bluuebunny/crossref_metadata_2025 huggingface dataset:
Physical Fitness Perception and Physical Education Enjoyment in 11- to 12-Year-Old Children
Authors: Borrego-Balsalobre Francisco José , Cavas-García Francisco , Díaz-Suárez Arturo , Martínez-Moreno Alfonso
Published: December 2022

Childhood motor competence plays a fundamental role in long-term adherence to physical activity. Enjoyment levels and self-perception of physical fitness increase motivation, commitment, and participation in physical activity. The objective of this study was to assess the body mass index (BMI), weight percentile, health status, physical fitness, and enjoyment levels of physical activity. A sample of 138 persons, of whom 67 were males and 71 females, with a mean BMI of 20.04 (2.35) answered the questionnaires Physical Activity Enjoyment Scale and the International Fitness Scale–self-report of physical fitness in young people. Tests were administered to measure functional fitness and anthropometric characteristics. Statistical analysis included calculation of Cronbach’s alpha, ANOVA and Pearson’s bivariate test correlations. The data indicate the reliability of the International Fitness Scale. No significant differences by gender were observed for the Physical Activity Enjoyment Scale. The BMI showed that significant positive correlations with 20 m sprint scores (p < 0.001, r = 0.367) and significant negative correlations with 6-minute lap scores (p < 0.001, r = −0.360) could be caused by an older physiological age. The overall physical fitness level of the children was medium-high, with most of the children enjoying physical education classes and slightly higher enjoyment values for males 40.88 (5.42) than females 40.31 (6.16).
Sputtering Process of ScxAl1−xN Thin Films for Ferroelectric Applications
Authors: Wall Jacob M. , Yan Feng
Published: December 2022

Several key sputtering parameters for the deposition of ScxAl1−xN such as target design, sputtering atmosphere, sputtering power, and substrate temperature are reviewed in detail. These parameters serve a crucial role in the ability to deposit satisfactory films, achieve the desired stoichiometry, and meet the required film thickness. Additionally, these qualities directly impact the degree of c-axis orientation, grain size, and surface roughness of the deposited films. It is systematically shown that the electric properties of ScxAl1−xN are dependent on the crystal quality of the film. Although it is not possible to conclusively say what the ideal target design, sputtering atmosphere, sputtering power, and substrate temperature should be for all sputtering processes, the goal of this paper is to analyze the impacts of the various sputtering parameters in detail and provide some overarching themes that arise to assist future researchers in the field in quickly tuning their sputtering processes to achieve optimum results.
Factors Affecting mHealth Technology Adoption in Developing Countries: The Case of Egypt
Authors: Said Ghada Refaat El
Published: December 2022

Mobile health apps are seeing rapid growth in the potential to improve access to healthcare services for disadvantaged communities, while enhancing the efficiency of the healthcare delivery value chain. Still, the adoption of mHealth apps is relatively low, especially in developing countries. In Egypt, an initiative for national-level healthcare coverage was launched in 2021, accompanied by a rise in mHealth start-ups. However, many of these projects did not progress beyond the pilot stage, with very little known about the antecedents of mHealth adoption for the Egyptian user. Semi-structured interviews were conducted with 22 Egyptians, aiming to uncover factors affecting the use of mHealth apps for Egyptian citizens. Some of these factors were introduced by previous studies, such as Perceived Service Quality, Perceived Risk, Perceived Ease of Use, and Trust. Others were not well established in the mHealth research strand, such as Perceived Reputation and Perceived Familiarity, while Governance, Personalized Experience, Explain-ability, Interaction, Language, and Cultural Issues, are novel factors introduced by the current research. The effect of these suggested independent variables on the willingness to adopt mHealth apps was validated using a survey administered to 150 Egyptians, confirming the significant positive effect of most of these factors on mHealth adoption in Egypt. This research contributes to methodology by introducing novel constructs in the mHealth research context, which might be specific to the target developing country. Practical implications were suggested for designers and healthcare service providers might increase the adoption of their apps in developing countries, such as Egypt.
State-of-the Art Research in Biomolecular Crystals
Authors: Moreno Abel
Published: December 2022

This special issue, State-of-the Art Investigations on Biomolecular Crystals, is focused on strategies to procure suitable crystals for high-resolution X-ray crystallographic investigations [...]
Amyloidosis Cutis Dyschromica in a 16-Year-Old Filipino Girl: A Case Report
Authors: Bautista Fendi EJ R. , Marte-Jimenez Marcia Marie S. , Jamora Maria Jasmin J.
Published: December 2022

Amyloidosis cutis dyschromica is a rare variant of primary cutaneous amyloidosis characterized by hyper- and hypopigmented macules. In this paper, we reported a case of a 16-year-old Filipino girl with hyper- and hypopigmented to depigmented macules on the upper and lower extremities, which started when she was 9 years of age.
Tension Pneumocephalus Caused by Ethmoidal Roof Fracture: Emergent Surgical Decompression
Authors: Kim Hak Sung , Kim Jae Ho , Kim Dae Kyun , Ha Sang Woo
Published: December 2022

Tension pneumocephalus is a neurosurgical emergency that occurs when air is trapped in the intracranial cavity, leading to brain compression and causing severe neurological symptoms such as decreases in motor function, sensory function, and consciousness. Most cases of pneumocephalus require conservative treatment; however, because of the possible fatal complications, rapid diagnosis and appropriate treatment are important. Here, we present the case of an 81-year-old male patient who had undergone head trauma three hours prior to being admitted to our emergency room (ER) because of mental cloudiness. The radiologic findings showed tension pneumocephalus caused by an ethmoidal roof fracture. Emergency reconstruction of the ethmoidal roof with craniotomy was performed to remove the intracranial air using normal saline irrigation. By sharing our experience with this case, we hope to provide an option for the treatment of such cases.
Extended Detrended Fluctuation Analysis of Coarse-Grained Time Series
Authors: Koronovskii Alexander A. , Blokhina Inna A. , Dmitrenko Alexander V. , Tuzhilkin Matvey A. , Moiseikina Tatyana V. , Elizarova Inna V. , Semyachkina-Glushkovskaya Oxana V. , Pavlov Alexey N.
Published: December 2022

A coarse-graining procedure, which involves averaging time series in non-overlapping windows followed by processing of the obtained multiple data sets, is the initial step in the multiscale entropy computation method. In this paper, we discuss how this procedure can be applied with other methods of time series analysis. Based on extended detrended fluctuation analysis (EDFA), we compare signal processing results for data sets with and without coarse-graining. Using the simulated data provided by the interacting nephrons model, we show how this procedure increases, up to 48%, the distinctions between local scaling exponents quantifying synchronous and asynchronous chaotic oscillations. Based on the experimental data of electrocorticograms (ECoG) of mice, an improvement in differences in local scaling exponents up to 41% and Student’s t-values up to 34% was revealed.
Bacteremia (Sepsis), Hepatorenal Syndrome, and Serum Creatinine Levels Rather than Types or Microbial Patterns Predicted the Short-Term Survival of Cirrhotic Patients Complicated with Spontaneous Bacterial Peritonitis
Authors: Huang Chien-Hao , Wang Sheng-Fu , Lee Chen-Hung , Wu Yen-Mu , Chang Ching , Chen Bo-Huan , Huang Yu-Tung , Ho Yu-Pin
Published: December 2022

(1) Background: Spontaneous bacterial peritonitis (SBP) is a major and severe complication in cirrhosis patients with ascites. Over the years, advance in antibiotic treatment has led to changes in microbial patterns in some regions, including the emergence of extended-spectrum beta-lactamases resistant (ESBL)-producing bacteria and an increase in Gram-positive bacteria (GPC). In addition, three SBP types (classic SBP, culture-negative neutrophilic ascites (CNNA), and monomicrobial non-neutrocytic bacterascites (MNB)), may also have different prognoses. Therefore, the study aimed to investigate the microbial pattern and the predictors of short-term outcomes in patients with SBP. (2) Methods: Patients discharged with a diagnosis of the first episode of SBP between January 2006 and July 2017 were enrolled. Patients’ clinical, demographic, hematological, and biochemical data were obtained at diagnosis, and the model for end-stage liver disease (MELD)-based scores were calculated accordingly. Patients were followed up until February 2018 or until death. (3) Results: A total of 327 patients were analyzed. The prevalence of classic SBP was nearly equivalent to CNNA. As for the microbial pattern, Gram-negative bacillus (GNB) remained more prevalent than GPC (75 vs. 25%), with E. coli being the most common bacterial species, followed by K. Pneumoniae and then Staphylococcus. The percentage of ESBL strain in culture-positive patients was 10.9%. By univariable and multivariable logistic regression survival analysis, there was no significant difference in predicting short-term mortality among the three SBP types, neither between GNB vs. GPC nor between ESBL- and non-ESBL-producing bacteria. Only bacteremia (sepsis), hepatorenal syndrome (HRS), and serum creatinine (Cr) were independent predictors of in-hospital and 3-month mortality, whereas HRS and Cr were independent predictors of 6-month mortality. (4) Conclusions: SBP types, Gram stain result, and ESBL strain did not affect survival. Only bacteremia (sepsis), HRS, and serum Cr independently predicted the short-term mortality in patients with SBP.
Cor Triatriatum Sinister Presenting as Cardioembolic Stroke in a Young Woman
Authors: Szabo Timea Magdolna , Heidenhoffer Erhard , Kirchmaier Ádám , Pelok Benedek , Frigy Attila
Published: December 2022

Cor triatriatum sinister is a rare congenital heart disease characterized by an additional fibromuscular membrane in the left atrium. Cardioembolic stroke is a rare complication of cor triatriatum sinister, especially among women. We hereby describe the case of an 18-year-old female patient, without a past medical history, presenting with cardioembolic stroke in the territory of the right posterior cerebral artery. During extensive diagnostic work-up, nonrestrictive cor triatriatum sinister and patent foramen ovale were diagnosed using transthoracic and transesophageal echocardiography. In clinical practice, it is important to identify congenital cardiac defects as potential substrates for cardioembolism in young patients. In our case, cor triatriatum sinister presenting as ischemic stroke was diagnosed, which is an uncommon finding, especially in young females. Determining the optimal management strategy for patients with cor triatriatum sinister complicated by cardioembolic stroke requires a multidisciplinary approach.
Systemic Diseases and Biological Dental Implant Complications: A Narrative Review
Authors: Sbricoli Luca , Bazzi Elissar , Stellini Edoardo , Bacci Christian
Published: December 2022

The relationship between periodontitis and such systemic disorders as diabetes, cardiovascular disease and obesity has been extensively investigated. There is less scientific evidence available, however, regarding the influence of systemic diseases on the risk of late failure of dental implant rehabilitation due to peri-implantitis. The aim of the present study was to review the literature on the role of several common systemic disorders (diabetes, obesity, cardiovascular disease, hypertension and osteoporosis) in the onset of peri-implantitis. A database search initially yielded 2787 studies of potential interest published up to 1 March 2022 (993 in PubMed; 908 in Web of Science; and 886 in Scopus). After removing 1190 duplicate articles and checking the titles, abstracts and full texts for relevance, 70 articles were selected for the present analysis. Only cohort, case-control studies and clinical case series were considered. Most of the literature concludes for no association between diabetes, cardiovascular disease, hypertension or osteoporosis and the risk of peri-implantitis. On the other hand, almost all the studies that investigated obesity as a risk factor for implant rehabilitation found a positive association between the two. Further longitudinal studies are needed to better understand the effects of systemic diseases on rehabilitation with dental implants.
Relaxation Exponents of OTOCs and Overlap with Local Hamiltonians
Authors: Balachandran Vinitha , Poletti Dario
Published: December 2022

OTOC has been used to characterize the information scrambling in quantum systems. Recent studies have shown that local conserved quantities play a crucial role in governing the relaxation dynamics of OTOC in non-integrable systems. In particular, the slow scrambling of OTOC is seen for observables that have an overlap with local conserved quantities. However, an observable may not overlap with the Hamiltonian but instead with the Hamiltonian elevated to an exponent larger than one. Here, we show that higher exponents correspond to faster relaxation, although still algebraic, and such exponents can increase indefinitely. Our analytical results are supported by numerical experiments.
Oracles in Decentralized Finance: Attack Costs, Profits and Mitigation Measures
Authors: Aspembitova Ayana T. , Bentley Michael A.
Published: December 2022

Decentralized finance (DeFi) is by far the most popular application of blockchain technology. Despite the wide acceptance of new financial instruments and services, there are still many unexplored areas in the field. We dedicate this research to the understanding of one of the most crucial limitations of decentralized finance—oracles. DeFi protocols, as well as other blockchain applications, function in a closed environment and regularly need to fetch real-world information (e.g., assets’ prices)—the tool used for this purpose is called an oracle. We review the existing oracle types in DeFi applications and focus our research on the least explored one: when another protocol, typically a decentralized exchange, serves as a price oracle. After explaining the mechanisms behind the decentralized exchanges, we introduce an algorithmic model that allows one to safely design a decentralized oracle and adjust crucial parameters. We believe that understanding and implementing the logic presented in the model can help to reduce the chances of price manipulations attacks, which are the most frequent incident types in DeFi.
Quantum Multi-Round Resonant Transition Algorithm
Authors: Yang Fan , Chen Xinyu , Zhao Dafa , Wei Shijie , Wen Jingwei , Wang Hefeng , Xin Tao , Long Guilu
Published: December 2022

Solving the eigenproblems of Hermitian matrices is a significant problem in many fields. The quantum resonant transition (QRT) algorithm has been proposed and demonstrated to solve this problem using quantum devices. To better realize the capabilities of the QRT with recent quantum devices, we improve this algorithm and develop a new procedure to reduce the time complexity. Compared with the original algorithm, it saves one qubit and reduces the complexity with error ϵ from O(1/ϵ2) to O(1/ϵ). Thanks to these optimizations, we can obtain the energy spectrum and ground state of the effective Hamiltonian of the water molecule more accurately and in only 20 percent of the time in a four-qubit processor compared to previous work. More generally, for non-Hermitian matrices, a singular-value decomposition has essential applications in more areas, such as recommendation systems and principal component analysis. The QRT has also been used to prepare singular vectors corresponding to the largest singular values, demonstrating its potential for applications in quantum machine learning.
The Impact of COVID-19 on Burns: A Brazilian Study
Authors: Moura Carolina , Bittencourt Marcela , Cazumbá Maria Luíza , Buda Alexandra , Bowder Alexis , Corlew Daniel Scott , Filho Fábio Mendes Botelho , Barboza Lucas , Pompermaier Laura
Published: December 2022

During the COVID-19 pandemic, some of the strategies chosen to contain the spread, such as social isolation and use of alcohol-based hand sanitizer, were suspected to increase the risk of domestic accidents, especially burns. The aim of this study was, therefore, to investigate possible differences in epidemiological trends among burned patients admitted to the main referral hospital of the State of Minas Gerais, Brazil, before and during the pandemic. Methods: All categories of new burns admitted at the Burn Unit of the João XXIII Hospital in Belo Horizonte, Minas Gerais. The study group consisted of burn patients admitted between 1 March and 31 December 2020, and the control group consisted of those admitted between 1 March and 31 December 2019. The population was analyzed descriptively, and differences between patients admitted before and during the pandemic were tested using t-test, Wilcoxon Mann–Whitney Rank Sum test, the Chi-Squared test or Fisher’s exact test, as appropriate. Results: During the study period, 914 patients were admitted at the burns unit, 535 before the pandemic (control group) and 379 during the pandemic (study group). During the pandemic, referral from other hospitals decreased, while time between injury and admission remained unchanged. TBSA% and LOS diminished, while the depth of burns, presence of inhalation injuries, and in-hospital mortality did not. In adults, the place and mechanism of injury changed during the pandemic, while in children they did not. Conclusion: Fewer patients with burns were referred for specialized burn care during the pandemic, although patients admitted for specialized burn care had smaller TBSA% and shorter LOS.
EdgeTrust: A Lightweight Data-Centric Trust Management Approach for IoT-Based Healthcare 4.0
Authors: Awan Kamran Ahmad , Ud Din Ikram , Almogren Ahmad , Khattak Hasan Ali , Rodrigues Joel J. P. C.
Published: December 2022

Internet of Things (IoT) is bringing a revolution in today’s world where devices in our surroundings become smart and perform daily-life activities and operations with more precision. The architecture of IoT is heterogeneous, providing autonomy to nodes so that they can communicate with other nodes and exchange information at any time. IoT and healthcare together provide notable facilities for patient monitoring. However, one of the most critical challenges is the identification of malicious and compromised nodes. In this article, we propose a machine learning-based trust management approach for edge nodes to identify nodes with malicious behavior. The proposed mechanism utilizes knowledge and experience components of trust, where knowledge is further based on several parameters. To prevent the successful execution of good and bad-mouthing attacks, the proposed approach utilizes edge clouds, i.e., local data centers, to collect recommendations to evaluate indirect and aggregated trust. The trustworthiness of nodes is ranked between a certain limit, and only those nodes that satisfy the threshold value can participate in the network. To validate the performance of the proposed approach, we have performed extensive simulations in comparison with existing approaches. The results show the effectiveness of the proposed approach against several potential attacks.
Performance Evaluation of C/C++, MicroPython, Rust and TinyGo Programming Languages on ESP32 Microcontroller
Authors: Plauska Ignas , Liutkevičius Agnius , Janavičiūtė Audronė
Published: December 2022

The rapid growth of the Internet of Things (IoT) and its applications requires high computational efficiency, low-cost, and low-power solutions for various IoT devices. These include a wide range of microcontrollers that are used to collect, process, and transmit IoT data. ESP32 is a microcontroller with built-in wireless connectivity, suitable for various IoT applications. The ESP32 chip is gaining more popularity, both in academia and in the developer community, supported by a number of software libraries and programming languages. While low- and middle-level languages, such as C/C++ and Rust, are believed to be the most efficient, TinyGo and MicroPython are more developer-friendly low-complexity languages, suitable for beginners and allowing more rapid coding. This paper evaluates the efficiency of the available ESP32 programming languages, namely C/C++, MicroPython, Rust, and TinyGo, by comparing their execution performance. Several popular data and signal processing algorithms were implemented in these languages, and their execution times were compared: Fast Fourier Transform (FFT), Cyclic Redundancy Check (CRC), Secure Hash Algorithm (SHA), Infinite Impulse Response (IIR), and Finite Impulse Response (FIR) filters. The results show that the C/C++ implementations were fastest in most cases, closely followed by TinyGo and Rust, while MicroPython programs were many times slower than implementations in other programming languages. Therefore, the C/C++, TinyGo, and Rust languages are more suitable when execution and response time are the key factors, while Python can be used for less strict system requirements, enabling a faster and less complicated development process.
Fabrication of 30 µm Sn Microbumps by Electroplating and Investigation of IMC Characteristics on Shear Strength
Authors: Na Chang-Yun , Jeon Byung-Min , Kim Jong-Wook , Jung Woon-Seok , Jeong Jae-Seong , Cho Sung-Min , Park Hwa-Sun
Published: December 2022

In this paper, we prepared a pure Sn microbump with a diameter of 30 µm using an electroplating method for a solder cap on a Cu post/Ni barrier and then determined its IMC characteristics and shear strength according to reflow recovery. In order to secure uniformity of the bump height, it was optimized through WID and WIW evaluation methods. Using an optimized plating system, bumps with a diameter of 30 µm, a height of 40 µm, and a space of 50 µm were formed on a 4-inch wafer. Shear strength was measured according to the number of reflows. IMC was evaluated through cross-sectional and plane analyses of bumps. Its correlation with shear strength according to the number of reflows was derived. The Sn plating system optimized each process condition according to the Sn concentration, current density, and temperature. The shape, surface condition, and height uniformity of the bump were quantified by a 3D profiler and FIB analysis. Height uniformity (WID) according to the concentration was confirmed to be approximately 2% when the Sn concentration was 60 g/L. WID according to the additive was confirmed to be 2% when the Sn concentration was 60 mL/L. WID according to the plating temperature was excellent in the shape of the bump at 30 °C, and a value of 2% was confirmed. The WIW for the Sn plating thickness on a 4-inch wafer was confirmed to have a value of ±3.88%. A shear test between the Cu and Sn junction was conducted to verify the shear strength of the manufactured bump. At this time, reflow was performed 1, 3, 5, 7, and 10 times for each sample. It was confirmed that as the number of flows increased, shear strength first increased. It then decreased sharply. It was confirmed that as the number of reflows increased, the thickness and cross-section area of the IMC first increased. They then gradually became saturated. The IMC between Cu and Sn was created in island form at the beginning of the reflow, resulting in increased roughness and shear strength. However, as the number of reflows increased, the roughness decreased since the IMC generated by the island was combined. The shear strength also decreased sharply.
Contrastive Learning via Local Activity
Authors: Zhu He , Chen Yang , Hu Guyue , Yu Shan
Published: December 2022

Contrastive learning (CL) helps deep networks discriminate between positive and negative pairs in learning. As a powerful unsupervised pretraining method, CL has greatly reduced the performance gap with supervised training. However, current CL approaches mainly rely on sophisticated augmentations, a large number of negative pairs and chained gradient calculations, which are complex to use. To address these issues, in this paper, we propose the local activity contrast (LAC) algorithm, which is an unsupervised method based on two forward passes and locally defined loss to learn meaningful representations. The learning target of each layer is to minimize the activation value difference between two forward passes, effectively overcoming the limitations of applying CL above mentioned. We demonstrated that LAC could be a very useful pretraining method using reconstruction as the pretext task. Moreover, through pretraining with LAC, the networks exhibited competitive performance in various downstream tasks compared with other unsupervised learning methods.
Zero Energy IoT Devices in Smart Cities Using RF Energy Harvesting
Authors: Zeb Hassan , Gohar Moneeb , Ali Moazam , Rahman Arif ur , Ahmad Waleed , Ghani Anwar , Choi Jin-Ghoo , Koh Seok-Joo
Published: December 2022

The invention of batteries made it possible to store electricity for many purposes. One of the purposes is to keep the operations of WSN running without any interruptions. The main drawback of sensor nodes is their limited energy sources. The researcher introduces the energy harvesting (EH) concept for IoT-based WSNs to overcome energy limitations and charge the IoT devices. Many energy harvesting techniques have been introduced, such as solar, thermal, and flow-based ones, but radio frequency (RF)-based EH techniques received great attention from researchers due to their easy availability (from TV, radio, and wireless frequencies). In this paper, we have conducted a real-world experiment on Powercast energy harvesting devices and examined the behavior of sensed data in different scenarios, such as indoor, distance (feet/meters), and directional antennas. In our experiments, we have observed that when a device is removed from the charger, the energy scavenging process degrades and reaches a dead state. To stop a device from entering a dead state, we introduce a mobile charger technique to charge the device and find the optimal place for chargers and sensor devices. During mobile charging, we have also observed that when the directional antennas change their angle, the energy scavenging process degrades. To tackle these problems, we introduced two algorithms for directional and omni-directional antennas that efficiently solve the problem. Furthermore, we have obtained results for these scenarios and show that this technique has a promising output.
A Review on Thermal Coupling of Metal Hydride Storage Tanks with Fuel Cells and Electrolyzers
Authors: Cetinkaya Sera Ayten , Disli Tacettin , Soyturk Gamze , Kizilkan Onder , Colpan C. Ozgur
Published: December 2022

Hydrogen is one of the energy carriers that has started to play a significant role in the clean energy transition. In the hydrogen ecosystem, storing hydrogen safely and with high volumetric density plays a key role. In this regard, metal hydride storage seems to be superior to compressed gas storage, which is the most common method used today. However, thermal management is a challenge that needs to be considered. Temperature changes occur during charging and discharging processes due to the reactions between metal, metal hydride, and hydrogen, which affect the inflow or outflow of hydrogen at the desired flow rate. There are different thermal management techniques to handle this challenge in the literature. When the metal hydride storage tanks are used in integrated systems together with a fuel cell and/or an electrolyzer, the thermal interactions between these components can be used for this purpose. This study gives a comprehensive review of the heat transfer during the charging and discharging of metal hydride tanks, the thermal management system techniques used for metal hydride tanks, and the studies on the thermal management of metal hydride tanks with material streams from the fuel cell and/or electrolyzers.
Distributed Nodal Voltage Regulation Method for Low-Voltage Distribution Networks by Sharing PV System Reactive Power
Authors: Wang Xiangdong , Wang Lei , Kang Wenfa , Li Tiecheng , Zhou Hao , Hu Xuekai , Sun Kai
Published: December 2022

With the intensive integration of photovoltaic (PV) sources into the low-voltage distribution networks (LVDN), the nodal voltage limit violations and fluctuation problem cause concerns on the safety operation of a power system. The intermittent, stochastic, and fluctuating characteristics of PV output power leads to the frequent and fast fluctuation of nodal voltages. To address the voltage limit violation and fluctuation problem, this paper proposes a distributed nodal voltage regulation method based on photovoltaic reactive power and on-load tap changer transformers (OLTC). Using the local Q/V (Volt/Var) feedback controller derived from the grid sensitivity matrix, the voltage magnitude information is adopted to adjust the output of PV systems. Moreover, in order to share the burden of voltage regulation among distributed PV systems, a weighted distributed reactive power sharing algorithm is designed to achieve the voltage regulation according to the rated reactive power. Theoretical analysis is provided to show the convergence of the proposed algorithm. Additionally, the coordination strategy for distributed PV systems and OLTC is provided to reduce the reactive power outputs of PV systems. Five simulation case studies are designed to show the effectiveness of the proposed voltage regulation strategy, where the voltage regulation and proportional reactive power sharing can be achieved simultaneously.
Research on Production Profiling Interpretation Technology Based on Microbial DNA Sequencing Diagnostics of Unconventional Reservoirs
Authors: Yang Haitong , Wang Lei , Qiang Xiaolong , Ren Zhengcheng , Wang Hongbo , Wang Yongbo , Wang Shuoliang
Published: December 2022

Production profiling technology is an important method for monitoring the dynamics of oil and gas reservoirs which can effectively improve the efficiency of oil recovery. Production profiling is a technique in which a test instrument is lowered from the tubing to the bottom of the well to measure flow, temperature, pressure, and density in a multi-layer section of a producing well. Normal production profiling process needs to stop production, operate complex, consume long time and high cost. Furthermore, the profile cannot be continuously monitored for a long time. To address these limitations, this paper proposes a production profiling interpretation method based on reservoir primitive microbial DNA sequencing. The microbial stratigraphic baseline with high-resolution features is obtained by sampling and DNA sequencing of produced fluid and cuttings from different wells. Specifically, the random forest algorithm is preferred and improved by comparing the accuracy, precision, recall, F1-score, and running time of three clustering methods: Naïve-Bayes classifier, random forest classifier, and back-propagation classifier. Constructing PSO-random forest model is based on stratigraphic records and produced fluid bacteria features. The computational accuracy and efficiency of this method allows it to describe the production profile for each formation. Moreover, this test process does not need to stop production with simple operation and does not pollute the formation. Meanwhile, by sampling fluid production at different stages, it can achieve the purpose of long-term effective dynamic monitoring of the reservoir.
Biomass and Coal Ash Sintering—Thermodynamic Equilibrium Modeling versus Pressure Drop Test and Mechanical Test
Authors: Król Karol , Moroń Wojciech , Nowak-Woźny Dorota
Published: December 2022

The problem of biomass combustion and co-combustion is a particularly important aspect of many district heating systems, where the use of biomass makes it possible to reduce CO2 emissions. The present article is a continuation of previous studies of the behavior of the mineral matter of selected fuels during the sintering processes. Three biomasses were studied: wheat straw, barley straw and rye straw, as well as two coals from Polish mines: bituminous coal and lignite. The study included ultimate and proximate analyses and oxide analysis. On the basis of the oxide analysis and using FactSage 8.0. software, the sintering process of ash from selected fuels was simulated. In particular, the content of the slag phase as well as the values of the specific heat cp and density were determined without considering the gas phase. The obtained results were compared with the results of measurements of fracture stress (mechanical method) and pressure drop (pressure drop test) determined during the sintering process of the ash samples. The study showed that there is a fairly pronounced correlation between the sintering temperatures determined by the mechanical and pressure drop test and the physical properties of the ashes, such as density and heat capacity, and chemical properties, i.e., the content of the slag phase. The completed research work indicates and confirms that nonstandard methods of studying ash sintering temperatures (mechanical and pressure drop test) are very promising because they directly reflect the behavior of coals and biofuels in combustion systems.
Coalbed Methane Reservoir Parameter Prediction and Sweet-Spot Comprehensive Evaluation Based on 3D Seismic Exploration: A Case Study in Western Guizhou Province, China
Authors: Wei Yuanlong , Zhao Lingyun , Liu Wei , Zhang Xiong , Guo Zhijun , Wu Zhangli , Yuan Shenghui
Published: December 2022

As a kind of clean energy, the exploration and development of coalbed methane (CBM) are of great importance and significance. In this paper, the CBM reservoir parameters of a working area in Western Guizhou Province, China, were predicted by using 3D seismic exploration technology, and the sweet-spot area was evaluated based on the prediction results. In terms of data interpretation, while the traditional technology is extended to the study of CBM, new technologies and methods suitable for CBM were also actively explored, especially in the quantitative prediction methods of parameters such as coal seam thickness, CBM content, coal body structure, in situ stress, etc., and a three-highs quantitative prediction technology of CBM sweet spots characterized by high precision, high resolution, and high coincidence was explored, which is based on logging evaluation and petrophysics. In addition, in the comprehensive evaluation of multiparameter sweet spots, the multiparameter weighted step-by-step evaluation method based on inversion was innovatively proposed, which made the prediction of CBM sweet spots more focused, effective, and practical, and the distribution law of sweet spots was more consistent with the geological law, providing enough basis for subsequent well location deployment. Based on this method, the C409 coal seam was selected as the sweet spot.
Study on Stability of Gas Pressure Regulator with a Built-In Silencer
Authors: Stadnik Dmitry , Sverbilov Victor , Ilyukhin Vladimir , Igolkin Alexander , Balyaba Maxim , Shakhmatov Evgeniy
Published: December 2022

Gas pressure regulators are widely used in gas transportation and distribution systems. They are designed for deep pressure reduction and maintainance with high accuracy over a wide flow range. Operation at a high pressure drop is accompanied by a high level of noise, for reduction of which, silencers are used. However, installation of a noise suppressor into the regulator design has a significant impact on its static and dynamic characteristics. This can lead to a decrease of accuracy, loss of stability and occurrence of self-oscillations of the valve. These, in turn, lead to increasing noise and vibration, wear of contact surfaces and premature failure of the regulator. The paper presents results of a study of dynamic characteristics of a modernized serial regulator with a built-in noise suppressor. A mathematical model was compiled and its study was carried out in the SimulationX software package. The joint influence on the system stability of the parameters of the muffler and the block of throttles, designed to adjust the static characteristic of the regulator, is considered. It is shown that the proper choice of throttle resistances can ensure the stability of the control system in a wide range of gas flow rates. The results can be used when designing regulators with built-in noise suppressors.
Utilization of a Commercial 3D Printer for the Construction of a Bio-Hybrid Device Based on Bioink and Adult Human Mesenchymal Cells
Authors: Morelli Giulio , Pescara Teresa , Greco Alessia , Montanucci Pia , Basta Giuseppe , Rossi Federico , Calafiore Riccardo , Gambelli Alberto Maria
Published: December 2022

The biofabrication of three-dimensional scaffolds using 3D printers and cell-containing bioinks is very promising. A wide range of materials and bioink compositions are being created and tested for cell viability and printability in order to satisfy the requirements of a bioink. This methodology has not still achieved technological maturity, and the actual costs mean that they are often inaccessible for researchers, consequently lowering the development and extending the required times. This research aims to apply this methodology on a laboratory scale by re-adapting a commercial 3D printer, consequently lowering the costs and energy impacts, and, at the same time, ensuring a level of accuracy extremely close to the currently adopted devices and, more in general, suitable for the scopes of the research. To accomplish this, we assembled a biomimetic scaffold made of human Umbilical Cord Matrix Stem Cells (hUCMS), cellulose, and alginate. Various molds were used to produce 3D scaffolds of different sizes. After bioprinting, cell viability was analyzed using ethidium bromide and fluorescein diacetate, and a histological stain was used to evaluate cell and bioink morphology. All of the examined bioinks had a uniform final 3D structure and were stable, easily printable, and procedure-adapted. Up until 21 days of culture, the bioinks remained unaltered and were simple to manipulate. After 7 and 21 days of cell culture, the hUCMS in the cellulose/alginate-based bioinks exhibited cell viabilities of 95% and 85%, respectively. The cells did not present with a fibroblast-like shape but appeared to be round-shaped and homogeneously distributed in the 3D structure. Biomimetic bioink, which is based on cellulose and alginate, is an appropriate hydrogel for 3D bioprinting. This preliminary work illustrated the potential use of these two biomaterials for the 3D bioprinting of mesenchymal stem cells.
Composting of Municipal Sewage Sludge and Lignocellulosic Waste: Nitrogen Transformations and Humic Substances Molecular Weight
Authors: Kulikowska Dorota , Bernat Katarzyna
Published: December 2022

As increasing soil organic matter is considered one of the main strategies for reducing desertification in Europe, the production and use of high-quality composts has gained importance during the last decade. It is undisputed that the quantity and quality of humic substances (HS) and their fractions, i.e. fulvic acids (FA) and humic acids (HA) in compost are considered important indicators of compost maturity and chemical stability. Other important aspects are concentrations of macro- and micronutrients and heavy metals (HMs) that are introduced to the soil with mature compost. In this light, this study assessed the detailed characteristic of compost from municipal sewage sludge. Moreover, kinetic of organic matter (OM), and nitrogen transformations, therein nitrogen loss, were analysed. OM degradation proceeded according to first-order kinetics. In the bioreactor, the rate constant of OM removal and the rate of OM removal were 0.134 d−1 and 12.6 mg/(g d.m.d), respectively. In the windrow, these constants were 5.2-fold and 16.7-fold lower, respectively. In mature compost, the concentration of HS equaled 240.3 mg C/g OM (1.65-fold higher than in the feedstock) and the concentrations of HA and FA were 120.7 mg C/g OM and 119.6 mg C/g OM, respectively. In FA predominated those with a molecular weight in the range of 10–30 kDa (47.2%), FA with a molecular weight >100 kDa accounted for only 14.4%. In HA, however, fraction with the highest molecular weight (>100 kDa) accounted for more than half (51.2%), while the share of HA with a molecular weight <10 kDa was only 6.8%. During composting, nitrogen loss was observed, which resulted from NH3 rather than N2O emission. In mature compost, organic nitrogen predominated (17.82 g/kg d.m.; ca. 92% of the overall nitrogen). The final concentrations of ammonia nitrogen and nitrate nitrogen were 0.23 and 1.12 g/kg d.m., respectively. The compost met the Polish requirements for the content of HMs (the HMs concentrations were as follows: Cd 1.85 mg/kg d.m., Pb 12.16 mg/kg d.m., Ni 11.05 mg/kg d.m., Cr 24.14 mg/kg d.m., Cu 104.24 mg/kg d.m., Zn 854 mg/kg d.m., Hg 0.12 g/kg d.m.).
VR, AR, and 3-D User Interfaces for Measurement and Control
Authors: Liccardo Annalisa , Bonavolontà Francesco
Published: December 2022

The topics of virtual, mixed, and extended reality have now become key areas in various fields of scientific and industrial applications, and the interest in them is made tangible by the numerous papers available in the scientific literature. In this regard, the Special Issue “VR, AR, and 3-D User Interfaces for Measurement and Control” received a fair number of varied contributions that analyzed different aspects of the implementation of virtual, mixed, and extended reality systems and approaches in the real world. They range from investigating the requirements of new potential technologies to the prediction verification of the effectiveness and benefits of their use, the analysis of the difficulties of interaction with graphical interfaces to the possibility of performing complex and risky tasks (such as surgical operations) using mixed reality viewers. All contributions were of a high standard and mainly highlight that measurement and control applications based on the new models of interaction with reality are by now increasingly ready to leave laboratory spaces and become objects and features of common life. The significant benefits of this technology will radically change the way we live and interact with information and the reality around us, and it will surely be worthy of further exploration, maybe even in a new Special Issue of Future Internet.
Extracting Statistical Properties of Solar and Photovoltaic Power Production for the Scope of Building a Sophisticated Forecasting Framework
Authors: Ndong Joseph , Soubdhan Ted
Published: December 2022

Building a sophisticated forecasting framework for solar and photovoltaic power production in geographic zones with severe meteorological conditions is very challenging. This difficulty is linked to the high variability of the global solar radiation on which the energy production depends. A suitable forecasting framework might take into account this high variability and could be able to adjust/re-adjust model parameters to reduce sensitivity to estimation errors. The framework should also be able to re-adapt the model parameters whenever the atmospheric conditions change drastically or suddenly—this changes according to microscopic variations. This work presents a new methodology to analyze carefully the meaningful features of global solar radiation variability and extract some relevant information about the probabilistic laws which governs its dynamic evolution. The work establishes a framework able to identify the macroscopic variations from the solar irradiance. The different categories of variability correspond to different levels of meteorological conditions and events and can occur in different time intervals. Thereafter, the tool will be able to extract the abrupt changes, corresponding to microscopic variations, inside each level of variability. The methodology is based on a combination of probability and possibility theory. An unsupervised clustering technique based on a Gaussian mixture model is proposed to identify, first, the categories of variability and, using a hidden Markov model, we study the temporal dependency of the process to identify the dynamic evolution of the solar irradiance as different temporal states. Finally, by means of some transformations of probabilities to possibilities, we identify the abrupt changes in the solar radiation. The study is performed in Guadeloupe, where we have a long record of global solar radiation data recorded at 1 Hertz.
Experimental Investigation of the Compaction-Crushing Characteristics of Graded Fractured Coal Gangue Based on Infill Mining
Authors: Pang Mingkun , Pan Hongyu , Yang Shihua , Zhu Shipeng , Zhang Tianjun
Published: December 2022

The compaction and re-crushing characteristics of crushed gangue are important factors which affect the quality and effectiveness of the filling of the quarry. To study the compaction and re-crushing characteristics of the gangue particles, continuous grading and intermittent grading of two different structures were designed to study the bulk gangue particle size distribution. By conducting a side-limited uniaxial compression test on the crushed gangue, the compaction deformation parameters and particle re-crushing parameters of the samples under different axial pressure and grading conditions were calculated, the interaction between compaction and re-crushing was determined, and a compaction-re-crushing model of the crushed gangue was established. The following conclusions were obtained, (1) the axial displacement increment and fractal dimension of the graded crushed gangue are closely related to the graded structure of the skeletal particles; (2) the compaction stage of the graded crushed gangue can be divided into a fast compaction stage, a slow compaction stage, and a stable compaction stage—the fast compaction stage is significantly elastic, the slow compaction stage is more plastic, and the stable stage behavior approaches that of the original rock body; (3) the degree of crushing of the graded crushed gangue increases with an increase in axial stress, and the re-crushing of the specimen mainly occurs in the slow compaction stage; (4) the compaction-crushing-fractal evolution of the graded crushed gangue in the lateral limit compression process is established as the line of questioning. The physical significance of the parameters in the equation is discussed in this paper. The study can provide theoretical support and engineering guidance for the precise filling of a quarry and the prevention of later collapse.
On the Variable Order Fractional Calculus Characterization for the Hidden Variable Fractal Interpolation Function
Authors: Raja Valarmathi , Gowrisankar Arulprakash
Published: December 2022

In this study, the variable order fractional calculus of the hidden variable fractal interpolation function is explored. It extends the constant order fractional calculus to the case of variable order. The Riemann–Liouville and the Weyl–Marchaud variable order fractional calculus are investigated for hidden variable fractal interpolation function. Moreover, the conditions for the variable fractional order μ on a specified range are also derived. It is observed that, under certain conditions, the Riemann–Liouville and the Weyl–Marchaud variable order fractional calculus of the hidden variable fractal interpolation function are again the hidden variable fractal interpolation functions interpolating the new data set.