bluuebunny/crossref_metadata_2025 huggingface dataset:
The Parameters Comparison of the “Starlink” LEO Satellites Constellation for Different Orbital Shells
Authors: Cakaj Shkelzen
Published: May 2021

Communications-integrated satellite-terrestrial networks used for global broadband services have gained a high degree of interest from scientists and industries worldwide. The most convenient structures for such use are low Earth orbit satellites, since they fly closer to the Earth compared to the other orbits, and consequently provide significantly lower latency, which is essential for reliable and safe communications. Among these efforts is the Starlink satellites constellation, developed and partly deployed by the United States Company SpaceX. The constellation is planned to be organized in three spatial shells, each of them made up of several hundreds of small-dimensioned and light-weighted low Earth orbit specially designed satellites to provide broadband services, intending to offer global Earth coverage through their interoperability, combined also with the ground stations as a part of the satellite-terrestrial integrated network. By October 24, 2020, 893 satellites are situated in orbit of altitudes of 550 km under different inclinations, determining the first Starlink orbital shell. Two next generations are planned to be situated at altitudes of 1,110 and 340 km, to complete the appropriate infrastructure of three Starlink satellite shells, toward a global presence of broadband internet services. These three orbital shells offer different space views seen from the ground station (user) because of their different altitudes, thus in this paper a few parameters which describe the satellite’s behavior considered from the ground station’s (user’s) point of view are compared. These parameters in fact stem from the space orbital parameters and are defined as: horizon plane wideness, slant range, latency, and coverage area. A comparison is given for the three Starlink orbit layers, with identification of appropriate drawbacks and advantages as performance indicators. By the end, these parameters are applied to geometrically interpret and confirm the handover process among satellites. This paper may serve to highlight the new challenges of the satellite-terrestrial integrated network, providing some theoretical analysis and performance comparisons for the satellites in different orbit layers seen from the ground station (user) perspective.
A Global MetaUniversity to Lead by Design to a Sustainable Well-Being Future
Authors: Costanza Robert , Kubiszewski Ida , Kompas Tom , Sutton Paul C.
Published: May 2021

The COVID19 pandemic has revealed deep, ingrained problems with higher education, but also opportunities for positive transformation. In the post-COVID world, education at all levels has the chance to become: (1) universally available at low cost; (2) focused on developing competencies, (3) empowering fulfilling lives, not merely job training; and (4) engaged with communities to solve real-world problems. Achieving this will require overcoming the mass production model of higher education by utilizing the full potential of the Internet in creative ways balanced with face-to-face solutions-based integrated learning, research, and outreach agenda. Building a global collaborative consortium of universities and other educational institutions can move this agenda forward. We describe how this “MetaUniversity” could be structured and how it would serve to advance this agenda and lead the way to a sustainable well-being future for humanity and the rest of nature.
“I Like the Way You Move”: Validating the Use of Point-Light Display Animations in Virtual Reality as a Methodology for Manipulating Levels of Sexualization in the Study of Sexual Objectification
Authors: Nolet Kévin , Viel Alexandre , Bouchard Stéphane
Published: May 2021

Sexual objectification of others has seen a growing research interest in recent years. While promising, the field lacks standardized stimuli, resulting in a confusion between sexualization and sexual objectification, which limits the interpretability of published results. In this study, we propose to use point-light display (PLD) as a novel methodology for manipulating sexualization levels as a first step toward isolating movement from other visual cues (e.g., clothing or physical appearance) for studying effects of sexual objectification of others. To do so, we first developed 8 virtual reality animations varying on 3 dimensions: 1) nature of movement (dance vs. walk), 2) level of sexualization (low vs. high), and 3) animation speed (slow and fast). Then, we validated these stimuli with perception ratings from 211 participants via an online survey. Using mixed linear regression models, we found evidence that our manipulation was successful: while participants took longer, were less accurate, and less confident in their response when confronted with a dancing, sexualized PLD, they also rated it as significantly more sexualized. This latter effect was stronger for participants perceiving a woman dancing compared to participants who perceived other genders. Overall, participants who reported more frequent sexual objectification behaviors also perceived the animations as more sexualized. Taken together, these results suggest that sexual suggestiveness can be manipulated by rather simple movement cues, thus validating the use of PLD as a stepping stone to systematically study processes of sexual objectification. From there, it is now possible to manipulate other variables more precisely during immersions in virtual reality, whether by adding a skin to the animated skeleton, by situating the PLD into different context, by varying the amplitude and the nature of the movements, or by modifying the context of the virtual environment.
The Invisible Threat: How Microplastics Endanger Corals
Authors: Bednarz Vanessa , Leal Miguel , Béraud Eric , Ferreira Marques Joana , Ferrier-Pagès Christine
Published: May 2021

Coral reefs are one of the most endangered habitats due to climate change, but not enough attention has been paid to how plastic pollution affects coral reef health. Plastics are massively produced worldwide for many purposes and they degrade very slowly, breaking down into tiny, invisible particles of 5 mm or less, called microplastics. When these tiny particles reach coral reefs, they harm corals by constantly rubbing on them through the action of waves and currents. Corals may also ingest microplastics and get a false sense of “fullness,” which results in the coral not feeding on nutritious food. Within the coral, microplastics may block the gut and cause internal damage. Also, microplastics, which are already made of chemicals, can pick up pollutants and harmful microorganisms from the seawater and transfer them to the coral. A reduction of microplastics pollution is therefore urgent.
Birthing Between the “Traditional” and the “Modern”: DāĪ Practices and Childbearing Women’s Choices During COVID-19 in Pakistan
Authors: Ali Inayat , Sadique Salma , Ali Shahbaz , Davis-Floyd Robbie
Published: May 2021

Pregnancy and birth are biological phenomena that carry heavy cultural overlays, and pregnant and birthing women need care and attention during both ordinary and extraordinary times. Most Pakistani pregnant women now go to doctors and hospitals for their perinatal care. Yet traditional community midwives, calledDāĪin the singular andDāyūnin the plural, still attend 24% of all Pakistani births, primarily in rural areas. In this article,viadata collected from 16 interviews—5 with Dāyūn and 11 with mothers, we explore a maternity care system in tension between the past and the present, the DāĪ and the doctor. We ask, what does the maternity care provided by the Dāyūn look like during times of normalcy, and how does it differ during COVID-19? We look at the roles the DāĪ has traditionally performed and how these roles have been changing, both in ordinary and in Covidian circumstances. Presenting the words of the Dāyūn we interviewed, all from Pakistan’s Sindh Province, we demonstrate their practices and show that these have not changed during this present pandemic, as these Dāyūn,like many others in Sindh Province, do not believe that COVID-19 is real—or are at least suspect that it is not. To contextualize the Dāyūn, we also briefly present local mother’s perceptions of the Dāyūn in their regions, which vary between extremely positive and extremely negative. Employing the theoretical frameworks of “authoritative knowledge” and of critical medical anthropology, we highlight the dominance of “modern” biomedicine over “traditional” healthcare systems and its effects on the Dāyūn and their roles within their communities. Positioning this article within Pakistan’s national profile, we propose formally training and institutionalizing the Dāyūn in order to alleviate the overwhelming burdens that pandemics—present and future—place on this country’s fragile maternity care system, to give mothers more—and more viable—options atalltimes, and to counterbalance the rising tide of biomedical hegemony over pregnancy and birth.
The Physical Activity and Sport Participation Framework—A Policy Model Toward Being Physically Active Across the Lifespan
Authors: Westerbeek Hans , Eime Rochelle
Published: May 2021

The changing social and policy context in which sport is produced, delivered, and consumed is considered as a foundation for proposing a new integrated framework that incorporates participation in sport with participation in leisure-time physical activity (PA) more broadly. In order to position sport in the broader context of leisure-time PA, the concept of physical literacy is reviewed and integrated into the theoretical foundations of a new lifespan framework. It is argued that historically, sport policy largely focused on competitive club-based sport and elite performance and that in line with this, talent development pathway models were developed and implemented. However, with increasing physical inactivity globally, these models do not apply to the general population. This is why we propose a population-based “whole of sport ecosystem” lifespan model—the Physical Activity and Sport Participation (PASP) framework. We conclude that this framework may serve as a holistic policy and implementation guide for all in the sport ecosystem. This includes governmental PA and sport policy makers, sport governing bodies and clubs, and the ever-increasing range of private PA and sport providers and also health agencies. In recognition of the changing patterns of participation in PA and sport across the lifespan, the PASP framework can contribute to coordinated and integrated PA and sport policy development, which, in turn, can lead to strategies that tackle the global physical inactivity crisis.
Functional and in silico Characterization of Neutralizing Interactions Between Antibodies and the Foot-and-Mouth Disease Virus Immunodominant Antigenic Site
Authors: Marrero Diaz de Villegas Ruben , Seki Cristina , Mattion Nora M. , König Guido A.
Published: May 2021

Molecular knowledge of virus–antibody interactions is essential for the development of better vaccines and for a timely assessment of the spread and severity of epidemics. For foot-and-mouth disease virus (FMDV) research, in particular, computational methods for antigen–antibody (Ag–Ab) interaction, and cross-antigenicity characterization and prediction are critical to design engineered vaccines with robust, long-lasting, and wider response against different strains. We integrated existing structural modeling and prediction algorithms to study the surface properties of FMDV Ags and Abs and their interaction. First, we explored four modeling and two Ag–Ab docking methods and implemented a computational pipeline based on a reference Ag–Ab structure for FMDV of serotype C, to be used as a source protocol for the study of unknown interaction pairs of Ag–Ab. Next, we obtained the variable region sequence of two monoclonal IgM and IgG antibodies that recognize and neutralize antigenic site A (AgSA) epitopes from South America serotype A FMDV and developed two peptide ELISAs for their fine epitope mapping. Then, we applied the previous Ag–Ab molecular structure modeling and docking protocol further scored by functional peptide ELISA data. This work highlights a possible different behavior in the immune response of IgG and IgM Ab isotypes. The present method yielded reliable Ab models with differential paratopes and Ag interaction topologies in concordance with their isotype classes. Moreover, it demonstrates the applicability of computational prediction techniques to the interaction phenomena between the FMDV immunodominant AgSA and Abs, and points out their potential utility as a metric for virus-related, massive Ab repertoire analysis or as a starting point for recombinant vaccine design.
Global Comprehensive Literature Review and Meta-Analysis of Brucella spp. in Swine Based on Publications From 2000 to 2020
Authors: Gong Qing-Long , Sun Yu-Han , Yang Yang , Zhao Bo , Wang Qi , Li Jian-Ming , Ge Gui-Yang , Chen Zi-Yang , Shi Kun , Leng Xue , Zong Ying , Du Rui
Published: May 2021

Background:Brucellosis, a zoonotic disease, infects various hosts, including swine and humans. It has reemerged in recent years as a public health concern, and current studies on brucellosis infection in swine have been conducted worldwide. However, no meta-analyses of global brucellosis infection in swine have been published. The aim of this study was to provide an overview ofBrucellaspecies (spp.) in swine worldwide and the factors associated with its persistence.

Results:We searched seven databases for published epidemiological studies on brucellosis in pigs, including the Chinese National Knowledge Infrastructure, Wanfang Data, SpringerLink, ScienceDirect, Web of Science, the VIP Chinese Journal Database and PubMed. We selected 119 articles published from January 1, 2000 to January 3, 2020 for inclusion in the meta-analysis and analyzed the data using a random-effects model. Funnel plots and Egger's test showed significant publication bias in the included studies. The results of the sensitivity analysis showed that our study was relatively stable and reliable. The prevalence of brucellosis in swine was 2.1% (95% CI: 1.6–2.6), of which the highest infection rate, which was found in Europe, was 17.4% (95% CI: 11.1–24.9). The prevalence in feral pigs (15.0%, 95% CI: 8.4–23.2) was higher than that in domestic pigs (1.1%, 95% CI 0.2–2.5). The prevalence in high-income countries (15.7%, 95% CI 8.0–25.3) was significantly higher than that in middle- (0.8%, 95% CI 0.5–1.1), and low-income countries (0.1%, 95% CI 0.0–0.2). The prevalence was highest in finishing pigs at 4.9% (95% CI 0.9–11.0), and lowest among suckling pigs at 0% (95% CI 0.0–0.5).

Conclusion:TheBrucellaprevalence in pig herds currently is distributed widely throughout the world. In some countries, swine brucellosis may be a neglected zoonotic disease. We recommend long-term monitoring of the prevalence of brucellosis in domestic and wild pig herds. Attention should also be paid to animal welfare on intensive pig farms; controlling the breeding density may play an important role in reducing the spread of brucellosis among pigs.
Rein Tension Signals Elicit Different Behavioral Responses When Comparing Bitted Bridle and Halter
Authors: Eisersiö Marie , Byström Anna , Yngvesson Jenny , Baragli Paolo , Lanata Antonio , Egenvall Agneta
Published: May 2021

When a rider maintains contact on the reins, rein tension will vary continuously in synchronicity with the horse's gait and stride. This continuous variation makes it difficult to isolate the rein tension variations that represent a rein tension signal, complicating interpretation of rein tension data from the perspective of horse-rider interaction. This study investigated (1) the characteristics of a rein tension signal and (2) horse response to a rein tension signal for backing, comparing pressure applied by a bit (bridle), or by a noseband (halter). Twenty Warmblood horses (10 young, 10 adult) wearing a rein tension meter were trained to step back in the aisle of a stable. The handler stood next to the horse's withers, applying tension on the reins until the horse stepped back. This was repeated eight times with the bridle and eight times with the halter. Data analysis was performed using mixed linear and logistic regression models. Horses displaying behaviors other than backing showed significantly increased response latency and rein tension. Inattentive behavior was significantly more common in the halter treatment and in young horses, compared with the bridle treatment and adult horses. Evasive behaviors with the head, neck, and mouth were significantly more common in the bridle treatment than in the halter treatment and the occurrence of head/neck/mouth behaviors increased with increasing rein tension and duration of the rein tension signal. When controlling for behavior, the horses responded significantly faster and to a lighter rein tension signal in the bridle treatment than in the halter treatment. By scrutinizing data on rein tension signals in relation to horse behavior and training exercise, more can be learnt about the horse's experience of the pressures applied and the timing of the release. This can assist in developing ways to evaluate rein tension in relation to correct use of negative reinforcement.
An Approach for Rice Bacterial Leaf Streak Disease Segmentation and Disease Severity Estimation
Authors: Chen Shuo , Zhang Kefei , Zhao Yindi , Sun Yaqin , Ban Wei , Chen Yu , Zhuang Huifu , Zhang Xuewei , Liu Jinxiang , Yang Tao
Published: May 2021

Rice bacterial leaf streak (BLS) is a serious disease in rice leaves and can seriously affect the quality and quantity of rice growth. Automatic estimation of disease severity is a crucial requirement in agricultural production. To address this, a new method (termed BLSNet) was proposed for rice and BLS leaf lesion recognition and segmentation based on a UNet network in semantic segmentation. An attention mechanism and multi-scale extraction integration were used in BLSNet to improve the accuracy of lesion segmentation. We compared the performance of the proposed network with that of DeepLabv3+ and UNet as benchmark models used in semantic segmentation. It was found that the proposed BLSNet model demonstrated higher segmentation and class accuracy. A preliminary investigation of BLS disease severity estimation was carried out based on our BLS segmentation results, and it was found that the proposed BLSNet method has strong potential to be a reliable automatic estimator of BLS disease severity.
Estimating Causal Effects When the Treatment Affects All Subjects Simultaneously: An Application
Authors: Binelli Chiara
Published: May 2021

Several important questions cannot be answered with the standard toolkit of causal inference since all subjects are treated for a given period and thus there is no control group. One example of this type of questions is the impact of carbon dioxide emissions on global warming. In this paper, we address this question using a machine learning method, which allows estimating causal impacts in settings when a randomized experiment is not feasible. We discuss the conditions under which this method can identify a causal impact, and we find that carbon dioxide emissions are responsible for an increase in average global temperature of about 0.3 degrees Celsius between 1961 and 2011. We offer two main contributions. First, we provide one additional application of Machine Learning to answer causal questions of policy relevance. Second, by applying a methodology that relies on few directly testable assumptions and is easy to replicate, we provide robust evidence of the man-made nature of global warming, which could reduce incentives to turn to biased sources of information that fuels climate change skepticism.
Metronomic Chemotherapy Modulates Clonal Interactions to Prevent Drug Resistance in Non-Small Cell Lung Cancer
Authors: Bondarenko Maryna , Le Grand Marion , Shaked Yuval , Raviv Ziv , Chapuisat Guillemette , Carrère Cécile , Montero Marie-Pierre , Rossi Mailys , Pasquier Eddy , Carré Manon , André Nicolas
Published: May 2021

Despite recent advances in deciphering cancer drug resistance mechanisms, relapse is a widely observed phenomenon in advanced cancers, mainly due to intratumor clonal heterogeneity. How tumor clones progress and impact each other remains elusive. In this study, we developed 2D and 3D non-small cell lung cancer co-culture systems and defined a phenomenological mathematical model to better understand clone dynamics. Our results demonstrated that the drug-sensitive clones inhibit the proliferation of the drug-resistant ones under untreated conditions. Model predictions and their experimental in vitro and in vivo validations indicated that a metronomic schedule leads to a better regulation of tumor cell heterogeneity over time than a maximum-tolerated dose schedule, while achieving control of tumor progression. We finally showed that drug-sensitive and -resistant clones exhibited different metabolic statuses that could be involved in controlling the intratumor heterogeneity dynamics. Our data suggested that the glycolytic activity of drug-sensitive clones could play a major role in inhibiting the drug-resistant clone proliferation. Altogether, these computational and experimental approaches provide foundations for using metronomic therapy to control drug-sensitive and -resistant clone balance and highlight the potential of targeting cell metabolism to manage intratumor heterogeneity.
ΔNp73, TAp73 and Δ133p53 Extracellular Vesicle Cargo as Early Diagnosis Markers in Colorectal Cancer
Authors: Rodríguez-Cobos Javier , Viñal David , Poves Carmen , Fernández-Aceñero María J. , Peinado Héctor , Pastor-Morate Daniel , Prieto Mª Isabel , Barderas Rodrigo , Rodríguez-Salas Nuria , Domínguez Gemma
Published: May 2021

The early diagnosis of colorectal cancer is a key factor in the overall survival of the patients. The actual screening programs include different approaches with significant limitations such as unspecificity, high invasiveness, and detection at late stages of the disease. The specific content of extracellular vesicles derived from malignant cells may represent a non-invasive technique for the early detection of colorectal cancer. Here, we studied the mRNA levels of ΔNp73, TAp73, and Δ133p53 in plasma-derived extracellular vesicles from healthy subjects (n = 29), individuals with premalignant lesions (n = 49), and colorectal cancer patients (n = 42). Extracellular vesicles’ ΔNp73 levels were already significantly high in subjects with premalignant lesions. Δ133p53 levels were statistically increased in colorectal cancer patients compared to the other two groups and were associated with patients’ survival. Remarkably, TAp73 mRNA was not detected in any of the individuals. The evaluation of ΔNp73, Δ133p53 and CEA sensitivity, specificity and AUC values supports ΔNp73 as a better early diagnosis biomarker and CEA as the best to identify advanced stages. Thus, low levels of CEA and a high content of ΔNp73 may identify in screening programs those individuals at higher risk of presenting a premalignant lesion. In addition, Δ133p53 emerges as a potential prognosis biomarker in colorectal cancer.
In Vitro and In Vivo Cell Uptake of a Cell-Penetrating Peptide Conjugated with Fluorescent Dyes Having Different Chemical Properties
Authors: Takakura Hideo , Sato Honoka , Nakajima Kohei , Suzuki Motofumi , Ogawa Mikako
Published: May 2021

In molecular imaging, a targeting strategy with ligands is widely used because specificity can be significantly improved. In fluorescence imaging based on a targeting strategy, the fluorescent dyes conjugated with ligands may affect the targeting efficiency depending on the chemical properties. Herein, we used a cell-penetrating peptide (CPP) as a ligand with a variety of fluorescent cyanine dye. We investigated in vitro and in vivo cell uptake of the dye-CPP conjugates when cyanine dyes with differing charge and hydrophilicity/lipophilicity were used. The results showed that the conjugates with positively charged and lipophilic cyanine dyes accumulated in cancer cells in vitro, but there was almost no accumulation in tumors in vivo. On the other hand, the conjugates with negatively charged and hydrophilic cyanine dyes did not accumulate in cancer cells in vitro, but fluorescence was observed in tumors in vivo. These results show that there are some cases in which the cell uptake of the dye-peptide conjugates may differ significantly between in vitro and in vivo experiments due to the chemical properties of the fluorescent dyes. This suggests that attention should be paid to the chemical properties of fluorescent dyes in fluorescence imaging based on a targeting strategy.
Microstructure and Corrosion Properties of Laser Cladding Fe-Based Alloy Coating on 27SiMn Steel Surface
Authors: Ouyang Changyao , Bai Qiaofeng , Yan Xianguo , Chen Zhi , Han Binhui , Liu Yan
Published: May 2021

In this paper, the corrosion performance of a laser cladding Fe-based alloy coating on the surface of 27SiMn steel was studied. The Fe-based alloy coating was prepared on a 27SiMn steel surface by high-speed laser cladding. The microstructure, morphological characteristics, element content, and phase composition of the cladding layer were analyzed by an optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), and X-ray diffractometer (XRD), respectively. The corrosion resistance of the 27SiMn substrate and Fe-based coating in different corrosive environments was tested through an electrochemical experimental station, a salt spray corrosion test box, and an immersion experiment. The Fe-based alloy cladding layer is mainly composed of a-Fe, M7C3, M2B, and Cr3Si. The cladding layer structure forms planar, cellular, dendrite, and equiaxed dendrite during rapid solidification. The corrosion potential of the cladding layer is higher than that of the substrate, and the arc radius of the cladding layer is larger than that of the substrate. After salt spray corrosion, a large number of red and black corrosion products appeared on the surface of the substrate; the surface of the cladding layer sample was still smooth, and the morphology was almost unchanged. The weight loss results of the cladding layer and 27SiMn matrix after 120 h of immersion are 0.0688 and 0.0993 g·cm−2, respectively. The weight loss of the cladding layer is 30.7% less than that of the matrix. Conclusion: Laser cladding an Fe-based alloy coating on the surface of 27SiMn has better corrosion resistance than the substrate, which improves the corrosion resistance of hydraulic supports.
Bio-Mediated Soil Improvement Using Plant Derived Enzyme in Addition to Magnesium Ion
Authors: Imran Md Al , Nakashima Kazunori , Kawasaki Satoru
Published: May 2021

Recently, soil improvement using EICP (Enzyme-Induced Carbonate Precipitation) methods in the geotechnical and geo-environmental field has become a prominent interest worldwide. The objective of this study was to develop an improved extraction technique of crude urease from watermelon seeds in both dry and germinated conditions. Subsequently, this study also analyzed the improvement methodology of crystal polymorphs and soil bonding incorporation of various Mg2+/Ca2+ ratios. The optimization of enzyme-mediated carbonate precipitation was also investigated by Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) analysis. Results confirmed that the precipitated crystals are mainly calcite, vaterite and aragonite primarily (depending on the Mg2+/Ca2+ ratios). Therefore, to improve the bonding capacity in between the sand particles a novel improvement methodology was investigated by adding various Mg2+/Ca2+ ratios. The mechanical properties of the treated soil (Mikawa Sand, D50 = 0.870 mm) specimens were tested by unconfined compressive strength (UCS) and this confirmed the effectiveness of adding various Mg2+/Ca2+ ratios. The results of the UCS tests showed that, the lower molar ratios of Mg2+/Ca2+ can significantly improve the UCS of the specimen (up to 50%) which could be considered a significant outcome for different bio-geotechnical applications.
A Review on Metamaterials for Device Applications
Authors: Suresh Kumar N. , Naidu K. Chandra Babu , Banerjee Prasun , Anil Babu T. , Venkata Shiva Reddy B.
Published: May 2021

Metamaterials are the major type of artificially engineered materials which exhibit naturally unobtainable properties according to how their microarchitectures are engineered. Owing to their unique and controllable effective properties, including electric permittivity and magnetic permeability, the metamaterials play a vital role in the development of meta-devices. Therefore, the recent research has mainly focused on shifting towards achieving tunable, switchable, nonlinear, and sensing functionalities. In this review, we summarize the recent progress in terahertz, microwave electromagnetic, and photonic metamaterials, and their applications. The review also encompasses the role of metamaterials in the advancement of microwave sensors, photonic devices, antennas, energy harvesting, and superconducting quantum interference devices (SQUIDs).
Visual Secure Image Encryption Scheme Based on Compressed Sensing and Regional Energy
Authors: Shi Mengna , Guo Shiyu , Song Xiaomeng , Zhou Yanqi , Wang Erfu
Published: May 2021

The network security transmission of digital images needs to solve the dual security problems of content and appearance. In this paper, a visually secure image compression and encryption scheme is proposed by combining compressed sensing (CS) and regional energy. The plain image is compressed and encrypted into a secret image by CS and zigzag confusion. Then, according to the regional energy, the secret image is embedded into a carrier image to obtain the final visual secure cipher image. A method of hour hand printing (HHP) scrambling is proposed to increase the pixel irrelevance. Regional energy embedding reduce the damage to the visual quality of carrier image, and the different embedding positions between images greatly enhances the security of the encryption algorithm. Furthermore, the hyperchaotic multi-character system (MCS) is utilized to construct measurement matrix and control pixels. Simulation results and security analyses demonstrate the effectiveness, security and robustness of the propose algorithm.
Novel Five-Level ANPC Bidirectional Converter for Power Quality Enhancement during G2V/V2G Operation of Cascaded EV Charger
Authors: Lara Jorge , Masisi Lesedi , Hernandez Concepcion , Arjona Marco A. , Chandra Ambrish
Published: May 2021

This paper presents a novel single-phase (SP) active-neutral point clamped (ANPC) five-level bidirectional converter (FLBC) for enhancing the power quality (PQ) during the grid-to-vehicle (G2V) and vehicle-to-grid (V2G) operation of an electric vehicle (EV) charger connected in series. This EV charger is based on a dual-active half-bridge DC-DC converter (DAHBC) with a high frequency isolation transformer. Unlike the comparable ANPC topologies found in literature, the proposed one has two more switches, i.e., ten instead of eight. However, with the addition of these components, the proposed multilevel converter not only becomes capable of properly balancing the voltage of the DC-link split capacitors under various step-changing conditions but it achieves a better efficiency, a lower stress of the switching devices and a more even distribution of the power losses. The resulting grid-tied ANPC-SPFLBC and DAHBC are accurately controlled with a cascaded control strategy and a single-phase shift (SPS) control technique, respectively. The simulation results obtained with MATLAB-SimPowerSystems as well as the experimental results obtained in laboratory validate the proposed ANPC-SPFLBC for a set of exhaustive tests in both V2G and G2V modes. A detailed power quality analysis carried out with a Fluke 43B alike demonstrates the good performance of the proposed topology.
External Costs for Agriculture from Lignite Extraction from the Złoczew Deposit
Authors: Pepliński Benedykt
Published: May 2021

In many circles, including in Poland, lignite is still viewed as a cheap source of energy, which is only possible if the external costs associated with mining and burning coal are not taken into account. In Poland, this is reflected in plans to open new Złoczew opencast lignite mines. In previous studies, the analysis of external costs has focused on the external costs of coal combustion and related pollutant emissions. This paper focuses on the extraction phase. The aim of the work here described was to estimate the external costs that agriculture may incur due to the formation of a depression funnel for the projected lignite mine in the Złoczew deposit. This paper discusses factors causing uncertainty in calculated estimates of external costs in agriculture, and characterizes the Bełchatów and Złoczew opencast mines. In the paper, a methodology for calculating external costs in livestock production is then proposed. In the next part of the study, the decrease in cereal and potato yields and in the number of cattle and pigs in the area of the cone of depression of the Bełchatów opencast mine, which has been in operation for 40 years, were estimated. The estimates obtained formed the basis for estimating external costs for the planned Złoczew lignite opencast. The analyses showed high external costs for plant production and much lower for animal production. The inclusion of the estimated external costs of 12.2 € × kWh−1 in the costs of electricity production will significantly worsen the profitability of launching this opencast. The paper discusses factors causing uncertainty in calculated estimates of external costs in agriculture, and characterizes the Bełchatów and Złoczew opencast mines. The discussion also shows that the level of losses incurred in crop production due to opencast coal mining is similar to the losses incurred in crop production in extremely dry years.
Analysis of Daily Load Patterns Taking into Consideration PEVs Charging Stations in Seoul, South Korea
Authors: Choi Sangbong , Kim Changsoo , Sung Backsub
Published: May 2021

This paper presents a methodology to calculate daily charging load curves in Seoul, South Korea, by taking into account plug-in electric vehicles (PEVs) charging stations, allowing Seoul’s government to determine the PEVs charging effect on the load. In particular, the study calculates the charging power of uncontrolled PEVs charging in terms of the daily operating characteristics of a vehicle traveling between home and workplace, with respect to PEVs charging stations in the city, according to the PEVs’ market share. For the controlled PEVs charging strategy based on morning and afternoon work-to-home and vice versa traffic characteristics and time-of-use (TOU) prices in Seoul, the study calculates daily load patterns of uncontrolled and controlled charging scenarios. After adding the calculated values to the existing load, the study assesses and compares their effects on the power grid. The results are as follows. If by 2030 the share of electric vehicles is 10%, compared to the existing load, the total load increases by about 13% between 9:00 and 11:00 in the morning for the uncontrolled mode and by about 10% for the controlled mode. The total load increases by about 16% between 20:00 and 22:00 for the uncontrolled mode and 17% for the controlled mode. However, if by 2040 the share of electric vehicles is 30%, compared to the existing load, the total load increases by about 35% between 9:00 and 11:00 in the morning for the uncontrolled mode and by about 32% for the controlled mode. Between 20:00 and 22:00, the uncontrolled mode’s total charging load increases by about 35% and the controlled mode’s total load by about 32%. The analysis also demonstrated that it was possible to achieve a significant load-leveling effect in all charging periods for the controlled mode, with the daily load pattern’s average leveling rate increasing by 8% and 13% in 2030 and 2040, respectively, based on the TOU price system compared with the uncontrolled mode. Based on these results, it is possible to determine the PEVs’ hourly charging load effect on the power grid in Seoul and establish a PEVs charging load management plan to prevent the power grid reinforcement and expansion and to satisfy its overload constraint by using an appropriate TOU price plan.
One-Pot Synthesis of Bismuth Sulfide Nanostructures as an Active Electrode Material for Aqueous Hybrid Capacitors
Authors: Moyseowicz Adam , Moyseowicz Agata
Published: May 2021

The high theoretical capacity of Bi2S3 shows high promise as a negative electrode material for energy storage devices. Herein, we investigate a facile, one-step chemical precipitation method using common organic solvents, such as acetone, ethanol, and isopropanol, for the synthesis of Bi2S3 nanostructures. The nanospherical Bi2S3 from acetone (Bi2S3-A) presents the most balanced electrochemical properties, exhibiting a high specific capacity of 181 mAh g−1 at 1 A g−1 and decent rate capability. Additionally, Bi2S3-A is used as a negative electrode in an aqueous hybrid system with an activated carbon positive electrode, demonstrating a capacitance of 86 F g−1, a specific energy of 7.6 Wh kg−1, and an initial capacity retention of 74% after 1000 cycles.
The Economic Performance of Hydropower Dams Supported by the World Bank Group, 1975–2015
Authors: Baurzhan Saule , Jenkins Glenn P. , Olasehinde-Williams Godwin O.
Published: May 2021

This paper assesses the economic benefits of 57 World Bank Group-sponsored hydropower dam plant investments. Hydropower dams are among the main sources for producing electricity and the largest renewable source for power generation throughout the world. Hydropower dams are often a lower-cost option for power generation in Clean Energy Transition for addressing global climate change. Despite its conspicuous aspects, constructing hydropower dams has been controversial. Considering the World Bank’s long history as the largest hydropower development financier, this study investigates its performance in supporting hydropower dams. The outcomes of this study apply to the wider hydropower development community. Of the projects in this study, 70% experienced a cost overrun, and more than 80% of projects experienced time overruns, incurring potential additional costs as a result. Despite the high cost and time overruns, this hydropower portfolio of dams produced a present value of net economic benefits by 2016 of over half a trillion USD. Based on our findings, the evaluated hydropower portfolio helped avoid over a billion tonnes of CO2 for an estimated global environmental benefit valued at nearly USD 350 billion. The projects’ additional environmental benefits raise the real rate of return from 15.4% to 17.3%. The implication for hydropower developers is that the projects’ assessment should consider cost and time overrun and factor them into the project-planning contingency scenarios. There is a considerable benefit for developing countries to exploit their hydropower resources if they can be developed according to industry practices and international standards. The case for developing hydropower may be stronger when considering its climate benefits. The net economic benefits of hydropower can be even higher if there is a greater effort to manage cost and time overruns.
Analyzing Characteristics of Particulate Matter Pollution in Open-Pit Coal Mines: Implications for Green Mining
Authors: Luo Huaiting , Zhou Wei , Jiskani Izhar Mithal , Wang Zhiming
Published: May 2021

The particulate pollution in the open-pit coal mines of China is particularly severe in winter. The aim of this study is to understand the pollution characteristics of particulate matter (PM) in winter and provide a basis for the prevention and control of particulate pollution. We took the problem of PM concentration at the bottom of the Haerwusu Open-pit Coal Mine (HOCM) as the research object. Dust monitoring equipment at two measurement points at different heights were positioned for continuous monitoring of the PM concentration. The data for three months were gathered. Statistical analyses were performed to analyze the variation characteristics of the PM and its relationship with meteorological factors. The results show that the average PM concentration in the study area is below the average daily limit of the China National Ambient Air Quality Standard (GB 3095-2012). However, the average concentration of PM10 exceeded the national limit in December. The order of PM concentration is observed as December > January > February. The correlation of PM is found to be positive with humidity and negative with wind speed. Temperature is found to be positively correlated with PM in December, while it is negative in January. At the same time, the temperature difference in December is negatively correlated with PM concentration. Under the combined action of multiple meteorological factors, the magnitude of the impact on the PM concentration at the bottom of the pit in winter is humidity > temperature > wind speed > temperature difference (inverse temperature intensity). In conclusion, PM2.5 is found to be more sensitive to environmental factors. The results of this study are particularly useful to progress in green mining.
Connection System for Small and Medium-Size Wind Generators through the Integration in an MMC and NLC Modulation
Authors: Martinez-Rodrigo Fernando , Ramirez Dionisio , de Pablo Santiago , Herrero-de Lucas Luis Carlos
Published: May 2021

This paper presents a new way of organizing a wind farm with a large number of small to medium-sized turbines. Each wind generator has been included in a switching module of a modular multilevel converter (MMC), which generates the output voltage by near level control (NLC). The proposed topology reduces the number of semiconductors required, switching losses, and voltage filtering requirements. This topology replaces the usual configuration where each wind turbine is connected to a three-phase two-level back-to-back converter plus a filter and then connected in parallel with the other wind generators. To test the topology and its control performance, a case has been developed and simulated for generator configurations producing the same power, for generation imbalances between phases and for imbalances between arms. The analysis of the data shows that the converter works correctly and that it can deliver power to the grid in a balanced way even if the generation has imbalances. The generation imbalances between phases are compensated through the average value of the circulating current, while the imbalances between arms are compensated through the 50 Hz circulating current.
Drag Reduction in the Flow of Aqueous Solutions of a Mixture of Cocamidopropyl Betaine and Cocamide DEA
Authors: Różański Jacek , Różańska Sylwia , Mitkowski Piotr Tomasz , Szaferski Waldemar , Wagner Patrycja , Frankiewicz Adrianna
Published: May 2021

The study presents results of rheological tests and measurements of pressure drops occurring during the flow of aqueous solutions of a mixture of drag reducing surfactants: cocamidopropyl betaine (CAPB, zwitterionic surfactant) and cocamide DEA (nonionic surfactant) through straight pipes. Tests were carried out at different CAPB/DEA weight ratios and different total concentrations of surfactants in the solution. Rheological measurements demonstrate the formation of a shear-induced structure (SIS) in the temperature range below 10 °C, which provides evidence for the presence of wormlike micelles in CAPB/DEA solutions. Drag reduction was observed during the flow of CAPB/DEA solutions in the temperature range from 3 to 45 °C, however, above 25 °C the degree of drag reduction was markedly decreased. The lower temperature limit at which drag reduction occurs depends on the CAPB and DEA weight ratio in the solution. In the range of higher temperatures, during the flow of CAPB/DEA solutions (similarly to flexible-chain polymer solutions) the onset of drag reduction is noted above a certain critical value of the Rec,0 number, whose value depends on the temperature of the solution, diameter of the pipe and the weight ratio of surfactants. At the same time, the critical value of wall shear stress τw,c0 corresponding to the critical value of Rec,0 is approximately independent of pipe diameter. The critical value of the Rec,0 number has been linked to the clouding of CAPB/DEA solutions.
Using Heat Pumps to Improve the Efficiency of Combined-Cycle Gas Turbines
Authors: Sergeev Vitaly , Anikina Irina , Kalmykov Konstantin
Published: May 2021

This paper studies the integration of heat pump units (HPUs) to enhance the thermal efficiency of a combined heat and power plant (CHPP). Different solutions of integrate the HPUs in a combined-cycle gas turbine (CCGT) plant, the CCGT-450, are analyzed based on simulations developed on “United Cycle” computer-aided design (CAD) system. The HPUs are used to explore low-potential heat sources (LPHSs) and heat make-up and return network water. The use of HPUs to regulate the gas turbine (GT) intake air temperature during the summer operation and the possibility of using a HPU to heat the GT intake air and replace anti-icing system (AIS), over the winter at high humidity conditions were also analyzed. The best solution was obtained for the winter operation mode replacing the AIS by a HPU. The simulation results indicated that this scheme can reduce the underproduction of electricity generation by the CCGT unit up to 14.87% and enhance the overall efficiency from 40.00% to 44.82%. Using a HPU with a 5.04 MW capacity can save $309,640 per each MW per quarter.
Review of Impedance-Based Analysis Methods Applied to Grid-Forming Inverters in Inverter-Dominated Grids
Authors: Ray Ishita
Published: May 2021

As the use of distributed generation with power electronics-based interfaces increases, the separation between DC and AC parts of the grid is reduced. In such inverter-dominated AC grids, impedance-based analysis methods are proving to be more powerful than traditional state-space-based analysis methods. Even the conventional parameters and standards used to estimate the stability of generators and stronger grids cannot fully capture the dynamics of weaker, inverter-dominated grids. It then stands to reason that system impedances that are commonly used to analyze DC systems will be useful in the analysis of grid-forming inverters in these hybrid systems. To understand the value of studying the impedances of inverters and other elements in weak AC grids, this article reviews and describes the various ways in which impedance-based analyses can be used to define, assess, and improve the performance of grid-forming inverter controllers. An exemplary case using the conventional P-f/Q-V droop control demonstrates the application of impedance-based analyses to determine the impact of the controller on the input and output stability of the inverter.