bluuebunny/crossref_metadata_2025 huggingface dataset:
Combination of Hemoglobin-for-Age Z-Score and Plasma Hepcidin Identified as a Novel Predictor for Kawasaki Disease
Authors: Yang Ya-Ling , Kuo Ho-Chang , Chen Kuang-Den , Chu Chi-Hsiang , Kuo Kuang-Che , Guo Mindy , Chang Ling-Sai , Huang Ying-Hsien
Published: June 2022

Kawasaki disease (KD) is a febrile coronary vasculitis that affects younger children and includes complications such as coronary artery aneurysm. KD diagnoses are diagnosed based on clinical presentations, a process that still poses a challenge for front-line physicians. In the current study, we developed a novel predictor using the hemoglobin-for-age z-score (HbZ) and plasma hepcidin to differentiate Kawasaki disease (KD) from febrile children (FC). There were 104 FC and 115 KD subjects (89 typical KD; 26 incomplete KD) for this study, and data were collected on the biological parameters of hemoglobin and plasma hepcidin levels. A receiver operating characteristic curve (auROC), multiple logistics regression, and support vector machine analysis were all adopted to develop our prediction condition. We obtained both predictors, HbZ and plasma hepcidin, for distinguishing KD and FC. The auROC of the multivariate logistic regression of both parameters for FC and KD was 0.959 (95% confidence interval = 0.937–0.981), and the sensitivity and specificity were 85.2% and 95.9%, respectively. Furthermore, the auROC for FC and incomplete KD was 0.981, and the sensitivity and specificity were 92.3% and 95.2%, respectively. We further developed a model of support vector machine (SVM) classification with 83.3% sensitivity and 88.0% specificity in the training set, and the blind cohort performed well (78.4% sensitivity and 100% specificity). All data showed that sensitivity and specificity were 81.7% and 91.3%, respectively, by SVM. Overall, our findings demonstrate a novel predictor using a combination of HbZ and plasma hepcidin with a better discriminatory ability for differentiating from WBC and CRP between children with KD and other FC. Using this predictor can assist front-line physicians to recognize and then provide early treatment for KD.
Eating Disorders and Disordered Eating Behaviors in Cystic Fibrosis: A Neglected Issue
Authors: Petropoulou Anastasia , Bakounaki Georgia , Grammatikopoulou Maria G. , Bogdanos Dimitrios P. , Goulis Dimitrios G. , Vassilakou Tonia
Published: June 2022

As with the majority of chronic diseases having specific nutrition recommendations, in cystic fibrosis (CF), the emphasis placed on patients regarding their diet and ideal body weight status often increases the risk of developing disordered eating behaviors and by inference, eating disorders (EDs). Body weight appears to be an important concern for patients with CF, with many patients struggling to lose weight. Between sexes, women appear more preoccupied with dieting compared to men, but exhibit a better body image, mainly due to their preference for a lower weight. Several comorbidities appear to change these dynamics, and visibly apparent factors, including scars, ports, and tubes, and the need for supplementary oxygen supply, may also influence body image perception. Disordered eating is usually initiated during a bout of pulmonary infection, with the patient feeling unwell to eat. Regarding the prevalence of EDs, research appears conflicting on whether it is higher among individuals with a CF diagnosis or not. As for comorbidities, anxiety and depression consist of the most common psychiatric diagnoses in CF, also greatly prevalent in EDs. Despite the plethora of studies, non-specific CF tools, small samples, and lack of data regarding important outcomes, including lung health, indicate the need for more research.
Effect of Aqueous Extract of Phenolic Compounds Obtained from Red Wine in Experimental Model of Colitis in Mice
Authors: Mateus Vanessa , Estarreja João , Silva Inês , Gonçalves Fernando , Teixeira-Lemos Edite , Pinto Rui
Published: June 2022

Background: Inflammatory bowel disease (IBD) is a chronic relapsing inflammatory disorder represented by Crohn’s disease and ulcerative colitis. Currently, there is no cure and pharmacological treatment aims to induce and maintain remission on patients. Because the therapy reveals a relatively high toxicity, during a long-term utilization, it is essential to investigate new pharmacological approaches. Polyphenols, commonly present on red wine, have shown health-beneficial effects related to their antioxidant and anti-inflammatory effects through the inhibition of NF-kB activation, COX-2 and iNOS induction. In this sense, it would be interesting to study their effects in an IBD context. Therefore, this study aims to evaluate the effects of an aqueous extract of phenolic compounds in a 2,4,6-Trinitrobenzenesulfonic acid (TNBS)-induced model of colitis. Method: Experimental colitis was induced in mice through an intrarectal administration of TNBS and then the mice were treated with an aqueous extract of phenolic compounds intraperitoneally for four days. Results and Discussion: The extract demonstrated an anti-inflammatory effect, reducing TNF-α levels in the colon, and had a beneficial effect on the extraintestinal manifestations related to IBD, without any significant side effects. The extract of phenolic compounds demonstrated to be a valuable object of study for the management of IBD in the future.
Design of Photocatalytic Functional Coatings Based on the Immobilization of Metal Oxide Particles by the Combination of Electrospinning and Layer-by-Layer Deposition Techniques
Authors: Sandua Xabier , Rivero Pedro J. , Esparza Joseba , Fernández-Palacio José , Conde Ana , Rodríguez Rafael J.
Published: June 2022

This work reports the design and characterization of functional photocatalytic coatings based on the combination of two different deposition techniques. In a first step, a poly(acrylic acid) + β-Cyclodextrin (denoted as PAA+ β-CD) electrospun fiber mat was deposited by using the electrospinning technique followed by a thermal treatment in order to provide an enhancement in the resultant adhesion and mechanical resistance. In a second step, a layer-by-layer (LbL) assembly process was performed in order to immobilize the metal oxide particles onto the previously electrospun fiber mat. In this context, titanium dioxide (TiO2) was used as the main photocatalytic element, acting as the cationic element in the multilayer LbL structure. In addition, two different metal oxides, such as tungsten oxide (WO3) and iron oxide (Fe2O3), were added into PAA anionic polyelectrolyte solution with the objective of optimizing the photocatalytic efficiency of the coating. All of the coatings were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) images, showing an increase in the original fiber diameter and a decrease in roughness of the mats because of the LbL second step. The variation in the wettability properties from a superhydrophilic surface to a less wettable surface as a function of the incorporation of the metal oxides was also observed by means of water contact angle (WCA) measurements. With the aim of analyzing the photocatalytic efficiency of the samples, degradation of methyl blue (MB) azo-dye was studied, showing an almost complete discoloration of the dye in the irradiated area. This study reports a novel combination method of two deposition techniques in order to obtain a functional, homogeneous and efficient photocatalytic coating.
Model of Series-Parallel Photovoltaic Arrays Using Double-Diode Model and Parallel Computing
Authors: Bastidas-Rodríguez Juan David , Ramos-Paja Carlos Andrés , Serna-Garcés Sergio Ignacio
Published: June 2022

Several applications require to estimate the power production of photovoltaic (PV) systems under partial shading conditions. For example, dynamic reconfiguration of the array connections is needed to maximize the power production under partial shading conditions, which requires estimating the power generated by the PV array in several possible configurations. Therefore, a fast and accurate modeling technique is needed to perform those calculations in practical times and with low estimation errors. To address those kinds of problems, this paper proposes a modeling approach based on the double-diode model to provide high accuracy at low voltage and low irradiance conditions, which are important for partial-shading analysis. Moreover, the proposed modeling technique is designed to be implemented in parallel processing devices; thus, the calculation time is much shorter in comparison with classical serial solutions. The proposed model is tested in terms of accuracy and speed, obtaining satisfactory results. Finally, the applicability of the parallel model in reconfiguration applications is demonstrated using an application example.
Structural, Thermal and Functional Properties of a Hybrid Dicyanamide-Perovskite Solid Solution
Authors: García-Ben Javier , Salgado-Beceiro Jorge , Delgado-Ferreiro Ignacio , Dafonte-Rodríguez Pedro , López-Beceiro Jorge , Artiaga Ramón , Castro-García Socorro , Sánchez-Andújar Manuel , Bermúdez-García Juan Manuel , Señarís-Rodríguez María Antonia
Published: June 2022

In Solid-State Chemistry, a well-known route to obtain new compounds and modulate their properties is the formation of solid solutions, a strategy widely exploited in the case of classical inorganic perovskites but relatively unexplored among emergent hybrid organic–inorganic perovskites (HOIPs). In this work, to the best of our knowledge, we present the first dicyanamide-perovskite solid solution of [TPrA][Co0.5Ni0.5(dca)3] and study its thermal, dielectric and optical properties, comparing them with those of the parent undoped compounds [TPrA][Co(dca)3] and [TPrA][Ni(dca)3]. In addition, we show that the prepared doped compound can be used as a precursor that, by calcination, allows CNTs with embedded magnetic Ni:Co alloy nanoparticles to be obtained through a fast and much simpler synthetic route than other complex CVD or arc-discharge methods used to obtain this type of material.
X-ray Structure Analyses and Biological Evaluations of a New Cd(II) Complex with S-Triazine Based Ligand
Authors: Dahlous Kholood A. , Alotaibi Atallh A. M. , Dege Necmi , El-Faham Ayman , Soliman Saied M. , Refaat Heba M.
Published: June 2022

The crystal structure of a new penta-coordinated Cd(II) complex of the formula [Cd(BPMT)Br2] was presented. This Cd(II) complex was synthesized by mixing Cd(NO3)2·4H2O and 2,4-bis(3,5-dimethyl-1H-pyrazol-1-yl)-6-methoxy-1,3,5-triazine (BPMT) in the presence of KBr. It crystallized in the monoclinic crystal system and P21/n space group. The crystal parameters are a = 11.3680(8) Å, b = 11.1648(8) Å, c = 15.8593(11) Å, and β = 103.563(2)°, while the unit cell volume is 2190.6(12) Å3 and it comprised four molecules. The supramolecular structure of the [Cd(BPMT)Br2] complex is mainly controlled by the intermolecular Br∙∙∙H interactions. Hirshfeld calculations predicted the H∙∙∙H (38.1%), Br∙∙∙H (24.3%), C∙∙∙H (11.1%), and N∙∙∙H (9.5%) interactions are the most dominant. Biological evaluations for the antimicrobial and anticancer properties of the studied complex are presented. The Cd(II) complex has better anticancer and antibacterial activities than the free BPMT ligand. The anticancer activity against lung carcinoma (A-549) is higher for the former (18.64 ± 1.09 µg/mL) compared to the latter (372.79 ± 13.64 µg/mL). Additionally, the best antibacterial activity for the Cd(II) complex was found against B. subtilis.
Fabrication of Copper(II)-Coated Magnetic Core-Shell Nanoparticles Fe3O4@SiO2: An Effective and Recoverable Catalyst for Reduction/Degradation of Environmental Pollutants
Authors: Dadashi Jaber , Khaleghian Mohammad , Mirtamizdoust Babak , Hanifehpour Younes , Joo Sang Woo
Published: June 2022

In this work, we report the synthesis of a magnetically recoverable catalyst through immobilizing copper (II) over the Fe3O4@SiO2 nanoparticles (NPs) surface [Fe3O4@SiO2-L–Cu(II)] (L = pyridine-4-carbaldehyde thiosemicarbazide). Accordingly, synthesized catalysts were determined and characterized by energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), field emission scanning electron microscopy (FESEM), and thermogravimetric-differential thermal analysis (TG-DTA) procedures. The [Fe3O4@SiO2-L–Cu(II)] was used for the reduction of Cr(VI), 4-nitrophenol (4-NP) and organic dyes such as Congo Red (CR) and methylene blue (MB) in aqueous media. Catalytic performance studies showed that the [Fe3O4@SiO2–L–Cu(II)] has excellent activity toward reduction reactions under mild conditions. Remarkable attributes of this method are high efficiency, removal of a homogeneous catalyst, easy recovery from the reaction mixture, and uncomplicated route. The amount of activity in this catalytic system was almost constant after several stages of recovery and reuse. The results show that the catalyst was easily separated and retained 83% of its efficiency after five cycles without considerable loss of activity and stability.
An Up-to-Date Correlation of Epidemiological and Histopathological Characteristics of Basal Cell Carcinoma of the Skin in a County Hospital in Romania
Authors: Cocuz Iuliu Gabriel , Cocuz Maria Elena , Sabău Adrian-Horațiu , Niculescu Raluca , Tinca Andreea Cătălina , Vunvulea Vlad , Budin Corina Eugenia , Șincu Mihaela Cornelia , Popelea Maria Cătălina , Cotoi Ovidiu Simion
Published: June 2022

Background and Objectives: Basal carcinoma of the skin (BCC) is part of the nonmelanoma skin cancer (NMSC) family and is the most frequently occurring type of skin cancer in humans. A combination of clinical and histopathological approaches is necessary in order to establish the best treatment regime for patients who have been diagnosed with this type of cancer. The objective of the present study was to establish the statistical value of prediction for certain sociodemographic characteristics (age category and environment of origin) and histopathological parameters of the subjects that could be related to the incidence of diagnosis with certain histopathological subtypes of BCC. Materials and Methods: In order to verify the veracity of the established research hypotheses, we conducted a retrospective study based on the histopathological reports of 216 patients who were treated at the Pathology Department of Mureș Clinical County Hospital. Results: Cystic BCC is higher in patients who are older than 71 years of age, and the superficial multicentric and keratotic subtypes are more frequently diagnosed in urban areas. Patients who have been diagnosed with the superficial multicentric BCC subtype are not usually very old in contrast to the patients who tend to be diagnosed with the cystic BCC subtype. The nodular BCC subtype is positively associated with ulceration (p = 0.004); the superficial multicentric BCC subtype is positively associated with intra- and peritumoral inflammatory infiltrate (p = 0.022, p = 0.034) and negatively associated with ulceration (r = −0.218, p = 0.001). The infiltrative BCC subtype is positively associated with ulceration (p = 0.021), and the keratotic BCC subtype is positively associated with peritumoral inflammatory infiltrate (p = 0.02). Conclusions: Depending on each patient’s epidemiological and sociodemographic data, a pattern can be established regarding the appropriate clinical and treatment approaches for that patient, which can be supported based on the implications of the histopathological diagnostic. This can lead to an improvement in the patient’s quality of life and increased satisfaction with the provided medical services.
Undifferentiated Carcinoma with Osteoclast-Like Giant Cells of the Common Bile Duct: A Case Report of a Rare Entity at an Unusual Location
Authors: Chen Chuan-Han , Li Hsin-Ni
Published: June 2022

Undifferentiated carcinoma with osteoclast-like giant cells (UCOGC) is a rare variant of carcinoma with unique radiological and pathological features. This unusual carcinoma has been reported in a variety of organs and pancreas is the most frequently involved anatomical site. UCOGC of pancreas attains a relatively indolent clinical behavior and should be distinguished from ordinary pancreatobiliary adenocarcinoma. This paper presents the first case of UCOGC involving the entire segment of common bile duct (CBD) and common hepatic duct (CHD) without extending to the pancreatic tissue. Getting familiar with its clinical, radiological and pathological characters can help establish accurate diagnosis despite the occurrence of an unusual location.
A Generic Formula and Some Special Cases for the Kullback–Leibler Divergence between Central Multivariate Cauchy Distributions
Authors: Bouhlel Nizar , Rousseau David
Published: June 2022

This paper introduces a closed-form expression for the Kullback–Leibler divergence (KLD) between two central multivariate Cauchy distributions (MCDs) which have been recently used in different signal and image processing applications where non-Gaussian models are needed. In this overview, the MCDs are surveyed and some new results and properties are derived and discussed for the KLD. In addition, the KLD for MCDs is showed to be written as a function of Lauricella D-hypergeometric series FD(p). Finally, a comparison is made between the Monte Carlo sampling method to approximate the KLD and the numerical value of the closed-form expression of the latter. The approximation of the KLD by Monte Carlo sampling method are shown to converge to its theoretical value when the number of samples goes to the infinity.
Effects of Spatial Nonlocality versus Nonlocal Causality for Bound Electrons in External Fields
Authors: Christov Ivan P.
Published: June 2022

Using numerically exact solution of the time-dependent Schrödinger equation together with time-dependent quantum Monte Carlo (TDQMC) calculations, here we compare the effects of spatial nonlocality versus nonlocal causality for the ground state and for real-time evolution of two entangled electrons in parabolic potential in one spatial dimension. It was found that the spatial entanglement quantified by the linear quantum entropy is predicted with good accuracy using the spatial nonlocality, parameterized naturally within the TDQMC approach. At the same time, the nonlocal causality predicted by the exact solution leads to only small oscillations in the quantum trajectories which belong to the idler electron as the driven electron is subjected to a strong high frequency electric field, without interaction between the electrons.
Examining Supervised Machine Learning Methods for Integer Link Weight Prediction Using Node Metadata
Authors: Mori Larissa , O’Hara Kaleigh , Pujol Toyya A. , Ventresca Mario
Published: June 2022

With the goal of understanding if the information contained in node metadata can help in the task of link weight prediction, we investigate herein whether incorporating it as a similarity feature (referred to as metadata similarity) between end nodes of a link improves the prediction accuracy of common supervised machine learning methods. In contrast with previous works, instead of normalizing the link weights, we treat them as count variables representing the number of interactions between end nodes, as this is a natural representation for many datasets in the literature. In this preliminary study, we find no significant evidence that metadata similarity improved the prediction accuracy of the four empirical datasets studied. To further explore the role of node metadata in weight prediction, we synthesized weights to analyze the extreme case where the weights depend solely on the metadata of the end nodes, while encoding different relationships between them using logical operators in the generation process. Under these conditions, the random forest method performed significantly better than other methods in 99.07% of cases, though the prediction accuracy was significantly degraded for the methods analyzed in comparison to the experiments with the original weights.
Building Improvised Microbial Fuel Cells: A Model Integrated STEM Curriculum for Middle-School Learners in Singapore
Authors: Tan Timothy Ter Ming , Lee Yew-Jin
Published: June 2022

The benefits of STEM education for learning important knowledge, skills, and affect are widely accepted, though the former is currently absent in Singapore’s formal curriculum. This study therefore describes a model-integrated STEM curriculum at the middle-school level for developing scientific as well engineering literacy. Based on design-based inquiry (DBI), it incorporated inquiry science learning with an engineering design challenge for students to build improvised microbial fuel cells (MFC). Co-planned with science teachers from various disciplines, the curriculum was implemented as a 10-week enrichment program with two groups of Grade 8 students (N = 77) from one secondary school in Singapore. Through the use of vignettes, we show how learning about/of science and engineering occurred in the conceptual, epistemic, and social domains. In addition, students applied evidence-based reasoning, various epistemic skills, and a variety of problem-solving approaches as they iteratively improved their MFC set-ups, which often outperformed commercial kits. This proof-of-concept case study represents the first successful implementation of a STEM-integrated curriculum for middle-school students and can serve as a model for the development of similar programs elsewhere.
A Comprehensive Analysis of Privacy-Preserving Solutions Developed for Online Social Networks
Authors: Majeed Abdul , Khan Safiullah , Hwang Seong Oun
Published: June 2022

Owning to the massive growth in internet connectivity, smartphone technology, and digital tools, the use of various online social networks (OSNs) has significantly increased. On the one hand, the use of OSNs enables people to share their experiences and information. On the other hand, this ever-growing use of OSNs enables adversaries to launch various privacy attacks to compromise users’ accounts as well as to steal other sensitive information via statistical matching. In general, a privacy attack is carried out by the exercise of linking personal data available on the OSN site and social graphs (or statistics) published by the OSN service providers. The problem of securing user personal information for mitigating privacy attacks in OSNs environments is a challenging research problem. Recently, many privacy-preserving solutions have been proposed to secure users’ data available over OSNs from prying eyes. However, a systematic overview of the research dynamics of OSN privacy, and findings of the latest privacy-preserving approaches from a broader perspective, remain unexplored in the current literature. Furthermore, the significance of artificial intelligence (AI) techniques in the OSN privacy area has not been highlighted by previous research. To cover this gap, we present a comprehensive analysis of the state-of-the-art solutions that have been proposed to address privacy issues in OSNs. Specifically, we classify the existing privacy-preserving solutions into two main categories: privacy-preserving graph publishing (PPGP) and privacy preservation in application-specific scenarios of the OSNs. Then, we introduce a high-level taxonomy that encompasses common as well as AI-based privacy-preserving approaches that have proposed ways to combat the privacy issues in PPGP. In line with these works, we discuss many state-of-the-art privacy-preserving solutions that have been proposed for application-specific scenarios (e.g., information diffusion, community clustering, influence analysis, friend recommendation, etc.) of OSNs. In addition, we discuss the various latest de-anonymization methods (common and AI-based) that have been developed to infer either identity or sensitive information of OSN users from the published graph. Finally, some challenges of preserving the privacy of OSNs (i.e., social graph data) from malevolent adversaries are presented, and promising avenues for future research are suggested.
A New Compact Dual-Polarized MIMO Antenna Using Slot and Parasitic Element Decoupling for 5G and WLAN Applications
Authors: Paiva Samuel B. , Junior Adaildo G. D’Assunção , Neto Valdemir P. Silva , D’Assunção Adaildo Gomes
Published: June 2022

This paper presents a compact dual-polarized multiple-input multiple-output (MIMO) antenna for fifth generation (5G) and wireless local area network (WLAN) applications. At first, a compact two-element dual-polarized MIMO antenna designed to operate at 3.5 GHz was developed. After that, some modifications were performed in the initial configuration, and a compact two-element dual-polarized MIMO was designed to operate at 3.5 and 5.35 GHz. A simple decoupling technique using parasitic element and slot was used to enhance the isolation between the radiating elements and to achieve an isolation above 18 dB over the band ranging from 3.4 to 3.6 GHz for the first antenna, and to achieve isolations above 19.8 dB over the first band ranging from 3.4 to 3.6 GHz and above 16.75 dB over the second band ranging from 5.15 to 5.85 GHz for the second antenna. Simulations were performed in the Ansoft HFSS software for numerical characterization and the prototype was fabricated with FR-4 dielectric and measured, presenting a good agreement between simulated and measured results. Furthermore, the envelope correlation coefficient (ECC) and the diversity gain (DG) were analyzed and present good results.
Developing Countries in the Lead: A Bibliometric Approach to Green Finance
Authors: Desalegn Goshu , Tangl Anita
Published: June 2022

In recent years, green finance has become a popular method for dealing with environmental issues. However, it remains to be seen whether green financing is effective in addressing current global environmental issues. In this article, we, therefore, analyze the diffusion patterns of green finance publications in the Global South and Global North to identify which section of the globe is under-researched from this perspective. The study tried to highlight the overall trends of research publications on green finance, continent, most contributing authors, countries, and journals. The study used a bibliometric approach with the help of R studio software. The Scopus database was used for extracting the resources and 522 documents utilized in this bibliometric analysis. The result demonstrates that the diffusion of green finance is more common in the Global North than in the Global South. However, the number of scientific studies produced over time, the number of active authors, and affiliations of the Global South have contributed more than the Global North. More specifically, at the continental level, Asia and the Pacific are playing a lion’s share in providing scientific research publications on the green-finance-related issue. Meanwhile, the Arab states and Africa are the lowest contributing continent. China has the highest number of publications worldwide. However, this reality may be different if another approach (per capita contribution) is used to investigate the issue of green finance. Hence, we call for future studies to consider this fact in investigating the issue of green finance across the world. Furthermore, the study proposes further studies to be conducted on what are the factors that drive the Global South to lead. Finally, it is also better if the future studies take into account the status of each country in terms of green finance mobilization and capital contribution to share the specific experience of that country and lessons taken from that country.
Magnéli TiO2 as a High Durability Support for the Proton Exchange Membrane (PEM) Fuel Cell Catalysts
Authors: Thakare Jivan , Masud Jahangir
Published: June 2022

Proton exchange membrane fuel cells (PEMFCs) cathode catalysts’ robustness is one of the primary factors determining its long-term performance and durability. This work presented a new class of corrosion-resistant catalyst, Magnél TiO2 supported Pt (Pt/Ti9O17) composite, synthesized. The durability of a Pt/Ti9O17 cathode under the PEMFC operating protocol was evaluated and compared with the state-of-the-art Pt/C catalyst. Like Pt/C, Pt/Ti9O17 exhibited exclusively 4e− oxygen reduction reaction (ORR) in the acidic solution. The accelerated stress tests (AST) were performed using Pt/Ti9O17 and Pt/C catalysts in an O2-saturated 0.5 M H2SO4 solution using the potential-steps cycling experiments from 0.95 V to 0.6 V for 12,000 cycles. The results indicated that the electrochemical surface area (ECSA) of the Pt/Ti9O17 is significantly more stable than that of the state-of-the-art Pt/C, and the ECSA loss after 12,000 potential cycles is only 10 ± 2% for Pt/Ti9O17 composite versus 50 ± 5% for Pt/C. Furthermore, the current density and onset potential at the ORR polarization curve at Pt/C were significantly affected by the AST test. In contrast, the same remained almost constant at the modified electrode, Pt/Ti9O17. This demonstrated the excellent stability of Pt nanoparticles supported on Ti9O17.
Distributed Volt-Var Curve Optimization Using a Cellular Computational Network Representation of an Electric Power Distribution System
Authors: Dharmawardena Hasala , Kumar Venayagamoorthy Ganesh
Published: June 2022

Voltage control in modern electric power distribution systems has become challenging due to the increasing penetration of distributed energy resources (DER). The current state-of-the-art voltage control is based on static/pre-determined DER volt-var curves. Static volt-var curves do not provide sufficient flexibility to address the temporal and spatial aspects of the voltage control problem in a power system with a large number of DER. This paper presents a simple, scalable, and robust distributed optimization framework (DOF) for optimizing voltage control. The proposed framework allows for data-driven distributed voltage optimization in a power distribution system. This method enhances voltage control by optimizing volt-var curve parameters of inverters in a distributed manner based on a cellular computational network (CCN) representation of the power distribution system. The cellular optimization approach enables the system-wide optimization. The cells to be optimized may be prioritized and two methods namely, graph and impact-based methods, are studied. The impact-based method requires extra initial computational efforts but thereafter provides better computational throughput than the graph-based method. The DOF is illustrated on a modified standard distribution test case with several DERs. The results from the test case demonstrate that the DOF based volt-var optimization results in consistently better performance than the state-of-the-art volt-var control.
Thermophysical Properties of Liquids in Not Fully Stable States—From the First Steps to the Current Trends
Authors: Skripov Pavel
Published: June 2022

The present article marks the 95th anniversary of the birth of Vladimir P. Skripov, author of the classic study of superheated and supercooled liquids. It presents a discussion based on the early work carried out by Skripov and his research team in Ekaterinburg during the 1950s and 1960s. Due to their pioneering nature, these works laid the foundation for the study of metastable liquid states. For various reasons, although they remain relevant to this day, these groundbreaking works remain unknown to most non-Russian-speaking readers. As well as elucidating the behavior of the heat capacity of a solution in the liquid–liquid critical region, the presented research also concerns the characteristic features of light scattering and free-convective heat transfer in the liquid–vapor critical region of a one-component system, discussing two options for the position of the superheated liquid spinodal on the phase diagram of water, including the area of supercooled states and negative pressures. The issues involved in the discussion are united by the fluctuating nature of such phenomena. Indeed, the very possibility of their experimental study is due to a significant increase in the scale of fluctuations of the corresponding quantities when approaching the critical point or spinodal. The ongoing development of the approaches proposed in these papers for solving contemporary problems in the thermophysics of superheated liquids is discussed.
Experimental Study on Propagation Characteristics of Kerosene/Air RDE with Different Diameters
Authors: Xu Shida , Song Feilong , Zhou Jianping , Yang Xingkui , Cheng Peng
Published: June 2022

A series of experimental tests were carried out in order to study the propagation characteristics of a liquid kerosene rotating detonation engine (RDE) with different diameters. Distinguished characteristics of spatial and temporal instability were found in the large-scale RDE due to the uneven circumferential distribution of kerosene supply pressure. As for the two counter-waves detonation system, the 500 mm-diameter RDE maintains a higher detonation wave velocity due to its longer injection recovery time. However, the 220 mm-diameter RDE can obtain a larger equivalence ratio operation range, higher specific thrust, and higher specific impulse. In addition, compared with the deflagration combustion, the detonation combustion has higher chamber pressure and thrust under the same operational conditions.
Molecular Dynamics Simulation of the Oil–Water Interface Behavior of Modified Graphene Oxide and Its Effect on Interfacial Phenomena
Authors: Wang Jianzhong , Tian Suo , Liu Xiaoze , Wang Xiangtao , Huang Yue , Fu Yingchao , Xu Qingfa
Published: June 2022

Graphene oxide, as a new two-dimensional material, has a large specific surface area, high thermal stability, excellent mechanical stability and exhibits hydrophilic properties. By combining the carboxyl groups on the surface of graphene oxide with hydrophilic groups, surfactant-like polymers can be obtained. In this paper, based on the molecular dynamics method combined with the first nature principle, we first determine the magnitude of the binding energy of three different coupling agents—alkylamines, silane coupling agents, and haloalkanes—and analytically obtain the characteristics of the soft reaction. The high stability of alkylamines and graphene oxide modified by cetylamine, oil, and water models was also established. Then, three different chain lengths of simulated oil, modified graphene oxide–water solution, and oil-modified graphene oxide–water systems were established, and finally, the self-aggregation phenomenon and molecular morphology changes in modified graphene oxide at the oil–water interface were observed by an all-atom molecular dynamics model. The density profile, interfacial formation energy, diffusion coefficient and oil–water interfacial tension of modified graphene oxide molecules (NGOs) at three different temperatures of 300 K, 330 K, and 360 K were analyzed, as well as the relationship between the reduced interfacial tension and enhanced oil recovery (EOR).
Centralized and Distributed Optimization for Vehicle-to-Grid Applications in Frequency Regulation
Authors: El-Hendawi Mohamed , Wang Zhanle , Liu Xiaoyue
Published: June 2022

This paper proposes centralized and distributed optimization models for V2G applications to provide frequency regulation in power systems and the electricity market. Battery degradation and dynamic EV usages such as EV driving period, driving distance, and multiple charging/discharging locations are modeled. The centralized V2G problem is formulated into the linear programming (LP) model by introducing two sets of slack variables. However, the centralized model encounters limitations such as privacy concerns, high complexity, and central failure issues. To overcome these limitations, the distributed optimal V2G model is developed by decomposing the centralized model into subproblems using the augmented Lagrangian relaxation (ALR) method. The alternating direction method of multipliers (ADMM) is used to solve the distributed V2G model iteratively. The proposed models are evaluated using real data from the Independent Electricity System Operator (IESO) Ontario, Canada. Simulation results show that the proposed models can aggregate EVs for frequency regulation; meanwhile, the EV owners can obtain monetary rewards. The simulation also shows that including battery degradation and dynamic EV usage increases the model accuracy. By using the proposed approaches, the high cost and the low efficiency power generation units for frequency regulation can be compensated or partially replaced by EVs, which will reduce the generation cost and greenhouse gas emissions.
HOG-SVM-Based Image Feature Classification Method for Sound Recognition of Power Equipments
Authors: Bai Kang , Zhou Yong , Cui Zhibo , Bao Weiwei , Zhang Nan , Zhai Yongjie
Published: June 2022

In this paper, a method of power system equipment recognition based on image processing is proposed. Firstly, we carry out wavelet transform on the sound signal of power system equipment collected from the site, and obtain the wavelet coefficient–time diagram. Then, the similarity of wavelet coefficients–time images of different equipment and the same equipment in different periods is calculated, which is used as the basis of the feasibility of image recognition. Finally, we select the HOG features of the image, and classify the selected features using SVM classifier. The method proposed in this paper can accurately identify and classify power system equipment through sound signals, and is different from the traditional method of classifying sound signals directly. The advantages of image processing can be effectively utilized through image processing to avoid the limitations of sound signal processing.
Optimizing Low-Carbon Pathway of China’s Power Supply Structure Using Model Predictive Control
Authors: Ma Yue , Chu Xiaodong
Published: June 2022

With the increasing severity of climate change, the power industry, as one of the main sources of carbon emissions, is playing an extremely important role in the process of low-carbon energy transformation. The purpose of this paper is to try to find a general method to solve the optimal path for the low-carbon evolution of the power supply structure so as to meet the challenges faced by the low-carbon transformation of the power industry in the future. This paper first uses the capacity coefficient index (CCI) to represent the power generation ability of different technologies and proposes a forecasting method for the CCI of renewable energy generation. In this paper, a two-layer optimization model considering multiple constraints is established and solved using the MPC method. The results show that China’s installed capacity of renewable power could account for more than 50% in 2030, while the carbon emissions will decrease after reaching a peak in 2023. On the premise of ensuring sufficient reserve adjustment capacity of thermal power units, increasing the proportion of renewable energy generation is an important way to realize emission reduction in the power industry.
Variation Analysis Considering the Partial Parallel Connection in Aero-Engine Rotor Assembly
Authors: Ding Siyi , Zheng Xiaohu
Published: June 2022

The rotation precision of rotors determines the efficiency and quality of the overall aero-engine, as well as its long-term and reliable operation ability. As the terminal link of aero-engine manufacturing, the assembly is the last guarantee of precision control. Rotor assembly relates to the accurate expression of the connection form and design optimization of the assembly scheme. The existing variation model cannot adequately handle the partial parallel chain problem, ignoring the bayonet circular connector between the rotor parts, and it is still deficient in multistage gyration error control. In this paper, the partial parallel connection and multistage revolving characteristics of rotors were discussed, and a novel modeling and optimizing method for a partial parallel dimension chain was proposed. On the one hand, the variation expression of the connection features for the revolving components considering the partial parallel structure was researched. Contact point-based torsors were represented, and a system for locating points was regarded as an assembly to describe the partial parallel chain. On the other hand, the variation propagation modeling and control for the stacking of the multistage revolving components was researched. A revolution joint was introduced in the unified Jacobian–Torsor model, and a novel assembly technique for concentricity control was proposed. Therefore, a unified variation analysis and control method for rotor assembly has been developed. Experimental results show that through this method, the final concentricity variation is 0.0539 mm, far less than the 0.1595 mm of the traditional model, and is closer to the true value range of 0.030–0.040 mm. Moreover, the optimum installed angles can be calculated as 3.153 rad, 6.025 rad, and 2.590 rad, to obtain the highest concentricity of 0.040 mm, which has strong practical guiding significance.
Application of CFD Method to Investigate the Evolution of the Thermodynamic Parameters of a Hyper Compressor and Its Pipelines
Authors: Zhao Bin , Wei Huan , Zhai Yifeng , Feng Jianmei , Peng Xueyuan
Published: June 2022

Hyper compressors are key facilities for producing the low-density polyethylene with discharge pressure up to 350 MPa. Such high pressure brings great challenges to the design of the hyper compressor in many aspects. In this paper, a 3D transient computational fluid dynamics (CFD) model with inlet and outlet pipelines is built to investigate the thermodynamic performance of a hyper compressor. To realize the interaction between the thermodynamic processes and the pressure pulsation through valve dynamics, the pressures across the valve surfaces were monitored to the dynamic equation of the poppet valve. Then, structured grids were generated for the flow domain inside the valve, and the entire numerical model was solved by a commercial code: ANSYS Fluent. Consequently, the p-V diagram, the valve motion and pressure pulsation could be acquired simultaneously. The results of the numerical model showed that the exponents of the expansion and compression processes were 5.12 and 13.22, which were much larger than the common compressor. The maximal pressure pulsations were 13.25% and 22.07%, which occurred in the suction and discharge chambers, respectively. Severe flutter happened during the opening process of the suction valve due to the high incompressibility of the ethylene.
Novel PEV Charging Approaches for Extending Transformer Life
Authors: Smith Theron , Garcia Joseph , Washington Gregory
Published: June 2022

The study investigates how variable rate charging can affect PEV charging and identifies how this capability can be integrated into residential neighborhoods. The results show that creating PEV chargers that can deliver variable rates will enhance uncontrolled and controlled PEV charging. The integration is summarized into 4 phases. In phase 1, uncontrolled PEV chargers should be enabled to provide any rate to vehicles within 0 to 11.5 kW, which can reduce overloading by up to 28.34%. Phase 2 introduces smart chargers that use forecasted data to determine the optimal time intervals for PEVs to charge using a fixed rate of 4.8 kW, capable of reducing overloading by 42.69%. In Phase 3, a controlled smart charging strategy that can deliver any rate to a vehicle using SRVF’s approach is proposed, which will reduce overloading by up to 42.87%. Lastly, phase 4 recommends a smart charging control that can deliver any rate to a vehicle using RIVF’s approach, reducing overloading by up to 43.37%.
Calibration and Validation of Calcium Carbonate Precipitation Potential (CCPP) Model for Strontium Quantification in Cold Climate Aquatic Environments
Authors: Zanacic Enisa , McMartin Dena W.
Published: June 2022

The ability to robustly quantify the potential for strontium precipitation and scaling in both natural surface waters and water infrastructure systems is limited. In some regions, both surface and ground water supplies contain significant concentrations of naturally occurring radionuclides, such as strontium, that can accumulate in water, soils and sediments, media, and living tissues. Methods for quantifying and predicting the potential for these occurrences are not readily available nor have they been tested and calibrated to cold region aquatic environments. Through extensive literature review, it was determined that a modified calcium carbonate precipitation potential (CCPP) model offered a scientifically credible approach to filling that knowledge gap in both the science and engineering of strontium fate and transport in water. The results from previous field and laboratory experiments were compiled to not only elucidate the fate and transport of strontium in water systems, but also to calculate the logarithmic distribution coefficient, λ, for strontium under co-precipitation conditions. Lambda (λ) is both time- and water-quality sensitive and must be measured as water mixes from source to receiving environment to determine continuous loss of Sr from the water phase. The data were collected to develop the strontium precipitation potential model that can be used in surface water quality assessment. The tool was then applied to pre-existing, publicly available, and extensive datasets for several rivers in Saskatchewan, Canada, to validate the model and produce estimates for strontium precipitation potential in those rivers.
Forest Dependence of Rural Communities in the Republic of Moldova
Authors: Talpă Nicolae , Lozan Aurel , Hălălișan Aureliu Florin , Popa Bogdan
Published: June 2022

The high dependency on forest resources and the fact that forests play an important role in the lives of people in poorer rural areas are well known forest characteristics. This depicts a deep connection between people and nature. For the rural communities, forest ecosystems display another important role, namely in alleviating poverty through stable provisions of vital functions and livelihoods. The present study aims to identify what influences the current level of the local communities of the Republic of Moldova’s dependence on forests, who still face poverty-related challenges, and how ecosystem services provided by forests are perceived by the rural population. After six years since the last forest dependency research, this time the level of dependence is investigated using the same methodology, but through improved socio-economic conditions. Although the consumption of non-timber forest products decreased, the pressure on forest resources remained at the same level due to the high dependence of communities on firewood. The highest dependency was found in low-income households, manifested by their necessity to spend an average share of 18.8% from their total income on firewood due to their restricted access to forest resources. Since most Moldovans rely more heavily on subsistence-oriented forest products such as fuelwood, forest management sustainability efforts might not be achieved as long as the need for wood products exceeds the supply, and neither will the living conditions of the poor be improved. Solutions should be sought based on cross-sectoral and long-term approaches by involving all stakeholders, and not neglecting local communities.