bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of the Bottom Color Modification and Material Color Modification Process on the Performance of Modified Poplar
Authors: Liu Qingqing , Gao Di , Xu Wei
Published: May 2021

According to the old surface coating process of European and American furniture, the surface of modified poplar is first differentiated pre-treatment, and then the bottom color modification and material color modification are respectively applied to the modified poplar after the surface differentiation treatment. The visual physical quantity and physical and chemical properties were measured and compared with mahogany, which is commonly used in old furniture in Europe and America to explore the effect of colorants and coloring steps, as well as different surface pretreatments on the coloring effect. Finally, it is concluded that continuous coloring operations can narrow the difference in brightness and red color value in the coloring layer of modified poplar and mahogany. Continuous coloring operations increase the difference between the yellow-green color values of modified poplar and mahogany. Therefore, the coloring difference between modified poplar and mahogany was affected by the colorant and coloring steps. Through color accumulation, the gap between the two in the target color coloring effect can be reduced, thereby reducing the difference between the coloring effect of modified poplar and mahogany.
Characterization of Macrophages and TNF-α in Cleft Affected Lip Tissue
Authors: Goida Jana , Pilmane Māra
Published: May 2021

Orofacial clefts are one of the most common congenital anomalies worldwide; however, morphopathogenesis of the clefts is not yet completely understood. Taking the importance of innate immunity into account, the aim of this work was to examine the appearance and distribution of macrophages (M) 1, M2, and TNF-α, as well as to deduce any possible intercorrelations between the three factors in cleft affected lip tissue samples. Twenty samples of soft tissue were collected from children during plastic surgery. Fourteen control tissue samples were obtained during labial frenectomy. Tissues were immunohistochemically stained, analysed by light microscopy using a semi-quantitative method, and the Mann–Whitney U and Spearman’s tests were used to evaluate statistical differences and correlations. A statistically significant difference in the distribution was observed only in regard to M1. A weak correlation was observed between M2 and TNF-α but a moderate one between M1 and M2 as well as M1 and TNF-α. However, only the correlation between M1 and M2 was statistically important. The rise in M1, alongside the positive correlation between M1 and TNF-α, suggested a more pro-inflammatory/inflammatory environment in the cleft affected lip tissue. The moderate positive correlation between M1 and M2 indicated an intensification of the protective mechanisms.
A Review of the Latest Developments in the Field of Refractory High-Entropy Alloys
Authors: Srikanth Muthe , Annamalai A. Raja , Muthuchamy A. , Jen Chun-Ping
Published: May 2021

This review paper provides insight into current developments in refractory high-entropy alloys (RHEAs) based on previous and currently available literature. High-temperature strength, high-temperature oxidation resistance, and corrosion resistance properties make RHEAs unique and stand out from other materials. RHEAs mainly contain refractory elements like W, Ta, Mo, Zr, Hf, V, and Nb (each in the 5–35 at% range), and some low melting elements like Al and Cr at less than 5 at%, which were already developed and in use for the past two decades. These alloys show promise in replacing Ni-based superalloys. In this paper, various manufacturing processes like casting, powder metallurgy, metal forming, thin-film, and coating, as well as the effect of different alloying elements on the microstructure, phase formation, mechanical properties and strengthening mechanism, oxidation resistance, and corrosion resistance, of RHEAs are reviewed.
Valorization of Powder Obtained from Marble Sludge Waste and Its Suitability as a Mineral Filler
Authors: Benjeddou Omrane , Alwetaishi Mamdooh
Published: May 2021

Stone industry has generated about 200 million tons of marble waste by marble processing industries whether in the form of sludge or solid blocks. The accumulated marble wastes contaminate water and air and have harmful effects on human health, plants, and animals. This study focuses on exploring the uses of powder obtained by drying and grinding marble sludge waste, generated from marble manufacturing processes, as a mineral filler for other construction materials. First, physical characterization was performed on marble sludge. Second, the powder preparation process was presented. Thereafter, a set of tests was carried out to identify the chemical, mineralogical, and physical properties of marble powder. By doing so, tests such as chemical analysis, calcium carbonate content, and methylene blue test, as well as mineralogical characterization using X-ray diffraction (XRD), Atterberg limits, particle size analysis, densities, Blaine specific surface, hydraulic property, as well as reaction with admixture, cement, and activity index were conducted. In the last part of this work, the obtained powder properties are compared to the standards requirements to confirm its suitability as mineral filler. The test results showed that the obtained marble powder is too rich in calcite; it is poor of any clay minerals fraction; it is very well graded; it is not reactive; and it does not have any effects on concrete strength; consequently, it can be considered as a mineral filler.
Summary of New Insight into Electron Transport in Metals
Authors: Palenskis Vilius , Žitkevičius Evaras
Published: May 2021

This paper gives a summary of a new insight into basic electron transport characteristics in crystalline elemental metals. The general expressions based on the Fermi-Dirac distribution of the effective density of the randomly moving electrons, their diffusion coefficient, drift mobility, and other characteristics, including the Einstein relation between diffusion coefficient and drift mobility, are presented. It is shown that the creation of the randomly moving electrons due to lattice atom vibrations produces the same number of electronic defects, which cause scattering of the randomly moving electrons and related transport characteristics.
Interventions and Outcomes for Neoadjuvant Treatment of T4 Colon Cancer: A Scoping Review
Authors: Jung Flora , Guidolin Keegan , Lee Michael , Lam-Tin-Cheung Kimberley , Zhao Grace , Doshi Sachin , Chesney Tyler , Englesakis Marina , Lukovic Jelena , O’Kane Grainne , Quereshy Fayez , Chadi Sami
Published: May 2021

While adjuvant treatment of colon cancers that penetrate the serosa (T4) have been well-established, neoadjuvant strategies have yet to be formally evaluated. Our objective was to perform a scoping review of eligibility criteria, treatment regimens, and primary outcomes for neoadjuvant approaches to T4 colon cancer. A librarian-led, systematic search of MEDLINE, Embase, Cochrane Library, Web of Science, and CINAHL up to 11 February 2020 was performed. Primary research evaluating neoadjuvant treatment in T4 colon cancer were included. Screening and data abstraction were performed in duplicate; analyses were descriptive or thematic. A total of twenty studies were included, most of which were single-arm, single-center, and retrospective. The primary objectives of the literature to date has been to evaluate treatment feasibility, tumor response, disease-free survival, and overall survival in healthy patients. Conventional XELOX and FOLFOX chemotherapy were the most commonly administered interventions. Rationale for selecting a specific regimen and for treatment eligibility criteria were poorly documented across studies. The current literature on neoadjuvant strategies for T4 colon cancer is overrepresented by single-center, retrospective studies that evaluate treatment feasibility and efficacy in healthy patients. Future studies should prioritize evaluating clear selection criteria and rationale for specific neoadjuvant strategies. Validation of outcomes in multi-center, randomized trials for XELOX and FOLFOX have the most to contribute to the growing evidence for this poorly managed disease.
Large-Scale Trade in a Songbird That Is Extinct in the Wild
Authors: Nijman Vincent , Campera Marco , Ardiansyah Ahmad , Balestri Michela , Bizri Hani R. El , Budiadi Budiadi , Dewi Tungga , Hedger Katherine , Hendrik Rifqi , Imron Muhammad Ali , Langgeng Abdullah , Morcatty Thais Q. , Weldon Ariana V. , Nekaris K. A. I.
Published: May 2021

Indonesia is at the epicenter of the Asian Songbird Crisis, i.e., the recognition that the cage bird trade has a devastating impact on numerous imperiled bird species in Asia. The Javan pied starling Gracupica jalla, only in the last five years recognized as distinct from the pied starlings of mainland Southeast Asia, has been declared extinct the wild in 2021. Up until the 1980s, it used to be one of the most common open countryside birds on the islands of Java and Bali, Indonesia. From the early 2000s onwards, the species is commercially bred to meet the demand from the domestic cagebird trade. We conducted 280 market surveys in 25 bird markets in Java and Bali between April 2014 and March 2020, with 15 markets being surveyed at least six times. We recorded 24,358 Javan pied starlings, making it one of the most commonly observed birds in the markets. We established that, conservatively, around 40% of the birds in the market were sold within one week and used this to estimate that at a minimum ~80,000 Javan pied starlings are sold in the bird markets on Java and Bali. The latter represents a monetary value of USD5.2 million. We showed that prices were low in the 1980s, when all birds were sourced from the wild. It became more varied and differentiated in the 2000s when a combination of now expensive wild-caught and cheaper captive-bred birds were offered for sale, and prices stabilized in the 2010s when most, if not all birds were commercially captive-bred. Javan pied starlings are not protected under Indonesian law, and there are no linked-up conservation efforts in place to re-establish a wild population on the islands, although small-scale releases do take place.
Polychaete Diversity Related to Different Mesophotic Bioconstructions along the Southeastern Italian Coast
Authors: Gravina Maria Flavia , Pierri Cataldo , Mercurio Maria , Nonnis Marzano Carlotta , Giangrande Adriana
Published: May 2021

In the different mesophotic bioconstructions recently found along the Southeastern Italian coast, polychaetes have been proved to show high species richness and diversity, hitherto never investigated. In the present study, the species composition and functional role of polychaete assemblages were analysed; the updated key to identification of the Mediterranean species of genus Eunice was presented and some taxonomic issues were also discussed. On the total of 70 species Serpulidae and Eunicida were the dominant polychaetes. Facing similar levels of α-diversity, the polychaete assemblages showed a high turnover of species along the north-south gradient, clearly according to the current circulation pattern, as well as to the different bioconstructors as biological determinants. Indeed, Serpulidae were dominant on the mesophotic bioconstructions primarily formed by the deep-sea oyster Neopycnodonte cochlear, while the Eunicida prevailed on the mesophotic bioconstructions mainly built by scleractinians. Lastly, the record of Eunice dubitata was the first for the Mediterranean and Italian fauna and proved this species to be characteristic of mesophotic bioconstructions.
Effects of Anti-Inflammatory Treatment and Surgical Intervention on Endothelial Glycocalyx, Peripheral and Coronary Microcirculatory Function and Myocardial Deformation in Inflammatory Bowel Disease Patients: A Two-Arms Two-Stage Clinical Trial
Authors: Triantafyllou Charilaos , Nikolaou Maria , Ikonomidis Ignatios , Bamias Giorgos , Kouretas Dimitrios , Andreadou Ioanna , Tsoumani Maria , Thymis John , Papaconstantinou Ioannis
Published: May 2021

Sixty inflammatory bowel disease (IBD) patients (45 Crohn disease and 15 ulcerative colitis, 40 ± 13 years, 53% male) were examined at baseline and 4 months after intervention (surgical (35 patients) or anti-TNFa treatment (25 patients)). IBD severity, using Mayo score, Harvey–Bradshaw Index (HBI) and biomarkers, was correlated with cardiovascular markers. At baseline, the disease severity, the white blood cells (WBC) values and the reducing power (RP) were significantly correlated with the aortic pulse wave velocity (PWV) (r = 0.4, r = 0.44 and r = 0.48, p < 0.05) and the lateral mitral E’ velocity (r = 0.35, p < 0.05 and r = 0.3, p < 0.05). Four months after intervention, there was a reduction of WBC (1962.8/mm3 ± 0.425/mm3, p < 0.001), C-reactive protein (CRP) (8.1 mg/L ± 1.7 mg/L, p < 0.001), malondialdehyde (MDA) (0.81 nmol/mg ± 0.37, p < 0.05) and glycocalyx perfused boundary region (PBR 5-25) (0.24 μm ± 0.05 μm, p < 0.01). Moreover, the brachial flow mediated dilatation (FMD), the coronary flow reserve (CFR) and the left ventricle global longitudinal strain (LV GLS) were significantly improved for both groups (4.5% ± 0.9%, 0.55 ± 0.08, 1.4% ± 0.35%, p < 0.01), while a more significant improvement of PWV/GLS was noticed in the anti-TNFa group. IBD severity is associated with vascular endothelial, cardiac diastolic, and coronary microcirculatory dysfunction. The systemic inflammatory inhibition and the local surgical intervention lead to significant improvement in endothelial function, coronary microcirculation and myocardial deformation.
Electromyographic Assessment of Anterior Cruciate Ligament Injury Risk in Male Tennis Players: Which Role for Visual Input? A Proof-of-Concept Study
Authors: de Sire Alessandro , Marotta Nicola , Demeco Andrea , Moggio Lucrezia , Paola Pasquale , Marotta Marcello , Iona Teresa , Invernizzi Marco , Leigheb Massimiliano , Ammendolia Antonio
Published: May 2021

Anterior cruciate ligament (ACL) injury incidence is often underestimated in tennis players, who are considered as subjects conventionally less prone to knee injuries. However, evaluation of the preactivation of knee stabilizer muscles by surface electromyography (sEMG) showed to be a predictive value in the assessment of the risk of ACL injury. Therefore, this proof-of-concept study aimed at evaluating the role of visual input on the thigh muscle preactivation through sEMG to reduce ACL injury risk in tennis players. We recruited male, adult, semiprofessional tennis players from July to August 2020. They were asked to drop with the dominant lower limb from a step, to evaluate—based on dynamic valgus stress—the preactivation time of the rectus femoris (RF), vastus medialis, biceps femoris, and medial hamstrings (MH), through sEMG. To highlight the influence of visual inputs, the athletes performed the test blindfolded and not blindfolded on both clay and grass surfaces. We included 20 semiprofessional male players, with a mean age 20.3 ± 4.8 years; results showed significant early muscle activation when the subject lacked visual input, but also when faced with a less-safe surface such as clay over grass. Considering the posteromedial–anterolateral relationship (MH/RF ratio), tennis players showed a significant higher MH/RF ratio if blindfolded (22.0 vs. 17.0% not blindfolded; p < 0.01) and percentage of falling on clay (17.0% vs. 14.0% in grass; p < 0.01). This proof-of-principle study suggests that in case of absence of visual input or falling on a surface considered unsafe (clay), neuro-activation would tend to protect the anterior stress of the knee. Thus, the sEMG might play a crucial role in planning adequate athletic preparation for semiprofessional male athletes in terms of reduction of ACL injury risk.
Cystic Fibrosis, New Frontier: Exploring the Functional Connectivity of the Brain Default Mode Network. Comment on Elce et al. Impact of Physical Activity on Cognitive Functions: A New Field for Research and Management of Cystic Fibrosis. Diagnostics 2020, 10, 489
Authors: Gambazza Simone , Nobili Rita Maria , Biffi Riccardo , Summers Paul Eugene , Colombo Carla , Costa Antonella
Published: May 2021

We read with great interest the paper entitled “Impact of physical activity of cognitive functions: a new field for research and management of Cystic Fibrosis” by Elce et al. [...]
Osteoconductivity of Bovine Xenograft Granules of Different Sizes in Sinus Lift: A Histomorphometric Study in Rabbits
Authors: Godoy Eduardo Pires , Apaza Alccayhuaman Karol Alí , Botticelli Daniele , Amaroli Andrea , Balan Vitor Ferreira , Silva Erick Ricardo , Xavier Samuel Porfirio
Published: May 2021

Background: Due to the lack of data on bone-to-graft contact (BGC) over time in the various regions within the subantral space of the augmented sinus floor, the present study aimed to evaluate the osteoconductivity of deproteinized bovine bone mineral (DBBM) with granules of different sizes applied in maxillary sinus floor elevation. Methods: A maxillary sinus augmentation was performed bilaterally in 18 rabbits using DBBM with particle dimensions of either 0.125–1.0 mm or 1–2 mm. The antrostomy was covered using a collagen barrier. The animals were euthanized in groups of six after 2, 4, and 8 weeks of healing. MicroCT and histological analyses were performed. Results: After 2 weeks of healing, BGC was 10.9% and 11.9% for the small and large granule sites, respectively. After 8 weeks of healing, the BGC increased to 65% and 62% at the small and large granule sites, respectively. The highest values were located close to the bony walls and the bony window. New bone content developed between 2 and 8 weeks from 7.0% to 27.6% and from 6.1% to 27.6% at the small and large granule sites, respectively. Conclusions: Similar outcomes in osteoconductivity and bone formation were found at both small and large DBBM granule sites.
Spectrum Slicing for Multiple Access Channels with Heterogeneous Services
Authors: Chiariotti Federico , Leyva-Mayorga Israel , Stefanović Čedomir , Kalør Anders E. , Popovski Petar
Published: May 2021

Wireless mobile networks from the fifth generation (5G) and beyond serve as platforms for flexible support of heterogeneous traffic types with diverse performance requirements. In particular, the broadband services aim for the traditional rate optimization, while the time-sensitive services aim for the optimization of latency and reliability, and some novel metrics such as Age of Information (AoI). In such settings, the key question is the one of spectrum slicing: how these services share the same chunk of available spectrum while meeting the heterogeneous requirements. In this work we investigated the two canonical frameworks for spectrum sharing, Orthogonal Multiple Access (OMA) and Non-Orthogonal Multiple Access (NOMA), in a simple, but insightful setup with a single time-slotted shared frequency channel, involving one broadband user, aiming to maximize throughput and using packet-level coding to protect its transmissions from noise and interference, and several intermittent users, aiming to either to improve their latency-reliability performance or to minimize their AoI. We analytically assessed the performances of Time Division Multiple Access (TDMA) and ALOHA-based schemes in both OMA and NOMA frameworks by deriving their Pareto regions and the corresponding optimal values of their parameters. Our results show that NOMA can outperform traditional OMA in latency-reliability oriented systems in most conditions, but OMA performs slightly better in age-oriented systems.
A Locally Both Leptokurtic and Fat-Tailed Distribution with Application in a Bayesian Stochastic Volatility Model
Authors: Lenart Łukasz , Pajor Anna , Kwiatkowski Łukasz
Published: May 2021

In the paper, we begin with introducing a novel scale mixture of normal distribution such that its leptokurticity and fat-tailedness are only local, with this “locality” being separately controlled by two censoring parameters. This new, locally leptokurtic and fat-tailed (LLFT) distribution makes a viable alternative for other, globally leptokurtic, fat-tailed and symmetric distributions, typically entertained in financial volatility modelling. Then, we incorporate the LLFT distribution into a basic stochastic volatility (SV) model to yield a flexible alternative for common heavy-tailed SV models. For the resulting LLFT-SV model, we develop a Bayesian statistical framework and effective MCMC methods to enable posterior sampling of the parameters and latent variables. Empirical results indicate the validity of the LLFT-SV specification for modelling both “non-standard” financial time series with repeating zero returns, as well as more “typical” data on the S&P 500 and DAX indices. For the former, the LLFT-SV model is also shown to markedly outperform a common, globally heavy-tailed, t-SV alternative in terms of density forecasting. Applications of the proposed distribution in more advanced SV models seem to be easily attainable.
Quantification of the Direct Solar Impact on Some Components of the Hydro-Climatic System
Authors: Mares Constantin , Mares Ileana , Dobrica Venera , Demetrescu Crisan
Published: May 2021

This study addresses the causal links between external factors and the main hydro-climatic variables by using a chain of methods to unravel the complexity of the direct sun–climate link. There is a gap in the literature on the description of a complete chain in addressing the structures of direct causal links of solar activity on terrestrial variables. This is why the present study uses the extensive facilities of the application of information theory in view of recent advances in different fields. Additionally, by other methods (e.g., neural networks) we first tested the existent non-linear links of solar–terrestrial influences on the hydro-climate system. The results related to the solar impact on terrestrial phenomena are promising, which is discriminant in the space-time domain. The implications prove robust for determining the causal measure of climate variables under direct solar impact, which makes it easier to consider solar activity in climate models by appropriate parametrizations. This study found that hydro-climatic variables are sensitive to solar impact only for certain frequencies (periods) and have a coherence with the Solar Flux only for some lags of the Solar Flux (in advance).
Semiparametric Estimation of a Corporate Bond Rating Model
Authors: Jiang Yixiao
Published: May 2021

This paper investigates the incentive of credit rating agencies (CRAs) to bias ratings using a semiparametric, ordered-response model. The proposed model explicitly takes conflicts of interest into account and allows the ratings to depend flexibly on risk attributes through a semiparametric index structure. Asymptotic normality for the estimator is derived after using several bias correction techniques. Using Moody’s rating data from 2001 to 2016, I found that firms related to Moody’s shareholders were more likely to receive better ratings. Such favorable treatments were more pronounced in investment grade bonds compared with high yield bonds, with the 2007–2009 financial crisis being an exception. Parametric models, such as the ordered-probit, failed to identify this heterogeneity of the rating bias across different bond categories.
Let Students Talk about Emergency Remote Teaching Experience: Secondary Students’ Perceptions on Their Experience during the COVID-19 Pandemic
Authors: Sofianidis Angelos , Meletiou-Mavrotheris Maria , Konstantinou Panagiota , Stylianidou Nayia , Katzis Konstantinos
Published: May 2021

This research aimed to comprehend the impact of the first school closure on secondary education in Cyprus from students’ perspectives. Through the administration of an online survey with both closed and open questions, the study investigated the main issues and challenges that students experienced during their abrupt transition from face-to-face to emergency remote education and their main worries and concerns during this period, as well as their perceptions regarding the effectiveness of the teaching and learning process followed during the distance education period. The study also elicited students’ suggestions, based on their experiences from the lockdown period, on improving instruction in case of further lockdown(s) and in the post-COVID-19 era. Three hundred twenty-two (322) students of both upper and lower secondary education participated in the study. The data from closed questions were analysed using descriptive and inferential statistics, and for the data from the open questions, a qualitative thematic analysis approach was followed. The valuable insights gained from this study illustrate how important it is for educators and educational policymakers to give voice to students, closely listen to what learners felt worked and what did not during the period of remote learning, and develop plans and policies that incorporate their feedback.
Power-Law Compensator Design for Plants with Uncertainties: Experimental Verification
Authors: Kapoulea Stavroula , Psychalinos Costas , Elwakil Ahmed S. , Tavazoei Mohammad Saleh
Published: May 2021

A power-law compensator scheme for achieving robust frequency compensation in control systems including plants with an uncertain pole, is introduced in this work. This is achieved through an appropriate selection of the compensator parameters, which guarantee that the Nyquist diagram of the open-loop system compensator-plant crosses a fixed point independent of the plant pole variations. The implementation of the fractional-order compensator is performed through the utilization of a curve-fitting-based technique and the derived rational integer-order transfer function is realized on a Field-Programmable Analog Array device. The experimental results confirm that the the phase margin is well preserved, even for ±40% variation in the pole location of the plant.
Multiple Sensor Fail-Operational Architecture for Electric Vehicle Powertrain Control System
Authors: Wang Yungchen , Chen Rongshun
Published: May 2021

With the expanding demand to meet specific safety requirements, a new definition of the architecture at the system level is required to keep the powertrain system still operational after the fault emerge of some sensors. This work proposes a fail-operational architecture by integrating battery management and motor control system, which implements heterogeneous sensor signal reconstruction and model-based signal estimation for redundant signal generation and adopts random forest for signal arbitration. The proposed architecture can reduce the system failure rate and allow a fault-toleration of up to three sensors at any given time without increasing costs. Finally, the proposed architecture was verified by comparing the fault detection performance among three arbitration algorithms in a model in the loop (MIL) platform.
A Novel Antenna for UHF RFID Near-Field Applications
Authors: Yao Yuan , Ge Qiuyue , Yu Junsheng , Chen Xiaodong
Published: May 2021

This paper proposed a novel antenna for ultra-high frequency (UHF) radio frequency identification (RFID) near-field applications with uniform distribution of the electric field along the x-axis (Ex), and the y-axis (Ey). The proposed antenna adopted a spiral structure to achieve broadband and multi-polarization. The novel antenna achieved good impedance matching within 860–960 MHz. Using a ground plate, the proposed antenna achieved low far-field gain and a maximum gain of less than −11 dBi. The component of the excited electric field Ex and Ey parallel to the antenna surface was uniformly distributed, and there was no zero point. The proposed antenna achieved a 100% read rate of tags parallel to its surface in the reading area of 150 mm × 150 mm × 220 mm. Simulation results were consistent with the results of real-world measurements, and the proposed antenna was suitable as a reader antenna in near-field applications. The polarization mode of RFID tags is mostly linear polarization, and the placement of tags in practical applications is diversified. Compared with the traditional RFID reader antenna, the proposed antenna achieves uniform electric field distribution parallel to the antenna surface, but the single-direction electric field has zero-reading points, which is easy to cause the misread of tags. The RFID tags can be read more accurately. To verify the scalability of the reading area of the spiral antenna unit, it was used for array design, and simulations were conducted using 1 × 2, 2 × 2, 1 × 4, and 2 × 4 arrays. The component distribution of the electric field excited by the four array antennas in the x and y directions was uniform and the reading area was controllable. Therefore, the proposed spiral antenna has the expandability of the reading area and can meet the needs of different application scenarios by changing the number of array units. With the array extension, the matching network also extends, and the impedance characteristics of the array antenna are somewhat different, but they also meet the application requirements.
An Intrinsically Switched Tunable CABW/CFBW Bandpass Filter
Authors: Du Tiejun , Guan Boran , Zhang Pengquan , Gu Yue , Wei Dujuan
Published: May 2021

In this paper, a novel intrinsically switched tunable bandpass filter based on a dual-mode T-shaped varactor-loaded resonator is presented. The varactors loaded in the T-shaped resonator are capable of efficiently tuning the resonant frequencies of the even and odd modes, as well as the transmission-zero frequency. Without any additional RF switches, the passband of the filter can be intrinsically switched off by adjusting the transmission zero to the resonant frequencies. In the switch-on state, the constant absolute bandwidth (CABW) or constant fractional bandwidth (CFBW) passband can be achieved by controlling the frequency space between the two resonances. For a demonstration, a 0.8–1.1 GHz intrinsically switched tunable bandpass filter with 74 MHz CABW or 8.5% CFBW was fabricated and tested. In the whole operating band with |S11| < 10 dB, the insertion losses for CABW and CFBW are better than 3.3 dB and 3 dB, respectively, and the isolations are better than 20 dB in the switch-off state. The measured results have a good agreement with simulated results, which verifies the design theory.
Segmentation of Food Consumers Based on Their Sustainable Attitude
Authors: Gazdecki Michał , Goryńska-Goldmann Elżbieta , Kiss Marietta , Szakály Zoltán
Published: May 2021

The proposed study aims to segment consumers based on a sustainable approach to the consumption of food. The shift in consumers’ attitudes towards more balanced food consumption can be one of the sustainability drivers for entire food chains and may result in more sustained energy usage in the whole food chain and implementation of farm to fork strategy to the practice. We considered consumers’ attitudes as a multidimensional construct. Under this assumption, we asked respondents a series of questions related to the cognitive, behavioral, and affective components of an attitude. Data were collected from a market survey run among 433 consumers. We identified three consumer segments. The “Doers” segment exhibits sustainable behavior to a greater extent than the others. At the same time, they have less knowledge about the concept of food sustainability while the affective dimension was developed on an average level. The “Conscious” segment had well-developed cognitive and affective dimensions (which might indicate their openness to the information about sustainability positive feelings), however, it was not reflected in their behavior. Finally, the “Reluctant” segment, did not show a sustainable attitude towards food consumption in any of the analyzed dimensions. Answering the question of how common sustainable attitudes are may help in determining the market potential and in developing product and promotion strategies.
Precise Evaluation of Gas–Liquid Two-Phase Flow Pattern in a Narrow Rectangular Channel with Stereology Method
Authors: Masiukiewicz Maciej , Anweiler Stanisław
Published: May 2021

The drive to increase the efficiency of processes based on two-phase flow demands the better precision and selection of boundary conditions in the process’ control. The two-phase flow pattern affects the phenomena of momentum, heat, and mass transfer. It becomes necessary to shift from its qualitative to quantitative evaluation. The description of the stationary structure has long been used in structural studies applied to metals and alloys. The description of a gas–liquid two-phase mixture is difficult because it changes in time and space. This paper presents a study of the precise determination of two-phase flow patterns based on stereological parameters analysis. The research area is shown against the flow map proposed by other researchers. The experiment was taken in the thin clear channel with dimensions of W = 50 × H = 1200 × T = 5 mm. The test method is based on the visualization of a two-phase air–water adiabatic flow pattern in the rectangular channel where superficial air velocities ranging from 0.006 to 0.044 m/s and the superficial water velocity ranged from 0.011 to 1.111 m/s. A high-speed camera was used for visualization. Images were analyzed with the use of stereological techniques. The study included the classification of structures according to generally accepted two-phase flow regime nomenclature for upwards co-current gas–liquid flow in a vertical rectangular channel. The result of the research was the determination of the stereological parameters’ changes with reference to the two-phase mixture flow hydrodynamics. The results were presented as waveform fluctuations in the values of stereological factors such as the volume fraction VV, interfacial surface SV, number of objects NV, mean chord l′m and the free distance λ. The description of how these parameters change with changes in phase fluxes is also presented. These waveforms help to distinguish the transient flow regimes, which allow for the automatic adjustment of the process stability. The authors found templates of the stereological parameters’ dependencies for flow pattern recognition. The research demonstrates wide possibilities of stereological methods’ application for the analysis of the two-phase gas–liquid process. The stereological model of two-phase pattern control enables the identification of process disorders.
Applying Wavelet Filters in Wind Forecasting Methods
Authors: Domínguez-Navarro José A. , Lopez-Garcia Tania B. , Valdivia-Bautista Sandra Minerva
Published: May 2021

Wind is a physical phenomenon with uncertainties in several temporal scales, in addition, measured wind time series have noise superimposed on them. These time series are the basis for forecasting methods. This paper studied the application of the wavelet transform to three forecasting methods, namely, stochastic, neural network, and fuzzy, and six wavelet families. Wind speed time series were first filtered to eliminate the high-frequency component using wavelet filters and then the different forecasting methods were applied to the filtered time series. All methods showed important improvements when the wavelet filter was applied. It is important to note that the application of the wavelet technique requires a deep study of the time series in order to select the appropriate family and filter level. The best results were obtained with an optimal filtering level and improper selection may significantly affect the accuracy of the results.
Factors for Bioeconomy Development in EU Countries with Different Overall Levels of Economic Development
Authors: Czyżewski Andrzej , Grzyb Andrzej , Matuszczak Anna , Michałowska Mariola
Published: May 2021

The aim of this article is to indicate the rationale for the development of the bioeconomy in selected EU countries depending on their overall level of economic development. The research was based on four highly developed countries, i.e., Germany, France, Finland and Denmark, and four medium-developed countries, i.e., Poland, Hungary, Czech Republic, and Slovakia for the period 2001–2018. Renewable energy consumption, biomass and agricultural production were analysed as determinants of the bioeconomy development. The question was also answered whether differences in terms of measures determining the level of bioeconomy development between countries with different levels of economic development during the studied period are decreasing or increasing, using sigma (σ)-convergence coefficients. It is shown that the development of the bioeconomy of the studied countries is related to their level of economic development. In the middle economically developed countries, real opportunities for the development of the bioeconomy are noted, through a high share of agriculture in national income; and in highly developed countries—high spending on research and development and the growth of eco-innovation, which contributes to maintaining a development advantage between these groups of countries.
Bi-Directional Power Flow in Switchgear with Static Transfer Switch Applied at Various Renewable Energies
Authors: Park Keon-Woo , Kim Chul-Hwan
Published: May 2021

In this study, we describe the development of a plug-in type of switchgear that can control bidirectional power flow. This switchgear system can connect distributed generations such as photovoltaic and wind turbine generation, and AC and DC loads. The proposed switchgear system consists of an inverter for connecting distributed generations and DC load, a static transfer switch (STS) that can control and interrupt the bidirectional power flow, and an intelligent electronic device (IED) that can control each facility using a communication system. Since the topology inside the switchgear is composed of DC bus, it can be operated as a plug-in type of system that can be used by simply connecting the converters of various distributed generations to the inverter in the developed switchgear system. In this study, we describe the overall structure of the proposed switchgear system and the operation of the components. In addition, prototypes of each facility are developed and the results of building a small testbed are presented. Finally, we verify the operation of the inverter by performing an experiment on the testbed and show that throughout a test sequence the proposed switchgear system works normally. The contributions of this study are the development of a plug-in type of switchgear for AC/DC and the actual test results presented through prototype development and testbed configuration.
Optimal Planning of Integrated Nuclear-Renewable Energy System for Marine Ships Using Artificial Intelligence Algorithm
Authors: Gabbar Hossam A. , Adham Md. Ibrahim , Abdussami Muhammad R.
Published: May 2021

Ocean-going ships are one of the primary sources of Greenhouse Gas (GHG) emissions. Several actions are being taken to reduce the GHG emissions from maritime vessels, and integration of Renewable Energy Sources (RESs) is one of them. Ocean-going marine ships need a large amount of reliable energy to support the propulsive load. Intermittency is one of the drawbacks of RESs, and penetration of RESs in maritime vessels is limited by the cargo carrying capacity and usable area of that ship. Other types of reliable energy sources need to be incorporated in ships to overcome these shortcomings of RESs. Some researchers proposed to integrate fossil fuel-based generators like diesel generators and renewable energy in marine vessels to reduce GHG emissions. As the penetration of RESs in marine ships is limited, fossil fuel-based generators provide most of the energy. Therefore, renewable and fossil fuel-based hybrid energy systems in maritime vessels can not reduce GHG emissions to the desired level. Fossil fuel-based generators need to be replaced by emissions-free energy sources to make marine ships free from emissions. Nuclear energy is emissions-free energy, and small-scale nuclear reactors like Microreactors (MRs) are competent to replace fossil fuel-based generators. In this paper, the technical, environmental, and economic competitiveness of Nuclear-Renewable Hybrid Energy Systems (N-R HES) in marine ships are assessed. The lifecycle cost of MR, reliability of the proposed system, and limitations of integrating renewable energy in maritime vessels are considered in this study. The proposed N-R HES is compared with three different energy systems, namely ‘Standalone Fossil Fuel-based Energy Systems’, ‘Renewable and Fossil Fuel-based Hybrid Energy Systems’, and ‘Standalone Nuclear Energy System’. The cost modeling of each energy system is carried out in MATLAB simulator. Each energy system is optimized by using the Differential Evolution Algorithm (DEA), an artificial intelligence algorithm, to find out the optimal configuration of the system components in terms of Net Present Cost (NPC). The results determine that N-R HES has the lowest NPC compared to the other three energy systems. The performance of the DE algorithm is compared with another widely accepted artificial intelligence optimization technique called ‘Particle Swarm Optimization (PSO)’ to validate the findings of the DE algorithm. The impact of control parameters in the DE algorithm is assessed by employing the Adaptive Differential Evolution (ADE) algorithm. A sensitivity analysis is carried out to assess the impact of different system parameters on this study’s findings.
Electrical Modelling and Mismatch Effects of Thermoelectric Modules on Performance of a Thermoelectric Generator for Energy Recovery in Diesel Exhaust Systems
Authors: Ezzitouni Samir , Fernández-Yáñez Pablo , Sánchez Rodríguez Luis , Armas Octavio , de las Morenas Javier , Massaguer Eduard , Massaguer Albert
Published: May 2021

Thermoelectric generators harvesting energy from exhaust gases usually present a temperature mismatch between modules, due to the gradual cooling of the gases along the flow direction. The way modules that produce unequal voltages are connected has a deep impact on the overall power output. A further step in the prediction of thermoelectric production is to consider the complete layout of the thermoelectric modules and not consider them as isolated systems. In this work, a model to predict the electric behavior of thermoelectric generators for automotive applications at different points of operation is presented. The model allows testing of serial-parallel connection configurations. The results present good agreement with experimental data. This model could be used on similar light duty vehicles with similar engines as the engine used in this work and using similar configuration of thermoelectric generators. Simulated scenarios considering realistic operating conditions in a light duty vehicle allow stating that thermoelectric modules interconnection under heterogenous thermal surface conditions has a significant negative effect (more than 17%) on electric energy production. Moreover, the proposed model shows the need to protect the electric circuit of the thermoelectric generator to avoid the negative effect of possible malfunction of some thermoelectric modules.
Synchronization of N-Non-Linear Slave Systems with Master System Using Non-Adaptive and Adaptive Coupled Observers
Authors: Hussain Ghayyur , Siddique Muhammad , Hussain Muhammad Majid , Hassan Muhammad Tahir , Aslam Naeem
Published: May 2021

Synchronization of N-slave chaotic systems with a master system is a challenging task, particularly in recent times. In this paper, a novel methodology is proposed for synchronizing the N number of slave systems with a master system. The proposed methodology is based on coupled adaptive synchronous observers. The difference between the corresponding states of master and slave systems is converged to the origin by means of a novel feedback control scheme to achieve synchronization between the master and slave systems. The efficacy of the proposed methodology is verified through a simulation of FitzHugh–Nagumo non-linear systems in MATLAB. The simulation results validate and prove claims, and these systems are successfully synchronized by CCS and CCAS observer-based control.
A Novel Real-Time Electricity Scheduling for Home Energy Management System Using the Internet of Energy
Authors: Alhasnawi Bilal Naji , Jasim Basil H. , Siano Pierluigi , Guerrero Josep M.
Published: May 2021

This paper presents a novel scheduling scheme for the real-time home energy management systems based on Internet of Energy (IoE). The scheme is a multi-agent method that considers two chief purposes including user satisfaction and energy consumption cost. The scheme is designed under environment of microgrid. The user impact in terms of energy cost savings is generally significant in terms of system efficiency. That is why domestic users are involved in the management of domestic appliances. The optimization algorithms are based on an improved version of the rainfall algorithm and the salp swarm algorithm. In this paper, the Time of Use (ToU) model is proposed to define the rates for shoulder-peak and on-peak hours. A two-level communication system connects the microgrid system, implemented in MATLAB, to the cloud server. The local communication level utilizes IP/TCP and MQTT and is used as a protocol for the global communication level. The scheduling controller proposed in this study succeeded the energy saving of 25.3% by using the salp swarm algorithm and saving of 31.335% by using the rainfall algorithm.
Towards the Hydrogen Economy—A Review of the Parameters That Influence the Efficiency of Alkaline Water Electrolyzers
Authors: Santos Ana L. , Cebola Maria-João , Santos Diogo M. F.
Published: May 2021

Environmental issues make the quest for better and cleaner energy sources a priority. Worldwide, researchers and companies are continuously working on this matter, taking one of two approaches: either finding new energy sources or improving the efficiency of existing ones. Hydrogen is a well-known energy carrier due to its high energy content, but a somewhat elusive one for being a gas with low molecular weight. This review examines the current electrolysis processes for obtaining hydrogen, with an emphasis on alkaline water electrolysis. This process is far from being new, but research shows that there is still plenty of room for improvement. The efficiency of an electrolyzer mainly relates to the overpotential and resistances in the cell. This work shows that the path to better electrolyzer efficiency is through the optimization of the cell components and operating conditions. Following a brief introduction to the thermodynamics and kinetics of water electrolysis, the most recent developments on several parameters (e.g., electrocatalysts, electrolyte composition, separator, interelectrode distance) are highlighted.