bluuebunny/crossref_metadata_2025 huggingface dataset:
Dopamine, Serotonin, and Structure/Function Brain Defects as Biological Bases for Treatment Response in Delusional Disorder: A Systematic Review of Cases and Cohort Studies
Authors: Guàrdia Armand , González-Rodríguez Alexandre , Seeman Mary V. , Álvarez Aida , Estrada Francesc , Acebillo Sidharta , Labad Javier , Monreal José A.
Published: October 2021

Although blockade of dopamine receptors D2 and D3 appears to be the main mechanism of antipsychotic action, treatment response variability calls for an examination of other biological systems. Our aim is to systematically review reports of treatment response in delusional disorder (DD) in order to help determine its biological bases. Computerized searches of ClinicalTrials.gov, PubMed, and Scopus databases (from 1999 to September 2021) were systematically reviewed, in keeping with PRISMA directives. We used the search terms: (treat * OR therap * AND (delusional disorder)). We included all studies that explored the biological mechanisms of treatment response in DD, as diagnosed by ICD or DSM criteria. A total of 4344 records were initially retrieved, from which 14 papers were included: case reports, case series, and cohort studies. Findings point to (1) dopaminergic dysfunction (based on biochemical and genetic studies), (2) serotonergic dysfunction (based on partial agonism/antagonism of drugs), and (3) brain structure/function impairment, especially in the temporal and parietal lobes, as crucial factors in treatment response. Further studies with higher levels of evidence are needed to help clinicians determine treatment.
Characterization of a Novel Lutein Cleavage Dioxygenase, EhLCD, from Enterobacter hormaechei YT-3 for the Enzymatic Synthesis of 3-Hydroxy-β-ionone from Lutein
Authors: Long Zhangde , Duan Naixin , Xue Yun , Wang Min , Li Jigang , Su Zan , Liu Qibin , Mao Duobin , Wei Tao
Published: October 2021

3-Hydroxy-β-ionone, a flavor and fragrance compound with fruity violet-like characteristics, is widely applied in foodstuff and beverages, and is currently produced using synthetic chemistry. In this study, a novel lutein cleavage enzyme (EhLCD) was purified and characterized from Enterobacter hormaechei YT-3 to convert lutein to 3-hydroxy-β-ionone. Enzyme EhLCD was purified to homogeneity by ammonium sulfate precipitation, Q-Sepharose, phenyl-Sepharose, and Superdex 200 chromatography. The molecular mass of purified EhLCD, obtained by SDS-PAGE, was approximately 50 kDa. The enzyme exhibited the highest activity toward lutein, followed by zeaxanthin, β-cryptoxanthin, and β-carotene, suggesting that EhLCD exhibited higher catalytic efficiency for carotenoid substrates bearing 3-hydroxy-ionone rings. Isotope-labeling experiments showed that EhLCD incorporated oxygen from O2 into 3-hydroxy-β-ionone and followed a dioxygenase reaction mechanism for different carotenoid substrates. These results indicated that EhLCD is the first characterized bacterial lutein cleavage dioxygenase. Active EhLCD was also confirmed to be a Fe2+-dependent protein with 1 molar equivalent of non-haem Fe2+. The purified enzyme displayed optimal activity at 45 °C and pH 8.0. The optimum concentrations of the substrate, enzyme, and Tween 40 for 3-hydroxy-β-ionone production were 60 μM lutein/L, 1.5 U/mL, and 2% (w/v), respectively. Under optimum conditions, EhLCD produced 3-hydroxy-β-ionone (637.2 mg/L) in 60 min with a conversion of 87.0% (w/w), indicating that this enzyme is a potential candidate for the enzymatic synthesis of 3-hydroxy-β-ionone in biotechnological applications.
Green Synthesis of Pd Nanoparticles for Sustainable and Environmentally Benign Processes
Authors: Piermatti Oriana
Published: October 2021

Among transition metal nanoparticles, palladium nanoparticles (PdNPs) are recognized for their high catalytic activity in a wide range of organic transformations that are of academic and industrial importance. The increased interest in environmental issues has led to the development of various green approaches for the preparation of efficient, low-cost and environmentally sustainable Pd-nanocatalysts. Environmentally friendly solvents, non-toxic reducing reagents, biodegradable capping and stabilizing agents and energy-efficient synthetic methods are the main aspects that have been taken into account for the production of Pd nanoparticles in a green approach. This review provides an overview of the fundamental approaches used for the green synthesis of PdNPs and their catalytic application in sustainable processes as cross-coupling reactions and reductions with particular attention afforded to the recovery and reuse of the palladium nanocatalyst, from 2015 to the present.
Pulpbow: A Method to Study the Vasculogenic Potential of Mesenchymal Stem Cells from the Dental Pulp
Authors: Mantesso Andrea , Zhang Zhaocheng , Warner Kristy A. , Herzog Alexandra E. , Pulianmackal Ajai J. , Nör Jacques E.
Published: October 2021

Understanding how Mesenchymal Stem Cells (MSCs) form blood vessels is critical for creating mechanism-based approaches for the therapeutic use of these cells. In addition, understanding the determinants and factors involved in lineage hierarchy is fundamental to creating accurate and reliable techniques for the study of stem cells in tissue engineering and repair. Dental Pulp Stem Cells (DPSC) from permanent teeth and Stem cells from Human Exfoliated Deciduous teeth (SHED) are particularly interesting sources for tissue engineering as they are easily accessible and expandable. Previously, we have shown that DPSCs and SHEDs can differentiate into endothelial cells and form functional blood vessels through vasculogenesis. Here, we described how we created the “pulpbow” (pulp + rainbow), a multicolor tag experimental model that is stable, permanent, unique to each cell and passed through generations. We used the pulpbow to understand how dental pulp stem cells contributed to blood vessel formation in 3D models in in vitro and ex vivo live cell tracking, and in vivo transplantation assays. Simultaneous tracking of cells during sprout formation revealed that no single multicolor-tagged cell was more prone to vasculogenesis. During this process, there was intense cell motility with minimal proliferation in early time points. In later stages, when the availability of undifferentiated cells around the forming sprout decreased, there was local clonal proliferation mediated by proximity. These results unveiled that the vasculogenesis process mediated by dental pulp stem cells is dynamic and proximity to the sprouting area is critical for cell fate decisions.
The Emergence of Planetary Pediatrics
Authors: Oberg Charles
Published: October 2021

Pediatrics has witnessed an evolution from primary care, family-centered care, community pediatrics, social pediatrics and global pediatrics, which has shifted our attention beyond the clinic setting to an appreciation of children in their lived environment. We are witnessing the emergence of planetary pediatrics that further broadens the focus of children’s health to include the continued importance of clinical care, but also the impacts of climate change, environmental degradation, child migration, unrelenting war and conflict, social injustice, pandemics and violence against children. If we do not acknowledge the present and ever-increasing adverse planetary changes of what children are experiencing now and in the future, we will have failed to adequately protect them from impending catastrophes. The hope of pediatrics for the future is to improve the health and well-being of all children. This hope remains as relevant today as it was for our predecessors and serves as a beacon for the voyage through the remainder of the twenty-first century.
Properties of Al2O3 Thin Films Grown by PE-ALD at Low Temperature Using H2O and O2 Plasma Oxidants
Authors: Castillo-Saenz Jhonathan , Nedev Nicola , Valdez-Salas Benjamín , Curiel-Alvarez Mario , Mendivil-Palma María Isabel , Hernandez-Como Norberto , Martinez-Puente Marcelo , Mateos David , Perez-Landeros Oscar , Martinez-Guerra Eduardo
Published: October 2021

Al2O3 layers with thicknesses in the 25–120 nm range were deposited by plasma enhanced atomic layer deposition at 70 °C. Trimethylaluminum was used as organometallic precursor, O2 and H2O as oxidant agents and Ar as a purge gas. The deposition cycle consisted of 50 ms TMA pulse/10 s purge time/6 s of plasma oxidation at 200 W/10 s purge time. The optical constants and thicknesses of the grown layers were determined by spectroscopic ellipsometry, while the roughness was measured by atomic force microscopy, giving RMS values in the 0.29–0.32 nm range for films deposited under different conditions and having different thicknesses. High transmittance, ~90%, was measured by UV–Vis spectroscopy. X-ray photoelectron spectroscopy revealed that, with both types of oxidants, the obtained films are close to stoichiometric composition and, with high purity, no carbon was detected. Electrical characterization showed good insulating properties of both types of films, though the H2O oxidant leads to better I-V characteristics.
Nonlinear Dynamics and Performance Analysis of a Buck Converter with Hysteresis Control
Authors: Hoyos Velasco Carlos I. , Hoyos Velasco Fredy Edimer , Candelo-Becerra John E.
Published: October 2021

This paper presents the mathematical modeling and experimental implementation of a Buck converter with hysteresis control. The system is described using a state-space model. Theoretical and simulation studies show that the zero hysteresis control leads to an equilibrium point with the implication of an infinite commutation frequency, while the use of a constant hysteresis band induces a limit cycle with a finite switching frequency. There exists a tradeoff between voltage output ripple and transistor switching frequency. An experimental prototype for the Buck power converter is built, and theoretical results are verified experimentally. In general terms, the Buck converter with the hysteresis control shows a robust control with respect to load variations, with undesired high switching frequency taking place for a very narrow hysteresis band, which is solved by tuning the hysteresis band properly.
Impact of Thermal Treatment on the Surface of Na0.5Bi0.5TiO3-Based Ceramics
Authors: Bikse Liga , Dunce Marija , Birks Eriks , Kundzins Karlis , Freimanis Otto , Livins Maris , Gabrusenoks Jevgenijs , Sternberg Andris
Published: October 2021

Thermal etching is a widely accepted surface treatment method for studying microstructure in Na0.5Bi0.5TiO3-based compositions. Surprisingly, besides the flat pattern of grains (suitable for evaluating ceramics’ microstructure), images illustrating well-expressed relief and even microstructure consisting of partly bonded cubic-shaped grains are also found among the micrographs presented in various publications. The present paper shows that this different surface character in Eu-modified Na0.5Bi0.5TiO3 can be obtained through thermal treatment across a wide range of temperatures. At higher temperatures, remarkable growth of cubic-shaped grains on the surface is observed. This growth affects the grain size distribution on the surface more than it does within the bulk of a sample. Such micrographs cannot be used to characterise the microstructure of dense ceramics. Intensive growth of TiO2 inclusions at high thermal treatment temperatures is also observed, revealing substantial evaporation of Bi and Na from the surface of a ceramic sample, but not from its core part.
Study on Energy Evolution and Damage Constitutive Model of Siltstone
Authors: Zhou Ruihe , Guo Longhui , Hong Rongbao
Published: October 2021

In order to study the energy evolution characteristics and damage constitutive relationship of siltstone, the conventional triaxial compression tests of siltstone under different confining pressures are performed, and the evolution laws of input energy, elastic strain energy and dissipative energy of siltstone with axial strain and confining pressure are analyzed. According to the test results, the judgment criterion of the rock damage threshold is improved, and an improved three-shear energy yield criterion is proposed., The damage constitutive equation of siltstone is established based on the damage mechanics theory through the principle of minimum energy consumption and by considering the residual strength of rock, and lastly, the rationality of the model is verified by experimental data. The results reveal that (1) both the input energy and dissipative energy gradually increase with the increase of axial strain, and the elastic strain energy first increases and then decreases with the increase of axial strain, and reaches its maximum at the peak. (2) The input energy and dissipation energy increase exponentially with the increase of the confining pressure, and the elastic strain energy increases linearly with the increase of confining pressure. (3) According to the linear relationship between the sum of shear strain energy and hydrostatic pressure, an improved three-shear energy yield criterion is established. (4) The model curve can better describe the strain softening stage and the residual strength characteristics of siltstone. The relative standard deviation between the model results and the test results is only 4.35%, which verifies the rationality and feasibility of the statistical damage constitutive model that is established in this paper.
Keratoconus Diagnostic and Treatment Algorithms Based on Machine-Learning Methods
Authors: Malyugin Boris , Sakhnov Sergej , Izmailova Svetlana , Boiko Ernest , Pozdeyeva Nadezhda , Axenova Lyubov , Axenov Kirill , Titov Aleksej , Terentyeva Anna , Zakaraiia Tamriko , Myasnikova Viktoriya
Published: October 2021

The accurate diagnosis of keratoconus, especially in its early stages of development, allows one to utilise timely and proper treatment strategies for slowing the progression of the disease and provide visual rehabilitation. Various keratometry indices and classifications for quantifying the severity of keratoconus have been developed. Today, many of them involve the use of the latest methods of computer processing and data analysis. The main purpose of this work was to develop a machine-learning-based algorithm to precisely determine the stage of keratoconus, allowing optimal management of patients with this disease. A multicentre retrospective study was carried out to obtain a database of patients with keratoconus and to use machine-learning techniques such as principal component analysis and clustering. The created program allows for us to distinguish between a normal state; preclinical keratoconus; and stages 1, 2, 3 and 4 of the disease, with an accuracy in terms of the AUC of 0.95 to 1.00 based on keratotopographer readings, relative to the adapted Amsler–Krumeich algorithm. The predicted stage and additional diagnostic criteria were then used to create a standardised keratoconus management algorithm. We also developed a web-based interface for the algorithm, providing us the opportunity to use the software in a clinical environment.
Differences in Dynamics of Lung Computed Tomography Patterns between Survivors and Deceased Adult Patients with COVID-19
Authors: Akopyan Gevorg B. , Berdalin Alexander B. , Gubskiy Ilya L. , Lelyuk Vladimir G.
Published: October 2021

This study’s aim was to investigate CT (computed tomography) pattern dynamics differences within surviving and deceased adult patients with COVID-19, revealing new prognostic factors and reproducing already known data with our patients’ cohort: 635 hospitalized patients (55.3% of them were men, 44.7%—women), of which 87.3% had a positive result of RT-PCR (reverse transcription-polymerase chain reaction) at admission. The number of deaths was 53 people (69.8% of them were men and 30.2% were women). In total, more than 1500 CT examinations were performed on patients, using a GE Optima CT 660 computed tomography (General Electric Healthcare, Chicago, IL, USA). The study was performed at hospital admission, the frequency of repetitive scans further varied based on clinical need. The interpretation of the imaging data was carried out by 11 radiologists with filling in individual registration cards that take into account the scale of the lesion, the location, contours, and shape of the foci, the dominating types of changes, as well as the presence of additional findings and the dynamics of the process—a total of 45 parameters. Statistical analysis was performed using the software packages SPSS Statistics version 23.0 (IBM, Armonk, NY, USA) and R software version 3.3.2. For comparisons in pattern dynamics across hospitalization we used repeated measures general linear model with outcome and disease phase as factors. The crazy paving pattern, which is more common and has a greater contribution to the overall CT picture in different phases of the disease in deceased patients, has isolated prognostic significance and is probably a reflection of faster dynamics of the process with a long phase of progression of pulmonary parenchyma damage with an identical trend of changes in the scale of the lesion (as recovered) in this group of patients. Already known data on typical pulmonological CT manifestations of infection, frequency of occurrence, and the prognostic significance of the scale of the lesion were reproduced, new differences in the dynamics of the process between recovered and deceased adult patients were also found that may have prognostic significance and can be reflected in clinical practice.
Loss of DUSP4 Expression as a Prognostic Biomarker in Clear Cell Renal Cell Carcinoma
Authors: Bang Seongsik , Jee Seungyun , Son Hwangkyu , Wi Young Chan , Kim Hyunsung , Park Hosub , Myung Jaekyung , Shin Su-Jin , Paik Seung Sam
Published: October 2021

Dual-specificity protein phosphatase 4 (DUSP4) is a negative regulator of mitogen-activated protein kinases. The prognostic impact of DUSP4 expression in renal cell carcinoma is not well studied. Therefore, we evaluated the clinicopathological implications of DUSP4 expression in clear cell renal cell carcinoma by performing immunohistochemistry (IHC). The clinical outcome according to DUSP4 expression was evaluated through survival analyses, and the association between mRNA expression and prognosis was confirmed by online analysis (Kaplan–Meier plotter). Loss of DUSP4 expression was noted in most histological subtypes of renal cell carcinoma. Loss of DUSP4 expression in clear cell renal cell carcinoma was significantly correlated with old age (p = 0.033), high histologic grade (p < 0.001), tumor necrosis (p < 0.001), and high pT category (p < 0.001). In survival analysis, loss of DUSP4 expression was associated with poor clinical outcomes in cancer-specific survival and recurrence-free survival (p = 0.010 and p = 0.007, respectively). Upon TCGA data analysis, patients with low DUSP4 mRNA expression showed a shorter overall survival (p = 0.023). These results suggest that loss of DUSP4 expression can be used as a potential biomarker for predicting clinical outcomes in clear cell renal cell carcinoma patients.
Information Theory and Symbolic Analysis: Theory and Applications
Authors: Matilla-García Mariano , Marín Manuel Ruiz
Published: October 2021

Symbolic analysis has been developed and used successfully in very diverse fields [...]
Multi-Focus Image Fusion Method Based on Multi-Scale Decomposition of Information Complementary
Authors: Wan Hui , Tang Xianlun , Zhu Zhiqin , Li Weisheng
Published: October 2021

Multi-focus image fusion is an important method used to combine the focused parts from source multi-focus images into a single full-focus image. Currently, to address the problem of multi-focus image fusion, the key is on how to accurately detect the focus regions, especially when the source images captured by cameras produce anisotropic blur and unregistration. This paper proposes a new multi-focus image fusion method based on the multi-scale decomposition of complementary information. Firstly, this method uses two groups of large-scale and small-scale decomposition schemes that are structurally complementary, to perform two-scale double-layer singular value decomposition of the image separately and obtain low-frequency and high-frequency components. Then, the low-frequency components are fused by a rule that integrates image local energy with edge energy. The high-frequency components are fused by the parameter-adaptive pulse-coupled neural network model (PA-PCNN), and according to the feature information contained in each decomposition layer of the high-frequency components, different detailed features are selected as the external stimulus input of the PA-PCNN. Finally, according to the two-scale decomposition of the source image that is structure complementary, and the fusion of high and low frequency components, two initial decision maps with complementary information are obtained. By refining the initial decision graph, the final fusion decision map is obtained to complete the image fusion. In addition, the proposed method is compared with 10 state-of-the-art approaches to verify its effectiveness. The experimental results show that the proposed method can more accurately distinguish the focused and non-focused areas in the case of image pre-registration and unregistration, and the subjective and objective evaluation indicators are slightly better than those of the existing methods.
Study of Kinetic Freeze-Out Parameters as a Function of Rapidity in pp Collisions at CERN SPS Energies
Authors: Waqas Muhammad , Chen Huai-Min , Peng Guang-Xiong , Haj Ismail Abd Al Karim , Ajaz Muhammad , Wazir Zafar , Shehzadi Ramoona , Jamal Sabiha , AbdelKader Atef
Published: October 2021

We used the blast wave model with the Boltzmann–Gibbs statistics and analyzed the experimental data measured by the NA61/SHINE Collaboration in inelastic (INEL) proton–proton collisions at different rapidity slices at different center-of-mass energies. The particles used in this study were π+, π−, K+, K−, and p¯. We extracted the kinetic freeze-out temperature, transverse flow velocity, and kinetic freeze-out volume from the transverse momentum spectra of the particles. We observed that the kinetic freeze-out temperature is rapidity and energy dependent, while the transverse flow velocity does not depend on them. Furthermore, we observed that the kinetic freeze-out volume is energy dependent, but it remains constant with changing the rapidity. We also observed that all three parameters are mass dependent. In addition, with the increase of mass, the kinetic freeze-out temperature increases, and the transverse flow velocity, as well as kinetic freeze-out volume decrease.
Erratum: Martín-Montero et al. Bispectral Analysis of Heart Rate Variability to Characterize and Help Diagnose Pediatric Sleep Apnea. Entropy 2021, 23, 1016
Authors: Martín-Montero Adrián , Gutiérrez-Tobal Gonzalo C. , Gozal David , Barroso-García Verónica , Álvarez Daniel , Campo Félix del , Kheirandish-Gozal Leila , Hornero Roberto
Published: October 2021

The author wishes to make the following correction to this paper [...]
Analysis of the Pre-Service Teachers’ Academic Stress Based on Their Self-Concept and Personality
Authors: García-Martínez Inmaculada , Gavín-Chocano Óscar , León Samuel P. , Ubago-Jiménez José Luis
Published: October 2021

Self-concept is a key factor in any teaching–learning process in pre-service teachers. However, it could be negatively affected by academic stress, which is constituted by stressors, stress symptoms, and coping strategies. The aim of the study was to determine the relationship between academic stress and self-concept in this population. This was a descriptive, correlational, and cross-sectional study. The sample consisted of 1020 university students in education degrees. In relation to sex, it was found that 75.78% were women and 24.21% were men. The following instruments were used: Self-concept Form 5 (AF-5), the Big Five Inventory-44 (BFI-44), and the SISCO Inventory of Academic Stress. The results indicated that academic stress increases and self-concept decreases as studies progress; likewise, most of the students perceived high levels of stress. It was concluded that academic stress is inversely related to self-concept in pre-service teachers, a fact that should be taken into account in their initial training. Social-emotional factors and neuroticism have a decisive influence on the future teachers’ academic stress.
Speeding Up Velocity Consensus Control with Small World Communication Topology for Unmanned Aerial Vehicle Swarms
Authors: Ji Xiang , Zhang Wanpeng , Chen Shaofei , Luo Junren , Lu Lina , Yuan Weilin , Hu Zhenzhen , Chen Jing
Published: October 2021

This study addressed a problem of rapid velocity consensus within a swarm of unmanned aerial vehicles. Our analytical framework was based on tools using matrix theory and algebraic graph theory. We established connections between algebraic connectivity and the speed of converging on a velocity. The relationship between algebraic connectivity and communication cost was established. To deal with the trade-off among algebraic connectivity, convergence speed and communication cost, we propose a distributed small world network construction method. The small world network characteristics expedite the convergence speed toward consensus in the unmanned aerial vehicle swarm. Eventually, our method greatly sped up the consensus velocities in the unmanned aerial vehicle swarms at a lower communication cost than other methods required.
The Decreasing Hazard Rate Phenomenon: A Review of Different Models, with a Discussion of the Rationale behind Their Choice
Authors: Chiodo Elio , Mazzanti Giovanni
Published: October 2021

It is well known that, especially in the field of electronic components reliability studies and applications, the Exponential reliability model is by far the most adopted, although the data fostering it are few. This appears to be due partly to its simplicity (also in view of estimation, since it is characterized by a unique parameter), and partly because most components seem to be well represented, at least in their “useful life” time interval, by the Exponential model. This adoption is basically due to its peculiar “memory-less” property, i.e., the fact that such model possesses a constant hazard rate function, meaning that stochastic “accidents” cause the failure of the component, independently of its service time. This theoretical reason behind the choice of the Exponential model is largely prevailing over the classical statistical “goodness of fit” tests, since the high-reliability values attained by such devices does not allow the availability of an adequate number of lifetime values to be observed and analyzed in a statistical data analysis procedure. A second model also widely adopted is the Weibull model, especially if characterized by a shape parameter greater than unity, so implying an increasing hazard rate function. However, there are many cases—which can be also justified on a theoretical basis, as reviewed in this paper—in which a decreasing hazard rate function (at least for relatively large mission times) may be the best suited to describe the true model behind a given failure mechanism. The afore-mentioned theoretical basis of these apparently peculiar models is the main core of the present review article, whose aim also includes the illustration of the basic features of the main reliability models featuring an hazard rate function diminishing with time. The paper also discusses, resorting to graphical and numerical case-studies relevant to both field and simulated data, the consequences of mistaken model identification in terms of the hazard rate function behaviour, which may imply wrong maintenance actions.
Automated Workers’ Ergonomic Risk Assessment in Manual Material Handling Using sEMG Wearable Sensors and Machine Learning
Authors: Mudiyanselage Srimantha E. , Nguyen Phuong Hoang Dat , Rajabi Mohammad Sadra , Akhavian Reza
Published: October 2021

Manual material handling tasks have the potential to be highly unsafe from an ergonomic viewpoint. Safety inspections to monitor body postures can help mitigate ergonomic risks of material handling. However, the real effect of awkward muscle movements, strains, and excessive forces that may result in an injury may not be identified by external cues. This paper evaluates the ability of surface electromyogram (EMG)-based systems together with machine learning algorithms to automatically detect body movements that may harm muscles in material handling. The analysis utilized a lifting equation developed by the U.S. National Institute for Occupational Safety and Health (NIOSH). This equation determines a Recommended Weight Limit, which suggests the maximum acceptable weight that a healthy worker can lift and carry, as well as a Lifting Index value to assess the risk extent. Four different machine learning models, namely Decision Tree, Support Vector Machine, K-Nearest Neighbor, and Random Forest are developed to classify the risk assessments calculated based on the NIOSH lifting equation. The sensitivity of the models to various parameters is also evaluated to find the best performance using each algorithm. Results indicate that Decision Tree models have the potential to predict the risk level with close to 99.35% accuracy.
Two-Stage Modulation Study for DAB Converter
Authors: Guzmán Pablo , Vázquez Nimrod , Liserre Marco , Orosco Rodolfo , Pinto Castillo Sergio Enrique , Hernández Claudia
Published: October 2021

The dual active bridge (DAB) is a dc/dc converter frequently employed in multiple applications due to its advantages of isolation, power flexibility, and input and output voltage defined by design. Different multi-phase modulations have been reported to increase DAB efficiency and reduce components stress but, certainly, the control and implementation complexity increases with every displacement angle added because of the multiple variable measurements. This paper presents two-stage modulations based on the single phase-shift (SPS), which allows maintaining simplicity while improving the efficiency of the DAB converter depending on the design conditions. The paper also gives a direction for selecting the proper modulation to achieve the best efficiency for each situation. The different two-stage modulations are described, analyzed, and experimentally tested.
An Anomaly-Based Intrusion Detection System for Internet of Medical Things Networks
Authors: Zachos Georgios , Essop Ismael , Mantas Georgios , Porfyrakis Kyriakos , Ribeiro José C. , Rodriguez Jonathan
Published: October 2021

Over the past few years, the healthcare sector is being transformed due to the rise of the Internet of Things (IoT) and the introduction of the Internet of Medical Things (IoMT) technology, whose purpose is the improvement of the patient’s quality of life. Nevertheless, the heterogenous and resource-constrained characteristics of IoMT networks make them vulnerable to a wide range of threats. Thus, novel security mechanisms, such as accurate and efficient anomaly-based intrusion detection systems (AIDSs), considering the inherent limitations of the IoMT networks, need to be developed before IoMT networks reach their full potential in the market. Towards this direction, in this paper, we propose an efficient and effective anomaly-based intrusion detection system (AIDS) for IoMT networks. The proposed AIDS aims to leverage host-based and network-based techniques to reliably collect log files from the IoMT devices and the gateway, as well as traffic from the IoMT edge network, while taking into consideration the computational cost. The proposed AIDS is to rely on machine learning (ML) techniques, considering the computation overhead, in order to detect abnormalities in the collected data and thus identify malicious incidents in the IoMT network. A set of six popular ML algorithms was tested and evaluated for anomaly detection in the proposed AIDS, and the evaluation results showed which of them are the most suitable.
Comparative Study of Lattice Boltzmann Models for Complex Fractal Geometry
Authors: Zhang Dong , Wang Enzhi , Liu Xiaoli
Published: October 2021

A standard model, one of the lattice Boltzmann models for incompressible flow, is broadly applied in mesoscopic fluid with obvious compressible error. To eliminate the compressible effect and the limits in 2D problems, three different models (He-Luo model, Guo’s model, and Zhang’s model) have been proposed and tested by some benchmark questions. However, the numerical accuracy of models adopted in complex geometry and the effect of structural complexity are rarely studied. In this paper, a 2D dimensionless steady flow model is proposed and constructed by fractal geometry with different structural complexity. Poiseuille flow is first simulated to verify the code and shows good agreements with the theoretical solution, supporting further the comparative study on four models to investigate the effect of structural complexity and grid resolution, with reference results obtained by the finite element method (FEM). The work confirms the latter proposed models and effectively reduces compressible error in contrast to the standard model; however, the compressible effect still cannot be ignored in Zhang’s model. The results show that structural error has an approximately negative exponential relationship with grid resolution but an approximately linear relationship with structural complexity. The comparison also demonstrates that the He-Luo model and Guo’s model have a good performance in accuracy and stability, but the convergence rate is lower, while Zhang’s model has an advantage in the convergence rate but the computational stability is poor. The study is significant as it provides guidance and suggestions for adopting LBM to simulate incompressible flow in a complex structure.
Variable DC-Link Voltage Control of Dual Active Bridge Converter in a Standalone Wind Power Generation System for High-Efficiency Battery-Discharging Operation
Authors: Takayama Yuto , Yamada Hiroaki
Published: October 2021

In this study, we deal with a dual active bridge (DAB) converter-based battery charger in a standalone wind power generation system (WPGS) with a small-scale wind turbine. However, the power conversion efficiency under the low power output in the discharging mode is low. In this paper, we propose variable DC-link voltage control in a standalone WPGS with a DAB converter under a light load. The proposed control can compensate for the shortage of generated power and suppress the peak value of the transformer current. Simulation results demonstrate that the proposed control can decrease the peak value of the transformer current and improve the power conversion efficiency of the DAB converter. An experimental setup was constructed to confirm the basic operation of the variable DC-link voltage control. In addition, a reference DC-link voltage switchover control is proposed to enable a high-efficiency drive under all load ranges. From simulation results, the power loss can be reduced by the switchover control of the reference DC-link voltage.
Advanced Catalysis in Hydrogen Production from Formic Acid and Methanol
Authors: Bulushev Dmitri A.
Published: October 2021

The Special Issue of the Energies journal related to the hydrogen production from formic acid decomposition was published recently by MDPI. This Editorial note contains a short analysis of the papers published in this Special Issue and some historical information connected to this reaction.
Interlayer Microstructure Analysis of the Transition Zone in the Silicon/Perovskite Tandem Solar Cell
Authors: Kulesza-Matlak Grażyna , Drabczyk Kazimierz , Sypień Anna , Pająk Agnieszka , Major Łukasz , Lipiński Marek
Published: October 2021

The aim of the paper was to determine the morphology of the layers and the microstructure of the transition zone present in the proposed tandem solar structure. The bottom-silicon solar cell plays a double role: first as a highly porous non-reflecting material, and second as a scaffold for top-perovskite cell. In the presented solution, the use of a porous layer made of (e.g., TiO2) is excluded in favor of chemically etched wires on the silicon surface. The porous layer of silicon consists of nano- and microwires etched with metal assisted etching (MAE). The perovskite layer is introduced by a two-step chemical method into the spaces between the wires to fully fill them and intentionally form an additional capping layer at the same time. To examine the structure made in this way, advanced microscopic methods were used including scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM), also in high resolution.
Effects of the Multiple Injection Strategy on Combustion and Emission Characteristics of a Two-Stroke Marine Engine
Authors: Seol Ju-Hwan , Pham Van Chien , Lee Won-Ju
Published: October 2021

This paper presents research on the effects of the multiple injection strategies on the combustion and emission characteristics of a two-stroke heavy-duty marine engine at full load. The ANSYS FLUENT simulation software was used to conduct three-dimensional simulations of the combustion process and emission formations inside the engine cylinder in both single- and double-injection modes to analyze the in-cylinder pressure, temperature, and emission characteristics. The simulation results were then compared and showed good agreement with the measured values reported in the engine’s sea-trial technical reports. The simulation results showed reductions in the in-cylinder pressure and temperature peaks by 6.42% and 12.76%, while NO and soot emissions were reduced up to 24.16% and 68%, respectively, in the double-injection mode in comparison with the single-injection mode. However, the double-injection strategy increased the CO2 emission (7.58%) and ISFOC (23.55%) compared to the single-injection. These are negative effects of the double-injection strategy on the engine that the operators need to take into consideration. The results were in line with the literature reviews and would be good material for operators who want to reduce the engine exhaust gas emission in order to meet the stricter IMO emission regulations.
Influence of Selected Non-Ideal Aspects on Active and Reactive Power MRAS for Stator and Rotor Resistance Estimation
Authors: Lipcak Ondrej , Baum Filip , Bauer Jan
Published: October 2021

Mathematical models of induction motor (IM) used in direct field-oriented control (DFOC) strategies are characterized by parametrization resulting from the IM equivalent circuit and model-type selection. The parameter inaccuracy causes DFOC detuning, which deteriorates the drive performance. Therefore, many methods for parameter adaptation were developed in the literature. One class of algorithms, popular due to their simplicity, includes estimators based on the model reference adaptive system (MRAS). Their main disadvantage is the dependence on other machines’ parameters. However, although typically not considered in the respective literature, there are other aspects that impair the performance of the MRAS estimators. These include, but are not limited to, the nonlinear phenomenon of iron losses, the effect of necessary discretization of the algorithms and selection of the sampling time, and the influence of the supply inverter nonlinear behavior. Therefore, this paper aims to study the effect of the above-mentioned negative aspects on the performance of selected MRAS estimators: active and reactive power MRAS for the stator and rotor resistance estimation. Furthermore, improved reduced-order models and MRAS estimators that consider the iron loss phenomenon are also presented to examine the iron loss influence. Another merit of this paper is that it shows clearly and in one place how DFOC, with the included effect of iron losses and inverter nonlinearities, can be modeled using simulation tools. The modeling of the IM and DFOC takes place in MATLAB/Simulink environment.
Design of a Pendulum Prototype for Dynamic Testing of Material Removal Using Picks
Authors: Prendes-Gero María-Belén , González-Nicieza Celestino , Betegón-Biempica Covadonga , Álvarez-Fernández Martina-Inmaculada
Published: October 2021

The need for large and fast excavations, together with noise and vibration limitations, means that mechanical removal is increasingly used rather than blasting. In mechanical removal, the cutting tools hit the rock and penetrate it, and then move in the direction of cutting, dragging and detaching a portion of rock called chip. Most research on mechanical removal approaches it as a static process without taking into account the speed at which the cutting element impacts the rock. This work presents the design of a pendulum equipment capable of simulating the impact of a cutting element, specifically a pick, against a rock, reproducing the removal in a similar way to how it is carried out in real excavations. Cutting tests are carried out with concrete samples with a cement/sand ratio of 1:1 and 3:1, the volume of material that is removed is calculated using a 3D scanner and images of the tests are collected with a high-speed video camera to facilitate the interpretation of the results. The results confirm the direct relationship between impact energy, chip size and cutting depth, prove the formation of an affected zone that allows to reduce the cutting energy, and empirically obtain the optimum cutting energy with which the maximum performance in mechanical removal would be achieved.
Separation of 3He Isotope from Liquid Helium with the Use of Entropy Filter Composed of Carbon Nanotubes
Authors: Niechciał Jakub , Kempiński Wojciech , Stobiński Leszek , Trybuła Zbigniew , Banat Piotr , Chorowski Maciej , Poliński Jarosław , Chołast Katarzyna , Kociemba Andrzej
Published: October 2021

The 3He isotope finds applications in many areas of science and industry, the most important of which are cryogenics, where 3He allows for achieving millikelvins in dilution refrigerators, and public security with 3He detectors of radioactive materials at airports and important buildings. 3He is also used in medicine for lung tomography. One of the most extraordinary future applications is the use of 3He in fusion reactors for clean energy. 3He is currently very expensive, with prices reaching USD 2750 for 1 liter of gas in normal conditions; thus, more effort is put into finding economically viable methods to acquire this isotope. The article shows research results of acquiring the 3He isotope from liquid helium by a quantum separation method with the use of entropy filters based on new carbon nanomaterials: purified multiwall carbon nanotubes (MWCNTs) and purified multiwall carbon nanotubes decorated with ZrO2 nanoparticles. MWCNTs were bundled and applied in the form of pressed tablets with fixed sizes. The research was conducted at the low-temperature region, where helium exhibits its quantum properties by undergoing a phase transition to the superfluid phase at the lambda temperature: Tλ= 2.18 K. Entropy filters work below this temperature.
Optimal Modulation of Regenerative Braking in Through-The-Road Hybridized Vehicles
Authors: Rizzo Gianfranco , Tiano Francesco Antonio , Mariani Valerio , Marino Matteo
Published: October 2021

Regenerative braking can significantly improve the energy efficiency of hybrid and electric vehicles, and many studies have been carried out in order to improve and optimize the energy recovery of the braking energy. In the paper, the optimization of regenerative braking by means of braking force modulation is analysed, with specific application to the case of cars converted into Through-the-road (TTR) hybrid vehicles, and an optimal modulation strategy is also proposed. Car hybridization is an emerging topic since it may be a feasible, low-cost, intermediate step toward the green transition of the transport system with a potential positive impact in third-world countries. In this case, the presence of two in-wheel-motors installed on the rear axle and of the original mechanical braking system mounted on the vehicle can result in limited braking energy recovery in the absence of proper braking management strategies. A vehicle longitudinal model has been integrated with an algorithm of non-linear constrained optimization to maximize the energy recovery for various starting speed and stopping time, also considering the efficiency map and power limitations of the electric components. In the best conditions, the recovery can reach about 40% of the vehicle energy, selecting the best deceleration at each speed and proper modulation, and with a realistic estimate of the grip coefficient.
Risk-Adjusted Discount Rate and Its Components for Onshore Wind Farms at the Feasibility Stage
Authors: Saługa Piotr W. , Zamasz Krzysztof , Dacko-Pikiewicz Zdzisława , Szczepańska-Woszczyna Katarzyna , Malec Marcin
Published: October 2021

The concept of risk is well known in the energy sector. It is normally recognized when it comes to price and cost forecasting, annual production calculation, or evaluating project lifetime. Nevertheless, it should be pointed out that the quantitative evaluation of risk is usually difficult. The discount rate is the only parameter reflecting risk in the discounted cash flow analysis. Therefore, knowledge of the discount rate along with the major components affecting its level is of fundamental significance for making investment decisions, capital budgeting, and project management. By referring to the standard coal-fired power generation projects the authors of the paper tackle the analysis of the composition of discount rate for onshore wind farm technologies in the Polish conditions. The study was carried out on the basis of a typical (hypothetical) onshore wind farm project assessed at the feasibility stage. To enable comparisons and discussions, it was assumed that the best reference point for such purposes is the real risk-adjusted discount rate, RADR, after-tax, in all equity evaluations (the ‘bare bones’ assumption); that is because such a rate reflects the inherent characteristics of the project risk. The study methodology involves the a priori application of the discount rate level and subsequently—in an analytical way—calculation of its individual components. The starting point for the analysis of the RADR’s composition was the definition of risk, understood as the product of uncertainty and consequences. Then, the risk factors were adopted and level of uncertainty assessed. Subsequently, using the classical sensitivity analysis of IRR, the consequences (as slopes of sensitivity lines) were calculated. Consequently, risk portions in percentage forms were received. Eventually, relative risks and risk components within cost of equity were assessed. Apart from the characteristics of the discount rate at the feasibility stage, in the discussion section the study was supplemented with an analogous analysis of the project’s cost of equity at the operating stage.
Green Energy Technology
Authors: Chen Wei-Hsin , Ong Hwai Chyuan , Ho Shih-Hsin , Show Pau Loke
Published: October 2021

Our environment is facing several serious challenges from energy utilization, such as fossil fuel exhaustion, air pollution, deteriorated atmospheric greenhouse effect, global warming, climate change, etc [...]