bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Mineral and Organic Fertilization on desi and kabuli Chickpea (Cicer arietinum L.): Plant Growth and Production, Hydration Properties, Bioactive Compounds, and Antioxidant Activity
Authors: Pasqualone Antonella , Summo Carmine , De Angelis Davide , Cucci Giovanna , Caranfa Davide , Lacolla Giovanni
Published: July 2021

Composting is a strategic technology to convert organic waste into environmentally friendly soil improvers, mitigating the pressure on landfills and contributing to sustainability. This research evaluates the effects of different doses of mineral/organic fertilizers on two chickpea types: desi and kabuli. A randomized block design with three replications and six conditions was adopted: non-fertilized control, two mineral fertilizations (M1, M2), and three organic fertilizations (B1, B2, B3). M1 and B1 provided for comparable NPK amounts. Fertilization and variety significantly influenced plant growth and production, and seed hydration. Fertilization had a lower influence on bioactive compounds. The highest seed yields were obtained with M2 (30–40–100 kg ha−1 of N, P2O5, and K2O, respectively. An addition of 40 kg ha−1 of P2O5 (M1) had no effect on seed yield. B1 (10 Mg ha−1 of Bio Vegetal) and M1 led to the same yield, which did not increase using higher doses of green compost. Mineral and organic fertilizations favored hydration and swelling of chickpeas. Desi chickpea showed a significantly higher seed yield but a lower seed weight than kabuli. Organic fertilization, combined with the recovery of peculiar chickpeas, which are more productive and richer in bioactive compounds, promotes a more sustainable food system.
Leaf Plasmodesmata Respond Differently to TMV, ToBRFV and TYLCV Infection
Authors: Kutsher Yaarit , Evenor Dalia , Belausov Eduard , Lapidot Moshe , Reuveni Moshe
Published: July 2021

Macromolecule and cytosolic signal distribution throughout the plant employs a unique cellular and intracellular mechanism called plasmodesmata (PD). Plant viruses spread throughout plants via PD using their movement proteins (MPs). Viral MPs induce changes in plasmodesmata’s structure and alter their ability to move macromolecule and cytosolic signals. The developmental distribution of a family member of proteins termed plasmodesmata located proteins number 5 (PDLP5) conjugated to GFP (PDLP5-GFP) is described here. The GFP enables the visual localization of PDLP5 in the cell via confocal microscopy. We observed that PDLP5-GFP protein is present in seed protein bodies and immediately after seed imbibition in the plasma membrane. The effect of three different plant viruses, the tobacco mosaic virus (TMV), tomato brown rugose fruit virus (ToBRFV, tobamoviruses), and tomato yellow leaf curl virus (TYLCV, begomoviruses), on PDLP5-GFP accumulation at the plasmodesmata was tested. In tobacco leaf, TMV and ToBRFV increased PDLP5-GFP amount at the plasmodesmata of cell types compared to control. However, there was no statistically significant difference in tomato leaf. On the other hand, TYLCV decreased PDLP5-GFP quantity in plasmodesmata in all tomato leaf cells compared to control, without any significant effect on plasmodesmata in tobacco leaf cells.
Electrically Tuneable Optical Diffraction Gratings Based on a Polymer Scaffold Filled with a Nematic Liquid Crystal
Authors: Bošnjaković Dejan , Fleisch Mathias , Zhang Xinzheng , Drevenšek-Olenik Irena
Published: July 2021

We present an experimental and theoretical investigation of the optical diffractive properties of electrically tuneable optical transmission gratings assembled as stacks of periodic slices from a conventional nematic liquid crystal (E7) and a standard photoresist polymer (SU-8). The external electric field causes a twist-type reorientation of the LC molecules toward a perpendicular direction with respect to initial orientation. The associated field-induced modification of the director field is determined numerically and analytically by minimization of the Landau–de Gennes free energy. The optical diffraction properties of the associated periodically modulated structure are calculated numerically on the basis of rigorous coupled-wave analysis (RCWA). A comparison of experimental and theoretical results suggests that polymer slices provoke planar surface anchoring of the LC molecules with the inhomogeneous surface anchoring energy varying in the range 5–20 μJ/m2. The investigated structures provide a versatile approach to fabricating LC-polymer-based electrically tuneable diffractive optical elements (DOEs).
Rheological Characterization and Modeling of Thermally Unstable Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)
Authors: Lajewski Silvia , Mauch Annika , Geiger Kalman , Bonten Christian
Published: July 2021

Presently, almost every industry uses conventional plastics. Its production from petroleum and extensive plastic pollution cause environmental problems. More sustainable alternatives to plastics include bioplastics such as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), which is produced by bacteria and is biodegradable even in seawater. High temperature sensitivity as well as massive thermal degradation cause difficulties during the processing of PHBV. The aim of this work is to create a detailed rheological characterization and master curves to gain deeper knowledge about the material and its processing parameters. The rheological characterization was performed with frequency sweeps in the range of 0.1 rad/s to 628 rad/s and time sweeps over 300 s. Creating master curves at the reference temperature of 180 °C with the software IRIS delivers Carreau and Arrhenius parameters. These parameters allow for a calculation of the master curves for all other temperatures by means of the temperature shift factor. Moreover, the rheological measurements reveal a minimum rheological measurement temperature of 178 °C and a surprisingly high activation energy of 241.8 kJ/mol.
Dual-Sizing Effects of Carbon Fiber on the Thermal, Mechanical, and Impact Properties of Carbon Fiber/ABS Composites
Authors: Hwang Daekyun , Lee Seung Goo , Cho Donghwan
Published: July 2021

Dual-sizing effects with either epoxy or polyurethane (PU) on the thermal, mechanical, and impact properties of carbon fiber/acrylonitrile-butadiene-styrene (ABS) composites produced by extrusion and injection molding processes were investigated. The heat deflection temperature, dynamic mechanical, tensile, flexural, and impact properties of the composites reinforced with either (epoxy + epoxy) or (epoxy + PU) dual-sized carbon fiber were higher than those commercially single-sized with epoxy. The result indicated that the dual-sized carbon fiber significantly contributed not only to improving the heat deflection temperature and the storage modulus, but also to improving the tensile, flexural, and impact properties of carbon fiber/ABS composites. The highest improvement of the composite properties was obtained from the composite with (epoxy + PU) dual-sized carbon fiber. The improvement of the mechanical and impact properties was explained by the enhanced interfacial bonding between carbon fiber and ABS matrix and by the length distribution analysis of carbon fibers present in the resulting composites. The fiber–matrix interfacial behavior was qualitatively well-supported in terms of fiber pull-out, fiber breaking pattern, and debonding gaps between the fiber and the matrix, as observed from the fracture surface topography. This study revealed that the properties of carbon fiber/ABS composites prepared by extrusion and injection molding processes were improved by dual-sizing carbon fiber, which was performed after a commercial epoxy sizing process, and further improved by using PU as an additional sizing material.
Tuning the Surface Wettability of Cyclic Olefin Copolymer by Plasma Treatment and Graphene Oxide Deposition and Reduction
Authors: Dawaymeh Fadi , Abbas Yawar , Khaleel Maryam , Alazzam Anas , Alamoodi Nahla
Published: July 2021

Selective altering of surface wettability in microfluidic channels provides a suitable platform for a large range of processes, such as the phase separation of multiphase systems, synthesis of reaction controlled, nanoliter sized droplet reactors, and catalyst impregnation. Herein we study the feasibility to tune the wettability of a flexible cyclic olefin copolymer (COC). Two methods were considered for enhancing the surface hydrophilicity. The first is argon/oxygen plasma treatment, where the effect of treatment duration on water contact angle and COC surface morphology and chemistry were investigated, and the second is coating COC with GO dispersions of different concentrations. For enhancing the hydrophobicity of GO-coated COC surfaces, three reduction methods were considered: chemical reduction by Hydroiodic acid (HI), thermal reduction, and photo reduction by exposure of GO-coated COC to UV light. The results show that as the GO concentration and plasma treatment duration increased, a significant decrease in contact angle was observed, which confirmed the ability to enhance the wettability of the COC surface. The increase in hydrophilicity during plasma treatment was associated with the increase in surface roughness on the treated surfaces, while the increase during GO coating was associated with introducing oxygen-containing groups on the GO-coated COC surfaces. The results also show that the different reduction methods considered can increase the contact angle and improve the hydrophobicity of a GO-coated COC surface. It was found that the significant improvement in hydrophobicity was related to the reduction of oxygen-containing groups on the GO-coated COC modified surface.
Lignin-Based Gel Polymer Electrolyte for Cationic Conductivity
Authors: Shabanov Nabi S. , Rabadanov Kamil Sh. , Gafurov Malik M. , Isaev Abdulgalim B. , Sobola Dinara S. , Suleimanov Sagim I. , Amirov Akhmed M. , Asvarov Abil Sh.
Published: July 2021

The article presents the results of the preparation and study of a gel-polymer electrolyte based on lignin obtained from Pinus sylvestris. Sulfonation and subsequent chlorination of lignin make possible implementation of the principle of mono-ionic conductivity in a natural biopolymer matrix, which provides predominantly cationic conductivity of the electrolyte. Based on the results of the qualitative and quantitative analysis of the synthesized samples, the mechanisms of the chemical conversion of the biopolymer, the structure models of the converted fragments of macromolecules, as well as the quantum-chemical calculation of their electronic and geometric parameters are presented. The key electronic characteristics of the gel polymer electrolytes (GPE) based on a composite of lignins with 20 wt.% polyvinyl alcohol are determined by impedance spectroscopy. The maximum value of the specific volume conductivity is 2.48 × 10−4 S cm−1, which is comparable with most commercial electrolytes of this type, but at the same time, record values are reached in the number of lithium cation transfer tLi+ of 0.89. The studies allow to identify the basic laws of the effect of chemical modification on the structure of GPE and describe the mechanism of ionic conductivity.
Structure/Properties Relationship of Anionically Synthesized Diblock Copolymers “Grafted to” Chemically Modified Graphene
Authors: Katsigiannopoulos Dimitrios , Grana Eftychia , Tsitoni Konstantina , Moutsios Ioannis , Manesi Gkreti-Maria , Nikitina Evgeniia A. , Chalmpes Nikolaos , Moschovas Dimitrios , Gournis Dimitrios , Ivanov Dimitri A. , Avgeropoulos Apostolos
Published: July 2021

A novel approach to obtaining nanocomposite materials using anionic sequential polymerization and post-synthetic esterification reactions with chemically modified graphene sheets (CMGs) is reported. The anionically synthesized diblock copolymer precursors of the PS-b-PI-OH type were grafted to the chemically modified –COOH groups of the CMGs, giving rise to the final composite materials, namely polystyrene-b-poly(isoprene)-g-CMGs, which exhibited enhanced physicochemical properties. The successful synthesis was determined through multiple molecular characterization techniques together with thermogravimetric analysis for the verification of increased thermal stability, and the structure/properties relationship was justified through transmission electron microscopy. Furthermore, the arrangement of CMGs utilizing lamellar and cylindrical morphologies was studied in order to determine the effect of the loaded CMGs in the adopted topologies.
Rheology of Polymer Processing in Spain (1995–2020)
Authors: Sangroniz Leire , Fernández Mercedes , Partal Pedro , Santamaria Antxon
Published: July 2021

The contribution of Spanish scientists to the rheology involved in polymer processing during the last 25 years is investigated. It is shown that the performed research covers, at different levels, all industrial polymeric materials: thermoplastics, thermosets, adhesives, biopolymers, composites and nanocomposites, and polymer modified bitumen. Therefore, the rheological behaviour of these materials in processing methods such as extrusion, injection moulding, additive manufacturing, and others is discussed, based on the literature results. A detailed view of the most outstanding achievements, based on the rheological criteria of the authors, is offered.
Dynamic Processes and Mechanisms Involved in Relaxations of Single-Chain Nano-Particle Melts
Authors: Maiz Jon , Verde-Sesto Ester , Asenjo-Sanz Isabel , Malo de Molina Paula , Frick Bernhard , Pomposo José A. , Arbe Arantxa , Colmenero Juan
Published: July 2021

We present a combined study by quasielastic neutron scattering (QENS), dielectric and mechanical spectroscopy, calorimetry and wide-angle X-ray diffraction on single-chain nano-particles (SCNPs), using the corresponding linear precursor chains as reference, to elucidate the impact of internal bonds involving bulky cross-links on the properties of polymer melts. Internal cross-links do not appreciably alter local properties and fast dynamics. This is the case of the average inter-molecular distances, the β-relaxation and the extent of the atomic displacements at timescales faster than some picoseconds. Contrarily, the α-relaxation is slowed down with respect to the linear precursor, as detected by DSC, dielectric spectroscopy and QENS. QENS has also resolved broader response functions and stronger deviations from Gaussian behavior in the SCNPs melt, hinting at additional heterogeneities. The rheological properties are also clearly affected by internal cross-links. We discuss these results together with those previously reported on the deuterated counterpart samples and on SCNPs obtained through a different synthesis route to discern the effect of the nature of the cross-links on the modification of the diverse properties of the melts.
The Myth of Faust, “Titanism”, and the Religious Topic of the Selling of the Soul in the Cultural Writings of Jan Patočka
Authors: James Petra
Published: July 2021

The intensive and systematic scholarly interest in the relation of Patočka’s phenomenology to religion and Christianity is recent and has only intensified over the last ten years. Thus far, the topic has mainly been studied from philosophical and theological perspectives, and the extensive body of Patočka’s cultural writings has largely failed to attract the attention of scholars. Moreover, a culturological approach is virtually absent. Therefore, this article suggests focusing on the analysis of cultural archetypes in Patočka’s cultural writings related to the topic of religion and Christianity from this perspective. The cultural archetypes of the Faustian figures of Patočka’s cultural writings, whether Goethe’s Faust, Goethe’s Marguerite, or Mann’s Adrian Leverkühn, are all Socratic-Christic avatars that personify Patočka’s philosophical concept of “care for the soul” in the modern age. The legacy of Plato’s Greek philosophy and that of Western Christianity as presented by Patočka insist on the universally shared existential experience of finitude that should be grasped as a positive challenge in the strife for meaning. Patočka’s “titanism” and the archetypal titanic figures of his cultural writings are Patočkian manifestations of this universal effort. A culturological approach to Patočka’s thinking on religion and Christianity might thus prove most relevant.
Speech Genres and Interpretation of the Qur’an
Authors: Stewart Devin J.
Published: July 2021

This essay provides an overview of the investigation of genres in Qur’anic studies to date and argues for the utility of the theory of speech genres for the interpretation of the Qur’an generally. Drawing on this approach, it addresses several Qur’anic passages whose interpretation has been a matter of debate. Attention to the generic conventions of the various types of speech that are contained in Islam’s sacred text may help resolve a number of long-standing and current interpretive debates.
Beyond Secularization and Post-Secularity—Joseph Ratzinger’s and Józef Tischner’s Concept of a Breakthrough
Authors: Jagiełło Jarosław
Published: July 2021

The inspiration to write this article was provided by the assessment made by Joseph Ratzinger/Benedict XVI: man of the Western civilization is undergoing a deep spiritual crisis. Therefore, conversion, a breakthrough, or spiritual renewal is absolutely necessary. Without this renewal, humanity will become a victim of its own thinking, wanting and acting. As I search for a philosophical description of the breakthrough postulated by Benedict XVI, I refer to the original philosophical and religious thought of Polish philosopher Józef Tischner, who presents the question of the breakthrough at the anthropological-axiological level, where he exposes the issue of interpersonal correlation. The basis for the permanent existence of this correlation is man’s ethical awareness grounded in the ethic of dialogue. This grounding is particularly important, because it is a guarantee for overcoming internal and external threats to the existence of a religious community. Tischner presents the issue of this grounding against the background of the secularization of Western society. By distinguishing relative secularization from radical secularization, Tischner provides an insightful analysis of the phenomenon of the apparent and the true sacrum. For a real breakthrough, only the true sacrum, which Tischner believes to appear at the level of the Christian sanctum, is of primary importance. He understands sanctum as holiness grounded in goodness. It is holiness that is the real key to overcoming man’s multiple crises at the level of his thinking and religious life, at the level of both his private and social life. The presence of sanctum in human life constitutes, in Tischner’s view, the very core of the breakthrough and an expression of the important significance of religion in both individual and social human life. According to Tischner, it is owing to the presence of sanctum, i.e., that which is absolutely good, that man does not have to fall into the trap of post-secular thinking. For post-secularity, as Tischner believes, seeks ways to overcome the tension between the secularized world and the world of religion only in renouncing, for epistemic reasons, the absolutization of secular reason. In his opinion, however, this is not enough for believers and non-believers to follow a common path of cultivating the heritage of universal principles and values, historically expressed mainly in religious life. Only the capacity for selfless kindness can serve as the basic condition for both believers and non-believers to understand and preserve this heritage.
The Experience and Correlates of God’s Silence among Christians
Authors: Prusak Jacek , Wasiewicz Jakub
Published: July 2021

The aim of the study was to find out if Christians experience God’s silence and if so, what are its correlates during the COVID-19 pandemic. The second purpose of the study was to identify the connections between the experience of God’s silence and depressive mood disorders and the impact of God’s silence on other spiritual experiences. The study was conducted online on a group of 771 people, mostly Christians. The experience of God’s silence was declared by 82.1% of the respondents. This experience does not depend on the sex of the respondents, but correlates with their age. The experience of God’s silence is commensurate with the joy that comes from having a relationship with God through daily spiritual experiences. Additionally, the conducted research shows that experience of God’s silence resembles a state rather than a permanent feature with a visible ending, which is associated with a change in the image of God. The consequences of experiencing God’s silence need not to be negative. The conducted research shows that the most frequently mentioned effect of this experience is the strengthening and consolidation of faith.
Global Estimation and Assessment of Monthly Lake/Reservoir Water Level Changes Using ICESat-2 ATL13 Products
Authors: Xu Nan , Zheng Huiying , Ma Yue , Yang Jian , Liu Xinyuan , Wang Xiaohua
Published: July 2021

Accurate and detailed information on lake/reservoir water levels and temporal changes around the globe is urgently required for water resource management and related studies. The traditional satellite radar altimeters normally monitor water level changes of large lakes and reservoirs (i.e., greater than 1 km2) around the world. Fortunately, the recent Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) makes it possible to monitor water level changes for some small lakes and reservoirs (i.e., less than 1 km2). ICESat-2 ATL13 products provide observations of inland water surface heights, which are suitable for water level estimation at a global scale. In this study, ICESat-2 ATL13 products were used to conduct a global estimation and assessment of lake/reservoir water level changes. We produced monthly water levels for 13,843 lakes and reservoirs with areas greater than 0.1 km2 and all-season ATL13 products across the globe, in which 2257 targets are smaller than 1 km2. In total, the average valid number of months covered by ICESat-2 is 5.41 months and only 204 of 13,843 lakes and reservoirs have water levels in all the months in 2019. In situ water level data from 21 gauge stations across the United States and 12 gauge stations across Australia were collected to assess the monthly lake/reservoir water levels, which exhibited a high accuracy (RMSE = 0.08 m, r = 0.999). According to comparisons between the monthly water levels and changes from ATL08 products in another study and ATL13 products in this study, we found that both products can accurately estimate the monthly water level of lakes and reservoirs, but water levels derived from ATL13 products exhibited a higher accuracy compared with water levels derived from ATL08 products (RMSE = 0.28 m, r = 0.999). In general, the ATL13 product is more convenient because the HydroLAKES mask of inland water bodies, the orthometric height (with respect to the EGM2008 geoid) of water surfaces, and several data quality parameters specific to water surfaces were involved in the ATL13 product.
Comparative Evaluation of Mapping Accuracy between UAV Video versus Photo Mosaic for the Scattered Urban Photovoltaic Panel
Authors: Hwang Young-Seok , Schlüter Stephan , Park Seong-Il , Um Jung-Sup
Published: July 2021

It is common practice for unmanned aerial vehicle (UAV) flight planning to target an entire area surrounding a single rooftop’s photovoltaic panels while investigating solar-powered roofs that account for only 1% of the urban roof area. It is very hard for the pre-flight route setting of the autopilot for a specific area (not for a single rooftop) to capture still images with high overlapping rates of a single rooftop’s photovoltaic panels. This causes serious unnecessary data redundancy by including the surrounding area because the UAV is unable to focus on the photovoltaic panel installed on the single rooftop. The aim of this research was to examine the suitability of a UAV video stream for building 3-D ortho-mosaics focused on a single rooftop and containing the azimuth, aspect, and tilts of photovoltaic panels. The 3-D position accuracy of the video stream-based ortho-mosaic has been shown to be similar to that of the autopilot-based ortho-photo by satisfying the mapping accuracy of the American Society for Photogrammetry and Remote Sensing (ASPRS): 3-D coordinates (0.028 m) in 1:217 mapping scale. It is anticipated that this research output could be used as a valuable reference in employing video stream-based ortho-mosaics for widely scattered single rooftop solar panels in urban settings.
An Improved Single-Epoch Attitude Determination Method for Low-Cost Single-Frequency GNSS Receivers
Authors: Wang Xinzhe , Yao Yibin , Xu Chaoqian , Zhao Yinzhi , Zhang Huan
Published: July 2021

GNSS attitude determination has been widely used in various navigation and positioning applications, due to its advantages of low cost and high efficiency. The navigation positioning and attitude determination modules in the consumer market mostly use low-cost receivers and face many problems such as large multipath effects, frequent cycle slips and even loss of locks. Ambiguity fixing is the key to GNSS attitude determination and will face more challenges in the complex urban environment. Based on the CLAMBDA algorithm, this paper proposes a CLAMBDA-search algorithm based on the multi-baseline GNSS model. This algorithm improves the existing CLAMBDA method through a fixed geometry constraint among baselines in the vehicle coordinate system. A fixed single-baseline solution reduces two degrees of freedom of vehicle rigid body, and a global minimization search for the ambiguity objective function in the other degree of freedom is conducted to calculate the baseline vector and its Euler angles. In addition, in order to make up for the shortcomings of short baseline ambiguity in complex environments, this paper proposes different validation strategies. Using three low-cost receivers (ublox M8T) and patch antennas, static and dynamic on-board experiments with different baseline length set-ups were carried out in different environments. Both the experiments prove that the method proposed in this paper has greatly improved the ambiguity fixing performance and also the Euler angle calculation accuracy, with an acceptable calculation burden. It is a practical vehicle-mounted attitude determination algorithm.
Mapping Tree Height in Burkina Faso Parklands with TanDEM-X
Authors: Soja Maciej J. , Karlson Martin , Bayala Jules , Bazié Hugues R. , Sanou Josias , Tankoano Boalidioa , Eriksson Leif E. B. , Reese Heather , Ostwald Madelene , Ulander Lars M. H.
Published: July 2021

Mapping of tree height is of great importance for management, planning, and research related to agroforestry parklands in Africa. In this paper, we investigate the potential of spotlight-mode data from the interferometric synthetic aperture radar (InSAR) satellite system TanDEM-X (TDM) for mapping of tree height in Saponé, Burkina Faso, a test site characterised by a low average canopy cover (~15%) and a mean tree height of 9.0 m. Seven TDM acquisitions from January–April 2018 are used jointly to create high-resolution (~3 m) maps of interferometric phase height and mean canopy elevation, the latter derived using a new, model-based processing approach compensating for some effects of the side-looking geometry of SAR. Compared with phase height, mean canopy elevation provides a more accurate representation of tree height variations, a better tree positioning accuracy, and better tree height estimation performance when assessed using 915 trees inventoried in situ and representing 15 different species/genera. We observe and discuss two bias effects, and we use empirical models to compensate for these effects. The best-performing model using only TDM data provides tree height estimates with a standard error (SE) of 2.8 m (31% of the average height) and a correlation coefficient of 75%. The estimation performance is further improved when TDM height data are combined with in situ measurements; this is a promising result in view of future synergies with other remote sensing techniques or ground measurement-supported monitoring of well-known trees.
Crop Classification Using MSCDN Classifier and Sparse Auto-Encoders with Non-Negativity Constraints for Multi-Temporal, Quad-Pol SAR Data
Authors: Zhang Wei-Tao , Wang Min , Guo Jiao , Lou Shun-Tian
Published: July 2021

Accurate and reliable crop classification information is a significant data source for agricultural monitoring and food security evaluation research. It is well-known that polarimetric synthetic aperture radar (PolSAR) data provides ample information for crop classification. Moreover, multi-temporal PolSAR data can further increase classification accuracies since the crops show different external forms as they grow up. In this paper, we distinguish the crop types with multi-temporal PolSAR data. First, due to the “dimension disaster” of multi-temporal PolSAR data caused by excessive scattering parameters, a neural network of sparse auto-encoder with non-negativity constraint (NC-SAE) was employed to compress the data, yielding efficient features for accurate classification. Second, a novel crop discrimination network with multi-scale features (MSCDN) was constructed to improve the classification performance, which is proved to be superior to the popular classifiers of convolutional neural networks (CNN) and support vector machine (SVM). The performances of the proposed method were evaluated and compared with the traditional methods by using simulated Sentinel-1 data provided by European Space Agency (ESA). For the final classification results of the proposed method, its overall accuracy and kappa coefficient reaches 99.33% and 99.19%, respectively, which were almost 5% and 6% higher than the CNN method. The classification results indicate that the proposed methodology is promising for practical use in agricultural applications.
Additional Reference Height Error Analysis for Baseline Calibration Based on a Distributed Target DEM in TwinSAR-L
Authors: Qi Yang , Wang Yu , Hong Jun , Du Shaoyan
Published: July 2021

In this paper, additional reference height errors, caused by the penetration depth and Signal to Noise Ratio (SNR) decorrelation in desert regions in L-band spaceborne bistatic interferemetric SAR, will introduce significant errors in nowadays baseline calibration method based on distributed target and consequent DEM products. To quantify these two errrors, this paper takes the TwinSAR-L mission as an example, gives an introduction of TwinSAR-L, outlines the theoretical baseline accuracy requirements that need to be satisfied in the TwinSAR-L mission and addresses the additional reference height errors caused by the penetration depth and SNR decorrelation in desert regions in general by taking the TwinSAR-L mission as an example. Based on ALOS-2 data from a dry desert region in the east of Xing Jiang, this paper quantitatively analyzes these additional reference height errors. The results show that the additional reference height errors resulted from the penetration depth and the SNR decorrelation are 1.295 m and 1.39 m, respectively, which would even cause 6.4 mm and 8.6 mm baseline calibration errors. These errors would seriously degrade the baseline calibration accuracy and the consequent DEM product quality. Therefore, our analysis is of great significance not only for baseline calibration, but also for high-quality DEM’s generation, accuracy assessment and geophysical parameters’ quantitative inversion and application.
Spectral-Locational-Spatial Manifold Learning for Hyperspectral Images Dimensionality Reduction
Authors: Li Na , Zhou Deyun , Shi Jiao , Wu Tao , Gong Maoguo
Published: July 2021

Dimensionality reduction (DR) plays an important role in hyperspectral image (HSI) classification. Unsupervised DR (uDR) is more practical due to the difficulty of obtaining class labels and their scarcity for HSIs. However, many existing uDR algorithms lack the comprehensive exploration of spectral-locational-spatial (SLS) information, which is of great significance for uDR in view of the complex intrinsic structure in HSIs. To address this issue, two uDR methods called SLS structure preserving projection (SLSSPP) and SLS reconstruction preserving embedding (SLSRPE) are proposed. Firstly, to facilitate the extraction of SLS information, a weighted spectral-locational (wSL) datum is generated to break the locality of spatial information extraction. Then, a new SLS distance (SLSD) excavating the SLS relationships among samples is designed to select effective SLS neighbors. In SLSSPP, a new uDR model that includes a SLS adjacency graph based on SLSD and a cluster centroid adjacency graph based on wSL data is proposed, which compresses intraclass samples and approximately separates interclass samples in an unsupervised manner. Meanwhile, in SLSRPE, for preserving the SLS relationship among target pixels and their nearest neighbors, a new SLS reconstruction weight was defined to obtain the more discriminative projection. Experimental results on the Indian Pines, Pavia University and Salinas datasets demonstrate that, through KNN and SVM classifiers with different classification conditions, the classification accuracies of SLSSPP and SLSRPE are approximately 4.88%, 4.15%, 2.51%, and 2.30%, 5.31%, 2.41% higher than that of the state-of-the-art DR algorithms.
Parameterization of the Individual Tree Detection Method Using Large Dataset from Ground Sample Plots and Airborne Laser Scanning for Stands Inventory in Coniferous Forest
Authors: Kolendo Łukasz , Kozniewski Marcin , Ksepko Marek , Chmur Szymon , Neroj Bożydar
Published: July 2021

Highly accurate and extensive datasets are needed for the practical implementation of precision forestry as a method of forest ecosystem management. Proper processing of huge datasets involves the necessity of the appropriate selection of methods for their analysis and optimization. In this paper, we propose a concept for and implementation of a data preprocessing algorithm, and a method for the empirical verification of selected individual tree detection (ITD) algorithms, based on Airborne Laser Scanning (ALS) data. In our study, we used ALS data and very extensive dendrometric field measurements (including over 21,000 trees on 522 circular sample plots) in the economic and protective coniferous stands of north-eastern Poland. Our algorithm deals well with the overestimation problems of tree top detection. Furthermore, we analyzed segmentation parameters for the two currently dominant ITD methods: Watershed (WS) and Local Maximum Filter with Growing Region (LMF+GR). We optimized them with respect to minimizing the Root Mean Square Error (RMSE) and Mean Absolute Percentage Error (MAPE). Additionally, our results show the crucial importance of the quality of empirical data for the correct evaluation of the accuracy of ITD algorithms.
Prior Position- and ZWD-Constrained PPP for Instantaneous Convergence in Real-Time Kinematic Application
Authors: Tang Xu , Jin Shuanggen , Roberts Gethin Wyn
Published: July 2021

PPP using Kalman filter typically takes half an hour to achieve high positioning precision, which is required for small movements detection. Many dataset gaps due to temporary GPS receiver signal loss challenge the feasibility of PPP in GPS applications for kinematic precise positioning. Additional convergence time is needed before PPP reaches the required precision again. In this study, Partial parameters were estimated by using the position and ZWD as prior constraint. The solved partial parameters were applied to initialize the Kalman filter for PPP instantaneous re-convergence. A set of bridge GPS data with logging gaps were used to validate the re-convergence performance of improved PPP. The results show that the displacements from position-constrained PPP with initialized variance are 0.14 m, 0.09 m and 0.05 m, which are much better than those from standard PPP. The precision of displacement from position- and ZWD-constrained PPP with initialized variance is slightly improved when compared with that from position-constrained PPP with initialized variance at all 3 surveying points. The bridge experiment verifies that the displacement time series of improved PPP instantaneously converges at the first epoch of all signal reacquired, in contrast, standard PPP deviates by meters. This finding suggests that improved PPP can successfully deal with the GPS data logging gaps for instantaneous convergence.
Internet-of-Things-Based Geotechnical Monitoring Boosted by Satellite InSAR Data
Authors: Guilhot Denis , Martinez del Hoyo Toni , Bartoli Andrea , Ramakrishnan Pooja , Leemans Gijs , Houtepen Martijn , Salzer Jacqueline , Metzger John S. , Maknavicius Gintaris
Published: July 2021

Landslides, often a side effect of mining activities, pose a significant risk to humans and infrastructures such as urban areas, power lines, and dams. Operational ground motion monitoring can help detect the spatial pattern of surface changes and their evolution over time. In this technical note, a commercial, cost-effective method combining a network of geotechnical surface sensors with the InSAR data was reported for the first time to accurately monitor surface displacement. The correlation of both data sets is demonstrated in the Gediminas Castle testbed, where slope failure events were detected. Two specific events were analyzed, and possible causes proposed. The combination of techniques allows one to detect the precursors of the events and characterize the consequences of the failures in different areas in proximity to the castle walls, since the solution allows for the confirmation of long-term drifts and sudden movements in real time. The data from the in situ sensors were also used to refine the satellite data analysis. The results demonstrate that not all events pose a direct threat to the safety of the structure monitored.
Application of TLS Remote Sensing Data in the Analysis of the Load-Carrying Capacity of Structural Steel Elements
Authors: Wałach Daniel , Kaczmarczyk Grzegorz Piotr
Published: July 2021

This paper proposes the use of terrestrial laser scanning (TLS) measurements together with finite element method (FEM) numerical modeling to assess the current technical condition. The main aim of the paper was to evaluate the effect of point cloud size reduction on the quality of the geometric model and the ability to represent the corrosion level in assessing its load-carrying capacity. In this study, a standard scanning was performed on a historical object and a point cloud of a selected corroded element was generated. In order to further process the data, gradual reductions were made in the number of points from which meshes representing the geometry of the selected beam were created. Inaccuracy analyses of the meshes generated on the reduced point clouds were performed. Numerical analysis was then conducted for the selected mesh generated from the reduced point cloud. The results identified the locations of maximum stresses. The presented analysis showed that by developing the presented measurement and computational technique, laser scanning can be used to determine the degree of corrosion of hard-to-reach steel elements.
A Validated and Accurate Method for Quantifying and Extrapolating Mangrove Above-Ground Biomass Using LiDAR Data
Authors: Salum Rafaela B. , Robinson Sharon A. , Rogers Kerrylee
Published: July 2021

LiDAR data and derived canopy height models can provide useful information about mangrove tree heights that assist with quantifying mangrove above-ground biomass. This study presents a validated method for quantifying mangrove heights using LiDAR data and calibrating this against plot-based estimates of above-ground biomass. This approach was initially validated for the mangroves of Darwin Harbour, in Northern Australia, which are structurally complex and have high species diversity. Established relationships were then extrapolated to the nearby West Alligator River, which provided the opportunity to quantify biomass at a remote location where intensive fieldwork was limited. Relationships between LiDAR-derived mangrove heights and mean tree height per plot were highly robust for Ceriops tagal, Rhizophora stylosa and Sonneratia alba (r2 = 0.84–0.94, RMSE = 0.03–0.91 m; RMSE% = 0.07%–11.27%), and validated well against an independent dataset. Additionally, relationships between the derived canopy height model and field-based estimates of above-ground biomass were also robust and validated (r2 = 0.73–0.90, RMSE = 141.4 kg–1098.58 kg, RMSE% of 22.94–39.31%). Species-specific estimates of tree density per plot were applied in order to align biomass of individual trees with the resolution of the canopy height model. The total above-ground biomass at Darwin Harbour was estimated at 120 t ha−1 and comparisons with prior estimates of mangrove above-ground biomass confirmed the accuracy of this assessment. To establish whether accurate and validated relationships could be extrapolated elsewhere, the established relationships were applied to a LiDAR-derived canopy height model at nearby West Alligator River. Above-ground biomass derived from extrapolated relationships was estimated at 206 t ha−1, which compared well with prior biomass estimates, confirming that this approach can be extrapolated to remote locations, providing the mangrove forests are biogeographically similar. The validated method presented in this study can be used for reporting mangrove carbon storage under national obligations, and is useful for quantifying carbon within various markets.
Revisiting Trans-Arctic Maritime Navigability in 2011–2016 from the Perspective of Sea Ice Thickness
Authors: Zhou Xiangying , Min Chao , Yang Yijun , Landy Jack C. , Mu Longjiang , Yang Qinghua
Published: July 2021

Arctic navigation has become operational in recent decades with the decline in summer sea ice. To assess the navigability of trans-Arctic passages, combined model and satellite sea ice thickness (CMST) data covering both freezing seasons and melting seasons are integrated with the Arctic Transportation Accessibility Model (ATAM). The trans-Arctic navigation window and transit time are thereby obtained daily from modeled sea ice fields constrained by satellite observations. Our results indicate that the poorest navigability conditions for the maritime Arctic occurred in 2013 and 2014, particularly in the Northwest Passage (NWP) with sea ice blockage. The NWP has generally exhibited less favorable navigation conditions and shorter navigable windows than the Northern Sea Route (NSR). For instance, in 2013, Open Water (OW) vessels that can only safely resist ice with a thickness under 15 cm had navigation windows of 47 days along the NSR (45% shorter than the 2011–2016 mean) and only 13 days along the NWP (80% shorter than the 2011–2016 mean). The longest navigation windows were in 2011 and 2015, with lengths of 103 and 107 days, respectively. The minimum transit time occurred in 2012, when more northward routes were accessible, especially in the Laptev Sea and East Siberian Sea with the sea ice edge retreated. The longest navigation windows for Polar Class 6 (PC6) vessels with a resistance to ice thickness up to 120 cm reached more than 200 days. PC6 vessels cost less transit time and exhibit less fluctuation in their navigation windows compared with OW vessels because of their ice-breaking capability. Finally, we found that restricted navigation along the NSR in 2013 and 2014 was related to the shorter periods of navigable days in the East Siberian Sea and Vilkitskogo Strait, with local blockages of thick ice having a disproportionate impact on the total transit. Shorter than usual navigable windows in the Canadian Arctic Archipelago and Beaufort Sea shortened the windows for entire routes of the NWP in 2013 and 2014.
A Sparse Denoising-Based Super-Resolution Method for Scanning Radar Imaging
Authors: Zhang Qiping , Zhang Yin , Zhang Yongchao , Huang Yulin , Yang Jianyu
Published: July 2021

Scanning radar enables wide-range imaging through antenna scanning and is widely used for radar warning. The Rayleigh criterion indicates that narrow beams of radar are required to improve the azimuth resolution. However, a narrower beam means a larger antenna aperture. In practical applications, due to platform limitations, the antenna aperture is limited, resulting in a low azimuth resolution. The conventional sparse super-resolution method (SSM) has been proposed for improving the azimuth resolution of scanning radar imaging and achieving superior performance. This method uses the L1 norm to represent the sparse prior of the target and solves the L1 regularization problem to achieve super-resolution imaging under the regularization framework. The resolution of strong-point targets is improved efficiently. However, for some targets with typical shapes, the strong sparsity of the L1 norm treats them as strong-point targets, resulting in the loss of shape characteristics. Thus, we can only see the strong points in its processing results. However, in some applications that need to identify targets in detail, SSM can lead to false judgments. In this paper, a sparse denoising-based super-resolution method (SDBSM) is proposed to compensate for the deficiency of traditional SSM. The proposed SDBSM uses a sparse minimization scheme for denoising, which helps to reduce the influence of noise. Then, the super-resolution imaging is achieved by alternating iterative denoising and deconvolution. As the proposed SDBSM uses the L1 norm for denoising rather than deconvolution, the strong sparsity constraint of the L1 norm is reduced. Therefore, it can effectively preserve the shape of the target while improving the azimuth resolution. The performance of the proposed SDBSM was demonstrated via simulation and real data processing results.
Quad-FPN: A Novel Quad Feature Pyramid Network for SAR Ship Detection
Authors: Zhang Tianwen , Zhang Xiaoling , Ke Xiao
Published: July 2021

Ship detection from synthetic aperture radar (SAR) imagery is a fundamental and significant marine mission. It plays an important role in marine traffic control, marine fishery management, and marine rescue. Nevertheless, there are still some challenges hindering accuracy improvements of SAR ship detection, e.g., complex background interferences, multi-scale ship feature differences, and indistinctive small ship features. Therefore, to address these problems, a novel quad feature pyramid network (Quad-FPN) is proposed for SAR ship detection in this paper. Quad-FPN consists of four unique FPNs, i.e., a DEformable COnvolutional FPN (DE-CO-FPN), a Content-Aware Feature Reassembly FPN (CA-FR-FPN), a Path Aggregation Space Attention FPN (PA-SA-FPN), and a Balance Scale Global Attention FPN (BS-GA-FPN). To confirm the effectiveness of each FPN, extensive ablation studies are conducted. We conduct experiments on five open SAR ship detection datasets, i.e., SAR ship detection dataset (SSDD), Gaofen-SSDD, Sentinel-SSDD, SAR-Ship-Dataset, and high-resolution SAR images dataset (HRSID). Qualitative and quantitative experimental results jointly reveal Quad-FPN’s optimal SAR ship detection performance compared with the other 12 competitive state-of-the-art convolutional neural network (CNN)-based SAR ship detectors. To confirm the excellent migration application capability of Quad-FPN, the actual ship detection in another two large-scene Sentinel-1 SAR images is conducted. Their satisfactory detection results indicate the practical application value of Quad-FPN in marine surveillance.