stakeholders and the instrument developer. Like in Sweden and Germany, all items in the cross-cultural analysis of child self-report (ntot = 82, 4–10 children/country) met the criteria for item clarity in all 12 new countries, and in parent-report (ntot = 86, 5–10 parents/country) in 8/12 countries. All items fulfilled the criteria for sensitive/uncomfortable to answer (child-report 1.2–9.9%; parent-report 0–11.6%) and item feasibility. Poor translations were resolved. Hence, this study has established semantically equivalent linguistic versions of the EA-QOL questionnaire for use in children aged 8–18 with repair of EA in and across 14 countries.
Induction of Endoplasmic Reticulum Stress by Prodigiosin in Yeast Saccharomyces cerevisiae
Authors: Nguyen Sy Le Thanh , Nguyen Thi Hien Trang , Do Thi Tuyen , Nguyen Thi Thao , Le Thanh Hoang , Nguyen Thi Anh Tuyet , Kimata Yukio
Published: February 2024

Prodigiosin, a red pigment produced by numerous bacterial species, exerts various antibiotic effects on prokaryotic and eukaryotic organisms. For instance, human carcinoma cell lines appear to suffer from endoplasmic reticulum (ER) stress in the presence of prodigiosin. Here, we demonstrated that prodigiosin also triggers the unfolded-protein response (UPR), which is a cytoprotective response against ER stress, in yeast Saccharomyces cerevisiae. An S. cerevisiae mutant carrying a UPR-deficient mutation was hypersensitive to prodigiosin. Our observations cumulatively indicate that protein folding in the ER is impaired by prodigiosin, illustrating a new mode of action.
Enhancing Sulfate Erosion Resistance in Ultra-High-Performance Concrete through Mix Design Optimization Using the Modified Andreasen and Andersen Method
Authors: Wang Guan , Chen Wenlin , Shen Xiangyu , Ren Xin , Niu Jiawei , Pan Sihang , Huang Yifan , Wu Jinliang
Published: February 2024

This study presents an in-depth investigation into optimizing the mix design of ultra-high-performance concrete (UHPC) for enhanced sulfate erosion resistance, utilizing the modified Andreasen and Andersen (MAA) method. By testing the mechanical properties and slump flow of UHPC, it was determined that the optimal W/B = 0.2, and the best volume content of steel fibers is 2%. Through long-term tests lasting 360 days on three groups of UHPC specimens under different curing conditions, their mass loss, compressive strength corrosion resistance coefficient, surface appearance, and erosion layer thickness were tested. The results indicate that under sulfate attack, the mass and compressive strength corrosion resistance coefficients of UHPC specimens showed a trend of first increasing and then decreasing, due to the formation and expansion of ettringite and gypsum. The thickness of the erosion layer increases over time. By 360 days, the internal damage caused by sulfate attack is about twice as severe as it was after 60 days. However, the addition of steel fibers was found to effectively mitigate these effects, reducing mass loss and preserving the structural integrity of UHPC.
Enhanced Indoor Conversion Efficiency of Dye-Sensitized Solar Cells by Optimizing Ball-Milling Process of TiO2 Paste
Authors: Ursu Daniel , Casut Cristian , Albulescu Daiana , Vajda Melinda , Mosoarca Cristina , Miclau Marinela
Published: February 2024

The rapid spread of the Internet of Things (IoT) along with the development of innovative low-power electronic devices has also driven the development of indoor photovoltaics. In this paper, we propose a simple and economically feasible solution that can improve the efficiency of dye-sensitized solar cells (DSSCs) under indoor light conditions by ~112%, without requiring a complex TiO2 photoanode architecture or the design of new dyes. The ball milling process of the TiO2 paste was optimized for indoor light conditions for the first time, both in terms of efficiency and production costs, by developing a rapid preparation method that can be used industrially for the application of DSSCs. A simple use of 12 mm diameter balls caused beneficial structural modifications, decreasing the size of the crystallites, and leading to a high OH generation on the TiO2 surface responsible for the improvement of energy conversion efficiency.
Physically Informed Deep Learning Technique for Estimating Blood Flow Parameters in Four-Vessel Junction after the Fontan Procedure
Authors: Isaev Alexander , Dobroserdova Tatiana , Danilov Alexander , Simakov Sergey
Published: February 2024

This study introduces an innovative approach leveraging physics-informed neural networks (PINNs) for the efficient computation of blood flows at the boundaries of a four-vessel junction formed by a Fontan procedure. The methodology incorporates a 3D mesh generation technique based on the parameterization of the junction’s geometry, coupled with an advanced physically regularized neural network architecture. Synthetic datasets are generated through stationary 3D Navier–Stokes simulations within immobile boundaries, offering a precise alternative to resource-intensive computations. A comparative analysis of standard grid sampling and Latin hypercube sampling data generation methods is conducted, resulting in datasets comprising 1.1×104 and 5×103 samples, respectively. The following two families of feed-forward neural networks (FFNNs) are then compared: the conventional “black-box” approach using mean squared error (MSE) and a physically informed FFNN employing a physically regularized loss function (PRLF), incorporating mass conservation law. The study demonstrates that combining PRLF with Latin hypercube sampling enables the rapid minimization of relative error (RE) when using a smaller dataset, achieving a relative error value of 6% on the test set. This approach offers a viable alternative to resource-intensive simulations, showcasing potential applications in patient-specific 1D network models of hemodynamics.
Effects of Dipentaerythritol and Cellulose as Additives on the Morphology of Pentaerythritol Crystals
Authors: Wei Wang , Li Yangguang , Tian Ningning , Xie Tian , Nie Dengpan , Li Hongyan , Quan Hongdong , Yang Xiuguo , Ye Luqian , Li Xiaohe , Li Kangli , Gao Ye
Published: February 2024

The crystal habit of pentaerythritol (PE) crystals is usually rod-shaped, which may lead to low bulk density and bad flowability compared with low aspect ratio crystals. In this study, dipentaerythritol (DPE), methylcellulose (MC), and hydroxypropyl methylcellulose (HPMC) were selected as additives to modify the morphology of PE crystals. In the presence of DPE, the bulk density of PE crystals was improved, and the aspect ratio was decreased. The modified attachment energy (AE) model was conducted to analyze changes in PE crystal habits in the presence of DPE, which characterizes the intensity of the interaction between DPE molecules and PE crystal faces. Spherical pentaerythritol crystals can be successfully prepared by adding MC and HPMC solution, and the formation mechanism can be divided into five steps.
Hybrid Joining of Dissimilar Thin Metallic Sheets—Mechanical Joining and Adhesive Bonding
Authors: Guzanová Anna , Draganovská Dagmar , Brezinová Janette , Tomáš Miroslav , Veligotskyi Nikita , Kender Štefan
Published: February 2024

This paper deals with joining dissimilar materials using thermal drilling technology as well as the combination of thermal drilling and adhesive bonding. The base materials for the experimental work were deep-drawn low-carbon steel DC04, HSLA steel TL 1550-220 + Z, and structural aluminum alloy EN AW-6082 T6 (AlSi1MgMn). The geometry of the formed joints was tested metallographically as the load-bearing shear capacity under the tensile shear test of single-lapped joints and the resistance of the joints against corrosion-induced disbonding in a climate chamber. The energy dissipated by the joints up to fracture was calculated from the load–displacement curves. The hybrid joints were compared with the bonded joints with the same overlap area in terms of the load-bearing capacity and energy dissipated at joint failure. The hybrid joints formed by thermal drilling and adhesive bonding with a rubber-based adhesive confirmed the synergistic effect—the adhesive provides the high load-bearing capacity of the joint, and the bushing formed by thermal drilling increases the dissipated energy of the joint at failure. The exposure of the joints in the climatic chamber did not cause a relevant reduction in the characteristics of the joints.
The Features and Treatment Effects on Keratoepitheliopathy for Meibomitis-Related Keratoconjunctivitis
Authors: Sonomura Yukiko , Yokoi Norihiko , Komuro Aoi , Kato Hiroaki , Sotozono Chie
Published: February 2024

Meibomitis-related keratoconjunctivitis (MRKC) is characterized by meibomitis with corneal epithelial abnormalities, and can be divided into two types: MRKC accompanied with phlyctenular keratitis, and MRKC accompanied with keratoepitheliopathy that is similar to superficial punctate keratopathy (SPK). The purpose of this retrospective study was to investigate the characteristic features of keratoepitheliopathy and treatment outcomes for MRKC. This study involved 27 eyes of 18 MRKC patients (3 males and 15 females). National Eye Institute (NEI) scores and visual acuity were compared at pre and post treatment. All subjects were treated with a small-dose administration of clarithromycin. Keratoepitheliopathy characteristic to MRKC, yet different in appearance from SPK, was noted in 24 of the 27 eyes. Fluorescein staining revealed granular epithelial lesions generally larger than SPK that coexisted with small dark spots. In 17 eyes, keratoepitheliopathy was located within the pupillary zone, and the visual acuity in 12 eyes was less than 1.0. Our findings showed significant improvement in the NEI score in MRKC (p < 0.0001) and in visual acuity (p = 0.0157) post treatment, and the characteristic features of keratoepitheliopathy in MRKC that are often associated with decreased visual acuity were elucidated. The treatment of clarithromycin was found to be effective for MRKC with keratoepitheliopathy.
Clinical Interpretation of Serum Troponin in the Era of High-Sensitivity Testing
Authors: Maayah Marah , Grubman Scott , Allen Stephanie , Ye Zachary , Park Dae Yong , Vemmou Evangelia , Gokhan Ilhan , Sun Wendy W. , Possick Stephen , Kwan Jennifer M. , Gandhi Parul U. , Hu Jiun-Ruey
Published: February 2024

Cardiac troponin (Tn) plays a central role in the evaluation of patients with angina presenting with acute coronary syndrome. The advent of high-sensitivity assays has improved the analytic sensitivity and precision of serum Tn measurement, but this advancement has come at the cost of poorer specificity. The role of clinical judgment is of heightened importance because, more so than ever, the interpretation of serum Tn elevation hinges on the careful integration of findings from electrocardiographic, echocardiographic, physical exam, interview, and other imaging and laboratory data to formulate a weighted differential diagnosis. A thorough understanding of the epidemiology, mechanisms, and prognostic implications of Tn elevations in each cardiac and non-cardiac etiology allows the clinician to better distinguish between presentations of myocardial ischemia and myocardial injury—an important discernment to make, as the treatment of acute coronary syndrome is vastly different from the workup and management of myocardial injury and should be directed at the underlying cause.
Pathways to Prosperity: Navigating Post-Stagnation Growth and Revitalizing Business
Authors: Spitsin Vladislav , Vuković Darko B. , Ryzhkova Marina , Leonova Victoria
Published: February 2024

This study examines the ways in which firms recover from stagnation or sales decline, with a focus on two key aspects: traditional high-growth companies and growth restarts within the framework of organizational life cycle theory. Analyzing a dataset of 1883 Russian firms from 2013 to 2021, this research employs logistic regression to identify factors that promote growth. These factors include the youth of the firm, investment intensity, and significant sales drops during periods of stagnation. The study introduces a new economic category, termed ‘restarting growth’, which signifies a firm’s sustained expansion following an extended period of stagnation. This category is crucial for identifying factors that increase the likelihood of a company transitioning to growth after prolonged stagnation or production downturn. The findings of this study reveal that firms that are younger, invest more intensively in fixed capital, and have experienced a larger sales drop during a period of stagnation are more likely to transition to growth. These results are juxtaposed with the growth factors characteristic of traditional high-growth companies, as well as with the theoretical approaches explaining growth restarts within the framework of organizational life cycle theory. Such distinctions are pivotal both for academic understanding and practical applications in discerning how companies rebound from crises. Moreover, the research identifies several highly significant factors—indicators that can assist investors in selecting promising firms for financing.
Food Inflation Examination through the Dynamic Nexus between Olive Oil and Substitutes
Authors: Kyriazis Nikolaos A.
Published: February 2024

This study provides insights into food inflation by investigating the dynamic interconnectedness of the prices of olive oil, soybean oil, sunflower oil, and palm oil. Using data from January 1990 to October 2023, averaged dynamic and extended joint connectedness analyses are conducted by employing the innovative Time-Varying Parameter Vector Autoregressive (TVP-VAR) methodology. The findings reveal that olive oil presents a low connection with substitute oils and generates net spillover effects, especially at the onset of COVID-19 but also at later stages and during the Russia–Ukraine war. Palm oil transmits effects on the system of oils before the Global Financial Crisis (GFC) but renders a net receiver afterward, while sunflower oil follows the opposite way. Systemic connectedness is the highest during the GFC and remains elevated during QE-tapering. It slightly increases during COVID-19 outbursts and illustrates higher spikes when the Russia–Ukraine conflict begins. These linkages are even stronger among only the substitute oils.
Tracing Progress in Children’s Executive Functioning and Language Abilities Related to Reading Comprehension via ExeFun-READ Intervention
Authors: Kovalčíková Iveta , Veerbeek Jochanan , Vogelaar Bart , Klimovič Martin , Gogová Eva
Published: February 2024

One important internal factor influencing reading comprehension is a child’s executive functioning. The primary objective of this paper is to evaluate the effectiveness of a cognitive stimulation program, ExeFun-READ (a program focusing on executive functioning stimulation via the L1 (Slovak language) curriculum with a specific focus on enhancing reading comprehension). The program is explicitly based on the assumed bi-directional relationship between executive functioning and language abilities related to reading comprehension. The program is domain-specific; the curriculum of L1 (Slovak) is a curricular area in which cognitive mediation occurs. The study will investigate whether the domain-specific ExeFun-READ intervention had a positive effect on children’s executive functioning and language subcomponents of reading comprehension. Keeping in mind ecological validity, ExeFun-READ was designed primarily for educational purposes, specifically professional tutoring for low-performing students. The intervention consists of 30 units; each unit lasts for 45–60 min. A stimulation unit approximates a teaching unit rather than a clinical experimental intervention. In total, 151 low-performing students attending grade four from seven elementary schools took part in the project. The study employs a pre-test–training–post-test design with three conditions: experimental, active control, and passive control. In the current study, the intervention led to improved language abilities related to reading comprehension. Significant improvements were found in vocabulary (semantic knowledge), completion of sentences (syntactic knowledge), and classification of terms (verbal fluency and inferencing) in the group of children that received the ExeFun-READ intervention. In terms of executive functioning, the improvement only extended to switching fluency.
Cascaded Multi-Input Single-Output Boost Inverter for Mismatch Mitigation at PV Submodule Level
Authors: Alharbi Yousef , Darwish Ahmed , Ma Xiandong
Published: February 2024

Mismatched power generation is a serious issue in PV systems, resulting from unequal power generation between PV components. Solutions have been proposed to reduce or eliminate the mismatch concern. One practical strategy is individually harvesting the maximum power from each PV component; the more distributed MPPT is applied to a finer level, the more power can be obtained. This study proposes three-input single-output boost converters that are employed to effectively increase PV power generation and significantly reduce mismatch issues between the PV submodule (PV SM). Each boost converter will be controlled to harvest the maximum power from a group of PV cells inside a single PV module. The outputs of the three boost converters are connected in series to provide higher output voltage for grid integration. The cascaded power converters are linked with a forwarding diode to provide a protection feature for the system and prevent the reverse current from harming the PV module. On the grid side, a single-phase Voltage Source Inverter (VSI) is used to convert the DC power from the PV module to sinusoidal AC power. The performance of the suggested inverter has been confirmed through experimental tests.
Feed Error Prediction and Compensation of CNC Machine Tools Based on Whale Particle Swarm Backpropagation Neural Network
Authors: Fang Wenkang , Qian Yingping , Yu Zhongquan , Zhang Dongqiao
Published: February 2024

Current modeling methods of machine tool feed error are challenging to meet the demand of high-precision machining when facing complex machining conditions. To enhance the model’s predictive accuracy and the effectiveness of actual compensation, the Whale Particle Swarm Optimization (WPSO) algorithm is proposed to optimize the Backpropagation Neural Network (BPNN). Subsequently, the optimized network incorporates screw elongation and feed position as inputs to establish a feed-error prediction model. Ultimately, the established model was compared with other models and applied to real-time compensation experiments. The research results show that the proposed prediction model outperforms the BPNN model, the particle swarm-optimized BPNN model, and the whale-optimized BPNN model in various indicators. The accuracy of the prediction model was 93.12%, and the errors ranged from −3.80 μm to 4.57 μm with an average error of −0.30 μm. Under different operating conditions, the maximum backward and forward errors are reduced by 33.21% and 87.21%, and the average backward and forward errors are reduced by 57.15% and 84.37%, respectively. The error range is reduced by 67.41%. Beyond elevating prediction accuracy and compensation efficacy, the proposed model offers robust theoretical guidance for practical production.
A Memristor Neural Network Based on Simple Logarithmic-Sigmoidal Transfer Function with MOS Transistors
Authors: Mladenov Valeri , Kirilov Stoyan
Published: February 2024

Memristors are state-of-the-art, nano-sized, two-terminal, passive electronic elements with very good switching and memory characteristics. Owing to their very low power usage and a good compatibility to the existing CMOS ultra-high-density integrated circuits and chips, they are potentially applicable in artificial and spiking neural networks, memory arrays, and many other devices and circuits for artificial intelligence. In this paper, a complete electronic realization of an analog circuit model of the modified neural net with memristor-based synapses and transfer function with memristors and MOS transistors in LTSPICE is offered. Each synaptic weight is realized by only one memristor, providing enormously reduced circuit complexity. The summing and scaling implementation is founded on op-amps and memristors. The logarithmic-sigmoidal activation function is based on a simple scheme with MOS transistors and memristors. The functioning of the suggested memristor-based neural network for pulse input signals is evaluated both analytically in MATLAB-SIMULINK and in the LTSPICE environment. The obtained results are compared one to another and are successfully verified. The realized memristor-based neural network is an important step towards the forthcoming design of complex memristor-based neural networks for artificial intelligence, for implementation in very high-density integrated circuits and chips.
A Novel Adaptive Indoor Positioning Using Mobile Devices with Wireless Local Area Networks
Authors: Huang Yung-Fa , Hsu Yi-Hsiang , Lin Jen-Yung , Chen Ching-Mu
Published: February 2024

In this paper, mobile devices were used to estimate the received signal strength indicator (RSSI) of wireless channels with three wireless access points (APs). Using the RSSI, the path loss exponent (PLE) was adapted to calculate the estimated distance among the test points (TPs) and the APs, through the root mean square error (RMSE). Moreover, in this paper, the proposed adaptive PLE (APLE) of the TPs was obtained by minimizing the positioning errors of the PLEs. The training samples of RSSI were measured by TPs for 6 days, and different surge processing methods were used to obtain APLE and to improve the positioning accuracy. The surge signals of RSSI were reduced by the cumulated distribution function (CDF), hybrid Kalman filter (KF), and threshold filtering methods, integrating training samples and APLE. The experimental results show that with the proposed APLE, the position accuracy can be improved by 50% compared to the free space model for six TPs. Finally, dynamic real-time indoor positioning was performed and measured for the performance evaluation of the proposed APLE models. The experimental results show that, the minimum dynamic real-time positioning error can be improved to 0.88 m in a straight-line case with the hybrid method. Moreover, the average positioning error of dynamic real-time indoor positioning can be reduced to 1.15 m using the four methods with the proposed APLE.
Oxidative Liquefaction, an Approach for Complex Plastic Waste Stream Conversion into Valuable Oxygenated Chemicals
Authors: Mumtaz Hamza , Werle Sebastian , Muzyka Roksana , Sobek Szymon , Sajdak Marcin
Published: February 2024

Various waste streams including municipal solid waste (MSW), polymer waste from personal protective equipment (PPE) used in medical fields, and composite waste from wind turbine blades (WTBs) demand modern waste management and recycling approaches. Ultimate and proximate analysis of mentioned samples revealed a higher content of carbon—28.2 ± 8.0, 80.1 ± 2.3, and 50.3 ± 2.3, respectively—exhibiting sufficient potential to be converted into secondary carbon-based compounds. For this purpose, oxidative liquefaction of selected waste materials was carried out following a detailed experimental plan, a centred composite design for WTBs, and a central composite face-centred plan for MSW and PPEs. Temperature, pressure, oxidant concentration, reaction time, and waste-to-liquid ratio were the parameters of key interest, and their values were tested at a range of 200–350 °C, 20–40 bar, 15–60%, 30–90 min, and 3–25%, respectively, depending upon the type of waste. As a result, total polymer degradation (TPD) was recorded for three types of waste and the results were satisfactory, encouraging the decomposition of primary waste in liquid oxygenated chemical compounds (OCCs). Gas Chromatography with Flame Ionisation Detection (GC-FID) helped us quantify the number of OCCs for each waste sample. Energy consumption during the process was also recorded and optimisation of the experimental plan based on maximum TPD and OCCs yields against the minimum energy consumption was performed to make the process tech-economic.
Estimation of an Extent of Sinusoidal Voltage Waveform Distortion Using Parametric and Nonparametric Multiple-Hypothesis Sequential Testing in Devices for Automatic Control of Power Quality Indices
Authors: Kulikov Aleksandr , Ilyushin Pavel , Sevostyanov Aleksandr , Filippov Sergey , Suslov Konstantin
Published: February 2024

Deviations of power quality indices (PQI) from standard values in power supply systems of industrial consumers lead to defective products, complete shutdown of production processes, and significant damage. At the same time, the PQI requirements vary depending on the industrial consumer, which is due to different kinds, types, and composition of essential electrical loads. To ensure their reliable operation, it is crucial to introduce automatic PQI control devices, which evaluate the extent of distortion of the sinusoidal voltage waveform of a three-phase system. This allows the power dispatchers of grid companies and industrial enterprises to quickly make decisions on the measures to be taken in external and internal power supply networks to ensure that the PQI values are within the acceptable range. This paper proposes the use of an integrated indicator to assess the extent of distortion of the sinusoidal voltage waveform in a three-phase system. This indicator is based on the use of the magnitude of the ratio of complex amplitudes of the forward and reverse rotation of the space vector. In the study discussed, block diagrams of algorithms and flowcharts of automatic PQI control devices are developed, which implement parametric and nonparametric multiple-hypothesis sequential analysis using an integrated indicator. In this case, Palmer’s algorithm and the nearest neighbor method are used. The calculations demonstrate that the developed algorithms have high speed and high performance in detecting deviations of the electrical power quality.
Analysis and Design of Independent DC Bus Structure Multiport Power Electronic Transformer Based on Maximum Power Transmission Capability of Low-Voltage DC Ports
Authors: Li Junchi , Wu Junyong , Xiong Fei
Published: February 2024

Owing to the diverse connection configurations of dual active bridge converters, a multiplicity of low-voltage DC port structures are anticipated to emerge in the independent DC bus structure multiport power electronic transformer (IDBS-MPET). An inadequate low-voltage DC port structure exacerbates the power imbalance in IDBS-MPET, presenting a risk of overmodulation even when transmitting relatively low levels of power. To overcome this limitation, a design scheme of IDBS-MPET topology based on the maximum power transmission capability of the low-voltage DC ports is proposed in this paper. Three topology design rules are derived from the maximum power transmission capability results of more than 80 typical IDBS-MPET topologies. The symmetrical triple cross-phase connection structure, the symmetrical double cross-phase connection structure and the single-phase connection structure are sequentially identified as the three most optimal structures of low-voltage DC ports. By employing the proposed design methodology, each low-voltage DC port achieves its maximum power transfer capability relative to other configurations. The effectiveness of the proposed design scheme is validated by an optimal designed IDBS-MPET topology with six low-voltage DC ports.
Critical Inertia Calculation Method of Generators Using Energy Balance Condition in Power System
Authors: Yang Jae-Young , Song Yu Hoon , Kook Kyung Soo
Published: February 2024

Critical inertia can be defined as the minimum kinetic energy stored in generators that should be kept for maintaining the frequency stability of the power system. As the frequency control performance of the power system is maintained according to its control criterion, during the inertia response time frame, the expected energy imbalance can be calculated by accumulating the imbalanced power caused by the credible contingency and calculating the available inertia response by considering the allowable operating limit of the frequency. Since the frequency control criterion can be met when the available inertia response becomes larger than the expected energy imbalance, the critical inertia can be calculated by the kinetic energy of the generators, of which the available inertia response is equal to the expected energy imbalance due to the contingency. With this in mind, this paper derives the energy balance condition for the frequency stability in the inertia response time frame based on the frequency control criterion and calculates the minimum inertia, which should be kept in the generators from the energy balance condition for meeting the criterion. In addition, the effectiveness of the proposed method is verified through various case studies employing Korean power systems.
Agritourism Facilities in the Era of the Green Economy: A Combined Energy Audit and Life Cycle Assessment Approach for the Sustainable Regeneration of Rural Structures
Authors: Bigiotti Stefano , Costantino Carlo , Marucci Alvaro
Published: February 2024

This paper aims to investigate potential strategies to reduce energy consumption and environmental impacts of a recently converted rural complex into an agri-spa in a high environmental value area within the province of Viterbo (Italy). Actual operational data on appliances, climate, and energy consumption are employed for the energy audit. While this analysis generally provides energy-saving solutions, such options are not examined for their life cycle environmental impacts. The current article is based on the experimentation of a consolidated methodological approach in the scientific literature, integrating the energy audit, life cycle assessment (LCA), and economic analysis (Life Cycle Cost) to assess a series of energy-efficiency measures designed for the new wellness centre function. The combined use of these well-established procedures provides a comprehensive assessment of intervention scenarios for a particularly energy-intensive type of case study, not yet widely documented in the literature. The results reveal that energy consumption related to heating/cooling is marginal compared to the actual electrical consumption in the specific case study. Therefore, the most efficient scenarios involve installing photovoltaic systems and replacing gas boilers with high-efficiency heat pumps, especially with economically advantageous insulation. This leads to a 51% reduction in energy consumption and an 81% decrease in heating, DHW, and electricity costs.
ANN-LSTM-A Water Consumption Prediction Based on Attention Mechanism Enhancement
Authors: Zhou Xin , Meng Xin , Li Zhenyu
Published: February 2024

To reduce the energy consumption of domestic hot water (DHW) production, it is necessary to reasonably select a water supply plan through early predictions of DHW consumption to optimize energy consumption. However, the fluctuations and intermittence of DHW consumption bring great challenges to the prediction of water consumption. In this paper, an ANN-LSTM-A water quantity prediction model based on attention mechanism (AM) enhancement is improved. The model includes an input layer, an AM layer, a hidden layer, and an output layer. Based on the combination of artificial neural network (ANN) and long short-term memory (LSTM) models, an AM is incorporated to address the issue of the traditional ANN model having difficulty capturing the long-term dependencies, such as lags and trends in time series, to improve the accuracy of the DHW consumption prediction. Through comparative experiments, it was found that the root mean square error of the ANN-LSTM-A model was 15.4%, 13.2%, and 13.2% lower than those of the ANN, LSTM, and ANN-LSTM models, respectively. The corresponding mean absolute error was 17.9%, 11.5%, and 8% lower than those of the ANN, LSTM, and ANN-LSTM models, respectively. The results showed that the proposed ANN-LSTM-A model yielded better performances in predicting DHW consumption than the ANN, LSTM, and ANN-LSTM models. This work provides an effective reference for the reasonable selection of the water supply plan and optimization of energy consumption.
Construction of a Small-Sized Simplified Chemical Kinetics Model for the Simulation of n-Propylcyclohexane Combustion Properties
Authors: Saraee Hossein S. , Hughes Kevin J. , Pourkashanian Mohamed
Published: February 2024

The development of a compact mechanism has made a great contribution to work on the combustion of hydrocarbon species and facilitates the investigations on chemical kinetics and computational fluid dynamics (CFD) studies. N-propylcyclohexane (NPCH) is one of the important components for jet, diesel, and gasoline fuels which needs a reliable compact reaction kinetics mechanism. This study aims to investigate the construction of a well-validated mechanism for NPCH with a simplified chemical kinetics model that delivers a good prediction ability for the key combustion parameters in a wide range of conditions (temperatures, pressures, and equivalence rates). The NPCH reaction kinetic mechanism was constructed with the aid of a coupling process, simplification process, rate modification, and a combination of standard reduction methods. The model includes a simplified sub-mechanism with 16 species and 58 reactions and a semi-detailed core mechanism with 56 species and 390 reactions. Two key parameters including ignition delay time and laminar flame speed are simulated by the use of ANSYS Chemkin-Pro. The simulation results for these parameters are validated against the available data in the literature, and the results show a good agreement compared to the experimental data over a wide range of conditions covering low to high temperatures at different pressures and equivalence ratios.
Production of CH4/C3H8 (85/15 vol%) Hydrate in a Lab-Scale Unstirred Reactor: Quantification of the Promoting Effect Due to the Addition of Propane to the Gas Mixture
Authors: Gambelli Alberto Maria , Gigliotti Giovanni , Rossi Federico
Published: February 2024

By itself, propane is capable to form hydrates at extremely contained pressures, if compared with the values typical of “guests” such as methane and carbon dioxide. Therefore, its addition in mixtures with gases such as those previously mentioned is expected to reduce the pressure required for hydrate formation. When propane is mixed with carbon dioxide, the promoting effect cannot be observed since, due to their molecular size, these two molecules cannot fit in the same unit cell of hydrates. Therefore, each species produces hydrates independently from the other, and the beneficial effect is almost completely prevented. Conversely, if propane is mixed with methane, the marked difference in size, together with the capability of methane molecules to fit in the smaller cages of both sI and sII structures, will allow to form hydrates in thermodynamic conditions lower than those required for pure methane hydrates. This study aims to experimentally characterize such a synergistic and promoting effect, and to quantity it from a thermodynamic point of view. Hydrates were formed and dissociated within a silica porous sediment and the results were compared with the phase boundary equilibrium conditions for pure methane hydrates, defined according to experimental values available elsewhere in the literature. The obtained results were finally explained in terms of cage occupancy.
Research on Analysis and Suppression Methods of the Bearing Current for Electric Vehicle Motor Driven by SiC Inverter
Authors: Yang Mingliang , Cheng Yuan , Du Bochao , Li Yukuan , Wang Sibo , Cui Shumei
Published: February 2024

The silicon carbide (SiC) inverter brings great advantages to the motor drive systems of new energy vehicles; however, severe challenges to the bearings also happen. The high dc bus voltage and switching frequency of SiC inverter can increase the discharge frequency and energy when the bearing grease film collapses. As a result, the bearing suffers severe electric corrosion, and the service life of the motor drive system can be shortened. In this paper, the characteristics of common-mode voltage and bearing voltage are analyzed, firstly under space vector pulse width modulation (SVPWM). After that, the common-mode equivalent circuit model of the motor drive system is established. The frequency characteristics of bearing voltage are revealed, and the safe working area is determined. Then, the frequency characteristics of bearing voltage and current are verified based on IGBT and SiC inverters in experiments. After that, by designing a common-mode filter, the bearing voltage and current are significantly attenuated. Furthermore, the active zero state PWM (AZSPWM) is adopted to reduce the common-mode voltage from the inverter. At the same time, combined with the common-mode filter, the bearing voltage and current are further reduced. The experimental results show that the switching frequency has a decisive effect on the amplitude of bearing voltage and current. The bearing voltage can be attenuated to around half of the reference bearing voltage by using the common-mode filter and AZSPWM strategy, respectively. The combination of the common-mode filter and AZSPWM strategy can reduce the bearing voltage to around one-fourth of the reference bearing voltage, which can effectively reduce the breakdown time and discharge energy of the grease oil film.
Air Equalizing Mechanism in Cooling Performance Improvement of Vertical Delta-Type Radiators
Authors: Chen Tiefeng , Zhao Qian , Zhang Yaoming , Wang Chengjun , Li Kaiming , Li Shixing , Quan Longtao , Zhao Yuanbin
Published: February 2024

Based on the design and measured data of one actual tower, a three-dimensional numerical model for a natural draft dry cooling tower (NDDCT) was created and validated under constant heat load. This enabled the performance improvement mechanism of air equalizing on vertical delta-type radiators (VDRs) to be clarified by detailed analysis of key parameters, such as the exit water temperature, heat transfer coefficient, and mass airflow. Under the impact of typical ambient crosswind, all VDRs were retrofitted with air-side-equalizing devices. It was found that the exit water temperatures of the whole NDDCT decreased by 0.865 °C, 0.593 °C and 0.186 °C under the studied ambient crosswind speeds of 2.5 m/s, 4 m/s and 12 m/s, respectively. The performance improvement mechanism of air-side equalizing was investigated for three VDRs, which were located on the upwind, tower lateral, and downwind sides under crosswind impacts. Besides the studied VDRs, the performance of the neighboring VDRs behind them was also improved by the optimized aerodynamic field and the reduced hot wind recirculation around them. In addition, the average heat transfer coefficients of the VDRs were enhanced, which could lay the foundation for improving the cooling performance of thermodynamic devices with VDRs.
Modeling of Linearized Generator Inertia Constraints for Unit Commitment
Authors: Kim Sung-Eun , Chun Yeong-Han
Published: February 2024

This study presents a novel approach to modeling linearized inertia constraints of generators, considering frequency stability, and applies it to the unit commitment (UC). Specifically, we modeled the average rate of change of frequency (RoCoF) constraint and the minimum frequency constraint using the analytical expression derived from the reduced frequency response (RFR) model. We also considered the load-damping constant as a variable. As the power system has different nonlinear characteristics according to its operating status, the system can be expressed as several different systems. Each subsystem, with its own properties at a given operating point, is modeled as a single-machine system, categorized by pumped storage hydropower (PSH) status. The minimum frequency of each subsystem is determined by its individual machine time constant. We incorporated an additional constraint to ensure the quasi steady-state performance of frequency. This constraint can be omitted when it is not necessary. The proposed concepts have been validated on the Korean Power System. The UC, with the proposed inertia constraints, can secure system inertia and primary frequency response (PFR) that satisfies frequency stability. Our proposed method is more efficient in securing inertia and PFRs and more economical in terms of generation cost compared to existing methods.
Biomass Production and Metal Remediation by Salix alba L. and Salix viminalis L. Irrigated with Greywater Treated by Floating Wetlands
Authors: Almuktar Suhad A. A. A. N. , Abed Suhail N. , Scholz Miklas
Published: February 2024

As an alternative wood source for biochar and a cost-effective renewable energy source, sustainable biomass production based on fast-growing willows irrigated with treated wastewater has been explored. Salix alba L. and Salix viminalis L. were selected for assessment of their potentially high woody biomass productivity and phytoremediation efficiency when irrigated with greywater treated by floating treatment wetlands. Both Salix species produced significantly (p < 0.05) high woody biomass in the second harvest, with a significantly higher fresh woody biomass weight with higher water content (53%) for S. viminalis compared to S. alba. The dry biomass weight of S. alba was greater than of S. viminalis at the first harvest. The element accumulations in substrates changed significantly after irrigation, with greywater compared to the raw substrate following this order: Mg > Fe > Al > Cr > Mn > Cd > Cu > B. Element concentrations accumulated in twigs of S. alba following this order: Ca > Mg > Na > Mn > Zn > Fe > Al > Cd > Cu > Cr > Ni > B, but for S. viminalis the order was Ca > Mg > Mn > Zn > Na > Fe > Al > Cd > Cu > Ni > Cr > B. The accumulations of Al, B, Ca, Fe, Mg, Mn, and Ni were significantly greater in S. alba leaves compared to their twigs, which showed significantly high accumulations of Na and Zn. The accumulations of Al, B, Ca, Fe, Mg, Mn, and Na were significantly greater in S. viminalis leaves compared to their twigs.
Differences in the Volatile Profile of Apple Cider Fermented with Schizosaccharomyces pombe and Schizosaccharomyces japonicus
Authors: Ferremi Leali Nicola , Salvetti Elisa , Luzzini Giovanni , Salini Andrea , Slaghenaufi Davide , Fusco Salvatore , Ugliano Maurizio , Torriani Sandra , Binati Renato L.
Published: February 2024

In this study, two strains of Schizosaccharomyces pombe (NCAIM Y01474T and SBPS) and two strains of Schizosaccharomyces japonicus (DBVPG 6274T, M23B) were investigated for their capacity to ferment apple juice and influence the volatile compounds of cider compared to Saccharomyces cerevisiae EC1118. The ethanol tolerance and deacidification capacity of Schizosaccharomyces yeasts could make them potential substitutes for the commonly used S. cerevisiae starter cultures. Despite different time courses (10–30 d), all strains could complete the fermentation process, and Schizosaccharomyces strains reduced the concentration of malic acid in the apple juice. Results indicated that each yeast exerted a distinctive impact on the volatile profile of the apple cider, giving final products separated using a principal component analysis. The volatile composition of the cider exhibited significant differences in the concentration of alcohols, esters, and fatty acids. Particularly, the flocculant strain S. japonicus M23B increased the levels of ethyl acetate (315.44 ± 73.07 mg/L), isoamyl acetate (5.99 ± 0.13 mg/L), and isoamyl alcohol (24.77 ± 15.19 mg/L), while DBVPG 6274T incremented the levels of phenyl ethyl alcohol and methionol up to 6.19 ± 0.51 mg/L and 3.72 ± 0.71 mg/L, respectively. A large production of terpenes and ethyl esters (e.g., ethyl octanoate) was detected in the cider fermented by S. cerevisiae EC1118. This study demonstrates, for the first time, the possible application of S. japonicus in cider-making to provide products with distinctive aromatic notes”.
Application of Aqueous Two-Phase Systems with Thermoseparating Polymers (EOPO) as a Method for Extractive Fermentation with Neochloris oleoabundans
Authors: Garza-Chapa Ana Patricia , Ávila-Velasco Carlos Iván , González-Valdez José , Gómez-Loredo Alma
Published: February 2024

Extractive fermentation is an in situ method for the production and recovery of biomolecules of interest. Aqueous two-phase systems (ATPS) allow the product to be recovered in one phase of the system, reducing unit operations in the bioprocess. Thermosensitive polymers such as EOPOs are an interesting alternative to be applied in ATPS. In this work, different EOPOs were tested in an extractive fermentation strategy with the green microalgae Neochloris oleoabundans to provide a basis for future implementations of these systems in microalgae bioprocesses. Extractive fermentations were carried out with two EOPOs of different molecular weights (3900 and 12,000 g/mol) at concentrations of 10% and 15% (w/v). The microalga was incubated axenically under two different sets of conditions for 21 and 45 days, respectively. Cell counts were performed, and cell growth curves were obtained. Additionally, a semi-continuous and batch extractive fermentation assay was performed. The extractive fermentation with EOPO showed lower cell growth and a longer adaptation time of the microalgae in the fermentation, and EPS production yields of up to 8–23 g/L were obtained. Extractive fermentation is an interesting method to be implemented in microalgae cultures; however, further conditions need to be explored to achieve an appropriate bioprocess.