bluuebunny/crossref_metadata_2025 huggingface dataset:
Influences of Growth Species and Inclusions on the Current–Voltage Behavior of Plasma Electrolytic Oxidation: A Review
Authors: Tsai Dah-Shyang , Chou Chen-Chia
Published: February 2021

Plasma electrolytic oxidation (PEO) has attracted increasing attention since the transportation industry adopts more lightweight metal components and requires an improved version of anodizing for surface protection. In response to the demand, researchers enrich the technical connotation of PEO through diversifying the growth paths and adopting new precursors. Foreign electrolyte additives, involving ceramic and polymeric particles, organic dye emulsions, are incorporated to accomplish various goals. On the other hand, significant progress has been made on comprehension of softening sparks; denoting the adverse trend of growing discharge intensity can be re-routed by involving cathodic current. I–V response shows the cathodic pulse current not only cools down the ensuing anodic pulse, but also twists the coating conductivity, and the residuals of twists accumulate over a long time frame, plausibly through oxide protonation. Thus, the cathodic current provides a tool to control the discharge intensity via integration of the coating conductivity deviations. So far, these cathodic current studies have been performed in the electrolytes of KOH and Na2SiO3. When exotic additives are included, for example Cr2O3, the cathodic current effect is also shifted, as manifested in remarkable changes in its current–voltage (I–V) behavior. We anticipate the future study on cathodic current influences of inclusion shall lead to a precise control of micro arc.
Role of Melatonin in Bone Remodeling around Titanium Dental Implants: Meta-Analysis
Authors: López-Valverde Nansi , Pardal-Peláez Beatriz , López-Valverde Antonio , Ramírez Juan Manuel
Published: February 2021

The theory, known as the “brain-bone axis” theory, involves the central nervous system in bone remodeling. The alteration of the nervous system could lead to abnormal bone remodeling. Melatonin produced by the pineal gland is a hormone that is characterized by its antioxidant properties. The aim of this meta-analysis was to examine the role of melatonin in the growth of new bone around titanium dental implants in vivo. A manual search of the PubMed and Web of Science databases was conducted to identify scientific studies published until November 2020. We included randomized clinical trials (RCTs) and animal studies where melatonin was used with titanium implants. Fourteen studies met the inclusion criteria. Quality was assessed using the Jadad scale and SYRCLE’s risk of bias tool. Our meta-analysis revealed that the use of melatonin during implant placement improves bone-to-implant contact percentages in animals (difference of means, random effects: 9.59 [95% CI: 5.53–13.65]), reducing crestal bone loss in humans (difference in means, random effects: −0.55 [95% CI: 1.10–0.00]). In animals, titanium implants using melatonin increase bone-to-implant contact surface 2–6 weeks after their placement and reduce crestal bone loss in humans following six months. The results of this meta-analysis should be taken with caution, due to the small samples and the large heterogeneity among studies.
Comparative Analysis of the Shear Bond Strength of Flowable Self-Adhering Resin-Composites Adhesive to Dentin with a Conventional Adhesive
Authors: Asiri Abdulmajeed Ali , Khan Rawaiz , Alzahrani Sultan Saeed , Haider Sajjad , Khan Salah Ud-Din , Asiri Essa Ali Mousa , Alamri Maha Fayez , Ahmad Ashfaq , Mubushar Muhammad
Published: February 2021

This study aimed to measure and compare the shear bond strength (SBS) of a self-adhering flowable resin composite to dentin with a conventional flowable composite, and evaluate the various modes of failure. Thirty human premolar teeth (n = 30) were randomly allocated to two groups (Group I: Vertise™ Flow; Group II: Filtek Ultimate + Single Bond Universal) of 15 specimens each, and SBS was measured for specimens from each group by applying a shear load using a universal testing machine (UTM). Modes of failure were observed with an optical microscope. An independent-samples T-test was performed to test Levene’s assumption of homogeneity of variance across both groups, with the critical value set at 0.05. The results revealed, that the self-adhering flowable composite (Group I: Vertise™ Flow) resulted in a lower shear bond strength compared with the conventional adhesive system composite (Group II: Filtek Ultimate + Single Bond Universal). Moreover, group I predominantly exhibited non-cohesive failure, which reflects poor bonding to dentin. On the other hand, Group II showed mixed failure for most of the samples, which demonstrated strong adhesive bonding. Therefore, it could be concluded that the self-adhering flowable resin composite (Group I) results in lower SBS to dentin compared with a conventional adhesive system.
Resistance to Molten Superalloy at 1550 °C for Molybdenum Metal Core with a Silica/Silicide Coating
Authors: Zhang Chong , Liu Enze , Zheng Zhi , Ning Likui , Tong Jian , Tan Zheng , Li Haiying
Published: February 2021

This work designs a silica (SiO2) layer on a molybdenum metal core to provide new insights on the corrosion resistance of the silica/silicide coating in the Ni-based superalloy. The molybdenum substrate coated with MoSi2 by pack cementation was pre-oxidized to fabricate a cristobalite scale on the surface and the preoxidation specimens were chosen to examine the corrosion-resistant property by using a DSM11 superalloy at 1550 °C. In order to prepare a cristobalite layer, the microstructure evolution of a 40- µm MoSi2 coating with the different oxidation parameters (temperature and time) was investigated. After casting test, the different casting results showed that the silicide layer was dissolved in the molten superalloy. However, the molybdenum matrix was found to be protected by the cristobalite layer, as well as accompanied by the cristobalite layer partially destroyed at the core/superalloy interfaces. Furthermore, the reason for the destruction of cristobalite layer was analyzed. The failure mechanism of the cristobalite layer was proposed during the cast process.
Direct-ARPES and STM Investigation of FeSe Thin Film Growth by Nd:YAG Laser
Authors: Chaluvadi Sandeep , Mondal Debashis , Bigi Chiara , Fujii Jun , Adhikari Rajdeep , Ciancio Regina , Bonanni Alberta , Panaccione Giancarlo , Rossi Giorgio , Vobornik Ivana , Orgiani Pasquale
Published: February 2021

Research on ultrathin quantum materials requires full control of the growth and surface quality of the specimens in order to perform experiments on their atomic structure and electron states leading to ultimate analysis of their intrinsic properties. We report results on epitaxial FeSe thin films grown by pulsed laser deposition (PLD) on CaF2 (001) substrates as obtained by exploiting the advantages of an all-in-situ ultra-high vacuum (UHV) laboratory allowing for direct high-resolution surface analysis by scanning tunnelling microscopy (STM), synchrotron radiation X-ray photoelectron spectroscopy (XPS) and angle-resolved photoemission spectroscopy (ARPES) on fresh surfaces. FeSe PLD growth protocols were fine-tuned by optimizing target-to-substrate distance d and ablation frequency, atomically flat terraces with unit-cell step heights are obtained, overcoming the spiral morphology often observed by others. In-situ ARPES with linearly polarized horizontal and vertical radiation shows hole-like and electron-like pockets at the Γ and M points of the Fermi surface, consistent with previous observations on cleaved single crystal surfaces. The control achieved in growing quantum materials with volatile elements such as Se by in-situ PLD makes it possible to address the fine analysis of the surfaces by in-situ ARPES and XPS. The study opens wide avenues for the PLD based heterostructures as work-bench for the understanding of proximity-driven effects and for the development of prospective devices based on combinations of quantum materials.
A Sensitive Data Access Model in Support of Learning Health Systems
Authors: Ecarot Thibaud , Fraikin Benoît , Lavoie Luc , McGilchrist Mark , Ethier Jean-François
Published: February 2021

Given the ever-growing body of knowledge, healthcare improvement hinges more than ever on efficient knowledge transfer to clinicians and patients. Promoted initially by the Institute of Medicine, the Learning Health System (LHS) framework emerged in the early 2000s. It places focus on learning cycles where care delivery is tightly coupled with research activities, which in turn is closely tied to knowledge transfer, ultimately injecting solid improvements into medical practice. Sensitive health data access across multiple organisations is therefore paramount to support LHSs. While the LHS vision is well established, security requirements to support them are not. Health data exchange approaches have been implemented (e.g., HL7 FHIR) or proposed (e.g., blockchain-based methods), but none cover the entire LHS requirement spectrum. To address this, the Sensitive Data Access Model (SDAM) is proposed. Using a representation of agents and processes of data access systems, specific security requirements are presented and the SDAM layer architecture is described, with an emphasis on its mix-network dynamic topology approach. A clinical application benefiting from the model is subsequently presented and an analysis evaluates the security properties and vulnerability mitigation strategies offered by a protocol suite following SDAM and in parallel, by FHIR.
On the Kinetic Energy Driven Superconductivity in the Two-Dimensional Hubbard Model
Authors: Yanagisawa Takashi , Yamaji Kunihiko , Miyazaki Mitake
Published: February 2021

We investigate the role of kinetic energy for the stability of superconducting state in the two-dimensional Hubbard model on the basis of an optimization variational Monte Carlo method. The wave function is optimized by multiplying by correlation operators of site off-diagonal type. This wave function is written in an exponential-type form given as ψλ=exp(−λK)ψG for the Gutzwiller wave function ψG and a kinetic operator K. The kinetic correlation operator exp(−λK) plays an important role in the emergence of superconductivity in large-U region of the two-dimensional Hubbard model, where U is the on-site Coulomb repulsive interaction. We show that the superconducting condensation energy mainly originates from the kinetic energy in the strongly correlated region. This may indicate a possibility of high-temperature superconductivity due to the kinetic energy effect in correlated electron systems.
In-Situ Formed Al3Zr Compounds Reinforced Al Composites and Tribological Application
Authors: Umeda Junko , Nishimura Nodoka , Fujii Hiroko , Jia Lei , Kondoh Katsuyoshi
Published: February 2021

An Al3Zr-reinforced Al matrix composite using metal powders was fabricated via in-situ synthesis in vacuum; these were subjected to a pin-on-disc wear test with a SUS304 disc specimen under oil lubrication. The elemental mixture of Al and ZrH2 particles was sintered in vacuum for the in-situ-formed Al3Zr. ZrH2 particles were thermally decomposed in the reaction with the Al matrix to form hard Al3Zr intermetallic compounds. The friction coefficient and wear volume values of the Al–Al3Zr composites were significantly lower than those of the pure Al specimen. This is attributed to the uniform dispersion of Al3Zr particles in the Al matrix, which prevented the metallurgical bond from falling and blocked the direct contact between the Al matrix and SUS304 disc.
Rare Earths Doped Materials
Authors: Milanova Maria , Tsvetkov Martin
Published: February 2021

Тhe properties of the Rare Earth Elements allow a wide range of applications in optoelectronics, fiber amplifiers, solid-state lasers, telecommunications, biosensing, and photocatalysis, just to mention a few [...]
Growth of High Quality GaN on Si (111) Substrate by Using Two-Step Growth Method for Vertical Power Devices Application
Authors: Lee Jae-Hoon , Im Ki-Sik
Published: February 2021

A crack-free GaN film grown on 4-inch Si (111) substrate is proposed using two-step growth methods simply controlled by both III/V ratio and pressure. Two-step growth process is found to be effective in compensating the strong tensile stress in the GaN layer grown on Si substrate. The high-resolution X-ray diffraction (XRD) rocking curves of (002) and (102) planes for the GaN epitaxial layer with two-step growth method are 317 and 432 arcsec, while the corresponding values for the reference sample without two-step growth method are 550 and 1207 arcsec, respectively. The reduced threading dislocation of GaN film with two-step growth method is obtained to be ~2 × 108/cm2, which is attributed to effectively annihilate and bend threading dislocation.
Flux Method Growth of Large Size Group IV–V 2D GeP Single Crystals and Photoresponse Application
Authors: Zhao Shuqi , Yu Tongtong , Wang Ziming , Wang Shilei , Wei Limei , Chen Xiaohua , Wang Shanpeng
Published: February 2021

Two-dimensional (2D) materials driven by their unique electronic and optoelectronic properties have opened up possibilities for their various applications. The large and high-quality single crystals are essential to fabricate high-performance 2D devices for practical applications. Herein, IV-V 2D GeP single crystals with high-quality and large size of 20 × 15 × 5 mm3 were successfully grown by the Bi flux growth method. The crystalline quality of GeP was confirmed by high-resolution X-ray diffraction (HRXRD), Laue diffraction, electron probe microanalysis (EPMA) and Raman spectroscopy. Additionally, intrinsic anisotropic optical properties were investigated by angle-resolved polarized Raman spectroscopy (ARPRS) and transmission spectra in detail. Furthermore, we fabricated high-performance photodetectors based on GeP, presenting a relatively large photocurrent over 3 mA. More generally, our results will significantly contribute the GeP crystal to the wide optoelectronic applications.
Clinician Perspectives of COVID-19-Related Cancer Drug Funding Measures in Ontario
Authors: Naipaul Rohini D. , Mercer Rebecca E. , Chan Kelvin K. W. , Yeung Lyndee , Forbes Leta , Gavura Scott
Published: February 2021

The COVID-19 pandemic has a significant impact on cancer patients and the delivery of cancer care. To allow clinicians to adapt treatment plans for patients, Ontario Health (Cancer Care Ontario) issued a series of interim funding measures for the province’s New Drug Funding Program (NDFP), which covers the cost of most hospital-delivered cancer drugs. To assess the utility of the measures and the need for their continuation, we conducted an online survey of Ontario oncology clinicians. The survey was open 3–25 September 2020 and generated 105 responses. Between April and June 2020, 46% of respondents changed treatment plans for more than 25% of their cancer patients due to the pandemic. Clinicians report broad use of interim funding measures. The most frequently reported strategies used were treatment breaks for stable patients (62%), extending dosing intervals (59%), and deferring routine imaging (56%). Most clinicians anticipate continuing to use these interim funding measures in the coming months. The survey showed that adapting cancer drug funding policies has supported clinical care in Ontario during the pandemic.
Anti-PD-1-Induced Hidradenitis Suppurativa
Authors: Maillard Alexia , Pastor Damien , Merat Rastine
Published: February 2021

Mucocutaneous adverse events are commonly observed under immune checkpoint inhibitors (ICIs) therapy. Here, we report the case of a 43-year-old male patient with a stage IIIC melanoma disease who developed hidradenitis suppurativa (HS) three months after the beginning of an anti-PD-1 (nivolumab) adjuvant therapy. The patient had no comorbidities other than obesity and severe acne during adolescence. After an unsuccessful course of lymecycline while he was still treated with nivolumab, he gradually improved under zinc gluconate therapy and, more importantly, after nivolumab cessation. HS is a recurrent follicular inflammatory disease in the apocrine gland-bearing areas of the body often associated with obesity, metabolic syndrome, tobacco smoking, inflammatory bowel diseases, psoriasis, and arthritis. In our patient, the latency period between drug initiation and onset of HS symptoms and the improvement after immunotherapy discontinuation, argued strongly in favor of an anti-PD-1-induced HS. Anti-PD-1 therapies often trigger T cells-mediated adverse events that mimic Th17-mediated inflammatory and neutrophilic diseases. We suggest that HS, as other pustular skin reactions and ICIs-induced neutrophilic colitis, can be part of the anti-PD-1 mucocutaneous adverse event spectrum.
Introduction of the Grayscale Median for Ultrasound Tissue Characterization of the Transplanted Kidney
Authors: Sotomayor Camilo G. , Benjamens Stan , Dijkstra Hildebrand , Yakar Derya , Moers Cyril , Bakker Stephan J. L. , Pol Robert A.
Published: February 2021

Ultrasound examination is advised for early post-kidney transplant assessment. Grayscale median (GSM) quantification is novel in the kidney transplant field, with no systematic assessment previously reported. In this prospective cohort study, we measured the post-operative GSM in a large cohort of adult kidney transplant recipients (KTR) who consecutively underwent Doppler ultrasound directly after transplantation (within 24 h), compared it with GSM in nontransplanted patients, and investigated its association with baseline and follow-up characteristics. B-mode images were used to calculate the GSM in KTR and compared with GSM data in nontransplanted patients, as simulated from summary statistics of the literature using a Mersenne twister algorithm. The association of GSM with baseline and 1-year follow-up characteristics were studied by means of linear regression analyses. In 282 KTR (54 ± 15 years old, 60% male), the median (IQR) GSM was 55 (45–69), ranging from 22 to 124 (coefficient of variation = 7.4%), without differences by type of donation (p = 0.28). GSM in KTR was significantly higher than in nontransplanted patients (p < 0.001), and associated with systolic blood pressure, history of cardiovascular disease, and donor age (std. β = 0.12, −0.20, and 0.13, respectively; p < 0.05 for all). Higher early post-kidney transplant GSM was not associated with 1-year post-kidney transplant function parameters (e.g., measured and estimated glomerular filtration rate). The data provided in this study could be used as first step for further research on the application of early postoperative ultrasound in KTR.
Involvement of Oxidative Stress and the Innate Immune System in SARS-CoV-2 Infection
Authors: Kozlov Evgenii M. , Ivanova Ekaterina , Grechko Andrey V. , Wu Wei-Kai , Starodubova Antonina V. , Orekhov Alexander N.
Published: February 2021

The emergence of the novel coronavirus in December 2019 in China marked the beginning of a pandemic that impacted healthcare systems and economic life all over the world. The virus primarily targets the respiratory system causing severe acute respiratory syndrome (SARS) in some patients, and therefore received the name of SARS-CoV-2. The pathogen stands out among other coronaviruses by its rapid transmission from human to human, with the majority of infected individuals being asymptomatic or presenting with only minor illness, therefore facilitating the pathogen spread. At the same time, people from the risk groups, such as the elderly, patients suffering from chronic diseases, or obese individuals, have increased chances of developing a severe or even fatal disease. The search for risk factors explaining this phenomenon continues. In this review, we focus on the known mechanisms of SARS-CoV-2 infection affecting the functioning of the immune system and discuss potential risk factors responsible for the severe disease course. Oxidative stress is one of such factors, which plays a prominent role in innate immunity activity, and recent research has revealed its tight involvement in SARS-CoV-2 infection. We discuss these recent findings and the development of excessive inflammation and cytokine storm observed during SARS-CoV-2 infection. Finally, we consider potential use of antioxidant drugs for alleviating the severe symptoms in affected patients.
Safety Enhancement of UAVs from the Signal Processing’s Perspectives: A Bird’s Eye View
Authors: Kwan Chiman
Published: February 2021

Unmanned air vehicles (UAVs) or drones have gained popularity in recent years. However, the US Federal Aviation Administration (FAA) is still hesitant to open up the national air space (NAS) to UAVs due to safety concerns because UAVs have several orders of magnitude of more accidents than manned aircraft. To limit the scope in this paper, we focus on large, heavy, and expensive UAVs that can be used for cargo transfer and search and rescue operations, not small radio-controlled toy drones. We first present a general architecture for enhancing the safety of UAVs. We then illustrate how signal processing technologies can help enhance the safety of UAVs. In particular, we provide a bird’s eye view of the application of signal processing algorithms on condition-based maintenance, structural health monitoring, fault diagnostics, and fault mitigation, which all play critical roles in UAV safety. Some practical applications are used to illustrate the importance of the various algorithms.
Intermittency in Transitional Shear Flows
Authors: Duguet Yohann
Published: February 2021

The study of the transition from a laminar to a turbulent flow is as old as the study of turbulence itself [...]
Four-Objective Optimizations for an Improved Irreversible Closed Modified Simple Brayton Cycle
Authors: Tang Chenqi , Chen Lingen , Feng Huijun , Ge Yanlin
Published: February 2021

An improved irreversible closed modified simple Brayton cycle model with one isothermal heating process is established in this paper by using finite time thermodynamics. The heat reservoirs are variable-temperature ones. The irreversible losses in the compressor, turbine, and heat exchangers are considered. Firstly, the cycle performance is optimized by taking four performance indicators, including the dimensionless power output, thermal efficiency, dimensionless power density, and dimensionless ecological function, as the optimization objectives. The impacts of the irreversible losses on the optimization results are analyzed. The results indicate that four objective functions increase as the compressor and turbine efficiencies increase. The influences of the latter efficiency on the cycle performances are more significant than those of the former efficiency. Then, the NSGA-II algorithm is applied for multi-objective optimization, and three different decision methods are used to select the optimal solution from the Pareto frontier. The results show that the dimensionless power density and dimensionless ecological function compromise dimensionless power output and thermal efficiency. The corresponding deviation index of the Shannon Entropy method is equal to the corresponding deviation index of the maximum ecological function.
Study of Wound Healing Dynamics by Single Pseudo-Particle Tracking in Phase Contrast Images Acquired in Time-Lapse
Authors: Scheda Riccardo , Vitali Silvia , Giampieri Enrico , Pagnini Gianni , Zironi Isabella
Published: February 2021

Cellular contacts modify the way cells migrate in a cohesive group with respect to a free single cell. The resulting motion is persistent and correlated, with cells’ velocities self-aligning in time. The presence of a dense agglomerate of cells makes the application of single particle tracking techniques to define cells dynamics difficult, especially in the case of phase contrast images. Here, we propose an original pipeline for the analysis of phase contrast images of the wound healing scratch assay acquired in time-lapse, with the aim of extracting single particle trajectories describing the dynamics of the wound closure. In such an approach, the membrane of the cells at the border of the wound is taken as a unicum, i.e., the wound edge, and the dynamics is described by the stochastic motion of an ensemble of points on such a membrane, i.e., pseudo-particles. For each single frame, the pipeline of analysis includes: first, a texture classification for separating the background from the cells and for identifying the wound edge; second, the computation of the coordinates of the ensemble of pseudo-particles, chosen to be uniformly distributed along the length of the wound edge. We show the results of this method applied to a glioma cell line (T98G) performing a wound healing scratch assay without external stimuli. We discuss the efficiency of the method to assess cell motility and possible applications to other experimental layouts, such as single cell motion. The pipeline is developed in the Python language and is available upon request.
Increasing Requests for Information by Preschoolers with and without Language-Based Disabilities
Authors: Speckman JeanneMarie , Du Lin , Greer R. Douglas
Published: February 2021

We report two experiments on the emission of questions to request the names of unfamiliar stimuli by preschoolers. In the first experiment, 19 preschoolers with and without disabilities served as participants. Experiment 1 was a descriptive analysis of whether or not the 19 participants asked questions about unfamiliar pictures and objects in one-to-one and group settings. These were dependent variables in the second experiment as well. Four participants, who did not ask any questions in the first experiment, served as participants in the second experiment. During the intervention, the participants observed the peer confederates (1) ask questions (e.g., “What is that?”), (2) receive information from the experimenter, and (3) receive praise and tokens contingent on asking a question. A multiple probe design across participants was used. The data showed that the participants increased the number of questions when we returned to baseline conditions. Results are discussed in terms of where the reinforcement exists for asking questions about unfamiliar things in one’s environment, and whether this truly measures the “need to know”.
A Compact Modular 5 GW Pulse PFN-Marx Generator for Driving HPM Source
Authors: Zhang Haoran , Shu Ting , Liu Shifei , Zhang Zicheng , Song Lili , Zhang Heng
Published: February 2021

A compact and modular pulse forming network (PFN)-Marx generator with output parameters of 5 GW, 500 kV, and 30 Hz repetition is designed and constructed to produce intense electron beams for the purpose of high-power microwave (HPM) generation in the paper. The PFN-Marx is composed by 22 stages of PFN modules, and each module is formed by three mica capacitors (6 nF/50 kV) connected in parallel. Benefiting from the utilization of mica capacitors with high energy density and a mini-trigger source integrated into the magnetic transformer and the magnetic switch, the compactness of the PFN-Marx system is improved significantly. The structure of the PFN module, the gas switch unit, and the connection between PFN modules and switches are well designed for modular realization. Experimental results show that this generator can deliver electrical pulses with the pulse width of 100 ns and amplitude of 500 kV on a 59-ohm water load at a repetition rate of 30 Hz in burst mode. The PFN-Marx generator is fitted into a cuboid stainless steel case with the length of 80 cm. The ratio of storage energy to volume and the ratio of power to weight of the PFN-Marx generator are calculated to be 6.5 J/L and 90 MW/kg, respectively. Furthermore, utilizing the generator to drive the transit time oscillator (TTO) at a voltage level of 450 kV, a 100 MW microwave pulse with the pulse width of 20 ns is generated.
RSU-Aided Remote V2V Message Dissemination Employing Secure Group Association for UAV-Assisted VANETs
Authors: Tan Haowen , Chung Ilyong
Published: February 2021

Nowadays, the research on vehicular ad hoc networks (VANETs) remains a hot topic within the Internet of Things (IoT) scenarios. Diverse studies and techniques regarding all aspects of VANETs have been investigated thoroughly. Particularly, the wireless characteristic of heterogeneous vehicular communication, along with the complicated and dynamic connection topology among participating VANET entities, have severely affected the secure and stable data exchange. Specifically, the spontaneous vehicle-to-vehicle (V2V) message dissemination, as the essential functionality of VANET, plays a significant role for instant and real-time data sharing for vehicles within a certain vicinity. However, with the short-time interaction and high mobilization of vehicular connections, the remote V2V message delivery intended for long-distance vehicles in the range of different roadside units (RSUs) has not been properly researched. Meanwhile, both V2V and V2R (Vehicle-to-RSU) communication are highly restricted by environmental factors such as physical obstructions or signal interferences, thus drastically reducing the wireless connectivity in practical VANET implementations. In this case, the unmanned aerial vehicles (UAVs), as the auxiliary facilities, can provide the VANET with substitute wireless routes, so that the transmission quality and availability can be improved. In this paper, the authenticated UAV group association design is proposed at first. On this basis, the remote V2V message dissemination method is enabled, where the decentralized V2V connections involving all RSUs along the way are provided. The analysis regarding crucial security properties is presented accordingly, where the formal proofs and comparison are conducted. Moreover, the performance evaluation in terms of storage and time consumption during RSU authentication process is illustrated, respectively. Comparison results with the state-of-the-art prove that superiority on the major performance factors can be achieved.
Parametric Fault Diagnosis of Very High-Frequency Circuits Containing Distributed Parameter Transmission Lines
Authors: Tadeusiewicz Michał , Hałgas Stanisław
Published: February 2021

Parametric fault diagnosis of analog very high-frequency circuits consisting of a distributed parameter transmission line (DPTL) terminated at both ends by lumped one-ports is considered in this paper. The one-ports may include linear passive and active components. The DPTL is a uniform two-conductor line immersed in a homogenous medium, specified by the per-unit-length (p-u-l) parameters. The proposed method encompasses all aspects of parametric fault diagnosis: detection of the faulty area, location of the fault inside this area, and estimation of its value. It is assumed that only one fault can occur in the circuit. The diagnostic method is based on a measurement test arranged in the AC state. Different approaches are proposed depending on whether the faulty is DPTL or one of the one-ports. An iterative method is modified to solve various systems of nonlinear equations that arise in the course of the diagnostic process. The diagnostic method can be extended to a broader class of circuits containing several transmission lines. Three numerical examples reveal that the proposed diagnostic method is fast and gives quite accurate findings.
CO2 Utilization Technologies: A Techno-Economic Analysis for Synthetic Natural Gas Production
Authors: Szima Szabolcs , Cormos Calin-Cristian
Published: February 2021

Production of synthetic natural gas (SNG) offers an alternative way to valorize captured CO2 from energy intensive industrial processes or from a dedicated CO2 grid. This paper presents an energy-efficient way for synthetic natural gas production using captured CO2 and renewable hydrogen. Considering several renewable hydrogen production sources, a techno-economic analysis was performed to find a promising path toward its practical application. In the paper, the five possible renewable hydrogen sources (photo fermentation, dark fermentation, biomass gasification, bio photolysis, and PV electrolysis) were compared to the two reference cases (steam methane reforming and water electrolysis) from an economic stand point using key performance indicators. Possible hydrogen production capacities were also considered for the evaluation. From a technical point of view, the SNG process is an efficient process from both energy efficiency (about 57%) and CO2 conversion rate (99%). From the evaluated options, the photo-fermentation proved to be the most attractive with a levelized cost of synthetic natural gas of 18.62 €/GJ. Considering the production capacities, this option loses its advantageousness and biomass gasification becomes more attractive with a little higher levelized cost at 20.96 €/GJ. Both results present the option when no CO2 credit is considered. As presented, the CO2 credits significantly improve the key performance indicators, however, the SNG levelized cost is still higher than natural gas prices.
Modeling of German Low Voltage Cables with Ground Return Path
Authors: Geis-Schroer Johanna , Hubschneider Sebastian , Held Lukas , Gielnik Frederik , Armbruster Michael , Suriyah Michael , Leibfried Thomas
Published: February 2021

In this contribution, measurement data of phase, neutral, and ground currents from real low voltage (LV) feeders in Germany is presented and analyzed. The data obtained is used to review and evaluate common modeling approaches for LV systems. An alternative modeling approach for detailed cable and ground modeling, which allows for the consideration of typical German LV earthing conditions and asymmetrical cable design, is proposed. Further, analytical calculation methods for model parameters are described and compared to laboratory measurement results of real LV cables. The models are then evaluated in terms of parameter sensitivity and parameter relevance, focusing on the influence of conventionally performed simplifications, such as neglecting house junction cables, shunt admittances, or temperature dependencies. By comparing measurement data from a real LV feeder to simulation results, the proposed modeling approach is validated.
Modular Web Portal Approach for Stimulating Home Renovation: Lessons from Local Authority Developments
Authors: Kwon Minyoung , Mlecnik Erwin
Published: February 2021

Web portals have the potential to promote sustainable environmental ideas due to the capacity of digital media, such as easy accessibility, openness, and networking. Local authorities (LAs) are responsible for activating carbon savings in homes, and they are key actors when it comes to providing neutral information to their citizens. Local authority web portals may thus create environmental awareness, particularly regarding owner-occupied single-family home renovation. Nevertheless, the experiences of LAs developing web portals have rarely been studied. Therefore, this paper analyses the development process of various LA web modules and investigates how LAs foster modular web portals to stimulate the adoption of home renovation with parameters to assess LAs’ actions in terms of the management of web-modules development. A homeowner renovation journey model is applied to map current local authority developments. Case study research and interviews were done to analyse and evaluate the adoption of modular web portals developed and tested by six local authorities in four countries in Europe. Based on the development and use of the modular web portal, lessons have been derived emphasising the importance of co-creation, integrating with offline activities, and a strategic management plan.
On the Retrofit of Existing Buildings with Aerogel Panels: Energy, Environmental and Economic Issues
Authors: Marrone Paola , Asdrubali Francesco , Venanzi Daniela , Orsini Federico , Evangelisti Luca , Guattari Claudia , De Lieto Vollaro Roberto , Fontana Lucia , Grazieschi Gianluca , Matteucci Paolo , Roncone Marta
Published: February 2021

Among the super insulating materials, aerogel has interesting properties: very low thermal conductivity and density, resistance to high temperatures and transparency. It is a rather expensive material, but incentives in the field can improve its economic attractiveness. Starting from this, the thermal behavior of a test building entirely insulated with aerogel panels was investigated through an extended experimental campaign. A dynamic simulation model of a case study building was generated to better comprehend the energy savings obtained through aerogel in terms of energy demand over a whole year. The investigation was completed by computing the carbon and energy payback times of various retrofit strategies through a life cycle assessment approach, as well as by a cost-benefit analysis through a probabilistic financial framework. Compared to conventional insulation materials, aerogel is characterized by a higher energy and carbon payback time, but it guarantees better environmental performance in the whole life cycle. From an economic-financial perspective, the aerogel retrofit is the best in the current tax incentive scenario. However, due to its higher lump-sum investment, aerogel’s net present value is very sensitive to tax deductions, and it is riskier than the best comparable materials in less favorable tax scenarios.
Preparation, Functionalization, Modification, and Applications of Nanostructured Gold: A Critical Review
Authors: Yaseen Muhammad , Humayun Muhammad , Khan Abbas , Usman Muhammad , Ullah Habib , Tahir Asif Ali , Ullah Habib
Published: February 2021

Gold nanoparticles (Au NPs) play a significant role in science and technology because of their unique size, shape, properties and broad range of potential applications. This review focuses on the various approaches employed for the synthesis, modification and functionalization of nanostructured Au. The potential catalytic applications and their enhancement upon modification of Au nanostructures have also been discussed in detail. The present analysis also offers brief summaries of the major Au nanomaterials synthetic procedures, such as hydrothermal, solvothermal, sol-gel, direct oxidation, chemical vapor deposition, sonochemical deposition, electrochemical deposition, microwave and laser pyrolysis. Among the various strategies used for improving the catalytic performance of nanostructured Au, the modification and functionalization of nanostructured Au produced better results. Therefore, various synthesis, modification and functionalization methods employed for better catalytic outcomes of nanostructured Au have been summarized in this review.
Exergy Assessment and Thermo-Economic Analysis of Hybrid Solar Systems with Seasonal Storage and Heat Pump Coupling in the Social Housing Sector in Zaragoza
Authors: Martínez-Gracia Amaya , Usón Sergio , Pintanel Mª Teresa , Uche Javier , Bayod-Rújula Ángel A. , Del Amo Alejandro
Published: February 2021

A real case study of an energy system based on a Solar Assisted Heat Pump (SAHP) fed by hybrid photovoltaic-thermal solar panels (PVT) and seasonal storage (SS) is presented in this paper. Exergy and exergy cost analyses are proposed as complementary methods for the assessment and better understanding of the efficiency of this cogeneration solar configuration. The system performance takes advantage of storage heat in summer, when the solar resource is high in Spain, and is then later consumed during the cold winter (heating season). The building is devoted to social housing, and it is currently under construction. The assessment is based on simulations developed using TRNSYS, a dynamic simulation software for energy systems. Results show that the unit exergy cost of the solar field is around 6. The cost of the seasonal storage is higher, about 13, and its formation is affected both by its own irreversibility and by the irreversibility of the PVT solar field. The cost of the heat delivered by the heat pump is around 15, being affected by all the upstream units and even by the grid. Besides, the analysis points out strategies for improving the system efficiency, such as increasing the size of the storage tank or improving the control strategy of the boiler.
Multiple Solutions of the Tristable Energy Harvester
Authors: Litak Grzegorz , Margielewicz Jerzy , Gąska Damian , Wolszczak Piotr , Zhou Shengxi
Published: February 2021

This paper presents the results of numerical simulations of a non-linear, tristable system for harvesting energy from vibrating mechanical devices. Detailed model tests were carried out in relation to the system consisting of a beam and three permanent magnets. Based on the derived mathematical model and assuming a range of control parameter variability, a three-dimensional image of the distribution of the largest Lyapunov exponent was plotted. On its basis, the regions of chaotic and predictable movement of the considered system exist have been established. With reference to selected plane of the largest Lyapunov exponent cross-sections, possible co-existing solutions were identified. To identify multiple solutions, a diagram of solutions (DS) diagram was used to illustrate the number of existing solutions and their periodicity. The proposed calculation tool is based on the so-called fixed points of Poincaré cross-section. In relation to selected values of the control parameter ω, coexisting periodic solutions were identified for which phase trajectories and basins of attraction were presented. Based on the model tests carried out, it was found that in order to efficiently harvest energy, appropriate transducer adjustment is required. Calibration of the transducer is necessary to obtain the greatest amplitude of vibration of the beam, which corresponds to the phase trajectory limited by external energy potential barriers. As expected, the average voltage induced on the electrodes of the piezoelectric transducer and the average electrical power recorded on the resistive element are directly proportional to the amplitude and average kinetic energy of the beam.
Customer Privacy Concerns as a Barrier to Sharing Data about Energy Use in Smart Local Energy Systems: A Rapid Realist Review
Authors: Vigurs Carol , Maidment Chris , Fell Michael , Shipworth David
Published: February 2021

The purpose of this review is to investigate the nature of privacy concerns in the context of smart local energy systems (SLES) to understand how SLES providers can minimize both user concerns, and cause for concern, around privacy. We conducted a rapid realist review and thematic framework analysis against Bronfenbrenner’s socio–ecological model to understand privacy concerns in different contexts. A common privacy concern was that sharing detailed energy use data had the potential to reveal information about home life, and to intrude upon people’s sense of autonomy, choice, and control. Evidence suggests that people are willing to accept new data sharing technologies if the benefits of doing so are clear, anticipated, and mutually beneficial. Building trust, through increasing knowledge and understanding, was a mechanism for overcoming privacy concerns, but this was mediated by the organization providing the information. Non-profit organizations were more trusted to ensure appropriate safeguards to privacy were in place. One key barrier to participation with good supporting evidence was that people could resist perceived intrusions on their privacy. This could be actively resisted by refusing to install data collection technologies or passively by non-participation in adapting energy use behaviours: both of which are necessary for SLES to achieve their goals of managing energy demand and building resilience in smart grids.
Forecasting of 10-Second Power Demand of Highly Variable Loads for Microgrid Operation Control
Authors: Parol Mirosław , Piotrowski Paweł , Kapler Piotr , Piotrowski Mariusz
Published: February 2021

This paper addresses very short-term (10 s) forecasting of power demand of highly variable loads. The main purpose of this study is to develop methods useful for this type of forecast. We have completed a comprehensive study using two different time series, which are very difficult to access in practice, of 10 s power demand characterized by big dynamics of load changes. This is an emerging and promising forecasting research topic, yet to be more widely recognized in the forecasting research community. This problem is particularly important in microgrids, i.e., small energy micro-systems. Power demand forecasting, like forecasting of renewable power generation, is of key importance, especially in island mode operation of microgrids. This is due to the necessity of ensuring reliable power supplies to consumers. Inaccurate very short-term forecasts can cause improper operation of microgrids or increase costs/decrease profits in the electricity market. This paper presents a detailed statistical analysis of data for two sample low voltage loads characterized by large variability, which are located in a sewage treatment plant. The experience of the authors of this paper is that very short-term forecasting is very difficult for such loads. Special attention has been paid to different forecasting methods, which can be applied to this type of forecast, and to the selection of explanatory variables in these methods. Some of the ensemble models (eight selected models belonging to the following classes of methods: random forest regression, gradient boosted trees, weighted averaging ensemble, machine learning) proposed in the scope of choice of methods sets constituting the models set are unique models developed by the authors of this study. The obtained forecasts are presented and analyzed in detail. Moreover, qualitative analysis of the forecasts obtained has been carried out. We analyze various measures of forecasts quality. We think that some of the presented forecasting methods are promising for practical applications, i.e., for microgrid operation control, because of their accuracy and stability. The analysis of usefulness of various forecasting methods for two independent time series is an essential, very valuable element of the study carried out. Thanks to this, reliability of conclusions concerning the preferred methods has considerably increased.
Design, Analysis and Application of Single-Wheel Test Bench for All-Electric Antilock Braking System in Electric Vehicles
Authors: XUE Xiangdang , CHENG Ka Wai Eric , CHAN Wing Wa , FONG Yat Chi , KAN Kin Lung Jerry , FAN Yulong
Published: February 2021

An antilock braking system (ABS) is one of the most important components in a road vehicle, which provides active protection during braking, to prevent the wheels from locking-up and achieve handling stability and steerability. The all-electric ABS without any hydraulic components is a potential candidate for electric vehicles. To demonstrate and examine the all-electric ABS algorithms, this article proposes a single-wheel all-electric ABS test bench, which mainly includes the vehicle wheel, the roller, the flywheels, and the electromechanical brake. To simulate dynamic operation of a real vehicle’s wheel, the kinetic energy of the total rotary components in the bench is designed to match the quarter of the one of a commercial car. The vertical force to the wheel is adjustable. The tire-roller contact simulates the real tire-road contact. The roller’s circumferential velocity represents the longitudinal vehicle velocity. The design and analysis of the proposed bench are described in detail. For the developed prototype, the rated clamping force of the electromechanical brake is 11 kN, the maximum vertical force to the wheel reaches 300 kg, and the maximum roller (vehicle) velocity reaches 100 km/h. The measurable bandwidth of the wheel speed is 4 Hz–2 kHz and the motor speed is 2.5 Hz–50 kHz. The measured results including the roller (vehicle) velocity, the wheel velocity, and the wheel slip are satisfactory. This article offers the effective tools to verify all-electric ABS algorithms in a laboratory, hence saving time and cost for the subsequent test on a real road.