bluuebunny/crossref_metadata_2025 huggingface dataset:
Shedding Light on the Lifestyle and Participation of Portuguese Adolescents with Chronic Conditions—Data from the HBSC 2018 Study
Authors: Cerqueira Ana , Botelho Guedes Fábio , Gaspar Tania , Godeau Emmanuelle , Gaspar de Matos Margarida
Published: November 2022

Variables associated with lifestyle can constitute either risk or protective factors for the development and progression of chronic conditions (CC). This study intends to explore the differences between adolescents with and without CC and between adolescents whose school participation is affected/not affected by the existing CC with regard to variables related to lifestyle (i.e., sleep, physical activity, BMI, and leisure). In addition, it also intends to analyze the influence of these variables (i.e., CC and lifestyle) regarding the adolescents’ quality of life (QoL). This work is part of the Portuguese HBSC 2018 study. A total of 8215 adolescents participated (52.7% female), with an average age of 14.36 years (SD = 2.28). The results showed that the adolescents with CC and whose school attendance and participation are affected by their CC exhibit more sleep difficulties (i.e., they experience lower sleep quality and have a higher degree of sleepiness), higher BMI levels (i.e., higher values of overweight and obesity), less participation in leisure activities, and a lower perception of QoL. A higher perception of QoL is associated with school participation unaffected by the existing CC, sleeping well, a low level of sleepiness, a more frequent practice of physical activity, a lower BMI, and a greater involvement in leisure activities. Adolescent health and well-being are a prominent issue in terms of public policies, with behavior and lifestyle playing a significant role in this domain. This message needs to be reinforced in regard to families, educators, healthcare professionals, and public sector policies, particularly concerning students with CC.
Prevalence of Computer Vision Syndrome among School-Age Children during the COVID-19 Pandemic, Saudi Arabia: A Cross-Sectional Survey
Authors: Abuallut Ismail , Ajeebi Reham E. , Bahari Alanoud Y. , Abudeyah Manal A. , Alyamani Atheer A. , Zurayyir Atyaf J. , Alharbi Abdulkareem H. , Al Faqih Abdullah A. , Suwaydi Abdullatif Z. , Alqasemi Maram I. , Alnami Bushra A. , Al Zahrani Khaled Jamaan
Published: November 2022

Background: Computer vision syndrome (CVS) can be described as ocular-related symptoms that result from prolonged exposure and use of computers, smartphones, tablets, and other devices with digital displays. The main objective of this study was to investigate the prevalence of CVS among school-age children, the associated signs, risk factors, and the association between the disease before and during the COVID-19 pandemic in the Jazan region of Saudi Arabia. Methods: The study employed a descriptive cross-sectional research design. The targeted population was school-going children aged 6 to 18 in the Jazan region in the Southwest of Saudi Arabia. A sample of 440 participants was selected to represent the population under study. Data were collected using self-administered questionnaires. Sociodemographic characteristics were recorded, such as age, gender, education level, parents’ education, occupation, frequency, and intensity of eye symptoms if present. Results: Most of the participants were adolescents between 16 and 18 and at a high-school education level. According to the total symptoms score, the CVS prevalence was 35.4%. Prevalence of CVS significantly affects age, gender, and school level (p < 0.05 for all). A similar significant association was reported between the symptoms experienced before and during COVID-19 and the CVS (p < 0.05). Conclusion: A total of 407 adolescents aged 16–18 responded to the questionnaire (response rate of 92.5%; 407 out of 440). The study estimated the prevalence of CVS among school-going children in Jazan to be low. The main signs associated with CVS included headache, tearing, itchiness, blurred vision, eye redness, eye pain, and dryness. The attitude of children toward their health condition during the COVID-19 pandemic and the prevalence of CVS have a significant relationship.
Human Non-Hypertrophic Nonunion Tissue Contains Osteoblast Lineage Cells and E-BMP-2 Activates Osteogenic and Chondrogenic Differentiation
Authors: Yoshikawa Ryo , Fukui Tomoaki , Oe Keisuke , Kumabe Yohei , Oda Takahiro , Sawauchi Kenichi , Takase Kyohei , Yamamoto Yuya , Sakai Yoshitada , Kuroda Ryosuke , Niikura Takahiro
Published: November 2022

In this study, we examined the proliferation capability and osteogenic and chondrogenic differentiation potential of non-hypertrophic nonunion cells (NHNCs), and the effect of Escherichia coli-derived BMP-2 (E-BMP-2) on them. We enrolled five patients with non-hypertrophic nonunion. NHNCs isolated from nonunion tissue sampled during surgery were cultured, passaged, counted every 14 days, and analyzed. NHNCs were homogenous fibroblastic adherent cells and long-lived through at least 10 passages, with a slight decline. The cells were consistently positive for mesenchymal stem cell-related markers CD73 and CD105, and negative for the hematopoietic markers CD14 and CD45. NHNCs could differentiate into osteoblast lineage cells; however, they did not have strong calcification or sufficient chondrogenic differentiation capability. E-BMP-2 did not affect the proliferative capability of the cells but improved their osteogenic differentiation capability by increasing alkaline phosphatase activity and upregulating the gene expression of osterix, bone sialoprotein, and osteocalcin. E-BMP-2 enhanced their chondrogenic differentiation capability by upregulating the gene expression of aggrecan and collagen type II. We showed, for the first time, that NHNCs have the capacity to differentiate into osteoblast-lineage cells, although the chondrogenic differentiation potential was poor. Local application of E-BMP-2 with preservation of nonunion tissue is a potential treatment option for non-hypertrophic nonunion.
A Split-Ring Resonator-Loaded Honeycomb Sandwich Structure for Broadband Microwave Absorption
Authors: Zhao Yiming , Liu Qingwei , Xu Zhonghao , Ji Guoliang , Mo Ran
Published: November 2022

Split-ring resonators are excellent left-handed metamaterials for significant electromagnetic coupling behavior. In this work, a split-ring resonator prepared with Ni-doped zeolitic imidazolate framework-67/epoxy resin (ZIF-67/ER) was embedded in the top layer to optimize microwave absorption efficiency in the 2–4 GHz frequency band. The Ni-doped ZIF-67/epoxy resin served as the bottom layer to improve microwave absorption efficiency in the 4–8 GHz frequency band. Honeycomb with a conductive carbon black coating served as the middle layer to generate electromagnetic loss for the overall frequency band. Based on the composite structure integration technology, RL < −10 dB was realized under the oblique incidence of 0–70 degrees. Both simulation and experiments indicate that a split-ring resonator made of lossy material can be an effective strategy to broaden the effective absorption bandwidth and increase the corresponding structure’s insensitivity to polarization and the incidence angle of microwave.
Ancient Roman Mortars from Anfiteatro Flavio (Pozzuoli, Southern Italy): A Mineralogical, Petrographic and Chemical Study
Authors: Montesano Giovanna , Verde Maria , Columbu Stefano , Graziano Sossio Fabio , Guerriero Luigi , Iadanza Maria Laura , Manna Annalisa , Rispoli Concetta , Cappelletti Piergiulio
Published: November 2022

This research is based on the characterization of ancient mortars from the Anfiteatro Flavio (Pozzuoli) dating back to the 1st and 2nd century CE through a multi-analytical approach involving macroscopic, mineralogical, petrographic, and chemical investigations. The goal that has been set is to deepen knowledge about mortar mix design, the provenance of used raw materials, and secondary minerogenetic processes that have occurred within ancient Roman mortars. Results show that: (i) raw materials for mortar preparation have a local provenance, i.e., Phlegraean Fields area; (ii) mortars can be considered as hydraulic; (iii) calcite presence could be due to a non-complete calcination process, an improper slaking or to exposition of materials to the subaerial environment; (iv) gypsum is due to calcite sulfation process; (v) halite presence is due to marine aerosol exposition. The achieved information testifies that, for at least two centuries, Roman builders considered the identified mortar mix as optimal for their buildings, but also contributes to the understanding of their technical skills and represents an important first step to planning future restoration operations.
Improving User Privacy in Identity-Based Encryption Environments
Authors: Adams Carlisle
Published: November 2022

The promise of identity-based systems is that they maintain the functionality of public key cryptography while eliminating the need for public key certificates. The first efficient identity-based encryption (IBE) scheme was proposed by Boneh and Franklin in 2001; variations have been proposed by many researchers since then. However, a common drawback is the requirement for a private key generator (PKG) that uses its own master private key to compute private keys for end users. Thus, the PKG can potentially decrypt all ciphertext in the environment (regardless of who the intended recipient is), which can have undesirable privacy implications. This has led to limited adoption and deployment of IBE technology. There have been numerous proposals to address this situation (which are often characterized as methods to reduce trust in the PKG). These typically involve threshold mechanisms or separation-of-duty architectures, but unfortunately often rely on non-collusion assumptions that cannot be guaranteed in real-world settings. This paper proposes a separation architecture that instantiates several intermediate CAs (ICAs), rather than one (as in previous work). We employ digital credentials (containing a specially-designed attribute based on bilinear maps) as the blind tokens issued by the ICAs, which allows a user to easily obtain multiple layers of pseudonymization prior to interacting with the PKG. As a result, our proposed architecture does not rely on unrealistic non-collusion assumptions and allows a user to reduce the probability of a privacy breach to an arbitrarily small value.
Introducing Fuel Cell Application Using Sodium Vacancies in Hexagonal Wurtzite Structured ZnO Nanorods for Developing Proton–Ion Conductivity
Authors: Song Yixiao , Qin Jingwen , Li Lei , Mushtaq Naveed , Shah M. A. K. Yousaf , Xie Jun
Published: November 2022

Zinc oxide, a direct band gap semiconductor of ≥3.30 eV, is prevalent in potential requests for energy devices. The early-stage demonstration of ZnO provides a new method of developing high ionic conductivity in multifunctional semiconductors for electrolyte applications in ceramic fuel cells (CFCs). In the present work, we successfully synthesized Na-doped ZnO nanorods by a hydrothermal method and employed them as an electrolyte in CFCs. The synthesized Na-doped-ZnO nanorods showed an effective ionic conductivity of 8.75 × 10−2 S cm−1 along with an excellent power density of 609 mWcm−2 ± 5% when the fuel cell was operating at 550 °C. The enhanced ionic conductivity could be due to Na+ doping into Zn2+ and the high ionic radius of Na ions producing bulk oxygen vacancies in the ZnO structure to conduct oxygen ions or protons. Furthermore, we used experimental analysis, such as X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), ultraviolet–visible (UV–visible), X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy (EIS), to evaluate the change in structural properties and mechanism of ionic transport in ZnO nanorods with sodium doping. The presented work provides insight into a novel approach of developing the high ionic conductivity of electrolytes in a low-cost ZnO semiconductor material.
Syntheses and Crystal Structures of Three Chiral Oxazolidinones with Different Ring Conformations
Authors: Soru Ester , Cairney Grace , Storey John M. D. , Harrison William T. A.
Published: November 2022

The preparation of new, enantiomerically pure, α-amino acids from easily available starting materials is an ongoing challenge in synthetic organic chemistry. Here, we describe the syntheses and crystal structures of three chiral oxazolidinone derivatives prepared from L-alanine and pivalaldehyde to form a Schiff base intermediate and then reaction with the appropriate acid chloride to form the heterocycle. In each compound, the methyl and tert-butyl substituents lie to the same side of the molecule: these homochiral ‘cis’ structures were separated from their trans diastereomers by fractional crystallisation. The five-membered rings in these structures adopt various conformations including envelopes with either a C or O atom as the flap and twisted about a C–O bond. The extended structures of two of these compounds feature C(6) chains of molecules linked by C–H···O hydrogen bonds: one of these has a notably short H···O separation of 2.24 (3) Å.
A Review of the Giant Triton (Charonia tritonis), from Exploitation to Coral Reef Protector?
Authors: Motti Cherie A. , Cummins Scott F. , Hall Michael R.
Published: November 2022

Charonia tritonis (Charoniidae), one of the largest marine gastropods and an echinoderm specialist, preys on Crown-of-Thorns starfish (CoTS), a recurring pest that continues to be a leading cause of coral mortality on Indo-Pacific reefs. Widespread historical exploitation has impacted their numbers, with standing populations considered rare throughout their habitat. Their life-stage attributes, i.e., teleplanic larvae, planktotrophic phase spanning years permitting transoceanic dispersal, and recruitment to coral reefs through oceanic influx with intense larval mortality, have likely hindered their recovery. Decline in numbers is hypothesised to account partially for periodic CoTS outbreaks, yet predator-prey dynamics between these two species that might influence this are poorly understood. The C. tritonis excretory secretome elicits a proximity deterrence effect on CoTS, the nature of which is under investigation as a possible tool in CoTS biocontrol scenarios. However, specificity and zone of impact in situ are unknown, and whether the mere presence of C. tritonis and/or predation pressure has any regulatory influence over CoTS populations remains to be established. The fundamental taxonomy and distinctive characteristics, biology and ecology of C. tritonis is summarized, and knowledge gaps relevant to understanding their role within coral reefs identified. Information is provided regarding exploitation of C. tritonis across its habitat, and prospects for conservation interventions, including captive rearing and stock enhancement to repopulate local regions, are discussed. Its predator-prey ecology is also examined and potential to mitigate CoTS considered. Recommendations to direct future research into this predator and for its inclusion in a CoTS integrated pest management strategy to improve coral reef health are offered.
New Real-Time Impulse Noise Removal Method Applied to Chest X-ray Images
Authors: Rashid Nasr , Berriri Kamel , Albekairi Mohammed , Kaaniche Khaled , Ben Atitallah Ahmed , Khan Muhammad Attique , El-Hamrawy Osama I.
Published: November 2022

In this paper, we propose a new Modified Laplacian Vector Median Filter (MLVMF) for real-time denoising complex images corrupted by “salt and pepper” impulsive noise. The method consists of two rounds with three steps each: the first round starts with the identification of pixels that may be contaminated by noise using a Modified Laplacian Filter. Then, corrupted pixels pass a neighborhood-based validation test. Finally, the Vector Median Filter is used to replace noisy pixels. The MLVMF uses a 5 × 5 window to observe the intensity variations around each pixel of the image with a rotation step of π/8 while the classic Laplacian filters often use rotation steps of π/2 or π/4. We see better identification of noise-corrupted pixels thanks to this rotation step refinement. Despite this advantage, a high percentage of the impulsive noise may cause two or more corrupted pixels (with the same intensity) to collide, preventing the identification of noise-corrupted pixels. A second round is then necessary using a second set of filters, still based on the Laplacian operator, but allowing focusing only on the collision phenomenon. To validate our method, MLVMF is firstly tested on standard images, with a noise percentage varying from 3% to 30%. Obtained performances in terms of processing time, as well as image restoration quality through the PSNR (Peak Signal to Noise Ratio) and the NCD (Normalized Color Difference) metrics, are compared to the performances of VMF (Vector Median Filter), VMRHF (Vector Median-Rational Hybrid Filter), and MSMF (Modified Switching Median Filter). A second test is performed on several noisy chest x-ray images used in cardiovascular disease diagnosis as well as COVID-19 diagnosis. The proposed method shows a very good quality of restoration on this type of image, particularly when the percentage of noise is high. The MLVMF provides a high PSNR value of 5.5% and a low NCD value of 18.2%. Finally, an optimized Field-Programmable Gate Array (FPGA) design is proposed to implement the proposed method for real-time processing. The proposed hardware implementation allows an execution time equal to 9 ms per 256 × 256 color image.
Ultrasonography Assessment Based on Muscle Thickness and Echo Intensity in Post-Polio Patients
Authors: Mateos-Angulo Álvaro , Salazar-Agulló José Andrés , Roldán-Jiménez Cristina , Trinidad-Fernández Manuel , Cuesta-Vargas Antonio Ignacio
Published: November 2022

There is no specific designed diagnostic test for post-poliomyelitis syndrome. The most important symptoms of this syndrome are new loss of muscle strength and more fatigue. Previous studies have investigated muscle ultrasound parameters to distinguish neuromuscular disease patients from healthy controls. The aim of this study was to investigate if muscle thickness and echo intensity measured by ultrasound can discriminate post-poliomyelitis syndrome patients from healthy controls. A total of 29 post-polio patients and 27 healthy controls participated in this cross-sectional study. Anthropometric measures, muscle thickness, echo intensity using B-mode ultrasound in rectus femoris and biceps brachii muscles, and muscle strength test data were collected. Muscle thickness in rectus femoris was significantly lower in post-poliomyelitis patients than in healthy controls, but not in biceps brachii. Echo intensity in rectus femoris and biceps brachii was higher in post-poliomyelitis syndrome patients than in healthy controls. Correlations were found between muscle thickness and strength in the upper and lower limbs. The results of the present study showed that muscle thickness in rectus femoris and echo intensity in rectus femoris and biceps brachii can discriminate post-poliomyelitis syndrome patients from healthy controls. A better assessment is possible because it can observe differences and relevant parameters in this clinical population.
Application of Proteomics to the Study of the Therapeutics and Pathogenicity of Giardia duodenalis
Authors: Aziz Ahmad Fudail Eiyad , Roshidi Norhamizah , Othman Nurulhasanah , Mohd Hanafiah Khayriyyah , Arifin Norsyahida
Published: November 2022

Giardia duodenalis remains a neglected tropical disease. A key feature of the sustained transmission of Giardia is the ability to form environmentally resistant cysts. For the last 38 years, proteomics has been utilised to study various aspects of the parasite across different life cycle stages. Thirty-one articles have been published in PubMed from 2012 to 2022 related to the proteomics of G. duodenalis. Currently, mass spectrometry with LC-MS/MS and MALDI-TOF/TOF has been commonly utilised in proteomic analyses of Giardia, which enables researchers to determine potential candidates for diagnostic biomarkers as well as vaccine and drug targets, in addition to allowing them to investigate the virulence of giardiasis, the pathogenicity mechanisms of G. duodenalis, and the post-translational modifications of Giardia proteins throughout encystation. Over the last decade, valuable information from proteomics analyses of G. duodenalis has been discovered in terms of the pathogenesis and virulence of Giardia, which may provide guidance for the development of better means with which to prevent and reduce the impacts of giardiasis. Nonetheless, there is room for improving proteomics analyses of G. duodenalis, since genomic sequences for additional assemblages of Giardia have uncovered previously unknown proteins associated with the Giardia proteome. Therefore, this paper aims to review the applications of proteomics for the characterisation of G. duodenalis pathogenicity and the discovery of novel vaccine as well as drug targets, in addition to proposing some general directions for future Giardia proteomic research.
Bile Acids in Intrahepatic Cholestasis of Pregnancy
Authors: Majsterek Maciej , Wierzchowska-Opoka Magdalena , Makosz Inga , Kreczyńska Lena , Kimber-Trojnar Żaneta , Leszczyńska-Gorzelak Bożena
Published: November 2022

Intrahepatic cholestasis of pregnancy (ICP) is the most common, reversible, and closely related to pregnancy condition characterized by elevated levels of bile acids (BAs) in blood serum and an increased risk of adverse perinatal outcomes. Due to the complex interactions between the mother and the fetus in metabolism and transplacental BAs transport, ICP is classified as a fetal-maternal disease. The disease is usually mild in pregnant women, but it can be fatal to the fetus, leading to numerous complications, including intrauterine death. The pathophysiology of the disease is based on inflammatory mechanisms caused by elevated BA levels. Although ICP cannot be completely prevented, its early diagnosis and prompt management significantly reduce the risk of fetal complications, the most serious of which is unexpected intrauterine death. It is worth emphasizing that all diagnostics and management of ICP during pregnancy are based on BA levels. Therefore, it is important to standardize the criteria for diagnosis, as well as recommendations for management depending on the level of BAs, which undoubtedly determines the impact on the fetus. The purpose of this review is to present the potential and importance of BAs in the detection and rules of medical procedure in ICP.
Different Brain Phenotypes in Magnetic Resonance Imaging of Healthy Children after Prenatal Insults
Authors: Paules Cristina , Pérez Roche María Teresa , Marin Miguel Angel , Fayed Nicolás , García-Martí Gracián , Pisón Javier López , Oros Daniel , Pueyo Victoria
Published: November 2022

In this study, we used magnetic resonance imaging (MRI) to identify the different brain phenotypes within apparently healthy children and to evaluate whether these phenotypes had different prenatal characteristics. We included 65 healthy children (mean age, 10 years old) with normal neurological examinations and without structural abnormalities. We performed cluster analyses to identify the different brain phenotypes in the brain MRI images. We performed descriptive analyses, including demographic and perinatal characteristics, to assess the differences between the clusters. We identified two clusters: Cluster 1, or the “small brain phenotype” (n = 44), which was characterized by a global reduction in the brain volumes, with smaller total intracranial volumes (1044.53 ± 68.37 vs. 1200.87 ± 65.92 cm3 (p < 0.001)), total grey-matter volumes (644.65 ± 38.85 vs. 746.79 ± 39.37 cm3 (p < 0.001)), and total white-matter volumes (383.68 ± 40.17 vs. 443.55 ± 36.27 cm3 (p < 0.001)), compared with Cluster 2, or the “normal brain phenotype” (n = 21). Moreover, almost all the brain areas had decreased volumes, except for the ventricles, caudate nuclei, and pallidum areas. The risk of belonging to “the small phenotype” was 82% if the child was preterm, 76% if he/she was born small for his/her gestational age and up to 80% if the mother smoked during the pregnancy. However, preterm birth appears to be the only substantially significant risk factor associated with decreased brain volumes.
Best Practices for Sustainable Inter-Institutional Hybrid Learning at CHARM European University
Authors: Griffin Daniel , Gallagher Silvia , Vigano Vanessa , Mousa Dimitra , Van Vugt Sanne , Lodder Alex , Byrne Jake Rowan
Published: November 2022

CHARM European University offers an inter-institutional Master’s (MSc) in Global Challenges for Sustainability across five European university campuses using innovative, challenge-based, transdisciplinary, and student-centered pedagogies. However, delivering modules across multiple locations at the same time poses a major challenge. Multiple hybrid classrooms solve this challenge by offering spaces for students and staff to teach and learn locally and remotely. This study describes the first Participatory Action Research (PAR) cycle iteration of the design, implementation, testing, and delivery of hybrid classrooms within a European university alliance. Hybrid classroom collaboration was facilitated through videoconference software, and this research describes a collaborative space design for transdisciplinary teamwork within this environment. Perspectives from a technical expert on virtual learning environments, an educationalist who supports teaching staff, and a classroom-based teaching assistant are presented. Integrating educational principles and module learning outcomes, aligning physical build specifications, testing hardware and software, identifying pedagogical needs, facilitating professional development, and ensuring adequate time for testing is crucial for successful hybrid classroom delivery. This research contributes practical use cases and recommendations for educational and support staff delivering digital transformation through hybrid classrooms across inter-institutional co-operations.
Research on Path-Planning Algorithm Integrating Optimization A-Star Algorithm and Artificial Potential Field Method
Authors: Liu Lisang , Wang Bin , Xu Hui
Published: November 2022

A fusion pathfinding algorithm based on the optimized A-star algorithm, the artificial potential field method and the least squares method is proposed to meet the performance requirements of path smoothing, response speed and computation time for the path planning of home cleaning robots. The fusion algorithm improves the operation rules of the traditional A-star algorithm, enabling global path planning to be completed quickly. At the same time, the operating rules of the artificial potential field method are changed according to the path points found by the optimal A-star algorithm, thus greatly avoiding the dilemma of being trapped in local optima. Finally, the least squares method is applied to fit the complete path to obtain a smooth path trajectory. Experiments show that the fusion algorithm significantly improves pathfinding efficiency and produces smoother and more continuous paths. Through simulation comparison experiments, the optimized A-star algorithm reduced path-planning time by 60% compared to the traditional A-star algorithm and 65.2% compared to the bidirectional A-star algorithm path-planning time. The fusion algorithm reduced the path-planning time by 65.2% compared to the ant colony algorithm and 83.64% compared to the RRT algorithm path-planning time.
Research on Flexible Virtual Inertia Control Method Based on the Small Signal Model of DC Microgrid
Authors: Lu Shengyang , Yu Tongwei , Liu Huiwen , Zhang Wuyang , Sui Yuqiu , Yang Junyou , Zhang Li , Zhou Jiaxu , Wang Haixin
Published: November 2022

Renewable energy is usually connected to the DC micro-grid by a large number of power electronic devices, which have the advantages of a fast system response, but the disadvantage to reduce the inertia of the system, which makes the stability of the system worse. It is necessary to increase the inertia of DC micro-grid so that it can recover and stabilize well when it receives a disturbance. In this paper, a small-signal model of DC micro-grid with constant power load (CPL) is established, and a flexible virtual inertial (FVI) control method based on DC bus voltage real-time variation is proposed, by controlling the DC/DC converter of the energy storage system, the problem of system oscillation caused by introducing voltage differential link to the system is solved. Compared with the droop control method, the FVI control method can increase the inertia of DC micro-grid system, reduce the influence of small disturbances, and improve the stability of the system. Finally, the validity of the FVI control method based on small signal model is verified in dSPACE.
A General Model for Analyzing the Unsteady Pressure Performance of Composite Gas Reservoirs
Authors: Huang Yu , Ma Mingfeng , Wang Xin , Li Xiaoping
Published: November 2022

Based on the previous study of a single medium model, the dual medium model for the fractured composite reservoir and the triple medium model for a fracture–cavity composite reservoir was established, respectively. The similarities and differences in the corresponding pressure dynamic curves of each model were analyzed, and the general model of a composite gas reservoir composed of different inner and outer zones was obtained. The general model can be more easily used in actual production, and the accuracy and practicability of the model were verified by case analysis.
A Simple and Accurate Energy-Detector-Based Transient Waveform Detection for Smart Grids: Real-World Field Data Performance
Authors: Ekti Ali Riza , Wilson Aaron , Olatt Joseph , Holliman John , Yarkan Serhan , Fuhr Peter
Published: November 2022

Integration of distributed energy sources, advanced meshed operation, sensors, automation, and communication networks all contribute to autonomous operations and decision-making processes utilized in the grid. Therefore, smart grid systems require sophisticated supporting structures. Furthermore, rapid detection and identification of disturbances and transients are a necessary first step towards situationally aware smart grid systems. This way, high-level monitoring is achieved and the entire system kept operational. Even though smart grid systems are unavoidably sophisticated, low-complexity algorithms need to be developed for real-time sensing on the edge and online applications to alert stakeholders in the event of an anomaly. In this study, the simplest form of anomaly detection mechanism in the absence of any a priori knowledge, namely, the energy detector (also known as radiometer in the field of wireless communications and signal processing), is investigated as a triggering mechanism, which may include automated alerts and notifications for grid anomalies. In contrast to the mainstream literature, it does not rely on transform domain tools; therefore, utmost design and implementation simplicity are attained. Performance results of the proposed energy detector algorithm are validated by real power system data obtained from the DOE/EPRI National Database of power system events and the Grid Signature Library.
Influence of Ammonia Concentration on Solvay Soda Process Parameters and Associated Environmental and Energetic Effects
Authors: Cichosz Marcin , Kiełkowska Urszula , Łazarski Sławomir , Kiedzik Łukasz , Szkudlarek Marian , Skowron Kazimierz , Kowalska Beata , Żurawski Damian
Published: November 2022

Modifying the absorption process in soda production by the Solvay method requires performing many calculations and determining a new equilibrium process. An increase in ammonia concentration in the reaction solution causes kinetic changes in equilibrium. Changes to the Solvay soda production technology were determined using chemical and instrumental analysis methods. A modification of the process in the form of SAB was introduced. Information allowing the design of an additional absorber and its location in the network of technological devices was presented in the form of parameters using typical chemical engineering assumptions. Spectroscopic and electrochemical techniques were used for this purpose. The increase in total alkalinity due to the addition of ammonia to 135 mmol·20 cm−3 resulted in cooling savings of about 152.4 MJ·Mg−1 of soda. The ammonia desorption rate and process energy parameters were determined for the new system. The temperature requirements for the carbonation column were defined, and in particular, a technique was developed to minimize the cooling of the lower part of the reactor, which reduces the consumption of process energy. Emissions of CO2 were reduced from 11.70 to 7.85% and NH3 from 5.52 to 4.89% in exhaust gases from the carbonation column.
Quality Assessment of Biofuel Briquettes Obtained from Greenhouse Waste Using a Mobile Prototype Briquetting Machine with PTO Drive
Authors: Kabaş Önder , Ünal İlker , Sözer Salih , Selvi Kemal Cagatay , Ungureanu Nicoleta
Published: November 2022

Turkey has a large agricultural area and produces 55–60 million tons of biomass waste/year. This study aimed to obtain bio-briquettes from three types of dried greenhouse wastes and to determine their strength parameters. A prototype of a mobile briquetting machine driven by power take-off (PTO), with hydraulic pistons, and comprising a shredder and grinding or crushing unit with a briquetting pressure in the range of 0–190 MPa, was used. The physical parameters of the obtained briquettes were determined, including density, tumbler and shatter resistance, compression resistance, water intake capacity, and resistance to moisture-humidity. The results of physical and mechanical tests showed that the briquettes are of an extremely high quality. The maximum density, shatter and tumbler resistance were 1143.52 kg·m−3, 99.24% in pepper plant waste, and 98.52% in eggplant plant waste, respectively. Based on the analysis of compression tests obtained under 190 MPa (maximum compaction force of 450 kN), the maximum compression force, compression stress, and specific compression force were found in briquettes made from tomato plant wastes (3315 N, 69.43 N·mm−2, 40.09 N·mm−1, respectively). Overall, the results and variables affecting the strength parameters showed that greenhouse waste biomass is an excellent feedstock for the production of high quality bio-briquettes. The valorization of briquetted greenhouse waste with the proposed prototype contributes to the sustainability of the environment and to a reduction in energy costs for farmers.
Optimization of Cogeneration Power-Desalination Plants
Authors: Pietrasanta Ariana M. , Mussati Sergio F. , Aguirre Pio A. , Morosuk Tatiana , Mussati Miguel C.
Published: November 2022

The design of new dual-purpose thermal desalination plants is a combinatory problem because the optimal process configuration strongly depends on the desired targets of electricity and freshwater. This paper proposes a mathematical model for selecting the optimal structure, the operating conditions, and sizes of all system components of dual-purpose thermal desalination plants. Electricity is supposed to be generated by a combined-cycle heat and power plant (CCHPP) with the following candidate structures: (a) one or two gas turbines; (b) one or two additional burners in the heat recovery steam generator; (c) the presence or missing a medium-pressure steam turbine; (d) steam generation and reheating at low pressure. Freshwater is supposed to be obtained from two candidate thermal processes: and (e) a multi-effect distillation (MED) or a multi-stage flash (MSF) system. The number of effects in MED and stages in MSF are also discrete decisions. Different case studies are presented to show the applicability of the model for same cost data. The proposed model is a powerful tool in optimizing new plants (or plants under modernization) and/or improving existing plants for desired electricity generation and freshwater production. No articles addressing the optimization involving the discrete decisions mentioned above are found in the literature.
Effects of Different Heat Transfer Conditions on the Hydrogen Desorption Performance of a Metal Hydride Hydrogen Storage Tank
Authors: Chai Mu , Tan Jiahui , Gao Lingwei , Liu Zhenan , Chen Yong , He Kuanfang , Jiang Mian
Published: November 2022

To investigate the influence of thermal effects on the hydrogen desorption performance of the metal hydride hydrogen storage system, a two-dimensional numerical model was established based on a small metal hydride hydrogen storage tank, and its accuracy was verified by the temperature variations in the reaction zone of the hydrogen storage tank during hydrogen desorption. In addition, the influence of the heat transfer medium on the heat and mass transfer performance of the hydrogen desorption reaction was analyzed. An external heat transfer bath was added to simulate the thermal effect of the model during the hydrogen desorption reaction. The temperature and type of heat transfer medium in the heat transfer bath were modified, and the temperature and reaction fraction variations in each zone of the hydrogen storage model were analyzed. The results showed that under heat transfer water flow, the reaction rate in the center region of the hydrogen storage tank was gradually lower than that in the wall region. The higher the temperature of water flow, the shorter the total time required for the hydrogen desorption reaction and the shortening amplitude is reduced. The variations in the temperature and hydrogen storage capacity during hydrogen desorption were similar, with water and oil as the heat transfer medium, under the same flow rate and heat transfer temperature, however, the heat transfer time and hydrogen desorption time of water were about 10% and 5% shorter than that of oil, respectively. When the air was used as the heat transfer medium, the heat transfer rate of the air convection in the channel was lower than the heat transfer rate of the tank wall, reducing the temperature difference between the air and alloy on both sides of the wall, decreasing heat transfer efficiency, and significantly prolonging the time required for hydrogen desorption.
Sliding-Mode Current Control with Exponential Reaching Law for a Three-Phase Induction Machine Fed by a Direct Matrix Converter
Authors: Maidana Paola , Medina Christian , Rodas Jorge , Maqueda Edgar , Gregor Raúl , Wheeler Pat
Published: November 2022

The direct matrix converter (DMC) is considered to be an exciting power converter topology option for electric motor drives in industrial applications (elevators, hoists and cranes) and applications where size and weight are critical (e.g., the aerospace industry). Several control techniques have been developed to exploit the DMC’s benefits and achieve the desired performance with classic control techniques, such as field-oriented control and direct torque control, and more sophisticated ones, such as model predictive control and sliding mode control (SMC). SMC is attractive due to its robustness and fast response. However, this control strategy suffers from a phenomenon called chattering. Thus, a solution based on the exponential reaching law (ERL) is implemented to resolve this issue. The proposed method was validated using simulation and experimental results from tests on a three-phase induction machine.
Sustainable Management of Healthcare Settings’ Personnel Based on Intelligent Project-Oriented Approach for Post-War Development
Authors: Dotsenko Nataliia , Chumachenko Dmytro , Husieva Yuliia , Kosenko Nataliia , Chumachenko Igor
Published: November 2022

The paper considers the transformation of human resource management processes in the healthcare settings of Ukraine in the context of war and the COVID-19 pandemic. It is noted that the unstable and hostile environment of a healthcare setting during times of crisis leads to the need to change the personnel selection and team formation model to increase the adaptability and resilience of human resources involved in the provision of medical care. The key features of the human resource management process in a turbulent environment are the high migration activity of personnel, which leads to the need to reallocate resources, the need to operate under severe financial constraints, and the need to consider personnel as a non-renewable resource when it is impossible to attract additional resources. To ensure the reliability of the functioning of a medical institution, the transformation of human resource management processes should be based on strategic agility and human resource management, organizational resilience as a resource-based capability, corporate sustainability, and transformation of enterprises’ resources, which can be achieved by applying methodological support for resource management in a multi-project environment. Considering a network of medical institutions as a multi-project environment will allow using the methodology of project-oriented resource management, forming adaptive teams in a multi-project environment, to ensure flexible redistribution of resources both within a single institution and within a network of institutions. It is proposed to use formal transformations to manage a medical institution’s human resources. Applying the proposed approach for managing the human resources of a medical institution is considered. The formation of a project team that satisfies the minimum requirements with the maximum value of the team’s qualification score is considered. It is shown that the use of this methodological support made it possible to choose the composition of the project team with a minimum number and a maximum value of the characteristic.
Adaptive Virtual Synchronous Generator Based on Model Predictive Control with Improved Frequency Stability
Authors: Yang Xuhong , Li Hui , Jia Wei , Liu Zhongxin , Pan Yu , Qian Fengwei
Published: November 2022

With the massive integration of renewable energy into the grid, grid inertia and its stability continue to decrease. To improve inertia and facilitate grid restoration, a control strategy for radial basis function virtual synchronous generators based on model predictive control (MPC-VSG-RBF) is proposed in this paper. In this method, virtual synchronous generator (VSG) control strategy is introduced into the model predictive control (MPC), so that the reference value of the inner loop current can vary with the grid voltage and frequency. Using the radial basis function (RBF) neural network to adjust the VSG virtual inertia online can solve the large fluctuation of frequency and power caused by excessive load fluctuation. The simulation model was built based on MATLAB and compared and analyzed with the MPC control method. The simulation results show that: when the output power of the inverter changes, the model predictive control of the adaptive virtual synchronous generator can increase the inertia and stability of the power grid; by adjusting the moment of inertia, the system damping ratio is improved to effectively suppress the transient process overshoot and oscillation in medium power.
Decomposition of a Cooling Plant for Energy Efficiency Optimization Using OptTopo
Authors: Thiele Gregor , Johanni Theresa , Sommer David , Krüger Jörg
Published: November 2022

The operation of industrial supply technology is a broad field for optimization. Industrial cooling plants are often (a) composed of several components, (b) linked using network technology, (c) physically interconnected, and (d) complex regarding the effect of set-points and operating points in every entity. This leads to the possibility of overall optimization. An example containing a cooling tower, water circulations, and chillers entails a non-linear optimization problem with five dimensions. The decomposition of such a system allows the modeling of separate subsystems which can be structured according to the physical topology. An established method for energy performance indicators (EnPI) helps to formulate an optimization problem in a coherent way. The novel optimization algorithm OptTopo strives for efficient set-points by traversing a graph representation of the overall system. The advantages are (a) the ability to combine models of several types (e.g., neural networks and polynomials) and (b) an constant runtime independent from the number of operation points requested because new optimization needs just to be performed in case of plant model changes. An experimental implementation of the algorithm is validated using a simscape simulation. For a batch of five requests, OptTopo needs 61min while the solvers Cobyla, SDPEN, and COUENNE need 0.3 min, 1.4 min, and 3.1 min, respectively. OptTopo achieves an efficiency improvement similar to that of established solvers. This paper demonstrates the general feasibility of the concept and fortifies further improvements to reduce computing time.
Economic Feasibility of Tropical Forest Restoration Models Based on Non-Timber Forest Products in Brazil, Cambodia, Indonesia, and Peru
Authors: Gasparinetti Pedro , Brandão Diego Oliveira , Maningo Edward V. , Khan Azis , Cabanillas France , Farfan Jhon , Román-Dañobeytia Francisco , Bahri Adi D. , Ponlork Dul , Lentini Marco , Alexandre Nikola , Araújo Victor da Silva
Published: November 2022

Mobilizing funds is a major challenge to achieve scalable Forest Landscape Restoration projects. While pure ecological restoration may not be a feasible investment from the private perspective, combining native species with non-timber forest products (NTFP) species may be a solution for reaching large scale and financially sustainable forest restoration. This study addresses potential species combinations for 12 restoration models, three models being based in pure ecological restoration and nine models being based on agroforests with NTFP, their economic costs, and benefits in tropical forests in Brazil, Peru, Cambodia, and Indonesia. A total of 12 semi-structured interviews were conducted to capture the models’ productivity and prices. As for the prices that the producers did not know, specialized stores were consulted in the cities of the collection. The starting investment to restore 01 hectare (ha−1) of tropical forest ranged between US $104 and $7736, with an average of $1963 ha−1 and a standard deviation of $2196 ha−1, considering the 12 cases evaluated in 2018 and 2019. From nine restoration models that had economic purposes, financial indicators showed a median net present value (NPV) of $1548 ha−1, and a median internal rate of return of 22%, considering a discount rate of 10%. The NPV varied between $−685 ha−1 and $55,531 ha−1. Costs of pure ecological restoration were on average 42% lower than agroforestry systems, but did not produce direct income from NTFP, therefore yielding negative NPV. The study demonstrated the economic feasibility of seven of nine models that had economic objective, showing that there are promising business cases for private investment in tropical forest restoration.