bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of Poly(methacrylic acid-co-butyl acrylate) Grafted onto Functionalized Carbon Nanotube Nanocomposites for Drug Delivery
Authors: Torres-Ávalos Josué A. , Cajero-Zul Leonardo R. , Vázquez-Lepe Milton , López-Dellamary Fernando A. , Martínez-Richa Antonio , Barrera-Rivera Karla A. , López-Serrano Francisco , Nuño-Donlucas Sergio M.
Published: February 2021

Design of a smart drug delivery system is a topic of current interest. Under this perspective, polymer nanocomposites (PNs) of butyl acrylate (BA), methacrylic acid (MAA), and functionalized carbon nanotubes (CNTsf) were synthesized by in situ emulsion polymerization (IEP). Carbon nanotubes were synthesized by chemical vapor deposition (CVD) and purified with steam. Purified CNTs were analyzed by FE-SEM and HR-TEM. CNTsf contain acyl chloride groups attached to their surface. Purified and functionalized CNTs were studied by FT-IR and Raman spectroscopies. The synthesized nanocomposites were studied by XPS, 13C-NMR, and DSC. Anhydride groups link CNTsf to MAA–BA polymeric chains. The potentiality of the prepared nanocomposites, and of their pure polymer matrices to deliver hydrocortisone, was evaluated in vitro by UV–VIS spectroscopy. The relationship between the chemical structure of the synthesized nanocomposites, or their pure polymeric matrices, and their ability to release hydrocortisone was studied by FT-IR spectroscopy. The hydrocortisone release profile of some of the studied nanocomposites is driven by a change in the inter-associated to self-associated hydrogen bonds balance. The CNTsf used to prepare the studied nanocomposites act as hydrocortisone reservoirs.
Polymer Processing and Surfaces
Authors: Sedlačík Michal
Published: February 2021

Polymer processing and surfaces are considered key parameters for developing unique materials for various applications [...]
The Thermal Behavior of Lyocell Fibers Containing Bis(trimethylsilyl)acetylene
Authors: Makarov Igor , Vinogradov Markel , Mironova Maria , Shandryuk Georgy , Golubev Yaroslav , Berkovich Anna
Published: February 2021

This study focuses on the preparation of carbon fiber precursors from solutions of cellulose in N-methylmorpholine-N-oxide with the addition of bis(trimethylsilyl)acetylene, studying their structural features and evaluating thermal behavior. The introduction of a silicon-containing additive into cellulose leads to an increase in the carbon yield during carbonization of composite precursors. The type of the observed peaks on the differential scanning calorimetry (DSC) curves cardinally changes from endo peaks intrinsic for cellulose fibers to the combination of endo and exo peaks for composite fibers. For the first time, coefficient of thermal expansion (CTE) values were obtained for Lyocell fibers and composite fibers with bis(trimethylsilyl)acetylene (BTMSA). The study of the dependence of linear dimensions of the heat treatment fibers on temperature made it possible to determine the relation between thermal expansion coefficients of carbonized fibers and thermogravimetric curves, as well as to reveal the relationship between fiber shrinkage and BTMSA bis(trimethylsilyl)acetylene content. Carbon fibers from composite precursors are obtained at a processing temperature of 1200 °C. A study of the structure of carbon fibers by X-ray diffraction, Raman spectroscopy, and transmission electron microscopy made it possible to determine the amorphous structure of the fibers obtained.
Fire-Safe Polymer Composites: Flame-Retardant Effect of Nanofillers
Authors: Kim Yukyung , Lee Sanghyuck , Yoon Hyeonseok
Published: February 2021

Currently, polymers are competing with metals and ceramics to realize various material characteristics, including mechanical and electrical properties. However, most polymers consist of organic matter, making them vulnerable to flames and high-temperature conditions. In addition, the combustion of polymers consisting of different types of organic matter results in various gaseous hazards. Therefore, to minimize the fire damage, there has been a significant demand for developing polymers that are fire resistant or flame retardant. From this viewpoint, it is crucial to design and synthesize thermally stable polymers that are less likely to decompose into combustible gaseous species under high-temperature conditions. Flame retardants can also be introduced to further reinforce the fire performance of polymers. In this review, the combustion process of organic matter, types of flame retardants, and common flammability testing methods are reviewed. Furthermore, the latest research trends in the use of versatile nanofillers to enhance the fire performance of polymeric materials are discussed with an emphasis on their underlying action, advantages, and disadvantages.
Interface and Interphase in Polymer Nanocomposites with Bare and Core-Shell Gold Nanoparticles
Authors: Power Albert J. , Remediakis Ioannis N. , Harmandaris Vagelis
Published: February 2021

Metal nanoparticles are used to modify/enhance the properties of a polymer matrix for a broad range of applications in bio-nanotechnology. Here, we study the properties of polymer/gold nanoparticle (NP) nanocomposites through atomistic molecular dynamics, MD, simulations. We probe the structural, conformational and dynamical properties of polymer chains at the vicinity of a gold (Au) NP and a functionalized (core/shell) Au NP, and compare them against the behavior of bulk polyethylene (PE). The bare Au NPs were constructed via a systematic methodology starting from ab-initio calculations and an atomistic Wulff construction algorithm resulting in the crystal shape with the minimum surface energy. For the functionalized NPs the interactions between gold atoms and chemically adsorbed functional groups change their shape. As a model polymer matrix we consider polyethylene of different molecular lengths, from the oligomer to unentangled Rouse like systems. The PE/Au interaction is parametrized via DFT calculations. By computing the different properties the concept of the interface, and the interphase as well, in polymer nanocomposites with metal NPs are critically examined. Results concerning polymer density profiles, bond order parameter, segmental and terminal dynamics show clearly that the size of the interface/interphase, depends on the actual property under study. In addition, the anchored polymeric chains change the behavior/properties, and especially the chain density profile and the dynamics, of the polymer chain at the vicinity of the Au NP.
Bonding and Thermal Cycling Performances of Two (Poly)Aryl–Ether–Ketone (PAEKs) Materials to an Acrylic Denture Base Resin
Authors: Peng Tzu-Yu , Shimoe Saiji , Fuh Lih-Jyh , Lin Chung-Kwei , Lin Dan-Jae , Kaku Masato
Published: February 2021

Poly(aryl–ether–ketone) materials (PAEKs) are gaining interest in everyday dental practices because of their natural properties. This study aims to analyze the bonding performance of PAEKs to a denture acrylic. Testing materials were pretreated by grinding, sandblasting, and priming prior to polymerization with the denture acrylic. The surface morphologies were observed using a scanning electron microscope and the surface roughness was measured using atomic force microscopy. The shear bond strength (SBS) values were determined after 0 and 2500 thermal cycles. The obtained data were analyzed using a paired samples t-test and Tukey’s honestly significant difference (HSD) test (α = 0.05). The surface characteristics of testing materials after different surface pretreatments showed obvious differences. PAEKs showed lower surface roughness values (0.02–0.03 MPa) than Co-Cr (0.16 MPa) and zirconia (0.22 MPa) after priming and sandblasting treatments (p < 0.05). The SBS values of PAEKs (7.60–8.38 MPa) met the clinical requirements suggested by ISO 10477 (5 MPa). Moreover, PAEKs showed significantly lower SBS reductions (p < 0.05) after thermal cycling fatigue testing compared to Co-Cr and zirconia. Bonding performance is essential for denture materials, and our results demonstrated that PAEKs possess good resistance to thermal cycling fatigue, which is an advantage in clinical applications. The results imply that PAEKs are potential alternative materials for the removable of prosthetic frameworks.
Unsupervised Change Detection from Remotely Sensed Images Based on Multi-Scale Visual Saliency Coarse-to-Fine Fusion
Authors: He Pengfei , Zhao Xiangwei , Shi Yuli , Cai Liping
Published: February 2021

Unsupervised change detection(CD) from remotely sensed images is a fundamental challenge when the ground truth for supervised learning is not easily available. Inspired by the visual attention mechanism and multi-level sensation capacity of human vision, we proposed a novel multi-scale analysis framework based on multi-scale visual saliency coarse-to-fine fusion (MVSF) for unsupervised CD in this paper. As a preface of MVSF, we generalized the connotations of scale as four classes in the field of remote sensing (RS) covering the RS process from imaging to image processing, including intrinsic scale, observation scale, analysis scale and modeling scale. In MVSF, superpixels were considered as the primitives for analysing the difference image(DI) obtained by the change vector analysis method. Then, multi-scale saliency maps at the superpixel level were generated according to the global contrast of each superpixel. Finally, a weighted fusion strategy was designed to incorporate multi-scale saliency at a pixel level. The fusion weight for the pixel at each scale is adaptively obtained by considering the heterogeneity of the superpixel it belongs to and the spectral distance between the pixel and the superpixel. The experimental study was conducted on three bi-temporal remotely sensed image pairs, and the effectiveness of the proposed MVSF was verified qualitatively and quantitatively. The results suggest that it is not entirely true that finer scale brings better CD result, and fusing multi-scale superpixel based saliency at a pixel level obtained a higher F1 score in the three experiments. MVSF is capable of maintaining the detailed changed areas while resisting image noise in the final change map. Analysis of the scale factors in MVSF implied that the performance of MVSF is not sensitive to the manually selected scales in the MVSF framework.
Analysis of the Monthly and Spring-Neap Tidal Variability of Satellite Chlorophyll-a and Total Suspended Matter in a Turbid Coastal Ocean Using the DINEOF Method
Authors: Yang Mengmeng , Khan Faisal Ahmed , Tian Hongzhen , Liu Qinping
Published: February 2021

Missing spatial data is one of the major concerns associated with the application of satellite data. The Data INterpolating Empirical Orthogonal Functions (DINEOF) method has been proven to be an effective tool for filling spatial gaps in various satellite data products. The Ariake Sea, which is a turbid coastal sea, shows the large spatial and temporal variability of chlorophyll-a (Chl-a) and total suspended matter (TSM). However, ocean color satellite data for this region usually have large gaps, which affects the accurate analysis of Chl-a and TSM variability. In this study, we applied the DINEOF method to fill the missing pixels from the regionally tuned Moderate Resolution Imaging Spectroradiometer (MODIS)-Aqua (hereafter, MODIS) Chl-a and MODIS-derived TSM datasets for the period 2002–2017. The validation results showed that the DINEOF reconstructed data were accurate and reliable. Furthermore, the Empirical Orthogonal Functions (EOF) analysis based on the reconstructed data was used to quantitatively analyze the spatial and temporal variability of Chl-a and TSM at both monthly and individual events of spring-neap tidal scales. The first three EOF modes of Chl-a showed seasonal variability mainly caused by precipitation, the sea surface temperature (SST), and river discharge for the first EOF mode and the sea level amplitude for the second. The first three EOF modes of TSM exhibited both seasonal and spring-neap tidal variability. The first and second EOF modes of TSM displayed spring-neap tidal variability caused by the sea level amplitude. The second EOF mode of TSM also showed seasonal variability caused by the sea level amplitude. In this study, we first applied the DINEOF method to reconstruct the satellite data and to capture the major spatial and temporal variability of Chl-a and TSM for the Ariake Sea. Our results demonstrate that the DINEOF method can reconstruct patchy oceanic color datasets and improve spatio-temporal variability analysis.
Assessment of Landsat Based Deep-Learning Membership Analysis for Development of from–to Change Time Series in the Prairie Region of Canada from 1984 to 2018
Authors: Pouliot Darren , Alavi Niloofar , Wilson Scott , Duffe Jason , Pasher Jon , Davidson Andrew , Daneshfar Bahram , Lindsay Emily
Published: February 2021

The prairie region of Canada is a dynamically changing landscape in relation to past and present anthropogenic activities and recent climate change. Improving our understanding of the rate, timing, and distribution of landscape change is needed to determine the impact on wildlife populations and biodiversity, ultimately leading to better-informed management regarding requirements for habitat amount and its connectedness. In this research, we assessed the viability of an approach to detect from–to class changes designed to be scalable to the prairie region with the capacity for local refinement. It employed a deep-learning convolutional neural network to model general land covers and examined class memberships to identify land-cover conversions. For this implementation, eight land-cover categories were derived from the Agriculture and Agri-Food Canada Annual Space-Based Crop Inventory. Change was assessed in three study areas that contained different mixes of grassland, pasture, and forest cover. Results showed that the deep-learning method produced the highest accuracy across all classes relative to an implementation of random forest that included some first-order texture measures. Overall accuracy was 4% greater with the deep-learning classifier and class accuracies were more balanced. Evaluation of change accuracy suggested good performance for many conversions such as grassland to crop, forest to crop, water to dryland covers, and most bare/developed-related changes. Changes involving pasture with grassland or cropland were more difficult to detect due to spectral confusion among classes. Similarly, conversion to forests in some cases was poorly detected due to gradual and subtle change characteristics combined with confusion between forest, shrub, and croplands. The proposed framework involved several processing steps that can be explored to enhance the thematic content and accuracy for large regional implementation. Evaluation for understanding connectivity in natural land covers and related declines in species at risk is planned for future research.
Shoreline Extraction in SAR Image Based on Advanced Geometric Active Contour Model
Authors: Wei Xueyun , Zheng Wei , Xi Caiping , Shang Shang
Published: February 2021

Rapid and accurate extraction of shoreline is of great significance for the use and management of sea area. Remote sensing has a strong ability to obtain data and has obvious advantages in shoreline survey. Compared with visible-light remote sensing, synthetic aperture radar (SAR) has the characteristics of all-weather and all-day working. It has been well-applied in shoreline extraction. However, due to the influence of natural conditions there is a problem of weak boundary in extracting shoreline from SAR images. In addition, the complex micro topography near the shoreline makes it difficult for traditional visual interpretation and image edge detection methods based on edge information to obtain a continuous and complete shoreline in SAR images. In order to solve these problems, this paper proposes a method to detect the land–sea boundary based on a geometric active contour model. In this method, a new symbolic pressure function is used to improve the geometric active-contour model, and the global regional smooth information is used as the convergence condition of curve evolution. Then, the influence of different initial contours on the number and time of iterations is studied. The experimental results show that this method has the advantages of fewer iteration times, good stability and high accuracy.
Historic and Simulated Desert-Oasis Ecotone Changes in the Arid Tarim River Basin, China
Authors: Sun Fan , Wang Yi , Chen Yaning , Li Yupeng , Zhang Qifei , Qin Jingxiu , Kayumba Patient Mindje
Published: February 2021

The desert-oasis ecotone, as a crucial natural barrier, maintains the stability of oasis agricultural production and protects oasis habitat security. This paper investigates the dynamic evolution of the desert-oasis ecotone in the Tarim River Basin and predicts the near-future land-use change in the desert-oasis ecotone using the cellular automata–Markov (CA-Markov) model. Results indicate that the overall area of the desert-oasis ecotone shows a shrinking trend (from 67,642 km2 in 1990 to 46,613 km2 in 2015) and the land-use change within the desert-oasis ecotone is mainly manifested by the conversion of a large amount of forest and grass area into arable land. The increasing demand for arable land for groundwater has led to a decline in the groundwater level, which is an important reason for the habitat deterioration in the desert-oasis ecotone. The rising temperature and drought have further exacerbated this trend. Assuming the current trend in development without intervention, the CA-Markov model predicts that by 2030, there will be an additional 1566 km2 of arable land and a reduction of 1151 km2 in forested area and grassland within the desert-oasis ecotone, which will inevitably further weaken the ecological barrier role of the desert-oasis ecotone and trigger a growing ecological crisis.
Exploring the Impact of Noise on Hybrid Inversion of PROSAIL RTM on Sentinel-2 Data
Authors: de Sá Nuno César , Baratchi Mitra , Hauser Leon T. , van Bodegom Peter
Published: February 2021

Remote sensing (RS) of biophysical variables plays a vital role in providing the information necessary for understanding spatio-temporal dynamics in ecosystems. The hybrid approach to retrieve biophysical variables from RS by combining Machine Learning (ML) algorithms with surrogate data generated by Radiative Transfer Models (RTM). The susceptibility of the ill-posed solutions to noise currently constrains further application of hybrid approaches. Here, we explored how noise affects the performance of ML algorithms for biophysical trait retrieval. We focused on synthetic Sentinel-2 (S2) data generated using the PROSAIL RTM and four commonly applied ML algorithms: Gaussian Processes (GPR), Random Forests (RFR), and Artificial Neural Networks (ANN) and Multi-task Neural Networks (MTN). After identifying which biophysical variables can be retrieved from S2 using a Global Sensitivity Analysis, we evaluated the performance loss of each algorithm using the Mean Absolute Percentage Error (MAPE) with increasing noise levels. We found that, for S2 data, Carotenoid concentrations are uniquely dependent on band 2, Chlorophyll is almost exclusively dependent on the visible ranges, and Leaf Area Index, water, and dry matter contents are mostly dependent on infrared bands. Without added noise, GPR was the best algorithm (<0.05%), followed by the MTN (<3%) and ANN (<5%), with the RFR performing very poorly (<50%). The addition of noise critically affected the performance of all algorithms (>20%) even at low levels of added noise (≈5%). Overall, both neural networks performed significantly better than GPR and RFR when noise was added with the MTN being slightly better when compared to the ANN. Our results imply that the performance of the commonly used algorithms in hybrid-RTM inversion are pervasively sensitive to noise. The implication is that more advanced models or approaches are necessary to minimize the impact of noise to improve near real-time and accurate RS monitoring of biophysical trait retrieval.
What Drives Crop Land Use Change during Multi-Year Droughts in California’s Central Valley? Prices or Concern for Water?
Authors: Gebremichael Mekonnen , Krishnamurthy P. Krishna , Ghebremichael Lula T. , Alam Sarfaraz
Published: February 2021

The recent multi-year droughts in California have highlighted the heightened risk of longer and more intense droughts, thus increasing the interest in understanding potential impacts for major economic activities, such as agriculture. This study examines changes in cropping pattern in California’s Central Valley between 2007 and 2016 in response to two consecutive droughts (2007–2009 and 2012–2016), factors driving these changes, and the impact of these changes on groundwater level. Results indicate that Central Valley experienced a shift in cropping pattern from alfalfa, cereals (rice, winter wheat, corn, and oats), and cotton, to nut (almonds, walnuts, and pistachios) and fruit (grapes, oranges, and tomatoes) tree crops. This shift in cropping pattern was likely driven by high crop prices, increasing trend in crop price, and increasing water pumping cost, particularly in the relatively water-stressed southern parts of Central Valley. While the total cropland water use for Central Valley remained the same during 2007–2016 (during both wet and dry years), they vary from county to county. Some counties experienced large reductions in cropland water use, while other counties experienced large increases in cropland water use, indicating the need for county-specific water resource management. The results also indicate that both land management (determining size of fallow land), as well as crop management (choice of crop types), are key factors in water resource management.
Hydroclimatic Extremes Evaluation Using GRACE/GRACE-FO and Multidecadal Climatic Variables over the Nile River Basin
Authors: Nigatu Zemede M. , Fan Dongming , You Wei , Melesse Assefa M.
Published: February 2021

Hydroclimatic extremes such as droughts and floods triggered by human-induced climate change are causing severe damage in the Nile River Basin (NRB). These hydroclimatic extremes are not well studied in a holistic approach in NRB. In this study, the Gravity Recovery and Climate Experiment (GRACE) mission and its Follow on mission (GRACE-FO) derived indices and other standardized hydroclimatic indices are computed for developing monitoring and evaluation methods of flood and drought. We evaluated extreme hydroclimatic conditions by using GRACE/GRACE-FO derived indices such as water storage deficits Index (WSDI); and standardized hydroclimatic indices (i.e., Palmer Drought Severity Index (PDSI) and others). This study showed that during 1950–2019, eight major floods and ten droughts events were identified based on standardized-indices and GRACE/GRACE-FO-derived indices. Standardized-indices mostly underestimated the drought and flood severity level compared to GRACE/GRACE-FO derived indices. Among standardized indices PDSI show highest correlation (r2 = 0.72) with WSDI. GRACE-/GRACE-FO-derived indices can capture all major flood and drought events; hence, it may be an ideal substitute for data-scarce hydro-meteorological sites. Therefore, the proposed framework can serve as a useful tool for flood and drought monitoring and a better understanding of extreme hydroclimatic conditions in NRB and other similar climatic regions.
Using UAV LiDAR to Extract Vegetation Parameters of Inner Mongolian Grassland
Authors: Zhang Xiang , Bao Yuhai , Wang Dongliang , Xin Xiaoping , Ding Lei , Xu Dawei , Hou Lulu , Shen Jie
Published: February 2021

The accurate estimation of grassland vegetation parameters at a high spatial resolution is important for the sustainable management of grassland areas. Unmanned aerial vehicle (UAV) light detection and ranging (LiDAR) sensors with a single laser beam emission capability can rapidly detect grassland vegetation parameters, such as canopy height, fractional vegetation coverage (FVC) and aboveground biomass (AGB). However, there have been few reports on the ability to detect grassland vegetation parameters based on RIEGL VUX-1 UAV LiDAR (Riegl VUX-1) systems. In this paper, we investigated the ability of Riegl VUX-1 to model the AGB at a 0.1 m pixel resolution in the Hulun Buir grazing platform under different grazing intensities. The LiDAR-derived minimum, mean, and maximum canopy heights and FVC were used to estimate the AGB across the entire grazing platform. The flight height of the LiDAR-derived vegetation parameters was also analyzed. The following results were determined: (1) The Riegl VUX-1-derived AGB was predicted to range from 29 g/m2 to 563 g/m2 under different grazing conditions. (2) The LiDAR-derived maximum canopy height and FVC were the best predictors of grassland AGB (R2 = 0.54, root-mean-square error (RMSE) = 64.76 g/m2). (3) For different UAV flight altitudes from 40 m to 110 m, different flight heights showed no major effect on the derived canopy height. The LiDAR-derived canopy height decreased from 9.19 cm to 8.17 cm, and the standard deviation of the LiDAR-derived canopy height decreased from 3.31 cm to 2.35 cm with increasing UAV flight altitudes. These conclusions could be useful for estimating grasslands in smaller areas and serving as references for other remote sensing datasets for estimating grasslands in larger areas.
Self- and Inter-Crossover Points of Jasons’ Missions as New Essential Add-on of Satellite Altimetry in the Sub-Arctic Seas and the Southern Ocean
Authors: Badulin Sergei , Kostianoy Andrey , Shabanov Pavel , Sharmar Vitali , Grigorieva Vika , Lebedev Sergey
Published: February 2021

For decades, satellite altimetry is providing reliable data on the sea level, surface currents, tides, planetary and wind waves and sea ice. We propose a potential enhancement of collecting special data subsets for a better temporal and spatial sampling of dynamics of the Sub-Polar seas. We show that peculiarities of the orbits of the TOPEX/Poseidon and Jasons’ missions generate a regular grid of crossovers which locations are fixed in space and time of the orbit cycles. Two types of these special crossovers are specified: self-crossovers (SC) occurring as intersections of tracks of the same satellite and inter-crossovers (IC) appearing during the phases of interleaved orbits when tracks of two different satellites are crossing. The time delay between two consecutive measurements in the high-latitude sites is less than 2 h for SC and 1 h for IC, thus providing a ground for monitoring large-scale currents (including current direction) and wind waves. The sets of the special crossovers can be regarded as networks of virtual ocean buoys. The Norwegian Sea case study illustrates the value of the special crossovers for the Sub-Polar seas and the feasibility of building the networks of SC and IC in other areas of the World Ocean.
Analysis of Atmospheric and Ionospheric Variations Due to Impacts of Super Typhoon Mangkhut (1822) in the Northwest Pacific Ocean
Authors: Freeshah Mohamed , Zhang Xiaohong , Şentürk Erman , Adil Muhammad Arqim , Mousa B. G. , Tariq Aqil , Ren Xiaodong , Refaat Mervat
Published: February 2021

The Northwest Pacific Ocean (NWP) is one of the most vulnerable regions that has been hit by typhoons. In September 2018, Mangkhut was the 22nd Tropical Cyclone (TC) over the NWP regions (so, the event was numbered as 1822). In this paper, we investigated the highest amplitude ionospheric variations, along with the atmospheric anomalies, such as the sea-level pressure, Mangkhut’s cloud system, and the meridional and zonal wind during the typhoon. Regional Ionosphere Maps (RIMs) were created through the Hong Kong Continuously Operating Reference Stations (HKCORS) and International GNSS Service (IGS) data around the area of Mangkhut typhoon. RIMs were utilized to analyze the ionospheric Total Electron Content (TEC) response over the maximum wind speed points (maximum spots) under the meticulous observations of the solar-terrestrial environment and geomagnetic storm indices. Ionospheric vertical TEC (VTEC) time sequences over the maximum spots are detected by three methods: interquartile range method (IQR), enhanced average difference (EAD), and range of ten days (RTD) during the super typhoon Mangkhut. The research findings indicated significant ionospheric variations over the maximum spots during this powerful tropical cyclone within a few hours before the extreme wind speed. Moreover, the ionosphere showed a positive response where the maximum VTEC amplitude variations coincided with the cyclone rainbands or typhoon edges rather than the center of the storm. The sea-level pressure tends to decrease around the typhoon periphery, and the highest ionospheric VTEC amplitude was observed when the low-pressure cell covers the largest area. The possible mechanism of the ionospheric response is based on strong convective cells that create the gravity waves over tropical cyclones. Moreover, the critical change state in the meridional wind happened on the same day of maximum ionospheric variations on the 256th day of the year (DOY 256). This comprehensive analysis suggests that the meridional winds and their resulting waves may contribute in one way or another to upper atmosphere-ionosphere coupling.
A Track-Before-Detect Strategy Based on Sparse Data Processing for Air Surveillance Radar Applications
Authors: Fiscante Nicomino , Addabbo Pia , Clemente Carmine , Biondi Filippo , Giunta Gaetano , Orlando Danilo
Published: February 2021

In this paper we consider the tracking problem of a moving target competing against noise and clutter in a surveillance radar scenario. For a single array-antenna multiple-target tracking system and according to the Track-Before-Detect paradigm, we present a novel approach based on a three-stage processing chain that involves the Sparse Learning via Iterative Minimization algorithm, the k-means clustering method and the ad hoc detector by exploiting the sparse nature of the operating scenario. Under the latter assumption, the detection strategy declares the presence of targets subsequently to the retrieval of their corresponding tracks performed by jointly processing the received echoes of multiple consecutive radar scans. Simulation results show that the proposed approach is able to provide good tracking and detection capabilities for different multiple target trajectories with low Signal-to-Interference-plus-Noise ratio and results in providing advantages when compared to a number of other reference Track-Before-Detect strategies based on sparse data processing techniques.
Assessing Urbanization Dynamics in Turkey’s Marmara Region Using CORINE Data between 2006 and 2018
Authors: Genel Özlem Altınkaya , Guan ChengHe
Published: February 2021

This study investigated the urban growth dynamics of urban regions. The study area was the Marmara Region, one of the most densely populated and ecologically diverse areas in Turkey. Using CORINE land cover data for 2006, 2012, and 2018, the study utilized multiple correspondence analyses and cluster analyses, to analyze land cover changes. The resulting maps, visualized in GIS, revealed the rapid urban transformation of the regional structure, formerly comprised of four distinct areas, into a more complex structure, in which densification and sprawl occur simultaneously. Our findings demonstrated a dissonance between the spatial dynamics of the Marmara Region during the study period, and the capacity and scope of the simultaneously initiated regional policies and mega-projects. This uncoordinated approach has endangered the region’s sustainable development. The paper, therefore, discusses the importance of land use planning and transboundary collaboration for sustainable regional development. Beyond the local case, the results contribute to critical theories in regional planning by linking theory and practice.
Airborne Ground Penetrating Radar, Field Test
Authors: Edemsky Dmitry , Popov Alexei , Prokopovich Igor , Garbatsevich Vladimir
Published: February 2021

Deployment of a ground penetrating radar (GPR) on a flying machine allows one to substantially extend the application area of this geophysical method and to simplify carrying out large surveys of dangerous and hard-to-reach terrain, where usual ground-based methods are hardly applied. There is a necessity to promote investigations in this direction by modifying hardware characteristics and developing specific proceeding algorithms. For this purpose, we upgraded commercial ground-based subsurface sounding hardware and performed corresponding computer simulation and real experiments. Finally, the first experimental flights were done with the constructed GPR prototype mounted on a helicopter. Using our experience in the development of ground-based GPR and the results of numerical simulations, an appropriate configuration of antennas and their placing on the flying machine were chosen. Computer modeling allowed us to select an optimal resistive loading of transmitter and receiver dipoles; calculate radiation patterns on fixed frequencies; analyze the efficiency of different conductor diameters in antenna circuit; calculate cross-coupling of transmitting and receiving antennas with the helicopter. Preliminary laboratory experiments to check the efficiency of the designed system were performed on an urban building site, using a tower crane with the horizontal jib to operate the measuring system in the air above the ground area to be sounded. Both signals from the surface and subsurface objects were recorded. To interpret the results, numerical modeling was carried out. A two-dimensional model of our experiment was simulated, it matches well the experimental data. Laboratory experiments provided an opportunity to estimate the level of spurious reflections from the external objects, which helps to recognize weak signals from subsurface objects in GPR surveys under live conditions.
Integrated Quad-Scanner Strategy-Based Optical Coherence Tomography for the Whole-Directional Volumetric Imaging of a Sample
Authors: Saleah Sm Abu , Seong Daewoon , Han Sangyeob , Wijesinghe Ruchire Eranga , Ravichandran Naresh Kumar , Jeon Mansik , Kim Jeehyun
Published: February 2021

Whole-directional scanning methodology is required to observe distinctive features of an entire physical structure with a three dimensional (3D) visualization. However, the implementation of whole-directional scanning is challenging for conventional optical coherence tomography (OCT), which scans a limited portion of the sample by utilizing unidirectional and bidirectional scanning methods. Therefore, in this paper an integrated quad-scanner (QS) strategy-based OCT method was implemented to obtain the whole-directional volumetry of a sample by employing four scanning arms installed around the sample. The simultaneous and sequential image acquisition capabilities are the conceptual key points of the proposed QS-OCT method, and were implemented using four precisely aligned scanning arms and applied in a complementary way according to the experimental criteria. To assess the feasibility of obtaining whole-directional morphological structures, a roll of Scotch tape, an ex vivo mouse heart, and kidney specimens were imaged and independently obtained tissue images at different directions were delicately merged to compose the 3D volume data set. The results revealed the potential merits of QS-OCT-based whole-directional imaging, which can be a favorable inspection method for various discoveries that require the dynamic coordinates of the whole physical structure.
Dynamic Bandwidth Part Allocation in 5G Ultra Reliable Low Latency Communication for Unmanned Aerial Vehicles with High Data Rate Traffic
Authors: Han Minsig , Lee Jaewon , Rim Minjoong , Kang Chung G.
Published: February 2021

The 3GPP standardized the physical layer specification in 5G New Radio to support enhanced mobile broadband (eMBB) and ultra-reliable low-latency communication (URLLC) coexistence in usage scenarios including aerial vehicles (AVs). Dynamic multiplexing of URLLC traffic was standardized to increase the outage capacity. DM allocates a fully overlapped bandwidth part (BWP) of eMBB and URLLC AVs to perform the immediate scheduling of URLLC traffic by puncturing ongoing eMBB traffic. However, DM often suffers from a significant frame error incurred by puncturing. Meanwhile, BWP can be sliced orthogonally for eMBB and URLLC AVs, possibly preventing overdimensioning the resources depending on the eMBB and URLLC traffic loads. In this paper, we propose a dynamic BWP allocation scheme that switches between two multiplexing methods, dynamic multiplexing (DM) and orthogonal slicing (OS), so as to minimize an impact of uRLLC traffic on eMBB traffic. To implement efficient BWP allocation, the capacity region is analyzed by considering the effect of physical layer parameters, such as modulation and coding scheme (MCS) levels and code block group size on DM and OS. OS is effective for improving the eMBB throughput under a URLLC latency constraint for deterministic and predictable URLLC traffic, whereas DM has limited error-correcting capability against the URLLC’s puncturing effect. The relative MCS level of eMBB and URLLC is critical in determining the eMBB traffic tolerance against puncturing. Identifying the performance tradeoff between DM and OS, the tolerance level is quantified by a URLLC load threshold. It is given in an approximate closed form, which is an essential reference for selecting DM over OS, enabling dynamic BWP allocation for the URLLC AV.
Estimation of Wave Period from Pitch and Roll of a Lidar Buoy
Authors: Salcedo-Bosch Andreu , Rocadenbosch Francesc , Gutiérrez-Antuñano Miguel A. , Tiana-Alsina Jordi
Published: February 2021

This work proposes a new wave-period estimation (L-dB) method based on the power-spectral-density (PSD) estimation of pitch and roll motional time series of a Doppler wind lidar buoy under the assumption of small angles (±22 deg) and slow yaw drifts (1 min), and the neglection of translational motion. We revisit the buoy’s simplified two-degrees-of-freedom (2-DoF) motional model and formulate the PSD associated with the eigenaxis tilt of the lidar buoy, which was modelled as a complex-number random process. From this, we present the L-dB method, which estimates the wave period as the average wavelength associated to the cutoff frequency span at which the spectral components drop off L decibels from the peak level. In the framework of the IJmuiden campaign (North Sea, 29 March–17 June 2015), the L-dB method is compared in reference to most common oceanographic wave-period estimation methods by using a TriaxysTM buoy. Parametric analysis showed good agreement (correlation coefficient, ρ = 0.86, root-mean-square error (RMSE) = 0.46 s, and mean difference, MD = 0.02 s) between the proposed L-dB method and the oceanographic zero-crossing method when the threshold L was set at 8 dB.
Managing Expectations: Impacts of Hostile Migration Policies on Practitioners in Britain, Denmark and Sweden
Authors: Canning Victoria
Published: February 2021

The acknowledgement that asylum systems across Europe are “hostile environments” for migrant groups has increased in academic and practitioner consciousness, particularly in the aftermath of the 2015 refugee reception crisis. However, although the impacts of socio-political hostilities on migrants are well documented, little has been written about the implications of border restrictions on practitioners working with refugee populations. This article expands the focus of hostilities to consider the variable impacts of intensified bordering practices on this group. Based on qualitative research which included 74 interviews undertaken across Britain, Denmark, and Sweden (2016–2018), it outlines the experiences of practitioners working with refugee populations. It highlights that increasingly restrictive or punitive approaches to immigration have had multiple negative effects on practitioners working in this sector. This has potential for longer term negative impacts on practitioners, but also—importantly-refugee populations who require various forms of legal aid, or social and psychological support.
Young Teenagers’ Views Regarding Residential Care in Portugal and Spain: A Qualitative Study
Authors: Montserrat Carme , Delgado Paulo , Garcia-Molsosa Marta , Carvalho João M. S. , Llosada-Gistau Joan
Published: February 2021

Research on residential care has been well established in the literature. Nonetheless, research drawing from the actual experiences of adolescents is relatively scarce. A qualitative study was designed highlighting the voices of children, analysing their fostering experience, interpersonal relationships, their participation in daily decisions, and future aspirations. The sample included 33 early adolescents in residential care aged 12–14 in Portugal (n = 17) and Spain (n = 16). Results showed that there was agreement in terms of the importance given to education, their satisfaction with the material conditions of residential centre, and their dissatisfaction concerning matters of individuality, autonomy, participation, and socialization.
Footwear Affects Conventional and Sumo Deadlift Performance
Authors: Valenzuela Kevin A. , Walters Kellie A. , Avila Elizabeth L. , Camacho Alexis S. , Alvarado Fany , Bennett Hunter J.
Published: February 2021

Barefoot weightlifting has become a popular training modality in recent years due to anecdotal suggestions of improved performance. However, research to support these anecdotal claims is limited. Therefore, the purpose of this study was to assess the differences between the conventional deadlift (CD) and the sumo deadlift (SD) in barefoot and shod conditions. On day one, one-repetition maximums (1 RM) were assessed for thirty subjects in both the CD and SD styles. At least 72 h later, subjects returned to perform five repetitions in four different conditions (barefoot and shod for both CD and SD) at 70% 1 RM. A 2 × 2 (footwear × lifting style) MANOVA was used to assess differences between peak vertical ground reaction force (VGRF), total mechanical work (WORK), barbell vertical displacement (DISP), peak vertical velocity (PV) and lift time (TIME) during the concentric phase. The CD displayed significant increases in VGRF, DISP, WORK, and TIME over the SD. The shod condition displayed increased WORK, DISP, and TIME compared to the barefoot condition. This study suggests that lifting barefoot does not improve performance as no differences in VGRF or PV were evident. The presence of a shoe does appear to increase the DISP and WORK required to complete the lift, suggesting an increased work load is present while wearing shoes.
Does Facilitating Human–Place Bonds Alleviate the Negative Effects of Incivilities on Health?
Authors: Hedayati Marzbali Massoomeh , Safizadeh Mina , Tilaki Mohammad Javad Maghsoodi , Abdullah Aldrin
Published: February 2021

The present study has two purposes—methodological and theoretical. The methodological purpose is to examine a method for the analysis of perceived incivilities and health in urban neighbourhoods. The current study investigates the direct and indirect relationships between the two variables. The theoretical purpose is to measure neighbourhood incivility as a second-order latent variable that represents physical and social incivilities, and investigates place identity and place attachment as mediators in the relationship between incivilities and health. Previous research has focused on a single dimension of incivility. By contrast, the current study considers a multidimensional form of incivility. This quantitative study comprises 265 residents from an urban neighbourhood in Penang, Malaysia. The results of the structural equation modelling suggest that perceptions towards neighbourhood play a mediating role in the relationship between incivility and health. The mediation roles of place identity and place attachment in the relationship between incivilities and health are also supported. Thus, facilitating human–place bonds alleviates the negative effects of incivilities on health in the study neighbourhood. Residents are less attached to neighbourhoods that are perceived as socially and physically deteriorated. Thus, reducing incivilities and improving place attachment may enhance neighbourhood health.
On Sustainable|Sustaining City Streets
Authors: Tamminga Ken , Knüvener Thomas
Published: February 2021

City streets have long been the subject and context for research [...]
Numerical Investigation for Riverbank Filtration Sustainability Considering Climatic Changes in Arid and Semi-Arid Regions; Case Study of RBF Site at Embaba, Nile Delta, Egypt
Authors: Abd-Elaty Ismail , Ghanayem Hala M. , Zeleňáková Martina , Mésároš Peter , Saleh Osama K.
Published: February 2021

Changes in riverine hydrography and reduced aquifer recharge due to projected climate changes in arid and semi-arid regions are the main issues of water supply, especially in the Nile Delta, Egypt. Continuous degradation results from reduced Nile water flow, poor management of groundwater extraction, and human activities throughout the Nile’s course and drainage channels. Contamination of this water with heavy metals and dissolved organic solids reduces the quality of this water, which increases the price of treatment. River Bank Filtration (RBF) is a water treatment technology used for improving the quality of drinking water taken from polluted rivers where abstraction wells are installed on the banks. This study was applied to the RBF site at Embaba, Nile Delta, Egypt using the numerical code MT3D. The study was simulated and calibrated for the current situation and number of scenarios to investigate the effect of climatic changes on RBF sustainability. Four scenarios were simulated to identify and estimate the RBF portion and the total water travel time from the river to the wells. The first scenario involves a reduction in river stages, the second a decrease in aquifer recharge, the third a combination of the first two scenarios, and the fourth scenario combines scenarios 1, 2, and 3. The results indicate that the RBF portion decreased from 67.42% in the base case to 35.46% and 64.99% with a reduction in river stage by 75% from the base case and a decrease in aquifer recharge from 182.50 (base case) to 50 mm per year, respectively. Moreover, the RBF portion increased to reach 87.75% with a reduction in the General Head Boundary of 75% from the base case, while the combination of the three scenarios decreased the RBF portion to 67.24%. Finally, the water supply systems in arid and semi-arid regions should be extended by installing and operating RBF facilities to manage the negative effects of climatic change through reduction in river stages and aquifer recharge, and increasing abstraction due to overpopulation.