bluuebunny/crossref_metadata_2025 huggingface dataset:
Dissipative Dynamics of Non-Interacting Fermion Systems and Conductivity
Authors: Yamaga Kazuki
Published: November 2020

In this paper, Non-Equilibrium Steady State that is induced by electric field and the conductivity of non-interacting fermion systems under the dissipative dynamics is discussed. The dissipation is taken into account within a framework of the quantum dynamical semigroup introduced by Davies (1977). We obtain a formula of the conductivity for the stationary state, which is applicable to arbitrary potentials. Our formula gives a justification of an adiabatic factor that is often introduced in practical calculation while using the Kubo formula. In addition, the conductivity of crystals (i.e., periodic potentials) is also discussed.
Modeling the Impact of Unreported Cases of the COVID-19 in the North African Countries
Authors: Djilali Salih , Benahmadi Lahbib , Tridane Abdessamad , Niri Khadija
Published: November 2020

In this paper, we study a mathematical model investigating the impact of unreported cases of the COVID-19 in three North African countries: Algeria, Egypt, and Morocco. To understand how the population respects the restriction of population mobility implemented in each country, we use Google and Apple’s mobility reports. These mobility reports help to quantify the effect of the population movement restrictions on the evolution of the active infection cases. We also approximate the number of the population infected unreported, the proportion of those that need hospitalization, and estimate the end of the epidemic wave. Moreover, we use our model to estimate the second wave of the COVID-19 Algeria and Morocco and to project the end of the second wave. Finally, we suggest some additional measures that can be considered to reduce the burden of the COVID-19 and would lead to a second wave of the spread of the virus in these countries.
Febuxostat, a Xanthine Oxidase Inhibitor, Decreased Macrophage Matrix Metalloproteinase Expression in Hypoxia
Authors: Wei Shuoyu , Isagawa Takayuki , Eguchi Masamichi , Sato Daisuke , Tsukano Hiroto , Miyata Keishi , Oike Yuichi , Takeda Norihiko , Ikeda Satoshi , Kawano Hiroaki , Maemura Koji
Published: November 2020

Macrophages in the atheroma region produce matrix metalloproteinases (MMPs) and decrease plaque stability. Tissue oxygen tension decreases in the arterial wall of the atherosclerotic region. Hypoxia inducible factor (HIF)-1α plays a critical role in the transcriptional activation of hypoxia inducible genes. However, the precise roles of HIF-1α independent pathways in hypoxic responses are largely unknown. Xanthine oxidase (XO) is an enzyme that utilizes molecular oxygen and produces reactive oxygen species (ROS). Here, we show that ROS derived from XO increases MMP-3, -10, and -13 expression in murine macrophages. We found that the transcript levels of macrophage MMP-3, -10, and -13 were increased in hypoxic conditions. Hypoxia induced MMP expression in HIF-1α deficient macrophages. N-acetylcysteine (NAC) or febuxostat, an XO inhibitor, suppressed MMP expression in murine macrophages. Febuxostat decreased the incidence of plaque rupture in apolipoprotein-E-deficient mice. Our results indicate that febuxostat stabilized atherosclerotic plaque via suppressing the activities of macrophage MMP-9 and -13. Febuxostat administration is a potential therapeutic option in the management of atherosclerotic patients.
Incidence of Autism Spectrum Disorder in Youths Affected by Gilles de la Tourette Syndrome Based on Data from a Large Single Italian Clinical Cohort
Authors: Gulisano Mariangela , Barone Rita , Mosa Maria Rita , Milana Maria Chiara , Saia Federica , Scerbo Miriam , Rizzo Renata
Published: November 2020

Gilles de la Tourette syndrome (GTS) and autism spectrum disorder (ASD) are etiologically related neurodevelopmental disorders with an onset age before 18 years and a reported comorbidity of 2.9–20%. The aim of the present study was to identify the incidence of ASD in a large clinical sample of individuals affected by GTS and to compare our results with previously reported incidences. We retrospectively analyzed clinical data (n = 1200) from January 2010 to March 2019 obtained from the outpatient Catania Tourette Clinic, part of the Child and Adolescent Neurology and Psychiatry of the Medical and Experimental Department of Catania University. We used internationally validated evaluation tools. The neuropsychological evaluation was carried out by an expert and a certificated team of child and adolescent neurologists, supervised by two expert child neurologists (R.R. and M.G.). We investigated 975 GTS-affected individuals of various socioeconomic levels aged 5–18 years, and 8.9% (n = 87) were affected by ASD. The incidence of GTS with ASD was significantly lower (p < 0.001) in children than in adolescents. No statistically significant differences were found in the sex distribution and age of onset of tics between individuals with GTS alone and those with GTS and ASD. The incidence of GTS and ASD comorbidity in this study was high, and this has several implications in terms of treatment and prognosis.
Methodology for Continuous Improvement Projects in Housing Constructions
Authors: del Solar Serrano Patricia , del Río Merino Mercedes , Villoria Sáez Paola
Published: November 2020

Several authors have studied construction defects, but no studies were found implementing best practices and control strategies through the implementation of continuous improvement projects. This article shows a procedure based on Continuous Improvement Projects, which can be used in building constructions, and it is structured into four phases: Plan, Do, Check, Act, following the PDCA Quality Cycle. In addition, the method developed was specified for ceramic tiling execution and was further implemented in three building projects of Spain. The results obtained concluded that the proposed Procedure can be used by construction professionals who are concerned about improving the quality of construction. In addition, the implementation of the Procedure managed to reduce around 45% the costs derived from the defects caused during the ceramic tiling execution, due to the best practices incorporated in the Procedure. A slight increase in the number of defects was also found, motivated by the thorough inspection conducted when the Procedure was applied. Therefore, the Procedure (incorporating the lessons learned) must be implemented so that by learning, gaining experience, and incorporating best practices, the goal of zero defects can be achieved.
Prognostic Interactions between FAP+ Fibroblasts and CD8a+ T Cells in Colon Cancer
Authors: Herrera Mercedes , Mezheyeuski Artur , Villabona Lisa , Corvigno Sara , Strell Carina , Klein Christian , Hölzlwimmer Gabriele , Glimelius Bengt , Masucci Giuseppe , Sjöblom Tobias , Östman Arne
Published: November 2020

Inter-case variations in immune cell and fibroblast composition are associated with prognosis in solid tumors, including colon cancer. A series of experimental studies suggest immune-modulatory roles of marker-defined fibroblast populations, including FAP-positive fibroblasts. These studies imply that the fibroblast status of tumors might affect the prognostic significance of immune-related features. Analyses of a population-based colon cancer cohort demonstrated good prognosis associations of FAP intensity and CD8a density. Notably, a significant prognostic interaction was detected between these markers (p = 0.013 in nonadjusted analyses and p = 0.003 in analyses adjusted for cofounding factors) in a manner where the good prognosis association of CD8 density was restricted to the FAP intensity-high group. This prognostic interaction was also detected in an independent randomized trial-derived colon cancer cohort (p = 0.048 in nonadjusted analyses). In the CD8-high group, FAP intensity was significantly associated with a higher total tumor density of FoxP3-positive immune cells and a higher ratio of epithelial-to-stromal density of CD8a T cells. The study presents findings relevant for the ongoing efforts to improve the prognostic performance of CD8-related markers and should be followed by additional validation studies. Furthermore, findings support, in general, earlier model-derived studies implying fibroblast subsets as clinically relevant modulators of immune surveillance. Finally, the associations between FAP intensity and specific immune features suggest mechanisms of fibroblast-immune crosstalk with therapeutic potential.
The Contribution of MicroRNAs to the Inflammatory and Neoplastic Characteristics of Erdheim–Chester Disease
Authors: Weissman Ran , Diamond Eli L. , Haroche Julien , Pillar Nir , Shapira Guy , Durham Benjamin H. , Buthorn Justin , Cohen Fleur , Ki Michelle , Stemer Galia , Ulaner Gary A. , Amoura Zahir , Emile Jean-François , Mazor Roei D. , Shomron Noam , Abdel-Wahab Omar I. , Shpilberg Ofer , Hershkovitz-Rokah Oshrat
Published: November 2020

The pathogenesis of histiocytic neoplasms is driven by mutations activating the MAPK/ERK pathway, but little is known about the transcriptional and post-transcriptional alterations involved in these neoplasms. We analyzed microRNA (miRNA) expression in plasma samples and tissue biopsies of Erdheim–Chester disease (ECD) and Langerhans cell histiocytosis (LCH) patients. In silico analysis revealed a potential role of miRNAs in regulating gene expression in these neoplasms as compared with healthy controls (HC). NanoString analysis revealed 101 differentially expressed plasma miRNAs in 16 ECD patients as compared with 11 HC, 95% of which were downregulated. MiRNAs-15a-5p, -15b-5p, -21-5p, -107, -221-3p, -320e, -630, and let-7 family miRNAs were further evaluated by qRT-PCR in an extended cohort of 32 ECD patients, seven LCH and 15 HC. Six miRNAs (let-7a, let-7c, miR-15a-5p, miR-15b-5p, miR-107 and miR-630) were highly expressed in LCH plasma and tissue samples as compared with ECD. Pathway enrichment analysis indicated the miRNA contribution to inflammatory and pro-survival signaling pathways. Moreover, the let-7 family members were downregulated in untreated ECD patients as compared with HC, while treatment with MAPK/ERK signaling inhibitors for 16 weeks resulted in their upregulation, which was in parallel with the radiologic response seen by PET-CT. The study highlights the potential contribution of miRNA to the inflammatory and neoplastic characteristics of ECD and LCH.
Correction: Liu, Y.-S.; et al. Inhibition of Protein Phosphatase 1 Stimulates Noncanonical ER Stress eIF2α Activation to Enhance Fisetin-Induced Chemosensitivity in HDAC Inhibitor-Resistant Hepatocellular Carcinoma Cells. Cancers 2019, 11, 918
Authors: Liu Yi-Sheng , Chang Yu-Chun , Kuo Wei-Wen , Chen Ming-Cheng , Hsu Hsi-Hsien , Tu Chuan-Chou , Yeh Yu-Lan , Viswanadha Vijaya Padma , Liao Po-Hsiang , Huang Chih-Yang
Published: November 2020

It has been reported that two sets of blot figures in Figure 3A,C looked identical in the original published paper [...]
Enhanced Carbon Dioxide Decomposition Using Activated SrFeO3−δ
Authors: Sim Jaeyong , Kim Sang-Hyeok , Kim Jin-Yong , Lee Ki Bong , Nam Sung-Chan , Park Chan Young
Published: November 2020

Today, climate change caused by global warming has become a worldwide problem with increasing greenhouse gas (GHG) emissions. Carbon capture and storage technologies have been developed to capture carbon dioxide (CO2); however, CO2 storage and utilization technologies are relatively less developed. In this light, we have reported efficient CO2 decomposition results using a nonperovskite metal oxide, SrFeCo0.5Ox, in a continuous-flow system. In this study, we report enhanced efficiency, reliability under isothermal conditions, and catalytic reproducibility through cyclic tests using SrFeO3−δ. This ferrite needs an activation process, and 3.5 vol% H2/N2 was used in this experiment. Activated oxygen-deficient SrFeO3−δ can decompose CO2 into carbon monoxide (CO) and carbon (C). Although SrFeO3−δ is a well-known material in different fields, no studies have reported its use in CO2 decomposition applications. The efficiency of CO2 decomposition using SrFeO3−δ reached ≥90%, and decomposition (≥80%) lasted for approximately 170 min. We also describe isothermal and cyclic experimental data for realizing commercial applications. We expect that these results will contribute to the mitigation of GHG emissions.
Glutamatergic Receptor Trafficking and Delivery: Role of the Exocyst Complex
Authors: Lira Matías , Mira Rodrigo G. , Carvajal Francisco J. , Zamorano Pedro , Inestrosa Nibaldo C. , Cerpa Waldo
Published: November 2020

Cells comprise several intracellular membrane compartments that allow them to function properly. One of these functions is cargo movement, typically proteins and membranes within cells. These cargoes ride microtubules through vesicles from Golgi and recycling endosomes to the plasma membrane in order to be delivered and exocytosed. In neurons, synaptic functions employ this cargo trafficking to maintain inter-neuronal communication optimally. One of the complexes that oversee vesicle trafficking and tethering is the exocyst. The exocyst is a protein complex containing eight subunits first identified in yeast and then characterized in multicellular organisms. This complex is related to several cellular processes, including cellular growth, division, migration, and morphogenesis, among others. It has been associated with glutamatergic receptor trafficking and tethering into the synapse, providing the molecular machinery to deliver receptor-containing vesicles into the plasma membrane in a constitutive manner. In this review, we discuss the evidence so far published regarding receptor trafficking and the exocyst complex in both basal and stimulated levels, comparing constitutive trafficking and long-term potentiation-related trafficking.
Reading between the (Genetic) Lines: How Epigenetics is Unlocking Novel Therapies for Type 1 Diabetes
Authors: Akil Ammira-Sarah AL-Shabeeb , Jerman Laila F. , Yassin Esraa , Padmajeya Sujitha S. , Al-Kurbi Alya , Fakhro Khalid A.
Published: November 2020

Type 1 diabetes (T1D) is an autoimmune condition where the body’s immune cells destroy their insulin-producing pancreatic beta cells leading to dysregulated glycaemia. Individuals with T1D control their blood glucose through exogenous insulin replacement therapy, often using multiple daily injections or pumps. However, failure to accurately mimic intrinsic glucose regulation results in glucose fluctuations and long-term complications impacting key organs such as the heart, kidneys, and/or the eyes. It is well established that genetic and environmental factors contribute to the initiation and progression of T1D, but recent studies show that epigenetic modifications are also important. Here, we discuss key epigenetic modifications associated with T1D pathogenesis and discuss how recent research is finding ways to harness epigenetic mechanisms to prevent, reverse, or manage T1D.
A Single Amino Acid Residue Regulates PTEN-Binding and Stability of the Spinal Muscular Atrophy Protein SMN
Authors: Rademacher Sebastian , Detering Nora T. , Schüning Tobias , Lindner Robert , Santonicola Pamela , Wefel Inga-Maria , Dehus Janina , Walter Lisa M. , Brinkmann Hella , Niewienda Agathe , Janek Katharina , Varela Miguel A. , Bowerman Melissa , Di Schiavi Elia , Claus Peter
Published: November 2020

Spinal Muscular Atrophy (SMA) is a neuromuscular disease caused by decreased levels of the survival of motoneuron (SMN) protein. Post-translational mechanisms for regulation of its stability are still elusive. Thus, we aimed to identify regulatory phosphorylation sites that modulate function and stability. Our results show that SMN residues S290 and S292 are phosphorylated, of which SMN pS290 has a detrimental effect on protein stability and nuclear localization. Furthermore, we propose that phosphatase and tensin homolog (PTEN), a novel phosphatase for SMN, counteracts this effect. In light of recent advancements in SMA therapies, a significant need for additional approaches has become apparent. Our study demonstrates S290 as a novel molecular target site to increase the stability of SMN. Characterization of relevant kinases and phosphatases provides not only a new understanding of SMN function, but also constitutes a novel strategy for combinatorial therapeutic approaches to increase the level of SMN in SMA.
Acid Sphingomyelinase Contributes to the Control of Mycobacterial Infection via a Signaling Cascade Leading from Reactive Oxygen Species to Cathepsin D
Authors: Wu Yuqing , Li Cao , Peng Huiming , Swaidan Ashraf , Riehle Andrea , Pollmeier Barbara , Zhang Yang , Gulbins Erich , Grassmé Heike
Published: November 2020

Tuberculosis, caused by Mycobacterium tuberculosis, is one of the most severe diseases worldwide. The initial pulmonary localization of the pathogen often develops into systemic infection with high lethality. The present work investigated the role of sphingolipids, specifically the function of acid sphingomyelinase (Asm) and ceramide, in infection of murine macrophages in vitro and mice in vivo with Mycobacterium bovis Bacillus Calmette-Guérin (BCG). In vitro, we investigated macrophages from wild-type (wt) and Asm deficient (Asm−/−) mice to define signaling events induced by BCG infection and mediated by Asm. We demonstrate that infection of wt macrophages results in activation of Asm, which increases reactive oxygen species (ROS) via stimulation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. ROS promote BCG degradation by cathepsin D. Asm deficiency in macrophages abrogates these effects. In vivo studies reveal that wt mice rapidly control BCG infection, while Asm−/− mice fail to control the infection and kill the bacteria. Transplantation of wt macrophages into Asm−/− mice reversed their susceptibility to BCG, demonstrating the importance of Asm in macrophages for defense against BCG. These findings indicate that Asm is important for the control of BCG infection.
Development of a Test-Bench for Evaluating the Embedded Implementation of the Improved Elephant Herding Optimization Algorithm Applied to Energy-Based Acoustic Localization
Authors: Correia Sérgio , Fé João , Tomic Slavisa , Beko Marko
Published: November 2020

The present work addresses the development of a test-bench for the embedded implementation, validity, and testing of the recently proposed Improved Elephant Herding Optimization (iEHO) algorithm, applied to the acoustic localization problem. The implemented methodology aims to corroborate the feasibility of applying iEHO in real-time applications on low complexity and low power devices, where three different electronic modules are used and tested. Swarm-based metaheuristic methods are usually examined by employing high-level languages on centralized computers, demonstrating their capability in finding global or good local solutions. This work considers iEHO implementation in C-language running on an embedded processor. Several random scenarios are generated, uploaded, and processed by the embedded processor to demonstrate the algorithm’s effectiveness and the test-bench usability, low complexity, and high reliability. On the one hand, the results obtained in our test-bench are concordant with the high-level implementations using MatLab® in terms of accuracy. On the other hand, concerning the processing time and as a breakthrough, the results obtained over the test-bench allow to demonstrate a high suitability of the embedded iEHO implementation for real-time applications due to its low latency.
Effect of Cavity Structure on Acoustic Characteristics of Phononic Crystals Based on Double-Layer Plates
Authors: Chen Chuanmin , Guo Zhaofeng , Liu Songtao , Feng Hongda , Qiao Chuanxi
Published: November 2020

Localized resonance phononic crystals (LRPCs) are increasingly attracting scientists’ attention in the field of low-frequency noise reduction because of the excellent subwavelength band gap characteristics in the low-frequency band. However, the LRPCs have always had the disadvantage that the noise reduction band is too narrow. In this paper, in order to solve this problem, LRPCs based on double-layer plates with cavity structures are designed. First, the energy bands of phononic crystals plate with different thicknesses were calculated by the finite element method (FEM). At the same time, the mechanism of band gap generation was analyzed in combination with the modalities. Additionally, the influence of structure on the sound transmission loss (STL) of the phononic crystals plate and the phononic crystals cavity plates were analyzed, which indicates that the phononic crystals cavity plates have notable characteristics and advantages. Moreover, this study reveals a unique ”cavity cave” pattern in the STL diagram for the phononic crystals cavity plates, and it was analyzed. Finally, the influence of structural factors on the band structure and STL of phononic crystals cavity plates are summarized, and the theoretical basis and method guidance for the study of phononic crystals cavity plates are provided. New ideas are also provided for the future design and research of phononic crystals plate along with potential applications in low-frequency noise reduction.
Developing an Introductory UAV/Drone Mapping Training Program for Seagrass Monitoring and Research
Authors: Yang Bo , Hawthorne Timothy L. , Hessing-Lewis Margot , Duffy Emmett J. , Reshitnyk Luba Y. , Feinman Michael , Searson Hunter
Published: November 2020

Unoccupied Aerial Vehicles (UAVs), or drone technologies, with their high spatial resolution, temporal flexibility, and ability to repeat photogrammetry, afford a significant advancement in other remote sensing approaches for coastal mapping, habitat monitoring, and environmental management. However, geographical drone mapping and in situ fieldwork often come with a steep learning curve requiring a background in drone operations, Geographic Information Systems (GIS), remote sensing and related analytical techniques. Such a learning curve can be an obstacle for field implementation for researchers, community organizations and citizen scientists wishing to include introductory drone operations into their work. In this study, we develop a comprehensive drone training program for research partners and community members to use cost-effective, consumer-quality drones to engage in introductory drone mapping of coastal seagrass monitoring sites along the west coast of North America. As a first step toward a longer-term Public Participation GIS process in the study area, the training program includes lessons for beginner drone users related to flying drones, autonomous route planning and mapping, field safety, GIS analysis, image correction and processing, and Federal Aviation Administration (FAA) certification and regulations. Training our research partners and students, who are in most cases novice users, is the first step in a larger process to increase participation in a broader project for seagrass monitoring in our case study. While our training program originated in the United States, we discuss our experiences for research partners and communities around the globe to become more confident in introductory drone operations for basic science. In particular, our work targets novice users without a strong background in geographic research or remote sensing. Such training provides technical guidance on the implementation of a drone mapping program for coastal research, and synthesizes our approaches to provide broad guidance for using drones in support of a developing Public Participation GIS process.
Horizon Thermodynamics in D-Dimensional f(R) Black Hole
Authors: Zhu Chenrui , Yang Rong-Jia
Published: November 2020

We consider whether the new horizon-first law works in higher-dimensional f(R) theory. We firstly obtain the general formulas to calculate the entropy and the energy of a general spherically-symmetric black hole in D-dimensional f(R) theory. For applications, we compute the entropies and the energies of some black hokes in some interesting higher-dimensional f(R) theories.
Information Theory for Data Communications and Processing
Authors: (Shitz) Shlomo Shamai , Zaidi Abdellatif
Published: November 2020

This book, composed of the collection of papers that have appeared in the Special Issue of theEntropy journal dedicated to “Information Theory for Data Communications and Processing”,reflects, in its eleven chapters, novel contributions based on the firm basic grounds of informationtheory. The book chapters [1–11] address timely theoretical and practical aspects that carry bothinteresting and relevant theoretical contributions, as well as direct implications for modern currentand future communications systems. [...]
A Low-Cost Platform for Modeling and Controlling the Yaw Dynamics of an Agricultural Tractor to Gain Autonomy
Authors: Pérez Sergio Sandoval , López Juan Miguel González , Jimenez Betancourt Ramón O. , Villalvazo Laureano Efraín , Solís Jesús Ezequiel Molinar , Sánchez Cervantes María Guadalupe , Ochoa Guzmán Víctor Javier
Published: November 2020

In this study, a low-cost proposed platform for training dynamics (PPTD) is proposed based on operational amplifiers to understand the dynamics and variables of the agricultural tractor John Deere tractor model 4430 to gain autonomy and analyze the behavior of control algorithms proposed in real time by state feedback. The proposed platform uses commercial sensors and interacts with the Arduino Uno and/or Daq-6009 board from National Instruments. A mobile application (APP) was also developed for real-time monitoring of autonomous control signals, the local reference system, and physical and dynamic variables in the tractor; this platform can be used as a mobile alternative applied to a tractor in physically installed form. In the presented case, the PPTD was mounted on a John Deere tractor to test its behavior; moreover, it may be used on other tractor models similarly as established here. The established results of this platform were compared with models established in MATLAB, validating the proposal. All simulations and developments are shared through a web-link as open-source files so that anyone with basic knowledge of electronics and modeling of vehicles can reproduce the proposed platform.
Survey of Countering DoS/DDoS Attacks on SIP Based VoIP Networks
Authors: Nazih Waleed , Elkilani Wail S. , Dhahri Habib , Abdelkader Tamer
Published: November 2020

Voice over IP (VoIP) services hold promise because of their offered features and low cost. Most VoIP networks depend on the Session Initiation Protocol (SIP) to handle signaling functions. The SIP is a text-based protocol that is vulnerable to many attacks. Denial of Service (DoS) and distributed denial of service (DDoS) attacks are the most harmful types of attacks, because they drain VoIP resources and render SIP service unavailable to legitimate users. In this paper, we present recently introduced approaches to detect DoS and DDoS attacks, and classify them based on various factors. We then analyze these approaches according to various characteristics; furthermore, we investigate the main strengths and weaknesses of these approaches. Finally, we provide some remarks for enhancing the surveyed approaches and highlight directions for future research to build effective detection solutions.
Optimization of Log-Periodic TV Reception Antenna with UHF Mobile Communications Band Rejection
Authors: Mistry Keyur K. , Lazaridis Pavlos I. , Zaharis Zaharias D. , Chochliouros Ioannis P. , Loh Tian Hong , Gravas Ioannis P. , Cheadle David
Published: November 2020

The coexistence of TV broadcasting and mobile services causes interference that leads to poor quality-of-service for TV consumers. Solutions usually found in the market involve external band-stop filters along with TV reception log-periodic and Yagi-Uda antennas. This paper presents a log-periodic antenna design without additional filtering that serves as a lower cost alternative to avoid interference from mobile services into the UHF TV. The proposed antenna operates in the UHF TV band (470–790 MHz-passband) and rejects the 800 MHz and 900 MHz bands (stopband) of 4G/LTE-800 and GSM900 services, respectively. Matching to 50 Ohms is very satisfactory in the passband with values of S11 below −12 dB. Furthermore, the antenna is highly directive with a realized gain of approximately 8 dBi and a front-to-back ratio greater than 20 dB.
A Fully Open Source Remote Laboratory for Practical Learning
Authors: Letowski Bastien , Lavayssière Camille , Larroque Benoît , Schröder Martin , Luthon Franck
Published: November 2020

Nowadays, communication and web services are part of our lives, including education, and e-learning applications are used more and more. However, teaching in engineering sciences requires an important amount of practical experiments. Hence, remote laboratories are an attractive solution, offering new tools for both teachers and learners. Our objective is to propose a fully open source remote laboratory for generic practice, in all fields of engineering education or applied sciences. This work is based on an open source Supervisory Control and a Data Acquisition platform programmed with Python. Interoperability is one of the main issues considered here to ensure a wide compatibility with multi-communication protocols and multi-instruments used in practical labwork.
A Low-Cost Current Sensor Based on Semi-Cylindrical Magnetostrictive Composite
Authors: Xu Shaoyi , Peng Qiang , Xing Fangfang , Xue Hongyu , Sun Junwen , Ma Lei , Li Ming
Published: November 2020

This paper presents the design, fabrication, and characterization of a compact current sensor based on magnetostrictive composites and resistance strain gauges. Firstly, we designed three kinds of current sensors with different structures, in which the shape of the giant magnetostrictive material (GMM) was cuboid, cylindrical, and semi-cylindrical. A set of finite element method (FEM) simulations were performed to qualitatively guide the design of three prototypes of the current sensor. It was determined that the most ideal shape of the GMM was semi-cylindrical. Secondly, Terfenol-D (TD) powder and epoxy resin were mixed to prepare magnetostrictive composites. In this paper, magnetostrictive composites with different particle size ranges and mass ratio were prepared and tested. The results show that the magnetostrictive composites had the best performance when the particle size range was 149–500 μm and the mass ratio of epoxy resin to TD powder was 1:5. Finally, this paper tested the performance of the sensor. The sensitivity, repeatability, and linear working range of the sensor reached 0.104 με/A, 2.51%, and 100–900 A respectively, when only 0.31 g of TD powder was employed. This means that current measurement with low cost, high sensitivity, and wide range was realized.
Hydrodynamic Performance of a Hybrid System Combining a Fixed Breakwater and a Wave Energy Converter: An Experimental Study
Authors: Peng Wei , Zhang Yingnan , Yang Xueer , Zhang Jisheng , He Rui , Liu Yanjun , Chen Renwen
Published: November 2020

In this paper, a hybrid system integrating a fixed breakwater and an oscillating buoy type wave energy converter (WEC) is introduced. The energy converter is designed to extract the wave power by making use of the wave-induced heave motions of the three floating pontoons in front of the fixed breakwater. A preliminary experimental study is carried out to discuss the hydrodynamic performance of the hybrid system under the action of regular waves. A scale model was built in the laboratory at Hohai University, and the dissipative force from racks and gearboxes and the Ampere force from dynamos were employed as the power take-off (PTO) damping source. During the experiments, variations in numbers of key parameters, including the wave elevation, free response or damped motion of the floating pontoons, and the voltage output of the dynamos were simultaneously measured. Results indicate that the wave overtopping and breaking occurring on the upper surfaces of floating pontoons have a significant influence on the hydrodynamic performance of the system. For moderate and longer waves, the developed system proves to be effective in attenuating the incident energy, with less than 30% of the energy reflected back to the paddle. More importantly, the hydrodynamic efficiency of energy conversion for the present device can achieve approximately 19.6% at the lowest wave steepness in the model tests, implying that although the WEC model harnesses more energy in more energetic seas, the device may be more efficient for wave power extraction in a less energetic sea-state.
Decompositions for MPC of Linear Dynamic Systems with Activation Constraints
Authors: Valderrama Bento da Silva Pedro Henrique , Camponogara Eduardo , Seman Laio Oriel , Villarrubia González Gabriel , Reis Quietinho Leithardt Valderi
Published: November 2020

The interconnection of dynamic subsystems that share limited resources are found in many applications, and the control of such systems of subsystems has fueled significant attention from scientists and engineers. For the operation of such systems, model predictive control (MPC) has become a popular technique, arguably for its ability to deal with complex dynamics and system constraints. The MPC algorithms found in the literature are mostly centralized, with a single controller receiving the signals and performing the computations of output signals. However, the distributed structure of such interconnected subsystems is not necessarily explored by standard MPC. To this end, this work proposes hierarchical decomposition to split the computations between a master problem (centralized component) and a set of decoupled subproblems (distributed components) with activation constraints, which brings about organizational flexibility and distributed computation. Two general methods are considered for hierarchical control and optimization, namely Benders decomposition and outer approximation. Results are reported from a numerical analysis of the decompositions and a simulated application to energy management, in which a limited source of energy is distributed among batteries of electric vehicles.
Heat Transfer Performance of an Axially Rotating Heat Pipe for Cooling of Grinding
Authors: Chen Jiajia , Jiang Huafei , Fu Yucan , Qian Ning
Published: November 2020

Coolants are widely used to dissipate grinding heat in conventional grinding. This process, however, is not satisfactory as coolants often lose efficacy in grinding due to film boiling and can result in adverse health and environment effects. The present paper put forward the concept of a rotating heat pipe grinding wheel, attempting to reduce or eliminate the coolant amount and realize green machining. The heat transfer performance of rotating heat pipe grinding wheel was studied by using volume of fluid method in ANSYS/FLUENT. The influence of the input heat flux, filling ratio and rotational speed were investigated by a simulation method. Results show that the appropriate heat flux range for the rotating heat pipe grinding wheel was from 2000 to 100,000 W/m2, the ideal filling ratio was 50% and the rise of the rotational speed turned out to weaken the heat transfer coefficient. Finally, dry grinding experiments on Ti-6Al-4V were performed and the temperatures in both the rotating heat pipe and the grinding contact zone were monitored. The new designed rotating heat pipe grinding wheel showed a good prospect for application to green grinding of difficult-to-cut materials.
Prediction of Novel Humified Gas Turbine Cycle Parameters for Ammonia/Hydrogen Fuels
Authors: Božo Milana Guteša , Valera-Medina Agustin
Published: November 2020

Carbon emissions reduction via the increase of sustainable energy sources in need of storage defines chemicals such as ammonia as one of the promising solutions for reliable power decarbonisation. However, the implementation of ammonia for fuelling purposes in gas turbines for industry and energy production is challenging when compared to current gas turbines fuelled with methane. One major concern is the efficiency of such systems, as this has direct implications in the profitability of these power schemes. Previous works performed around parameters prediction of standard gas turbine cycles showed that the implementation of ammonia/hydrogen as a fuel for gas turbines presents very limited overall efficiencies. Therefore, this paper covers a new approach of parameters prediction consisting of series of analytical and numerical studies used to determine emissions and efficiencies of a redesigned Brayton cycle fuelled with humidified ammonia/hydrogen blends. The combustion analysis was done using CHEMKIN-PRO (ANSYS, Canonsburg, PA, USA), and the results were used for determination of the combustion efficiency. Chemical kinetic results denote the production of very low NOx as a consequence of the recombination of species in a post combustion zone, thus delivering atmospheres with 99.2% vol. clean products. Further corrections to the cycle (i.e., compressor and turbine size) followed, indicating that the use of humidified ammonia-hydrogen blends with a total the amount of fuel added of 10.45 MW can produce total plant efficiencies ~34%. Values of the gas turbine cycle inlet parameters were varied and tested in order to determine sensibilities to these modifications, allowing changes of the analysed outlet parameters below 5%. The best results were used as inputs to determine the final efficiency of an improved Brayton cycle fuelled with humidified ammonia/hydrogen, reaching values up to 43.3% efficiency. It was notorious that humidification at the injector was irrelevant due to the high water production (up to 39.9%) at the combustion chamber, whilst further research is recommended to employ the unburned ammonia (0.6% vol. concentration) for the reduction of NOx left in the system (~10 ppm).
LES Analysis of CO Emissions from a High Pressure Siemens Gas Turbine Prototype Combustor at Part Load
Authors: Gruhlke Pascal , Beck Christian , Janus Bertram , Kempf Andreas M.
Published: November 2020

This work contributes to the understanding of mechanisms that lead to increased carbon monoxide (CO) concentrations in gas turbine combustion systems. Large-eddy simulations (LES) of a full scale high pressure prototype Siemens gas turbine combustor at three staged part load operating conditions are presented, demonstrating the ability to predict carbon monoxide pollutants from a complex technical system by investigating sources of incomplete CO oxidation. Analytically reduced chemistry is applied for the accurate pollutant prediction together with the dynamic thickened flame model. LES results show that carbon monoxide emissions at the probe location are predicted in good agreement with the available test data, indicating two operating points with moderate pollutant levels and one operating point with CO concentrations below 10 ppm. Large mixture inhomogeneities are identified in the combustion chamber for all operating points. The investigation of mixture formation indicates that fuel-rich mixtures mainly emerge from the pilot stage resulting in high equivalence ratio streaks that lead to large CO levels at the combustor outlet. Flame quenching due to flame-wall-interaction are found to be of no relevance for CO in the investigated combustion chamber. Post-processing with Lagrangian tracer particles shows that cold air—from effusion cooling or stages that are not being supplied with fuel—lead to significant flame quenching, as mixtures are shifted to leaner equivalence ratios and the oxidation of CO is inhibited.
Aerodynamic Analysis of Coning Effects on the DTU 10 MW Wind Turbine Rotor
Authors: Sun Zhenye , Zhu Wei Jun , Shen Wen Zhong , Zhong Wei , Cao Jiufa , Tao Qiuhan
Published: November 2020

The size of wind turbine rotors is still rapidly increasing, though many technical challenges emerge. Novel rotor designs emerge to satisfy this up-scale trend, such as downwind load-aligned concepts, which orients the loads along the blade spanwise to greatly decrease the bending moments at the root. As the studies on the aerodynamics of these rotor concepts using 3D body-fitted mesh are very limited, this paper establishes different cone configurations based on the DTU 10 MW reference rotor and conducts a series of simulations. It is found that the cone angle and the distance from the blade section to the tip vortex are two deterministic factors on conning. Upwind rotors have larger power output, less thrust, smaller wake deficit, and smaller influencing area than downwind rotors of the same size, which provides superior aerodynamic priority and benefits wind farm design. The largest upwind cone angle of 14.03°, among the cases studied, leads to the highest torque to thrust ratio which is 3.63% higher than the baseline rotor. The downwind load-aligned rotor, designed to reduce the blade root bending moments at large wind speed, performs worse at the present simulation conditions than an upwind rotor of the same size.
Resonant Combustion Start Considering Potential Energy of Free-Piston Engine Generator
Authors: Sato Mitsuhide , Goto Takumi , Zheng Jianping , Irie Shoma
Published: November 2020

Free-piston engine generators without a crank mechanism are expected to be used in series hybrid vehicles because of their lower losses. The series hybrid system requires a low starting thrust because the engine frequently starts depending on the battery state. This study clarifies the effectiveness of the constant thrust resonance starting method that utilizes the compression pressure of the engine and the spring thrust. The piston must pass the combustion starting point with a predetermined speed to start combustion. Herein, we present a thrust setting method that uses the energy state diagram to optimize the velocity at the combustion start point. A simulation is performed assuming output when mounted on a vehicle. Consequently, the simulation results show that the maximum thrust can be reduced by more than 90% compared to that without resonance. Moreover, the speed at the combustion start point is in agreement with the value obtained using an energy state diagram. An impulse-like combustion pressure is generated in 180 ms, and combustion can be started using resonance, as shown in an experiment using a small-output engine and linear motor. The effectiveness of the constant thrust resonance starting method was confirmed.
The Potential of Agricultural Biogas Production in Ukraine—Impact on GHG Emissions and Energy Production
Authors: Wąs Adam , Sulewski Piotr , Krupin Vitaliy , Popadynets Nazariy , Malak-Rawlikowska Agata , Szymańska Magdalena , Skorokhod Iryna , Wysokiński Marcin
Published: November 2020

Renewable energy production is gaining importance in the context of global climate changes. However, in some countries other aspects increasing the role of renewable energy production are also present. Such a country is Ukraine, which is not self-sufficient in energy supply and whose dependency on poorly diversified import of energy carriers regularly leads to political tensions and has socio-economic implications. Production of agricultural biogas seems to be a way to both slow down climatic changes and increase energy self-sufficiency by replacing or complementing conventional sources of energy. One of the most substantial barriers to agricultural biogas production is the low level of agricultural concentration and significant economies of scale in constructing biogas plants. The aim of the paper was thus to assess the potential of agricultural biogas production in Ukraine, including its impact on energy self-sufficiency, mitigation of greenhouse gas (GHG) emissions and the economic performance of biogas plants. The results show that due to the prevailing fragmentation of farms, most manure cannot be processed in an economically viable way. However, in some regions utilization of technically available manure for agricultural biogas production could cover up to 11% of natural gas or up to 19% of electricity demand. While the theoretical potential for reducing greenhouse gas emissions could reach 5% to 6.14%, the achievable technical potential varies between 2.3% and 2.8% of total emissions. The economic performance of agricultural biogas plants correlates closely with their size and bioenergy generation potential.
Robust Decentralized Tracking Voltage Control for Islanded Microgrids by Invariant Ellipsoids
Authors: Soliman Hisham , Bayoumi Ehab , Al-Hinai Amer , Soliman Mostafa
Published: November 2020

This manuscript presents a robust tracking (servomechanism) controller for linear time-invariant (LTI) islanded (autonomous, isolated) microgrid voltage control. The studied microgrid (MG) consists of many distributed energy resources (DERs) units, each using a voltage-sourced converter (VSC) for the interface. The optimal tracker design uses the ellipsoidal approximation to the invariant sets. The MG system is decomposed into different subsystems (DERs). Each subsystem is affected by the rest of the system that is considered as a disturbance to be rejected by the controller. The proposed tracker (state feedback integral control) rejects bounded external disturbances by minimizing the invariant ellipsoids of the MG dynamics. A condition to design decentralized controllers is derived in the form of linear matrix inequalities. The proposed controller is characterized by rapid transient response, and zero error in the steady state. A robustness analysis of the control strategy (against load changes, load unbalances, etc.) is carried out. A MATLAB/SimPowerSystems (R2017b, MathWorks, Natick, MA, USA) simulation of the case study confirm the robustness of the proposed controller.
The Identification of Hotspots in the Bioenergy Production Chain
Authors: Muradin Magdalena , Kulczycka Joanna
Published: November 2020

Increasing interest in bioenergy production in the context of the transition towards a circular economy and the promotion of renewable energy has produced demands for optimization of the value chain of energy production to improve the environmental viability of the system. Hotspot analysis based on life cycle assessment (LCA) contributes to the mitigation of environmental burdens and is a very important step towards the implementation of a bioeconomy strategy. In this study, hotspots identified using two parallel pathways: a literature review and empirical research on four different biogas plants located in Poland. LCA and energy return on investment (EROI) analysis of the whole bioenergy production chain were considered to identify unit processes or activities that are highly damaging to the environment. The biogas plants differ mainly in the type of raw materials used as an input and in the method of delivery. The results show that the most impactful processes are those in the delivery of biomass, especially road transport by tractor. The second contributor was crop cultivation, where fossil fuels are also used. Although the EROI analysis indicates a negligible impact of transport on the energy efficiency of bioenergy plants, the environmental burden of biomass transportation should be taken into consideration when planning further measures to support the development of the bioeconomy.